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Leukocyte telomere length (TL) has been suggested as a marker of biological age in healthy
individuals, but can also reflect inherited and acquired hematopoietic dysfunctions or indicate an
increased turnover of the hematopoietic stem and progenitor cell compartment. In addition, TL is able
to predict the response rate of tyrosine kinase inhibitor therapy in chronic myeloid leukemia (CML),
indicates clinical outcomes in chronic lymphocytic leukemia (CLL), and can be used as screening tool
for genetic sequencing of selected genes in patients with inherited bone marrow failure syndromes
(BMFS). In tumor cells and clonal hematopoietic disorders, telomeres are continuously stabilized by
reactivation of telomerase, which can selectively be targeted by telomerase-specific therapy. The use of
the telomerase inhibitor Imetelstat in patients with essential thrombocythmia or myelofibrosis as well
as the use of dendritic cell-based telomerase vaccination in AML patients with complete remissions are
promising examples for anti-telomerase targeted strategies in hematologic malignancies. In contrast,
the elevation in telomerase levels through treatment with androgens has become an exciting clinical
intervention for patients with BMFS. Here, we review recent developments, which highlight the
impact of telomeres and telomerase targeted therapies in hematologic dysfunctions.
Introduction: Inhibition of androgen synthesis by abiraterone acetate (AA) entails enhanced overall survival rates and clinical benefit for patients with locally advanced and metastasized prostate cancer (PC). The expression of heat shock protein 27 (HSP27) is generally associated with cytoprotection and was demonstrated to mediate chemoresistance under cytostatic therapy, for instance, docetaxel treatment. In this study, we investigated the impact of AA treatment on HSP27 expression and PC cell growth. Materials and Methods: HSP27 expression levels in docetaxel and AA-treated PC cell lines LNCaP and PC-3 were determined by SDS PAGE and Western blot analysis. Proliferation assays were performed using a CASY Cell Counter and Analyzer Model TT (Roche Applied Science). Results: Despite significantly increased HSP27 expression in PC cells incubated with docetaxel, Western blot analysis implicated a significant reduction of the cytoprotective HSP27 in AA-treated PC cells. Notably, HSP27 stably overexpressed in PC-3-HSP27 cells did not appear as an HSP27-mediated proliferation benefit in the presence of AA as shown in docetaxel incubation studies. Conclusion: In contrast to repeatedly demonstrated HSP27-driven chemoresistance related to chemotherapeutics, our results may constitute a broader molecular mode of action of AA chemotherapy. AA efficacy may exert an HSP27 suppressive role that goes beyond the primarily assumed inhibition of androgen biosynthesis.