Laura Pelletier

UNLABELLED: Molecular classifications defining new tumor subtypes have been recently refined with genetic and transcriptomic analyses of benign and malignant hepatocellular tumors. Here, we performed microRNA (miRNA) profiling in two series of fully annotated liver tumors to uncover associations between oncogene/tumor suppressor mutations and clinical and pathological features. Expression levels of 250 miRNAs in 46 benign and malignant hepatocellular tumors were compared to those of 4 normal liver samples with quantitative reverse-transcriptase polymerase chain reaction. miRNAs associated with genetic and clinical characteristics were validated in a second series of 43 liver tumor samples and 16 nontumor samples. miRNA profiling unsupervised analysis classified samples in unique clusters characterized by histological features (tumor/nontumor, P < 0.001; benign/malignant tumors, P < 0.01; inflammatory adenoma and focal nodular hyperplasia, P < 0.01), clinical characteristics [hepatitis B virus (HBV) infection, P < 0.001; alcohol consumption, P < 0.05], and oncogene/tumor suppressor gene mutations [beta-catenin, P < 0.01; hepatocyte nuclear factor 1alpha (HNF1alpha), P < 0.01]. Our study identified and validated miR-224 overexpression in all tumors and miR-200c, miR-200, miR-21, miR-224, miR-10b, and miR-222 specific deregulation in benign or malignant tumors. Moreover, miR-96 was overexpressed in HBV tumors, and miR-126* was down-regulated in alcohol-related hepatocellular carcinoma. Down-regulations of miR-107 and miR-375 were specifically associated with HNF1alpha and beta-catenin gene mutations, respectively. miR-375 expression was highly correlated to that of beta-catenin-targeted genes as miR-107 expression was correlated to that of HNF1alpha in a small interfering RNA cell line model. Thus, this strongly suggests that beta-catenin and HNF1alpha could regulate miR-375 and miR-107 expression levels, respectively. CONCLUSION: Hepatocellular tumors may have a distinct miRNA expression fingerprint according to malignancy, risk factors, and oncogene/tumor suppressor gene alterations. Dissecting these relationships provides a new hypothesis to understand the functional impact of miRNA deregulation in liver tumorigenesis and the promising use of miRNAs as diagnostic markers.

TO THE EDITOR: Peripheral T-cell lymphomas (PTCLs) are heterogeneous diseases resulting from the malignant transformation of mature T or natural killer cells. Their epidemiology varies widely, but PTCLs that derive from T follicular helper (TFH) cells, which include angioimmunoblastic T-cell

SMYD2 is a lysine methyltransferase that catalyzes the monomethylation of several protein substrates including p53. SMYD2 is overexpressed in a significant percentage of esophageal squamous primary carcinomas, and that overexpression correlates with poor patient survival. However, the mechanism(s) by which SMYD2 promotes oncogenesis is not understood. A small molecule probe for SMYD2 would allow for the pharmacological dissection of this biology. In this report, we disclose LLY-507, a cell-active, potent small molecule inhibitor of SMYD2. LLY-507 is >100-fold selective for SMYD2 over a broad range of methyltransferase and non-methyltransferase targets. A 1.63-Å resolution crystal structure of SMYD2 in complex with LLY-507 shows the inhibitor binding in the substrate peptide binding pocket. LLY-507 is active in cells as measured by reduction of SMYD2-induced monomethylation of p53 Lys370 at submicromolar concentrations. We used LLY-507 to further test other potential roles of SMYD2. Mass spectrometry-based proteomics showed that cellular global histone methylation levels were not significantly affected by SMYD2 inhibition with LLY-507, and subcellular fractionation studies indicate that SMYD2 is primarily cytoplasmic, suggesting that SMYD2 targets a very small subset of histones at specific chromatin loci and/or non-histone substrates. Breast and liver cancers were identified through in silico data mining as tumor types that display amplification and/or overexpression of SMYD2. LLY-507 inhibited the proliferation of several esophageal, liver, and breast cancer cell lines in a dose-dependent manner. These findings suggest that LLY-507 serves as a valuable chemical probe to aid in the dissection of SMYD2 function in cancer and other biological processes.Background: SMYD2 is a methyltransferase whose role in cancer is poorly understood and is lacking cell-active chemical tools.Results: We describe LLY-507, a small molecule inhibitor of SMYD2.Conclusion: LLY-507 is potent, selective, cell-active, and binds SMYD2 in a high resolution co-crystal.Significance: LLY-507 is a first-in-class cell-potent chemical probe that will be valuable in dissecting SMYD2 biology. SMYD2 is a lysine methyltransferase that catalyzes the monomethylation of several protein substrates including p53. SMYD2 is overexpressed in a significant percentage of esophageal squamous primary carcinomas, and that overexpression correlates with poor patient survival. However, the mechanism(s) by which SMYD2 promotes oncogenesis is not understood. A small molecule probe for SMYD2 would allow for the pharmacological dissection of this biology. In this report, we disclose LLY-507, a cell-active, potent small molecule inhibitor of SMYD2. LLY-507 is >100-fold selective for SMYD2 over a broad range of methyltransferase and non-methyltransferase targets. A 1.63-Å resolution crystal structure of SMYD2 in complex with LLY-507 shows the inhibitor binding in the substrate peptide binding pocket. LLY-507 is active in cells as measured by reduction of SMYD2-induced monomethylation of p53 Lys370 at submicromolar concentrations. We used LLY-507 to further test other potential roles of SMYD2. Mass spectrometry-based proteomics showed that cellular global histone methylation levels were not significantly affected by SMYD2 inhibition with LLY-507, and subcellular fractionation studies indicate that SMYD2 is primarily cytoplasmic, suggesting that SMYD2 targets a very small subset of histones at specific chromatin loci and/or non-histone substrates. Breast and liver cancers were identified through in silico data mining as tumor types that display amplification and/or overexpression of SMYD2. LLY-507 inhibited the proliferation of several esophageal, liver, and breast cancer cell lines in a dose-dependent manner. These findings suggest that LLY-507 serves as a valuable chemical probe to aid in the dissection of SMYD2 function in cancer and other biological processes. Background: SMYD2 is a methyltransferase whose role in cancer is poorly understood and is lacking cell-active chemical tools. Results: We describe LLY-507, a small molecule inhibitor of SMYD2. Conclusion: LLY-507 is potent, selective, cell-active, and binds SMYD2 in a high resolution co-crystal. Significance: LLY-507 is a first-in-class cell-potent chemical probe that will be valuable in dissecting SMYD2 biology.