Clinical Significance Of Expression Of PTEN In Human Small Cell Lung Cancer

In 1997, a new tumor suppressor gene was separated and cloned in succession by three study groups of America, which was named phosphatase and tensin homologue deleted on chromosome ten ( PTEN) , mutated in multiple advanced cancer 1 ( MMAC1) and TGF -β1 - regulated and epithelia cell - enriched phosphatase 1(TEP1) respectively. It has been generally accepted that the suppressor gene played an extremely important role in the regulation of cellular growth, development and apoptosis. It may impact the infiltration, the metastasis and the package of skeleton protein of the tumor cell, and play a significant role in the cell signaling and other biology process. According recent reports, the loss of the PTEN could occur on several different levels, such as the mutation and loss of DNA and/or deactivation of RNA and protein, which could take place in the process of development and advancement of varied tumors, and could be regulated on varied levels. However, there were few studies on the relationship between the tumor suppressor gene, PTEN, and pulmonary carcinoma, besides, whose results were relatively different. Nevertheless, majority of these studies revealed the mutation and the deactivation of the tumor suppressor gene, PTEN, could occur in pulmonary carcinoma, especially small - cell lung cancer. They believed that there were universal genie injuries in SCLC. It is extremely important for our victory in the war against SCLC to make the mechanism and clinical significance clear.In our study, we planed to study and research the express level of PTEN in SCLC, and investigate its effect in the development and the proliferation of SCLC. Furthermore, we could evaluate how it impacted the prognosis of thepostoperative patients with SCLC.Methods:62 patients in the first clinical college of CMU and their operative specimens between Jan 1997and Dec 2002 were identified, including 20 cases of non - small - cell lung cancer ( NSCLC ) and 42 cases of small - cell lung cancer (SCLC). All of the specimens were stained with S - P immunohistochemical technique. We used primary antibody to PTEN. Then we calculated the rate of positive expression of every entity. We divided all the cases of SCLC into several groups by sex, age and the different stage of T and N, according to the TNM staging system of UICC in 1997. Statistically, we compared the rate of positive expression of each group with its counterpart. Moreover, 30 postoperative patients with SCLC were followed up, and we compared their survival rate by different positive PTEN expression rate.SPSS 12.0 was used for statistical analysis. Chi - square test was used for difference between group, and Kaplan - Meier survival curve was used for survival rate comparison, Log - rank test for survival curve comparison. Significance level was P <0.05.Results;There was no significant difference between SCLC and NSCLC ( P > 0.05 ) . And the patients who had a positive PTEN expression seemed to have a better prognosis than those who had negative one (P <0. 05). In SCLC, the loss of PTEN protein was related to T stages ( P < 0. 05) , but not to sex and age of patients ( P > 0. 05) .ConclusionsThe tumor suppressor gene, PTEN, might inhibit the tumor growth and hematogenous metastasis.