Cause-specific telomere factors deregulation in hepatocellular carcinoma.

International audienceBACKGROUND: Among the numerous genetic defects associated with hepatocarcinogenesis, telomere abnormalities appear to play a role both in tumor promotion and maintenance. Telomeres, the chromosome extremities, are protected by specific proteins, the shelterin complex and by additional factors. Besides telomerase dysregulation, expression changes of these telomere factors have been observed in cancers. METHODS: Here, we tested the hypothesis that such dysregulation might occur in hepatocellular carcinoma (HCC) with specific patterns depending on the cause of HCC. We compared telomere length, telomerase activity (TA), hTERT and telomere genes expression using PCR and Western-blot analyses between non-cirrhotic liver, peritumoral cirrhotic tissue (40 samples) and cancerous tissue (40 samples) derived from 40 patients with HBV-, HCV-, or alcohol-related HCC. RESULTS: Alterations in TA, hTERT expression and telomere length between non-cirrhotic, cirrhotic, and tumor samples were not significantly influenced by the cause of HCC. In contrast, the expression pattern of hTR, shelterin, and non-shelterin telomere protective factors clearly distinguished the 3 causes of cirrhosis and HCC. For patients with HBV diseased liver, when compared with non-cirrhotic liver, the cirrhotic tissue underexpressed all shelterin and all but HMRE11A and RAD50 non-shelterin telomere factors. For HCV the expression level of POT1, RAP1, Ku80, and RAD50 was higher in cirrhotic than in non-cirrhotic liver samples without evidence for significant transcriptional change for the remaining genes. For alcohol-related liver diseases, the expression level of POT1, RAP1, TIN2, hMRE11A, hMRE11B, Ku70, Ku80, RAD50, TANK1, and PINX1 was higher in cirrhotic than in non-cirrhotic liver samples. For the 3 causes of HCC, there was no significant change in shelterin and non-shelterin gene expression between cirrhosis and HCC samples. CONCLUSIONS: These results validate our hypotheses and demonstrate that cirrhosis and HCC add-up numerous telomere dysfunctions including numerous cause-specific changes that appear to occur early during the course of the disease

Cloned HTLV-1+CD4+, but not CD8+, T-cells display an oncogenic miRNome

HTLV-1 persistence in vivo relies on the persistent clonal expansion of its host cells. These are CD4+ and CD8+ T cells, yet ATL is regularly CD4+. Accordingly, untransformed HTLV-1+CD4+ but not CD8+ T cells cloned from carriers cumulate the features of preleukemic cells, including multinuclearity, chromatin bridges, increased cell cycling and inappropriate telomerase activity. MicroRNAs (miR) modify the maturation of a plethora of T-cells RNA and their deregulation would therefore constitute an appropriate explanation for the Tax-dependent or -independent pleiotropic changes in the phenotype of HTLV-1+CD4+ T cells. As the miRNome of naturally infected untransformed cells has not been investigated to date, we assessed the miR expression profiling of T cells cloned from carriers. Microarray results, confirmed by quantitative RTPCR, showed that, upon infection, CD4+ and CD8+ clones yielded aberrant expression of 15 distinct miRs including miR-34b and miR-494 that were respectively over- and underexpressed in both compartments. The more prominent effect of the infection consisted in the CD4+-restricted overexpression of the cancer-related miRs miR-21, -27b and -23b associated with the CD4+-restricted downregulation of the proapoptotic miR-15 and -16. Data were extended by the analysis of 40 additional CD4+ clones (20 infected). Crossing the miRNome against the whole transcriptome data identified putative miR-targeted genes. In silico, those targeted by miR-23b and -27b defined 2 hitherto unknown pathways involving the cell cycle and genetic disorders. Therefore HTLV-1 triggers a phenotype-specific miR signature consistent with the preleukemic HTLV-1+CD4+ phenoty

A dose-effect relationship for deltaretrovirus-dependent leukemogenesis in sheep

<p>Abstract</p> <p>Background</p> <p>Retrovirus-induced tumors develop in a broad range of frequencies and after extremely variable periods of time, from only a few days to several decades, depending mainly on virus type. For hitherto unexplained reasons, deltaretroviruses cause hematological malignancies only in a minority of naturally infected organisms and after a very prolonged period of clinical latency.</p> <p>Results</p> <p>Here we demonstrate that the development of malignancies in sheep experimentally infected with the deltaretrovirus bovine leukemia virus (BLV) depends only on the level of BLV replication. Animals were experimentally infected with leukemogenic or attenuated, but infectious, BLV molecular clones and monitored prospectively through 8 months for viral replication. As early as 2 weeks after infection and subsequently at any time during follow-up, leukemogenic viruses produced significantly higher absolute levels of reverse transcription (RT), clonal expansion of infected cells, and circulating proviruses with RT- and somatic-dependent mutations than attenuated viruses. These differences were only quantitative, and both kinds of viruses triggered parallel temporal fluctuations of host lymphoid cells, viral loads, infected cell clonality and proliferation.</p> <p>Conclusion</p> <p>Deltaretrovirus-associated leukemogenesis in sheep appears to be a two-hit process over time depending on the amounts of first horizontally and then vertically expanded viruses.</p

Early and transient reverse transcription during primary deltaretroviral infection of sheep

<p>Abstract</p> <p>Background</p> <p>Intraindividual genetic variability plays a central role in deltaretrovirus replication and associated leukemogenesis in animals as in humans. To date, the replication of these viruses has only been investigated during the chronic phase of the infection when they mainly spread through the clonal expansion of their host cells, vary through a somatic mutation process without evidence for reverse transcriptase (RT)-associated substitution. Primary infection of a new organism necessary involves allogenic cell infection and thus reverse transcription.</p> <p>Results</p> <p>Here we demonstrate that the primary experimental bovine leukemia virus (BLV) infection of sheep displays an early and intense burst of horizontal replicative dissemination of the virus generating frequent RT-associated substitutions that account for 69% of the in vivo BLV genetic variability during the first 8 months of the infection. During this period, evidence has been found of a cell-to-cell passage of a mutated sequence and of a sequence having undergone both RT-associated and somatic mutations. The detection of RT-dependent proviral substitution was restricted to a narrow window encompassing the first 250 days following seroconversion.</p> <p>Conclusion</p> <p>In contrast to lentiviruses, deltaretroviruses display two time-dependent mechanisms of genetic variation that parallel their two-step nature of replication <it>in vivo</it>. We propose that the early and transient RT-based horizontal replication helps the virus escape the first wave of host immune response whereas somatic-dependent genetic variability during persistent clonal expansion helps infected clones escape the persistent and intense immune pressure that characterizes the chronic phase of deltaretrovirus infection.</p

Long-term follow-up of autologous stem cell transplantation after intensive chemotherapy in patients with myelodysplastic syndrome or secondary acute myeloid leukemia.

International audienceWe report on the outcomes of 53 patients with myelodysplastic syndromes (MDS) or acute myeloid leukemia secondary to MDS, autografted in first complete remission. Five (9.4%) died from the procedure whereas hematological reconstitution occurred in all the remaining patients. Forty patients (75%) relapsed, with 87.5% of the relapses occurring within 2 years of the autologous transplant. With a median follow-up of 6.2 years, the median actuarial disease-free survival and overall survival were 8 and 17 months after autograft, respectively. Karyotype was the only prognostic factor for disease-free and overall survival. The eight survivors (15%), including two patients with unfavorable or intermediate karyotype, remained in first complete remission 50+ to 119+ months after transplantation and are probably cured

HTLV-1 met en cycle les lymphocytes T CD4+ non transformés, protége les lymphocytes T CD8+ de l'apoptose, et établit un phénotype préleucémique restreint aux lymphocytes T CD4+Titre

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF