| Background and Objection:Breast cancer is one of the most common cancers among women. In2008, there are about1380,000people suffering from breast cancer, accounting for about22.9%of malignant tumors of the female every year. In the European and American countries, breast cancer accounts for25%-30%of the female malignant tumor. Compared with western countries, China has lower incidence of breast cancer. However, with the development of industry and the change of lifestyle, the incidence among Chinese women is increasing. In China, new cases of breast cancer in2008(169,000) increased by34%compared with that in2002, seriously endangering women’s health. Breast cancer has become one of the key programs for cancer prevention in China.In the last20years, the treatment of breast cancer has evolved very rapidly and become increasingly complex. Systematic treatment consists of surgery, chemotherapy, endocrine therapy, radiotherapy, and molecular-targeted therapy and requires a comprehensive assessment and review of multiple issues. Some novel biological targeted agents have been developed in recent years, resulting in great advances in breast cancer treatment. Many scientists make efforts to explore the functions and characteristics of oncogenes. Genetic mutations may lead to abnormal activation of oncogenes, which increasing the risk of the transformation of normal cells to tumor cells. Recent research shows that there is at least one cancer gene mutation in30%of cancers. The more the cognition of the gene mutations, the fast we break through the bottleneck for the treatment of malignant tumors. Accomplishing such a task requires a lot of information of the featrure of cancer genes, and the accumulation of these information can be converted into strong evidence of molecular-targeted therapy.The epidermal growth factor receptor (EGFR) is one potential therapeutic target. It encodes a transmembrane glycoprotein, a member of the protein kinase superfamily, which is a receptor for members of the epidermal growth factor family and is involved in the survival and proliferation of cancer cells. EGFR tyrosine kinase inhibitors are thought to inhibit activated EGFR, blocking one of the key drivers of the disease and consequently improving patient outcomes. EGFR inhibitors include Lapatinib, Gefitinib and Erlotinib, which have been investigated in non-small cell lung cancer (NSCLC) and colorectal cancer.Mutations that lead to EGFR overexpression or overactivity have been associated with lung, breast, colon, and pancreatic cancers. Compared with NSCLC and colorectal cancer, however, anti-EGFR targeted therapy does not produce a dramatic clinical response in breast cancer. Studies of the response of NSCLC to anti-EGFR therapy indicate that the presence of EGFR mutations is a better indicator of a response to specific EGFR inhibitors than is EGFR expression. Furthermore, few studies have reported on EGFR expression in breast cancer. Therefore, evaluation of the presence of EGFR mutations in breast cancer is critical.In addition to factors of EGFR itself, the key genes in the pathway of EGFR in the treatment of breast cancer were also concerned. The PIK3CA/Akt and RAS/RAF/MEK pathways are two major signalling cascades downstream of EGFR that participate in many pathological and physiological processes, including cell proliferation, migration, and resistance to apoptosis, angiogenesis, and tumour cell invasion. The clinical responses of patients differ according to the genetic variant of the drug target. Downstream drug-resistant genes and PIK3CA, KRAS, and BRAF mutations are now part of the Quest Diagnostics Colorectal Cancer Mutation Panel. Quest reports that testing for mutations in both BRAF and KRAS, two key genes in EGFR downstream signalling pathways, increases the ability to predict sensitivity or resistance to colon cancer drugs. However, current guidelines for the treatment of breast cancer do not include testing for these mutations. Therefore, evaluation of not only EGFR mutations, but also mutations of the downstream signalling pathway genes, is necessary to determine the mechanism of drug action.A large number of studies have reported that breast cancers in different populations have a different development process. In the background that the prevalence of breast cancer is falling all around the world, the incidence of breast cancer in China is increasing inversely, which explains that compared with Caucasians, breast cancer in Oriental populations is a heterogeneous disease with divergent molecular mechanisms of pathogenesis. Most of the description and analysis of the clinical pathological characteristics of breast cancer is based on the data of western women, so descriptions of the pathological characteristics of breast cancer in Asia are not enough. Furthermore, at present, there are a small number of researches discussing genetic mutations in Breast cancer in Caucasians, which are not fully applicable for Chinese patients. In this research, we described and analyzed the clinical pathological characteristics of breast cancer in Guangdong China and investigated mutations in key genes of EGFR pathways using a high accuracy and sensitivity gene mutation-profiling platform to increase understanding of breast cancer in China.After the investigation of mutations in key genes in EGFR pathways in breast cancer patients, this study detected238important gain-of-function candidate mutations of19oncogenes in10kinds of breast cancer cell lines, which aimed to provide basis for experiments about targeted drugs through screening key genes mutations.Methods:1.120cases with breast carcinoma randomly selected from those with complete clinical and pathological data and frozen pathology tissues were analyzed from May2011to May2012to summarize clinical and pathological features and to analysis the link between the indicators accomplished with SPSS13.0software.2. The Sequenom MassARRAY(?)-IPLEX platform was used for mutation detection. The genes investigated (AKT1, BRAF, EGFR, HRAS, KRAS, NRAS and PIK3CA) play important roles in the PIK3CA/Akt and RAS/RAF/MEK pathways, two major signalling cascades downstream of EGFR. Based on their relevance,22candidate mutations were selected (Table1). These do not usually occur randomly, but are more frequent in certain genomic regions and affect gene function, which is important in the natural selection process that takes place during tumorigenesis or once an individual undergoes treatment. Mutations were picked out from the NCBI SNP database and primers were design through primer design software (Sequenom Assay Designer4.1). Mutations were detected following the manufacturer’s protocol (Sequenom; San Diego, CA, USA)。 Mutations were identified automatically and manually.3. This study detected238candidate mutations of19genes in10kinds of breast cancer cell lines using Sequenom OncoCartaTM Assay Panel v1.0through Sequenom MassARRAY(?)-IPLEX platform. These19genes are oncogenes and the mutations were all gain-of-function point mutations.Conclusion1. In this study, the age, tumour type, disease stage, mass size, histological grading, axillary lymph node metastasis status,ER,PR,HER-2,KI-67status of the120breast cancer patients were statistical analyised. This study found that the expression of ER and/or PR is negatively related(P<0.05)with the expression of HER-2and the expression of KI67and histological grading are statistically related (P<0.05), however no other relationships analyzed is statistically significant.2. In the detection of mutations in120breast cancers, thirteen mutations were identified in12(10%) of the samples, consisted of2,6,4at stages I to III, respectively.3(50%) genes (EGFR, KRAS and PIK3CA) were found to mutated in the cases. Of the22genotyping assays used here, six (27.27%) called a mutation in at least one sample, and three (50%) of the six queried were mutated more than once. One sample had one KRAS and one PIK3CA mutation.3.18mutations of8genes(ABL1, KIT, EGFR, HRAS, KRAS, NRAS, PDGFRA and PIK3CA)were detected in the10kinds of breast cancer cell lines and each of the cell lines have at least one mutation. |
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