Although obesity is one of the strongest risk factors for esophageal adenocarcinoma, the molecular mechanisms underlying this association remain unclear. We recently identified four esophageal adenocarcinoma–specific master regulator transcription factors (MRTF) ELF3, KLF5, GATA6, and EHF. In this study, gene-set enrichment analysis of both esophageal adenocarcinoma patient samples and cell line models unbiasedly underscores fatty acid synthesis as the central pathway downstream of three MRTFs (ELF3, KLF5, GATA6). Further characterizations unexpectedly identified a transcriptional feedback loop between MRTF and fatty acid synthesis, which mutually activated each other through the nuclear receptor, PPARG. MRTFs cooperatively promoted PPARG transcription by directly regulating its promoter and a distal esophageal adenocarcinoma–specific enhancer, leading to PPARG overexpression in esophageal adenocarcinoma. PPARG was also elevated in Barrett’s esophagus, a recognized precursor to esophageal adenocarcinoma, implying that PPARG might play a role in the intestinal metaplasia of esophageal squamous epithelium. Upregulation of PPARG increased de novo synthesis of fatty acids, phospholipids, and sphingolipids as revealed by mass spectrometry–based lipidomics. Moreover, ChIP-seq, 4C-seq, and a high-fat diet murine model together characterized a novel, noncanonical, and cancer-specific function of PPARG in esophageal adenocarcinoma. PPARG directly regulated the ELF3 super-enhancer, subsequently activating the transcription of other MRTFs through an interconnected regulatory circuitry. Together, elucidation of this novel transcriptional feedback loop of MRTF/PPARG/fatty acid synthesis advances our understanding of the mechanistic foundation for epigenomic dysregulation and metabolic alterations in esophageal adenocarcinoma. More importantly, this work identifies a potential avenue for prevention and early intervention of esophageal adenocarcinoma by blocking this feedback loop. Significance: These findings elucidate a transcriptional feedback loop linking epigenomic dysregulation and metabolic alterations in esophageal adenocarcinoma, indicating that blocking this feedback loop could be a potential therapeutic strategy in high-risk individuals.

Colorectal cancer (CRC) is a highly malignant tumor associated with poor prognosis, yet the molecular mechanisms are not fully understood. In this study, we showed that LYAR, a nucleolar protein, is expressed at a higher level in CRC tissue than in adjacent normal tissue and that LYAR expression is closely associated with distant CRC metastasis. LYAR not only significantly promotes the migration and invasion of CRC cells in vitro, but knockdown (KD) of LYAR in CRC cells also inhibits xenograft tumor metastasis in vivo. Microarray analysis of LYAR KD cells combined with a chromatin immunoprecipitation (ChIP) assay, gene reporter assay, and rescue experiment indicated that FSCN1 (encoding fascin actin‐bundling protein 1 (Fascin‐1)) serves as a novel key regulator of LYAR‐promoted migration and invasion of CRC cells. Knockdown of FSCN1 significantly inhibits subcutaneous tumorigenesis of CRC cells and leads to the downregulation of FASN and SCD, genes encoding key enzymes in fatty acid synthesis. In summary, this study reveals a novel mechanism by which LYAR promotes tumor cell migration and invasion by upregulating FSCN1 expression and affecting fatty acid metabolism in CRC.

Increasing evidence suggests that liver cancer stem cells (LCSCs) are the cellular determinants that promote tumor recurrence and metastases. Aberrantly expressed miRNAs were identified in LCSCs and found to play a significant role in modulating biological characteristics of LCSCs. In this study, we implemented miRNA microarrays in CD133⁺ LCSCs and found miR-101 expression was downregulated. Increasing miR-101 expression repressed the metastasis and tumorigenic potential in LCSCs. Further investigations showed that ANXA2 was a novel target of miR-101. And we revealed that ANXA2 plays a critical role in acceleration of cell cycle and enhancing the migration and invasion abilities of LCSCs. Elevated ANXA2 increased activation of extracellular signal-regulated kinase (ERK) which regulated SOX2 and cell cycle-related kinases. Moreover, ERK phosphorylation inhibited the expression of early growth response 1 (EGR1) which in turn restrained the transcription of miR-101. In vivo experiments, overexpression of miR-101 produced potent inhibitory effects on the growth of LCSCs xenograft tumors as well as ANXA2 knockdown. Taken together, our findings suggest a novel regulatory loop miR-101/ANXA2/EGR1 in LCSCs and may serve as potential therapeutic targets in liver cancer.

Background: Increasing evidence suggests that FBXW7 has a high frequency of mutations in esophageal squamous cell carcinoma (ESCC). However, the function of FBXW7, especially the mutations, is not clear. This study was designed to investigate the functional significance of FBXW7 loss of function and underlying mechanism in ESCC. Methods: Immunofluorescence was applied to clarify the localization and main isoform of FBXW7 in ESCC cells. Sanger sequencing were performed to explore mutations of FBXW7 in ESCC tissues. Proliferation, colony, invasion and migration assays were performed to examine the functional roles of FBXW7 in ESCC cells in vitro and in vivo. Real-time RT-PCR, immunoblotting, GST-pulldown, LC–MS/MS and co-immunoprecipitation assay were used to explore the molecular mechanism underlying the actions of FBXW7 functional inactivation in ESCC cells. Immunohistochemical staining were used to explore the expression of FBXW7 and MAP4 in ESCC tissues. Results: The main FBXW7 isoform in ESCC cells was the β transcript in the cytoplasm. Functional inactivation of FBXW7 led to activation of the MAPK signaling pathway and upregulation of the downstream MMP3 and VEGFA, which enhanced tumor proliferation cell invasion and migration. Among the five mutation forms screened, S327X (X means truncated mutation) had an effect similar to the FBXW7 deficiency and led to the inactivation of FBXW7 in ESCC cells. Three other point mutations, S382F, D400N and R425C, attenuated but did not eliminate FBXW7 function. The other truncating mutation, S598X, which was located outside of the WD40 domain, revealed a tiny attenuation of FBXW7 in ESCC cells. Notably, MAP4 was identified as a potential target of FBXW7. The threonine T521 of MAP4, which was phosphorylated by CHEK1, played a key role in the FBXW7-related degradation system. Immunohistochemical staining indicated that FBXW7 loss of function was associated with tumor stage and shorter survival of patients with ESCC. Univariate and multivariate Cox proportional hazards regression analyses showed that high FBXW7 and low MAP4 was an independent prognostic indicator and prospective longer survival. Moreover, a combination regimen that included MK-8353 to inhibit the phosphorylation of ERK and bevacizumab to inhibit VEGFA produced potent inhibitory effects on the growth of FBXW7 inactivation xenograft tumors in vivo. Conclusions: This study provided evidence that FBXW7 loss of function promoted ESCC via MAP4 overexpression and ERK phosphorylation, and this novel FBXW7/MAP4/ERK axis may be an efficient target for ESCC treatment.