BackgroundActivation of oncogenes downstream the EGFR gene contributes to colorectal tumorigenesis and determines the sensitivity to anti-EGFR treatments. The aim of this study was to evaluate the prognostic value of KRAS, BRAF, NRAS and PIK3CA mutations in a large collection of CRC patients from genetically-homogeneous Sardinian population.MethodsA total of 1284 Sardinian patients with histologically-proven diagnosis of colorectal carcinoma (CRC) and presenting with metastatic disease were included into the study. Genomic DNA was isolated from formalin-fixed, paraffin-embedded primary tumour tissue samples of CRC patients and screened for mutations in RAS and BRAF genes, using pyrosequencing assays, and in PIK3CA gene, using automated DNA sequencing assays.ResultsOverall, mutation rates were 35.6 % for KRAS, 4.1 % for NRAS, and 2.1 % for BRAF. Among available DNA samples, 114/796 (14.3 %) primary CRCs were found to carry a mutation in the PIK3CA gene. In this subset of patients analysed in all four genes, a pathogenetic mutation of at least one gene was discovered in about half (378/796; 47.5 %) of CRC cases. A mutated BRAF gene was found to steadily act as a negative prognostic factor for either time to progression as metastatic disease (from detection of primary CRC to diagnosis of first distant metastasis; p = 0.009) or partial survival (from diagnosis of advanced disease to the time of death or last control; p = 0.006) or overall survival (p < 0.001). No significant impact on prognosis was observed for mutated KRAS, NRAS, and PIK3CA genes or combined RAS mutations (all RAS).ConclusionsOur study defines both prevalence and prognostic role of main activated oncogenes in a population-based large collection of CRC patients.Electronic supplementary materialThe online version of this article (doi:10.1186/s12967-016-1053-z) contains supplementary material, which is available to authorized users.
Planococcus ficus (Signoret) and Planococcus citri (Risso) (Hom., Pseudococcidae) are important phytophagous components in different agroecosystems. The two species may coexist in the same environment and are most difficult to distinguish by morphological features. The aim of this study was to find genetic markers suitable for distinguishing P. ficus from P. citri, to assist in the rapid identification of field specimens. By using synthetic sex pheromone-baited traps, pure male populations of both species were collected from a vineyard and from a citrus orchard in northern Sardinia, Italy. Individual males of citrus and vine mealybugs were preliminarily examined by the random amplification of polymorphic DNA (RAPD) technique. Among twelve 10-mer random primers, the oligonucleotide OPL-12 generated several markers suitable for distinguishing between the two species. This primer was then used to characterize individual males and females of both mealybug species collected near pheromone-baited traps in vineyards and orange orchards from different geographic areas. Reference samples from other regions of southern Italy were also included. A clear differentiation of the two species was accomplished according to their pattern of amplification, thus confirming a high level of intra-specific genetic homogeneity. Consequently, two fragments of the cytochrome c oxidase I gene from P. citri and P. ficus were compared and two pairs of species-specific polymerase chain reaction (PCR) primers were developed based on diverging sequences. These primers allowed sensitive and reliable PCR identification of both males and females of P. citri and of P. ficus of different geographic origin.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.