Castration immunoregulates toll-like receptor-4 in male bladder cancer
Leonardo Oliveira Reis1,2, Ana Clara Ciglioni Salustiano3, Diego Moreira Capibaribe3
1UroScience, School of Medical Sciences, State University of Campinas, UNICAMP, Campinas, SP, Brazil. reisleo.l@gmail.com.
Purpose:
Among diverse Pattern Recognition Receptors (PRRs), Toll-like receptor-4 (TLR-4) is a key urothelial trigger for innate immune response impacting urothelial bladder carcinoma (BC). Androgen activation promotes immunotolerance, playing an immunoregulatory role by unknown mechanisms. We explored the castration impact on urothelial TLR-4 modulation in carcinogenesis and immunotherapeutic scenario.
Methods:
Intact (SHAM) versus castrated male Fisher-344 rats were evaluated in 2 scenarios: (A) Carcinogenesis: After randomization to SHAM (n = 5) and Castration (n = 5), carcinogenesis was induced by four intravesical doses of 1.5 mg/kg n-methyl-n-nitrosourea (MNU) every 15 days. (B) Treatment: After ultrasonographic confirmed MNU-induced papillary BC on week 8, rats were randomized to SHAM (n = 5) and Castration (n = 5) and offered 6 weekly intravesical treatment of 106 CFU of bacillus Calmette Guerin (BCG) in 0.2 ml saline. After 15 weeks the urinary bladders underwent histopathology. Urothelial cell proliferation was measured by Ki-67 immunohistochemistry (IHC), and TLR-4 expression was quantified by IHC and WB.
Results:
Castration induced higher TLR-4 urothelial expression (p = 0.007) and anticarcinogenic effect with fewer urothelial tumors (60 vs. 80%) and lower urothelial cell proliferation compared to intact animals (p = 0.008). In the intravesical BCG treatment setting, castration has potentialized the BCG activation of TLR-4 (p = 0.007) with no residual in situ carcinoma compared to intact animals, suggesting the potential to amplify the BCG immune response.
Conclusion:
To our knowledge, this is the first description of TLR-4 urothelial expression hormonal modulation. The described castration-mediated immunomodulation will help to improve the knowledge of urothelial cancer gender diversities and PRRs modulations with treatment implications.
Insights
Castration increases Toll-like receptor-4 (TLR-4) expression in the urothelium, reducing bladder cancer and enhancing bacillus Calmette-Guérin (BCG) immunotherapy effectiveness. This hormonal modulation impacts urothelial cancer and pattern recognition receptor (PRR) responses.
Area of Science:
- Urology
- Immunology
- Oncology
Background:
- Toll-like receptor-4 (TLR-4) is a key pattern recognition receptor (PRR) in the urothelium, crucial for innate immune responses in urothelial bladder carcinoma (BC).
- Androgen activation is known to promote immunotolerance in BC, but its precise immunoregulatory mechanisms remain unclear.
Purpose of the Study:
- To investigate the impact of castration on urothelial TLR-4 expression.
- To evaluate the role of castration in bladder cancer development and response to immunotherapy.
Main Methods:
- Fisher-344 rats underwent either sham operation or castration.
- Carcinogenesis was induced using n-methyl-n-nitrosourea (MNU).
- Tumor-bearing rats received intravesical bacillus Calmette-Guérin (BCG) treatment, with subsequent analysis of urothelial cell proliferation (Ki-67) and TLR-4 expression (IHC, WB).
Main Results:
- Castration led to significantly higher urothelial TLR-4 expression and demonstrated an anticarcinogenic effect, with fewer tumors and reduced cell proliferation compared to intact rats.
- In the BCG treatment group, castration potentiated TLR-4 activation by BCG, resulting in no residual in situ carcinoma, suggesting an amplified immune response.
Conclusions:
- This study provides the first evidence of hormonal modulation of urothelial TLR-4 expression.
- Castration-mediated immunomodulation offers insights into gender differences in urothelial cancer and PRR modulation, with potential implications for treatment strategies.
