Yuanyuan Niu¹, Huijuan Wang¹, Zhiyong Ma¹, Jie Ma², Guowei Zhang¹, Mina Zhang¹ 

¹Medical department, Henan tumor hospital/The Affiliated Cancer Hospital of Zhengzhou University, ²Pathology department, Henan tumor hospital/The Affiliated Cancer Hospital of Zhengzhou University

Objective:KRAS mutation was a poor prognostic factor in NSCLC, the patients with KRAS-MT has shorter survival than those of KRAS-WT. So it is urgentto further investigate the role of KRAS pathway and develop treatment programs for NSCLC with KRAS mutations. Long non-coding RNAs (LncRNAs) have a role in the occurrence and development of cancer, which has gained widespread attentionin recent years. Studties found that the level of LncRNAs SCAND2 expression was lower in NSCLC cells with KRAS mutation, which indicated that SCAND2 may be associated with the development of lung cancer. Therefore, this paper aims to investigate the relationship between SCAND2 and KRAS and the clinical significance of SCAND2 in NSCLC. Method: We collected the Samples of NSCLC tissues and the adjacent normal tissues from The Affiliated Cancer Hospital of Zhengzhou University. All NSCLC patients had performed surgery. The samples was freezed in liquidnitrogen immediately and then stored at -80℃. Total RNA and DNA were extracted to detect KRAS mutations. Then the expression differences of SCAND2 between tumor tissues and corresponding normal tissues as well as KRAS-WT and KRAS-MT were detected by real-time quantitative PCR method. Constructing KRAS-WT plasmidand three KRAS-MT plasmid (G12D, G12C, G12V), then over expressing the appropriate plasmid at HEK293, H1299 and A549 cells. Using Western-Blot and RT-qPCR to detect the KRAS and SCAND2. Meanwhile designed shRNA for packaging lentiviral to knockout KRAS gene, then infecting HEK293, H1299 and A549 cells. RT-qPCR was used to detect the expression of KRAS and SCAND2. The SPSS 17.0 software was used to analysis the data, α=0.05 as the level of inspection. Result: Compared with the corresponding normal lung tissues, the expression level of SCAND2 was significantly lower in most tumor tissues (t=6.096, P<0.001), as well as significantly lower in KRAS-MT tissues than the corresponding KRAS-WT tissues (t=5.035, P=0.004). The SCAND2 expression level decreased after over expressing of KRAS; while SCAND2 expression level upregulated when knock out KRAS gene. The expression level of SCAND2 in NSCLC was correlated with smoking history, cell differentiation degree, histological type and postoperative metastasis (P<0.05); but had no-relationship with gender, age, tumor size and TNM stage (P>0.05). The overall survival was significantly shorter in group with SCAND2 low expression group by Kaplan-Meier univariate; Cox multivariate regression analysis showed that SCAND2 expression level and smoking history, postoperative metastasis, histological type, cell differentiation degree were independent factors affecting the prognosis of NSCLC patients. Conclusion: SCAND2 is closely associated with the development of NSCLC, especially related to the KRAS pathway. KRAS can regulate the expression of SCAND2, so they may have a negative feedback regulation. The low expression level of SCAND2 in lung tissues is correlated with cell differentiation degree and postoperative metastasis, so SCAND2 may be involved in cells differentiation and metastasis of NSCLC. The low expression level of SCAND2 predicts poorprognosis, which is an independent risk factor for NSCLC, and SCAND2 may beused as prognostic molecular marker for NSCLC.

Key Words: lung cancer  LncRNAss  SCAND2