Mis-regulated RNA modifications promote the processing and translation of oncogenic mRNAs to facilitate cancer progression, while the molecular mechanisms remain unclear. Here we reveal that tRNA m7G methyltransferase complex proteins METTL1 and WDR4 are significantly up-regulated in esophageal squamous cell carcinoma (ESCC) tissues and associated with poor ESCC prognosis. In addition, METTL1 and WDR4 promote ESCC progression via the tRNA m7G methyltransferase activity in vitro and in vivo. Mechanistically, METTL1 or WDR4 knockdown leads to decreased expression of m7G-modified tRNAs and reduces the translation of a subset of oncogenic transcripts enriched in RPTOR/ULK1/autophagy pathway. Furthermore, ESCC models using Mettl1 conditional knockout and knockin mice uncover the essential function of METTL1 in promoting ESCC tumorigenesis in vivo. Our study demonstrates the important oncogenic function of mis-regulated tRNA m7G modification in ESCC, and suggest that targeting METTL1 and its downstream signaling axis could be a promising therapeutic target for ESCC treatment.

Esophageal cancer is a lethal malignancy with a high mortality rate, while the molecular mechanisms underlying esophageal cancer pathogenesis are still poorly understood. Here, we found that the N6-methyladenosine (m 6 A) methyltransferase-like 3 (METTL3) is significantly upregulated in esophageal squamous cell carcinoma (ESCC) and associated with poor patient prognosis. Depletion of METTL3 results in decreased ESCC growth and progression in vitro and in vivo. We further established ESCC initiation and progression models using Mettl3 conditional knockout mouse and revealed that METTL3-mediated m 6 A modification promotes ESCC initiation and progression in vivo. Moreover, using METTL3 overexpression ESCC cell model andMettl3 conditional knockin mouse model, we demonstrated the critical function of METTL3 in promoting ESCC tumorigenesis in vitro and in vivo. Mechanistically, METTL3-catalyzed m 6 A modification promotes NOTCH1 expression and the activation of the Notch signaling pathway. Forced activation of Notch signaling pathway successfully rescues the growth, migration, and invasion capacities of METTL3-depleted ESCC cells. Our data uncovered important mechanistical insights underlying ESCC tumorigenesis and provided molecular basis for the development of novel strategies for ESCC diagnosis and treatment.

Alcohol is a well-established cause of esophageal carcinoma, but its effect on survival is little known and contradictory. To clarify whether drinking is an independent predictor of survival in esophageal carcinoma, 2151 Chinese patients, receiving surgical resection from January 1997 to December 2008, were followed until March 2014. Cox proportional hazards analysis was applied to evaluate the prognostic effect of alcohol consumption. The median follow-up was 64 months. The median overall survival (OS; 42 months) and disease-free survival (DFS; 33 months) for never-drinkers were significantly higher than ever-drinkers (27 and 22 months, respectively). In the multivariate Cox model that was adjusted for age, weight loss, stage according to criteria set by the American Joint Committee on Cancer, radicality of surgery, adjuvant treatment, smoking status, and gender, the hazard ratios of ever-drinking were 1.22 (1.06–1.41, P = 0.005) on OS, and 1.16 (1.01–1.34, P = 0.037) on DFS. The hazardous effect on OS and DFS of drinking grew statistically significantly in a dose-dependent manner with increasing amount of alcohol consumption per day (both P-value for trend < 0.05). The predictive effect of drinking on OS (P = 0.596) or DFS (P = 0.207) was not significant in the subgroup with esophageal adenocarcinoma (n = 195). The current study revealed that the survival is shortened, of those patients who consume alcohol before diagnosis of esophageal squamous cell carcinoma, which are not attributable to differences in stage, smoking status, and gender. Alcohol control should be emphasized to reduce mortality of esophageal carcinoma, and further outcome studies should include alcohol as a potential prognosticator.

BackgroundDysregulation of the cell cycle has been implicated in esophageal squamous cell carcinoma (ESCC) progression. This study aimed to evaluate the role of miR-424 in cell cycle regulation and ESCC proliferation.MethodsThe role of miR-424 in cell proliferation was evaluated in vitro and in vivo. Transcriptional activation of miR-424 was determined using chromatin immunoprecipitation, and binding of miR-424 to targets was verified using miRNA ribonucleoprotein complex immunoprecipitation.FindingsmiR-424 was upregulated and correlated with poor survival in ESCC patients. Repression or overexpression of miR-424 respectively decreased or increased ESCC cell proliferation in vitro and in vivo. miR-424 expression is transcriptionally regulated by E2F1 and increased during G1/S transition. Knockdown or overexpression of miR-424 respectively inhibited or promoted both G1/S and G2/M cell cycle transitions in ESCC cells, and these effects were mediated by two newly identified miR-424 targets, PRKCD and WEE1, respectively. Consequently, elevation of PRKCD by miR-424 knockdown led to enhanced stability of the p21Cip1 protein via increased activation of PRKCD and downstream p38 MAPK and JNK signaling to block CDK2 activation and G1/S transition, while elevated WEE1 maintained CDC2 in an inactive state to block G2/M transition. However, circLARP4 could sponge the binding of miR-424 to PRKCD, thus compromising the regulation of G1/S progression by miR-424.InterpretationmiR-424 coordinates a previously unknown, multilayered regulation of ESCC cell cycle progression to promote ESCC proliferation, and may be used as a novel prognostic marker and an effective therapeutic target for ESCCs.FundNational Natural Science Foundation of China.

The tumor microenvironment (TME) of esophageal squamous cell carcinoma (ESCC) impacts tumor progression but is poorly understood. We obtained tumor tissues from 279 patients after esophagectomy and characterized the TME in intraepithelial and stromal regions using multiplex fluorescent immunohistochemistry (mfIHC). A heterogeneous immune population infiltrating tumor and the uninvolved esophageal tissue were observed. The infiltration of intraepithelial programmed death ligand 1 (PD-L1)positive tumor-associated macrophages (TAMs) and stromal granzyme B + activated cytotoxic T cells (aCTLs) correlated with both prolonged overall survival (OS) and disease-free survival (DFS). The intraepithelial memory T cell infiltration predicted longer OS, while intraepithelial and stromal regulatory T cell (Treg) infiltration was associated with shortened OS and DFS, respectively. Multivariate models combining immune infiltrates and clinicopathological factors outperformed tumor-node-metastasis (TNM) stage in predicting OS and DFS at 3 and 5 years. The infiltration of Treg inversely correlated with that of the antitumor effectors including CTLs, aCTLs, and natural killer (NK) cells. Intraepithelial memory T cell infiltration also negatively correlated with PD-L1 expression. In spatial analysis, intraepithelial dendritic cell (DC)-memory T cell engagement increased in high PD-L1 + TAM infiltration group. The characterization of the TME revealed a complex interplay between immune populations and may be employed to stratify patient for prognosis prediction and immunotherapy.