BHLHE40-AS1 a Long-noncoding RNA Regulates DEC1 on Breast Cancer Progression
Ductal Carcinoma in Situ (DCIS) is a precursor to breast cancer where abnormal cells have been found in the mammary duct but have not become invasive and spread into surrounding tissue. There has been an increase in early diagnosis of DCIS, but only around 40% of the cases ever progress to an invasive stage, and thus detection can lead to unnecessary surgeries. To identify which of these 40% progress, long noncoding RNAs were used. Through RNA sequencing of DCIS and invasive cells from real patient samples, BHLHE40-AS1 was discovered, a long-noncoding RNA, to be highly expressed in invasive breast cancer and low in DCIS, suggesting that BHLHE40-AS1 supports breast cancer progression. We hypothesize that BHLHE40-AS1 affects cellular protein expression and down regulates DEC1 protein expression in the cell. Reasons for protein loss could be through transcription, translation, and protein degradation; we are focusing on inhibiting transcription. To determine if BHLHE40-AS1 is altering DEC1 mRNA abundance, we treated our cells with small interfering RNA (siRNA). A qPCR was conducted to observe the knockdown of the expression of BHLHE40-AS1 and of DEC1. The siRNA was targeted against BHLHE40-AS1, and when we observed knockdown of BHLHE40-AS1 we also got knockdown of DEC1 mRNA. To determine the half-life of DEC1 we used Actinomycin D, which is known to inhibit transcription and measure mRNA abundance over time. When measuring the stability of DEC1 RNA with siRNA’s, the change in rate between the siRNA’s and the control is small leading to the conclusion that the effect on DEC1 is not due to transcript degradation, but may be due to a problem with transcription. To validate this hypothesis, we will next perform a nuclear run-on assay. In conclusion, we have identified a long noncoding RNA that may support breast cancer progression, through interaction with DEC1. After validating our observations, we will test BHLHE40-AS1 affect on progression an in vivo mouse model.