Expression of mRNA for Gastrin-Releasing Peptide Receptor by Human Bronchial Epithelial Cells

Abstract

Bombesin-like peptides (BLPs) are important regulators of lung development and may also act as autocrine growth factors in lung tumors. We have previously demonstrated expression of mRNA for the three BLP receptor subtypes (neuromedin B [NMB]) receptor, gastrin-releasing peptide [GRP] receptor, and bombesin receptor subtype 3 [BRS-3]) in human non-small cell lung carcinoma (NSCLC) cell lines and bronchial biopsies using the reverse transcription-polymerase chain reaction (RT-PCR; DeMichele, et al. Am. J. Respir. Cell Mol. Biol. 1994; 11:66-74). We have also previously found that growth responses to BLPs could be elicited in some, but not all, cultures of human bronchial epithelial (HBE) cells (Siegfried, et al. Anat. Rec. 1993; 236:241-247). In this report, we utilized RT-PCR to demonstrate mRNA expression of BLP receptor subtypes in cultured HBE cells and also assessed the response of these cultures to BLPs in proliferation assays. The pattern of mRNA expression was correlated with proliferative response, and the results were also analyzed in relation to smoking history and pulmonary function of the subjects studied. Our results suggest that expression of mRNA for the GRP receptor is associated with a long smoking history (> 25 pack-years [PY], p = 0.02). This association was related to past tobacco exposure, regardless of whether the subjects were still active smokers at the time of tissue procurement. Responsiveness to GRP and NMB in proliferation assays was also found only in those HBE cultures with expression of mRNA for at least one of the known receptors for BLPs, and there was a significant association between expression of mRNA for the GRP receptor and proliferative response to both GRP and NMB (p = 0.048). HBE cultures from subjects with a greater than 25 PY smoking history were also more likely to respond to BLPs in the proliferation assays than cells from subjects with less than a 25 PY history (10 of 16 versus 1 of 7, p = 0.06). Cultures of HBE cells from four of the five subjects with severe obstructive lung disease gave a positive response to GRP and NMB in proliferation assays, compared to five of fifteen without severe obstructive lung disease, but this difference was not significant (p = 0.13). These results suggest there is an increased likelihood of expression of the GRP receptor mRNA in the respiratory epithelium of some individuals with a history of prolonged tobacco exposure, and that expression of the GRP receptor mRNA is accompanied by responsiveness to the mitogenic effects of BLPs. These effects appear to persist after smoking cessation.

Growth inhibition of non-small-cell lung carcinoma by BN/GRP antagonist is linked with suppression of K-Ras, COX-2, and pAkt

“…An antiproliferative effect of BN/GRP antagonists against NSCLC has not been demonstrated previously (2, 7). Because GRP also was postulated to be an autocrine growth factor for NSCLC (23) and because many NSCLC cell lines express receptors for BN/GRP (4,5), the aim of this study was to demonstrate the efficacy of BN/GRP antagonist RC-3940-II in the treatment of human NSCLC.…”

“…Subsequently, it was shown that BN/GRP also stimulates cell proliferation of other neoplasms, such as breast cancer and NSCLC (2,4). Several subtypes of receptors for BN/GRP are present in NSCLC cell lines, including A549 and H460 (4,5). In an endeavor to develop a new class of anticancer agents, various antagonistic analogues of BN/GRP were synthesized in our institute (2,6).…”

International Union of Pharmacology. LXVIII. Mammalian Bombesin Receptors: Nomenclature, Distribution, Pharmacology, Signaling, and Functions in Normal and Disease States

“…NMB is an autocrine growth factor for non-small cell lung cancer with 14 of 14 such cell lines possessing BB 1 receptors in one study (Siegfried et al, 1997), and in four non-small cell lung cancer cell lines examined in detail NMB was synthesized and released into the media by the tumor cell in 7 to 15 times greater amounts than was GRP (Siegfried et al, 1997). Blockade of the BB 2 receptor only partially blocked the proliferative effect of NMB on these cells, demonstrating the importance of BB 1 receptor activation for the proliferative effects in these tumor cells (Siegfried et al, 1997). Furthermore, in human colon cancers NMB and the BB 1 receptor are coexpressed, and they act in an autocrine growth fashion (Matusiak et al, 2005).…”

“…Using binding studies and/or assessment of BB 1 mRNA, BB 1 receptors have been shown to exist on a large number of different tumors (Reubi et al, 2002;Jensen and Moody, 2006) including CNS tumors (glioblastomas) Wang et al, 1992), small cell and non-small cell lung cancers Moody et al, 1992Moody et al, , 2000Toi-Scott et al, 1996;Siegfried et al, 1997;Jensen and Moody, 2006), carcinoids (intestinal, thymic, and bronchial) (Reubi et al, 2002), human ovarian epithelial cancers (Sun et al, 2000b), and pancreatic cancer cell lines (Jensen and Moody, 2006 (Moody et al, 1992;Benya et al, 1995b;Reubi et al, 2002) as well as the rat BB 1 receptor (von Schrenck et al, 1989(von Schrenck et al, , 1990Wang et al, 1992;Ladenheim et al, 1992Ladenheim et al, , 1993a) has a Ͼ100-fold higher affinity for NMB than for GRP (Fig. 1, Table 1).…”

STAT signaling in head and neck cancer

“…The acquisition in vitro of such an autocrine pathway has enabled cells of several lineages to be transformed from the normal to malignant phenotype (Roberts and Sporn, 1985). Examples of autocrine growth pathways in cancer include gastrin-releasing peptide (GRP)/neuromedin B and GRP-receptor in lung cancer (Siegfried et al, 1993(Siegfried et al, , 1997DeMichele et al, 1994), ®broblast growth factor (bFGF) and FGF-receptor (FGFR-1) in melanoma (Becker et al, 1989(Becker et al, , 1992 and HER2-neu in breast cancer (for review see Earp et al, 1995).…”