Genetic Insusceptibility Mediated Inflammation Contributes to Bortezomib-Induced Peripheral Neuropathy

Introduction: Chemotherapy-induced peripheral neuropathy (CIPN) is a disabling pain condition resulting from chemotherapy for cancer. CIPN-inducing drug bortezomib is widely used in multiple myeloma (MM) treatment. The pathogenesis of bortezomib-induced peripheral neuropathy (BIPN) is poorly understood. Our study reported here elucidates the murine transcriptomic modifications in oxaliplatin- and cisplatin-induced CIPN and whole exome sequencing (WES) features in MM patients with BIPN.

Methods: RNA sequencing (RNA-seq) data of murine spinal cords were retrieved under the GEO accession numbers GSE253183 and GSE125002 to investigate transcriptomic modifications in oxaliplatin- and cisplatin-induced CIPN. Mononuclear cells isolated from the peripheral blood of newly diagnosed MM patients, either with (n=8) or without (n=12) BIPN after treated with 4 cycles of bortezomib-included regimens, were processed for WES using the Illumina Hiseq X platform and analyzed by bcftools and maftools.

Results: Gene Ontology (GO) Biological Process (BP) enrichment analysis with differently expressed genes (DEGs) from GSE253183 and GSE125002 indicated the upregulation of inflammatory processes. The downregulated genes were found to be related with neuronal functions, suggesting the suppression or impairment of normal neuronal activities. The Molecular Function (MF) analysis revealed alterations in ion channel activity, cell adhesion molecule binding and epigenetic alterations, particularly a decrease in histone H3 methyltransferase activity. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis also showed the DEGs enrichment in pathways associated with inflammation, such as cell adhesion molecules and leukocyte trans endothelial migration.

Compared with MM patients without BIPN, WES analysis demonstrated more missense mutations in patients with BIPN. The top 10 mutated genes were MKI67, TTN, MUC5B, RYR1, ZNF133, SRRM2, MUC3A, OBSCN, FAT1 and TMEM92. When screening genes with high mutation rates and more than 20 missense variants, zinc-finger (ZNF) protein family members, which were documented to be important in neurodegenerative and neurodevelopmental disorders, appeared in our results. The co-occurring and exclusiveness analysis of high-risk mutated genes illustrated the co-occurrences between ZNF family members.

An intersection analysis between DEGs from GSE253183 and GSE125002, and genes with high-frequency mutations from our WES analysis got a critical set of 100 genes. GO and KEGG analysis with these genes highlighted pathways that were integral to nervous system and critical biological processes, including the organization and assembly of synapses. High voltage-gated calcium channel activity, protein tyrosine kinase activity, and histone H3K4 trimethyltransferase activity were also enriched in GO MF analysis, which involved in neuroinflammation and oxidative stress. The KEGG pathway analysis showed DEGs enrichment in MAPK signaling pathway, which was regarded as downstream of NF- kappa B. These results illustrated that calcium signaling pathways, epigenetic changes and MAPK signaling pathway were important to inflammation-induced neuronal damage.

We then did strict intersection analysis with DEGs in oxaliplatin- and cisplatin-induced CIPN and mutated genes in BIPN patients. The conditions were set as: DEGs with high and moderate impact from GSE253183 and GSE125002; genes with SNPs mutated in more than 50% of samples and missense variant number higher than 20 in our WES study. This analysis yielded three genes: CACNA1H, CIC and ABLIM2, which were important to inflammation. Our molecular docking studies also confirmed the combination of bortezomib with CACNA1H, CIC and ABLIM2 proteins.

Conclusions: This study provides a comprehensive insight into the molecular mechanisms underlying BIPN. Inflammation induced by genetic insusceptibility is an important alteration in this process. The identification of key genes, such as CACNA1H, CIC and ABLIM2, highlights their mutations as potential biomarkers for BIPN. Therefore, preemptive genetic screening for these mutations could guide personalized treatment plans, potentially averting toxicities.