| First Author | Luo F | Year | 2014 |
| Journal | Int J Exp Pathol | Volume | 95 |
| Issue | 1 | Pages | 8-15 |
| PubMed ID | 24354449 | Mgi Jnum | J:312156 |
| Mgi Id | MGI:6782978 | Doi | 10.1111/iep.12064 |
| Citation | Luo F, et al. (2014) Wild-type K-ras has a tumour suppressor effect on carcinogen-induced murine colorectal adenoma formation. Int J Exp Pathol 95(1):8-15 |
| abstractText | K-ras mutations are found in ~40% of human colorectal adenomas and carcinomas and contribute to colorectal tumour formation at an early stage. Wild-type K-ras has been reported to be deleted in some tumours, but the consequences of changes in wild-type K-ras copy number for experimental colorectal carcinogenesis have not been investigated. To characterize the effects of K-ras copy number changes on formation of carcinogen-induced colorectal neoplasms in mice, wild-type (K-ras(+/+) ) and heterozygous K-ras exon 1 knockout (K-ras(+/-) ) mice were given 10 weekly treatments of 1, 2-dimethylhydrazine (DMH) to induce colorectal tumours. Colorectal expression levels of K-ras 4A and 4B transcripts in K-ras(+/-) mice were ~50% decreased compared with K-ras(+/+) mice. One year after DMH treatment, survival of K-ras(+/-) mice decreased from 88 to 82% compared with wild-type mice. Colorectal adenomas significantly increased from 0.52 +/- 0.15 in K-ras(+/+) mice to 0.87 +/- 0.14 in K-ras(+/-) mice (mean +/- SEM per mouse, P < 0.01); total tumour volume increased 2.13-fold (P < 0.05). Comparing K-ras(+/+) with K-ras(+/-) murine adenomas, Ki-67-positive proliferating tumour cells significantly increased from 7.77 +/- 0.64% to 9.15 +/- 0.92% and cleaved caspase-3-positive apoptotic tumour cells decreased from 1.40 +/- 0.37% to 0.80 +/- 0.22% (mean +/- SEM, P < 0.05 for both). No K-ras or B-raf mutations were detected in the adenomas. Immunohistochemical studies showed no significant changes in extracellular signal regulating kinase/mitogen-activated protein kinase (Erk/MapK) or PI3K/Akt pathway activation in the adenomas. In conclusion, the data collectively show that a 50% reduction in K-ras gene dosage and RNA expression promoted experimental colorectal tumourigenesis, consistent with wild-type K-ras having a tumour suppressor effect on carcinogen-induced murine colorectal adenoma formation. |
