Adrenocortical carcinoma (ACC) is a rare but malignant tumor. Surgical removal, radiotherapy and combined chemotherapy are commonly used to treat ACC. Despite efforts for several decades, the mortality rate of ACC remains high after treatments. Therefore, identifying a novel therapeutic molecule is important to increase the survival rate of patients with ACC. The centrosome is a microtubule organizing center, and it also functions as a signaling hub to coordinate cell cycle progression. Deficiencies in the regulation of centrosome copy numbers may cause cell cycle arrest or even apoptosis. BI2536 is a polo like kinase 1-selective inhibitor and has been tested for the treatment of several types of cancer, including lung, oral and gastric cancer. However, to the best of our knowledge, its effects on ACC have not yet been examined. The present study revealed that BI2536 inhibited Y1 ACC cell proliferation in a time- and dose-dependent manner. BI2536 blocked cell cycle progression and also induced cell apoptosis as shown by flow cytometry. Furthermore, following BI2536 treatment, centrosome amplification was induced, which resulted in aberrant mitosis. In terms of the mechanism, BI2536 induced DNA damage as evidenced by γH2AX staining and comet assay, followed by activation of ATM serine/threonine kinase-ERK signaling to promote centrosome amplification. Therefore, the present study suggested that BI2536 could be used as an adjuvant therapy in the treatment of ACC, and also revealed the underlying molecular mechanism.

Testes control the development of male reproductive system. The testicular interstitial Leydig cells (Leydig cells) synthesize testosterone for promoting spermatogenesis and secondary sexual characteristics. Type A platelet-derived growth factor (PDGF-AA) is one of the most important growth factors in regulating Leydig cell growth and function. Knockout of PDGF-AA or its congenital receptor PDGFR-α leads to poor testicular development caused by reducing Leydig cell numbers, supporting PDGF-AA/PDGFR-α signaling regulates Leydig cell development. Primary cilium is a cellular antenna that functions as an integrative platform to transduce extracellular signaling for proper development and differentiation. Several receptors including PDGFR-α are observed on primary cilia for initiating signaling cascades in distinct cell types. Here we showed that PDGF-AA/PDGFR-α signaling promoted Leydig cells growth, migration, and invasion via primary cilia. Upon PDGF-AA treatment, AKT and ERK signaling were activated to regulate these cellular events. Interestingly, active AKT and ERK were detected around the base of primary cilia. Depletion of ciliary genes (IFT88 and CEP164) alleviated PDGF-AA-activated AKT and ERK, thus reducing Leydig cell growth, migration, and invasion. Thus, our study not only reveals the function of PDGF-AA/PDGFR-α signaling in maintaining testicular physiology but also uncovers the role of primary cilium and downstream signaling in regulating Leydig cell development.