Rajkumar, Thangarajan

Background:: Breast cancer is one of the leading causes of cancer deaths in women. Early diagnosis offers the best hope for a cure. Ductal carcinoma in situ is considered a precursor of invasive ductal carcinoma of the breast. In this study, we carried out microRNA sequencing from 7 ductal carcinoma in situ (DCIS), 6 infiltrating ductal carcinomas (IDC Stage IIA) with paired normal, and 5 unpaired normal breast tissue samples. We identified 76 miRNAs that were differentially expressed in DCIS and IDC. Methods:: Additionally, we provide preliminary evidence of miR-365b-3p and miR-7-1-3p being overexpressed, and miR-6507-5p, miR-487b-3p, and miR-654-3p being downregulated in DCIS relative to normal breast tissue. We also identified a miRNA miR-766-3p that was overexpressed in early-stage IDCs. The overexpression of miR-301a-3p in DCIS and IDC was confirmed in 32 independent breast cancer tissue samples. Results:: Higher expression of miR-301a-3p is associated with poor overall survival in The Can-cer Genome Atlas Breast Cancer (TCGA-BRCA) dataset, indicating that it may be associated with DCIS at high risk of progressing to IDC and warrants deeper investigation. Conclusion:: We also analyzed competing endogenous networks associated with differentially expressed miRNAs and identified LRRC75A-AS1 and MAGI2-AS3 as lncRNAs that potentially play an important role in early-stage breast cancers.

Breast cancer is the most common malignancy among women, with the highest incidence rate worldwide. Dysregulation of long noncoding RNA s during the preliminary stages of breast carcinogenesis is poorly understood. In this study, we performed RNA sequencing to identify long noncoding RNA expression profiles associated with early‐stage breast cancer. RNA sequencing was performed on six invasive ductal carcinoma (IDC) tissues along with paired normal tissue samples, seven ductal carcinoma in situ tissues, and five apparently normal breast tissues. We identified 375 differentially expressed lncRNAs (DElncRNAs) in IDC tissues compared to paired normal tissues. Antisense transcripts (~ 58%) were the largest subtype among DE lnc RNA s. About 20% of the 375 DE lnc RNA s were supported by typical split readings leveraging their detection confidence. Validation was performed in n = 52 IDC and paired normal tissue by qRT ‐ PCR for the identified targets ( ADAMTS 9‐ AS 2, EPB 41L4A‐ AS 1, WDFY 3‐ AS 2, RP 11‐295M3.4, RP 11‐161M6.2, RP 11‐490M8.1, CTB ‐92J24.3, and FAM 83H‐ AS 1). We evaluated the prognostic significance of DE lnc RNA s based on TCGA datasets and report that overexpression of FAM 83H‐ AS 1 was associated with patient poor survival. We confirmed that the downregulation of ADAMTS 9‐ AS 2 in breast cancer was due to promoter hypermethylation through in vitro silencing experiments and pyrosequencing.