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Biomedical subjects

S A Watson

Publications and source records attributed to S A Watson.

At least 19 recordsLinked to original sources
PubMed2003

Helicobacter pylori upregulates matrilysin (MMP-7) in epithelial cells in vivo and in vitro in a Cag dependent manner.

BACKGROUND AND AIMS: Matrix metalloproteinase-7 (MMP-7) is important in normal and pathological remodelling of epithelial-matrix interactions, and is upregulated in gastric cancer. Helicobacter pylori infection is the first stage in gastric carcinogenesis, and therefore our aim was to determine if H pylori upregulated gastric MMP-7 expression and if this was affected by strain virulence. METHODS: We took gastric biopsy specimens at endoscopy from H pylori infected (n = 17) and uninfected (n = 18) patients and assessed MMP-7 expression by ELISA, real time polymerase chain reaction (PCR), and immunohistochemistry (concentrating on epithelial cells in the proliferative zone). We PCR typed H pylori for cagE and vacA. We performed H pylori/cell line coculture studies with wild-type pathogenic and non-pathogenic H pylori strains and with CagE(-) and VacA(-) isogenic mutants. RESULTS: Gastric biopsy specimens from H pylori+ patients expressed higher levels of MMP-7 at the protein and mRNA levels in the antrum and corpus (for example, by ELISA: H pylori+ 0.182 OD units vH pylori- 0.059; p = 0.009 antrum). Epithelial cells from H pylori+ patients stained more intensely for MMP-7 than those from uninfected patients, including in the proliferative zone containing pluripotent cells (p<0.03 antrum, p<0.04 body). Upregulation of MMP-7 in epithelial cells was confirmed at the protein and mRNA levels by H pylori/cell line coculture. These experiments also showed that MMP-7 upregulation was dependent on an intact H pyloricag pathogenicity island but not on the vacuolating cytotoxin. CONCLUSION: We speculate that increased expression of MMP-7 in H pylori gastritis may contribute to gastric carcinogenesis.

Aged↗
PubMed2003

Potential role for peroxisome proliferator activated receptor (PPAR) in preventing colon cancer.

BACKGROUND: Peroxisome proliferator activated receptors (PPARs) are nuclear hormone receptors involved in genetic control of many cellular processes. PPAR and PPAR have been implicated in colonic malignancy. Here we provide three lines of evidence suggesting an inhibitory role for PPAR in colorectal cancer development. METHODS: Levels of PPAR mRNA and protein in human colorectal cancers were compared with matched non-malignant mucosa using RNAse protection and western blotting. APC(Min)/+ mice were randomised to receive the PPAR activator methylclofenapate 25 mg/kg or vehicle for up to 16 weeks, and small and large intestinal polyps were quantified by image analysis. The effect of methylclofenapate on serum stimulated mitogenesis (thymidine incorporation), linear cell growth, and annexin V and propidium iodide staining were assessed in human colonic epithelial cells. RESULTS: PPAR (mRNA and protein) expression levels were significantly depressed in colorectal cancer compared with matched non-malignant tissue. Methylclofenapate reduced polyp area in the small intestine from 18.7 mm(2) (median (interquartile range 11.1, 26.8)) to 9.90 (4.88, 13.21) mm(2) (p=0.003) and in the colon from 9.15 (6.31, 10.5) mm(2) to 3.71 (2.71, 5.99) mm(2) (p=0.009). Methylclofenapate significantly reduced thymidine incorporation and linear cell growth with no effect on annexin V or propidium iodide staining. CONCLUSIONS: PPAR may inhibit colorectal tumour progression, possibly via inhibition of proliferation, and may be an important therapeutic target.

Animals↗
PubMed2002

Potential role of endocrine gastrin in the colonic adenoma carcinoma sequence.

The role of hyper-gastrinaemia in the incidence of colonic cancer remains to be clarified. The aim of this study was to determine whether cholecystokinin-2 (CCK-2) receptor expression predicts the sensitivity of human colonic adenomas to the proliferative effects of serum hyper-gastrinaemia. Gene expression of the classical (74 kDa) CCK-2 receptor in human colonic adenoma specimens and cell lines, was quantified by real-time PCR. Western blotting, using a CCK-2 receptor antiserum, confirmed protein expression. A transformed human colonic adenoma was grown in SCID mice, with hyper-gastrinaemia induced by proton pump inhibitors. CCK-2 receptor blockade was achieved by using neutralising antiserum. Both human colonic adenoma cell lines and biopsies expressed CCK-2 receptor mRNA at levels comparable with CCK-2 receptor transfected fibroblasts and oxyntic mucosa. Western blotting confirmed immunoreactive CCK-2 receptor bands localised to 45, 74 and 82.5 kDa. Omeprazole and lansoprazole-induced hyper-gastrinaemia (resulting in serum gastrin levels of 34.0 and 153.0 pM, respectively) significantly increased the weight of the human adenoma grafts (43% (P=0.016) and 70% (P=0.014), respectively). The effect of hypergastrinaemia on tumour growth was reversed by use of antiserum directed against the CCK-2 receptor. Hyper-gastrinaemia may promote proliferation of human colonic adenomas that express CCK-2 receptor isoforms.

Adenocarcinoma↗
PubMed2002

Effect of preoperative radiotherapy on matrilysin gene expression in rectal cancer.

Matrilysin, a member of matrix metalloproteinase family, is believed to play a significant role in the growth and proliferation of colon cancer cells. Overexpression of the matrilysin gene has been shown to correlate with Dukes' stage and increased metastatic potential in colorectal cancer. The aim of this study was to evaluate the effect of preoperative high-dose radiotherapy (25 Gy in five fractions over 5 days) on matrilysin (MMP-7) gene expression, in patients with resectable rectal cancer, by a quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Biopsy samples of tumour (n=30) and distant normal mucosa (n=12) from 15 patients were obtained pre- and post-radiotherapy. Messenger (m)RNA was extracted from all of the tissue samples and reverse transcribed to double-stranded cDNA. Quantitative RT-PCR was performed to study the effect of preoperative radiotherapy on matrilysin gene expression in both the tumour and normal mucosal specimens. Matrilysin mRNA values were expressed relative to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) for each sample. In 14 out of 15 cases, matrilysin mRNA was detected in the cancerous tissue. Although all six normal mucosal specimens expressed matrilysin mRNA, the levels were approximately 10-fold lower compared with those seen in the paired tumour samples. Preoperative radiotherapy led to a significant 6- to 7-fold increase (P=0.001) in the expression of matrilysin mRNA in rectal cancer tissue. In contrast, there was no significant change in the matrilysin mRNA expression of normal mucosal specimens post-radiotherapy. Preoperative high-dose radiotherapy upregulates matrilysin gene expression in rectal cancer. Matrilysin inhibition may be a useful preventive or therapeutic adjunct to radiotherapy in rectal cancer.

Adenocarcinoma↗
PubMed2001

Antibodies raised against the extracellular tail of the CCKB/gastrin receptor inhibit gastrin-stimulated signalling.

INTRODUCTION: Gastrin acts to stimulate gastric acid secretion and is an acknowledged growth factor for human gastrointestinal (GI) cancer. The identity of the exact receptor type mediating the growth promoting effects of gastrin in tumours is uncertain. However, the best-characterised gastrin receptor is the CCK receptor type B (CCKB)/gastrin receptor. The anti-GRE1 antibody is a polyclonal, affinity-purified antibody raised against GRE1, a synthetic 21 amino acid peptide homologous to part of the extracellular, N-terminal tail of the CCKB receptor. We have recently proven that GRE1 antiserum specifically localises CCKB receptors on CCKB receptor transfected NIH3T3 cells and human gastrointestinal tumour cells by Western blotting and immunocytochemistry. GRE1 antiserum also inhibits liver invasion in the C170HM2 colorectal liver-metastasis model. AIM: To relate the ability of GRE1 antiserum to displace G17 from CCKB receptors with its impact on cellular transduction effects. METHODS: Radioligand binding studies were performed with 125IG17 and Calcium mobilisation studies by use of the fluorescent dye Fura 2-am. RESULTS: GRE1 antiserum competitively displaced 50% radiolabelled gastrin-17 from whole cell NIH3T3 CCKB transfectants at a protein concentration of 250 microg x ml(-1). GRE1 antiserum did not stimulate calcium ion influx in the transfectant NIH3T3 cells when used at a range of protein concentrations. Pre-incubation with GRE1 antiserum was required to inhibit gastrin-stimulated calcium ion influx. This was found to be concentration-dependent, with inhibition shown at 30 and 5 microg x ml(-1) but not at 500 ng x ml(-1) or below. CONCLUSION: The GRE1 antiserum is specific for the CCKB receptor and may act to inhibit gastrin-stimulated signalling in tumour cells.

3T3 Cells↗
PubMed2001

Spectrum of matrix metalloproteinase expression in primary and metastatic colon cancer: relationship to the tissue inhibitors of metalloproteinases and membrane type-1-matrix metalloproteinase.

The matrix metalloproteinases, MMP-2 and MMP-9, are capable of degrading components of the basement membrane, a vital barrier breached during the progression of colorectal cancer. The regulation of MMP-2 activation and subsequent targets is vital to understanding the metastatic process. MMP-2 was not expressed by colorectal cancer cells (C170 and C170HM(2)) in vitro but by stromal fibroblasts (46BR.1GI). There was induction of this MMP upon transwell co-cultivation of the colon cancer cells with the fibroblasts but in vivo growth did not lead to a similar increase in the metastatic tumour cells (C170HM(2)), MMP-2 again being attributed to the stromal cells. MMP-2 mRNA was overexpressed in human colorectal tumours compared to normal colorectal tissue, which correlated with Dukes' stage and immunolocalized to the stromal compartment of the tumour tissue. The active form of the MMP-2 enzyme was also present in the colorectal tumour tissue (7/8) but essentially absent in all normal colon samples examined (1/8). MMP-2 activation was not related to an increase in MT-1-MMP mRNA or a decrease in the specific inhibitor TIMP-2 in human tissue. There was however an increase in MMP-2/TIMP-2 ratio in tumour compared to normal. MMP-9, a target of active MMP-2, was present in the metastatic cell line but expression was down-regulated in the tumour cells in vivo, gelatin analysis revealed that MMP-9 was almost entirely attributable to the murine host, confirmed by PCR. There was no increase in mRNA for MMP-9 or its specific inhibitor TIMP-1 in colorectal tumour tissue compared to normal, MMP-9 protein localized to the inflammatory infiltrate. Fibroblast cells may provide malignant epithelial cells with a ready source of enzyme which is crucial to the metastatic process.

Colonic Neoplasms↗
PubMed2001

Effect of dietary GLA+/-tamoxifen on the growth, ER expression and fatty acid profile of ER positive human breast cancer xenografts.

Gamma linolenic acid (GLA) possesses a number of selective anti-tumour properties including modulation of steroid receptor structure and function. We have investigated the effect of dietary GLA on the growth, oestrogen receptor (ER) expression and fatty acid profile of ER+ve human breast cancer xenografts. Experimental diets A, B, C, D were commenced after subcutaneous implantation of 40 female nude mice with the MCF-7 B1M cell line (Group A = control diet: B = control diet + GLA supplement: C = control diet + tamoxifen: D = control diet + GLA + tamoxifen; 10 mice/group). The mice were terminated when tumour cross-sectional area reached 250 mm(2). ER H-scores were assessed by immunohistochemical assay and fatty acid profiles by gas-liquid chromatography of termination tumour samples. Groups C and D displayed significantly slower tumour growth (p =.0002, p =.0006) with trend for slower growth in B (p =.065) compared to control Group A. ER was significantly reduced in all groups compared to A (p <.0001) with Group D (combined therapy) displaying markedly lower ER expression than with either therapy alone (p =.0002). There were significantly raised levels of tumour GLA and metabolites in the two groups (B and D) receiving GLA (p <.0001). This xenograft model of ER+ve breast cancer has demonstrated significantly lower tumour ER expression in those groups receiving GLA, an effect which appears to be additive to the reduced ER expression resulting from tamoxifen alone. The effects of GLA on ER function and the possibility of synergistic inhibitory action of GLA with tamoxifen via enhanced down-regulation of the ER pathway require further investigation.

Animals↗
PubMed2001

Hypergastrinemia promotes adenoma progression in the APC(Min-/+) mouse model of familial adenomatous polyposis.

Serum hypergastrinemia promotes the growth of colorectal adenocarcinoma. Some colorectal adenomas express cholecystokinin B/gastrin receptor mRNA, and thus hypergastrinemia may increase progression through the adenoma-carcinoma sequence. This was investigated in the multiple intestinal neoplasia APC(Min-/+) mouse. Serum gastrin levels in APC(Min-/+) mice were elevated 5-6-fold by oral administration of omeprazole (75 mg/kg). Terminal tumor burden was monitored by onset of anemia. A labeling index was generated by immunohistochemical detection of bromodeoxyuridine incorporation. Serum gastrin was neutralized by antigastrin antibodies raised in situ by use of a gastrin immunogen, Gastrimmune. Hypergastrinemia resulted in reduced survival of the APC(Min-/+) mice from a median survival of 13 weeks in the controls to 10 weeks following omeprazole treatment (P < 0.00001, log-rank test). The labeling indices of adenomas from the small and large intestines of omeprazole-treated mice were increased 35 and 29%, respectively (P < 0.05 and P < 0.025, respectively). Gastrimmune immunization reversed both the survival effect and the increased proliferation resulting from serum hypergastrinemia. Hypergastrinemia may promote the progression of existing premalignant colonic lesions by increasing proliferation. Clinical investigations should determine whether this occurs in the human scenario, considering the widespread use of proton pump inhibitors.

Adenoma↗
PubMed2001

Gastrimmune-induced antigastrin-17 antibodies inhibit acid secretion in a rat fistula model.

BACKGROUND: Gastrimmune is an immunogenic form of gastrin. It raises in situ antibodies against two proliferative forms of gastrin: amidated and glycine-extended gastrin-17. It has been shown to have a therapeutic action in several in vivo tumour models. Following immunization, due to the complex equilibrium that exists between the antibodies and gastrin, it is not technically feasible to assay for free gastrin. AIM: To determine the effect of Gastrimmune-induced antigastrin antibodies on acid secretion. METHOD: A rat gastric fistula model was used. Animals (six per group) were immunized with a control immunogen or ascending doses of Gastrimmune. Acid output was measured following infusion of increasing doses of gastrin-17 and pentagastrin. RESULTS: Gastrimmune-induced antibodies significantly reduced gastrin-17-stimulated acid output compared to control animals (Gastrimmune at 200 microg/rat vs. control; acid output following 30 ng gastrin-17, 0.01 vs. 0.16, P < 0.001; following 120 ng gastrin-17, 0.022 vs. 0.29, P < 0.001). CONCLUSIONS: Gastrimmune significantly inhibits gastrin-17-stimulated acid output. This biological assay suggests that the antigastrin antibodies effectively bind gastrin-17. In addition to its use as an antineoplastic agent, Gastrimmune may have a role as an acid-decreasing agent in oesophagogastric pathology.

Animals↗
PubMed2001

Expression of gastrin in developing gastric adenocarcinoma.

BACKGROUND: A stepwise progression through premalignant stages has been identified for the intestinal type of gastric carcinoma. As gastrin has been identified as a growth factor for the intestinal type of gastric adenocarcinoma, the aim of this study was to investigate whether gastrin is expressed in premalignant gastric conditions. METHODS: Ninety archival samples of atrophic gastritis, intestinal metaplasia, mild gastric epithelial dysplasia, moderate gastric epithelial dysplasia, severe gastric epithelial dysplasia and intestinal-type gastric adenocarcinoma were obtained. Immunocytochemistry was performed using antibodies directed against gastrin and its post-translational precursors, and the gastrin/cholecystokinin B receptor. Positive staining was identified using the avidin--biotin immunoperoxidase method and quantified using an image analysis system. RESULTS: Gastrin and its receptor were shown to be expressed in specimens of atrophic gastritis, intestinal metaplasia, epithelial dysplasia and the intestinal type of gastric carcinoma. CONCLUSION: Gastrin seems to be an important growth factor in gastric carcinogenesis.

Adenocarcinoma↗
PubMed2001

G17DT--a new weapon in the therapeutic armoury for gastrointestinal malignancy.

G17DT or Gastrimmune, as it was formally known, is an antigastrin 17 immunogen producing neutralising high affinity antibodies directed against gastrin-17 (G17). Preclinical studies, initiated to identify biological functionality of G17DT-induced antibodies, confirmed that the antibodies both reduced G17 stimulated gastric acid secretion and inhibited gastrin from interacting with the CCK-2 receptor. Therapeutic efficacy of both passive and active immunisation with G17DT has been established in a number of tumour systems including both primary and metastatic disease. Furthermore, additive effects with 5-fluorouracil (5-FU)/leucovorin have been confirmed in both colon and gastric tumour models. Phase I/II studies in advanced gastrointestinal (GI) malignancies have shown no systemic or autoimmune reactions to active immunisation with G17DT. Use of an optimised dose has yielded a high proportion of responders (> 80%), with minimal side effects and antibody titres measurable within 2-4 weeks. Taken together these results suggest that the G17DT immunogen is a promising agent for the treatment of GI cancer and Phase III trials, currently underway, will definitively evaluate this early promise.

Adenocarcinoma↗
PubMed2000

Antiserum raised against an epitope of the cholecystokinin B/gastrin receptor inhibits hepatic invasion of a human colon tumor.

Serum gastrin is known to be elevated in patients with liver-metastasizing colon cancer; thus, cholecystokinin (CCK) B/gastrin receptors may also be up-regulated. A liver-invasive model of colon cancer was established with the human colonic cell line C170HM2, which expresses the CCKB/gastrin receptor at both the gene and protein level. An antiserum has been derived that is directed against the NH2-terminal 17 amino acids of the human CCKB/gastrin receptor coupled to diphtheria toxoid. The peptide was denoted gastrin receptor protein (GRP) 1. The therapeutic effect of GRP1 antiserum was evaluated on the liver invasion of C170HM2 tumors. Biodistribution studies revealed that GRP1 antiserum localized preferentially within the liver tumors when compared with normal liver tissue (1.5-fold increase after 24 h; P < 0.05). Antiserum against GRP1 inhibited both tumor take rate and final liver tumor weight when compared with treatment with control serum in mice with an increasing tumor burden. Liver tumor weights were reduced from 0.37 to 0.10 gram (P = 0.0155), 1.25 grams to 0.76 gram (P = 0.003) and 1.89 grams to 0.76 gram (P = 0.0068, all Mann-Whitney nonparametric U test). Necrosis and apoptosis were increased in the GRP1 antiserum-treated tumors when compared with control serum-treated tumors. As shown by Western blotting, CCKB/gastrin receptor expression of C170HM2 xenografts after treatment with GRP1 antiserum shifted to a predominantly lower molecular weight form (Mr 45,000) that is known to be an internalized form of the receptor. In conclusion, targeting of the CCKB/gastrin receptor may yield a valuable therapeutic modality for the treatment of advanced colon cancer.

Amino Acid Sequence↗
PubMed2000

Transforming growth factor-alpha-mediated growth pathways in human gastro-intestinal cell lines in relation to the gastrin autocrine pathway.

Epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) increase transcription of the gastrin gene, and the gastrin peptide may be phosphorylated by EGF-stimulated tyrosine kinase. Our aims were to compare EGF/TGF-alpha interactions in 2 human gastro-intestinal cell lines: MGLVA1, with a strong gastrin autocrine pathway, and C170HM2, with a weak pathway. Both cell lines expressed the TGF-alpha gene. MGLVA1 expressed TGF-alpha protein as determined by immuno-cytochemistry, which was absent in C170HM2. Both cell lines expressed the same level of EGF receptors, as assessed by flow cytometry; however, MGLVA1 did not have enhanced in vitro proliferation in response to EGF or TGF-alpha, unlike C170HM2. The basal growth of MGLVA1 was inhibited by anti-sera against TGF-alpha, the EGF receptor and G17. C170HM2 was not inhibited by any of the anti-sera. Neutralisation of TGF-alpha resulted in undetectable cell-associated progastrin levels in MGLVA1 (untreated had 391.7 fmol/5 x 10(6) cells). The progastrin level of C170HM2 remained unaffected. Tyrosine kinase activity, as assessed by phosphopeptide concentration, of unstimulated MGLVA1 was 2.6 times higher than that of C170HM2 in the cell membrane fraction (0.097 compared to 0.037 microg/mg protein, p < 0.001) and 4.8 times higher in the cytosolic fraction (0.269 compared to 0.056 microg/mg protein, p < 0.05). Following treatment with EGF, the phosphopeptide concentration increased in both the membrane and cytosolic fractions of both cell lines. Tyrphostin B42, which inhibits autophosphorylation of the EGF receptor, inhibited the basal growth of MGLVA1 (IC(50) 1.3 microM) and C170HM2 (9.5 microM, p < 0.05 from MGLVA1). Herbimycin, which inhibits pp60(c-src) kinase, reduced the basal growth of MGLVA1 (0.67 microM) but not C170HM2. Immunofluorescence studies confirmed the presence of tyrosine-phosphorylated proteins and pp60(c-src) within the cytoplasm of unstimulated MGLVA1 cells. There was no specific immunofluorescence for either parameter in C170HM2 cells until after treatment with EGF.

Blotting, Southern↗
PubMed2000

Review article: gastrin and colorectal cancer.

The polypeptide hormone gastrin was identified nearly a hundred years ago and its role in the regulation of acid secretion is well established. Gastrin also acts as a growth factor and is trophic for the normal gastric oxyntic mucosa. This growth promoting action has led to the extensive investigation of its role in carcinogenesis, in particular colorectal neoplasia. The relationship between gastrin and colorectal adenocarcinoma has been subject to controversy, however the findings from several recent studies have resulted in a clearer understanding of the mechanism of action of gastrin in this is common cancer. The majority of colorectal cancers produce their own gastrin, which may act in an autocrine manner. The tumour cells also express gastrin/CCKB receptors (and/or a combination of isoforms) which mediate the proliferative action. This locally produced gastrin gives rise to a small increase in systemic gastrin levels. Autocrine gastrin may also have a role in tumour development, as expression occurs early in the adenoma-carcinoma sequence. In addition, several studies using animal models have shown that systemic hypergastrinaemia promotes the proliferation of both normal and neoplastic colonic epithelium. Hyperproliferative colonic epithelium in the presence of hypergastrinaemia has been recorded in humans and a well-designed epidemiological study has demonstrated an increased incidence of colorectal cancer. Gastrin is a potential therapeutic target in the treatment of colorectal cancer and several approaches have been assessed. Receptor antagonists and antisecretory agents have been demonstrated to be ineffectual. Novel methods of inhibition, including the use of anti-gastrin antibodies, are currently being evaluated.

Amino Acid Sequence↗
PubMed2000

Increased type-IV collagenase (MMP-2 and MMP-9) activity following preoperative radiotherapy in rectal cancer.

The aim of this study was to investigate the effect of preoperative high-dose radiotherapy (25 Gy in 5 fractions over 5 days) on the type-IV collagenase protein profile, in patients with resectable rectal cancer, by gelatin zymography. Biopsy samples of tumour and distant normal mucosa from 12 patients with resectable rectal cancer were obtained pre- and post-radiotherapy. Expression of type-IV collagenases (both pro- and active forms) was studied using gelatin zymography. Enzyme levels were normalized for total protein content of each sample. Rectal cancer specimens expressed both pro (72 kDa) and active (62 kDa) forms of MMP-2 but only the pro form of MMP-9 (92 kDa). Normal mucosa showed expression of the pro forms of MMP-2 and MMP-9 while no active form of either enzyme was detected in any of the samples. A significant three- to fourfold increase (P < 0.01) of active matrix metalloproteinases (MMP)-2 (62 kDa) was seen in malignant rectal mucosa after radiotherapy. The effect of radiotherapy also led to a twofold increase (P = 0.047) of pro MMP-2 (72 kDa) and a two- to threefold increase (P = 0.03) of the precursor form of MMP-9 (92 kDa). In contrast, in normal mucosa expression of the precursor form of MMP-9 (92 kDa) did not change after radiation, and no significant effect on the levels of pro MMP-2 (72 kDa) was observed. Preoperative high-dose radiotherapy leads to an increase in activity of type-IV collagenases in patients with resectable rectal cancer. Type-IV collagenase inhibition may be a useful therapeutic adjunct to radiotherapy in rectal cancer.

Adenocarcinoma↗
PubMed2000

Gastrin and gastrin receptor activation: an early event in the adenoma-carcinoma sequence.

BACKGROUND AND AIMS: Gastrin and the cholecystokinin type B/gastrin receptor (CCKBR) have been shown to be expressed in colorectal adenocarcinoma. Both exogenous and autocrine gastrin have been demonstrated to stimulate growth of colorectal cancer but it is not known if gastrin affects the growth of colonic polyps. The purpose of this study was to determine if gastrin and CCKBR are expressed in human colonic polyps and to determine at which stage of progression this occurs. METHODS: A range of human colonic polyps was assessed for gastrin and CCKBR gene and protein expression. RESULTS: Normal colonic mucosa did not express gastrin or CCKBR. Gastrin and CCKBR reverse transcription-polymerase chain reaction products were detected and verified by specific hybridisation with an oligo probe on Southern blots. Gastrin and CCKBR were expressed in 78% and 81% of polyps, respectively. Both genes were coexpressed in 97% of cases. Immunohistochemistry identified progastrin in 91%, glycine extended gastrin 17 in 80%, and amidated gastrin 17 in only 47% of polyps. CCKBR was present in 96% of polyps. Expression of gastrin and CCKBR was seen in all histological types and sizes of polyps. CONCLUSIONS: This study is the first to show widespread expression of both gastrin and its receptor in colorectal polyps. Their activation occurs early in the adenoma-carcinoma sequence. Gastrin may promote progression through the adenoma-carcinoma sequence.

Adenoma↗