ABSTRACT

Telomerase is a key enzyme for cell survival that prevents telomere shortening and the subsequent cellular senescence that is observed after many rounds of cell division. In contrast, inactivation of telomerase is observed in most cells of the adult liver. Absence of telomerase activity and shortening of telomeres has been implicated in hepatocyte senescence and the development of cirrhosis, a chronic liver disease that can lead to hepatocellular carcinoma (HCC) development. During hepatocarcinogenesis, telomerase reactivation is required to enable the uncontrolled cell proliferation that leads to malignant transformation and HCC development. Part of the telomerase complex, telomerase reverse transcriptase, is encoded by TERT, and several mechanisms of telomerase reactivation have been described in HCC that include somatic TERT promoter mutations, TERTamplification, TERT translocation and viral insertion into the TERTgene. An understanding of the role of telomeres and telomerase in HCC development is important to develop future targeted therapies and improve survival of this disease. In this Review, the roles of telomeres and telomerase in liver carcinogenesis are discussed, in addition to their potential translation to clinical practice as biomarkers and therapeutic targets.

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The last work of Sandra Rebouissou group is newly accepted for publication in Gastroenterology.

Entitled, “Analysis of Liver Cancer Cell Lines Identifies Agents With Likely Efficacy Against Hepatocellular Carcinoma and Markers of Response” it is the first study to provide a comprehensive molecular characterization of most widely used liver cancer cell lines. All the data are available at : www.lccl.zucmanlab.com

Article available on Gastroenterology website.

Yuna Blum, from Ligue National Contre le Cancer and Didier Jean group used a deconvolution approach and show that molecular gradients shed new light on the intra-tumor heterogeneity of malignant mesothelioma.

Malignant pleural mesothelioma (MPM) is recognized as heterogeneous based both onhistology and molecular profiling. Histology addresses inter-tumor and intra-tumor hetero-geneity in MPM and describes three major types: epithelioid, sarcomatoid and biphasic, acombination of the former two types. Molecular profiling studies have not addressed intra-tumor heterogeneity in MPM to date. Here, we use a deconvolution approach and show thatmolecular gradients shed new light on the intra-tumor heterogeneity of MPM, leading to areconsideration of MPM molecular classifications. We show that each tumor can bedecomposed as a combination of epithelioid-like and sarcomatoid-like components whoseproportions are highly associated with the prognosis. Moreover, we show that this moresubtle way of characterizing MPM heterogeneity provides a better understanding of theunderlying oncogenic pathways and the related epigenetic regulation and immune andstromal contexts. We discuss the implications of thesefindings for guiding therapeuticstrategies, particularly immunotherapies and targeted therapies.

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In the team we promote the sharing of scientific data. That’s why now you can download the raw data from our latest publications directly on our website.

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Cyclin A2/E1 activation defines a hepatocellular carcinoma subclass with a rearrangement signature of replication stress

We are proud to share you our last publication in Nature Communications. Quentin Bayard from Eric Letouzé group identifies a new hepatocellular carcinoma subclass with a rearrangement signature of replication stress and defined by Cyclin A2/E1 activation.

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PNPLA3 and TM6SF2 variants as risk factors of hepatocellular carcinoma across various etiologies and severity of underlying liver diseases.

Few single nucleotide polymorphisms (SNPs) have been reproducibly associated with hepatocellular carcinoma (HCC). Our aim was to test the association between nine SNPs and HCC occurrence. SNPs in genes linked to HCC (DEPDC5, GRIK1, KIF1B, STAT4, MICA, DLC1, DDX18) or to liver damage (PNPLA3-rs738409, TM6SF2-rs58542926) in GWAS were genotyped in discovery cohorts including 1,020 HCC, 2,021 controls with chronic liver disease and 2,484 healthy individuals and replication was performed in prospective cohorts of cirrhotic patients with alcoholic liver disease (ALD, n = 249) and hepatitis C (n = 268). In the discovery cohort, PNPLA3 and TM6SF2 SNPs were associated with HCC (OR = 1.67 [CI95%:1.16-2.40], p = 0.005; OR = 1.45 [CI95%:1.08-1.94], p = 0.01) after adjustment for fibrosis, age, gender and etiology. In contrast, STAT4-rs7574865 was associated with HCC only in HBV infected patients (p = 0.03) and the other tested SNP were not linked with HCC risk. PNPLA3 and TM6SF2 variants were independently associated with HCC in patients with ALD (OR = 3.91 [CI95%:2.52-6.06], p = 1.14E-09; OR = 1.79 [CI95%:1.25-2.56], p = 0.001) but not with other etiologies. PNPLA3 SNP was also significantly associated with HCC developed on a nonfibrotic liver (OR = 2.19 [CI95%:1.22-3.92], p = 0.007). The association of PNPLA3 and TM6SF2 with HCC risk was confirmed in the prospective cohort with ALD. A genetic score including PNPLA3 and TM6SF2 minor alleles showed a progressive significant increased risk of HCC in ALD patients. In conclusion, PNPLA3-rs738409 and TM6SF2-rs58542926 are inherited risk variants of HCC development in patients with ALD in a dose dependent manner. The link between PNPLA3 and HCC on nonfibrotic liver suggests a direct role in liver carcinogenesis.

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