title: KR-33028, a potent inhibitor of the Na+/H+exchanger NHE1, suppresses metastatic potential of triple-negative breast cancer cells.
abstract: Hyper-activation of the Na+/H+exchanger NHE1 occurs at the onset of oncogenic transformation and plays a critical role in breast cancer carcinogenesis. Dysregulation of NHE1 activity results in intracellular alkalinization and the acidification of the extracellular tumor microenvironment that promotes metastasis. Hence, the use of chemical inhibitors of NHE1 as chemotherapeutic agents is an alluring prospect. We previously demonstrated that two structurally different NHE1 inhibitors, EMD87580 [(2-methyl-4,5-di-(methylsulfonyl)-benzoyl)-guanidine], and HMA [5-(N,N-hexamethylene)-amiloride], were effective as co-adjuvants to potentiate paclitaxel-mediated cytotoxic chemotherapy in triple-negative breast cancer (TNBC) cells. Both these drugs, however, had reduced or minimal anti-cancer effects when used alone. Here, we tested KR-33028 (4-cyano (benzo[b]thiophene-2-carbonyl)guanidine), a potent and selective inhibitor of NHE1, to determine its efficacy in inhibition of metastatic potential of TNBC cells. In highly invasive MDA-MB-231, moderately invasive MDA-MB-468, and lowly invasive Hs578T TNBC cells, KR-33028 considerably reduced rates of cell migration and anchorage-independent colony growth. Invasion of MDA-MB-231 and MDA-MB-468 cells through extracellular matrix was also dramatically decreased in response to KR-33028. We further tested the effect of KR-33028 on MDA-MB-231 cells lacking NHE1 expression (231koNHE1); no differences were observed between untreated control and KR-33028-treated 231koNHE1 cells. Taken together, our results highlight the in vitro efficacy of KR-33028-mediated NHE1 inhibition on limiting cellular functions that are predictive of metastasis in vivo. We suggest that targeting NHE1 in the development of novel chemotherapeutics could be highly effective in combatting triple-negative breast cancer and that KR-33028 is potentially useful in prevention of metastasis.
authors: Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada. Electronic address: amith@ualberta.ca.
authors: Schammim Ray
authors: SR
authors: Amith
authors: Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada. Electronic address: jmwilkin@ualberta.ca.
authors: Jodi Marie
authors: JM
authors: Wilkinson
authors: Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada. Electronic address: lfliegel@ualberta.ca.
authors: Larry
authors: L
authors: Fliegel
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology / Q000556:secondary; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002277:Carcinoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D027682:Cation Transport Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D055786:Gene Knockout Techniques; D006146:Guanidines / Q000494:pharmacology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D020128:Inhibitory Concentration 50; D007424:Intracellular Fluid / Q000737:chemistry / Q000187:drug effects; D049990:Membrane Transport Modulators / Q000494:pharmacology*; D009361:Neoplasm Invasiveness; D009363:Neoplasm Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D013876:Thiophenes / Q000494:pharmacology*; D064726:Triple Negative Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D059016:Tumor Microenvironment / Q000187:drug effects; D014410:Tumor Stem Cell Assay
chemical_list: D000970:Antineoplastic Agents; D027682:Cation Transport Proteins; D006146:Guanidines; D049990:Membrane Transport Modulators; C507425:N-(4-cyano-benzo(b)thiophene-2-carbonyl)guanidine; D009363:Neoplasm Proteins; C490998:SLC9A1 protein, human; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers; D013876:Thiophenes
keywords: KR-33028; Metastasis; NHE1; Triple-negative breast cancer