CK2-dependent degradation of CBX3 dictates replication fork stalling and PARP inhibitor sensitivity.

DNA replication is a vulnerable cellular process, and its deregulation leads to genomic instability. Here, we demonstrate that chromobox protein homolog 3 (CBX3) binds replication protein A 32-kDa subunit (RPA2) and regulates RPA2 retention at stalled replication forks. CBX3 is recruited to stalled replication forks by RPA2 and inhibits ring finger and WD repeat domain 3 (RFWD3)-facilitated replication restart. Phosphorylation of CBX3 at serine-95 by casein kinase 2 (CK2) kinase augments cadherin 1 (CDH1)-mediated CBX3 degradation and RPA2 dynamics at stalled replication forks, which permits replication fork restart. Increased expression of CBX3 due to gene amplification or CK2 inhibitor treatment sensitizes prostate cancer cells to poly(ADP-ribose) polymerase (PARP) inhibitors while inducing replication stress and DNA damage. Our work reveals CBX3 as a key regulator of RPA2 function and DNA replication, suggesting that CBX3 could serve as an indicator for targeted therapy of cancer using PARP inhibitors.

Targeting LYPLAL1-mediated cGAS depalmitoylation enhances the response to anti-tumor immunotherapy.

Cyclic GMP-AMP synthase (cGAS) binds pathogenic and other cytoplasmic double-stranded DNA (dsDNA) to catalyze the synthesis of cyclic GMP-AMP (cGAMP), which serves as the secondary messenger to activate the STING pathway and innate immune responses. Emerging evidence suggests that activation of the cGAS pathway is crucial for anti-tumor immunity; however, no effective intervention method targeting cGAS is currently available. Here we report that cGAS is palmitoylated by ZDHHC9 at cysteines 404/405, which promotes the dimerization and activation of cGAS. We further identified that lysophospholipase-like 1 (LYPLAL1) depalmitoylates cGAS to compromise its normal function. As such, inhibition of LYPLAL1 significantly enhances cGAS-mediated innate immune response, elevates PD-L1 expression, and enhances anti-tumor response to PD-1 blockade. Our results therefore reveal that targeting LYPLAL1-mediated cGAS depalmitoylation contributes to cGAS activation, providing a potential strategy to augment the efficacy of anti-tumor immunotherapy.

ß-asarone inhibits the migration, invasion, and EMT of bladder cancer through activating ER stress.

BACKGROUND: ß-asarone (ß-as), a compound extracted from Acorus calamus, has been found to have anticancer effects on a variety of human cancers. However, the potential effect of ß-as on bladder cancer (BCa) remains unknown. METHODS: After exposure to ß-as, migration, invasion, and epithelial-mesenchymal transition (EMT) of BCa were determined by wound healing, transwell, and Western blot assays. Expression of proteins involved in the EMT and ER stress were explored by Western blot assays. Nude mouse xenograft model was served as the model system in vivo. RESULTS: The migration, invasion, and EMT of BCa were significantly inhibited after ß-as treatment. Further experiments revealed that endoplasmic reticulum (ER) stress is involved in ß-as-mediated metastasis inhibition. In addition, ß-as significantly up-regulated activating transcription factor 6 (ATF6), a branch of ER stress, and promoted its Golgi cleavage and nuclear localization. ATF6 silencing attenuated ß-as-mediated metastasis and EMT inhibition in BCa cells. CONCLUSION: Our data suggests that ß-as inhibits migration, invasion, and EMT of BCa by activating the ATF6 branch of ER stress. Thus, ß-as represents a potential candidate for BCa treatment.

ß-Ionone represses renal cell carcinoma progression through activating LKB1/AMPK-triggered autophagy.

ß-Ionone, the end ring analog of ß-carotenoids, has been proven to have an antitumor effect in a variety of cancers. In this study, we investigated the impact of ß-ionone on renal cell carcinoma (RCC) cell lines (786-O and ACHN) using colony formation assays, flow cytometry analysis, and western blot analysis. We found that ß-ionone effectively inhibited the proliferation of RCC cells in vitro, which was also confirmed in a xenograft model. Moreover, we found that ß-ionone could induce autophagy, as indicated by LC3 puncta in 786-O and ACHN cell lines and the expression of LC3 in ß-ionone-treated RCC cells. To further explore the underlying mechanism, we assessed liver kinase B1/AMP-activated protein kinase (LKB1/AMPK) signaling pathway activity, and the results showed that ß-ionone inhibited the proliferation of RCC cells by inducing autophagy via the LKB1/AMPK signaling pathway. In summary, our findings provide a new therapeutic strategy of ß-ionone-induced autophagy in RCC.

Deubiquitinase OTUD5 modulates mTORC1 signaling to promote bladder cancer progression.

The mechanistic (formally "mammalian") target of rapamycin (mTOR) pathway serves as a crucial regulator of various biological processes such as cell growth and cancer progression. In bladder cancer, recent discoveries showing the cancer-promoting role of mTOR complex 1 have attracted wide attention. However, the regulation of mTOR signaling in bladder cancer is complicated and the underlying mechanism remains elusive. Here, we report that the deubiquitinating enzyme, ovarian tumor domain-containing protein 5 (OTUD5), can activate the mTOR signaling pathway, promote cancer progression, and show its oncogenic potential in bladder cancer. In our study, we found that OTUD5 deubiquitinated a RING-type E3 ligase, RNF186, and stabilized its function. In addition, the stabilization of RNF186 further led to the degradation of sestrin2, which is an inhibitor of the mTOR signaling pathway. Together, we provide novel insights into the pathogenesis of bladder cancer and first prove that OTUD5 can promote bladder cancer progression through the OTUD5-RNF186-sestrin2-mTOR axis, which may be exploited in the future for the diagnosis and treatment of this malignancy.

Capsaicin inhibits the migration, invasion and EMT of renal cancer cells by inducing AMPK/mTOR-mediated autophagy.

Capsaicin (CAP), extracted from Capsicum fruits, has been reported to exhibit antitumor effects in various lines of cancer cells. However, the mechanism underlying its antitumor efficiency is not fully understood. Autophagy is a fundamental self-degradation process of cells that maintains homeostasis and plays a controversial role in tumor initiation and progression. The EMT is defined as a system regulating cells transformed from an epithelial-like phenotype into a mesenchymal phenotype by several internal and external factors, following the metastatic performance of the cells developed. The present study aimed to investigate the potential role of autophagy in CAP-induced antitumor effects in renal cell carcinoma (RCC) 786-O and CAKI-1 cell lines. The results revealed that CAP remarkably inhibited the migration and invasion of RCC cells in vitro and metastasis in vivo. Moreover, we found that the CAP treatment increased the formation of autophagolysosome vacuoles and LC3 yellow and red fluorescent puncta in RCC cells and upregulated the expression of LC3, suggesting that autophagy was induced by CAP in 786-O and CAKI-1 cell lines. Our further results demonstrated that CAP-induced autophagy was mediated by the AMPK/mTOR pathway. In conclusion, our study provides new knowledge of the potential relationship between autophagy and metastasis inhibition induced by CAP, which might be a promising therapeutic strategy in RCC.