Krüppel-like factor 4 (KLF4) is highly expressed in epithelial tissues such as the gut and skin. However, the role of KLF4 in human gastric cancer development and progression is unknown. Here we show that KLF4 protein expression was decreased or lost in primary tumors and, in particular, lymph node metastases when compared with that in normal gastric mucosa. Moreover, loss of KLF4 expression in the primary tumors was significantly associated with poor survival, and also an independent prognostic marker in a multivariate analysis. Consistently, most human gastric cancer cell lines exhibited loss of or a substantial decrease in KLF4 expression at both RNA and protein levels. Enforced restoration of KLF4 expression resulted in marked cell growth inhibition in vitro and significantly attenuated tumor growth and total abrogation of metastasis in an orthotopic animal model of gastric cancer. Mechanism studies indicated that promoter hypermethylation and hemizygous deletion contributed to the down-regulation of KLF4 expression and the induction of apoptosis contributed to the antitumor activity of KLF4. Collectively, our data provide first clinical and casual evidence and potential mechanism that the alteration of KLF4 expression plays a critical role in gastric cancer development and progression. (Cancer Res 2005; 65(7): 2746-54)

BackgroundEmerging evidence has shown that dysregulation function of long non-coding RNAs (lncRNAs) implicated in gastric cancer (GC). However, the role of the differentially expressed lncRNAs in GC has not fully explained.MethodsLncRNA expression profiles were determined by lncRNA microarray in five pairs of normal and GC tissues, further validated in another 75 paired tissues by quantitative real-time PCR (qRT-PCR). Overexpression of lncRNA MT1JP was conducted to assess the effect of MT1JP in vitro and in vivo. The biological functions were demonstrated by luciferase reporter assay, western blotting and rescue experiments.ResultsLncRNA MT1JP was significantly lower in GC tissues than adjacent normal tissues, and higher MT1JP was remarkably related to lymph node metastasis and advance stage. Besides, GC patients with higher MT1JP expression had a well survival. Functionally, overexpression of lncRNA MT1JP inhibited cell proliferation, migration, invasion and promoted cell apoptosis in vitro, and inhibited tumor growth and metastasis in vivo. Functional analysis showed that lncRNA MT1JP regulated FBXW7 expression by competitively binding to miR-92a-3p. MiR-92a-3p and down-regulated FBXW7 reversed cell phenotypes caused by lncRNA MT1JP by rescue analysis.ConclusionMT1JP, a down-regulated lncRNA in GC, was associated with malignant tumor phenotypes and survival of GC. MT1JP regulated the progression of GC by functioning as a competing endogenous RNA (ceRNA) to competitively bind to miR-92a-3p and regulate FBXW7 expression. Our study provided new insight into the post-transcriptional regulation mechanism of lncRNA MT1JP, and suggested that MT1JP may act as a potential therapeutic target and prognosis biomarker for GC.Electronic supplementary materialThe online version of this article (10.1186/s12943-018-0829-6) contains supplementary material, which is available to authorized users.

Glucose-regulated protein 78 (GRP78) has been implicated in the protection of tumor cells from cytotoxic damage and apoptosis and thus assists cells in survival under oxygen-deprivation and nutrient-stress conditions. However, its expression and potential role in gastric cancer development and progression have not been reported. In the present study, we determined the level of GRP78 expression in the primary tumor in 86 cases of resected gastric cancer by using immunohistochemistry and analyzed the relationships between GRP78 and clinicopathological characteristics. We found that GRP78 was overexpressed in the tumor specimens when compared with the expression in adjacent tumor-free gastric mucosa. Furthermore, the level of GRP78 expression in both primary tumors and metastatic lymph nodes was inversely correlated with patient survival. Overexpression of GRP78 was directly correlated with Sp1 expression and increased lymph node metastasis. Knocking down GRP78 expression inhibited tumor cell invasion in vitro and growth and metastasis in a xenograft nude mouse model. Therefore, our data imply that dysregulated expression of GRP78 may contribute to the development and progression of gastric cancer.

The biological and clinical behaviors of cancer are affected by multiple molecular pathways that are under the control of transcription factors. Improved understanding of how transcription factors affect cancer biology may lead to improved ability to predict clinical outcome and discovery of novel therapeutic strategies. We evaluated the relationship between Sp1 and vascular endothelial growth factor (VEGF) expression, as well as their effect on survival in 86 cases of resected human gastric cancer. The degree of VEGF expression correlated highly with Sp1 expression (P < 0.01). Patients with high Sp1 expression were 98 times more likely to have high VEGF expression compared with those with negative Sp1 expression. Clinically, negative or weak Sp1 expression was associated with early stage (IA) in gastric cancer. Strong Sp1 expression was more frequently observed among patients with stage IB-IV disease (P ‫؍‬ 0.035). Similarly, whereas strong Sp1 expression was uncommonly observed among patients with N0 or N1 disease (19 and 16%), N2/N3 gastric cancer was associated with strong Sp1 expression (48%; P ‫؍‬ 0.034). Strong Sp1 expression was also associated with inferior survival. The median survival duration in patients who had a tumor with a negative, weak, and strong Sp1 expression was 44, 38, and 8 months (P ‫؍‬ 0.0075), respectively, whereas patients with strong VEGF expression had a shorter survival duration; the difference was not statistically significant. When Sp1 and VEGF expression, stage, completeness of resection, histology, and patient age were entered in a Cox proportional hazards model, strong Sp1 expression (P ‫؍‬ 0.021) and an advanced disease stage (P < 0.001) were independently prognostic of poor survival. Given the importance of Sp1 in the expression of VEGF, our data suggest that dysregulated Sp1 expression and activation play important roles in VEGF overexpression and, thus, gastric cancer development and progression.

We recently showed that FoxM1 is overexpressed in human glioblastomas and that forced FoxM1B expression in anaplastic astrocytoma cells leads to the formation of highly invasive glioblastoma multiforme (GBM) in nude mice. However, the molecular mechanisms by which FoxM1 enhances glioma invasion are unknown. In this study, we found that FoxM1 overexpression increased matrix metalloproteinase (MMP)-2 expression in glioma cells, whereas blockade of FoxM1 expression suppressed MMP-2 expression. Transfection of FoxM1 into glioma cells directly activated the MMP-2 promoter, whereas inhibition of FoxM1 expression by FoxM1-siRNA suppressed its activation. We identified a FoxM1-binding site in the MMP-2 promoter and demonstrated that FoxM1 protein bound directly to it. Mutation of this FoxM1-binding site significantly attenuated MMP-2 promoter activity. Furthermore, FoxM1 overexpression increased the invasiveness of glioma cells, whereas inhibition of FoxM1 expression suppressed the invasiveness of GBM cells. Inhibition of MMP-2 by a specific MMP-2 inhibitor reversed the invasive phenotype of glioma cells overexpressing FoxM1. Finally, immunohistochemical analysis of 45 human GBM specimens showed a significant correlation between FoxM1 overexpression and elevated MMP-2 expression. Collectively, these findings provide evidence that FoxM1 contributes to glioma progression by enhancing MMP-2 gene transcription and thus tumor-cell invasion.

Purpose: Angiogenic behavior is a critical aspect of cancer biology and subject to regulation by multiple molecular pathways. Because the signal transducer and activator of transcription 3 (Stat3) transcription factor regulates multiple genes important to angiogenesis, we sought to determine whether Stat3 expression is related to vascular endothelial growth factor (VEGF) expression and microvessel density (MVD) in gastric cancer and whether these factors predict survival in gastric cancer patients. Experimental Design: The expression of Stat3 and VEGF was determined by immunohistochemistry using archival tissues from 86 cases of resected human gastric cancer and confirmed by Western blot analysis. Angiogenic phenotype was determined by CD34 staining and microvessel counting. Results: Stat3 expression correlated with VEGF expression and MVD. In univariate survival analyses, Stat3 expression (P = 0.013) and MVD (P = 0.036) were associated with inferior survival. However, when Stat3 expression, VEGF expression, MVD, stage, completeness of resection, Lauren's histologic classification, and age were entered into a Cox proportional hazards model, only strong Stat3 expression (P = 0.049) and advanced stage (P &lt; 0.01) were independently prognostic of poor survival. Furthermore, genetically enforced alterations of activated Stat3 expression led to altered VEGF expression and angiogenic potential in human gastric cancer cells. Conclusion: Dysregulated Stat3 activation may play an important role in VEGF overexpression and elevated angiogenic phenotype in gastric cancer and contribute to gastric cancer development and progression.

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Interactions between WD40 repeat domain protein 5 (WDR5) and its various partners such as mixed lineage leukemia (MLL) and c-MYC are essential for sustaining oncogenesis in human cancers. However, inhibitors that block protein-protein interactions (PPIs) between WDR5 and its binding partners exhibit modest cancer cell killing effects and lack in vivo efficacy. Here, we present pharmacological degradation of WDR5 as a promising therapeutic strategy for treating WDR5-dependent tumors and report two high-resolution crystal structures of WDR5degrader-E3 ligase ternary complexes. We identified an effective WDR5 degrader via structure-based design and demonstrated its in vitro and in vivo antitumor activities. On the basis of the crystal structure of an initial WDR5 degrader in complex with WDR5 and the E3 ligase von Hippel-Lindau (VHL), we designed a WDR5 degrader, MS67, and demonstrated the high cooperativity of MS67 binding to WDR5 and VHL by another ternary complex structure and biophysical characterization. MS67 potently and selectively depleted WDR5 and was more effective than WDR5 PPI inhibitors in suppressing transcription of WDR5-regulated genes, decreasing the chromatin-bound fraction of MLL complex components and c-MYC, and inhibiting the proliferation of cancer cells. In addition, MS67 suppressed malignant growth of MLL-rearranged acute myeloid leukemia patient cells in vitro and in vivo and was well tolerated in vivo. Collectively, our results demonstrate that structure-based design can be an effective strategy to identify highly active degraders and suggest that pharmacological degradation of WDR5 might be a promising treatment for WDR5-dependent cancers.