Emerging role of microRNA in regulating long non coding RNA in breast cancer

Genome wide analysis reveals that only 2% of the genome is translated which gives the functional protein product. The remaining 98% do not code for any proteins and transcribed as non-coding RNAs (ncRNAs). These ncRNAs are involved in diverse biological processes. When these are deregulated, they cause cancer. microRNA (miRNA), a small ncRNA has been reported to be involved in cancer, but recently long non-coding RNAs (lncRNAs) are also emerged to be playing a role in cancers. LncRNAs are dysregulated in various types of cancer which includes breast, gastric, hepatocellular carcinoma etc. In this work, we considered an lncRNA, HULC (highly upregulated in liver cancer) to study its expression in breast cancer (which was not reported earlier) followed by studying its interaction with a miRNA, hsa-miR-30a-3p. From our qRT-PCR analysis, it is found that HULC is up- regulated and miRNA is down-regulated in breast cancer cell line, MDA-MB-231. Observing this inverse correlation in their expression followed by finding miRNA target sites within HULC, it was hypothesized that down-regulation of hsa-miR-30a-3p might be leading to the up-regulation of HULC in breast cancer. This reports a case where one small ncRNA regulate a lncRNA which might have implications in breast cancer.