Proliferating cell nuclear antigen (
PCNA) functions as a bridging molecule, which targets
proteins that have distinct roles in cell growth. The expression of
PCNA is dysregulated in some
tumors and takes part in the progression of
oncogenesis. However, the roles of
PCNA in the progression of
non-small cell lung cancer (NSCLC) remain unknown. The present study aimed to investigate the function of
PCNA in the occurrence and development of NSCLC and its underlying molecular mechanisms. Western blotting, RT-PCR, and immunohistochemistry assays were used to detect the expression pattern of
PCNA in NSCLC tissues and cells. A log rank test was performed to compare the overall survival (OS) of patients with high/low expression of
PCNA. Besides, the relationship between
PCNA and signal transducer and activator of transcription-3 (STAT3)
proteins were evaluated. Then, MTT, flow cytometry, clonal formation, and in vivo xenograft assays were conducted to investigate the effects of
PCNA/STAT3 on cell growth, clonal formation, apoptosis, and
tumorigenesis. Results showed that
PCNA expression was elevated in NSCLC tissues and cells and it could combine with STAT3 and increased its expression and phosphorylation. Moreover, the expression of
PCNA showed a positive correlation with the TNM grade and occurrence rate of the
lymphatic metastasis and poor prognosis of NSCLC patients. Overexpression of
PCNA promoted cell proliferation, clonal formation, and
tumorigenesis in
lung cancer cells and inhibited cell apoptosis. In contrast, these effects were inhibited when knockdown of STAT3. In conclusion, this study demonstrates that
PCNA functions as an oncogene in the progression of NSCLC through up-regulation of STAT3. These findings point to a potentially new therapeutic strategy for NSCLC.