Telomeres are specialized structures localized at the end of human chromosomes. Due to the end replication problem, each cell division results in a loss of telomeric repeats in normal somatic cells. In germ line and stem cells, the multicomponent enzyme telomerase maintains the length of telomere repeats. However, elevated telomerase activity has also been reported in the majority of solid tumours as well as in acute and chronic leukaemia. Chronic myeloid leukaemia (CML) serves as a model disease to study telomere biology in clonal myeloproliferative disorders. In CML, telomere shortening correlates with disease stage, duration of chronic phase (CP), prognosis measured by the Hasford risk score and the response to disease-modifying therapeutics such as the tyrosine kinase inhibitor Imatinib. In addition, telomerase activity (TA) is already increased in CP CML and further upregulated with disease progression to accelerated phase and blast crisis (BC). Furthermore, a correlation of TA with increased genetic instability as well as a shorter survival of the patients has been reported. Here, we review the current state of knowledge of the role of telomere and telomerase biology in CML and discuss the possible impact of novel treatment approaches.

Carcinogenesis is a multistep process involving alterations in various cellular pathways. The critical genetic events driving the evolution of primary liver cancer, specifically hepatoblastoma and hepatocellular carcinoma (HCC), are still poorly understood. However, telomere stabilization is acknowledged as prerequisite for cancer progression in humans. In this project, human fetal hepatocytes were utilized as a cell culture model for untransformed, proliferating human liver cells, with telomerase activation as first oncogenic hit. To elucidate critical downstream genetic events driving further transformation of immortalized liver cells, we used retroviral insertional mutagenesis as an unbiased approach to induce genetic alterations. Following isolation of hyperproliferating, provirus-bearing cell clones, we monitored cancer-associated growth properties and characterized changes toward a malignant phenotype. Three transformed clones with the ability to form colonies in soft agar were expanded. As proof-of-principle for our experimental setup, we identified a transforming insertion on chromosome 8 within the pleiomorphic adenoma gene 1 (PLAG1), resulting in a 20-fold increase in PLAG1 expression. Upregulation of PLAG1 has already been described to promote human hepatoblastoma development. In a separate clone, a transforming insertion was detected in close proximity to the receptor-interacting serine-threonine kinase 4 (RIPK4) with an approximately eightfold suppression in RIPK4 expression. As validation for this currently unknown driver in hepatocarcinogenesis, we examined RIPK4 expression in human HCC samples and confirmed a significant suppression of RIPK4 in 80% of the samples. Furthermore, overexpression of RIPK4 in transformed human fetal hepatocytes resulted in an almost complete elimination of anchorage-independent growth. On the basis of these data, we propose RIPK4 as a novel putative tumor suppressor in human hepatocarcinogenesis.

BackgroundHepatocellular carcinoma has a dismal prognosis due to recurrence rates of up to 70% after curative resection. Early recurrence is driven by synchronous microscopic intrahepatic metastases. The predictive value of histological parameters is discussed controversially and adjuvant therapy is not established. The aim of this study was to identify patients at high risk for early intrahepatic recurrence by expression profiling of selected micro RNAs.MethodsIn 52 patients undergoing HCC resection between 2011 and 2014, liver and tumor tissue was collected during surgery. Twelve patients with incomplete data regarding HCC recurrence, secondary liver transplantation, or perioperative death were excluded, leaving 40 patients with early recurrence <12 months (R+) or without recurrence for >24 months (R-) to compare grading, T, L, V, and R status. If tissue quality permitted, micro RNAs were measured in HCC and liver tissue.ResultsTen women and 30 men (64.0 ± 10.2 years) were analyzed. R+ occurred in 29 patients 6.2 ± 4.5 months after resection. Surveillance of R- was 26.2 ± 5.2 months. High intratumoral expression of miR-135a was associated with high risk of recurrence (HR = 4.2, p = 0.024, time to recurrence 8.8 ± 2.0 vs. 24.8 ± 4.4 months in patients with low miR-135a expression). As expected, T3 status was correlated with early recurrence, while other histological parameters and expression of miR-21, miR-122, and miR-125a did not.ConclusionsWe show a significant association between high expression of miR-135a and early HCC recurrence. Therefore, high intratumoral miR-135a expression might serve as a novel biomarker to identify patients urgently requiring adjuvant therapy post resection.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-017-3053-7) contains supplementary material, which is available to authorized users.