The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Harvey R. Herschman - One of the best experts on this subject based on the ideXlab platform.
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a tumor agnostic therapeutic strategy for hexokinase 1 null hexokinase 2 positive cancers
Cancer Research, 2019Co-Authors: Shili Xu, Harvey R. HerschmanAbstract:Since Warburg9s observation that most cancers exhibit elevated glycolysis, decades of research have attempted to reduce tumor glucose utilization as a therapeutic approach. Hexokinase (HK) activity is the first glycolytic enzymatic step; despite many attempts to inhibit HK activity, none has reached clinical application. Identification of HK isoforms, and recognition that most tissues express only HK1 while most tumors express HK1 and HK2, stimulated reducing HK2 activity as a therapeutic option. However, studies using HK2 shRNA and isogenic HK1+HK2- and HK1+HK2+ tumor cell pairs demonstrated that tumors expressing only HK1, while exhibiting reduced glucose consumption, progressed in vivo as well as tumors expressing both HK1 and HK2. However, there exist HK1-HK2+ tumor subpopulations among many cancers. shRNA HK2 suppression in HK1-HK2+ liver cancer cells reduced xenograft tumor progression, in contrast to HK1+HK2+ cells. HK2 Inhibition, and partial inhibition of both oxidative phosphorylation and fatty acid oxidation using HK2 shRNA and small molecule drugs, prevented human liver HK1-HK2+ cancer xenograft progression. Using human multiple myeloma xenografts and mouse allogeneic models to identify potential clinical translational agents, triple therapies that include antisense HK2 oligonucleotides, metformin and perhexiline prevent progression. These results suggest an agnostic approach for HK1-HK2+ cancers, regardless of tissue origin.
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a tumor agnostic therapeutic strategy for hexokinase 1 null hexokinase 2 positive cancers
Cancer Research, 2019Co-Authors: Harvey R. HerschmanAbstract:Since Warburg's observation that most cancers exhibit elevated glycolysis, decades of research have attempted to reduce tumor glucose utilization as a therapeutic approach. Hexokinase (HK) activity is the first glycolytic enzymatic step; despite many attempts to inhibit HK activity, none has reached clinical application. Identification of HK isoforms, and recognition that most tissues express only HK1 while most tumors express HK1 and HK2, stimulated reducing HK2 activity as a therapeutic option. However, studies using HK2 shRNA and isogenic HK1+HK2- and HK1+HK2+ tumor cell pairs demonstrated that tumors expressing only HK1, while exhibiting reduced glucose consumption, progressed in vivo as well as tumors expressing both HK1 and HK2. However, HK1-HK2+ tumor subpopulations exist among many cancers. shRNA HK2 suppression in HK1-HK2+ liver cancer cells reduced xenograft tumor progression, in contrast to HK1+HK2+ cells. HK2 inhibition, and partial inhibition of both oxidative phosphorylation and fatty acid oxidation using HK2 shRNA and small-molecule drugs, prevented human liver HK1-HK2+ cancer xenograft progression. Using human multiple myeloma xenografts and mouse allogeneic models to identify potential clinical translational agents, triple therapies that include antisense HK2 oligonucleotides, metformin, and perhexiline prevent progression. These results suggest an agnostic approach for HK1-HK2+ cancers, regardless of tissue origin.
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hexokinase 2 is targetable for HK1 negative hk2 positive tumors from a wide variety of tissues of origin
The Journal of Nuclear Medicine, 2019Co-Authors: Shili Xu, Arthur Catapang, Thomas G Graeber, Nicholas A Bayley, Daniel Braas, Harvey R. HerschmanAbstract:: Although absent in most adult tissues, hexokinase 2 (HK2) is expressed in a majority of tumors and contributes to increased glucose consumption and to in vivo tumor 18F-FDG PET signaling. Methods: Both HK2 knockdown and knockout approaches were used to investigate the role of HK2 in cancer cell proliferation, in vivo xenograft tumor progression and 18F-FDG tumor accumulation. BioProfiler analysis monitored cell culture glucose consumption and lactate production; 18F-FDG PET/CT monitored in vivo tumor glucose accumulation. Cancer Cell Line Encyclopedia data were analyzed for HK1 and HK2 expression. Results: Neither cell proliferation in culture nor xenograft tumor progression are inhibited by HK2 knockdown or knockout in cancer cells that express HK1 and HK2. However, cancer subsets from a variety of tissues of origin express only HK2, but not HK1. In contrast to HK1+HK2+ cancers, HK2 knockdown in HK1-HK2+ cancer cells results in inhibition of cell proliferation, colony formation and xenograft tumor progression. Moreover, HK1KOHK2+ cancer cells are susceptible to HK2 inhibition, in contrast to their isogenic HK1+HK2+ parental cells. Conclusion: HK1 and HK2 expression are redundant in tumors; either can provide sufficient aerobic glycolysis for tumor growth; despite a reduction in 18F-FDG PET signal. Therapeutic HK2 inhibition is likely to be restricted to HK1-HK2+ tumor subsets, but stratification of tumors that express HK2, but not HK1, should identify tumors treatable with emerging HK2 specific inhibitors.
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hexokinase 2 is targetable for HK1 negative hk2 positive tumors from a wide variety of tissues of origin
The Journal of Nuclear Medicine, 2019Co-Authors: Shili Xu, Arthur Catapang, Thomas G Graeber, Nicholas A Bayley, Daniel Braas, Harvey R. HerschmanAbstract:: Although absent in most adult tissues, hexokinase 2 (HK2) is expressed in a majority of tumors and contributes to increased glucose consumption and to in vivo tumor 18F-FDG PET signaling. Methods: Both HK2 knockdown and knockout approaches were used to investigate the role of HK2 in cancer cell proliferation, in vivo xenograft tumor progression and 18F-FDG tumor accumulation. BioProfiler analysis monitored cell culture glucose consumption and lactate production; 18F-FDG PET/CT monitored in vivo tumor glucose accumulation. Cancer Cell Line Encyclopedia data were analyzed for HK1 and HK2 expression. Results: Neither cell proliferation in culture nor xenograft tumor progression are inhibited by HK2 knockdown or knockout in cancer cells that express HK1 and HK2. However, cancer subsets from a variety of tissues of origin express only HK2, but not HK1. In contrast to HK1+HK2+ cancers, HK2 knockdown in HK1-HK2+ cancer cells results in inhibition of cell proliferation, colony formation and xenograft tumor progression. Moreover, HK1KOHK2+ cancer cells are susceptible to HK2 inhibition, in contrast to their isogenic HK1+HK2+ parental cells. Conclusion: HK1 and HK2 expression are redundant in tumors; either can provide sufficient aerobic glycolysis for tumor growth; despite a reduction in 18F-FDG PET signal. Therapeutic HK2 inhibition is likely to be restricted to HK1-HK2+ tumor subsets, but stratification of tumors that express HK2, but not HK1, should identify tumors treatable with emerging HK2 specific inhibitors.
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a precision therapeutic strategy for hexokinase 1 null hexokinase 2 positive cancers
Cancer and Metabolism, 2018Co-Authors: Shili Xu, Arthur Catapang, Linsey Stiles, Thomas G Graeber, Robert Damoiseaux, Orian S Shirihai, Daniel Braas, Harvey R. HerschmanAbstract:Precision medicine therapies require identification of unique molecular cancer characteristics. Hexokinase (HK) activity has been proposed as a therapeutic target; however, different hexokinase isoforms have not been well characterized as alternative targets. While HK2 is highly expressed in the majority of cancers, cancer subtypes with differential HK1 and HK2 expression have not been characterized for their sensitivities to HK2 silencing. HK1 and HK2 expression in the Cancer Cell Line Encyclopedia dataset was analyzed. A doxycycline-inducible shRNA silencing system was used to examine the effect of HK2 knockdown in cultured cells and in xenograft models of HK1−HK2+ and HK1+HK2+ cancers. Glucose consumption and lactate production rates were measured to monitor HK activity in cell culture, and 18F-FDG PET/CT was used to monitor HK activity in xenograft tumors. A high-throughput screen was performed to search for synthetically lethal compounds in combination with HK2 inhibition in HK1−HK2+ liver cancer cells, and a combination therapy for liver cancers with this phenotype was developed. A metabolomic analysis was performed to examine changes in cellular energy levels and key metabolites in HK1−HK2+ cells treated with this combination therapy. The CRISPR Cas9 method was used to establish isogenic HK1+HK2+ and HK1−HK2+ cell lines to evaluate HK1−HK2+ cancer cell sensitivity to the combination therapy. Most tumors express both HK1 and HK2, and subsets of cancers from a wide variety of tissues of origin express only HK2. Unlike HK1+HK2+ cancers, HK1−HK2+ cancers are sensitive to HK2 silencing-induced cytostasis. Synthetic lethality was achieved in HK1−HK2+ liver cancer cells, by the combination of DPI, a mitochondrial complex I inhibitor, and HK2 inhibition, in HK1−HK2+ liver cancer cells. Perhexiline, a fatty acid oxidation inhibitor, further sensitizes HK1−HK2+ liver cancer cells to the complex I/HK2-targeted therapeutic combination. Although HK1+HK2+ lung cancer H460 cells are resistant to this therapeutic combination, isogenic HK1KOHK2+ cells are sensitive to this therapy. The HK1−HK2+ cancer subsets exist among a wide variety of cancer types. Selective inhibition of the HK1−HK2+ cancer cell-specific energy production pathways (HK2-driven glycolysis, oxidative phosphorylation and fatty acid oxidation), due to the unique presence of only the HK2 isoform, appears promising to treat HK1−HK2+ cancers. This therapeutic strategy will likely be tolerated by most normal tissues, where only HK1 is expressed.
E M Eddy - One of the best experts on this subject based on the ideXlab platform.
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spermatogenic cell specific type 1 hexokinase is the predominant hexokinase in sperm
Molecular Reproduction and Development, 2008Co-Authors: Noriko Nakamura, Chisato Mori, Deborah A Obrien, Haruna Shibata, E M EddyAbstract:Hexokinase is the first enzyme in the glycolytic pathway and utilizes ATP to convert glucose to glucose-6-phosphate (G6P). We previously identified three variant transcripts of HK1 that are expressed specifically in spermatogenic cells, have different 5' untranslated regions, and encode a protein (HK1S, spermatogenic cell-specific type 1 hexokinase) in which the porin-binding domain (PBD) of HK1 is replaced by a novel N-terminal spermatogenic cell-specific region (SSR). However, the level of expression of the individual variant transcripts or of the other members of the hexokinase gene family (Hk2, Hk3, and Gck) in spermatogenic cells remains uncertain. We show that HK1, Hk2, and Hk3 transcripts levels are quite low in spermatocytes and spermatids and Gck transcripts are relatively abundant in spermatids, but that glucokinase (GCK) is not detected in spermatozoa. Using real time RT-PCR (qPCR) with primers specific for each of the three variant forms and RNA from whole testis and isolated germ cells, we found that transcripts for HK1_v2 and HK1_v3, but not for HK1_v1, are relatively high in spermatids. Similar results were seen using spermatogenic cells isolated by laser-capture microdissection (LCM). Immunoblotting studies found that HK1S is abundant in sperm, and immunostaining confirmed that HK1S is located mainly in the principal piece of the sperm flagellum, where other spermatogenic cell-specific glycolytic enzymes have been found. These results strongly suggest that HK1, HK2, HK3, and GCK are unlikely to have a role in glycolysis in sperm and that HK1S encoded by HK1_v2 and HK1_v3 serves this role.
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mouse spermatogenic cell specific type 1 hexokinase mHK1 s transcripts are expressed by alternative splicing from the mHK1 gene and the HK1 s protein is localized mainly in the sperm tail
Molecular Reproduction and Development, 1998Co-Authors: Chisato Mori, J E Welch, Noriko Nakamura, Hideo Gotoh, Eugenia H Goulding, Makio Fujioka, E M EddyAbstract:Unique type 1 hexokinase (HK1) mRNAs are present in mouse spermatogenic cells (mHK1-s). They encode a spermatogenic cell-specific sequence region (SSR) but not the porin-binding domain (PBD) necessary for HK1 binding to porin on the outer mitochondrial membrane. This study determined the origin of the multiple HK1-s transcripts in mouse spermatogenic cells and verified that they are translated in mouse spermatogenic cells. It also showed that a single mHK1 gene encodes the mHK1 transcripts of somatic cells and the mHK1-sa and mHK1-sb transcripts of spermatogenic cells, that alternative exons are used during mHK1 gene expression in mouse spermatogenic cells, and that mHK1-S is translated in mouse spermatogenic cells and is localized mainly with the fibrous sheath in the tail region, not with the mitochondria in the midpiece of mouse sperm.
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unique hexokinase messenger ribonucleic acids lacking the porin binding domain are developmentally expressed in mouse spermatogenic cells
Biology of Reproduction, 1993Co-Authors: Chisato Mori, J E Welch, Kerry D Fulcher, Deborah A Obrien, E M EddyAbstract:We have identified cDNAs representing three hexokinase mRNAs (HK1-sa, HK1-sb, HK1-sc) by screening mouse spermatogenic cell cDNA libraries with a mouse hepatoma cell line hexokinase (HK1) cDNA [Arora KK, Fanciulli M, Pederson PL. J Biol Chem 1990; 265:6481-6488]. Although all three cDNAs show 99% identity to the somatic HK1 cDNA sequence throughout most of their coding region, they differ from this sequence at the 5' end. They contain a common spermatogenic cell-specific sequence and a sequence unique to each cDNA immediately 5' to the common domain. However, they lack the porin-binding domain (PBD) present in this region of HK1, used for binding to a pore-forming protein in the outer mitochondrial membrane. These observations appear to support a model proposed by others for hexokinase gene evolution in mammals. In addition, we found that HK1-sb has an internal sequence that is not present in HK1, HK1-sa, or HK1-sc. Moreover, HK1-sa and HK1-sb transcripts are developmentally expressed in mouse spermatogenic cells. HK1-sa mRNA is first expressed during meiosis and continues to be present in postmeiotic germ cells, while the more abundant HK1-sb mRNA is detected only in postmeiotic germ cells. These and other findings suggest that enzymes encoded by HK1-sa, HK1-sb, and HK1-sc are present only in spermatogenic cells.
David A. Greenhalgh - One of the best experts on this subject based on the ideXlab platform.
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abstract 930 induciblerock 2 rashacooperation requires wound promotion to achieve malignancy in transgenic mouse skin carcinogenesis whereas induciblerock 2 ptenloss fails to achieve benign papilloma
Cancer Research, 2014Co-Authors: Siti Fathiah Masre, Michael S Samuel, Michael F Olson, David A. GreenhalghAbstract:Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA To study tumour progression mechanism in vivo, ROCK 2 signalling deregulation and co-operation with activated rasHa or PTEN loss was investigated in transgenic mouse skin carcinogenesis. Transgenic mice that expressed a 4-hydroxytamoxifen (4HT)-activated human ROCK 2-estrogen receptor fusion transgene from a keratin 14 promoter [K14.ROCKer] were crossed to mice expressing activated rasHa exclusively in epidermal transit amplifying keratinocytes [HK1.ras-ROCKer] or mice where cutaneous PTEN loss was achieved in basal layers, hair follicles and stem cell keratinocytes via topical RU486 treatment of bi-genic K14.creP/Δ5PTENflx genotypes [K14.Δ5PTEN-ROCKer]. Initial 4HT-treatments of K14.ROCKer mice [3/wk; 26 wks] induced epidermal and follicular hyperplasia but no papillomas; whilst treatment of HK1.ras line 1205 gave ear tag papillomas [10-12 wks] typically smaller than vehicle controls, but no malignant conversion. In contrast, 4-HT treated HK1.ras-Rocker papillomas [10-12 wks] exhibited areas of carcinoma in situ and well-differentiated squamous cell carcinoma [wdSCC]. With time [16-20wks] wdSCC areas increased, concomitant with loss of p53, increased p-AKT and altered differentiation marker expression; however histotypes remained wdSCC despite continued 4HT-induced Rock 2 activity; as confirmed by downstream MYPT-1 phosphorylation. Furthermore, papillomas regressed whenever 4-HT treated HK1.ras-Rocker mice lost ear tags, suggesting that continued promotion from wounding during papillomatogenesis was critical to achieving the appropriate [late-stage] papilloma context that facilitated Rock 2-mediated conversion. To test this idea, K14.ROCKer mice were crossed to HK1.ras line 1276, which is insensitive to wound promotion, and such bi-genic mice did not exhibit papillomas; while in reverse, demonstrating the need for initiation, classic TPA-promoted K14.ROCKer mice were also devoid of papillomas. In addition, as previously rasHa/PTENnull mice exhibited papillomas prone to conversion on acquisition of an additional oncogene [e.g. fos], K14.ROCKer mice were bred into a K14.cre.Δ5PTEN strain and bi-genic mice treated with Ru486 [3wks] and 4HT [>26wks]. Again, in the absence of rasHa no papillomas were observed and mice exhibited increased hyperplasia and altered differentiation consistent with disruption of epidermal physiology. These data suggest that Rock 2 deregulation plays major roles in malignant conversion and progression, and in cooperation with rasHa activation or PTEN loss, the mechanism requires additional promotion/initiation events during papillomatogenesis to create the context of late-stage papilloma where Rock 2 activities become causal; an idea being tested in tri-genic HK1.ras/Δ5PTEN-Rocker genotypes. Citation Format: Siti F. Masre, Michael S. Samuel, Michael F. Olson, David A. Greenhalgh. Inducible ROCK 2/rasHa cooperation requires wound promotion to achieve malignancy in transgenic mouse skin carcinogenesis, whereas inducible ROCK 2/PTEN loss fails to achieve benign papilloma. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 930. doi:10.1158/1538-7445.AM2014-930
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pten ablation in ras ha fos skin carcinogenesis invokes p53 dependent p21 to delay conversion while p53 independent p21 limits progression via cyclin d1 e2 inhibition
Oncogene, 2014Co-Authors: Denggao Yao, Jean A. Quinn, F H Macdonald, David A. GreenhalghAbstract:To investigate tumour progression mechanism in transgenic mouse skin carcinogenesis, inducible PTEN ablation (Δ5PTENflx) was targeted to the epidermis of mice expressing activated rasHa/fos oncogenes (HK1.ras and HK1.fos). RU486-treated HK1.ras/fos-Δ5PTENflx epidermis exhibited significant keratinocyte proliferation resulting in hyperplasia and proliferating cysts. While HK1.ras/fos-Δ5PTENflx papillomatogenesis was accelerated, malignant conversion was delayed and tumours exhibited well-differentiated squamous cell carcinoma (wdSCC) histotypes, suggesting inhibition of early-stage malignant progression. Immediate elevated p53/p21 expression was observed in HK1.ras/fos-Δ5PTENflx hyperplasia, cysts and papillomas, and while malignant conversion required p53 loss, elevated p21 expression persisted in most wdSCCs to limit further progression, unless p21 was also lost and wdSCC progressed to more aggressive carcinomas. In contrast, TPA-promoted (that is, c-fos-activated) bi-genic HK1.ras-Δ5PTENflx cohorts lost p53/p21 expression during early papillomatogenesis and rapidly produced poorly differentiated carcinomas (pdSCCs) with high BrdU-labelling and elevated cyclin D1/E2 expression levels, indicative of a progression mechanism driven by failures in cell-cycle control. Intriguingly, HK1.ras/fos-Δ5PTENflx wdSCCs did not exhibit similar failures, as western and immunofluorescence analysis found downregulated cyclin E2 whenever p21 persisted; further, while westerns detected elevated cyclin D1, immunofluorescence identified reduced expression in proliferative basal layer nuclei and a redistributed expression profile throughout p21-positive wdSCC keratinocytes. These data demonstrate that rapid early epidermal responses to rasHa/fos/ΔPTEN co-operation involve induction of p53/p21 to alter differentiation and divert excessive proliferation into cyst formation. Further, despite three potent oncogenic insults p53 loss was required for malignant conversion, and following p53 loss persistent, p53-independent p21 expression possessed the potency to limit early-stage malignant progression via cyclin D1/E2 inhibition.
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PTEN Loss Promotes rasHa-Mediated Papillomatogenesis via Dual Up-Regulation of AKT Activity and Cell Cycle Deregulation but Malignant Conversion Proceeds via PTEN-Associated Pathways
Cancer research, 2006Co-Authors: Denggao Yao, Claire L. Alexander, Jean A. Quinn, Michael J. Porter, David A. GreenhalghAbstract:PTEN tumor suppressor gene failure in ras(Ha)-activated skin carcinogenesis was investigated by mating exon 5 floxed-PTEN (Delta5PTEN) mice to HK1.ras mice that expressed a RU486-inducible cre recombinase (K14.creP). PTEN inactivation in K14.cre/PTEN(flx/flx) keratinocytes resulted in epidermal hyperplasia/hyperkeratosis and novel 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted papillomas, whereas HK1.ras/K14.cre/PTEN(flx/flx) cohorts displayed a rapid onset of papillomatogenesis due to a synergism of increased AKT activity and extracellular signal-regulated kinase (ERK) elevation. High 5-bromo-4-deoxyuridine labeling in Delta5PTEN papillomas showed that a second promotion mechanism centered on failures in cell cycle control. Elevated cyclin D1 was associated with both HK1.ras/ERK- and Delta5PTEN-mediated AKT signaling, whereas cyclin E2 overexpression seemed dependent on PTEN loss. Spontaneous HK1.ras/Delta5PTEN malignant conversion was rare, whereas TPA promotion resulted in conversion with high frequency. On comparison with all previous HK1.ras carcinomas, such TPA-induced carcinomas expressed atypical retention of keratin K1 and lack of K13, a unique marker profile exhibited by TPA-induced K14.cre/PTEN(flx/flx) papillomas that also lacked endogenous c-ras(Ha) activation. Moreover, in all PTEN-null tumors, levels of ras(Ha)-associated total ERK protein became reduced, whereas phosphorylated ERK and cyclin D1 were lowered in late-stage papillomas returning to elevated levels, alongside increased cyclin E2 expression, in TPA-derived carcinomas. Thus, during early papillomatogenesis, PTEN loss promotes ras(Ha) initiation via elevation of AKT activity and synergistic failures in cyclin regulation. However, in progression, reduced ras(Ha)-associated ERK protein and activity, increased Delta5PTEN-associated cyclin E2 expression, and unique K1/K13 profiles following TPA treatment suggest that PTEN loss, rather than ras(Ha) activation, gives rise to a population of cells with greater malignant potential.
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targeted overexpression of transforming growth factor alpha in the epidermis of transgenic mice elicits hyperplasia hyperkeratosis and spontaneous squamous papillomas
Cell Growth & Differentiation, 1993Co-Authors: Andrea M Dominey, Xiaojing Wang, Lloyd E King, Lillian B Nanney, T A Gagne, Klaus Sellheyer, Donnie S Bundman, Mary A Longley, Joseph A Rothnagel, David A. GreenhalghAbstract:To assess the effects of transforming growth factor alpha (TGF-alpha) on mammalian skin in vivo, we have targeted its expression to the epidermis of transgenic mice using a vector based on the human K1 (HK1) gene. Neonatal mice expressing the HK1.TGF-alpha transgene were often smaller than normal littermates and had precocious eyelid opening and wrinkled, scaly skin with diffuse alopecia. Juvenile transgenic mouse epidermis was uniformly hyperkeratotic, but this pattern was generally less pronounced in adult transgenic mice unless they expressed high levels of the HK1.TGF-alpha transgene. Spontaneous, squamous papillomas occurred at sites of wounding in adult mice expressing high levels of HK1.TGF-alpha; however, most were prone to regression. Immunoreactive TGF-alpha was 2-6 times higher in the epidermis of these HK1.TGF-alpha lines. Immunoreactive epidermal growth factor receptor had a normal pattern of expression in nonphenotypic adult epidermis, but a marked reduction in the receptor population was detected in hyperplastic newborn epidermis and phenotypic adult epidermis. Autoradiographic localization of 125I-epidermal growth factor showed a similar pattern of distribution, suggesting that the sites of increased TGF-alpha expression induced epidermal growth factor receptor down-regulation. These data demonstrate the in vivo effect of deregulated TGF-alpha expression on epidermal proliferation and differentiation and suggest a potential role for TGF-alpha in carcinogenesis and other hyperproliferative epidermal disorders.
Chisato Mori - One of the best experts on this subject based on the ideXlab platform.
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spermatogenic cell specific type 1 hexokinase is the predominant hexokinase in sperm
Molecular Reproduction and Development, 2008Co-Authors: Noriko Nakamura, Chisato Mori, Deborah A Obrien, Haruna Shibata, E M EddyAbstract:Hexokinase is the first enzyme in the glycolytic pathway and utilizes ATP to convert glucose to glucose-6-phosphate (G6P). We previously identified three variant transcripts of HK1 that are expressed specifically in spermatogenic cells, have different 5' untranslated regions, and encode a protein (HK1S, spermatogenic cell-specific type 1 hexokinase) in which the porin-binding domain (PBD) of HK1 is replaced by a novel N-terminal spermatogenic cell-specific region (SSR). However, the level of expression of the individual variant transcripts or of the other members of the hexokinase gene family (Hk2, Hk3, and Gck) in spermatogenic cells remains uncertain. We show that HK1, Hk2, and Hk3 transcripts levels are quite low in spermatocytes and spermatids and Gck transcripts are relatively abundant in spermatids, but that glucokinase (GCK) is not detected in spermatozoa. Using real time RT-PCR (qPCR) with primers specific for each of the three variant forms and RNA from whole testis and isolated germ cells, we found that transcripts for HK1_v2 and HK1_v3, but not for HK1_v1, are relatively high in spermatids. Similar results were seen using spermatogenic cells isolated by laser-capture microdissection (LCM). Immunoblotting studies found that HK1S is abundant in sperm, and immunostaining confirmed that HK1S is located mainly in the principal piece of the sperm flagellum, where other spermatogenic cell-specific glycolytic enzymes have been found. These results strongly suggest that HK1, HK2, HK3, and GCK are unlikely to have a role in glycolysis in sperm and that HK1S encoded by HK1_v2 and HK1_v3 serves this role.
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mouse spermatogenic cell specific type 1 hexokinase mHK1 s transcripts are expressed by alternative splicing from the mHK1 gene and the HK1 s protein is localized mainly in the sperm tail
Molecular Reproduction and Development, 1998Co-Authors: Chisato Mori, J E Welch, Noriko Nakamura, Hideo Gotoh, Eugenia H Goulding, Makio Fujioka, E M EddyAbstract:Unique type 1 hexokinase (HK1) mRNAs are present in mouse spermatogenic cells (mHK1-s). They encode a spermatogenic cell-specific sequence region (SSR) but not the porin-binding domain (PBD) necessary for HK1 binding to porin on the outer mitochondrial membrane. This study determined the origin of the multiple HK1-s transcripts in mouse spermatogenic cells and verified that they are translated in mouse spermatogenic cells. It also showed that a single mHK1 gene encodes the mHK1 transcripts of somatic cells and the mHK1-sa and mHK1-sb transcripts of spermatogenic cells, that alternative exons are used during mHK1 gene expression in mouse spermatogenic cells, and that mHK1-S is translated in mouse spermatogenic cells and is localized mainly with the fibrous sheath in the tail region, not with the mitochondria in the midpiece of mouse sperm.
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unique hexokinase messenger ribonucleic acids lacking the porin binding domain are developmentally expressed in mouse spermatogenic cells
Biology of Reproduction, 1993Co-Authors: Chisato Mori, J E Welch, Kerry D Fulcher, Deborah A Obrien, E M EddyAbstract:We have identified cDNAs representing three hexokinase mRNAs (HK1-sa, HK1-sb, HK1-sc) by screening mouse spermatogenic cell cDNA libraries with a mouse hepatoma cell line hexokinase (HK1) cDNA [Arora KK, Fanciulli M, Pederson PL. J Biol Chem 1990; 265:6481-6488]. Although all three cDNAs show 99% identity to the somatic HK1 cDNA sequence throughout most of their coding region, they differ from this sequence at the 5' end. They contain a common spermatogenic cell-specific sequence and a sequence unique to each cDNA immediately 5' to the common domain. However, they lack the porin-binding domain (PBD) present in this region of HK1, used for binding to a pore-forming protein in the outer mitochondrial membrane. These observations appear to support a model proposed by others for hexokinase gene evolution in mammals. In addition, we found that HK1-sb has an internal sequence that is not present in HK1, HK1-sa, or HK1-sc. Moreover, HK1-sa and HK1-sb transcripts are developmentally expressed in mouse spermatogenic cells. HK1-sa mRNA is first expressed during meiosis and continues to be present in postmeiotic germ cells, while the more abundant HK1-sb mRNA is detected only in postmeiotic germ cells. These and other findings suggest that enzymes encoded by HK1-sa, HK1-sb, and HK1-sc are present only in spermatogenic cells.
Shili Xu - One of the best experts on this subject based on the ideXlab platform.
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a tumor agnostic therapeutic strategy for hexokinase 1 null hexokinase 2 positive cancers
Cancer Research, 2019Co-Authors: Shili Xu, Harvey R. HerschmanAbstract:Since Warburg9s observation that most cancers exhibit elevated glycolysis, decades of research have attempted to reduce tumor glucose utilization as a therapeutic approach. Hexokinase (HK) activity is the first glycolytic enzymatic step; despite many attempts to inhibit HK activity, none has reached clinical application. Identification of HK isoforms, and recognition that most tissues express only HK1 while most tumors express HK1 and HK2, stimulated reducing HK2 activity as a therapeutic option. However, studies using HK2 shRNA and isogenic HK1+HK2- and HK1+HK2+ tumor cell pairs demonstrated that tumors expressing only HK1, while exhibiting reduced glucose consumption, progressed in vivo as well as tumors expressing both HK1 and HK2. However, there exist HK1-HK2+ tumor subpopulations among many cancers. shRNA HK2 suppression in HK1-HK2+ liver cancer cells reduced xenograft tumor progression, in contrast to HK1+HK2+ cells. HK2 Inhibition, and partial inhibition of both oxidative phosphorylation and fatty acid oxidation using HK2 shRNA and small molecule drugs, prevented human liver HK1-HK2+ cancer xenograft progression. Using human multiple myeloma xenografts and mouse allogeneic models to identify potential clinical translational agents, triple therapies that include antisense HK2 oligonucleotides, metformin and perhexiline prevent progression. These results suggest an agnostic approach for HK1-HK2+ cancers, regardless of tissue origin.
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an hk2 antisense oligonucleotide induces synthetic lethality in HK1 hk2 multiple myeloma
Cancer Research, 2019Co-Authors: Shili Xu, Arthur Catapang, Nicholas A Bayley, Reiko E Yamada, Alex Vasuthasawat, Joshua Sasine, Tianyuan Zhou, Daniel Braas, Ryan K. Trinh, John M TimmermanAbstract:Although the majority of adult tissues express only hexokinase 1 (HK1) for glycolysis, most cancers express hexokinase 2 (HK2) and many coexpress HK1 and HK2. In contrast to HK1+HK2+ cancers, HK1−HK2+ cancer subsets are sensitive to cytostasis induced by HK2shRNA knockdown and are also sensitive to synthetic lethality in response to the combination of HK2shRNA knockdown, an oxidative phosphorylation (OXPHOS) inhibitor diphenyleneiodonium (DPI), and a fatty acid oxidation (FAO) inhibitor perhexiline (PER). The majority of human multiple myeloma cell lines are HK1−HK2+. Here we describe an antisense oligonucleotide (ASO) directed against human HK2 (HK2-ASO1), which suppressed HK2 expression in human multiple myeloma cell cultures and human multiple myeloma mouse xenograft models. The HK2-ASO1/DPI/PER triple-combination achieved synthetic lethality in multiple myeloma cells in culture and prevented HK1−HK2+ multiple myeloma tumor xenograft progression. DPI was replaceable by the FDA-approved OXPHOS inhibitor metformin (MET), both for synthetic lethality in culture and for inhibition of tumor xenograft progression. In addition, we used an ASO targeting murine HK2 (mHK2-ASO1) to validate the safety of mHK2-ASO1/MET/PER combination therapy in mice bearing murine multiple myeloma tumors. HK2-ASO1 is the first agent that shows selective HK2 inhibition and therapeutic efficacy in cell culture and in animal models, supporting clinical development of this synthetically lethal combination as a therapy for HK1−HK2+ multiple myeloma. Significance: A first-in-class HK2 antisense oligonucleotide suppresses HK2 expression in cell culture and in in vivo, presenting an effective, tolerated combination therapy for preventing progression of HK1−HK2+ multiple myeloma tumors. Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/10/2748/F1.large.jpg.
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an hk2 antisense oligonucleotide induces synthetic lethality in HK1 hk2 multiple myeloma
Cancer Research, 2019Co-Authors: Shili Xu, Arthur Catapang, Nicholas A Bayley, Reiko E Yamada, Alex Vasuthasawat, Joshua Sasine, Tianyuan Zhou, Daniel Braas, Ryan K. Trinh, John M TimmermanAbstract:Although the majority of adult tissues express only hexokinase 1 (HK1) for glycolysis, most cancers express hexokinase 2 (HK2) and many coexpress HK1 and HK2. In contrast to HK1+HK2+ cancers, HK1−HK2+ cancer subsets are sensitive to cytostasis induced by HK2shRNA knockdown and are also sensitive to synthetic lethality in response to the combination of HK2shRNA knockdown, an oxidative phosphorylation (OXPHOS) inhibitor diphenyleneiodonium (DPI), and a fatty acid oxidation (FAO) inhibitor perhexiline (PER). The majority of human multiple myeloma cell lines are HK1−HK2+. Here we describe an antisense oligonucleotide (ASO) directed against human HK2 (HK2-ASO1), which suppressed HK2 expression in human multiple myeloma cell cultures and human multiple myeloma mouse xenograft models. The HK2-ASO1/DPI/PER triple-combination achieved synthetic lethality in multiple myeloma cells in culture and prevented HK1−HK2+ multiple myeloma tumor xenograft progression. DPI was replaceable by the FDA-approved OXPHOS inhibitor metformin (MET), both for synthetic lethality in culture and for inhibition of tumor xenograft progression. In addition, we used an ASO targeting murine HK2 (mHK2-ASO1) to validate the safety of mHK2-ASO1/MET/PER combination therapy in mice bearing murine multiple myeloma tumors. HK2-ASO1 is the first agent that shows selective HK2 inhibition and therapeutic efficacy in cell culture and in animal models, supporting clinical development of this synthetically lethal combination as a therapy for HK1−HK2+ multiple myeloma. Significance: A first-in-class HK2 antisense oligonucleotide suppresses HK2 expression in cell culture and in in vivo, presenting an effective, tolerated combination therapy for preventing progression of HK1−HK2+ multiple myeloma tumors. Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/10/2748/F1.large.jpg.
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hexokinase 2 is targetable for HK1 negative hk2 positive tumors from a wide variety of tissues of origin
The Journal of Nuclear Medicine, 2019Co-Authors: Shili Xu, Arthur Catapang, Thomas G Graeber, Nicholas A Bayley, Daniel Braas, Harvey R. HerschmanAbstract:: Although absent in most adult tissues, hexokinase 2 (HK2) is expressed in a majority of tumors and contributes to increased glucose consumption and to in vivo tumor 18F-FDG PET signaling. Methods: Both HK2 knockdown and knockout approaches were used to investigate the role of HK2 in cancer cell proliferation, in vivo xenograft tumor progression and 18F-FDG tumor accumulation. BioProfiler analysis monitored cell culture glucose consumption and lactate production; 18F-FDG PET/CT monitored in vivo tumor glucose accumulation. Cancer Cell Line Encyclopedia data were analyzed for HK1 and HK2 expression. Results: Neither cell proliferation in culture nor xenograft tumor progression are inhibited by HK2 knockdown or knockout in cancer cells that express HK1 and HK2. However, cancer subsets from a variety of tissues of origin express only HK2, but not HK1. In contrast to HK1+HK2+ cancers, HK2 knockdown in HK1-HK2+ cancer cells results in inhibition of cell proliferation, colony formation and xenograft tumor progression. Moreover, HK1KOHK2+ cancer cells are susceptible to HK2 inhibition, in contrast to their isogenic HK1+HK2+ parental cells. Conclusion: HK1 and HK2 expression are redundant in tumors; either can provide sufficient aerobic glycolysis for tumor growth; despite a reduction in 18F-FDG PET signal. Therapeutic HK2 inhibition is likely to be restricted to HK1-HK2+ tumor subsets, but stratification of tumors that express HK2, but not HK1, should identify tumors treatable with emerging HK2 specific inhibitors.
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hexokinase 2 is targetable for HK1 negative hk2 positive tumors from a wide variety of tissues of origin
The Journal of Nuclear Medicine, 2019Co-Authors: Shili Xu, Arthur Catapang, Thomas G Graeber, Nicholas A Bayley, Daniel Braas, Harvey R. HerschmanAbstract:: Although absent in most adult tissues, hexokinase 2 (HK2) is expressed in a majority of tumors and contributes to increased glucose consumption and to in vivo tumor 18F-FDG PET signaling. Methods: Both HK2 knockdown and knockout approaches were used to investigate the role of HK2 in cancer cell proliferation, in vivo xenograft tumor progression and 18F-FDG tumor accumulation. BioProfiler analysis monitored cell culture glucose consumption and lactate production; 18F-FDG PET/CT monitored in vivo tumor glucose accumulation. Cancer Cell Line Encyclopedia data were analyzed for HK1 and HK2 expression. Results: Neither cell proliferation in culture nor xenograft tumor progression are inhibited by HK2 knockdown or knockout in cancer cells that express HK1 and HK2. However, cancer subsets from a variety of tissues of origin express only HK2, but not HK1. In contrast to HK1+HK2+ cancers, HK2 knockdown in HK1-HK2+ cancer cells results in inhibition of cell proliferation, colony formation and xenograft tumor progression. Moreover, HK1KOHK2+ cancer cells are susceptible to HK2 inhibition, in contrast to their isogenic HK1+HK2+ parental cells. Conclusion: HK1 and HK2 expression are redundant in tumors; either can provide sufficient aerobic glycolysis for tumor growth; despite a reduction in 18F-FDG PET signal. Therapeutic HK2 inhibition is likely to be restricted to HK1-HK2+ tumor subsets, but stratification of tumors that express HK2, but not HK1, should identify tumors treatable with emerging HK2 specific inhibitors.