The Expression Of SHP-2 In Cancer Tissue At MRNA Level

Reversible protein phosphorylation is a ubiquitous mechanism for the control of signal transduction networks that regulate diverse biological processes including cell development, proliferation, differentiation and apoptosis. For the key discovery of reversible protein phosphorylation, Fischer and Krebs were awarded the Nobel Prize for Physiology or Medicine in 1992. The phosphorylation state of a protein is controlled dynamically by both protein kinases and phosphatases. Protein tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs), important part of protein kinases and phosphatases play a crucial role in normal cell development, and dysfunction of these enzymes has been implicated in human cancers, therefore,studying on PTPs became more and more important.SHP-2 is a member of protein tyrosine phosphatases (PTPase) family. Large amount of researches show that SHP-2 is correlated with various biological processes, such as cell proliferation, differentiation, migration, apoptosis and so on. SHP-2 has two important domains, one is Src homology 2 (SH2) in its N-terminal, the other is catalytical domain in its C-terminal. It is widely expressed in cytoplasm with no catalysis, when combining with its substrate on membrane, it could be stimulated. SHP-2 is highly expressed in various nonhematopoietic cells and has important pathological implications. Activation mutation of SHP-2 causes Noonan syndrome. This gain-of-function mutation of SHP-2 is also associated with sporadic juvenile myelomonocytic leukemias (JMML), myelodysplasic syndrome(MS), acute lymphoblastic leukemia(ALL), and acute myelogenous leukemia(AML).Although the role of SHP-2 in the signal pathways and its target downstreams are still unclear, it has been reported that SHP-2 could influence FAK activity, celladhesion and motility. Several studies point to SHP-2 being either a positive or a negative regulator of celladhesion and motility. It has also been reported that SHP-2 is a positive regulator in SHP-1 related pathways. Knockdown of SHP-2 caused significant reduction in the activation of ERK1/2 but not Akt. The data revealed that SHP-2 has a positive role in epidermal growth factor-induced ERK1/2 activation that it acts cooperatively rather than antagonistically. Furthermore, SHP-1, SHP-2, and Gab1 formed a signaling complex, and SHP-1 and SHP-2 interact with each other. The interaction of SHP-1 with Gab1 is mediated by SHP-2 because it was abrogated by knockdown of SHP-2, and SHP-2, but not SHP-1, binds directly to tyrosine-phosphorylated Gab1.The research has also been done that SHP-2 has higher rate of mutation in gastric carcinomas, and meanwhile has some kind of mutation in colon and desmocytoma carcinomas. It is maybe because the mutation of SHP-2 activates Ras-Erk pathways, and the pathway would not be easily influenced by other mutations, so that, the mutation of SHP-2 is a onco-genic mutation.To identify the mechanism of SHP-2, we have to determine its expression in the carcinomas and in the nomal tissues. We collect totally 159 tissues of gastric carcinoma, lung cancer, rectal cancer, ovarian cancer, esophageal cancer, uterine cervix cancer, gland cancer, colon carcinoma, carcinoma of bladder and endometrium carcinomas and also some normal tissues. We determined the mRNA level of SHP-2 in carcinomas.We find that SHP-2 is expressed in various normal tissues and carcinomas, and nearly has no difference between them, but pseudo gene in gastric carcinoma, ovarian cancer, uterine cervix cancer, gland cancer, colon carcinoma, but not in lung cancer and esophageal cancer. ,we extract total RNA from cancer and normal tissues by useing Trizol,and transcribe mRNA to cDNA,then amplify SHP-2 by Nested PCR.We divide the samples into different group accoding to their position,and detect the products by electrophoresis ,and sequencing the products.But we find no conspicuous difference between cancer and normal tissue ,but pseudo gene.