ABSTRACT: Multiple myeloma (MM) cells undergo metabolic reprogramming in response to a hypoxic and nutrient-deprived bone marrow microenvironment. However, it is unclear whether primary oncogenes in recurrent translocations drive metabolic heterogeneity that can present new vulnerabilities for therapeutic targeting. t(4;14) translocation leads to the universal overexpression of histone methyltransferase MMSET II that promotes plasma cell transformation through a global increase in H3K36me2. We identified PKCα as a novel epigenetic target that contributes to the oncogenic potential of MMSET II. RNA-sequencing of t(4;14) cell lines revealed a significant enrichment in the regulation of metabolic processes by PKCα, and the glycolytic gene, hexokinase 2 (HK2), is transcriptionally regulated by PKCα in a PI3K/Akt-dependent manner. Loss of PKCα displaces mitochondria-bound HK2 and reversed sensitivity towards the glycolytic blocker 3-Bromopyruvate. Additionally, we observed a metabolic shift to a less energetic state through the reduction in oxidative and glycolytic fluxes, resulting in an overall decrease in ATP production. We employed metabolomics and lactate emerged as a differential metabolite associated with PKCα. This conferred PKCα with immunomodulatory drug (IMiDs) resistance in a cereblon-independent manner and could be phenocopied by either overexpression of HK2 or direct supplementation of lactate. Altogether, we revealed novel insights into the epigenetic and metabolism crosstalk in MM and the opportunity for therapeutic intervention that leverages on the distinct metabolic program in t(4;14) myeloma.
Project description:Multiple myeloma (MM) is characterized by recurrent chromosomal translocations. The multiple myeloma SET domain (MMSET), identified by its fusion to the IgH locus in t(4;14) MM, is universally overexpressed and has been suggested to play an important role in tumorigenicity in t(4;14) MM. In order to identify downstream functional targets of MMSET, we knocked down MMSET expression with shRNAs in KMS11, a t(4;14) MM cell line, and identified differentially expressed genes by gene expression microarray analysis.
Project description:Multiple myeloma (MM) is characterized by recurrent chromosomal translocations. The translocation t(4;14)(p16;q32) is one of the most common translocation in MMs, affecting 15% of patients, and is associated with very poor prognosis. The histone methyltransferase (HMTase) MMSET is universally overexpressed in t(4;14) MM as a result of the t(4;14) translocation. MMSET is capable of producing 3 major isoforms, the full length MMSET II, short isoforms REIIBP and MMSET I. MMSET II has been suggested to play an important tumorigenic role in t(4;14) MM, but little is yet known about whether and how the MMSET short isoforms contribute to MM tumorigenesis. The aim of this study is to characterize MMSET I roles and determine its downstream targets in t(4;14) MM. In t(4;14) MM cells MMSET I knockdown with shRNAs induced cell apoptosis, reduced colony formation and inhibited tumorigenicity in vivo. We also found MMSET I knockdown decreased GLO1 expression, and ectopic MMSET I increased GLO1 expression, suggesting that MMSET I is an upstream regulator of GLO1. Further analysis indicated that MMSET I bound to GLO1 promoter region and depended on its C-terminus to regulate GLO1 expression. Our preliminary data suggested that MMSET I is an oncoprotein and could regulate GLO1 expression in t(4;14) multiple myeloma cells.
Project description:The MMSET (Multiple Myeloma SET domain) protein is overexpressed in multiple myeloma patients with the translocation t(4;14). Although studies have shown the involvement of MMSET/WHSC1 in development, its mode of action in the pathogenesis of multiple myeloma (MM) is largely unknown. We found that MMSET is a major regulator of chromatin structure and transcription in t(4;14) MM cells. High levels of MMSET correlate with an increase in lysine 36 methylation of histone H3 and a decrease in lysine 27 methylation across the genome, leading to a more open structural state of the chromatin. Loss of MMSET expression alters adhesion properties, suppresses growth and induces apoptosis in MM cells. Consequently, genes affected by high levels of MMSET are implicated in the p53 pathway, cell cycle regulation and integrin signaling. Regulation of many of these genes required functional histone methyl-transferase (HMT) activity of MMSET. These results implicate MMSET as a major epigenetic regulator in t(4;14)+ MM.
Project description:The MMSET (Multiple Myeloma SET domain) protein is overexpressed in multiple myeloma patients with the translocation t(4;14). Although studies have shown the involvement of MMSET/WHSC1 in development, its mode of action in the pathogenesis of multiple myeloma (MM) is largely unknown. We found that MMSET is a major regulator of chromatin structure and transcription in t(4;14) MM cells. High levels of MMSET correlate with an increase in lysine 36 methylation of histone H3 and a decrease in lysine 27 methylation across the genome, leading to a more open structural state of the chromatin. Loss of MMSET expression alters adhesion properties, suppresses growth and induces apoptosis in MM cells. Consequently, genes affected by high levels of MMSET are implicated in the p53 pathway, cell cycle regulation and integrin signaling. Regulation of many of these genes required functional histone methyl-transferase (HMT) activity of MMSET. These results implicate MMSET as a major epigenetic regulator in t(4;14)+ MM. Total RNA was isolated from two different systems: an inducible knock down designed in the 5' region of MMSET. Upon addition of doxycycline we block MMSET expression. The second system we used was a repletion system. By retroviral infection of knock out cells for MMSET we restored the expression of MMSET wild type and two mutants of the protein: one active and one catalytically inactive. Triplicates of each sample were analyzed.
Project description:Multiple myeloma (MM) is characterized by recurrent chromosomal translocations. The multiple myeloma SET domain (MMSET), identified by its fusion to the IgH locus in t(4;14) MM, is universally overexpressed and has been suggested to play an important role in tumorigenicity in t(4;14) MM. In order to identify downstream functional targets of MMSET, we knocked down MMSET expression with shRNAs in KMS11, a t(4;14) MM cell line, and identified differentially expressed genes by gene expression microarray analysis. KMS11 cells were treated with shRNAs for 48 h. Total RNA was extracted by using the Qiagen RNeasy Mini kit (Germany). Gene expression was performed using the GeneChip Human Genome U133A Array (Affymetrix) following the manufacturerM-bM-^@M-^Ys instructions. Data analysis was performed using GeneSpring software from Agilent Technologies.
Project description:Hexokinase catalyzes the first committed step in glucose metabolism by phosphorylating glucose to produce glucose-6-phosphate. Highly glycolytic proliferating cells such as cancer cells take advantage of HK2 expression to accelerate glucose metabolism even in the presence of oxygen. This acceleration not only provides sufficient glycolytic intermediates to support the anabolic demands of the cells but also inevitably accompanies increased formation of metabolic end products such as lactate. Currently, the effect of lactate caused by HK2-mediated metabolic alteration is largely unknown. A recent study found that lactate plays a role in an epigenetic alteration known as histone lactylation. Here, using RNA-seq and CUT&Tag chromatin profiling, we study the effect of HK2 and lactate on gene expression via histone lactylation (H3K18la).
Project description:Hexokinase catalyzes the first committed step in glucose metabolism by phosphorylating glucose to produce glucose-6-phosphate. Highly glycolytic proliferating cells such as cancer cells take advantage of HK2 expression to accelerate glucose metabolism even in the presence of oxygen. This acceleration not only provides sufficient glycolytic intermediates to support the anabolic demands of the cells but also inevitably accompanies increased formation of metabolic end products such as lactate. Currently, the effect of lactate caused by HK2-mediated metabolic alteration is largely unknown. A recent study found that lactate plays a role in an epigenetic alteration known as histone lactylation. Here, using RNA-seq and CUT&Tag chromatin profiling, we study the effect of HK2 and lactate on gene expression via histone lactylation (H3K18la).
Project description:We investigated EZH2 binding in the presence and absence of MMSET protein. MMSET overexpression in t(4;14)+ myeloma leads to global loss of H3K27 methylation and redistribution of EZH2 binding throughout the genome
Project description:We performed gene expression profiling to understand the mechansims of cytotoxic effects of an MMSET inhibitor on t(4;14)-positive multiple myeloma cells.
Project description:We investigated EZH2 binding in the presence and absence of MMSET protein. MMSET overexpression in t(4;14)+ myeloma leads to global loss of H3K27 methylation and redistribution of EZH2 binding throughout the genome ChIP-seq for EZH2 in two cell types