Expression of V1A and GRP receptors leads to cellular transformation and increased sensitivity to substance-P analogue-induced growth inhibition

Abstract

Small-cell lung cancer (SCLC) is a particularly aggressive cancer, which metastasises early. Despite initial sensitivity to radio-and chemo-therapy, it invariably relapses, so that the 2-year survival remains less than 5%. Neuropeptides particularly arginine vasopressin (AVP) and gastrin-releasing peptide (GRP) act as autocrine and paracrine growth factors and the expression of these and their receptors are a hallmark of the disease. ,N me Phe 8 ]-substance-P (6 -11) (SP-G) inhibit the growth of SCLC cells by modulating neuropeptide signalling. We show that GRP and V 1A receptors expression leads to the development of a transformed phenotype. Addition of neuropeptide provides some protection from etoposide-induced cytotoxicity. Receptor expression also leads to an increased sensitivity to substance-P analogue-induced growth inhibition. We show that SP-D and SP-G act as biased agonists at GRP and V 1A receptors causing blockade of G q -mediated Ca 2 þ release while directing signalling to activate ERK via a pertussis toxin-sensitive pathway. This is the first description of biased agonism at V 1A receptors. This unique pharmacology governs the antiproliferative properties of these agents and highlights their potential therapeutic potential for the treatment of SCLC and particularly in tumours, which have developed resistance to chemotherapy.

Provasopressin expression by breast cancer cells: implications for growth and novel treatment strategies

“…It is possible then, that the expression of genes encoding neuropeptides and their receptors is a process associated with cellular immortalization. Recently, it was demonstrated that expression of the human V1a receptor in CHO cells resulted in a transformed phenotype that was associated with a loss of contact inhibited growth [41]. In apparent agreement with this notion, it was shown that activation of PI3K is essential for the transformation of human mammary epithelial cells in culture [42].…”

CD133+ Cancer Stem-like Cells in Small Cell Lung Cancer Are Highly Tumorigenic and Chemoresistant but Sensitive to a Novel Neuropeptide Antagonist

“…Expression of neuropeptides has been associated with neoplastic transformation (17), and there is evidence that lung CSC originates from neuroendocrine cells in the lung, which show an increased expression and response to neuropeptides (18)(19)(20)(21). We have shown that the development of chemoresistance to conventional chemotherapy in SCLC cells is accompanied by an increase in expression of neuropeptide receptors and subsequently increased sensitivity to broad-spectrum neuropeptide antagonists (22)(23)(24), suggesting that targeting neuropeptide receptors on SCLC cells may provide a new strategy to target chemoresistant disease.…”

“…The GLC14 and GLC16 cells were previously profiled by short tandem repeat profiling to confirm their origin from a single patient (25,26). GRP-R-and V 1A -Rexpressing CHO-K1 cells (23) were confirmed receptor positive by Western blot analysis. RPMI-1640, polyclonal rabbit antihuman AVP-R (V 1A ), was purchased from Chemicon International, rabbit anti-human GRP-R (Thermo Scientific), CD133/ 1-APC, CD133/2-PE, CD133/1, mouse IgG1-APC and mouse IgG1-PE (Miltenyi Biotec).…”

“…Cells were lysed as described previously (23) and equilibrated for protein using Pierce BCA protein assay reagent. Lysates were resolved on 12% SDS-PAGE gels and electroblotted onto nitrocellulose membranes.…”

“…For experimental purposes, SCLC cells were cultured in SITA medium consisting of RPMI-1640 medium supplemented with 30 nmol/L selenium, 5 mg/mL 1 insulin, 10 mg/mL 1 105 transferrin, and 0.25% (w/v) bovine serum albumin. CHO-K1 cells expressing the human GRP and V 1A receptors were cultured as we described previously (23).…”