Hematologic Neoplasms ; genetics ; Humans ; Proto-Oncogene Proteins B-raf ; genetics

The clinical benefits of oncogenic BRAF inhibitor therapies are limited by the emergence of drug resistance. In this study, we investigated the role of a negative regulator of the MAPK pathway, Spry2, in acquired resistance using BRAF inhibitor-resistant derivatives of the BRAF-V600E melanoma (A375P/Mdr). Real-time RT-PCR analysis indicated that the expression of Spry2 was higher in A375P cells harboring the BRAF V600E mutation compared with wild-type BRAF-bearing cells (SK-MEL-2) that are resistant to BRAF inhibitors. This result suggests the ability of BRAF V600E to evade feedback suppression in cell lines with BRAF V600E mutations despite high Spry2 expression. Most interestingly, Spry2 exhibited strongly reduced expression in A375P/Mdr cells with acquired resistance to BRAF inhibitors. Furthermore, the overexpression of Spry2 partially restored sensitivity to the BRAF inhibitor PLX4720 in two BRAF inhibitor-resistant cells, indicating a positive role for Spry2 in the growth inhibition induced by BRAF inhibitors. On the other hand, long-term treatment with PLX4720 induced pERK reactivation following BRAF inhibition in A375P cells, indicating that negative feedback including Spry2 may be bypassed in BRAF mutant melanoma cells. In addition, the siRNA-mediated knockdown of Raf-1 attenuated the rebound activation of ERK stimulated by PLX4720 in A375P cells, strongly suggesting the positive role of Raf-1 kinase in ERK activation in response to BRAF inhibition. Taken together, these data suggest that RAF signaling may be released from negative feedback inhibition through interacting with Spry2, leading to ERK rebound and, consequently, the induction of acquired resistance to BRAF inhibitors.
Cell Line ; Drug Resistance ; Hand ; Melanoma ; Proto-Oncogene Proteins c-raf

Carcinoma, Papillary ; genetics ; Humans ; Mutation ; Proto-Oncogene Proteins B-raf ; genetics ; Thyroid Neoplasms ; genetics

Melanoma accounts for a small proportion of skin cancers diagnosed each year, but it has a high degree of malignancy and rapid progression, resulting in a short survival period for patients. The incidence of melanoma continues to rise, and now melanoma accounts for 1.7% of cancer diagnoses worldwide and is the fifth most common cancer in the United States. With the development of high-throughput sequencing technologies, the understanding of the pathophysiology of melanoma had also been improved. The most common activating mutations in melanoma cells are BRAF , NRAS , and KIT mutations, which disrupt cell signaling pathways related to tumor proliferation. The progress has led to the emergence of molecularly targeted drugs, which extends the survival of patients with advanced melanoma. A large number of clinical trials have been conducted to confirm that targeted therapy for patients with advanced melanoma can improve progression-free survival and overall survival, and for stage III patients after radical tumor resection targeted therapy can reduce the recurrence of melanoma. Patients who were originally stage III or IV inoperable have the opportunity to achieve tumor radical resection after targeted therapy. This article reviewed the clinical trial data and summarized the clinical benefits and limitations of these therapies.
Humans ; United States ; Melanoma/genetics* ; Skin Neoplasms/pathology* ; Mutation ; Proto-Oncogene Proteins B-raf/therapeutic use*

The development of next generation sequencing (NGS) has led to marked advancement of our understanding of genetic events mediating the initiation and progression of thyroid cancers. The NGS studies have confirmed the previously reported high frequency of mutually-exclusive oncogenic alterations affecting BRAF and RAS proto-oncogenes in all stages of thyroid cancer. Initially identified by traditional sequencing approaches, the NGS studies also confirmed the acquisition of alterations that inactivate tumor protein p53 (TP53) and activate phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) in advanced thyroid cancers. Novel alterations, such as those in telomerase reverse transcriptase (TERT) promoter and mating-type switching/sucrose non-fermenting (SWI/SNF) complex, are also likely to promote progression of the BRAF(V600E)-driven thyroid cancers. A number of genetically engineered mouse models (GEMM) of BRAF(V600E)-driven thyroid cancer have been developed to investigate thyroid tumorigenesis mediated by oncogenic BRAF and to explore the role of genetic alterations identified in the genomic analyses of advanced thyroid cancer to promote tumor progression. This review will discuss the various GEMMs that have been developed to investigate oncogenic BRAF(V600E)-driven thyroid cancers.
Animals ; Carcinogenesis ; Catalytic Domain ; Mice ; Mice, Transgenic ; Negotiating ; Proto-Oncogene Proteins B-raf ; Proto-Oncogenes ; Telomerase ; Thyroid Gland ; Thyroid Neoplasms

PURPOSE: To assess the prevalence of KRAS, BRAF, and TP53 mutations in cases of low-grade and high-grade serous carcinomas and to evaluate the clinical outcomes of these morphologically distinct carcinomas. MATERIALS AND METHODS: Patients with primary invasive serous carcinomas were classified according to the universal grading system. Grade 2 serous tumors were excluded. A total of 100 patients were included for clinical evaluation. Thirty-seven patients, including 20 with low-grade and 17 with high-grade carcinomas, were selected for mutational analysis. RESULTS: The low-grade carcinoma group was characterized by young age and premenopausal period compared with the high-grade carcinoma group, but there were no statistically significant differences in stage, metastasis of lymph node and residual disease. There were no statistically significant differences in survival rates, however, the low-grade carcinoma group showed a trend for improved progression-free survival compared with the high-grade carcinoma group of early stage (p = 0.064). Mutations in KRAS and BRAF were found in 6 (30%) and 2 (10%) patients in the low-grade carcinoma group, respectively, however, they were not found in the high-grade carcinoma group. KRAS and BRAF mutations were mutually exclusive, and both mutations were observed in 40% (8/20). The frequency of TP53 mutations in low-grade and high-grade carcinoma groups were found in 20% (4/20) and 70.6% (12/17), respectively (p = 0.009). CONCLUSION: Low-grade serous carcinoma shows mutation pattern different from that with high-grade carcinoma. As there were no significant differences in stage distribution and survival, especially in advanced stage, we suggest that more studies are needed to segregate these patients into distinct disease entities.
Adult ; Cystadenocarcinoma, Serous/*genetics ; DNA Mutational Analysis ; Female ; Humans ; Middle Aged ; Ovarian Neoplasms/*genetics ; Proto-Oncogene Proteins/*genetics ; Proto-Oncogene Proteins B-raf/*genetics ; ras Proteins/*genetics

Colorectal Neoplasms ; genetics ; DNA Mutational Analysis ; standards ; Humans ; Mutation ; Proto-Oncogene Proteins B-raf ; genetics ; ras Proteins ; genetics

OBJECTIVETo investigate mutations frequencies of KRAS,NRAS and BRAF genes in colorectal carcinoma.

METHODSTissue specimens from 200 colorectal cancer patients at diagnosis were collected and subject to KRAS,NRAS and BRAF mutation analyses by PCR-based direct DNA sequencing targeting exons 2, 3 and 4 of KRAS gene, exons 2, 3 and 4 of NRAS gene and exon 15 of BRAF gene.

RESULTSActivating mutations were detected in KRAS (44%, 88/200), NRAS (2%, 4/200) and BRAF (5%, 10/200) in this study cohort.Among KRAS mutations, 64.8% (57/88) occurred in codon 12 and 12.5% (11/88) occurred in codon 13. KRAS gene mutation in exon 3 mainly involved codons 59 and 61. KRAS gene mutation in exon 4 mainly involved codons 117 and 146.

CONCLUSIONSMutations at exon 2 of KRAS gene have the highest frequency in colorectal carcinoma. Expanding the detection sites of KRAS gene combined with NRAS and BRAF genes may help to identify patients who will most likely benefit from targeted therapies.

Base Sequence ; Codon ; Colorectal Neoplasms ; genetics ; DNA Mutational Analysis ; Exons ; Female ; Genes, ras ; Humans ; Mutation ; Proto-Oncogene Proteins ; Proto-Oncogene Proteins B-raf ; genetics ; Sequence Analysis, DNA

Humans ; Proto-Oncogene Proteins p21(ras)/genetics* ; Prognosis ; Biomarkers, Tumor/genetics* ; Mutation/genetics* ; Colorectal Neoplasms/genetics* ; Proto-Oncogene Proteins B-raf/metabolism*

Antineoplastic Agents ; therapeutic use ; Colorectal Neoplasms ; classification ; drug therapy ; genetics ; pathology ; Humans ; Microsatellite Instability ; Mutation ; Polymorphism, Single Nucleotide ; Precision Medicine ; Proto-Oncogene Proteins ; genetics ; Proto-Oncogene Proteins B-raf ; genetics ; Proto-Oncogene Proteins p21(ras) ; ras Proteins ; genetics