RESUMO
BACKGROUND/AIMS: Non-small cell lung cancer (NSCLC) is one of the deadliest cancers worldwide. Dopamine receptor D2 (DRD2) has multiple roles in clinical progression of NSCLC and functional maintenance of cancer cells. However, little is known about the molecular mechanism. Here, we clarified whether DRD2 inhibits lung cancer progression and identified the underlying downstream signaling. METHODS: DRD2 mRNA and protein levels were detected in clinical specimens by qRT-PCR and immunohistochemistry, respectively. MTT and colony formation assays were applied to analyze cell proliferation. The underlying molecular mechanism was identified by dual luciferase, western blot, qRT-PCR, cAMP detection, immunoprecipitation, and chromatin immunoprecipitation assays. A murine NSCLC model was used to clarify the role of DRD2 in tumor cell proliferation. RESULTS: We found that DRD2 ablated tumor cell growth. DRD2 expression in NSCLC tissues was lower than in adjacent normal lung tissues. Moreover, DRD2 mRNA and protein levels in NSCLC were negatively correlated with the tumor size, TNM status, and patient overall survival. In vitro experiments showed that disruption of DRD2 promoted the proliferation of NSCLC cell lines A549 and SK-MES-1 by inhibiting the NF-κB signaling pathway. Furthermore, DRD2 overexpression not only blocked lipopolysaccharide-induced A549 and SK-MES-1 cell proliferation and growth, but also inhibited the tumorigenesis in murine xenograft models. CONCLUSION: These results indicate that DRD2 may be a potential therapeutic target for lung cancer patients with high DRD2 expression by ablating the NF-κB signaling pathway.
Assuntos
Carcinoma Pulmonar de Células não Pequenas/patologia , Neoplasias Pulmonares/patologia , Receptores de Dopamina D2/metabolismo , Animais , Carcinoma Pulmonar de Células não Pequenas/mortalidade , Linhagem Celular Tumoral , Proliferação de Células , Feminino , Humanos , Estimativa de Kaplan-Meier , Masculino , Camundongos , Camundongos Nus , Pessoa de Meia-Idade , NF-kappa B/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/genética , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Interferência de RNA , RNA Interferente Pequeno/metabolismo , Receptores de Dopamina D2/química , Receptores de Dopamina D2/genética , Transdução de Sinais , Fator de Transcrição RelA/genética , Fator de Transcrição RelA/metabolismo , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Human Cripto-1 (CR-1) plays an important oncogenic role during tumorigenesis and is overexpressed in a wide range of carcinomas, yet little is known about CR-1 in non-small cell lung cancer (NSCLC). The aims of this study were to detect CR-1 expression in NSCLC and to analyze its association with prognosis of NSCLC patients. The expression of CR-1 messenger RNA (mRNA) and protein in 35 cases of NSCLC and corresponding noncancerous tissue samples was examined by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) and Western blotting. Immunohistochemistry was performed to detect the expression of CR-1 in 128 NSCLC tissues. The expression levels of CR-1 mRNA and protein in NSCLC tissues were significantly higher than those in corresponding noncancerous tissues (P < 0.001). A high level of CR-1 expression was correlated with poor tumor differentiation (P = 0.002), tumor-node-metastasis (TNM) stage (P = 0.004), and lymph node metastasis (P = 0.001). The results of the Kaplan-Meier analysis indicated that a high expression level of CR-1 resulted in a significantly poor prognosis of NSCLC patients. Multivariate Cox regression analysis revealed that CR-1 expression level was an independent prognostic parameter for the overall survival rate of NSCLC patients. Our data suggest that the high expression of CR-1 may play an important role in the progression of NSCLC, and CR-1 expression may offer a valuable marker for predicting the outcome of patients with NSCLC.
