Lin Ma

Background: While the immunomodulatory function of FAM174B in bladder cancer (BLCA) has yet to be fully elucidated, elucidating its biological mechanisms could potentially enhance immunotherapeutic outcomes for this malignancy.

Background: Neoadjuvant immune checkpoint blockade (nICB) has revolutionized cancer treatment, yet the underlying mechanisms of resistance in bladder cancer remain to be explored. Methods: We conducted single-cell RNA sequencing (scRNA-seq) on peripheral blood mononuclear cells, tumor tissues, adjacent normal tissues, and metastatic lymph nodes from 2 nICB-naïve and 10 nICB-treated patients with bladder cancer (5 responders and 5 non-responders). Spatial RNA sequencing was performed on tumor slides from two responders and four non-responders. Findings were validated by multiplex immunohistochemistry, mice orthotopic bladder cancer model, and flow cytometry assays. Results: nICB remodeled the tumor microenvironment of bladder cancer from both single-cell and spatial perspectives. scRNA-seq analysis revealed a significant increase in MYBL2 ^hi cancer stem cells (CSCs) among non-responders. Analysis of the myeloid population showed that SPP1+ macrophages associated with angiogenesis were linked to CD8+ T cell exclusion. Further investigation into cell–cell communication revealed a propensity for bidirectional crosstalk between MYBL2 ^hi CSCs and SPP1+ macrophages in non-responders. MYBL2 ^hi CSCs derived CCL15, which bound to CCR1 and induced SPP1 upregulation in macrophages which reciprocally enhanced bladder cancer stemness and resistance to nICB through the SPP1-ITGα9β1 axis. Additionally, we identified an aged CCL3+ neutrophil population that interacted with SPP1+ macrophages through a positive feedback loop, contributing to nICB resistance. Finally, in vivo studies demonstrated that combined MYBL2 knockdown and SPP1 targeting synergistically enhanced ICB efficacy in bladder cancer. Conclusions: Our research reveals transcriptomic characteristics associated with distinct therapeutic responses to nICB treatment, offering a foundation for optimizing personalized neoadjuvant strategies in bladder cancer.

Mesenchymal stem cells (MSCs) and cancer stem cells (CSCs) maintain bladder cancer (BCa) stemness and facilitate the progression, metastasis, drug resistance, and prognosis. Therefore, we aimed to decipher the communication networks, develop a stemness-related signature (Stem. Sig.), and identify a potential therapeutic target. BCa single-cell RNA-seq datasets (GSE130001 and GSE146137) were used to identify MSCs and CSCs. Pseudotime analysis was performed by Monocle. Stem. Sig. was developed by analyzing the communication network and gene regulatory network (GRN) that were decoded by NicheNet and SCENIC, respectively. The molecular features of the Stem. Sig. were evaluated in TCGA-BLCA and two PD-(L)1 treated datasets (IMvigor210 and Rose2021UC). A prognostic model was constructed based on a 101 machine-learning framework. Functional assays were performed to evaluate the stem traits of the hub gene. Three subpopulations of MSCs and CSCs were first identified. Based on the communication network, the activated regulons were found by GRN and regarded as the Stem. Sig. Following unsupervised clustering, two molecular subclusters were identified and demonstrated distinct cancer stemness, prognosis, immunological TME, and response to immunotherapy. Two PD-(L)1 treated cohorts further validated the performance of Stem. Sig. in prognosis and immunotherapeutic response prediction. A prognostic model was then developed, and a high-risk score indicated a poor prognosis. Finally, the hub gene SLC2A3 was found exclusively upregulated in extracellular matrix-related CSCs, predicting prognosis, and shaping an immunosuppressive tumor microenvironment. Functional assays uncovered the stem traits of SLC2A3 in BCa by tumorsphere formation and western blotting. The Stem. Sig. derived from MSCs and CSCs can predict prognosis and response to immunotherapy for BCa. Besides, SLC2A3 may serve as a promising stemness target facilitating cancer effective management.