Abstract 45P
Background
Urothelial carcinoma of bladder is the 9th most common cancer globally, associated with high mortality and recurrence. Failure in achieving durable clinical immune response depends upon a hostile immunosuppressive microenvironment. Tumor-associated macrophages (TAMs) are one of the major inundated myeloid cell populations in various solid tumors. They exhibit a spectrum of phenotypes either to stimulate or suppress immune responses. Cellular processes which lead to reversing the phenotype in TAMs to improve antitumor effects provide a new therapeutic avenue that has not been explored yet in UBC. Therefore, we aimed to investigate the therapeutic potential of autophagy pathway to reprogram the phenotype of TAMs in-vitro in UBC.
Methods
Phenotype and autophagy levels of macrophages were assessed by flow cytometry and immunofluorescence. Monocyte-derived macrophages were generated from PBMC of patients and supplemented with conditioned media from tumor single-cell suspension to obtain in-vitro TAMs. Under pharmacological inhibition of autophagy, phenotype, molecular expression and functionality of TAMs were assessed.
Results
TAMs were significantly elevated in UBC and displayed elevated M2 phenotype. of M1/M2 phenotype. Basal autophagy (LC-3, Beclin and p62) was elevated in TAMs. Upon modulating autophagy levels, we observed a shift in the phenotype of TAMs with a decrease in M2 phenotype and elevation in M1 phenotype. Further, autophagy inhibition to an increase in pro-inflammatory marker (IL-12, TNF-α) and decrease in (IL-10, TGF-β) at transcript and secretion levels. Functionally, autophagy altered the effects of TAMs on migration and proliferation of UBC cells. Moreover, the molecular signalling involving the HMGB-1/RAGE axis was observed as a potential axis determining the autophagy levels in TAMs.
Conclusions
Our results depict that TAMs acquire an immunosuppressive phenotype and elevated autophagy in UBC. Therapeutic modulation of autophagy in TAMs alleviates immunosuppressive and pro-tumor effects in UBC. Overall, our study provides a rationale for targeting autophagy in TAMs, which might offer a new therapeutic strategy in the management of UBC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
All India Institute of Medical Sciences, New Delhi, India.
Funding
Council for Scientific and Industrial research (CSIR).
Disclosure
The author has declared no conflicts of interest.