Primate-Specific Estrogen-Induced Long Noncoding Rnas As Targets For Breast Cancer Treatment

Abstract Purpose: Estrogen is a proliferative hormone that regulates the growth of estrogen receptor positive cells, including breast cancer cells. Although estrogen is a global regulator of protein-coding genes as well as non-coding RNA (ncRNA) genes, its effects on long ncRNA (lncRNA) genes, the most abundant class of human ncRNAs, remain poorly understood. We previously used custom microarrays and Taqman qRTPCR to identify 127 estrogen-responsive lncRNAs, and demonstrated a direct role for 25 of these in breast cancer cell viability and proliferation: estrogen-induced lncRNAs cause cell proliferation (reversed upon siRNA knockdown of these lncRNAs) and estrogen-repressed lncRNAs cause cell death (induced upon overexpression of those lncRNAs). Furthermore, since over 60% of human lncRNAs, including CR593775, are primate-specific, eight additional primate-specific lncRNAs were used in functional assays to determine whether primate-specific lncRNAs are functional in breast cancer. Methods/Results: We ablated two new estrogen-induced primate-specific lncRNAs with two independent siRNAs each and validated the knockdowns by qRTPCR. Post-transfection MTT and crystal violet cell proliferation assays revealed that for one lncRNA, both knockdowns reduced cell viability and proliferation. We also used Stellaris RNA fluorescent in situ hybridization (FISH) to determine that the primate-specific estrogen-repressed cell death inducer lncRNA BC041455 is cytoplasmic in MCF7 cells. In addition, CR593775, our top estrogen-induced lncRNA, does not regulate the viability and proliferation of nonmalignant MCF10A breast cells as compared to breast cancer cells that are estrogen receptor positive (T47D, MCF7) and negative (MDA-MB-231). Conclusion: The primate-specific estrogen-induced lncRNAs are cytoplasmic targets for breast cancer treatment that leads to reduced proliferation and cell viability. Citation Format: Donghong Ju, Daniel Xie, Juan Cai, Anton Scott Goustin, Mary A. Kosir, Leonard Lipovich. Primate-specific estrogen-induced long noncoding RNAs as targets for breast cancer treatment. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1262.