T result in the overexpression of genes that contribute to the genomic instability of CCC. Although we did not find a statistical correlation between miR-21 overexpression and order AZD-8055 amplification of this region, overexpression of miR-21 was observed in 60 of the CCC cases examined. Targets of miR-21 in cancer include PTEN, PDCD4, LRRFIP1, RECK, TIMP-3, TPM1, BTG2, and Sprty2 [23]. PTEN can restrict growth and survival signals by limiting the activity of the phosphoinositide 3-kinase (PI3K) pathway. A decrease in PTEN might cause activation of the PI3K pathway, including Akt and mTOR, which leads to tumor development [24]. The prominent role of PTEN inactivation in CCC is thought to involve multiple mechanisms. In our study, loss of PTEN protein was observed in 46 of CCC patients. On the other hand, low of PTEN copy number was not indicted by CGH array (data not shown). Furthermore, no significant correlation was observed between miR-21 overexpression and loss of PTENexpression in our date set. Therefore, we suggest the involvement of another epigenetic mechanism, such as PTEN mutations, promoter methylation of PTEN, loss of heterozygosity at the PTEN locus other miR are infrequent in CCC. Although there was no statistical correlation between PTEN loss and miR-21 overexpression, the occurrence of 17q23-25 amplification along with both miR-21 overexpression and PTEN protein loss was detected in 14 of CCC cases. Thus, this oncogenetic mechanism might play a prominent role in CCC. Additionally, we showed PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/26795252 that miR-21 inhibition significantly increased PTEN expression in vitro. Moreover, the results obtained from the dual luciferase reporter assay supports the idea that miR-21 directly targets the PTEN gene, regulating the protein expression. It is therefore possible that miRNAs such as miR-21 modulate PTEN expression by transcriptional regulation or target degradation in CCC. Finally, we found a significant correlation between miR-21 overexpression and endometriosis in CCC. Endometriosisrelated CCC is thought to be a chronic inflammatory disease, characterized by increased production of proinflammatory cytokines such as IL-1, IL-6, IL-8, IL-10, and TNF- [25]. We recently reported that CCC showed a dominant Th-2 cytokine expression pattern driven largely by IL-6 expression [26]. In addition, IL-6 induces miR-21 expression through a STAT3-dependent pathway [27]. We also confirmed that IL-6 induces miR-21 overexpression in RMG-II (data not shown). In our study, miR-21 overexpression was observed in 60 of the CCC cases, regardless of 17q23-25 amplification status, suggesting another mechanism might regulate miR-21 expression. miR-21 might contribute to inflammation-inducedFigure 4 Chromosome 17q23-25 amplification, miR-21 expression, and PTEN protein expression in CCC. CGH array was performed to evaluate chromosomal alterations in 28 primary CCC tumors. Nine out of 28 patients (32 ) showed chromosomal amplification in the 17q23-25 region that contains miR-21. Seven of 9 tumors (77.7 ) with 17q23-25 amplification showed miR-21 overexpression. 17q23-25 amplification with both miR-21 overexpression and PTEN protein loss was detected in 4/28 cases (14.2 ).Hirata et al. BMC Cancer 2014, 14:799 http://www.biomedcentral.com/1471-2407/14/Page 9 ofcarcinogenesis in CCC with endometriosis. We need to further analyze miR21 expression using in situ hybridization in the endometriotic lesions of CCC specimens. The correlation between miR21 and endometriosis obs.
