The reverse pH gradient is a major feature associated with
cancer cell reprogrammed metabolism. This phenotype is supported by increased activity of pH regulators like
ATPases,
carbonic anhydrases (CAs), monocarboxylate transporters (MCTs) and
sodium-
proton exchangers (NHEs) that induce an acidic tumor microenvironment, responsible for the
cancer acid-resistant phenotype. In this work, we analyzed the expression of these pH regulators and explored their inhibition in
breast cancer cells as a strategy to enhance the sensitivity to
chemotherapy. Expression of the different pH regulators was evaluated by immunofluorescence and Western blot in two
breast cancer cell lines (MDA-MB-231 and MCF-7) and by immunohistochemistry in human
breast cancer tissues. Cell viability, migration and invasion were evaluated upon exposure to the pH regulator inhibitors (PRIs)
concanamycin-A,
cariporide,
acetazolamide and cyano-4-hydroxycinnamate. Additionally, PRIs were combined with
doxorubicin to analyze the effect of cell pH dynamic disruption on
doxorubicin sensitivity. Both
cancer cell lines expressed all pH regulators, except for MCT1 and CAXII, only expressed in MCF-7 cells. There was higher plasma membrane expression of the pH regulators in human
breast cancer tissues than in normal breast epithelium. Additionally, pH regulator expression was significantly associated with different molecular subtypes of
breast cancer. pH regulator inhibition decreased
cancer cell aggressiveness, with a higher effect in MDA-MB-231. A synergistic inhibitory effect was observed when PRIs were combined with
doxorubicin in the
breast cancer cell line viability. Our results support
proton dynamic disruption as a
breast cancer antitumor strategy and the use of PRIs to boost the activity of conventional
therapy.