[Correlation between the presence of Kras mutation and the presence of the proteins epiregulin and amphiregulin in colon cancer tissue].

INTRODUCTION: Progress has been made in the treatment of metastatic colorectal cancer with the development of biologic agents such as Cetuximab and Panitumumab. These monoclonal antibodies are directed against EGFR and influence cell division, attachment, angiogenesis, migration and apoptosis. Correlation has been found between the presence of mutations in the K-ras gene and resistance to treatment with Cetuximab.New guidelines require K-ras mutation analysis before anti-EGFR treatment is provided. The proteins Amphiregulin and Epiregulin belong to the Epidermal growth factors family (EGF, that act through the EGFR. Over-expression of these proteins has been seen in a variety of malignancies and non-malignant pathologies. These proteins can be detected in samples from colorectal malignancies and inflammatory bowel disease by immunohistochemical staining. Jacobs et at showed that mRNA expression of these proteins n colorectal malignancy predicts outcomes in wild type K-ras metastatic patients treated with Cetuximab. AIM: The purpose of our study is to examine whether there is a correlation between the presence of colorectal cancer K-ras mutations and the level of expression of EpireguLin and Amphiregulin in the malignant tissue. MATERIAL AND METHODS: In a retrospective study we examined 30 tissue samples of colon cancer patients for the presence of K-ras mutation and immunohistochemicaL staining for Epiregulin and AmphireguLin. RESULTS: A total of 14 (46.66%] samples showed mutation in the K-ras gene; 15 of 30 samples [50%] were positive for AmphireguLin. As for Epiregulin, 10 (33.3%) samples had strong staining, 10 (33.3%) samples had Light staining and the rest, 10 (33.3%) didn't have any staining. In conclusion, we did not find a correlation between the presence of a K-ras mutation and the presence of Epiregulin and Amphiregulin in colon cancer tissue.

Involvement of IGF-1R regulation by miR-515-5p modifies breast cancer risk among BRCA1 carriers.

Several lines of evidence indicate that sequence alterations within microRNA (miRNA)-binding sites can modify the binding to its target gene resulting in altered expression patterns. We hypothesized that a single nucleotide polymorphism (SNP) located in the miR-515-5p binding site of igf-1r gene may alter IGF-1R regulation, with consequent effects on breast cancer risk in BRCA1 mutation carriers. Computational prediction revealed that the rs28674628 SNP in the igf-1r 3' UTR is located within a predicted binding site for miR-515-5p. The effect of this SNP on breast cancer risk was evaluated by genotyping 115 Jewish Ashkenazi carriers of the 185delAG mutation in the BRCA1 gene using the Sequenom platform followed by Kaplan-Meier analysis. Additional data set of 378 Jewish BRCA1 carriers was analyzed to validate our results. MiRNA transfection, Western blot analysis, luciferase reporter assay, real time PCR, and immunohistochemistry were performed to assess direct regulation of igf-1r by miR-515-5p. We show direct regulation of IGF-1R by miR-515-5p. We identified that disrupting miR-515-5p and igf-1r 3' UTR binding by SNP may cause elevated IGF-1R protein levels. Interestingly, miR-515-5p is downregulated in tumor tissue compared to its non-neoplastic surrounding tissue while IGF-1R levels are elevated. This igf-1r SNP was found to be significantly associated with age at diagnosis of breast cancer in Jewish Ashkenazi BRCA1 mutation carriers. These findings support the hypothesis that a SNP located in igf-1r gene may alter miRNA regulation of IGF-1R, with a putative effect on BRCA1 penetrance and breast cancer risk.

Silencing of a large microRNA cluster on human chromosome 14q32 in melanoma: biological effects of mir-376a and mir-376c on insulin growth factor 1 receptor.

BACKGROUND: Metastatic melanoma is a devastating disease with limited therapeutic options. MicroRNAs (miRNAs) are small non coding RNA molecules with important roles in post-transcriptional gene expression regulation, whose aberrant expression has been implicated in cancer. RESULTS: We show that the expression of miRNAs from a large cluster on human chromosome 14q32 is significantly down-regulated in melanoma cell lines, benign nevi and melanoma samples relative to normal melanocytes. This miRNA cluster resides within a parentally imprinted chromosomal region known to be important in development and differentiation. In some melanoma cell lines, a chromosomal deletion or loss-of-heterozygosity was observed in the cis-acting regulatory region of this cluster. In several cell lines we were able to re-express two maternally-induced genes and several miRNAs from the cluster with a combination of de-methylating agents and histone de-acetylase inhibitors, suggesting that epigenetic modifications take part in their silencing. Stable over-expression of mir-376a and mir-376c, two miRNAs from this cluster that could be re-expressed following epigenetic manipulation, led to modest growth retardation and to a significant decrease in migration in-vitro. Bioinformatic analysis predicted that both miRNAs could potentially target the 3'UTR of IGF1R. Indeed, stable expression of mir-376a and mir-376c in melanoma cells led to a decrease in IGF1R mRNA and protein, and a luciferase reporter assay indicated that the 3'UTR of IGF1R is a target of both mir-376a and mir-376c. CONCLUSIONS: Our work is the first to show that the large miRNA cluster on chromosome 14q32 is silenced in melanoma. Our results suggest that down-regulation of mir-376a and mir-376c may contribute to IGF1R over-expression and to aberrant negative regulation of this signaling pathway in melanoma, thus promoting tumorigenesis and metastasis.

FOXL2 C402G mutation detection using MALDI-TOF-MS in DNA extracted from Israeli granulosa cell tumors.

OBJECTIVE: To develop a rapid, sensitive and reliable method to detect FOXL2 C402G mutation in granulosa cell tumor (GCT) and to investigate the prevalence of FOXL2 mutation in granulose cell tumors among Israeli patients. METHODS: We designed and optimized a matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) genotyping assay to detect FOXL2 C402G mutation in DNA isolated from formalin-fixed paraffin-embedded tissue samples. We examined 20 tumor samples obtained from Israeli patients diagnosed with granulose cell tumor. RESULTS: Eighteen out of 20 samples were found to harbor FOXL2 C402G mutation. Pathological review of the two tumors harboring wild type FOXL2 (C402) concluded that they were adenocarcinomas and has been misclassified at initial diagnosis. We found that the prevalence of FOXL2 mutations among Israeli patients with GCT (100%) is similar to previous reports. CONCLUSIONS: Our results indicate that the FOXL2 mutations can be reliably detected by MALDI-TOF-MS genotyping. MALDI-TOF-MS genotyping is a simple, robust and highly sensitive method to detect FOXL2 C402G mutation. Our results confirm previous studies reporting over 95% prevalence of FOXL2 mutation in GCT. Furthermore, we suggest that testing for the presence of the FOXL2 C402G mutation may improve diagnostic accuracy.