title: Tumor heterogeneity revealed by KRAS, BRAF, and PIK3CA pyrosequencing: KRAS and PIK3CA intratumor mutation profile differences and their therapeutic implications.
abstract: Current clinical problems in colorectal cancer (CRC) diagnostics and therapeutics include the disease complexity, tumor heterogeneity, and resistance to targeted therapeutics. In the present study, we examined 171 CRC adenocarcinomas from Greek patients undergoing surgery for CRC to determine the frequency of KRAS, BRAF, and PIK3CA point mutations from different areas of tumors in heterogeneous specimens. Ninety two out of 171 (53.8%) patients were found to bear a KRAS mutation in codons 12/13. Of the 126 mutations found, 57.9% (73/126) were c.38G>A mutations (p.G13D) and 22.2% (28/126) were c.35G>T (p.G12V). Remarkably, RAS mutations in both codons 12 and 13 were recorded in the same tumor by pyrosequencing. Moreover, differences in KRAS mutations between tumor center and periphery revealed tumor heterogeneity in 50.7% of the specimens. BRAF c.1799T>A (V600E) mutations were moderately detected in 4/171 (2.3%) specimens, whereas most PIK3CA mutations were revealed by pyrosequencing 6/171 (3.5%). Remarkable tumor heterogeneity is revealed, where double mutations of KRAS in the same tumor and different KRAS mutation status between tumor core and margin are detected with high frequency. It is expected that these findings will have a major impact in cancer diagnosis and personalized therapies.
authors.affiliation: Laboratory of Signal Mediated Gene Expression, Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, Athens, 11635, Greece.
authors.forename: Vivian
authors.initials: V
authors.lastname: Kosmidou
authors.forename: Eftychia
authors.initials: E
authors.lastname: Oikonomou
authors.forename: Margarita
authors.initials: M
authors.lastname: Vlassi
authors.forename: Spyros
authors.initials: S
authors.lastname: Avlonitis
authors.forename: Anastasia
authors.initials: A
authors.lastname: Katseli
authors.forename: Iraklis
authors.initials: I
authors.lastname: Tsipras
authors.forename: Despina
authors.initials: D
authors.lastname: Mourtzoukou
authors.forename: Georgios
authors.initials: G
authors.lastname: Kontogeorgos
authors.forename: Georgios
authors.initials: G
authors.lastname: Zografos
authors.forename: Alexander
authors.initials: A
authors.lastname: Pintzas
mesh_terms: D058534:Class I Phosphatidylinositol 3-Kinases; D003062:Codon; D015179:Colorectal Neoplasms / Q000235:genetics*; D004252:DNA Mutational Analysis; D005260:Female; D006801:Humans; D008297:Male; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics*; D017354:Point Mutation; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins / Q000235:genetics*
chemical_list: D003062:Codon; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D019869:Phosphatidylinositol 3-Kinases; D058534:Class I Phosphatidylinositol 3-Kinases; C484760:PIK3CA protein, human; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins
keywords: BRAF; KRAS; PIK3CA; colorectal cancer; tumor heterogeneity