Novel regulation mechanism of adrenal cortisol and DHEA biosynthesis via the endogen ERAD inhibitor small VCP-interacting protein

Valosin containing protein (VCP): initiator, modifier, and potential drug target for neurodegenerative diseases

The AAA+ ATPase valosin containing protein (VCP) is essential for cell and organ homeostasis, especially in cells of the nervous system. As part of a large network, VCP collaborates with many cofactors to ensure proteostasis under normal, stress, and disease conditions. A large number of mutations have revealed the importance of VCP for human health. In particular, VCP facilitates the dismantling of protein aggregates and the removal of dysfunctional organelles. These are critical events to prevent malfunction of the brain and other parts of the nervous system. In line with this idea, VCP mutants are linked to the onset and progression of neurodegeneration and other diseases. The intricate molecular mechanisms that connect VCP mutations to distinct brain pathologies continue to be uncovered. Emerging evidence supports the model that VCP controls cellular functions on multiple levels and in a cell type specific fashion. Accordingly, VCP mutants derail cellular homeostasis through several mechanisms that can instigate disease. Our review focuses on the association between VCP malfunction and neurodegeneration. We discuss the latest insights in the field, emphasize open questions, and speculate on the potential of VCP as a drug target for some of the most devastating forms of neurodegeneration.

Differential Expression and Function of SVIP in Breast Cancer Cell Lines and In Silico Analysis of Its Expression and Prognostic Potential in Human Breast Cancer

The heterogeneity of cancer strongly suggests the need to explore additional pathways to target. As cancer cells have increased proteotoxic stress, targeting proteotoxic stress-related pathways such as endoplasmic reticulum stress is attracting attention as a new anticancer treatment. One of the downstream responses to endoplasmic reticulum stress is endoplasmic reticulum-associated degradation (ERAD), a major degradation pathway that facilitates proteasome-dependent degradation of unfolded or misfolded proteins. Recently, SVIP (small VCP/97-interacting protein), an endogenous ERAD inhibitor, has been implicated in cancer progression, especially in glioma, prostate, and head and neck cancers. Here, the data of several RNA-sequencing (RNA-seq) and gene array studies were combined to evaluate the SVIP gene expression analysis on a variety of cancers, with a particular focus on breast cancer. The mRNA level of SVIP was found to be significantly higher in primary breast tumors and correlated well with its promoter methylation status and genetic alterations. Strikingly, the SVIP protein level was found to be low despite increased mRNA levels in breast tumors compared to normal tissues. On the other hand, the immunoblotting analysis showed that the expression of SVIP protein was significantly higher in breast cancer cell lines compared to non-tumorigenic epithelial cell lines, while most of the key proteins of gp78-mediated ERAD did not exhibit such an expression pattern, except for Hrd1. Silencing of SVIP enhanced the proliferation of p53 wt MCF-7 and ZR-75-1 cells but not p53 mutant T47D and SK-BR-3 cells; however, it increased the migration ability of both types of cell lines. Importantly, our data suggest that SVIP may increase p53 protein levels in MCF7 cells by inhibiting Hrd1-mediated p53 degradation. Overall, our data reveal the differential expression and function of SVIP on breast cancer cell lines together with in silico data analysis.

1,25(OH)2 D3 induced vitamin D receptor signaling negatively regulates endoplasmic reticulum-associated degradation (ERAD) and androgen receptor signaling in human prostate cancer cells

Steroid hormone signaling is critical in the tumor progression and the regulation of physiological mechanisms such as endoplasmic reticulum-associated degradation (ERAD) and unfolded protein response (UPR) in prostate cancer. 1,25(OH)₂ D₃ is an active metabolite of vitamin D classified as a steroid hormone. It exhibits anti-tumor effects, including angiogenesis and suppression of cell cycle progression. Moreover, progressively reducing expression levels of vitamin D receptor (VDR) are observed in many cancer types, including the prostate. In the present study, we investigated the molecular action of 1,25(OH)₂ D₃ on ERAD, UPR and androgenic signaling. We found that 1,25(OH)₂ D₃ negatively regulated the expression level of ERAD components and divergently controlled the inositol-requiring enzyme 1⍺ (IRE1⍺) and protein kinase RNA-like ER kinase (PERK) branches of UPR in LNCaP human prostate cancer cells. Also, similar results were obtained with another human prostate cancer cell line, 22Rv1. More strikingly, we found that androgenic signaling is negatively regulated by VDR signaling. Also, molecular docking supported the inhibitory effect of 1,25(OH)₂ D₃ on AR signaling. Moreover, we found VDR signaling suppressed tumor progression by decreasing c-Myc expression and reducing the epithelial-mesenchymal transition (EMT). Additionally, 1,25(OH)₂ D₃ treatment significantly inhibited the 3D-tumor formation of LNCaP cells. Our results suggest that further molecular characterization of the action of VDR signaling in other cancer types such as estrogenic signal in breast cancer will provide important contributions to a better understanding of the roles of steroid hormone receptors in carcinogenesis processes.

Progesterone regulates the endoplasmic reticulum-associated degradation and Unfolded Protein Response axis by mimicking the androgenic stimulation in prostate cancer cells

BACKGROUND

Today, androgen receptor (AR)-mediated signaling mechanisms in prostate cancer are intensively studied. However, the roles of other steroid hormones in prostate cancer and their effects on androgenic signaling still remain a mystery. Recent studies focused on the androgen-mediated regulation of protein quality control mechanisms such as endoplasmic reticulum-associated degradation (ERAD) and unfolded protein response (UPR) in prostate cancer cells. Present study, we investigated the action of progesterone signaling on ERAD and UPR mechanisms and analyzed the crosstalk of progesterone signaling with androgenic signal in prostate cancer cells.

METHODS AND RESULTS

The mode of action of progesterone on ERAD, UPR and AR signaling in prostate cancer was investigated by cell culture studies using LNCaP and 22Rv1 cells. To this aim qRT-PCR, western-blotting assay, immunofluorescent microscopy, nuclear fractionation and bioinformatic analysis were used. Our results indicated that progesterone positively regulates mRNA and protein levels of ERAD components in LNCaP cells. Also, it induced the IRE⍺ and PERK branches of UPR signaling. Progesterone receptor antagonist effectively antagonized the progesterone-induced responses. We also had similar results in 22Rv1 cells. Also, we tested the effect of the pharmacologically reducing of IRE⍺ and PERK signaling on progesterone-induced ERAD. Additionally, we determined the presence of putative progesterone response elements (PREs) in the promoter regions of ERAD members by bioinformatic tool. More strikingly, we found progesterone regulates AR signaling by modulating the nuclear transactivation of AR.

CONCLUSION

Herein, we defined that progesterone hormone positively regulates ERAD and UPR mechanisms in prostate cancer cells and that progesterone contributes to the molecular biology of prostate cancer by regulating androgenic signaling. Mode of Action of Progesteron on Androgen sensitive prostate cancer cells.