Amiloride and guggulsterone suppression of esophageal cancer cell growth in vitro and in nude mouse xenografts

Abstract

Esophageal adenocarcinoma is increasing in the US and Western countries and frequent gastresophageal reflux or gastresophageal reflux disease carrying gastric acid and bile acid could contribute to esophageal adenocarcinogenesis. This study was designed to detect the expression of gastric acid-inducing gene Na + /H + exchanger-1 (NHE-1) ex vivo and then to explore targeting of NHE-1 expression or activity to control esophageal cancer cell viability in vitro and in nude mouse xenografts. The data showed that NHE-1 was highly expressed in esophageal adenocarcinoma tissues (66 of 101 cases [65.3%], but not in normal esophageal squamous cell epithelium (1 of 26 cases [3.8%]). Knockdown of NHE-1 expression using NHE-1 shRNA or inhibition of NHE-1 activity using the NHE-1 inhibitor amiloride suppressed viability and induced apoptosis in esophageal cancer cells. Molecularly, amiloride inhibited expression of cyclooxygenase-2 and matrix metallopeptidase-9 but not NHE-1 mRNA in esophageal cancer cells. A combination of amiloride and guggulsterone (a natural bile acid receptor inhibitor) showed more than additive effects in suppressing esophageal cancer cell growth in vitro and in nude mouse xenografts. This study suggests that inhibition of NHE-1 expression or activity or combination of amiloride and guggulsterone could be useful in control of esophageal adenocarcinoma.

(Patho-)Physiology of Na+/H+ Exchangers (NHEs) in the Digestive System

“…Inhibiting the expression of NHE1 with shRNA or its activity with amiloride resulted in an intracellular acidification of esophageal cancer cells which decreased their viability and even induced apoptosis. The suppression of tumor xenograft formation in nude mice could also be observed (Guan et al, 2014). Interestingly, Goldman and colleagues reported that stimulation of JH-EsoAd1 EAC cells or cells of the Barrett's esophagus cell line CP-A with hydrophobic bile acid will activate NHE.…”

“…While sharing a poor 5-year overall survival rate of about 15%, EAC and ESCC originate from different cells and also differ regarding their incidence and epidemiology (Talukdar et al, 2018). EAC is an Shallat et al, 1995;Park et al, 2015Shallat et al, 1995Khan, 2003 Fitzgerald et al, 1998;Ostrowski et al, 2007;Goldman et al, 2010;Laczko et al, 2016Goldman et al, 2011Guan et al, 2014Ariyoshi et al, 2017 NHE1 Stomach…”

“…• Clostridium difficile induced antibiotic-associated diarrhea Hayashi et al, 2004;Engevik et al, 2015 (Continued) Sullivan et al, 2009;Yeruva et al, 2010;Farkas et al, 2011;Lenzen et al, 2012 aggressive malignancy whose occurrence can be significantly abetted by gastric or even bile acid reflux due to GERD (Stephens et al, 2018). Guan et al (2014) found that NHE1 was highly expressed in EAC tissue but not in normal esophageal epithelium. Inhibiting the expression of NHE1 with shRNA or its activity with amiloride resulted in an intracellular acidification of esophageal cancer cells which decreased their viability and even induced apoptosis.…”

Value of pH regulators in the diagnosis, prognosis and treatment of cancer

“…However, there are only a few studies regarding the expression of NHE1 in human cancer samples and the clinicpathologic significance of NHE1 is also poorly explored. For instance, NHE1 has been shown to be overexpress in cervical cancer [131], hepatocellular carcinoma [132], esophageal adenocarcinomas [133], breast cancer [134] and glioblastomas [135] when compared with normal tissues. In cervical cancer, the expression of NHE1 was associated with tumour invasion and pelvic lymph node metastasis, whereas in hepatocellular carcinomas NHE1 expression was associated with increased tumour size, venous invasion and advanced tumour stage [131,132].…”

“…Melanoma [257] x tumour growth √ chemosensitization NHEs Amiloride Gliomas [146] Breast cancer [144] Esophageal cancer [133] Hepatocellular adenocarcinoma [132] Pancreas [258] x cell migration x cell invasion x cell proliferation √ chemosensitivity √ cell death Esophageal cancer [133] x tumour growth [147] Colorectal cancer [145] Gastric cancer [259] x cell proliferation √ cell death…”