HNRNPL induced circFAM13B increased bladder cancer immunotherapy sensitivity via inhibiting glycolysis through IGF2BP1/PKM2 pathway

Abstract

Background The response rate to immunotherapy in patients with bladder cancer (BCa) remains relatively low. Considering the stable existence and important functions in tumour metabolism, the role of circRNAs in regulating immune escape and immunotherapy sensitivity is receiving increasing attention. Methods Circular RNA (circRNA) sequencing was performed on five pairs of BCa samples, and circFAM13B (hsa_circ_0001535) was screened out because of its remarkably low expression in BCa. Further mRNA sequencing was conducted, and the association of circFAM13B with glycolysis process and CD8+ T cell activation was confirmed. The functions of circFAM13B were verified by proliferation assays, glycolysis assays, BCa cells-CD8+ T cell co-culture assays and tumorigenesis experiment among human immune reconstitution NOG mice. Bioinformatic analysis, RNA–protein pull down, mass spectrometry, RNA immunoprecipitation, luciferase reporter assay and fluorescence in situ hybridization were performed to validate the HNRNPL/circFAM13B/IGF2BP1/PKM2 cascade. Results Low expression of circFAM13B was observed in BCa, and it was positively associated with lower tumour stage and better prognosis among patients with BCa. The function of CD8+ T cells was promoted by circFAM13B, and it could attenuate the glycolysis of BCa cells and reverse the acidic tumour microenvironment (TME). The production of granzyme B and IFN-γ was improved, and the immunotherapy (PD-1 antibodies) sensitivity was facilitated by the inhibition of acidic TME. Mechanistically, circFAM13B was competitively bound to the KH3-4 domains of IGF2BP1 and subsequently reduced the binding of IGF2BP1 and PKM2 3’UTR. Thus, the stability of the PKM2 mRNA decreased, and glycolysis-induced acidic TME was inhibited. The generation of circFAM13B was explored by confirming whether heterogeneous nuclear ribonucleoprotein L (HNRNPL) could promote circFAM13B formation via pre-mRNA back-splicing. Conclusions HNRNPL-induced circFAM13B could repress immune evasion and enhance immunotherapy sensitivity by inhibiting glycolysis and acidic TME in BCa through the novel circFAM13B/IGF2BP1/PKM2 cascade. Therefore, circFAM13B can be used as a biomarker for guiding the immunotherapy among patients with BCa.

Exosomes secreted by Fusobacterium nucleatum-infected colon cancer cells transmit resistance to oxaliplatin and 5-FU by delivering hsa_circ_0004085

“…To explore how Fn infection upregulated the levels of circRNA in intracellular and exosomes simultaneously, we examined the expression level of core members in hnRNPs family and found that hnRNP L and hnRNP A1 were significantly upregulated in CRC cells infected with Fn (F i g. 3 I). It has been reported that hnRNP L promotes circRNAs formation through regulating reverse splicing of pre-mRNA, while hnRNP A1 is able to load the non-coding RNA into exosomes [ 24 , 25 ]. RNA immunoprecipitation (RIP) was performed using hnRNP L or hnRNP A1 antibodies, and qRT-PCR revealed hnRNP L binding to pre-EPHB2 and hnRNP A1 binding to hsa_circ_0004085 (Fig.…”

Predicting Bladder Cancer Survival with High Accuracy: Insights from MAPK Pathway-related Genes

“…However, the overall prognosis remains poor 24 . Despite the increasing use of inhibitors targeting immune checkpoints such as PD-1 and PD-L1 in the treatment of bladder cancer, the e cacy of immunotherapy is still suboptimal, with a remission rate of about 25 percent 25 . Advances in next-generation sequencing technologies over the past few years have underscored the importance of identifying new molecular biomarkers in bladder cancer for accurately predicting patient prognosis, a critical aspect of clinical decision-making 26 .…”

Predicting bladder cancer survival with high accuracy: insights from MAPK pathway-related genes

“…However, the overall prognosis remains poor 34 . Despite the increasing use of inhibitors targeting immune checkpoints such as PD-1 and PD-L1 in the treatment of BLCA, the efficacy of immunotherapy is still suboptimal, with a remission rate of about 25% 35 . Advances in next-generation sequencing technologies over the past few years have underscored the importance of identifying novel molecular biomarkers in BLCA for accurately predicting patient prognosis, a critical aspect of clinical decision-making 36 .…”