Impaired expression of Drosha in breast cancer.

BACKGROUND: Impaired miRNAs processing pathway is one interesting scenario for global downregulation of the miRNAome in various types of malignancy. We previously reported that DGCR8 and Dicer genes dysregulated in patients with breast cancer. OBJECTIVE: To evaluate the expression pattern of Drosha in patients with breast cancer. METHODS: We evaluated the mRNA expression level of Drosha in 70 fresh breast carcinomas and adjacent non-neoplastic tissue using quantitative real-time PCR and assessed the possible correlation between its expression and clinicopathological parameters. RESULTS: Our results revealed that mRNA expression level of Drosha was decreased in tumors when compared to adjacent non-neoplastic tissue. However, this difference is not statistically significant (P > 0.05). Downregulation of Drosha is related to older age at diagnosis, higher histological grade, higher tumor size and metastasis. However, there was no significant correlation between Drosha expression level and clinicopathological parameters (P > 0.05). We found that Drosha expression negatively correlated with DGCR8 (P = 0.043), whereas dysregulated expression levels of Drosha and Dicer are positively correlated with to each other (P < 0.0001). CONCLUSION: This study provides evidence that the expression of Drosha is impaired in breast cancer. However, the molecular basis of observed expression pattern have remained inexplicable and should be further investigated.

Upregulation of the double-stranded RNA binding protein DGCR8 in invasive ductal breast carcinoma.

High-throughput experimental studies have indicated that the miRNAome is globally downregulated in various types of malignancy, and dysregulation of miRNAs processing component(s) is one possible mechanism for this phenomenon. Despite the progression in identifying cellular functions of Digeorge Syndrome Critical Region 8 (DGCR8) in miRNAs biogenesis, the role of altered expression of DGCR8 in the pathogenesis of invasive ductal breast carcinoma (IDC) has not yet been fully investigated. The objective of the present study was to evaluate DGCR8 mRNA expression in seventy fresh invasive ductal breast carcinomas and matched adjacent non-neoplastic tissues using quantitative real-time PCR and to assess the value of clinicopathological parameters on its expression. Our findings revealed that DGCR8 mRNA expression is upregulated in more than two-thirds of the cancerous specimens (68.66%) when compared to adjacent non-neoplastic tissue. This difference is statistically significant (P<0.05). We found that DGCR8 mRNA levels were increased in the high-grade and metastatic compared with those of both low-grade and non-metastatic. We demonstrated that there is not significant correlation between DGCR8 mRNA expression levels and clinicopathological parameters. In conclusion, our study suggested that upregulation of DGCR8 may be involved in tumorigenesis and aggressiveness of IDC and may serve as future therapeutic target.

Dysregulated expression of Dicer in invasive ductal breast carcinoma.

Several lines of evidence suggest that the global down-regulation of the microRNAome (miRNAome) involved in pathogenesis of various malignancies. Impaired microRNAs processing pathway is one possible mechanism for global down-regulation of the miRNAome. Dicer is a key enzyme in miRNA processing pathway, and dysregulation of its expression has been suggested as a possible cause of miRNAome alterations observed in various cancers. However, Dicer mRNA expression in invasive ductal breast carcinoma (IDC) has not been investigated in depth. Therefore, this study aimed to evaluate the mRNA expression of Dicer in IDC and also to assess the correlation of its expression with clinicopathological parameters including age, histological grade, tumor size and lymph node metastasis. We investigated the expression of the Dicer in seventy fresh invasive ductal breast carcinomas and matched adjacent non-neoplastic tissue by quantitative real-time PCR using validated reference genes. In addition, the possible impact of clinicopathological characteristics on Dicer expression levels was analyzed. Our results showed that Dicer mRNA expression is down-regulated in slightly more than half (51.43 %) of the tumor specimens when compared to adjacent non-neoplastic tissue. Comparison of the Dicer expression level between tumor and matched adjacent non-neoplastic tissue showed that there is no statistical significant differences between them (P = 0.425). We also found that Dicer mRNA expression in IDC samples was not correlated with clinicopathological features. In conclusion, our findings provide additional evidence to support the hypothesis that Dicer expression down-regulated in breast cancer. This study suggested that the decreased expression of Dicer may be potential underlying mechanism in pathogenesis of IDC.