Abstract: Background and purpose: Prospero-related homeobox protein 1 (PROX1) is a highly conserved transcription regulator, which is involved in the occurrence and development of many types of tumors. The purpose of this study was to investigate the expression of PROX1 and its significance in non-small cell lung cancer (NSCLC). Methods: Immunohistochemical method was used to detect the expression of PROX1 in 86 NSCLC cancer tissues and their matched adjacent tissues from Jan. 2011 to Jun. 2013 in the Zibo First Hospital. The expression of PROX1 in human NSCLC cell lines A549, H460, H1229, H358 and human bronchial epithelial cells Beas-2b was detected by Western blot. Kaplan-Meier method was used for survival analysis, and COX proportional risk regression model was used to analyze the influencing factors of survival prognosis in NSCLC patients. Results: There were 6 PROX1 negative, 25 weak positive, 20 medium positive and 35 strong positive cases in cancer tissues, whereas there were 48 PROX1 negative, 27 weak positive, 8 medium positive and 3 strong positive cases in para-cancerous tissues, respectively. The positive expression rate of PROX1 in cancer tissues was significantly higher than that in para-cancerous tissues (P<0.05). Compared with Beas-2b, the expression of PROX1 protein in A549, H460, H1229 and H358 cells was significantly higher (P<0.05). The proportion of lymph node metastasis and TNM stage Ⅲ-Ⅳ in PROX1 high expression group was significantly higher than that in low expression group (P<0.05). TNM stage Ⅲ-Ⅳ , lymph node metastasis, distant metastasis and high expression of PROX1 were independent influencing factors of poor survival and prognosis in NSCLC (P<0.05). The survival time of PROX1 high expression group was significantly lower than that of low expression group (P<0.05). After knockdown of PROX1, PROX1 protein expression levels, the clone number of A549 cells, the D value of cell proliferation and the number of invasion and migration cells decreased significantly (P<0.05). Conclusion: PROX1 may play an important role in the occurrence and development of NSCLC. Knockdown of PROX1 gene could inhibit the proliferation, invasion and migration of NSCLC cells. High PROX1 expression might predict the poor prognosis of patients.

Key words: Prospero-related homeobox protein 1, Non-small cell lung cancer, Proliferation, Invasion, Migration