β4-integrin-mediated cytotoxic activity of AexU in human prostate cancer PC3 cells
Masafumi Kumano1, Hideaki Miyake, Said K Abolghait
1Division of Urology, Kobe University Graduate School of Medicine, Kobe, Japan.
Abstract:
The present study aimed to characterize the cytotoxic activity of AexU, an effector-mediating type three secretion system (TTSS) of gram-negative bacteria, in human prostate cancer cells, focusing on the association with β4-integrin expression. The cytotoxic effects of AexU either alone or in combination with chemotherapeutic agents were evaluated using several human prostate cancer cell lines. Human prostate cancer PC3 cells, in which an expression vector containing siRNA targeting β4-integrin had been introduced, were established (PC3/sh-In), and the cytotoxic effects of AexU on the PC3/sh-In cells were compared with the PC3 cells that were transfected with a control vector (PC3/C). The expression levels of β4-integrin in the PC3 cells were markedly higher compared with those in the LNCaP or DU145 cells, and the cytotoxic effects of AexU in the PC3 cells were more pronounced compared with those in the LNCaP or DU145 cells. The sensitivity of the PC3 cells to docetaxel and cisplatin was significantly enhanced following treatment with AexU, resulting in a decrease in the IC50 of the two agents by ~90%. The cytotoxic effect of AexU in the PC3/C cells was more marked compared with that in the PC3/sh-In cells, and the phosphorylation of Akt in the PC3/C cells appeared to be significantly more inhibited by the treatment with AexU compared with the PC3/sh-In cells. In conclusion, treatment with AexU may be a useful therapeutic option for prostate cancer when β4-integrin is overexpressed. The treatment appears to exert its effects through growth inhibition and by enhancing the sensitivity of the cancer cells to chemotherapeutic agents.
Insights
AexU, a bacterial protein, shows promise in treating prostate cancer by inhibiting cancer cell growth and increasing sensitivity to chemotherapy, especially when beta-4 integrin is overexpressed.
Area of Science:
- Microbiology
- Oncology
- Cell Biology
Background:
- Prostate cancer remains a significant health concern, with a need for novel therapeutic strategies.
- Type three secretion systems (TTSS) in gram-negative bacteria deliver effector proteins that can modulate host cell functions.
- Beta-4 integrin (β4-integrin) is implicated in various cancers, including prostate cancer.
Purpose of the Study:
- To investigate the cytotoxic effects of the bacterial effector AexU on human prostate cancer cells.
- To explore the role of β4-integrin expression in mediating AexU's cytotoxicity.
- To assess AexU's potential in combination with standard chemotherapeutic agents.
Main Methods:
- Cytotoxicity assays were performed on human prostate cancer cell lines (PC3, LNCaP, DU145).
- PC3 cells were engineered to express β4-integrin-targeting siRNA (PC3/sh-In) or a control vector (PC3/C).
- The effects of AexU alone and in combination with docetaxel and cisplatin were evaluated, including IC50 determination and Akt phosphorylation analysis.
Main Results:
- AexU exhibited significant cytotoxic activity in prostate cancer cells, particularly in PC3 cells with high β4-integrin expression.
- AexU markedly enhanced the sensitivity of PC3 cells to docetaxel and cisplatin, reducing IC50 values by approximately 90%.
- AexU's cytotoxic effect and inhibition of Akt phosphorylation were more pronounced in PC3/C cells compared to PC3/sh-In cells, indicating β4-integrin's involvement.
Conclusions:
- AexU demonstrates potent cytotoxic effects against human prostate cancer cells.
- AexU can significantly potentiate the efficacy of common chemotherapeutic agents like docetaxel and cisplatin.
- Overexpression of β4-integrin may identify patients who could benefit from AexU-based prostate cancer therapy.
