CITED4 enhances the metastatic potential of lung adenocarcinoma.

BACKGROUND: CITED4 belongs to the CBP/p300-interacting transactivator with glutamic acid and aspartic acid-rich tail (CITED) family which is induced by various cytokines and participates in cytokine-induced proliferation and differentiation. CITED4 is induced by HB-EGF in lung cancer cells. However, it is unclear whether and how CITED4 contributes to the invasion and metastasis of lung adenocarcinoma (ADC). METHODS: CITED4 expression in lung adenocarcinoma and its association with disease-free survival (DFS) and overall survival were analyzed based on a cohort of 261 patients. The roles of CITED4 were validated via loss-of-function and gain-of-function experiments. The relationship between CITED4 and CLDN3 was validated by immunohistochemistry, Western blotting, and luciferase reporter assays. The function of the CITED4-CTNNB1-CLDN3 complex was fully validated and described. RESULTS: CITED4 expression was significantly upregulated in ADC tissues and cells and a predictor for DFS. Downregulation of CITED4 attenuated the proliferation and invasion, whereas CITED4 overexpression enhanced these effects. Overexpression and knockdown of CITED4 resulted in the upregulation and downregulation of CLDN3, respectively. Moreover, CITED4 downregulation suppressed CLDN3-mediated ADC cell metastasis in vivo. CITED4 was highly expressed and positively correlated with CLDN3. Mechanistically, CITED4 interacted with CTNNB1 and functioned synergistically to enhance CLDN3 transcription. Importantly, CITED4 induced ADC invasion via a CLDN3-dependent pathway. CITED4 determined the level of CLDN3, which in turn affected the sensitivity of tumors to Clostridium perfringens enterotoxin treatment. CONCLUSIONS: The CITED4-CTNNB1-CLDN3 axis plays a key role in the invasion and metastasis of ADC and provides a novel therapeutic target for lung cancer treatment.