Reply to: “Deregulation of microRNAs expression occurs in stages of multistep hepatocarcinogenesis: Why is it different?”
Authors: Chun-Ming Wong, Irene Oi-Lin Ng
Journal: Journal of Hepatology (2012)

Deregulation of microRNAs expression occurs in stages of multistep hepatocarcinogenesis: Why is it different?Journal of HepatologyVol. 56Issue 6PreviewHBV is a major cause of acute and chronic liver infection, and can lead to hepatitis, cirrhosis, and hepatocellular carcinoma (HCC) [1], which is the fifth most common cancer and the third leading cause of cancer death worldwide. More than 80% of HCC patients are in developing countries, especially in Southeast Asia and sub-Saharan Africa. However, the incidence of HCC has been rising in Western countries in recent years [2]. The current standard of care and therapy for patients with advanced HCC are not satisfactory. Full-Text PDF Open AccessDeregulation of microRNA expression occurs early and accumulates in early stages of HBV-associated multistep hepatocarcinogenesisJournal of HepatologyVol. 54Issue 6PreviewDeregulation of microRNAs (miRNAs) plays an important role in human carcinogenesis. However, miRNA deregulation in the pre-malignant lesions and expression changes during multistep hepatocarcinogenesis remain elusive. Full-Text PDF Yin et al. drew attention to the differences between the findings on miR-221, miR-21 and miR-122 deregulation in hepatocarcinogenesis reported in our recent study [[1]Gao P. Wong C.C. Tung E.K. Lee J.M. Wong C.M. Ng I.O. Deregulation of microRNA expression occurs early and accumulates in early stages of HBV-associated multistep hepatocarcinogenesis.J Hepatol. 2011; 54: 1177-1184Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar] and others [2Connolly E. Melegari M. Landgraf P. Tchaikovskaya T. Tennant B.C. Slagle B.L. et al.Elevated expression of the miR-17-92 polycistron and miR-21 in hepadnavirus-associated hepatocellular carcinoma contributes to the malignant phenotype.Am J Pathol. 2008; 173: 856-864Abstract Full Text Full Text PDF PubMed Scopus (225) Google Scholar, 3Kutay H. Bai S. Datta J. Motiwala T. Pogribny I. Frankel W. et al.Downregulation of miR-122 in the rodent and human hepatocellular carcinomas.J Cell Biochem. 2006; 99: 671-678Crossref PubMed Scopus (530) Google Scholar, 4Pineau P. Volinia S. McJunkin K. Marchio A. Battiston C. Terris B. et al.MiR-221 overexpression contributes to liver tumorigenesis.Proc Natl Acad Sci U S A. 2010; 107: 264-269Crossref PubMed Scopus (637) Google Scholar]. Yin et al. further speculated that the inconsistence of the findings among these reports might be due to different risk factors for HCC and called for further investigations on this subject.In our article, we reported findings on the expression levels of seven cancer-related miRNAs in a series of chronic hepatitis/cirrhotic livers, dysplastic nodules (DNs) and small HCC samples. We found that miR-145, miR-199b and miR-224 were significantly deregulated in early stages of hepatocarcinogenesis (DN and small HCCs) when compared to the corresponding non-tumorous livers. The evidence for miR-21, miR-221, miR-10b and miR-122 deregulation was less clear and the data did not reach the stringent statistical threshold employed for that study (p <0.001 for one-way ANOVA and post tests with Bonferroni correction for multiple comparisons). However, we have to emphasize that our analysis mainly focused on the early stages of hepatocarcinogenesis and whether a miRNA was deregulated in DNs and small HCCs. Although our findings failed to demonstrate a statistically significant deregulation of miR-21, miR-221, miR-10b, and miR-122 in early stages of hepatocarcinogenesis, our findings in no way excluded the possibility of deregulation of these miRNAs in later stages of HCC. In fact, we found that miR-221 and miR-122 were significantly deregulated in early stages of HCCs when compared to the non-tumorous liver samples (p <0.001, post test with Bonferroni correction, Supplementary Fig. 1). An increasing trend was also observed with miR-21 when small HCCs were compared with the non-tumorous livers. These findings were actually in line with those of the previous reports [2Connolly E. Melegari M. Landgraf P. Tchaikovskaya T. Tennant B.C. Slagle B.L. et al.Elevated expression of the miR-17-92 polycistron and miR-21 in hepadnavirus-associated hepatocellular carcinoma contributes to the malignant phenotype.Am J Pathol. 2008; 173: 856-864Abstract Full Text Full Text PDF PubMed Scopus (225) Google Scholar, 3Kutay H. Bai S. Datta J. Motiwala T. Pogribny I. Frankel W. et al.Downregulation of miR-122 in the rodent and human hepatocellular carcinomas.J Cell Biochem. 2006; 99: 671-678Crossref PubMed Scopus (530) Google Scholar, 4Pineau P. Volinia S. McJunkin K. Marchio A. Battiston C. Terris B. et al.MiR-221 overexpression contributes to liver tumorigenesis.Proc Natl Acad Sci U S A. 2010; 107: 264-269Crossref PubMed Scopus (637) Google Scholar].In principle, we agree with Yin et al. that risk factors may affect the miRNA expression pattern in HCCs. In our study, we focused on the miRNA deregulation in HBV-associated HCC [[1]Gao P. Wong C.C. Tung E.K. Lee J.M. Wong C.M. Ng I.O. Deregulation of microRNA expression occurs early and accumulates in early stages of HBV-associated multistep hepatocarcinogenesis.J Hepatol. 2011; 54: 1177-1184Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar]. Indeed, the HCC samples used in the above-mentioned studies had substantially different etiological backgrounds when compared to our sample cohort. Kutay et al. mainly focused on pre-malignant nodules and HCC samples obtained from foliate and methyl-deficient (FMD) diet-fed Fisher 334 rats, while the risk factors of the three human HCC samples in their study were not described [[3]Kutay H. Bai S. Datta J. Motiwala T. Pogribny I. Frankel W. et al.Downregulation of miR-122 in the rodent and human hepatocellular carcinomas.J Cell Biochem. 2006; 99: 671-678Crossref PubMed Scopus (530) Google Scholar]. In the study of Pineau et al. the HCC samples were mainly (>75%) HCV-associated [[4]Pineau P. Volinia S. McJunkin K. Marchio A. Battiston C. Terris B. et al.MiR-221 overexpression contributes to liver tumorigenesis.Proc Natl Acad Sci U S A. 2010; 107: 264-269Crossref PubMed Scopus (637) Google Scholar], and the risk factor was different from that of our samples. For the 19 HCC samples used by Connolly et al., nine were HBsAg positive but the HBV status was not available in the remaining 10 cases. In addition, these HCC samples were collected from Qidong area of Jiangsu Province of China, where aflatoxin B1 is a common risk factor of HCC [[2]Connolly E. Melegari M. Landgraf P. Tchaikovskaya T. Tennant B.C. Slagle B.L. et al.Elevated expression of the miR-17-92 polycistron and miR-21 in hepadnavirus-associated hepatocellular carcinoma contributes to the malignant phenotype.Am J Pathol. 2008; 173: 856-864Abstract Full Text Full Text PDF PubMed Scopus (225) Google Scholar]. The diversity of the etiological background of the samples, together with the various experimental approaches involved, very much hinders direct comparison of data among the different studies. For this reason, experimentally unified and well controlled studies on large sample cohorts are required to investigate the effects of different etiological factors on miRNA deregulation in human HCCs.Conflict of interestThe authors declared that they do not have anything to disclose regarding funding or conflict of interest with respect to this manuscript. Yin et al. drew attention to the differences between the findings on miR-221, miR-21 and miR-122 deregulation in hepatocarcinogenesis reported in our recent study [[1]Gao P. Wong C.C. Tung E.K. Lee J.M. Wong C.M. Ng I.O. Deregulation of microRNA expression occurs early and accumulates in early stages of HBV-associated multistep hepatocarcinogenesis.J Hepatol. 2011; 54: 1177-1184Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar] and others [2Connolly E. Melegari M. Landgraf P. Tchaikovskaya T. Tennant B.C. Slagle B.L. et al.Elevated expression of the miR-17-92 polycistron and miR-21 in hepadnavirus-associated hepatocellular carcinoma contributes to the malignant phenotype.Am J Pathol. 2008; 173: 856-864Abstract Full Text Full Text PDF PubMed Scopus (225) Google Scholar, 3Kutay H. Bai S. Datta J. Motiwala T. Pogribny I. Frankel W. et al.Downregulation of miR-122 in the rodent and human hepatocellular carcinomas.J Cell Biochem. 2006; 99: 671-678Crossref PubMed Scopus (530) Google Scholar, 4Pineau P. Volinia S. McJunkin K. Marchio A. Battiston C. Terris B. et al.MiR-221 overexpression contributes to liver tumorigenesis.Proc Natl Acad Sci U S A. 2010; 107: 264-269Crossref PubMed Scopus (637) Google Scholar]. Yin et al. further speculated that the inconsistence of the findings among these reports might be due to different risk factors for HCC and called for further investigations on this subject. In our article, we reported findings on the expression levels of seven cancer-related miRNAs in a series of chronic hepatitis/cirrhotic livers, dysplastic nodules (DNs) and small HCC samples. We found that miR-145, miR-199b and miR-224 were significantly deregulated in early stages of hepatocarcinogenesis (DN and small HCCs) when compared to the corresponding non-tumorous livers. The evidence for miR-21, miR-221, miR-10b and miR-122 deregulation was less clear and the data did not reach the stringent statistical threshold employed for that study (p <0.001 for one-way ANOVA and post tests with Bonferroni correction for multiple comparisons). However, we have to emphasize that our analysis mainly focused on the early stages of hepatocarcinogenesis and whether a miRNA was deregulated in DNs and small HCCs. Although our findings failed to demonstrate a statistically significant deregulation of miR-21, miR-221, miR-10b, and miR-122 in early stages of hepatocarcinogenesis, our findings in no way excluded the possibility of deregulation of these miRNAs in later stages of HCC. In fact, we found that miR-221 and miR-122 were significantly deregulated in early stages of HCCs when compared to the non-tumorous liver samples (p <0.001, post test with Bonferroni correction, Supplementary Fig. 1). An increasing trend was also observed with miR-21 when small HCCs were compared with the non-tumorous livers. These findings were actually in line with those of the previous reports [2Connolly E. Melegari M. Landgraf P. Tchaikovskaya T. Tennant B.C. Slagle B.L. et al.Elevated expression of the miR-17-92 polycistron and miR-21 in hepadnavirus-associated hepatocellular carcinoma contributes to the malignant phenotype.Am J Pathol. 2008; 173: 856-864Abstract Full Text Full Text PDF PubMed Scopus (225) Google Scholar, 3Kutay H. Bai S. Datta J. Motiwala T. Pogribny I. Frankel W. et al.Downregulation of miR-122 in the rodent and human hepatocellular carcinomas.J Cell Biochem. 2006; 99: 671-678Crossref PubMed Scopus (530) Google Scholar, 4Pineau P. Volinia S. McJunkin K. Marchio A. Battiston C. Terris B. et al.MiR-221 overexpression contributes to liver tumorigenesis.Proc Natl Acad Sci U S A. 2010; 107: 264-269Crossref PubMed Scopus (637) Google Scholar]. In principle, we agree with Yin et al. that risk factors may affect the miRNA expression pattern in HCCs. In our study, we focused on the miRNA deregulation in HBV-associated HCC [[1]Gao P. Wong C.C. Tung E.K. Lee J.M. Wong C.M. Ng I.O. Deregulation of microRNA expression occurs early and accumulates in early stages of HBV-associated multistep hepatocarcinogenesis.J Hepatol. 2011; 54: 1177-1184Abstract Full Text Full Text PDF PubMed Scopus (124) Google Scholar]. Indeed, the HCC samples used in the above-mentioned studies had substantially different etiological backgrounds when compared to our sample cohort. Kutay et al. mainly focused on pre-malignant nodules and HCC samples obtained from foliate and methyl-deficient (FMD) diet-fed Fisher 334 rats, while the risk factors of the three human HCC samples in their study were not described [[3]Kutay H. Bai S. Datta J. Motiwala T. Pogribny I. Frankel W. et al.Downregulation of miR-122 in the rodent and human hepatocellular carcinomas.J Cell Biochem. 2006; 99: 671-678Crossref PubMed Scopus (530) Google Scholar]. In the study of Pineau et al. the HCC samples were mainly (>75%) HCV-associated [[4]Pineau P. Volinia S. McJunkin K. Marchio A. Battiston C. Terris B. et al.MiR-221 overexpression contributes to liver tumorigenesis.Proc Natl Acad Sci U S A. 2010; 107: 264-269Crossref PubMed Scopus (637) Google Scholar], and the risk factor was different from that of our samples. For the 19 HCC samples used by Connolly et al., nine were HBsAg positive but the HBV status was not available in the remaining 10 cases. In addition, these HCC samples were collected from Qidong area of Jiangsu Province of China, where aflatoxin B1 is a common risk factor of HCC [[2]Connolly E. Melegari M. Landgraf P. Tchaikovskaya T. Tennant B.C. Slagle B.L. et al.Elevated expression of the miR-17-92 polycistron and miR-21 in hepadnavirus-associated hepatocellular carcinoma contributes to the malignant phenotype.Am J Pathol. 2008; 173: 856-864Abstract Full Text Full Text PDF PubMed Scopus (225) Google Scholar]. The diversity of the etiological background of the samples, together with the various experimental approaches involved, very much hinders direct comparison of data among the different studies. For this reason, experimentally unified and well controlled studies on large sample cohorts are required to investigate the effects of different etiological factors on miRNA deregulation in human HCCs. Conflict of interestThe authors declared that they do not have anything to disclose regarding funding or conflict of interest with respect to this manuscript. The authors declared that they do not have anything to disclose regarding funding or conflict of interest with respect to this manuscript.