Potent Proapoptotic Molecule miR133a and b perform similar if not identical cellular functions by regulating the expression of a common pool of target genes. In addition, miR-133a and the co-transcribed miR-1 were recently described to exhibit a reduced expression in prostate and bladder cancer in which miR-133a targets Transgelin 2, a gene with oncogenic properties that was strongly downregulated in our pSILAC dataset. So far, miR-133b has been almost exclusively described in the context of miR signatures from tumor samples or cancer cell lines and its potential for diagnostics and prognosis. Previous reports demonstrate a significant downregulation of miR-133b in transformed tissue compared to healthy controls. One recent report ascribes tumor-promoting 19151731” functions to miR-133b in in-vitro and in-vivo models of cervical cancers. This work focused on cervical cell lines other than HeLa cells, which were inspected for their expression levels of miR-133b. In this cell line miR-133b levels werefound to be slightly elevated compared to other cervical cancer cell lines. Our HeLa experiments point to a proapoptotic and presumably antitumorigenic role of miR-133b. Therefore it is conceivable that miR-133b fulfills different roles in HeLa cells and other cervical cancer cell lines. It is well known that the same molecule can have opposing roles in different cellular settings. Note, that differential results were obtained while examining the expression of miR-133b in cervical cancer compared to healthy tissue. One study reports upregulation of this miR as revealed by qRT-PCR whereas a sequencing approach and microarray analysis point to a repression of miR-133b in tumor tissue. Further experiments will be necessary to clarify this conundrum of pro- or antiapoptotic functions of miR-133b in cervical and other types of cancer. Herein, we addressed the question whether miR-133b is also downregulated in prostate cancer. We show that miR-133b expression is reduced in the majority of prostate cancers when compared to normal adjacent tissue. Remarkably, MedChemExpress K-858 patients with a low abundance of miR-133b tend to experience biochemical relapse more frequently. Accordingly, transfection of a prostate tumor cell line with synthetic miR-133b mimics resulted in sequence-specific impairment of proliferation capacity, suggesting a functional relevance of the reduced miR-133b expression in cancerous prostate cells. Ongoing work focuses on elucidating the exact molecular mechanisms responsible for this phenotype. Finally, our results 10460232” identify miR-133b as a highly versatile and potent proapoptotic molecule with tumor suppressor properties. The evidence provided here, in combination with previous findings showing that miR-133b is concordantly repressed in various tumor types and, that it is capable of regulating the intrinsic apoptotic pathway and expression of important onco- N 7 miR-133b, a Potent Proapoptotic Molecule Germany). All cell lines were kept in culture under conditions recommended by the American Type Culture 
Collection . Patients and tissue samples Tumor tissue and normal adjacent tissue from 69 patients with prostate carcinoma were collected after radical prostatectomy at Charite University Hospital between 2001 and 2005. Samples were snap-frozen directly after surgery. Tumor areas were identified by haematoxylin and eosin staining and tumor and normal adjacent tissue was punch-biopsied with a 1-mm tissue microarray needle. Tumor content of the punches was h
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