TP53 mutations upregulate RCP expression via Sp1/3 to drive lung cancer progression.

Mutant p53 (mtp53) can exert cancer-promoting activities via "gain-of-function", which has become a popular research target. Although lots of researchers focus on the tumor-suppressor role for p53, the regulation of mutant p53 remains unknown. Here, we report a mechanism by which mtp53 regulate the transcription of Rab coupling protein (RCP) to influence lung cancer behavior. First, we show that RCP is specifically expressed at high levels in lung cancer tissues and cells, and RCP knockout suppresses tumor growth and metastasis. Further mass spectrometry and functional analysis identify that Sp1, Sp3 and Stat3 are the transcriptional activators of RCP. Moreover, p53 is involved in modulating RCP expression in an Sp1/3 dependent manner. Mechanistically, in contrast to wild-type p53 suppression of RCP transcription by decreasing Sp1/3 proteins, TP53 mutations have changed on Sp1/3 expression via "loss-of-function". Surprisingly, the DNA contact mutants of p53 further robustly enhance their binding ability with Sp1/3 to drive RCP expression through the "gain-of-function" activity. Collectively, we reveal a mechanism by which p53 regulating the transcription of RCP to influence lung cancer progression, which provides new insights for treating p53 mutant lung cancer.