APC, BRAF and KRAS mutations, and MLH1, MGMT and CDKN2A expression analysis in Nepalese colorectal cancer patients. : -

Abstract: Colorectal cancer (CRC) is a common malignancy which develops due to old age and lifestyle factors, low percent of patients afflicted by a genetic disorders. Half of all colorectal cancer patients are diagnosed after metastasis. The high rate of the late detection, emphasizes on the requirement of convenient and inexpensive diagnostic methods for comprehensive screening programs. The aim of this study was to discover proto-oncogenes mutation and assessment of tumor suppressor genes expression. Formalin fixed paraffin embedded (FFPE) histologically verified colorectal cancer samples were used. APC, KRAS and BRAF mutations were investigated using polymerase chain reaction (PCR) fragments and direct sequencing. Gene expression assessment of MLH1, MGMT and CDKN2A were achieved via quantitative polymerase chain reaction (qPCR). In the present study we could detect a novel transversion heterozygous mutation in APC gene codon 1365 in three patients. BRAF codon 600 mutation were detected in one patient. KRAS codon 12 mutation was discovered in one sample and also a novel transition mutation in codon 15 was detected in 6 patients. In 80% of cases, MLH1 and MGMT expression were undetectable, in remaining 20%, MLH1 expression were reduced, but MGMT showed both reduced and increased expression compared to control. In 100% of patients CDKN2A expression was undetectable. The rate of mutations in predetermined hotspot codons and amount of uncommon mutations into APC, BRAF and KRAS in Nepalese patients indicates the requirement of further investigation in CRC patients from that part of the world. Also, the expression rate of MLH1, MGMT, CDKN2A and deficiency of an information source emphasizes the necessity of whole genome CRC expression profiling data to comparison and conclusion.