Numerous clinical studies have shown that anti-EGFR therapies are effective only in a subset of patients with colorectal cancer. Even though mutations in the KRAS gene have been confirmed as negative predictors of the response to EGFR-targeted therapies, not all KRAS wild-type (wt-KRAS) patients will respond to treatment. Recent studies have demonstrated that additionally wild-type BRAF (wt-BRAF) genotype is required for response to panitumumab or cetuximab, suggesting that BRAF genotype criteria should be used together with KRAS genotype for selecting the patients who are about to benefit from the anti-EGFR therapy. In this study, 239 samples obtained from 215 patients with metastatic colorectal cancer were tested for the presence of the seven most common mutations in the KRAS gene and the V600E mutation in the BRAF gene. Among the tested patients, 53.8% of patients had wt-KRAS genotype and 46.2% were KRAS mutants. Around five percent (5.1%) of the tested patients bore the V600E mutation in BRAF gene. All the patients showing to have the V600E mutation in BRAF were wt-KRAS. The concordance of KRAS and BRAF mutational status between primary and metastatic tumor tissue samples was 100%. We have shown that the proportions of mutated and non-mutated KRAS in Slovene patients, as well as the proportion of V600E mutations in BRAF is similar to genotyping results reported by other authors. The tested seven KRAS mutations on codons 12 and 13 were mutually exclusive with the V600E mutation in the BRAF gene. Summing up the results about the KRAS and the BRAF mutation carriers from our study, the portion of potentially non-responsive patients for the anti-EGFR treatment is 51.3%.

The glucagon-like peptide-1 receptor (GLP-1 receptor) mediates important effects on peripheral tissues and the central nervous system. It seems one of the most promising therapeutic targets for treatment of diabetes mellitus type 2. Surprisingly, very little is known about the cellular mechanisms that regulate its function in vivo. One of the approaches to study receptor dynamics, expression, or signaling is using GFP-tagged fluorescent proteins. In this study, we synthesized and characterized N-terminally GFP-tagged GLP-1 (GFP-GLP-1) receptor in CHO cells. We demonstrated that GFP-GLP-1 receptor is weakly expressed in the plasma membranes and is functionally coupled to adenylyl cyclase via heterotrimeric G-proteins, similarly as its wild type.

Abstract. KRAS mutations are proved as a predictor of response to EGFR-targeted therapies for patients with metastatic colorectal cancer. For identifying the wild-type KRAS (wt-KRAS) responder subset of patients who will benefit from novel agents our laboratory has introduced the TheraSreen K-RAS Mutation Kit ® an allele-specific RT-PCR based assay. Our aim is to describe the validation procedure of this method in our laboratory, determine the portion of colorectal cancer patients with wt-KRAS status, and assess the prognostic power of mutational status for the anti-EGFR therapy outcome in colorectal cancer patients. In this study 302 samples from 273 patients with metastatic colorectal cancer were tested for 7 most common mutations on codon 12 and 13 of the KRAS gene. We used HT-29 and CCL-247 cell lines to determine the sensitivity of the method for different proportions of tumor cells in the sample. We determined that 2% of cells carrying a KRAS mutation must be present in the sample for an undisputable detection of mutated signal using the LightCycler Adapt Software. Among the tested patients 54.5% had a wt-KRAS genotype and 45.5% had a mutated KRAS genotype. The p.Gly12Asp was the most common detected mutation (38.5%). Among the cetuximab therapy responders, 85.7% had a wt-KRAS genotype. We have shown that the RT-PCR method introduced to discriminate between anti-EGFR therapy responders and non-responders is efficient, reliable and quickly applicable. The ratio of mutated versus wt-KRAS patients in our study is similar to ratios reported by other authors, as is the high correlation between wt-KRAS genotype and response to cetuximab therapy. Nevertheless the selection of patients for treatment solely on the basis of KRAS status is not perfect due to the fact that some responders are among the patients with mutated KRAS and some non-responders among the wt-KRAS patients.