Changes in the expression profiles of claudins during gonocyte differentiation and in seminomas.

Testicular germ cell tumors (TGCTs) are the most common type of cancer in young men and their incidence has been steadily increasing for the past decades. TGCTs and their precursor carcinoma in situ (CIS) are thought to arise from the deficient differentiation of gonocytes, precursors of spermatogonial stem cells. However, the mechanisms relating failed gonocyte differentiation to CIS formation remain unknown. The goal of this study was to uncover genes regulated during gonocyte development that would show abnormal patterns of expression in testicular tumors, as prospective links between failed gonocyte development and TGCT. To identify common gene and protein signatures between gonocytes and seminomas, we first performed gene expression analyses of transitional rat gonocytes, spermatogonia, human normal testicular, and TGCT specimens. Gene expression arrays, pathway analysis, and quantitative real-time PCR analysis identified cell adhesion molecules as a functional gene category including genes downregulated during gonocyte differentiation and highly expressed in seminomas. In particular, the mRNA and protein expressions of claudins 6 and 7 were found to decrease during gonocyte transition to spermatogonia, and to be abnormally elevated in seminomas. The dynamic changes in these genes suggest that they may play important physiological roles during gonocyte development. Moreover, our findings support the idea that TGCTs arise from a disruption of gonocyte differentiation, and position claudins as interesting genes to further study in relation to testicular cancer.

miR-200bc/429 cluster targets PLCgamma1 and differentially regulates proliferation and EGF-driven invasion than miR-200a/141 in breast cancer.

The genes encoding microRNAs of the human miR-200 family map to fragile chromosomal regions and are frequently downregulated upon tumor progression. Although having been reported to regulate epithelial-to-mesenchymal transition and transforming growth factor-beta-driven cell invasion, the role of the miR-200 family in EGF-driven breast cancer cell invasion, viability, apoptosis and cell cycle progression is still unknown. In particular, there is no study comparing the roles of the two clusters of this miRNA family. In this study, we show for the first time that miR-200 family members differentially regulate EGF-driven invasion, viability, apoptosis and cell cycle progression of breast cancer cells. We showed that, all miR-200 family members regulate EGF-driven invasion, with the miR-200bc/429 cluster showing stronger effects than the miR-200a/141 cluster. Furthermore, expression of the miR-200a/141 cluster results in G1 arrest supported by increased p27/Kip1 and decreased cyclin dependent kinase 6 expression. In contrast, expression of the 200bc/429 cluster decreases G1 population and increases G2/M phase, in line with the observed reduction of p27/Kip1 and upregulation of the inhibitory phosphorylation of Cdc25C, respectively. To test the hypothesis that phenotypical differences observed between the two clusters are caused by differential targeting spectrums, we performed genome-wide microarray profiling in combination with gain-of-function studies. This identified phospholipase C gamma 1 (PLCG1), which was downregulated only by the miR-200bc/429 cluster, as a potential candidate contributing to these phenotypical differences. Luciferase reporter assays validated PLCG1 as a direct functional target of miR-200bc/429 cluster, but not of miR-200a/141 cluster. Finally, loss of PLCG1 in part mimicked the effect of miR-200bc/429 overexpression in viability, apoptosis and EGF-driven cell invasion of breast cancer cells. Our results suggest that the miR-200 family has a tumor-suppressor function by negatively regulating EGF-driven cell invasion, viability and cell cycle progression in breast cancer.

Mutation of COL11A2 causes autosomal recessive non-syndromic hearing loss at the DFNB53 locus.

BACKGROUND: Allele variants of COL11A2, encoding collagen type XI alpha2, cause autosomal dominant non-syndromic hearing loss (ARNSHL) at the DFNA13 locus (MIM 601868) and various syndromes that include a deafness phenotype. OBJECTIVE: To describe a genome-wide scan carried out on a consanguineous Iranian family segregating ARNSHL. RESULTS: Genotyping data identified a novel locus for ARNSHL on chromosome 6p21.3, which was designated DFNB53. Homozygosity for the P621T mutation of COL11A2 was present in all deaf persons in this family; this same variation was absent in 269 Iranian controls. Sequence comparison of collagen type XI alpha1 and alpha2 peptides across species shows that the replaced proline is an evolutionarily conserved amino acid. CONCLUSIONS: The P621T mutation of COL11A2 affects the Y position of the canonical -Gly-X-Y- repeat in collagens. It lies near the amino-terminus of the triple helical region and causes ARNSHL. This finding suggests that mutation type and location are critical determinants in defining the phenotype of COL11A2 associated diseases.