The N-terminally truncated isoform of Hv1 is overexpressed in tumorigenic human breast cell lines.

VENTURA, CLARA; LEON, IGNACIO ESTEBAN; ASUAJE, AGUSTÍN; ENRIQUE, NICOLÁS; MARTÍN, PEDRO; NÚÑEZ, MARIEL; COCCA, CLAUDIA; MILESI, VERÓNICA

Braga

Congreso; ISCaM2019 - 6th Annual meeting; 2019

International Society of cancer metabolism

The currentknowledge indicates that neoplastic transformation is associated with ametabolic deregulation and acid overproduction [1]. In breast cancer cells, we provedthat voltage-gated proton channel (Hv1) is functionally relevant in basalintracellular pH control. Comparing the effect of Hv1 inhibition in tumorigenic(MCF-7 and MDA-MB-231) and non-tumorigenic (MCF-10A) human breast cells wefound, that it induced cycle arrest and cell viabiliy reduction without affectingMCF-10A cells. Here, we explore if these differences could be associated withthe expression of the N-terminally truncated Hv1 isoform [HV1(S)] thatis specifically enriched in malignant B cells resulting in higherproliferation and migration [2]. Experimental: we examined (by western blot and flow cytometry) theexpression of the HV1 in the three human breast cell lines. We tested the amount of both isoform [Hv1(L+S)]using a polyclonal antibody which recognize the residues 32-44, present in bothisoforms. Then, the large isoform [Hv1(L)] was detected using anantibody that recognize the residues 1-30 of the N-terminal region present onlyin the Hv1(L).Results:  wefound an equal amount of Hv1(L+S) expressed amongthe three cell lines. However, the expression of Hv1(L) showed a signifcantdecrease (44% and 46% in MCF-7 and MDA-MB-231 respectively vs MCF-10A cellsp<0.01). Flow cytometry confirmed that Hv1(L) isoform is reduced (40%and 90 % in MCF-7 and MDA-MB-231 respectively vs the MCF-10A cells p<0.01). So,in both cases we can infer that such reduction represents the Hv1(S)amount.Conclusions: we demonstrated for the first time that breast cancer cellsoverexpress the HV1(S) isoform in comparison with non-tumorigenic breastcells. This result could explain the mayor sensibility to Hv1 inhibitionobserved in tumorigenic cells, as well as points out the importance ofevaluating the contribution of both isoforms to establish if the  HV1(S) could be a more selective markerof cellular malignancy References:[1]       KimJW, Dang CV (2006) Cancer?s molecular sweet tooth and the Warburg effect.Cancer Res 66:8927?8930. [2]       E. Hondares, et al., Proc. Natl. Acad. Sci. 111 (2014) 18078?18083.