Metabolic reprogramming is a hallmark of many cancer types, including hepatocellular carcinoma (H... more Metabolic reprogramming is a hallmark of many cancer types, including hepatocellular carcinoma (HCC). Identifying the critical players in this process might be crucial for the generation of novel and effective anti-neoplastic therapies. In the present investigation, we determined the importance of carbohydrate responsive element binding protein (ChREBP), a central player in the regulation of lipid and glucose metabolism in the liver, on the development of HCC in in vitro and in vivo models. We found that genetic deletion of ChREBP (that will be referred to as ChREBPKO mice) strongly delays or impairs hepatocarcinogenesis driven by AKT or AKT/c-Met overexpression in mice, respectively. In contrast, HCC development was found to be completely unaffected by ChREBP depletion in mice co-expressing AKT and N-Ras protooncogenes. In mouse and human HCC cell lines, suppression of ChREBP via specific small interfering RNAs (siRNAs) resulted in decreased proliferation and induction of apoptosis. Of note, these cellular events were strongly augmented by concomitant inhibition of the mitogen-activated protein kinase (MAPK) pathway. The present data indicate that ChREBP activity might be required or dispensable for HCC growth, depending on the oncogenes involved. In particular, the activation of Ras/MAPK signaling might represent a possible mechanism of resistance to ChREBP depletion in this tumor type. Additional studies are needed to unravel the molecular mechanisms rendering HCC cells insensitive to ChREBP suppression.
The p53 tumor suppressor coordinates a series of antiproliferative responses that restrict the ex... more The p53 tumor suppressor coordinates a series of antiproliferative responses that restrict the expansion of malignant cells, and as a consequence, p53 is lost or mutated in the majority of human cancers. Here, we show that p53 restricts expression of the stem and progenitor-cell-associated protein nestin in an Sp1/3 transcription-factor-dependent manner and that Nestin is required for tumor initiation in vivo. Moreover, loss of p53 facilitates dedifferentiation of mature hepatocytes into nestin-positive progenitor-like cells, which are poised to differentiate into hepatocellular carcinomas (HCCs) or cholangiocarcinomas (CCs) in response to lineage-specific mutations that target Wnt and Notch signaling, respectively. Many human HCCs and CCs show elevated nestin expression, which correlates with p53 loss of function and is associated with decreased patient survival. Therefore, transcriptional repression of Nestin by p53 restricts cellular plasticity and tumorigenesis in liver cancer.
World journal of gastroenterology : WJG, Jan 28, 2015
In this review we focus on lymphoepithelioma-like hepatocellular carcinomas (LEL-HCC) and lymphoe... more In this review we focus on lymphoepithelioma-like hepatocellular carcinomas (LEL-HCC) and lymphoepithelioma-like cholangiocarcinomas (LEL-ICC). Despite their rarity, these tumors are of general interest because of their epidemiological and clinical features, and because they represent a distinct model of interaction between the immune system and neoplastic cells. Approximately half of LEL-HCC arise in the context of chronic hepatitis C virus (HCV) infection and have been described both in Eastern and Western patients. By contrast, LEL-ICC is associated in almost all cases with Epstein-Barr virus (EBV) infection and exhibits the same epidemiological features of EBV related malignancies. Compared with classical hepatocellular carcinoma and intrahepatic cholangiocarcinoma of corresponding stage, both LEL-HCC and LEL-ICC are characterized by lower rates of recurrence after surgery and better overall survival. How this behavior is related to distinct genetic alterations and tumor microen...
Previous work from our laboratory has implicated oxidative DNA damage and genetic instability in ... more Previous work from our laboratory has implicated oxidative DNA damage and genetic instability in the etiology of transforming growth factor-␣ (TGF␣)/c-myc-associated hepatocarcinogenesis. In contrast, oxidative DNA damage was lower in c-myc single-transgenic mice, consistent with less chromosomal damage and with later and more benign tumor formation. We examined whether defects in the DNA repair pathways contribute to the acceleration of liver cancer in TGF␣/c-myc mice. A cDNA expression array containing 140 known genes and multiplex RT-PCR were used to compare the basal levels of expression of DNA repair genes at the dysplastic stage. Thirty-five percent (8/23) and 43% (10/23) of DNA repair genes were constitutively up-regulated in 10-week-old TGF␣/c-myc and c-myc transgenic livers, respectively, compared with wild-type controls. The commonly up-regulated genes were OGG1 and NTH1 of base excision repair; ERCC5, RAD23A, and RAD23B of nucleotide excision repair; and RAD50, RAD52, and RAD54 involved in DNA strand break repair. Additional treatment with a peroxisome proliferator, Wy-14,643, known to increase the level of oxidants in the liver, failed to induce a further increase in the expression level of DNA repair enzymes in TGF␣/c-myc but not in c-myc or wild-type livers. Moreover, expression of several genes, including Ku80, PMS2, and ATM, was decreased in TGF␣/c-myc livers, suggesting a fault or inefficient activation of the DNA repair pathway upon induction of oxidative stress. Together, the results show that DNA damage response is attenuated in TGF␣/c-myc mice, creating a condition that may contribute to acceleration of liver cancer in this model. (Lab Invest 2003, 83:643-654).
Referate Preisträger: Rudolf-Virchow-Preisträger 2011 Die gestörte Lipidbiosynthese (üblicherweis... more Referate Preisträger: Rudolf-Virchow-Preisträger 2011 Die gestörte Lipidbiosynthese (üblicherweise auch als "De-novo-Lipogenese" oder "De-novo-Lipidsynthese" bezeichnet) spielt eine wichtige pathogenetische Rolle bei der Entstehung verschiedener metabolischer Erkrankungen, wie dem Diabetes mellitus, der Adipositas und dem metabolischen Syndrom, aber auch bei Tumorerkrankungen. Tumorzellen synthetisieren de novo große Mengen von Fettsäuren und Cholesterol, unabhängig von den im Blut zirkulierenden, zumeist von der Nahrung stammenden Lipiden und besitzen durch diese gesteigerte Lipidsynthese einen Wachstumsvorteil, ein verlängertes Überleben und eine Resistenz gegenüber medikamentöser Beeinflussung. Der Beitrag einer gestörten Lipogenese zur Entwicklung des hepatozellulären Karzinoms (HCC) und seiner Progression ebenso wie die molekularen Mechanismen, die zu dieser aberranten Lipidbiosynthese beitragen, wird zunehmend besser verstanden.
Abbreviations used in this paper: AMPK, 5=-adenosine monophosphate-activated protein kinase; CaMK... more Abbreviations used in this paper: AMPK, 5=-adenosine monophosphate-activated protein kinase; CaMKK, Ca 2؉ /calmodulin-dependent protein kinase kinase; DNMT, DNA methyltransferase; GNMT, glycine N-methyltransferase; GTP, guanosine triphosphate; KO, knockout; LKB1, liver kinase B1; MAT, methionine adenosyltransferase; PKA, protein kinase A; SAMe, S-adenosylmethionine; siRNA, small interfering RNA; WT, wild-type.
Archives of Physiology and Biochemistry, May 1, 2009
Epidemiological studies assign a role to insulin signalling deregulation and diabetes mellitus in... more Epidemiological studies assign a role to insulin signalling deregulation and diabetes mellitus in human hepatocarcinogenesis. The underlying mechanisms, however, remain largely unknown. To unravel the molecular pathogenesis of insulin-induced hepatocarcinogenesis, we generated an experimental animal model: after transplantation of only a low number of isologous pancreatic islets into the livers of diabetic rats, mild diabetes persists and the beta cells are maximally stimulated to permanently secrete insulin. As a consequence, liver acini, draining the hyperinsulinemic blood from islet grafts, show insulin-induced adaptive alterations simultaneously resembling preneoplastic foci of chemically-induced hepatocarcinogenesis models. These lesions progress to hepatocellular tumours within 6 and 24 months. Hepatocarcinogenesis is accompanied by alterations in hepatocytes metabolisms and changes in signal transduction pathways that, in the beginning, can be attributed solely to insulin action. In this review, we summarize our findings that may help understanding the oncogenic potential of diabetes mellitus in the human liver.
Activation of the AKT/mTOR cascade and overexpression of c-Met have been implicated in the develo... more Activation of the AKT/mTOR cascade and overexpression of c-Met have been implicated in the development of human hepatocellular carcinoma (HCC). To elucidate the functional crosstalk between the two pathways, we generated a model characterized by the combined expression of activated AKT and c-Met in the mouse liver. Co-expression of AKT and c-Met triggered rapid liver tumor development and mice required to be euthanized within 8 weeks after hydrodynamic injection. At the molecular level, liver tumors induced by AKT/c-Met display activation of AKT/mTOR and Ras/MAPK cascades as well as increased lipogenesis and glycolysis. Since a remarkable lipogenic phenotype characterizes liver lesions from AKT/c-Met mice, we determined the requirement of lipogenesis in AKT/c-Met driven hepatocarcinogenesis using conditional Fatty Acid Synthase (FASN) knockout mice. Of note, hepatocarcinogenesis induced by AKT/c-Met was fully inhibited by FASN ablation. In human HCC samples, coordinated expression o...
Human sporadic CCT were examined in a collection of 324 nephrectomy specimen, in terms of morphol... more Human sporadic CCT were examined in a collection of 324 nephrectomy specimen, in terms of morphologic, metabolic and molecular alterations, and compared to preneoplastic CCT and RCC developed in the rat following streptozotocin-induced diabetes or N-Nitrosomorpholine administration. Diabetic and non-diabetic rats were subjected to the dual PI3K/mTOR inhibitor, NVP/BEZ235. Human sporadic CCT could be detected in 17.3% of kidney specimens. Human and rat renal CCT display a strong induction of the PI3K/AKT/mTOR pathway and related metabolic alterations. Proteins involved in glycolysis and de novo lipogenesis were upregulated. In in vivo experiments, dual inhibition of PI3K and mTOR resulted in a reduction of proliferation of rat diabetes related CCT and increased autophagic activity.
Neoplastic liver nodules and hepatocellular carcinomas (HCCs) were induced, by "resistant hepatoc... more Neoplastic liver nodules and hepatocellular carcinomas (HCCs) were induced, by "resistant hepatocyte" model, 32 and 70 weeks after initiation with diethylnitrosamine, respectively, in F344 Brown Norway (BN), and (BNxF344)Fl rats. Nodule number/liver (N) did not significantly differ among rat strains, whereas nodule mean volume (V) and nodule volume fraction (VF) were higher in susceptible F344 than in resistant BN and BFF1 strains and were predictive of subsequent development of HCCs. Genomic scanning of 157 backcross BFFlxF344 rats with 190 polymorphic microsatellites, and linkage analysis, revealed two quantitative trait loci (QTL) on chromosomes 7 and 10, which showed significant linkage with VF, and two QTL on chromosomes 4 and 8, which showed suggestive linkage with V and VF. On the basis of phenotypic patterns of homozygous and heterozygous backcross progeny and of allelic distribution pattern, QTL on chromosomes 10, 8, and 4 were tentatively identified as resistance loci, and QTL on chromosome 7 was identified as susceptibility locus for rat hepatocarcinogenesis. An analysis of interactions allowed us to identify additional putative QTL on chromosomes 5 and 8 and suggested an additive effect of loci on chromosomes 10, 8, and 4 for VF and V. These data are the first to identify chromosomal regions containing putative susceptibility/resistance loci for rat hepatocarcinogenesis, which seems to be highly complex in terms of the number of genetic factors involved.
Mutation in one of three RAS genes (i.e., HRAS, KRAS, and NRAS) leading to constitutive activatio... more Mutation in one of three RAS genes (i.e., HRAS, KRAS, and NRAS) leading to constitutive activation of RAS signaling pathways is considered a key oncogenic event in human carcinogenesis. Whether activated RAS isoforms possess different oncogenic potentials remains an unresolved question. Here, we compared oncogenic properties among RAS isoforms using liver-specific transgenesis in mice. Hydrodynamic transfection was performed using transposons expressing short hairpin RNA downregulating p53 and an activated RAS isoform, and livers were harvested at 23 days after gene delivery. No differences were found in the hepatocarcinogenic potential among RAS isoforms, as determined by both gross examination of livers and liver weight per body weight ratio (LW/BW) of mice expressing HRASQ61L, KRAS4BG12V and NRASQ61K. However, the tumorigenic potential differed significantly between KRAS splicing variants. The LW/BW ratio in KRAS4AG12V mice was significantly lower than in KRAS4BG12V mice (p < ...
Liver international : official journal of the International Association for the Study of the Liver, Jan 30, 2015
Activating mutations of PIK3CA occur in various tumor types, including human hepatocellular carci... more Activating mutations of PIK3CA occur in various tumor types, including human hepatocellular carcinoma. The mechanisms whereby PIK3CA contributes to hepatocarcinogenesis remain poorly understood. PIK3CA mutants H1047R or E545K were hydrodynamically transfected, either alone or in combination with NRasV12 or c-Met genes, in the mouse liver. Overexpression of H1047R or E545K alone was able to induce AKT/mTOR signaling in the mouse liver, leading to hepatic steatosis. However, none of the mice developed liver tumors over long term. In contrast, H1047R or E545K cooperated with NRasV12 or c-Met rapidly induce liver tumor formation in mice. At the molecular level, all the tumor nodules displayed activation of AKT/mTOR and Ras/MAPK cascades. Ablation of AKT2 significantly inhibited hepatic steatosis induced by H1047R or E545K and carcinogenesis induced by H1047R/c-Met or E545K/c-Met. Furthermore, tumorigenesis induced by H1047R/c-Met was abolished in conditional Raptor knockout mice. In con...
Loss of heterozygosity (LOH) at specific chromosomal regions is a frequent event in poorly differ... more Loss of heterozygosity (LOH) at specific chromosomal regions is a frequent event in poorly differentiated human hepatocellular carcinomas (HCCs), but rare in mouse HCCs. This behavior could depend on interspecies differences in mechanisms of hepatocarcinogenesis or in developmental stage of lesions. To verify if LOH is involved in rat hepatocarcinogenesis, we studied LOH frequency in slowly growing neoplastic nodules induced by Solt-Farber model in diethylnitrosamine-initiated BFF1 rats. We analyzed, with microsatellites, markers at 67 rat loci dispersed over all chromosomes, corresponding to regions homologous to those lost in human HCCs or containing hepatocellular susceptibility (Hcs) or resistance (Hcr) loci in rat and mouse. In agreement with previous findings with mouse HCCs, but at variance with human HCCs, no detectable LOH was found at any locus in rats, suggesting rare LOH involvement in neoplastic nodules, with low tendency to progress to full malignancy, of BFF1 rats.
Metabolic reprogramming is a hallmark of many cancer types, including hepatocellular carcinoma (H... more Metabolic reprogramming is a hallmark of many cancer types, including hepatocellular carcinoma (HCC). Identifying the critical players in this process might be crucial for the generation of novel and effective anti-neoplastic therapies. In the present investigation, we determined the importance of carbohydrate responsive element binding protein (ChREBP), a central player in the regulation of lipid and glucose metabolism in the liver, on the development of HCC in in vitro and in vivo models. We found that genetic deletion of ChREBP (that will be referred to as ChREBPKO mice) strongly delays or impairs hepatocarcinogenesis driven by AKT or AKT/c-Met overexpression in mice, respectively. In contrast, HCC development was found to be completely unaffected by ChREBP depletion in mice co-expressing AKT and N-Ras protooncogenes. In mouse and human HCC cell lines, suppression of ChREBP via specific small interfering RNAs (siRNAs) resulted in decreased proliferation and induction of apoptosis. Of note, these cellular events were strongly augmented by concomitant inhibition of the mitogen-activated protein kinase (MAPK) pathway. The present data indicate that ChREBP activity might be required or dispensable for HCC growth, depending on the oncogenes involved. In particular, the activation of Ras/MAPK signaling might represent a possible mechanism of resistance to ChREBP depletion in this tumor type. Additional studies are needed to unravel the molecular mechanisms rendering HCC cells insensitive to ChREBP suppression.
The p53 tumor suppressor coordinates a series of antiproliferative responses that restrict the ex... more The p53 tumor suppressor coordinates a series of antiproliferative responses that restrict the expansion of malignant cells, and as a consequence, p53 is lost or mutated in the majority of human cancers. Here, we show that p53 restricts expression of the stem and progenitor-cell-associated protein nestin in an Sp1/3 transcription-factor-dependent manner and that Nestin is required for tumor initiation in vivo. Moreover, loss of p53 facilitates dedifferentiation of mature hepatocytes into nestin-positive progenitor-like cells, which are poised to differentiate into hepatocellular carcinomas (HCCs) or cholangiocarcinomas (CCs) in response to lineage-specific mutations that target Wnt and Notch signaling, respectively. Many human HCCs and CCs show elevated nestin expression, which correlates with p53 loss of function and is associated with decreased patient survival. Therefore, transcriptional repression of Nestin by p53 restricts cellular plasticity and tumorigenesis in liver cancer.
World journal of gastroenterology : WJG, Jan 28, 2015
In this review we focus on lymphoepithelioma-like hepatocellular carcinomas (LEL-HCC) and lymphoe... more In this review we focus on lymphoepithelioma-like hepatocellular carcinomas (LEL-HCC) and lymphoepithelioma-like cholangiocarcinomas (LEL-ICC). Despite their rarity, these tumors are of general interest because of their epidemiological and clinical features, and because they represent a distinct model of interaction between the immune system and neoplastic cells. Approximately half of LEL-HCC arise in the context of chronic hepatitis C virus (HCV) infection and have been described both in Eastern and Western patients. By contrast, LEL-ICC is associated in almost all cases with Epstein-Barr virus (EBV) infection and exhibits the same epidemiological features of EBV related malignancies. Compared with classical hepatocellular carcinoma and intrahepatic cholangiocarcinoma of corresponding stage, both LEL-HCC and LEL-ICC are characterized by lower rates of recurrence after surgery and better overall survival. How this behavior is related to distinct genetic alterations and tumor microen...
Previous work from our laboratory has implicated oxidative DNA damage and genetic instability in ... more Previous work from our laboratory has implicated oxidative DNA damage and genetic instability in the etiology of transforming growth factor-␣ (TGF␣)/c-myc-associated hepatocarcinogenesis. In contrast, oxidative DNA damage was lower in c-myc single-transgenic mice, consistent with less chromosomal damage and with later and more benign tumor formation. We examined whether defects in the DNA repair pathways contribute to the acceleration of liver cancer in TGF␣/c-myc mice. A cDNA expression array containing 140 known genes and multiplex RT-PCR were used to compare the basal levels of expression of DNA repair genes at the dysplastic stage. Thirty-five percent (8/23) and 43% (10/23) of DNA repair genes were constitutively up-regulated in 10-week-old TGF␣/c-myc and c-myc transgenic livers, respectively, compared with wild-type controls. The commonly up-regulated genes were OGG1 and NTH1 of base excision repair; ERCC5, RAD23A, and RAD23B of nucleotide excision repair; and RAD50, RAD52, and RAD54 involved in DNA strand break repair. Additional treatment with a peroxisome proliferator, Wy-14,643, known to increase the level of oxidants in the liver, failed to induce a further increase in the expression level of DNA repair enzymes in TGF␣/c-myc but not in c-myc or wild-type livers. Moreover, expression of several genes, including Ku80, PMS2, and ATM, was decreased in TGF␣/c-myc livers, suggesting a fault or inefficient activation of the DNA repair pathway upon induction of oxidative stress. Together, the results show that DNA damage response is attenuated in TGF␣/c-myc mice, creating a condition that may contribute to acceleration of liver cancer in this model. (Lab Invest 2003, 83:643-654).
Referate Preisträger: Rudolf-Virchow-Preisträger 2011 Die gestörte Lipidbiosynthese (üblicherweis... more Referate Preisträger: Rudolf-Virchow-Preisträger 2011 Die gestörte Lipidbiosynthese (üblicherweise auch als "De-novo-Lipogenese" oder "De-novo-Lipidsynthese" bezeichnet) spielt eine wichtige pathogenetische Rolle bei der Entstehung verschiedener metabolischer Erkrankungen, wie dem Diabetes mellitus, der Adipositas und dem metabolischen Syndrom, aber auch bei Tumorerkrankungen. Tumorzellen synthetisieren de novo große Mengen von Fettsäuren und Cholesterol, unabhängig von den im Blut zirkulierenden, zumeist von der Nahrung stammenden Lipiden und besitzen durch diese gesteigerte Lipidsynthese einen Wachstumsvorteil, ein verlängertes Überleben und eine Resistenz gegenüber medikamentöser Beeinflussung. Der Beitrag einer gestörten Lipogenese zur Entwicklung des hepatozellulären Karzinoms (HCC) und seiner Progression ebenso wie die molekularen Mechanismen, die zu dieser aberranten Lipidbiosynthese beitragen, wird zunehmend besser verstanden.
Abbreviations used in this paper: AMPK, 5=-adenosine monophosphate-activated protein kinase; CaMK... more Abbreviations used in this paper: AMPK, 5=-adenosine monophosphate-activated protein kinase; CaMKK, Ca 2؉ /calmodulin-dependent protein kinase kinase; DNMT, DNA methyltransferase; GNMT, glycine N-methyltransferase; GTP, guanosine triphosphate; KO, knockout; LKB1, liver kinase B1; MAT, methionine adenosyltransferase; PKA, protein kinase A; SAMe, S-adenosylmethionine; siRNA, small interfering RNA; WT, wild-type.
Archives of Physiology and Biochemistry, May 1, 2009
Epidemiological studies assign a role to insulin signalling deregulation and diabetes mellitus in... more Epidemiological studies assign a role to insulin signalling deregulation and diabetes mellitus in human hepatocarcinogenesis. The underlying mechanisms, however, remain largely unknown. To unravel the molecular pathogenesis of insulin-induced hepatocarcinogenesis, we generated an experimental animal model: after transplantation of only a low number of isologous pancreatic islets into the livers of diabetic rats, mild diabetes persists and the beta cells are maximally stimulated to permanently secrete insulin. As a consequence, liver acini, draining the hyperinsulinemic blood from islet grafts, show insulin-induced adaptive alterations simultaneously resembling preneoplastic foci of chemically-induced hepatocarcinogenesis models. These lesions progress to hepatocellular tumours within 6 and 24 months. Hepatocarcinogenesis is accompanied by alterations in hepatocytes metabolisms and changes in signal transduction pathways that, in the beginning, can be attributed solely to insulin action. In this review, we summarize our findings that may help understanding the oncogenic potential of diabetes mellitus in the human liver.
Activation of the AKT/mTOR cascade and overexpression of c-Met have been implicated in the develo... more Activation of the AKT/mTOR cascade and overexpression of c-Met have been implicated in the development of human hepatocellular carcinoma (HCC). To elucidate the functional crosstalk between the two pathways, we generated a model characterized by the combined expression of activated AKT and c-Met in the mouse liver. Co-expression of AKT and c-Met triggered rapid liver tumor development and mice required to be euthanized within 8 weeks after hydrodynamic injection. At the molecular level, liver tumors induced by AKT/c-Met display activation of AKT/mTOR and Ras/MAPK cascades as well as increased lipogenesis and glycolysis. Since a remarkable lipogenic phenotype characterizes liver lesions from AKT/c-Met mice, we determined the requirement of lipogenesis in AKT/c-Met driven hepatocarcinogenesis using conditional Fatty Acid Synthase (FASN) knockout mice. Of note, hepatocarcinogenesis induced by AKT/c-Met was fully inhibited by FASN ablation. In human HCC samples, coordinated expression o...
Human sporadic CCT were examined in a collection of 324 nephrectomy specimen, in terms of morphol... more Human sporadic CCT were examined in a collection of 324 nephrectomy specimen, in terms of morphologic, metabolic and molecular alterations, and compared to preneoplastic CCT and RCC developed in the rat following streptozotocin-induced diabetes or N-Nitrosomorpholine administration. Diabetic and non-diabetic rats were subjected to the dual PI3K/mTOR inhibitor, NVP/BEZ235. Human sporadic CCT could be detected in 17.3% of kidney specimens. Human and rat renal CCT display a strong induction of the PI3K/AKT/mTOR pathway and related metabolic alterations. Proteins involved in glycolysis and de novo lipogenesis were upregulated. In in vivo experiments, dual inhibition of PI3K and mTOR resulted in a reduction of proliferation of rat diabetes related CCT and increased autophagic activity.
Neoplastic liver nodules and hepatocellular carcinomas (HCCs) were induced, by "resistant hepatoc... more Neoplastic liver nodules and hepatocellular carcinomas (HCCs) were induced, by "resistant hepatocyte" model, 32 and 70 weeks after initiation with diethylnitrosamine, respectively, in F344 Brown Norway (BN), and (BNxF344)Fl rats. Nodule number/liver (N) did not significantly differ among rat strains, whereas nodule mean volume (V) and nodule volume fraction (VF) were higher in susceptible F344 than in resistant BN and BFF1 strains and were predictive of subsequent development of HCCs. Genomic scanning of 157 backcross BFFlxF344 rats with 190 polymorphic microsatellites, and linkage analysis, revealed two quantitative trait loci (QTL) on chromosomes 7 and 10, which showed significant linkage with VF, and two QTL on chromosomes 4 and 8, which showed suggestive linkage with V and VF. On the basis of phenotypic patterns of homozygous and heterozygous backcross progeny and of allelic distribution pattern, QTL on chromosomes 10, 8, and 4 were tentatively identified as resistance loci, and QTL on chromosome 7 was identified as susceptibility locus for rat hepatocarcinogenesis. An analysis of interactions allowed us to identify additional putative QTL on chromosomes 5 and 8 and suggested an additive effect of loci on chromosomes 10, 8, and 4 for VF and V. These data are the first to identify chromosomal regions containing putative susceptibility/resistance loci for rat hepatocarcinogenesis, which seems to be highly complex in terms of the number of genetic factors involved.
Mutation in one of three RAS genes (i.e., HRAS, KRAS, and NRAS) leading to constitutive activatio... more Mutation in one of three RAS genes (i.e., HRAS, KRAS, and NRAS) leading to constitutive activation of RAS signaling pathways is considered a key oncogenic event in human carcinogenesis. Whether activated RAS isoforms possess different oncogenic potentials remains an unresolved question. Here, we compared oncogenic properties among RAS isoforms using liver-specific transgenesis in mice. Hydrodynamic transfection was performed using transposons expressing short hairpin RNA downregulating p53 and an activated RAS isoform, and livers were harvested at 23 days after gene delivery. No differences were found in the hepatocarcinogenic potential among RAS isoforms, as determined by both gross examination of livers and liver weight per body weight ratio (LW/BW) of mice expressing HRASQ61L, KRAS4BG12V and NRASQ61K. However, the tumorigenic potential differed significantly between KRAS splicing variants. The LW/BW ratio in KRAS4AG12V mice was significantly lower than in KRAS4BG12V mice (p < ...
Liver international : official journal of the International Association for the Study of the Liver, Jan 30, 2015
Activating mutations of PIK3CA occur in various tumor types, including human hepatocellular carci... more Activating mutations of PIK3CA occur in various tumor types, including human hepatocellular carcinoma. The mechanisms whereby PIK3CA contributes to hepatocarcinogenesis remain poorly understood. PIK3CA mutants H1047R or E545K were hydrodynamically transfected, either alone or in combination with NRasV12 or c-Met genes, in the mouse liver. Overexpression of H1047R or E545K alone was able to induce AKT/mTOR signaling in the mouse liver, leading to hepatic steatosis. However, none of the mice developed liver tumors over long term. In contrast, H1047R or E545K cooperated with NRasV12 or c-Met rapidly induce liver tumor formation in mice. At the molecular level, all the tumor nodules displayed activation of AKT/mTOR and Ras/MAPK cascades. Ablation of AKT2 significantly inhibited hepatic steatosis induced by H1047R or E545K and carcinogenesis induced by H1047R/c-Met or E545K/c-Met. Furthermore, tumorigenesis induced by H1047R/c-Met was abolished in conditional Raptor knockout mice. In con...
Loss of heterozygosity (LOH) at specific chromosomal regions is a frequent event in poorly differ... more Loss of heterozygosity (LOH) at specific chromosomal regions is a frequent event in poorly differentiated human hepatocellular carcinomas (HCCs), but rare in mouse HCCs. This behavior could depend on interspecies differences in mechanisms of hepatocarcinogenesis or in developmental stage of lesions. To verify if LOH is involved in rat hepatocarcinogenesis, we studied LOH frequency in slowly growing neoplastic nodules induced by Solt-Farber model in diethylnitrosamine-initiated BFF1 rats. We analyzed, with microsatellites, markers at 67 rat loci dispersed over all chromosomes, corresponding to regions homologous to those lost in human HCCs or containing hepatocellular susceptibility (Hcs) or resistance (Hcr) loci in rat and mouse. In agreement with previous findings with mouse HCCs, but at variance with human HCCs, no detectable LOH was found at any locus in rats, suggesting rare LOH involvement in neoplastic nodules, with low tendency to progress to full malignancy, of BFF1 rats.
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Papers by Diego Calvisi