Valosin-Containing Protein (VCP/p97) Mediates Neuroendocrine Differentiation in Prostate Cancer Cells Through Pim1...

Neuroendocrine Prostate Cancer (NEPC) is an aggressive type of androgen-independent prostate cancer (AIPC) associated with resistance to treatment. Valosin-containing protein (VCP/p97) has been found to be overexpressed in prostate cancer (PCa) cells undergoing neuroendocrine differentiation (NED) in response to interleukin-6 (IL-6). This study explores the molecular mechanisms through which VCP/p97 contributes to the progression of NEPC.

To investigate the role of VCP/p97 in the NED of PCa, we overexpressed the VCP/p97 in PCa cells. The molecular mechanisms underlying VCP/p97 induced NED were assessed by using western blot analysis and RT-PCR. Morphological changes were analyzed by using both bright field and confocal microscope. Lysotracker staining was performed to identify autophagy in VCP positive PCa cells.

In the present study, we found that VCP/p97 expression was notably higher in neuroendocrine (NE) cells NCI-H660 and PC3 than in other PCa cells. IL-6 treatment led to significant VCP/p97 overexpression in LNCaP and VCaP cells, with a marked increase in NE markers NSE and CHR-A. Inhibition of VCP/p97 using NMS-873 attenuated NED features, suggesting that VCP/p97 is required for NED progression. Moreover, VCP's role in NED is linked to its regulation via Pim1 in differentiating cells. Exogenous expression of VCP/p97 enhanced Pim1 and c-Myc expression, which were diminished upon VCP/p97 inhibition which is corroborated by reduced NED markers. Pim1 inhibition using AZD1208 and c-Myc knockdown further supported Pim1's involvement in VCP mediated NED. To promote NED, VCP/p97 regulated autophagy, as evidenced by increased LC3B and decreased SQSTM1/p62 levels upon VCP overexpression. Inhibition of VCP/p97 or autophagy disrupted NED and autophagic flux, arresting NED of LNCaP cells. Lysotracker staining and autophagic flux assays confirmed VCP's role in enhancing lysosomal-mediated autophagy and autophagolysosome formation. Furthermore, we show that AMPK activation, via LKB1 is essential for VCP/p97 mediated NED and autophagy.

VCP drives NED in PCa cells through a complex interplay involving the Pim1 axis and autophagy pathways. These findings highlight the potential of targeting VCP/p97 and its associated mechanisms as therapeutic strategies to inhibit NED progression.