Lack of mutation at codon 531 of SRC in advanced colorectal cancers from Italian patients

A truncating mutation (C to T transition) at codon 531 of the human protooncogene c-src, possibly accounting for the activation of c-src tyrosine kinase, has been recently identified in a subset of advanced colorectal cancer from North-American patients. However, two subsequent studies have failed to confirm the occurrence of SRC 531 mutation in colorectal cancers from North-European and Asiatic patients, raising the hypothesis that the genetic activation of src in colon cancer might be restricted to patients belonging to specific ethnic groups. We investigated a large series of colorectal cancers from Italian patients (155 cases) with a high prevalence of liver metastasis (43%). Using a PCR-RFLP assay, the occurrence of a SRC 531 mutation was ruled out in all the investigated specimens of primary tumours and/or metastases. Our results demonstrate that SRC Gln531AMB plays no role in the development or in the progression of colorectal cancer among Italian patients. © 2001 Cancer Research Campaign http://www.bjcancer.co

Common occurrence of multiple K-RAS mutations in pancreatic cancers with associated precursor lesions and in biliary cancers

Recent studies on small series of pancreatic cancer (PC) with foci of pancreatic intraepithelial neoplasia (PanIN), a putative precursor lesion, have shown that multiple K-RAS mutations may coexist in the same neoplastic pancreas. To see whether mutant-K-RAS polyclonality is a common and specific feature of pancreatic carcinogenesis, we investigated a unselected series of periampullary cancers (41 pancreatic, 13 biliary and two ampullary adenocarcinomas). After hemi-nested polymerase chain reaction (PCR), mutations identified with single strand conformation polymorphism (SSCP) were confirmed by allele-specific PCR and sequencing. K-RAS codon 12 was mutated in 34 (83%) pancreatic cancers and in 11 (85%) biliary cancers. Multiple distinct K-RAS mutations were found in 16 PC (39% of all cases, 47% of those with mutated K-RAS) and in eight biliary cancers (62 and 72%, respectively). In PC, multiple K-RAS mutations were more frequent (P<0.001) in cancers with (nine of 12, 75%) than in those without detectable PanIN (seven of 29, 24%). Individual precursor lesions of the same neoplastic pancreas were found to harbor distinct mutations. Results show that multiple K-RAS mutations are frequent both in PC with associated PanIN and in biliary cancers, and indicate that clonally distinct precursor lesions of PC might variably contribute to tumor development

Frameshift mutations of human gastrin receptor gene (hGARE) in gastrointestinal cancers with microsatellite instability

Gastrointestinal tumors with DNA mismatch repair (MMR) defects show microsatellite instability (MSI) and harbor frameshift mutations in coding mononucleotide repeats of cancer-related genes (targets). We assessed MSI status in 233 sporadic gastrointestinal tumors. We classified as MSI-H (high-frequency microsatellite instability) 15 (10%) of 150 colorectal cancers and 13 (16%) of 83 gastric cancers. We searched for frameshift mutations in a coding poly(T)(8) tract within the gastrin receptor gene (hGARE), which has a potential role in gastrointestinal carcinogenesis. To this purpose, we screened 43 unstable tumors (including 15 hereditary nonpolyposis colorectal cancer cases previously classified as MSI-H), 98 stable tumors, as well as 3 MMR-deficient and 4 MMR-proficient gastrointestinal cancer cell lines. We found mutations in 8 (19%) of the 43 MSI-H tumors but in none of the 98 stable cancers. hGARE mutation frequency was similar in gastric (23%) and colorectal cancers, including sporadic (13%) and hereditary (20%) cases. All mutated tumors proved to harbor frameshift mutations in other cancer-related genes that are considered as targets in MSI tumorigenesis. The MMR-deficient and gastrin-sensitive LoVo colorectal cancer cells also showed a hGARE heterozygous frameshift mutation, but expressed only the mutated allele. All detected mutations can be predicted to generate a truncated protein carrying amino acid changes. On the basis of genetic findings, we propose hGARE as a new candidate target gene in MSI tumorigenesis. Functional studies are warranted to elucidate the mechanism by which the hGARE mutation might contribute to gastrointestinal carcinogenesis

Frameshift mutations of human gastrin receptor gene (hGARE) in gastrointestinal cancers with microsatellite instability

Gastrointestinal tumors with DNA mismatch repair (MMR) defects show microsatellite instability (MSI) and harbor frameshift mutations in coding mononucleotide repeats of cancer-related genes (targets). We assessed MSI status in 233 sporadic gastrointestinal tumors. We classified as MSI-H (high-frequency microsatellite instability) 15 (10%) of 150 colorectal cancers and 13 (16%) of 83 gastric cancers. We searched for frameshift mutations in a coding poly(T)(8) tract within the gastrin receptor gene (hGARE), which has a potential role in gastrointestinal carcinogenesis. To this purpose, we screened 43 unstable tumors (including 15 hereditary nonpolyposis colorectal cancer cases previously classified as MSI-H), 98 stable tumors, as well as 3 MMR-deficient and 4 MMR-proficient gastrointestinal cancer cell lines. We found mutations in 8 (19%) of the 43 MSI-H tumors but in none of the 98 stable cancers. hGARE mutation frequency was similar in gastric (23%) and colorectal cancers, including sporadic (13%) and hereditary (20%) cases. All mutated tumors proved to harbor frameshift mutations in other cancer-related genes that are considered as targets in MSI tumorigenesis, The MMR-deficient and gastrin-sensitive LoVo colorectal cancer cells also showed a hGARE heterozygous frameshift mutation, but expressed only the mutated allele. All detected mutations can be predicted to generate a truncated protein carrying amino acid changes. On the basis of genetic findings, we propose hGARE as a new candidate target gene in MSI tumorigenesis. Functional studies are warranted to elucidate the mechanism by which the hGARE mutation might contribute to gastrointestinal carcinogenesis