Cullin 4A (Cul4A) reportedly has oncogenic roles in several cancer types by regulating tumor suppressors through the ubiquitination and proteolysis of the tumor suppressor. In addition, Cul4A is associated with chemosensitivity to chemotherapy drugs. This study investigated the association between Cul4A and lung cancer cell chemosensitivity to paclitaxel, particularly with respect to the role of the p33 inhibitor of the growth 1 (p33ING1b) tumor suppressor. The results showed that the Cul4A knockdown upregulated the p33ING1b expression in lung cancer cells and increased the lung cancer cell and mice tumor xenograft chemosensitivity to paclitaxel. The Cul4A knockdown also inhibited the growth and increased the apoptosis in the tumor xenografts treated with paclitaxel. Notably, the p33ING1b overexpression increased the lung cancer cell chemosensitivity to paclitaxel, but the p33ING1b knockdown reduced the chemosensitivity. A further analysis demonstrated that Cul4A regulates the expression of p33ING1b through protein-protein interactions, ubiquitination, and protein degradation. In conclusion, the present findings suggest that Cul4A mediates the chemosensitivity of lung cancer cells to paclitaxel by regulating p33ING1b. These findings may offer novel insights into future therapeutic strategies for lung cancer that target Cul4A.

: Cullin 4A (Cul4A) is overexpressed in a number of cancers and has been established as an oncogene. This study aimed to elucidate the role of Cul4A in lung cancer invasion and metastasis. We observed that Cul4A was overexpressed in non-small cell lung cancer (NSCLC) tissues and the overexpression of Cul4A was associated with poor prognosis after surgical resection and it also decreased the expression of the tumor suppressor protein annexin A10 (ANXA10). The knockdown of Cul4A was associated with the upregulation of ANXA10, and the forced expression of Cul4A was associated with the downregulation of ANXA10 in lung cancer cells. Further studies showed that the knockdown of Cul4A inhibited the invasion and metastasis of lung cancer cells, which was reversed by the further knockdown of ANXA10. In addition, the knockdown of Cul4A inhibited lung tumor metastasis in mouse tail vein injection xenograft models. Notably, Cul4A regulated the degradation of ANXA10 through its interaction with ANXA10 and ubiquitination in lung cancer cells. Our findings suggest that Cul4A is a prognostic marker in NSCLC patients, and Cul4A plays important roles in lung cancer invasion and metastasis through the regulation of the ANXA10 tumor suppressor.