Compared with previous bioinformatics studies on disease co-morbidity, this study has the following advantages: first, we guessed that MM and ONFH are correlated based on clinical experience, and we used R language multiple data packages to normalize the data by strict background calibration, normalization, elimination of batch effects and removal of outliers to ensure the reliability of the results as much as possible; the main advantage of WGCNA is that it can identify highly correlated genes and cluster them into gene modules for subsequent analysis. The main advantage of WGCNA is that it can identify highly correlated genes and cluster them into gene modules, and the resulting modules can show the correlation coefficients with clinical features for subsequent analysis. In addition, this study combined multiple biomolecules to analyze the co-morbidity mechanism from multiple bioinformatics perspectives in order to explore the potential mechanisms of MM and ONFH co-morbidity more comprehensively and deeply.
Through gene bank search, it was found that both MM and ONFH, as two complex malignant diseases in clinical practice, have a large gene network and a large number of overlapping predicted gene targets, indicating that they have a close relationship contact. Through degree of freedom screening, it was found that RPL14, RPL24, RPL36, RPL18, RPL12, RPL15, EIF3G, RPL10A, RPS19, and RPL35A have high degrees of freedom and are located at the core of the target interaction network, possibly related to MM and ONFH genes. Furthermore, by analyzing the expression of core genes and comparing their ROC performance, RPL24, RPL36, EIF3G, RPS19, and RPL35 were identified as candidate comorbidity genes.
RPS19, RPL35, RPL24, and RPL36 are genes of the gene family essential for pre-rRNA processing and maturation of the 40S ribosomal subunit. It has been reported that increased levels of ribosomal proteins are closely associated with the development of human cancers. Of course, under stress stress conditions, the opposite phenomenon occurs, leading to reduced ribosomal activity and decreased protein synthesis. Thus, the ribosome biogenesis is a key factor in the control of cell growth and proliferation, and any deregulation in this process Any deregulation in this process may lead to abnormal cell proliferation or pathological states such as cancer and metabolic disorders. At the same time, deletion in breast cancer cells will reduce the growth and vitality of cells, inhibit the release of elF 6 of 60S subunit, thus inhibiting the expression of hat dependent protein required for the survival and proliferation of breast cancer cells, and also inhibit the assembly of 80S ribosome and polymer. Research has shown that the upregulation of RPL24 transcription may be related to the occurrence of human colorectal tumors[17]. And it was found that RPS19 is overexpressed in bone marrow mesenchymal stem cells, and mutations in this gene cause Diamond-Blackfan anemia[18]. There are reports that RPS19 is significantly overexpressed in colorectal cancer tissues and cells, and a decrease in RPS19 expression can inhibit colorectal cancer cell growth and reduce tumorigenicity in nude mice[19]. Other studies have found that targeted up regulation of RPL15 expression in pancreatic cancer can inhibit the growth of pancreatic cancer cells [20]. EIF3G is one of the subunits of translation initiation factor 3 in eukaryotic cell and is necessary for protein translation initiation[21].However, these genes have not been reported in the study of MM and ONFH co-morbidities, and there are bioinformatics results that suggest that RPS19, RPL35, and RPL24 are core genes involved in the translational silencing and protein modification processes in the pathogenesis of multiple myeloma[22].
GO and KEGG analyses were able to clarify the network-like relationships among the targets, and GO analysis revealed that the biological processes were mostly focused on ribonucleoprotein complex biogenesis, cytoplasmic translation, ribonucleoprotein complex assembly, and further molecular functions such as DNA − binding transcription activator activity, RNA polymerase II − specific, structural constituent of ribosome. KEGG enrichment analysis revealed that after excluding non-specific pathways, it was mainly associated with PI3K-Akt, MAPK, Proteoglycans in cancer, Proteoglycans in cancer and Signaling pathways regulating pluripotency of stem cells and other signaling pathways. It has been demonstrated that high levels of phosphorylated GSK-3β inhibit osteogenic differentiation of stem cells and even accelerate osteoblast apoptosis in the establishment of animal models[23].Zhang et al. [24]found that atorvata action resulted in upregulation of miRNA-186, which assisted TLR4 in co-mediating the MAPK/NF-κB pathway to inhibit the process of ischemic necrosis of the femoral head, leading to apoptosis promoting autophagy. In addition, the PI3K/Akt signaling pathway plays a crucial role in regulating MM. Research has shown that in MM cells, formosanin C inhibits cell apoptosis and autophagy through the PI3K/AKT/mTOR signaling pathway, suggesting that changes in the malignant biological characteristics of MM cells depend to some extent on the activation of the PI3K/AKT/mTOR signaling pathway[25]. ROS/p38 MAPK can participate in the regulation of tumor growth and apoptosis processes, playing a key role in anticancer therapy. The accumulation of ROS in large quantities can lead to energy deficiency in MM cells, induce apoptosis, promote p38 MAPK protein phosphorylation, induce cell autophagy, and significantly promote MM cell apoptosis, which has a significant anticancer effect on MM[26].
Monoclonal gammopathy of undetermined significance (MGUS) as one of the early stages of MM, It has been observed that the expression levels of disaccharide chain proteoglycan, plasmin activator inhibitor 1 and periosteum element in bone marrow ECM of MGUS and MM patients increase, and the expression of fibronectin 2, protein lysine 6-oxidase and chitinase 3-like protein 1 decreases. These differentially expressed ECM proteins can promote the adhesion, invasion, migration and proliferation of MM malignant plasma cell [27]. The extracellular matrix is composed of collagen, fibrinogen, proteoglycans and other proteins involved in cell adhesion, migration and differentiation. The interaction between bone marrow ECM and cells plays an important role in the homing, proliferation, and differentiation of bone marrow cells. However, there is currently no report on the role of proteoglycans in the process of femoral head necrosis. This result shows that there is a certain correlation between the synthesis and metabolic process of proteoglycans and the occurrence of femoral head necrosis, which needs further experimental verification.
Furthermore, through immune infiltration analysis, it was found that many immune system components, such as B cells memory, T cells CD8, T cells follicular helper, T cells regulation (Tregs), Dendritic cells activated, Mast cells, B cells naive, and Plasma cells, are involved in the immune supervision and killing effects of malignant transformed osteomyeloma cells, and can cause functional disorders under the influence of myeloma cells, Even promoting and maintaining the growth and survival of myeloma, inducing the generation of drug resistance, and leading to recurrent disease[28, 29]. After the occurrence of osteonecrosis, the necrotic tissue and cells in the femoral head release various cytokines, which tend to activate inflammatory reactions with a large number of inflammatory cells, thereby disrupting the original immune balance, leading to greater bone destruction than osteogenesis, ultimately leading to irreversible collapse of the femoral head. More and more studies have shown that MM and ONFH are related immune inflammatory diseases[30, 31].
MM and ONFH both have complex pathological processes. In this study, the cross sections of two groups of large gene networks were excavated through bioinformatics methods, and the functional analysis of target genes found that they interact in inflammatory pathways and glycoprotein metabolism. The exploration of the biological functions and synergistic relationships of numerous core targets has provided possible directions for studying the mechanism of action and prevention and treatment between MM and ONFH to a certain extent, but the specific relationship still requires further research on clinical tissue information and basic experiments.