miRNAs are important regulatory elements for gene expression that are involved in diverse physiologic and pathologic processes. Canonical miRNA biogenesis consists of a two-step processing, from primary transcripts (pri-miRNA) to precursor miRNAs (pre-miRNA) mediated by Drosha in the nucleus and from pre-miRNAs to mature miRNAs mediated by Dicer in the cytoplasm. Various routes of miRNA maturation that are tightly regulated by signaling cascades and specific to an individual or a subclass of miRNAs have been recently identified. Here, we review the current findings in signaling-mediated miRNA processing as well as their potential clinical relevance in cancer. Cancer Res; 75(5); 1–9. ©2014 AACR.

Chronic inflammation is a hallmark of many cancers, yet the pathogenic mechanisms that distinguish cancer-associated inflammation from benign persistent inflammation are still mainly unclear. Here, we report that the protein kinase ERK5 controls the expression of a specific subset of inflammatory mediators in the mouse epidermis, which triggers the recruitment of inflammatory cells needed to support skin carcinogenesis. Accordingly, inactivation of ERK5 in keratinocytes prevents inflammation-driven tumorigenesis in this model. In addition, we found that anti-ERK5 therapy cooperates synergistically with existing antimitotic regimens, enabling efficacy of subtherapeutic doses. Collectively, our findings identified ERK5 as a mediator of cancer-associated inflammation in the setting of epidermal carcinogenesis. Considering that ERK5 is expressed in almost all tumor types, our findings suggest that targeting tumor-associated inflammation via anti-ERK5 therapy may have broad implications for the treatment of human tumors. Cancer Res; 75(4); 1–12. ©2015 AACR.

TP53 gene mutation is associated with poor prognosis in breast cancer, but additional biomarkers that can further refine the impact of the p53 pathway are needed to achieve clinical utility. In this study, we evaluated a role for the HDMX-S/FL ratio as one such biomarker, based on its association with other suppressor mutations that confer worse prognosis in sarcomas, another type of cancer that is surveilled by p53. We found that HDMX-S/FL ratio interacted with p53 mutational status to significantly improve prognostic capability in patients with breast cancer. This biomarker pair offered prognostic utility that was comparable with a microarray-based prognostic assay. Unexpectedly, the utility tracked independently of DNA-damaging treatments and instead with different tumor metastasis potential. Finally, we obtained evidence that this biomarker pair might identify patients who could benefit from anti-HDM2 strategies to impede metastatic progression. Taken together, our work offers a p53 pathway marker, which both refines our understanding of the impact of p53 activity on prognosis and harbors potential utility as a clinical tool. Cancer Res; 75(4); 1–11. ©2015 AACR.

The hallmark of most cancer cells is the metabolic shift from mitochondrial to glycolytic metabolism for adapting to the surrounding environment. Although epigenetic modification is intimately linked to cancer, the molecular mechanism, by which epigenetic factors regulate cancer metabolism, is poorly understood. Here, we show that lysine-specific demethylase-1 (LSD1, KDM1A) has an essential role in maintaining the metabolic shift in human hepatocellular carcinoma cells. Inhibition of LSD1 reduced glucose uptake and glycolytic activity, with a concurrent activation of mitochondrial respiration. These metabolic changes coexisted with the inactivation of the hypoxia-inducible factor HIF1α, resulting in a decreased expression of GLUT1 and glycolytic enzymes. In contrast, during LSD1 inhibition, a set of mitochondrial metabolism genes was activated with the concomitant increase of methylated histone H3 at lysine 4 in the promoter regions. Consistently, both LSD1 and GLUT1 were significantly overexpressed in carcinoma tissues. These findings demonstrate the epigenetic plasticity of cancer cell metabolism, which involves an LSD1-mediated mechanism. Cancer Res; 75(7); 1–12. ©2015 AACR.

The hallmark of most cancer cells is the metabolic shift from mitochondrial to glycolytic metabolism for adapting to the surrounding environment. Although epigenetic modification is intimately linked to cancer, the molecular mechanism, by which epigenetic factors regulate cancer metabolism, is poorly understood. Here, we show that lysine specific demethylase-1 (LSD1, KDM1A) has an essential role in maintaining the metabolic shift in human hepatocellular carcinoma (HCC) cells. Inhibition of LSD1 reduced glucose uptake and glycolytic activity, with a concurrent activation of mitochondrial respiration. These metabolic changes coexisted with the inactivation of the hypoxia-inducible factor HIF-1α, resulting in a decreased expression of GLUT1 and glycolytic enzymes. By contrast, during LSD1 inhibition, a set of mitochondrial metabolism genes was activated with the concomitant increase of methylated histone H3 at lysine 4 in the promoter regions. Consistently, both LSD1 and GLUT1 were significantly overexpressed in carcinoma tissues. These findings demonstrate the epigenetic plasticity of cancer cell metabolism, which involves an LSD1-mediated mechanism.