Single-cell RNA sequencing in double-hit lymphoma: IMPDH2 induces the progression of lymphoma by activating the PI3K/AKT/mTOR signaling pathway

Background: IMPDH2 is the rate-limiting enzyme of the de novo GTP synthesis pathway and has a key role in tumors; however, the specific mechanism underlying IMPDH2 activity in diffuse large B cell lymphoma (DLBCL) is still undetermined. This study aims to explore the potential mechanism of IMPDH2 in DLBCL, and its possible involvement in double-hit lymphoma (DHL), i.e., cases with translocations involving MYC and BCL2 and/or BCL6. Methods: Using single-cell sequencing and bioinformatics analysis to screen for IMPDH2. Exploring the differential expression of IMPDH2 and its correlation with prognosis through multiplexed immunofluorescence analysis. Using CCK8, EdU, clone formation assay, and animal model to analyze biological behavior changes after inhibiting IMPDH2. Explaining the potential mechanism of IMPDH2 in DLBCL by Western blot and multiplexed immunofluorescence. Results: Prognostic risk model was constructed by single-cell sequencing, which identified IMPDH2 as a DHLrelated gene. IMPDH2 was highly expressed in cell lines and tissues, associated with poor patient prognosis and an independent prognostic factor. In vitro and in vivo experiments showed that IMPDH2 inhibition significantly inhibited DHL cell proliferation. Flow cytometry showed apoptosis and cycle arrest. Western blot results suggested that c-Myc regulated the activation of PI3K/AKT/mTOR signaling pathway by IMPDH2 to promote tumor development in DHL. Moreover, multiplex immunofluorescence revealed decreased T-cell infiltration within the tumor microenvironment exhibiting concurrent high expression of IMPDH2 and PD-L1. Conclusions: Our results suggest that IMPDH2 functions as a tumor-promoting factor in DHL. This finding is expected to generate novel insights into the pathogenesis of these patients, thereby identifying potential therapeutic targets.

Automated summary

This study reveals that IMPDH2 plays a tumor-promoting role in diffuse large B cell lymphoma, especially in double-hit lymphoma cases. Inhibition of IMPDH2 significantly suppresses DHL cell proliferation, and c-Myc regulates the activation of the PI3K/AKT/mTOR signaling pathway through IMPDH2. Moreover, IMPDH2 expression is associated with decreased T-cell infiltration and concurrent high expression of PD-L1 within the tumor microenvironment. These findings provide insights into the pathogenesis of DHL and may lead to the identification of potential therapeutic targets.