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Molecular Signatures of Multiple Myeloma Progression through Single Cell RNA-Seq

ABSTRACT: Multiple myeloma (MM) is a malignant plasma cell disorder with well-defined clonal genetic/cytogenetic abnormalities. However, cellular heterogeneity is a key factor in MM’s progression, therapeutic decision, and response to treatment. Single cell whole transcriptome profiling (scRNA-Seq) offers an opportunity to dissect this molecular heterogeneity during MM progression to better understand the disease and guide rational therapy. Here, we examined 597 CD138 positive cells from 15 patients at different stages of MM progression using scRNA-Seq. We selected 790 genes based on a Coefficient of Variation (CV) approach which organized cells into four clusters (L1-L4) based on unsupervised clustering. Plasma cells from each patient contained a mixed population of plasma cells at different state of aggressiveness based on gene expression signature reflecting the inter-cellular heterogeneous nature of MM. Cells in the L1 group is characterized by low level expression of genes involved in the oxidative phosphorylation, Myc targets, and mTORC1 signaling pathway having most cells from MGUS patients (p < 1.2x10-14). In contrast, low level of these genes in L1 group increased progressively and were the highest in the L4 group containing only cells from high-risk MM patients with t(4;14) translocations. Furthermore, 44 genes consistently overexpressed by pair-wised comparisons of the four groups strongly associated with a reduced overall survival in MM patients (APEX trial, p < 0.0001; Hazard Ratio (HR), 1.83; 95% CI, 1.33 to 2.52), particularly those in the bortezomib treated group (p < 0.0001; HR, 2.00; 95% CI, 1.39 to 2.89). No survival significance was observed for the dexamethasone treated group. Our study at the resolution of single cells showed that there is a mixed population of cells in each patient at different stages of MM progression and these cells can be organized into four different subgroups (L1 to L4). Consistent overexpression of the 44 genes from L1 to L4 groups is associated with patient outcome and treatment response. Our results show that oxidative phosphorylation, Myc target, and mTORC1 signaling genes are significant pathways for MM progression and affect MM prognosis and treatment stratification.

ORGANISM(S): Homo sapiens

PROVIDER: GSE118900 | GEO | 2018/11/17

REPOSITORIES: GEO

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Project description:Background: Low socioeconomic status (SES) has been linked to chronic stress and poorer health outcomes for marginalized communities in the U.S. The biological processes mediating the impact of SES on health to promote chronic diseases, such as cancer, remain poorly understood. Here, we aim to determine how changes in DNA methylation are linked to neighborhood-level socioeconomic deprivation, thereby promoting cancer initiation and progression through cancer- and immune-related pathways. Methods: We extracted DNA from 402 fresh frozen tissues from 289 women in the NCI-Maryland Breast Cancer Cohort, including 185 tumor samples, 113 additional paired adjacent normal samples, and 104 normal tissues from reduction mammoplasty. Census-tract level socioeconomic deprivation was measured via a Neighborhood Deprivation Index (NDI) using the geocoded addresses from our study participants. DNA methylation values were acquired using the Illumina Infinium MethylationEPIC 850K Beadchip. We conducted a differentially methylated probe (DMP) analysis between tumor and adjacent normal tissue to characterize methylation profiles by NDI status. We also used methylCIBERSORT to estimate immune cell subpopulation differences by tissue type and NDI status. Results: NDI was significantly associated with self-reported race in our cohort in both normal (p<0.0001, 95% CI -4.32, -2.58) and tumor (p<0.0001, 95% CI -4.22, -2.79) tissue. Our DMP analysis showed more significant methylation events (hypo- or hyper- methylation of the tumor tissue compared to adjacent normal tissue) in the NDI high group compared to the NDI low group. We also identified five CpG sites that were significantly hypomethylated in the tumors of the NDI high group, including two tumor suppressor genes, LRIG1 (p=1.99 x10-10) and WWOX (p=6.47 x 10-9). These methylation changes translated to an inverse relationship between gene expression for these tumor suppressor genes and NDI. We also identified significantly lower neutrophils in the NDI high tumors compared to NDI low tumors (p=0.001, 95% CI -0.112, -0.028). Conclusions: Overall, our analysis provides evidence that high neighborhood deprivation can lead to pro-tumorigenic changes in DNA methylation and gene expression that may impact the immune microenvironment, breast cancer progression, and overall survival.

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Molecular Signatures of Multiple Myeloma Progression through Single Cell RNA-Seq

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