Smoking Impact On The Expression And Localization Of Rhoe And Rhoe In Non-small Cell Lung Cancer Prognosis Value

RhoE, a small G protein, can regulate actin cytoskeleton reorganization, leadingto the appearance of aggregates of actin filaments. Although emerging evidencesuggests that RhoE is causally involved in cancer formation and progression, little isknown about its significance in solid cancer, including lung cancer. In the presentstudy, the expression of RhoE was analyzed using Reverse Transcriptase-PolymeraseChain Reaction (RT-PCR), real-time RT-PCR, immunohistochemistry and westernblot in patients with Non-Small Cell Lung Cancer (NSCLC). Then the correlation ofRhoE overexpression with clinical parameters was evaluated. Furthermore, thepossible reasons contributing to the RhoE expression were examined by real-timegenomic PCR and mutation analysis on DNA sequence and cDNA sequence. Finally,the expression and localization of RhoE was detected in the lung cancer cell lines andthe animal models which were stimulated using tobacco smoke. Our results revealedthat RhoE expression was dramatically increased in lung cancer tissues comparedwith adjacent non-tumoral lung tissues. Immunohistochemistry showed a strongcytoplasmic staining in cancer cells compared with positive membrane staining inadjacent non-tumoral proliferative alveolar epitheliums. Moreover, the overexpressionof RhoE was significantly associated with the patients' smoking history and can serveas an independent prognostic factor. 72% tumor tissues displayed DNA copy numberchanges based on the DNA levels in the matched adjacent non-tumoral lung tissuesand this copy number changes correlated significantly with RhoE expression andsmoking history. Polymorphisms were identified but no correlation was found withthe clinicopathological features. RhoE expression was time-dependent anddose-dependent after the lung cancer cells were stimulated using tobacco smokecondensate (CSE). RhoE mRNA and protein accumulated with the time and theconcerntration of CSE and achieved the highest levels when the CSE concentrationwas 81.25ug/ml and the stimulation duration was nine hours. Meantime, we foundthat the RhoE protein focused on the periphery of the cells. The similar effect wasalso noticed in the animal model stimulated with tobacco smoke. The expression of RhoE in the nucleus and membrane increased with the elongation of stimulation, butthe level of RhoE in the cytoplasm didn't change. RhoE expression in the nucleus ofbronchial epithelia was also upregulated after long stimulation. After cessation ofstimulation, the expression of RhoE in nucleus was decreased dramatically whereasthe expression on the membrane of alveolar cells increased. The expression of RhoEin the nucleus was also downregulated in bronchial epitxhelia. To our knowledge, thisis the first report demonstrating that RhoE expression was altered when stimulated bytobacco smoke, suggesting that RhoE may be involved in the signal pathway oftobacoo metabolisms.