Histone deacetylases (HDAC) that regulate gene expression are being explored as cancer therapeutic targets. In this study, we focused on HDAC6 based on its ability to inhibit cancerous Hsp90 chaperone activities by disrupting Hsp90/p23 interactions. To identify novel HDAC6 inhibitors, we employed a dual-luciferase reporter system in cell culture and living mice by bioluminescence imaging (BLI). Based on existing knowledge, a library of hydrazone compounds was generated for screening by coupling cinnamic hydroxamates with aldehydes and ketones. Potency and selectivity were determined by in vitro HDAC profiling assays with further evaluation to inhibit Hsp90(α/β)/p23interactions by BLI. In this manner, we identified compound 1A12 as a dose-dependent inhibitor of Hsp90(α/β)/p23 interactions, UKE-1 myeloid cell proliferation, p21waf1 upregulation and acetylated histone H3 levels. 1A12 was efficacious in tumor xenografts expressing Hsp90(α/β)/p23 reporters relative to carrier control treated mice as determined by BLI. Small animal 18F-FDG PET/CT imaging on the same cohort showed that 1A12 also inhibited glucose metabolism relative to control subjects. Ex vivo analyses of tumor lysates showed that 1A12 administration upregulated acetylated-H3 by ~3.5-fold. Taken together our results describe the discovery and initial preclinical validation of a novel selective HDAC inhibitor.

Metastatic recurrence is the leading cause of cancer-related deaths in patients with colorectal carcinoma. To capture the molecular underpinnings for metastasis and tumor progression, we performed integrative network analysis on 11 independent human colorectal cancer gene expression datasets and applied expression data from an immunocompetent mouse model of metastasis as an additional filter for this biologic process. In silico analysis of one metastasis-related coexpression module predicted nuclear factor of activated T-cell (NFAT) transcription factors as potential regulators for the module. Cells selected for invasiveness and metastatic capability expressed higher levels of NFATc1 as compared with poorly metastatic and less invasive parental cells. We found that inhibition of NFATc1 in human and mouse colon cancer cells resulted in decreased invasiveness in culture and downregulation of metastasis-related network genes. Overexpression of NFATc1 significantly increased the metastatic potential of colon cancer cells, whereas inhibition of NFATc1 reduced metastasis growth in an immunocompetent mouse model. Finally, we found that an 8-gene signature comprising genes upregulated by NFATc1 significantly correlated with worse clinical outcomes in stage II and III colorectal cancer patients. Thus, NFATc1 regulates colon cancer cell behavior and its transcriptional targets constitute a novel, biologically anchored gene expression signature for the identification of colon cancers with high risk of metastatic recurrence. Cancer Res; 74(23); 1–11. ©2014 AACR.

Metastatic recurrence is the leading cause of cancer death in patients with colorectal carcinoma. In order to capture the molecular underpinnings for metastasis and tumor progression, we performed integrative network analysis on 11 independent colorectal cancer gene expression data sets and applied expression data from an immuncompetenet mouse model of metastasis as an additional filter for this biological process. In silico analysis of one metastasis-related co-expression module predicted Nuclear Factor of Activated T-cell (NFAT) transcription factors as potential regulators for the module. Cells selected for invasiveness and metastatic capability expressed higher levels of NFATc1 as compared with poorly metastatic and less invasive parental cells. We found that inhibition of NFATc1 in human and mouse colon cancer cells resulted in decreased invasiveness in culture and down-regulation of metastasis-related network genes. Overexpression of NFATc1 significantly increased the metastatic potential of colon cancer cells while inhibition of NFATc1 reduced metastasis grown in an immunocompetent mouse model. Finally, we found that an 8-gene signature comprising genes up-regulated by NFATc1 significantly correlated with worse clinical outcomes in stage II and III colorectal cancer patients. Thus, NFATc1 regulates colon cancer cell behavior and its transcriptional targets constitute a new, biologically-anchored gene expression signature for the identification of colon cancers with high risk of metastatic recurrence.

Mutations in BRAF are present in the majority of patients with melanoma, rendering these tumors sensitive to targeted therapy with BRAF and MEK inhibitors. Unfortunately, resistance almost invariably develops. Recently, a phenomenon called “phenotype switching” has been identified as an escape route. By switching from a proliferative to an invasive state, melanoma cells can acquire resistance to these targeted therapeutics. Interestingly, phenotype switching bears a striking resemblance to the epithelial-to-mesenchymal–like transition that has been described to occur in cancer stem cells in other tumor types. We propose that these changes are manifestations of one and the same underlying feature, namely a dynamic and reversible phenotypic tumor cell plasticity that renders a proportion of cells both more invasive and resistant to therapy. At the same time, the specific characteristics of these tumor cell populations offer potential for being explored as target for therapeutic intervention. Cancer Res; 74(21); 1–5. ©2014 AACR.

Adult T-cell leukemia/lymphoma (ATL) is a human T-cell leukemia virus type-1–induced neoplasm with four clinical subtypes: acute, lymphoma, chronic, and smoldering. Although the chronic type is regarded as indolent ATL, about half of the cases progress to acute-type ATL. The molecular pathogenesis of acute transformation in chronic-type ATL is only partially understood. In an effort to determine the molecular pathogeneses of ATL, and especially the molecular mechanism of acute transformation, oligo-array comparative genomic hybridization and comprehensive gene expression profiling were applied to 27 and 35 cases of chronic and acute type ATL, respectively. The genomic profile of the chronic type was nearly identical to that of acute-type ATL, although more genomic alterations characteristic of acute-type ATL were observed. Among the genomic alterations frequently observed in acute-type ATL, the loss of CDKN2A, which is involved in cell-cycle deregulation, was especially characteristic of acute-type ATL compared with chronic-type ATL. Furthermore, we found that genomic alteration of CD58, which is implicated in escape from the immunosurveillance mechanism, is more frequently observed in acute-type ATL than in the chronic-type. Interestingly, the chronic-type cases with cell-cycle deregulation and disruption of immunosurveillance mechanism were associated with earlier progression to acute-type ATL. These findings suggested that cell-cycle deregulation and the immune escape mechanism play important roles in acute transformation of the chronic type and indicated that these alterations are good predictive markers for chronic-type ATL. Cancer Res; 74(21); 1–10. ©2014 AACR.