In the testicular cancer cell line, NT2, we previously demonstrated that differentially methylated regions were located in introns or intergenic regions, and postulated these might regulate non-coding RNAs. Three microRNAs and three small nucleolar RNAs were differentially methylated; one, miR-199a, was associated with the progression and prognosis of gastric and ovarian cancers. In this report we document, by epigenomic profiling of testicular tissue, that miR-199a is transcribed as antisense of dynamin 3 (chromosome 1q24.3), and hypermethylation of this region is correlated with miR-199a-5p/3p repression and tumor malignancy. Re-expression of miR-199a in testicular cancer cells led to suppression of cell growth, cancer migration, invasion and metastasis. The miR-199a-5p, one of two mature miRNA species derived from miR-199a, is associated with tumor malignancy. We further identified the embryonal carcinoma antigen podocalyxin-like protein 1 (PODXL), an anti-adhesive protein expressed in aggressive tumors, as a target of miR-199a-5p. We demonstrated PODXL is overexpressed in malignant testicular tumor, and cellular depletion of PODXL resulted in suppression of cancer invasion. The inverse relationship between PODXL and miR-199a-5p expression suggests PODXL is a downstream effector mediating the action of miR199a-5p. This report identifies DNA methylation, miR-199a dysregulation and PODXL as critical factors in tumor malignancy.
3 December 2009 in Birth Defects Research Part C: Embryo Today: Reviews
The granulosa cell (GC) is a critical somatic component of the ovary. It is essential for follicle development by supporting the developing oocyte, proliferating and producing sex steroids and disparate growth factors. Knowledge of the GC's function in normal ovarian development and function, and reproductive disorders, such as polycystic ovary syndrome (PCOS) and premature ovarian failure (POF), is largely acquired through clinical studies and preclinical animal models. Recently, microRNAs have been recognized to play important regulatory roles in GC pathophysiology. Here, we examine the recent findings on the role of miRNAs in the GC, including four related signaling pathways (Transforming growth factor-β pathway, Follicle-stimulating hormones pathway, hormone-related miRNAs, Apoptosis-related pathways) and relevant diseases. Therefore, miRNAs appear to be important regulators of GC function in both physiological and pathological conditions. We suggest that targeting specific microRNAs is a potential therapeutic option for treating ovary-related diseases, such as PCOS, POF, and GCT.
Refractory to apoptosis induced by anticancer drugs is one of the major causes of drug resistance in human cancers. The involvement of noncoding RNA (ncRNA) in cancer cell drug resistance has not yet been reported. By using the technique of RT-PCR-based differential display, a novel gene, cancer up-regulated drug resistant (CUDR) gene, was found to be overexpressed in a doxorubicin-resistant subline of human squamous carcinoma A431 and A10A cells, which were also more resistant to drug-induced apoptosis. The full-length CUDR mRNA transcript is ∼2.2 kb as detected by Northern blot analysis and has no sequence homology with other genes identified so far. Interestingly, no distinct open reading frame was found throughout the CUDR cDNA sequence, and no recombinant protein was detected from in vitro translation or from a protein lysate of human cancer cells after CUDR transfection. Therefore, CUDR is likely to exert its function as a noncoding RNA. Stable transfection with the CUDR gene was found to induce resistance to doxorubicin and etoposide as well as drug-induced apoptosis in A431 cells. By Western blot analysis, down-regulations of caspase 3 were observed in CUDR transfectants. On the other hand, overexpression of CUDR promoted anchorage-independent growth in A431 cells. Results from the present study suggest that CUDR may likely regulate the drug sensitivity and promote cellular transformation at least through caspase 3-dependent apoptosis.
Werner syndrome (WS) patients exhibit premature aging predominantly in mesenchyme-derived tissues, but not in neural lineages, a consequence of telomere dysfunction and accelerated senescence. The cause of this lineage-specific aging remains unknown. Here, we document that reprogramming of WS fibroblasts to pluripotency elongated telomere length and prevented telomere dysfunction. To obtain mechanistic insight into the origin of tissue-specific aging, we differentiated iPSCs to mesenchymal stem cells (MSCs) and neural stem/progenitor cells (NPCs). We observed recurrence of premature senescence associated with accelerated telomere attrition and defective synthesis of the lagging strand telomeres in MSCs, but not in NPCs. We postulate this "aging" discrepancy is regulated by telomerase. Expression of hTERT or p53 knockdown ameliorated the accelerated aging phenotypein MSC, whereas inhibition of telomerase sensitized NPCs to DNA damage. Our findings unveil a role for telomerase in the protection of accelerated aging in a specific lineage of stem cells.