Probing Tumor Heterogeneity Among Multiple Myeloma Stages By Single Cell Sequencing

Multiple myeloma(MM)is the second largest blood cancer.The Revised International Staging System(R-ISS)has been used as a valid criterion for MM prognosis.However,the heterogeneity of MM cells based on R-ISS staging has not yet been discovered,so single-cell transcriptome sequencing was used to study the bone marrow samples of nine patients in the three stages of R-ISS stage.The main research content of this paper consists of the following parts.Firstly,single-cell transcriptome and copy number variation(CNV)maps of malignant plasma cells at each stage of R-ISS were established.After the identification of cell subsets,the CNV variant of plasma cells was analyzed,and high levels of CNV were found in phase III samples,which is related to the prognosis of patients and the malignancy of the disease.In situ fluorescence hybridization also confirms increased or absent DNA copy variation.Malignant plasma cell heterogeneity and gene expression modules.Abnormal proliferation of plasma cells is the dominant feature of MM,so plasma cells are reclustered into 9 subpopulations.Based on sample source analysis,P1-P5 were concentrated on samples from stage III.To investigate this phenomenon,quasi-timing analysis was applied to data mining in individual staging samples and found that PDIA6,LETM1,NES,MCM2,MCM4,XBP1,WARS,and ERPS genes were upregulated in the disease progression phase.To explore the upregulation mechanism of the above genes,transcription factor mining was performed on these genes using SCENIC analysis.Finally,the regulatory effects of STAT1,IRP1,PBX1,ATF6 and UQCRB on the above genes were discovered.It was verified on clinical samples and found that PDIA6 was activated by UQCRB through the oxidative phosphorylation pathway,while LETM1 was activated by STAT1 through the C-type lectin receptor signaling pathway.Monocytes in the bone marrow microenvironment show high heterogeneity at different R-ISS stages.The tumor microenvironment is an important synergistic factor in the development and development of MM,therefore,monocytes are reclustered into 8cell subsets(M1-M8).M3 and M4 subsets are mainly distributed in stage-III.stage,the differential genes of these two cell subsets are analyzed,in which CCL3L1,CXCL2,CCL4 are upregulated,for this purpose,JUND,ATF3,JUN and FOSB are found as their regulators.Plasma cell-monocytes communication promotes MM progression.To explore the mechanism of cell interaction between plasma cells and cells in the tumor microenvironment,receptor ligands between plasma cells and monocytes are analyzed.Some chemokines such as CCL3,CCL5,CCL3L1 bind to CCR1.SLC7A1 binds to CCL4 and CD47 binds to SIPRA;These specific binding methods can improve the research direction for in-depth exploration of tumors and their microenvironment.In summary,new upregulated genes were identified in MM with different R-ISS stages and the corresponding regulatory factors were explored.Cell signaling pathway analysis was used to demonstrate the pairing of receptor ligands of plasma cells/monocytes.These findings point out the direction for the study of the pathogenic mechanism of MM and lay a solid foundation for the research on the treatment of MM.