HBB-mafk axis drives lipid metabolism reprogramming and tumor progression in diffuse large B-cell lymphoma

Abstract Background: Diffuse large B cell lymphoma (DLBCL), a heterogeneous disease, constitutes the most common subtype of non-Hodgkin lymphoma. Genomic studies have identified several recurrent genetic mutations in DLBCL, such as MYD88 and CD79B. Approximately 30% to 40% of patients develop relapsed / refractory disease driven by gene alterations. Notably, a small subset of relapsed / refractory patients exhibit drug resistance in the absence of known high-risk factors, such as TP53 mutations. Current molecular classification systems remain incompletely established, underscoring the urgent need to explore novel mechanisms and therapeutic targets. In this study, we demonstrated that the HBB-MAFK axis may serve as a promising therapeutic target in DLBCL. Methods: DLBCL - related datasets were downloaded from GEO. Differential expression analysis was performed using the limma package. Candidate genes were subjected to multivariate Cox regression analysis and survival analysis to identify prognosis genes. HBB gene expression was further evaluated using tissue microarrays of DLBCL and adjacent tissues. Cell proliferation in DLBCL cell lines with stable knockdown or overexpression of the HBB gene was detected using the CCK-8 assay.Apoptosis was assessed by flow cytometry. Using Western blot technology to verify the expression of EMT marker. The differences of gene and signal pathway expression among different groups were analyzed by RNA-seq. Results: HBB was identified as prognostic gene. Differential gene analysis revealed that the expression level of the HBB gene in DLBCL tissues was significantly higher than that in normal tissues. Result from the multivariate Cox regression demonstrated that HBB was risk factor ( P-value = 0.0289, HR = 1.23 [1.02, 1.49] ). KM survival curves showed that patients with high HBB expression had poorer survival outcomes ( Log-rank, p ＜ 0.001, HR = 2.61 [1.46, 4.65] ). Age and high International Prognostic Index were independent prognostic factors. High HBB expression was associated with shorter PFS ( Log-rank, p ＜ 0.01, HR = 1.90 [1.18,3.06] ). Immunohistochemical staining of tissue microarrays showed that HBB protein expression was significantly elevated in DLBCL samples compared with adjacent tissues. CCK-8 results showed that the proliferation of WSU-DLCL2 and HBL-1 cell lines were inhibited after shRNA-mediated HBB knockdown. Flow cytometry results showed that the apoptosis rate of WSU-DLCL2 and HBL-1 cell lines increased after shRNA-mediated HBB knockdown. Conversely, overexpression of HBB in OCI-LY3 cells enhanced cell proliferation and reduced apoptosis. The results of Western blot showed that E-cadherin expression was increased and N-cadherin expression was decreased in shHBB cell lines, while the opposite trend was observed in HBB overexpressing cell line. RNA-seq analysis showed that, compared with the vector control group, a total of 97 transcription factors were significantly downregulated in the shHBB group ( Log2FC < –1, P-value < 0.05). Using the STRING database (v11.5), we identified 1,115 potential HBB-interacting proteins based on their combined scores. By intersecting the RNA-Seq and STRING datasets, 11 transcription factors were found to overlap. Among them, MAFK had the highest combined interaction score with HBB. GSEA showed that high HBB expression was significantly associated with enrichment of lipid metabolism pathways. Conclusion: Our findings suggest that HBB functions as a novel oncogenic factor in DLBCL by promoting proliferation, inhibiting apoptosis, modulating EMT, and potentially regulating lipid metabolism through interaction with the transcription factor MAFK. The HBB–MAFK axis may represent a promising therapeutic target in DLBCL.