SYNPO2 promotes the development of BLCA by upregulating the infiltration of resting mast cells and increasing the resistance to immunotherapy.

Synaptopodin 2 (SYNPO2) plays a pivotal role in regulating tumor growth, development and progression in bladder urothelial Carcinoma (BLCA). However, the precise biological functions and mechanisms of SYNPO2 in BLCA remain unclear. Based on TCGA database­derived BLCA RNA sequencing data, survival analysis and prognosis analysis indicate that elevated SYNPO2 expression was associated with poor survival outcomes. Notably, exogenous SYNPO2 expression significantly promoted tumor invasion and migration by upregulating vimentin expression in BLCA cell lines. Enrichment analysis revealed the involvement of SYNPO2 in humoral immune responses and the PI3K/AKT signaling pathway. Moreover, increased SYNPO2 levels increased the sensitivity of BLCA to PI3K/AKT pathway­targeted drugs while being resistant to conventional chemotherapy. In in vivo BLCA mouse models, SYNPO2 overexpression increased pulmonary metastasis of 5637 cells. High SYNPO2 expression led to increased infiltration of innate immune cells, particularly mast cells, in both nude mouse model and clinical BLCA samples. Furthermore, tumor immune dysfunction and exclusion score showed that patients with BLCA patients and high SYNPO2 expression exhibited worse clinical outcomes when treated with immune checkpoint inhibitors. Notably, in the IMvigor 210 cohort, SYNPO2 expression was significantly associated with the population of resting mast cells in BLCA tissue following PD1/PDL1 targeted therapy. In conclusion, SYNPO2 may be a promising prognostic factor in BLCA by modulating mast cell infiltration and exacerbating resistance to immune therapy and conventional chemotherapy.

Uricase sensitizes hepatocellular carcinoma cells to 5-fluorouracil through uricase-uric acid-UMP synthase axis

Conventional chemotherapy plays a key role in hepatocellular carcinoma (HCC) treatment, however, with intrinsic or acquired chemoresistance being a major constraint. Here, we aimed to identify potential target to reverse such chemoresistance. In the present study, we found significant difference in uridine monophosphate synthetase (UMPS) expression between 5-FU resistant and sensitive HCC cell lines and the overexpression or downregulation of UMPS impacted 5-FU response in HCC cells. We further found that inhibition of UMPS activity with uric acid at concentration present in human plasma decreased the 5-FU sensitivity of HCC cells, while reduction of uric acid levels with uricase improved the 5-FU sensitivity of HCC cells as well as colorectal cancer cells. In vivo studies also suggested that modulation of uric acid levels did affect 5-FU sensitivity of tumors. These data indicated that UMPS was correlated with the 5-FU resistance in HCC cells and uricase sensitized cancer cells to 5-FU through uricase-uric acid-UMP synthase axis, which provided a potential strategy to improve the efficacy of 5-FU-based chemotherapy for human cancers. (AU)