Progastrin expression predisposes mice to colon carcinomas and adenomas in response to a chemical carcinogen

doi:10.1053/gast.2000.8527

Gastroenterology

Volume 119, Issue 1, July 2000, Pages 162-171

https://doi.org/10.1053/gast.2000.8527 Get rights and content

Abstract

Background & Aims: Processing intermediates of preprogastrin (gly-gastrin and progastrin), termed nonamidated gastrins, are mitogenic for several cell types including colonic epithelial cells. However, presently it is not known if nonamidated gastrins play a role in colon carcinogenesis and if the effects are similar to those of amidated gastrins. Methods: Colon carcinogenesis in response to azoxymethane (AOM) was examined in transgenic mice overexpressing either progastrin (hGAS) or amidated gastrin (INS-GAS), compared with that in wild-type (WT) mice. Results: In AOM-treated groups, the total number of tumors per colon was significantly higher in hGAS (4.8 ± 0.34) than INS-GAS (3.0 ± 0.16) and WT (2.7 ± 0.35) mice. Total numbers of adenocarcinomas and adenomas per animal colon were also significantly higher in hGAS than INS-GAS and WT mice. The size of the tumors was greater in hGAS mice, resulting in a significantly higher tumor burden per mouse in the hGAS mice than INS-GAS and WT mice. Although >90% of the tumors were located in the distal half of the colon in INS-GAS and WT mice, a significant number (42%) were present at the proximal end of the colon in hGAS mice. Conclusions: The results suggest that the risk for developing colon carcinomas and adenomas in response to AOM is significantly increased in mice expressing high levels of progastrin, but not amidated gastrins.

GASTROENTEROLOGY 2000;119:162-171

Section snippets

Animals

Transgenic hGAS and INS-GAS in the FVB/N background and control FVB/N mice were used in the study as described previously.³⁹ Transgenic and WT mice were age and sex matched, had similar body weights, and were raised in a common facility in Massachusetts General Hospital (MGH). The generation and characteristics of the hGAS and INS-GAS mice have been described previously in detail.²⁸ The hGAS transgenic mice contain a human gastrin minigene, resulting in overexpression of gastrin in mouse

Effect of AOM treatment on relative survival of hGAS, INS-GAS, and WT mice

The mice were treated with the optimal dose of AOM (12 mg · kg body wt⁻¹ · wk⁻¹) for either 4 weeks or 3 weeks as described in Materials and Methods. At the start of the experiments, all animals were ~7-8 weeks old and their body weights, on an average, were 22-26 g. The body weight of all mice in all groups of treated and control animals increased by 5%-10% in the initial 4-6 weeks of the study and plateaued thereafter. In these experiments, we measured body weights at intervals of 2-3 weeks

Discussion

The results of these studies with transgenic mice that overexpress progastrin provide strong evidence that increased progastrin levels can function as a cocarcinogen and significantly augment the carcinogenic potential of chemical carcinogens such as AOM. The role of hypergastrinemia in colon carcinogenesis in rodents and humans has remained a confusing and controversial area.31, 32, 33, 34, 42, 43, 44, 45, 46 Experimental models that resulted in increased levels of circulating amidated

References (49)

KW Kinzler et al.
Lessons from hereditary colorectal cancer
Cell
(1996)
LR Johnson
New aspects of the trophic action of gastrointestinal hormones
Gastroenterology
(1977)
KR Sirinek et al.
Pentagastrin stimulates in vitro growth of normal and malignant human colon epithelial cells
Am J Surg
(1985)
WW Van Solinge et al.
Expression but incomplete maturation of progastrin in colorectal carcinomas
Gastroenterology
(1993)
Z Xu et al.
Gastrin gene expression in human colon cancer cells measured by a simple competitive PCR method
Life Sci
(1994)
F Hollande et al.
Glycine-extended gastrin acts as an autocrine growth factor in a nontransformed colon cell line
Gastroenterology
(1997)
ML Kochman et al.
Post-translation processing of gastrin in neoplastic human colonic tissues
Biochem Biophys Res Commun
(1992)
GD Ciccotosto et al.
Expression, processing, and secretion of gastrin in patients with colorectal carcinoma
Gastroenterology
(1995)
P Singh et al.
Novel gastrin receptors mediate mitogenic effects of gastrin processing intermediates of gastrin on Swiss 3T3 fibroblasts
J Biol Chem
(1995)
TJ Koh et al.
Gastrin deficiency results in altered gastric differentiation and decreased colonic proliferation in mice
Gastroenterology
(1997)

DA Karlin et al.

Hypergastrinemia and colorectal carcinogenesis in the rat

Cancer Lett

(1985)

DM Pinson et al.

Drug-induced hypergastrinemia: absence of trophic effects on colonic carcinoma in rats

Gastroenterology

(1995)

L Roncucci et al.

Identification and quantification of aberrant crypt foci and microadenomas in the human colon

Hum Pathol

(1991)

CM Thorburn et al.

Gastrin and colorectal cancer: a prospective study

Gastroenterology

(1998)

H Nakata et al.

Oncogenic ras induces gastrin gene expression in colon cancer

Gastroenterology

(1998)

EP Kennedy et al.

Genetics of colorectal cancer

Semin Surg Oncol

(1998)

MG Brattain et al.

Growth factor balance and tumor progression

Curr Opin Oncol

(1994)

BS Reddy

Nutritional factors and colon cancer

Crit Rev Food Sci Nutr

(1995)

P Singh et al.

Role of autocrine and endocrine gastrin-like peptides in colon cancers

Curr Opin Gastroenterol

(2000)

M Lipkin

Biomarkers of increased susceptibility to gastrointestinal cancer: New application to studies of cancer prevention in human subjects

Cancer Res

(1988)

JH Walsh

Gastrin

TC Wang et al.

Lessons from genetically engineered animal models. I. Physiological studies with gastrin in transgenic mice

Am J Physiol

(1999)

P Singh et al.

Hormones in colon cancer; past and prospective studies

Cancer J

(1990)

Cited by (101)

Molecular pathogenesis, targeted therapies, and future perspectives for gastric cancer
2022, Seminars in Cancer Biology
Gastric cancer is a major source of global cancer mortality with limited treatment options and poor patient survival. As our molecular understanding of gastric cancer improves, we are now beginning to recognize that these cancers are a heterogeneous group of diseases with incredibly unique pathogeneses and active oncogenic pathways. It is this molecular diversity and oftentimes lack of common oncogenic driver mutations that bestow the poor treatment responses that oncologists often face when treating gastric cancer. In this review, we will examine the treatments for gastric cancer including up-to-date molecularly targeted therapies and immunotherapies. We will then review the molecular subtypes of gastric cancer to highlight the diversity seen in this disease. We will then shift our discussion to basic science and gastric cancer mouse models as tools to study gastric cancer molecular heterogeneity. Furthermore, we will elaborate on a molecular process termed paligenosis and the cyclical hit model as key events during gastric cancer initiation that impart nondividing mature differentiated cells the ability to re-enter the cell cycle and accumulate disparate genomic mutations during years of chronic inflammation and injury. As our basic science understanding of gastric cancer advances, so too must our translational and clinical efforts. We will end with a discussion regarding single-cell molecular analyses and cancer organoid technologies as future translational avenues to advance our understanding of gastric cancer heterogeneity and to design precision-based gastric cancer treatments. Elucidation of interpatient and intratumor heterogeneity is the only way to advance future cancer prevention, diagnoses and treatment.
Progastrin production transitions from Bmi1+/Prox1+ to Lgr5high cells during early intestinal tumorigenesis
2021, Translational Oncology
Progastrin is an unprocessed soluble peptide precursor with a well-described tumor-promoting role in colorectal cancer. It is expressed at small levels in the healthy intestinal mucosa, and its expression is enhanced at early stages of intestinal tumor development, with high levels of this peptide in hyperplastic intestinal polyps being associated with poor neoplasm-free survival in patients. Yet, the precise type of progastrin-producing cells in the healthy intestinal mucosa and in early adenomas remains unclear. Here, we used a combination of immunostaining, RNAscope labelling and retrospective analysis of single cell RNAseq results to demonstrate that progastrin is produced within intestinal crypts by a subset of Bmi1⁺/Prox1⁺/LGR5^low endocrine cells, previously shown to act as replacement stem cells in case of mucosal injury. In contrast, our findings indicate that intestinal stem cells, specified by expression of the Wnt signaling target LGR5, become the main source of progastrin production in early mouse and human intestinal adenomas. Collectively our results suggest that the previously identified feed-forward mechanisms between progastrin and Wnt signaling is a hallmark of early neoplastic transformation in mouse and human colonic adenomas.
The application of transgenic and gene knockout mice in the study of gastric precancerous lesions
2018, Pathology Research and Practice
Gastric intestinal metaplasia is a precursor for gastric dysplasia, which is in turn, a risk factor for gastric adenocarcinoma. Gastric metaplasia and dysplasia are known as gastric precancerous lesions (GPLs), which are essential stages in the progression from normal gastric mucosa to gastric cancer (GC) or gastric adenocarcinoma. Genetically-engineered mice have become essential tools in various aspects of GC research, including mechanistic studies and drug discovery. Studies in mouse models have contributed significantly to our understanding of the pathogenesis and molecular mechanisms underlying GPLs and GC. With the development and improvement of gene transfer technology, investigators have created a variety of transgenic and gene knockout mouse models for GPLs, such as H/K-ATPase transgenic and knockout mutant mice and gastrin gene knockout mice. Combined with Helicobacter infection, and treatment with chemical carcinogens, these mice develop GPLs or GC and thus provide models for studying the molecular biology of GC, which may lead to the discovery and development of novel drugs. In this review, we discuss recent progress in the use of genetically-engineered mouse models for GPL research, with particular emphasis on the importance of examining the gastric mucosa at the histological level to investigate morphological changes of GPL and GC and associated protein and gene expression.
A novel antibody against cancer stem cell biomarker, DCLK1-S, is potentially useful for assessing colon cancer risk after screening colonoscopy
2017, Laboratory Investigation
DCLK1 expression is critically required for maintaining growth of human colon cancer cells (hCCCs). Human colorectal tumors (CRCs) and hCCCs express a novel short isoform of DCLK1 (DCLK1-S; isoform 2) from β-promoter of hDCLK1 gene, while normal colons express long isoform (DCLK1-L; isoform 1) from 5′(α)-promoter, suggesting that DCLK1-S, and not DCLK1-L, marks cancer stem cells (CSCs). Even though DCLK1-S differs from DCLK1-L by only six amino acids, we succeeded in generating a monospecific DCLK1-S-Antibody (PS41014), which does not cross-react with DCLK1-L, and specifically detects CSCs. Subcellular localization of S/L-isoforms was examined by immune-electron-microscopy (IEM). Surprisingly, besides plasma membrane and cytosolic fractions, S/L also localized to nuclear/mitochondrial fractions, with pronounced localization of S-isoform in the nuclei and mitochondria. Sporadic CRCs develop from adenomas. Screening colonoscopy is used for detection/resection of growths, and morphological/pathological criteria are used for risk assessment and recommendations for follow-up colonoscopy. But, these features are not precise and majority of the patients will never develop cancer. We hypothesized that antibody-based assay(s), which identify CSCs, will significantly improve prognostic value of morphological/pathological criteria. We conducted a pilot retrospective study with PS41014-Ab, by staining archived adenoma specimens from patients who developed (high-risk), or did not develop (low-risk) adenocarcinomas within 10–15 years. PS41014-Ab stained adenomas from initial and follow-up colonoscopies of high-risk patients, at significantly higher levels (three to fivefold) than adenomas from low-risk patients, suggesting that PS41014-Ab could be used as an additional tool for assessing CRC risk. CRC patients, with high DCLK1-S-expressing tumors (by qRT-PCR), were reported to have worse overall survival than low expressers. We now report that DCLK1-S-specific Ab may help to identify high-risk patients at the time of index/screening colonoscopy.
Progastrin-induced secretion of insulin-like growth factor 2 from colonic myofibroblasts stimulates colonic epithelial proliferation in mice
2013, Gastroenterology
Many colon cancers produce the hormone progastrin, which signals via autocrine and paracrine pathways to promote tumor growth. Transgenic mice that produce high circulating levels of progastrin (hGAS) have increased proliferation of colonic epithelial cells and are more susceptible to colon carcinogenesis than control mice. We investigated whether progastrin affects signaling between colonic epithelial and myofibroblast compartments to regulate tissue homeostasis and cancer susceptibility.
Colonic myofibroblast numbers were assessed in hGAS and C57BL/6 mice by immunohistochemistry. Human CCD18Co myofibroblasts were incubated with recombinant human progastrin (rhPG)(1–80) for 18 hours, and proliferation was assessed in the presence of pharmacologic inhibitors. The proliferation of human HT29 colonic epithelial cells was assessed after addition of conditioned media from CCD18Co cells incubated with progastrin. The effects of the insulin-like growth factor (IGF)-I receptor antagonist AG1024 were investigated in cultured HT29 cells and on the colonic epithelium of hGAS mice compared with mice that did not express transgenic progastrin (controls).
The colonic mucosa of hGAS mice contained greater numbers of myofibroblasts that expressed α–smooth muscle actin and vimentin than controls. Incubation of CCD18Co myofibroblasts with 0.1 nmol/L rhPG(1–80) increased their proliferation, which required activation of protein kinase C and phosphatidylinositol-3 kinase. CCD18Co cells secreted IGF-II in response to rhPG(1–80), and conditioned media from CCD18Co cells that had been incubated with rhPG(1–80) increased the proliferation of HT29 cells. The colonic epithelial phenotype of hGAS mice (crypt hyperplasia, increased proliferation, and altered proportions of goblet and enteroendocrine cells) was inhibited by AG1024.
Progastrin stimulates colonic myofibroblasts to release IGF-II, which increases proliferation of colonic epithelial cells. Progastrin might therefore alter colonic epithelial cells via indirect mechanisms to promote neoplasia.
Gastrin in gastrointestinal diseases
2011, Gastroenterology

View all citing articles on Scopus

^☆: Address requests for reprints to: Pomila Singh, Ph.D., Department of Anatomy and Neurosciences, 10.138 Medical Research Building, University of Texas Medical Branch, Galveston, Texas 77555-1043. e-mail: [email protected]; fax: (409) 772-3222.

^☆☆: Supported by grants CA60087 and CA72992 (to P.S.) and DK52778 (to T.C.W.) from the National Institutes of Health.

View full text

Alimentary TractProgastrin expression predisposes mice to colon carcinomas and adenomas in response to a chemical carcinogen☆,☆☆

Abstract

Section snippets

Animals

Effect of AOM treatment on relative survival of hGAS, INS-GAS, and WT mice

Discussion

Cell

Gastroenterology

Am J Surg

Gastroenterology

Life Sci

Gastroenterology

Biochem Biophys Res Commun

Gastroenterology

J Biol Chem

Gastroenterology

Cancer Lett

Gastroenterology

Hum Pathol

Gastroenterology

Gastroenterology

Genetics of colorectal cancer

Semin Surg Oncol

Growth factor balance and tumor progression

Curr Opin Oncol

Nutritional factors and colon cancer

Crit Rev Food Sci Nutr

Role of autocrine and endocrine gastrin-like peptides in colon cancers

Curr Opin Gastroenterol

Biomarkers of increased susceptibility to gastrointestinal cancer: New application to studies of cancer prevention in human subjects

Cancer Res

Gastrin

Lessons from genetically engineered animal models. I. Physiological studies with gastrin in transgenic mice

Am J Physiol

Hormones in colon cancer; past and prospective studies

Cancer J

Alimentary Tract
Progastrin expression predisposes mice to colon carcinomas and adenomas in response to a chemical carcinogen☆,☆☆