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Targeted Knock‐in of the Polymorphism rs61764370 Does Not Affect KRAS Expression but Reduces let‐7 Levels
Author(s) -
Crowley Emily Hannah,
Arena Sabrina,
Lamba Simona,
Di Nicolantonio Federica,
Bardelli Alberto
Publication year - 2014
Publication title -
human mutation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 162
eISSN - 1098-1004
pISSN - 1059-7794
DOI - 10.1002/humu.22487
Subject(s) - kras , biology , microrna , oncogene , cancer research , untranslated region , three prime untranslated region , genetics , single nucleotide polymorphism , phenotype , cancer , gene , mutation , cell cycle , genotype , messenger rna
Understanding the role of single‐nucleotide polymorphisms ( SNP s) in the pathological process represents a unique experimental challenge especially when the variants occur outside of coding regions. The noncoding SNP rs61764370 located in the 3′‐untranslated region of K irsten rat sarcoma viral oncogene homolog ( KRAS ) has been implicated as a risk factor for the development of cancer and the response to targeted therapies. This cancer‐associated variant is thought to affect the binding of the micro RNA let‐7, which allegedly modulates KRAS expression. Using site‐specific homologous recombination, we inserted the rs61764370: T > G KRAS gene variant in the colorectal cancer cell line SW 48 ( SW 48 + SNP ) and assessed the cellular and biochemical phenotype. We observed a significant increase in cellular proliferation, as well as a reduction in the levels of the micro RNA let‐7a, let‐7b, and let‐7c. Transcriptional and biochemical analysis showed no concomitant change in the KRAS protein expression or modulation of the downstream mitogen activated kinase or PI 3 K / AKT signaling. These results suggest that the cancer‐associated rs61764370 variant exerts a biological effect not through transcriptional modulation of KRAS but rather by tuning the expression of the micro RNA let‐7.