PPP3CB Inhibits Cell Proliferation and the Warburg Effect in Bladder Cancer by Blocking PDHK1
Xiangmin Qiu1, Ziqing Jiang1, Yu Luo2
1The Ministry of Education Key Laboratory of Laboratory Medical Diagnostics, The College of Laboratory Medicine, Chongqing Medical University, 400016 Chongqing, China.
Background:
Cancer treatment has recently shifted towards metabolic approaches aimed at enhancing therapeutic efficacy. Somewhat surprisingly, a known regulator of energy metabolism in normal tissues, PPP3CB, is down-regulated in bladder cancer. This suggests that PPP3CB could exert an inhibitory effect on bladder cancer through its role in energy metabolism.
Methods:
To explore the above hypothesis, we employed non-targeted metabolism screening in bladder cancer cells with knockdown of PPP3CB. Glucose uptake and lactate production were carefully measured using specialized assay kits for glucose/lactic acid content. Western blot analysis was also used to evaluate the expression levels of pyruvate dehydrogenase kinase 1 (PDHK1) and p-PDHA1 in cells with PPP3CB knockdown. To substantiate the findings, co-immunoprecipitation (co-IP) experiments were performed to validate the interaction between PPP3CB and PDHK1. Various in vitro assays were also performed, including clone formation assay and Cell Counting Kit-8 (CCK8) viability assays. The in vivo anti-tumor potential of PPP3CB in bladder cancer was also studied using a nude mouse tumorigenesis model.
Results:
Significant down-regulation of PPP3CB was observed in bladder tumors, and potent anti-tumor effects of PPP3CB were observed in vitro. Investigation of the underlying mechanism by which PPP3CB hampers glycolysis in bladder cancer cells revealed that it interacted with PDHK1 to inhibit its protein stabilization. PDHK1 thus appears to be a crucial mediator through which PPP3CB exerts its inhibitory effects on bladder cancer cells.
Conclusions:
In summary, PPP3CB exerts strong inhibitory influences on bladder cancer cell proliferation and glycolysis via its destabilization of PDHK1. These results highlight the potential of PPP3CB as a novel regulator of the Warburg effect. Interestingly, the downregulation of PPP3CB in bladder cancer cells increases the Warburg effect, thereby generating more lactic acid and reshaping the tumor microenvironment so as to promote tumor cell proliferation.
Insights
The protein PPP1CB, a regulator of energy metabolism, inhibits bladder cancer growth by destabilizing PDHK1 and reducing the Warburg effect. Its downregulation in tumors promotes cancer progression.
Area of Science:
- Oncology
- Cancer Metabolism
- Molecular Biology
Background:
- Cancer treatment is increasingly focusing on metabolic pathways to improve efficacy.
- PPP1CB, a key energy metabolism regulator, is found to be downregulated in bladder cancer.
- This downregulation suggests PPP1CB may inhibit bladder cancer via its metabolic functions.
Purpose of the Study:
- To investigate the hypothesis that PPP1CB inhibits bladder cancer through its role in energy metabolism.
- To explore the mechanism by which PPP1CB affects bladder cancer cell glycolysis and proliferation.
- To evaluate the anti-tumor potential of PPP1CB in bladder cancer models.
Main Methods:
- Non-targeted metabolism screening in PPP1CB-knockdown bladder cancer cells.
- Measurement of glucose uptake and lactate production.
- Western blot analysis for PDHK1 and p-PDHA1 expression.
- Co-immunoprecipitation to confirm PPP1CB-PDHK1 interaction.
- In vitro proliferation and viability assays.
- In vivo tumorigenesis studies in nude mice.
Main Results:
- PPP1CB was significantly downregulated in bladder tumors, exhibiting potent in vitro anti-tumor effects.
- PPP1CB was found to interact with PDHK1, inhibiting its protein stabilization and thus hampering glycolysis.
- PDHK1 acts as a key mediator for PPP1CB's inhibitory effects on bladder cancer cells.
Conclusions:
- PPP1CB strongly inhibits bladder cancer cell proliferation and glycolysis by destabilizing PDHK1.
- PPP1CB emerges as a novel regulator of the Warburg effect in cancer.
- Reduced PPP1CB levels in bladder cancer enhance the Warburg effect, promoting tumor growth and altering the tumor microenvironment.
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