RANBP9 and RANBP10 cooperate in regulating non-small cell lung cancer proliferation.

Background: RANBP9 and RANBP10, also called Scorpins, are essential components of the C-terminal to LisH (CTLH) complex, an evolutionarily conserved poorly investigated multisubunit E3 ligase. Their role in non-small cell lung cancer (NSCLC) is unknown.

Methods: In this study, first we used stable loss-of function and overexpression inducible cell lines to investigate the ability of either RANBP9 or RANBP10 to form their own functional CTLH complex. Then, we probed lysates from patient tumors and analyzed data from publicly available repositories to investigate the expression of RANBP9 and RANBP10. Finally, we used inducible cell lines in vitro to recapitulate the expression observed in patients and investigate the changes of the proteome and the ubiquitylome associated with either RANBP9 or RANBP10 in NSCLC.

Results: Here, we show that the two Scorpins are both expressed in NSCLC cells and that either of them can independently support the formation of the CTLH complex. Short-term experiments revealed that the RANBP9 and RANBP10 proteins balance each other in terms of expression, and the acute overexpression of one or the other results in significant reshaping of the NSCLC cell proteome and ubiquitylome. A higher RANBP9/RANBP10 ratio is associated with greater proliferation in both NSCLC cell lines and patients. Acute increased expression of RANBP10 slows NSCLC cell proliferation and decreases the level of proliferation-associated proteins, including key players in DNA replication.

Conclusions: We present evidence that the Scorpins act as partial antagonists and work together as one sophisticated rheostat to modulate the CTLH complex ubiquitylation output, which regulates cell proliferation and other key biological processes in NSCLC. These results suggest that the two Scorpins can be considered as targets for the treatment of NSCLC.