CDK1 serves as a therapeutic target of adrenocortical carcinoma via regulating epithelial-mesenchymal transition, G2/M phase transition, and PANoptosis.

Background: Adrenocortical carcinoma (ACC) is an extremely rare, aggressive tumor with few effective therapeutic options or drugs. Mitotane (Mtn), which is the only authorized therapeutic drug, came out in 1970 and is still the only first-line treatment for ACC in spite of serious adverse reaction and a high recurrence rate.

Methods: By in silico analysis of the ACC dataset in the cancer genome atlas (TCGA), we determined that high expression levels of cyclin-dependent kinase-1 (CDK1) were significantly related to the adverse clinical outcomes of ACC. In vitro and in vivo experiments were performed to evaluate the role of CDK1 in ACC progression through gain and loss of function assays in ACC cells. CDK1 inhibitors were screened to identify potential candidates for the treatment of ACC. RNA sequencing, co-immunoprecipitation, and immunofluorescence assays were used to elucidate the mechanism.

Results: Overexpression of CDK1 in ACC cell lines promoted proliferation and induced the epithelial-to-mesenchymal transition (EMT), whereas knockdown of CDK1 expression inhibited growth of ACC cell lines. The CDK1 inhibitor, cucurbitacin E (CurE), had the best inhibitory effect with good time-and dose-dependent activity both in vitro and in vivo. CurE had a greater inhibitory effect on ACC xenografts in nude mice than mitotane, without obvious adverse effects. Most importantly, combined treatment with CurE and mitotane almost totally eliminated ACC tumors. With respect to mechanism, CDK1 facilitated the EMT of ACC cells via Slug and Twist and locked ACC cells into the G2/M checkpoint through interaction with UBE2C and AURKA/B. CDK1 also regulated pyroptosis, apoptosis, and necroptosis (PANoptosis) of ACC cells through binding with the PANoptosome in a ZBP1-dependent way.

Conclusions: CDK1 could be exploited as an essential therapeutic target of ACC via regulating the EMT, the G2/M checkpoint, and PANoptosis. Thus, CurE may be a potential candidate drug for ACC therapy with good safety and efficacy, which will meet the great need of patients with ACC.