MALT1 regulates the gene expression network of MYC in MCL. (A) Gene expression profiling following pharmacologic inhibition of the proteolytic MALT1 activity using z-VRPR-fmk vs DMSO in Mino cells. Changes of gene expression were profiled at the indicated time points following treatment with z-VRPR-fmk. Each time point depicted the mean of log2-transformed expression ratios for 2 replicates. Gene expression changes were depicted according to the color scale shown. Genes that are involved in critical biological processes are highlighted. (B) Gene set enrichment analysis of a previously described MYC gene expression signature. The MYC signature was significantly enriched with genes that are downregulated following pharmacologic MALT1 inhibition using z-VRPR-fmk in Mino cells. (C) Expression levels of MALT1 target genes in MALT1-activated and MALT1-inactive MCL cell lines determined by quantitative PCR. mRNA levels of PFKM, CARD9, and MLKL were normalized to expression of GAPDH. Error bars indicate SDs. (D) MYC mRNA levels in Rec-1 and SP53 cells following shRNA-mediated knockdown of MALT1 as measured by quantitative PCR. MYC mRNA levels were normalized to expression of GAPDH. Error bars indicate SDs. (E) Treatment with z-VRPR-fmk downregulated MYC protein in the MALT1-activated MCL cell lines Mino and Rec-1. In contrast, in the MALT1-inactive cell lines Maver-1 and Z-138, MYC was not affected by inhibition of MALT1 activity. Accumulation of full-length BCL10 in MALT1-activated MCL models after treatment with z-VRPR-fmk was used as a surrogate marker of MALT1 inhibition. (F) MALT1 shRNA #1 and #2 downregulated MYC protein in MALT1-activated MCLs (Rec-1 and SP53), but not in MALT1-inactive MCLs (Maver-1 and Z-138) at the indicated time points after shRNA induction as measured by western blotting. N.D., not detectable; N.S., not significant. *P < .05, **P < .01, ***P < .001.
