Coiled-coil domain containing (CCDC) family members enhance tumor cell proliferation, and high CCDC protein levels correlate with unfavorable prognoses. Limited research demonstrated that CCDC106 may promote the degradation of p53/TP53 protein and inhibit its transactivity. The present study demonstrated that CCDC106 expression correlates with advanced TNM stage (P = 0.008), positive regional lymph node metastasis (P < 0.001), and poor overall survival (P < 0.001) in 183 non-small cell lung cancer cases. A549 and H1299 cells were selected as representative of CCDC106-low and CCDC106-high expressing cell lines, respectively. CCDC106 overexpression promoted A549 cell proliferation and xenograft tumor growth in nude mice, while siRNA-mediated CCDC106 knockdown inhibited H1299 cell proliferation. CCDC106 promoted AKT phosphorylation and upregulated the cell cycle-regulating proteins Cyclin A2 and Cyclin B1. Cell proliferation promoted by CCDC106 via Cyclin A2 and Cyclin B1 was rescued by treatment with the AKT inhibitor, LY294002. Our studies revealed that CCDC106 is associated with non-small cell lung cancer progression and unfavorable prognosis. CCDC106 enhanced Cyclin A2 and Cyclin B1 expression and promoted A549 and H1299 cell proliferation, which depended on AKT signaling. These results suggest that CCDC106 may be a novel target for lung cancer treatment.

Lasp1 (LIM and SH3 domain protein 1) promotes tumor proliferation and invasion in multiple cancer entities including non-small cell lung cancer (NSCLC). However, the molecular mechanism is uncertain to date. In the present study, using immunohistochemistry, we found that Lasp1 expression was significantly correlated with tumor size (P=0.005), advanced TNM stage (P=0.042), positive regional lymph node metastasis (P=0.034) and poor overall survival (P<0.001). Similar results were seen in patients with squamous cell lung carcinoma (P=0.003 for larger tumor size, P=0.017 for advanced TNM stage, P=0.003 for positive lymph node metastasis and P<0.001 for poor overall survival) but not in patients with lung adenocarcinoma (P>0.05). Proliferation and invasion assay showed that Lasp1 dramatically promoted the ability of proliferation and invasion of NSCLC cells. Subsequent western blot results revealed that Lasp1 promoted the expression of Cyclin A2, CyclinB1, and Snail, and inhibited the expression of E-cadherin. Lasp1 directly interacted with FAK and facilitated the expression of phosphorylated FAK (Tyr397) and AKT (Ser473). Incorporation of both FAK inhibitor and AKT inhibitor counteracted the upregulating expression of Cyclin A2, CyclinB1, and Snail, and downregulating expression of E-cadherin expression induced by Lasp1 overexpression. Interestingly, inhibition of FAK signaling pathway attenuated the phosphorylation of AKT, but inhibition of AKT signaling pathway did not affect the phosphorylation of FAK. In conclusion, Lasp1 facilitated tumor proliferation and invasion of NSCLC through directly binding to FAK and enhancing the phosphorylation of FAK (Tyr397) and AKT (Ser473). Lasp1 may be a novel therapeutic target in the treatment of NSCLC patients.

TIMM50 (Translocase of the inner mitochondrial membrane 50), also called TIM50, plays an essential role in mitochondrial membrane transportation. The existing literature suggests that TIMM50 may perform as an oncogenetic protein in breast cancer. However, the molecular mechanism, especially in human non‐small cell lung cancer (NSCLC), is uncertain to date. In the present study, using immunohistochemistry, we found that TIMM50 expression significantly correlated with larger tumor size (P = 0.049), advanced TNM stage (P = 0.001), positive regional lymph node metastasis (P = 0.007), and poor overall survival (P = 0.001). Proliferation and invasion assay showed that TIMM50 dramatically promoted the ability of proliferation and invasion of NSCLC cells. Subsequent Western blotting results revealed that TIMM50 enhanced the expression of Cyclin D1 and Snail, and inhibited the expression of E‐cadherin. Moreover, TIMM50 facilitated the expression of phosphorylated ERK and P90RSK. Incorporation of ERK inhibitor counteracted the upregulating expression of CyclinD1, and Snail, and downregulating expression of E‐cadherin expression induced by TIMM50 overexpression. In conclusion, our data indicated that TIMM50 facilitated tumor proliferation and invasion of NSCLC through enhancing phosphorylation of its downstream ERK/P90RSK signaling pathway. We speculated that TIMM50 might be a useful prognosis marker of NSCLC patients.

Transmembrane protein 17(TMEM17) is a newly identified protein, its expression pattern and clinicopathological relevance is still unclear. In this study, western blot assay was performed in 20 paired lung cancer samples and found that TMEM17 protein levels were lower in lung cancer tissues than that in the corresponding normal lung tissues (p=0.010). Immunohistochemistry staining in 143 cases lung cancer specimens also showed that TMEM17 expression in lung cancer tissues were significantly lower than adjacent normal lung tissues (35.7% vs 63.2%, p<0.001). And negative TMEM17 expression was significantly associated with poor histological differentiation (p=0.027), advanced TNM stages (p=0.006), positive lymph node metastasis (p=0.002) and poor prognosis (p=0.002). After overexpressing TMEM17, levels of p-ERK and its downstream molecules, p-P90RSK and Snail, were down-regulated, while levels of Occludin and Zo-1 were up-regulated, which result in the inhibition of invasion and migration ability of lung cancer cells. The effects were reversed by the incorporation of specific ERK inhibitor PD98059. In conclusion, loss of TMEM17 correlates with the development of non-small cell lung cancer (NSCLC) and predicts adverse clinical outcome of NSCLC patients. The effect of TMEM17 on inhibiting invasion and migration may attribute to restoring Occludin and Zo-1 expression through inactivating ERK-P90RSK-Snail pathway.