pevonedistat and Prostatic-Neoplasms

Prostate cancer (PCa) is the second leading cause of cancer-related deaths in men in Western countries, and there is still an urgent need for a better understanding of PCa progression to inspire new treatment strategies. Skp2 is a substrate-recruiting component of the E3 ubiquitin ligase complex, whose activity is regulated through neddylation. Slug is a transcriptional repressor involved in the epithelial-to-mesenchymal transition, which may contribute to therapy resistance. Although Skp2 has previously been associated with a mesenchymal phenotype and prostate cancer progression, the relationship with Slug deserves further elucidation. We have previously shown that a high Gleason score (≥8) is associated with higher Skp2 and lower E-cadherin expression. In this study, significantly increased expression of Skp2, AR, and Slug, along with E-cadherin downregulation, was observed in primary prostate cancer in patients who already had lymph node metastases. Skp2 was slightly correlated with Slug and AR in the whole cohort (Rs 0.32 and 0.37, respectively), which was enhanced for both proteins in patients with high Gleason scores (Rs 0.56 and 0.53, respectively) and, in the case of Slug, also in patients with metastasis to lymph nodes (Rs 0.56). Coexpression of Skp2 and Slug was confirmed in prostate cancer tissues by multiplex immunohistochemistry and confocal microscopy. The same relationship between these two proteins was observed in three sets of prostate epithelial cell lines (PC3, DU145, and E2) and their mesenchymal counterparts. Chemical inhibition of Skp2, but not RNA interference, modestly decreased Slug protein in PC3 and its docetaxel-resistant subline PC3 DR12. Importantly, chemical inhibition of Skp2 by MLN4924 upregulated p27 and decreased Slug expression in PC3, PC3 DR12, and LAPC4 cells. Novel treatment strategies targeting Skp2 and Slug by the neddylation blockade may be promising in advanced prostate cancer, as recently documented for other aggressive solid tumors.

Topics: Antigens, CD; Antineoplastic Agents; Cadherins; Cell Line, Tumor; Cell Survival; Cyclin-Dependent Kinase Inhibitor p27; Cyclopentanes; Docetaxel; Epithelial-Mesenchymal Transition; Gene Expression Regulation, Neoplastic; Humans; Lymphatic Metastasis; Male; NEDD8 Protein; Neoplasm Grading; PC-3 Cells; Prostate; Prostatic Neoplasms; Protein Processing, Post-Translational; Pyrimidines; Receptors, Androgen; RNA, Small Interfering; S-Phase Kinase-Associated Proteins; Snail Family Transcription Factors

Protein neddylation is a post-translational modification by a covalent conjugation with the neural precursor cell expressed, developmentally downregulated 8 (NEDD8). Although this process has been reported to participate in diverse cellular signaling, little is known about its role in cancer cell migration. Given a recent proteomics report showing that NEDD8 is downregulated in prostate cancer tissues versus normal prostate tissues, we tested the possibility that neddylation plays a role in cancer evolution, and then tried to identify target proteins of the neddylation.. The neddylation process was inhibited by transfecting cancer cells with NEDD8-targeting siRNAs or by treating the cells with a NAE1 inhibitor MLN4924. Cell migration was evaluated by an in vitro wound-healing assay and a Transwell migration assay. His/NEDD8-conjugated proteins were pulled down with nickel-affinity beads under a denaturing condition, and identified by Western blotting. All data were processed using the Microsoft Excel program and analyzed statistically by two-sided, unpaired Student's t-test.. Caveolin-1, which plays a critical role in cell migration, was identified to be conjugated with NEDD8. When the neddylation was inhibited, the phosphorylation of caveolin-1 at Tyr14 was augmented in PC3 and U373MG cells, thereby leading to increased cell migration. Such consequences by neddylation inhibition were abolished in the presence of a Src family kinase inhibitor PP2.. NEDD8 seems to inhibit the Src-mediated phosphorylation of caveolin-1 by modifying the structure of caveolin-1 protein, which blocks the migration of cancer cells. Although the neddylation process is currently regarded as an emerging target for cancer therapy, our results suggest the possibility that the inhibition of neddylation could facilitate cancer invasion or metastasis at least in some types of cancers.

Topics: Caveolin 1; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cyclopentanes; Humans; Male; NEDD8 Protein; Phosphorylation; Prostatic Neoplasms; Proteolysis; Pyrimidines; Signal Transduction; Ubiquitin-Activating Enzymes

Recent studies revealed that mutations in SPOP (Speckle-type POZ protein) occur in up to 15% of patients with prostate cancer. However, the physiological role of SPOP in regulating prostate tumorigenesis remains elusive. Here, we identified the Cdc20 oncoprotein as a novel ubiquitin substrate of SPOP. As such, pharmacological inhibition of Cullin-based E3 ligases by MLN4924 could stabilize endogenous Cdc20 in cells. Furthermore, we found that Cullin 3, and, to a less extent, Cullin 1, specifically interacted with Cdc20. Depletion of Cullin 3, but not Cullin 1, could upregulate the abudance of Cdc20 largely via prolonging Cdc20 half-life. Moreover, SPOP, the adaptor protein of Cullin 3 family E3 ligase, specifically interacted with Cdc20, and promoted the poly-ubiquitination and subsequent degradation of Cdc20 in a degron-dependent manner. Importantly, prostate cancer-derived SPOP mutants failed to interact with Cdc20 to promote its degradation. As a result, SPOP-deficient prostate cancer cells with elevated Cdc20 expression became resistant to a pharmacological Cdc20 inhibitor. Therefore, our results revealed a novel role of SPOP in tumorigenesis in part by promoting the degradation of the Cdc20 oncoprotein.

Topics: Antineoplastic Agents; Carbamates; Cdc20 Proteins; Cullin Proteins; Cyclopentanes; Diamines; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Enzyme Inhibitors; HeLa Cells; Humans; Male; Molecular Targeted Therapy; Mutation; Nuclear Proteins; Prostatic Neoplasms; Protein Interaction Domains and Motifs; Proteolysis; Pyrimidines; Repressor Proteins; Time Factors; Transfection; Ubiquitination

Inhibition of protein degradation by blocking Cullin-RING E3 ligases (CRLs) is a new approach in cancer therapy though of unknown risk because CRL inhibition may stabilize both oncoproteins and tumor suppressors. Probing CRLs in prostate cancer cells revealed a remarkable plasticity of cells with TMPRSS2-ERG translocation. CRL suppression by chemical inhibition or knockdown of RING component RBX1 led to reversible G0/G1 cell cycle arrest that prevented cell apoptosis. Conversely, complete blocking of CRLs at a higher inhibitor dose-induced cytotoxicity that was amplified by knockdown of CRL regulator Cand1. We analyzed cell signaling to understand how varying degrees of CRL inhibition translated to distinct cell fates. Both tumor suppressor and oncogenic cell signaling pathways and transcriptional activities were affected, with pro-metastatic Wnt/β-catenin as the most upregulated. Suppression of the NF-κB pathway contributed to anti-apoptotic effect, and androgen receptor (AR) and ERG played decisive, though opposite, roles: AR was involved in protective quiescence, whereas ERG promoted apoptosis. These data define AR-ERG interaction as a key plasticity and survival determinant in prostate cancer and suggest supplementary treatments that may overcome drug resistance mechanisms regulated by AR-ERG interaction.

Topics: Cell Line, Tumor; Cell Lineage; Cell Plasticity; Cell Proliferation; Cell Survival; Cyclopentanes; Gene Knockdown Techniques; Humans; Male; Models, Biological; NEDD8 Protein; Prostatic Neoplasms; Pyrimidines; Receptors, Androgen; Signal Transduction; Spheroids, Cellular; Transcription, Genetic; Transcriptional Regulator ERG; Ubiquitin-Protein Ligases; Ubiquitins

The neddylation pathway has been recognized as an attractive anticancer target in several malignancies, and its selective inhibitor, MLN4924, has recently advanced to clinical development. However, the anticancer effect of this compound against prostate cancer has not been well investigated. In this study, we demonstrated that the neddylation pathway was functional and targetable in prostate cancer cells. Specific inhibition of this pathway with MLN4924 suppressed the proliferation and clonogenic survival of prostate cancer cells. Mechanistically, MLN4924 treatment inhibited cullin neddylation, inactivated Cullin-RING E3 ligases (CRLs), and led to accumulation of tumor-suppressive CRLs substrates, including cell cycle inhibitors (p21, p27, and WEE1), NF-κB signaling inhibitor IκBα, and DNA replication licensing proteins (CDT1 and ORC1). As a result, MLN4924 triggered DNA damage, G2 phase cell cycle arrest, and apoptosis. Taken together, our results demonstrate the effectiveness of targeting the neddylation pathway with MLN4924 in suppressing the growth of prostate cancer cells, implicating a potentially new therapeutic approach for the men's cancer.

Topics: Apoptosis; Cell Line, Tumor; Cell Survival; Cullin Proteins; Cyclopentanes; DNA Damage; Humans; Male; Molecular Targeted Therapy; Prostatic Neoplasms; Pyrimidines; Signal Transduction; Ubiquitin-Protein Ligases; Ubiquitins