The vacuolar ATPase subunit E controls apoptosis and is down-regulated in breast cancer

Mohammed, Saja; Mourtada-Maarabouni, Mirna

Abstract

Background
Vacuolar H+-ATPase (v-ATPase) is a large multisubunit proton pump that mediates the acidification of many intracellular compartments. Previous studies have strongly implicated v-ATPase in carcinogenesis and tumour progression and indicated that overexpression of its subunit ATP6V0a (a-subunit) promotes the survival and invasiveness of human breast cancer cells. A functional cloning approach to isolate genes involved in apoptosis resulted in the identification of ATP6V1E (v- ATPase subunit E) as a potential apoptosis regulatory gene. The aims of this study were to examine the effects of ATP6V1E overexpression on the cell death and survival of breast cancer cell lines.

Method
MCF7 and MDA-MB-231 cells were transfected either with plasmid encoding ATP6V1E transcript or empty vector. Culture growth, cell viability, apoptosis, and long term survival were assessed. The protein levels of v- ATPase subunit E and the autophagy marker LC3 conversion were analysed by western blotting. LysoSensor Green DND-189 was used to monitor changes in the cytosolic pH.

Results
Transfection of plasmid encoding ATP6V1E transcript in both cell lines caused a three-fold increase in the basal apoptotic rate, reduced culture viability and decreased the colony forming ability. Cells transfected with ATP6V1E showed an increase in LC3-II protein levels and acidification of cytosolic pH.

Conclusion
ATP6V1E regulates the survival of breast cancer cells. Overexpression of ATP6V1E promotes autophagy and apoptosis, decreased long term survival and altered the cytosol pH. While ATP6V0a appears to promote the survival of cancer cells, the present study suggests that ATP6V1E might function as tumour suppressor gene.

Citation

Mohammed, S., & Mourtada-Maarabouni, M. (2015, November). The vacuolar ATPase subunit E controls apoptosis and is down-regulated in breast cancer. Poster presented at 11th NCRI Cancer Conference, Liverpool

• Presentation Conference Type: Poster
• Conference Name: 11th NCRI Cancer Conference
• Conference Location: Liverpool
• Start Date: Nov 1, 2015
• End Date: Nov 4, 2015
• Acceptance Date: Sep 19, 2015
• Publication Date: Nov 3, 2015
• Series Title: 24th Biennial Congress of the European Association for Cancer Research (EACR24)
• Keywords: cancer
• Publisher URL: http://abstracts.ncri.org.uk/abstract/the-vacuolar-atpase-subunit-e-regulates-cell-death-in-human-breast-cancer-cells/