Cheliensisin A (Chel A) induces apoptosis in human bladder cancer cells by promoting PHLPP2 protein degradation

Isorhapontigenin inhibition of basal muscle-invasive bladder cancer attributed to its downregulation of SNHG1 and DNMT3b

BACKGROUND

Bladder cancer (BC) is among the most prevalent malignant urothelial tumors globally, yet the prognosis for patients with muscle-invasive bladder cancer (MIBC) remains dismal, with a very poor 5-year survival rate. Consequently, identifying more effective and less toxic chemotherapeutic alternatives is critical for enhancing clinical outcomes for BC patients. Isorhapontigenin (ISO), a novel stilbene isolated from a Gnetum found in certain provinces of China, has shown potential as an anticancer agent due to its diverse anticancer activities. Despite its promising profile, the specific anticancer effects of ISO on BC and the underlying mechanisms are still largely unexplored.

METHODS

The anchorage-independent growth, migration and invasion of BC cells were assessed by soft agar and transwell invasion assays, respectively. The RNA levels of SOX2, miR-129 and SNHG1 were quantified by qRT-PCR, while the protein expression levels were validated through Western blotting. Furthermore, methylation-specific PCR was employed to assess the methylation status of the miR-129 promoter. Functional assays utilized siRNA knockdown, plasmid-mediated overexpression, and chemical inhibition approaches.

RESULTS

Our study demonstrated that ISO treatment significantly reduced SNHG1 expression in a dose- and time-dependent manner in BC cells, leading to the inhibition of anchorage-independent growth and invasion in human basal MIBC cells. This effect was accompanied by the downregulation of MMP-2 and MMP-9 and the upregulation of the tumor suppressor PTEN. Further mechanistic investigations revealed that SOX2, a key upstream regulator of SNHG1, played a crucial role in mediating the ISO-induced transcriptional suppression of SNHG1. Additionally, we found that ISO treatment led to a decrease in DNMT3b protein levels, which in turn mediated the hypomethylation of the miR-129 promoter and the subsequent suppression of SOX2 mRNA 3'-UTR activity, highlighting a novel pathway through which ISO exerts its anticancer effects.

CONCLUSIONS

Collectively, our study highlights the critical role of SNHG1 downregulation as well as its upstream DNMT3b/miR-129/SOX2 axis in mediating ISO anticancer activity. These findings not only elucidate the mechanism of action of ISO but also suggest novel targets for BC therapy.

Natural products and derivatives in renal, urothelial and testicular cancers: Targeting signaling pathways and therapeutic potential

BACKGROUND

Natural products have demonstrated significant potential in cancer drug discovery, particularly in renal cancer (RCa), urothelial carcinoma (UC), and testicular cancer (TC).

PURPOSE

This review aims to examine the effects of natural products on RCa, UC and TC.

STUDY DESIGN

systematic review METHODS: PubMed and Web of Science databases were retrieved to search studies about the effects of natural products and derivatives on these cancers. Relevant publications in the reference list of enrolled studies were also checked.

RESULTS

This review highlighted their diverse impacts on key aspects such as cell growth, apoptosis, metastasis, therapy response, and the immune microenvironment. Natural products not only hold promise for novel drug development but also enhance the efficacy of existing chemotherapy and immunotherapy. Importantly, we exert their effects through modulation of critical pathways and target genes, including the PI3K/AKT pathway, NF-κB pathway, STAT pathway and MAPK pathway, among others in RCa, UC, and TC.

CONCLUSION

These mechanistic insights provide valuable guidance for researchers, facilitating the selection of promising natural products for cancer management and offering potential avenues for further gene regulation studies in the context of cancer treatment.

The inhibitory effect of compound ChlA-F on human bladder cancer cell invasion can be attributed to its blockage of SOX2 protein

Sex-determining region Y-box 2 (SOX2), a well-known stemness biomarker, is highly expressed in a variety of cancers, including human highly invasive bladder cancer (BC). However, the role of SOX2 may vary in different kinds of malignancy. In the present study, we discovered that ChlA-F, a novel conformation derivative of isolate Cheliensisin A (Chel A), remarkably inhibits the invasive ability of human invasive BC cells through downregulation of SOX2 protein expression. We found that ChlA-F treatment dramatically decreases SOX2 protein expression in human high-grade invasive BC cells. Ectopic expression of SOX2 reversed ChlA-F inhibition of cell invasion ability in human bladder cancer cells, suggesting that SOX2 is a major target of ChlA-F during its inhibition of human BC invasion. Mechanistic studies revealed that ChlA-F downregulates SOX2 at both the protein degradation and protein translation levels. Further studies revealed that ChlA-F treatment induces HuR protein expression and that the increased HuR interacts with USP8 mRNA, resulting in elevation of USP8 mRNA stability and protein expression. Elevated USP8 subsequently acts as an E3 ligase to promote SOX2 ubiquitination and protein degradation. We also found that ChlA-F treatment substantially increases c-Jun phosphorylation at Ser63 and Ser73, initiating miR-200c transcription. The increased miR-200c directly binds to the 3'-UTR of SOX2 mRNA to suppress SOX2 protein translation. These results present novel mechanistic insight into understanding SOX2 inhibition upon ChlA-F treatment and provide important information for further exploration of ChlA-F as a new therapeutic compound for the treatment of highly invasive/metastatic human BC patients.

Transcriptionally elevation of miR-494 by new ChlA-F compound via a HuR/JunB axis inhibits human bladder cancer cell invasion

Muscle invasive bladder cancer (MIBC) is characterized by a poor overall survival rate in patients. Therefore, innovation and evaluation of idea anti-cancer compounds is of importance for reducing the mortality of MIBCs. The chemotherapeutic activity of ChlA-F, a novel C8 fluoride derivative of cheliensisin A with potent anti-neoplastic properties, was barely investigated. We reported here that ChlA-F treatment significantly induced miR-494 expression and suppressed cell invasion in human MIBC cells. Our results indicated that miR-494 was downregulated in M1 metastatic BC patients in comparison to non-metastatic (M0) BC patients, and such downregulation was also well correlated with over survival rate for MIBC patients. Mechanistically, ChlA-F-induced upregulation of miR-494 was due to a HuR-mediated increase in JunB mRNA stabilization and protein expression, which led to an increase in miR-494 transcription via directly binding to the miR-494 promoter region, while the upregulated miR-494 was able to bind the 3'-UTR region of c-Myc mRNA, resulting in decreased c-Myc mRNA stability and protein expression and further reducing the transcription of c-Myc-regulated MMP-2 and ultimately inhibiting BC invasion. Our results provide the first evidence showing that miR-494 downregulation was closely associated with BC metastatic status and overall BC survival, and ChlA-F was able to reverse the level of miR-494 with a profound inhibition of human BC invasion in human invasive BC cells. Our studies also reveal that ChlA-F is a promising therapeutic compound for BCs and miR-494 could also serve as a promising therapeutic target for the treatment of MIBC patients.

New compound ChlA-F induces autophagy-dependent anti-cancer effect via upregulating Sestrin-2 in human bladder cancer

ChlA-F is a novel conformation-derivative of Cheliensisin A, styryl-lactone isolates that show potent anti-tumor potential in vivo and vitro. However, the anti-cancer activity and its potential mechanisms underlying ChlA-F action have never been explored. In the present study, we evaluated the potency of ChlA-F on autophagy-mediated anchorage-independent growth inhibition in human high-grade invasive bladder cancer (BC) cells. We found that ChlA-F treatment significantly inhibited anchorage-independent growth of human BC cells by inducing autophagy in a Sestrin-2 (SESN2)-dependent fashion. Our results revealed that ChlA-F treatment specifically induced SESN2 expression via increasing its transcription and mRNA stability. On one hand, ChlA-F treatment markedly attenuated Dicer protein abundance, in turn abolishing miR-27a maturation and further relieving miR-27a binding directly to SESN2 mRNA 3'UTR, thereby promoting SESN2 mRNA stabilization. On the other hand, ChlA-F treatment promoted Sp1 abundance and consequently mediated SESN2 transcription. These results demonstrate that its activation of the autophagic pathway through specifically promoting SESN2 expression mediates the anti-cancer effect of ChlA-F, which offers insights into the novel anti-cancer effect of ChlA-F on BC, as well as providing therapeutic alternatives against human BC.

NF-κB p65 Overexpression Promotes Bladder Cancer Cell Migration via FBW7-Mediated Degradation of RhoGDIα Protein

BACKGROUND

Since invasive bladder cancer (BC) is one of the most lethal urological malignant tumors worldwide, understanding the molecular mechanisms that trigger the migration, invasion, and metastasis of BC has great significance in reducing the mortality of this disease. Although RelA/p65, a member of the NF-kappa B transcription factor family, has been reported to be upregulated in human BCs, its regulation of BC motility and mechanisms have not been explored yet.

METHODS

NF-κBp65 expression was evaluated in N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN)-induced high invasive BCs by immunohistochemistry staining and in human BC cell lines demonstrated by Western Blot. The effects of NF-κBp65 knockdown on BC cell migration and invasion, as well as its regulated RhoGDIα and FBW7, were also evaluated in T24T cells by using loss- and gain-function approaches. Moreover, the interaction of FBW7 with RhoGDIα was determined with immunoprecipitation assay, while critical role of ubiquitination of RhoGDIα by FBW7 was also demonstrated in the studies.

RESULTS

p65 protein was remarkably upregulated in the BBN-induced high invasive BCs and in human BC cell lines. We also observed that p65 overexpression promoted BC cell migration by inhibiting RhoGDIα expression. The regulatory effect of p65 on RhoGDIα expression is mediated by its upregulation of FBW7, which specifically interacted with RhoGDIα and promoted RhoGDIα ubiquitination and degradation. Mechanistic studies revealed that p65 stabilizing the E3 ligase FBW7 protein was mediated by its attenuating pten mRNA transcription.

CONCLUSIONS

We demonstrate that p65 overexpression inhibits pten mRNA transcription, which stabilizes the protein expression of ubiquitin E3 ligase FBW7, in turn increasing the ubiquitination and degradation of RhoGDIα protein and finally promoting human BC migration. The novel identification of p65/PTEN/FBW7/RhoGDIα axis provides a significant insight into understanding the nature of BC migration, further offering a new theoretical support for cancer therapy.