Overexpression of membrane metalloendopeptidase inhibits substance P stimulation of cholangiocarcinoma growth

Abstract

Substance P (SP) promotes cholangiocyte growth during cholestasis by activating its receptor, NK1R. SP is a proteolytic product of tachykinin (Tac1) and is deactivated by membrane metalloendopeptidase (MME). This study aimed to evaluate the functional role of SP in the regulation of cholangiocarcinoma (CCA) growth. NK1R, Tac1, and MME expression and SP secretion were assessed in human CCA cells and nonmalignant cholangiocytes. The proliferative effects of SP (in the absence/presence of the NK1R inhibitor, L-733,060) and of L-733,060 were evaluated. In vivo, the effect of L-733,060 treatment or MME overexpression on tumor growth was evaluated by using a xenograft model of CCA in nu/nu nude mice. The expression of Tac1, MME, NK1R, PCNA, CK-19, and VEGF-A was analyzed in the resulting tumors. Human CCA cell lines had increased expression of Tac1 and NK1R, along with reduced levels of MME compared with nonmalignant cholangiocytes, resulting in a subsequent increase in SP secretion. SP treatment increased CCA cell proliferation in vitro, which was blocked by L-733,060. Treatment with L-733,060 alone inhibited CCA proliferation in vitro and in vivo. Xenograft tumors derived from MME-overexpressed human Mz-ChA-1 CCA cells had a slower growth rate than those derived from control cells. Expression of PCNA, CK-19, and VEGF-A decreased, whereas MME expression increased in the xenograft tumors treated with L-733,060 or MME-overexpressed xenograft tumors compared with controls. The study suggests that SP secreted by CCA promotes CCA growth via autocrine pathway. Blockade of SP secretion and NK1R signaling may be important for the management of CCA.

Mechanisms of cholangiocyte responses to injury

“…In cholestatic liver injury, elevated serum levels of SP are observed in patients with chronic liver disease as well as in cholestatic rat models compared to respective controls suggesting an association between SP production and cholestatic liver damage [60]. Elevated SP secretion is also identified in cholangiocarcinoma (CCA) cell lines and administration of NK-1R antagonist L-733, 060 inhibits proliferation of CCA cells [61]. A study has demonstrated that BDL mice show elevated NK-1R expression in large cholangiocytes, and NK-1R −/− mice show attenuated large cholangiocyte proliferation and bile duct hyperplasia [62].…”

Substance P increases liver fibrosis by differential changes in senescence of cholangiocytes and hepatic stellate cells

“…(5) Inhibition of SP secretion and NK-1R signaling decreases cholangiocarcinoma growth. (6) Knockout of NK-1R reduces cholangiocyte hyperplasia and expression of collagen type 1, alpha 1 (Col1a1) and asmooth muscle actin (a-SMA) in bile duct-ligated (BDL) mice. (7) There are in vivo studies showing that NK-1R antagonists not only suppress the secretion of proinflammatory cytokines in the liver but also protect liver cells from apoptosis.…”

Neuroendocrine Changes in Cholangiocarcinoma Growth

“…Human CCA lines, Mz-ChA-1, SG231, HuH-28, CCLP, and HuCCT1 cells, express higher levels of TAC1 and NK-1R compared to human normal cholangiocytes [82]. SP increased cell proliferation of these CCA cell lines, and administration of NK-1R antagonist, L-733,060, decreased Mz-ChA-1 cell proliferation in vitro as well as tumor size in Mz-ChA-1 xenograft nude mice in vivo [82]. Although NK-1R antagonists may be therapeutic in inhibiting CCA tumor growth, current studies are limited and expression levels of TAC1 and NK-1R in human CCA tumor tissues and correlation with metastases or survival rates are still undefined.…”

“…Administration of SP caused elevated ductular reaction and liver fibrosis in C57BL/6 wild-type mice, and NK-1R -/mice had improved liver conditions after BDL compared to wild-type mice with decreased HSC activation and fibrogenesis, indicating the association between the SP/NK-1R axis and cholestatic liver injury [81]. Human CCA lines, Mz-ChA-1, SG231, HuH-28, CCLP, and HuCCT1 cells, express higher levels of TAC1 and NK-1R compared to human normal cholangiocytes [82]. SP increased cell proliferation of these CCA cell lines, and administration of NK-1R antagonist, L-733,060, decreased Mz-ChA-1 cell proliferation in vitro as well as tumor size in Mz-ChA-1 xenograft nude mice in vivo [82].…”