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Abstract Background Increasing evidence suggests that aberrant methylation is involved in 5-fluorouracil (5-FU) resistance in gastric cancer (GC). Our previous work has identified that Methyl-CpG binding protein 2 (MeCP2) promotes GC progression by binding to the methylation sites of promoter regions of specific genes to affect the downstream signaling pathways. However, the function and molecular mechanisms of MeCP2 in GC 5-FU resistance remain unclear. Methods We detected the expression of MeCP2 in 5-FU-resistant GC cells and examined cell behaviors when MeCP2 was silenced. The molecular mechanisms were explored through chromatin immunoprecipitation (ChIP)-qRT-PCR, luciferase reporter assay, clinical tissue samples analysis, and in vivo tumorigenicity assay. Results MeCP2 was up-regulated in 5-FU-resistant GC cells. Knockdown of MeCP2 enhanced the sensitivity of the cells to 5-FU. Moreover, MeCP2 promoted NOX4 transcription in the cells by binding to the promoter of NOX4. Silencing NOX4 rescued the inductive effect of MeCP2 overexpression on 5-FU sensitivity of GC cells and reduced the expression of NOX4 and PKM2 in MeCP2 overexpressed 5-FU-resistant GC cells. In addition, our in vivo experiments demonstrated that MeCP2 knockdown enhanced 5-FU sensitivity in tumors. Conclusion MeCP2 confers 5-FU resistance in GC cells via upregulating the NOX4/PKM2 pathway, which may lead to a promising therapeutic strategy for GC.

Abstract Background UBTF is an HMGB-box DNA binding protein and a necessary Pol I/Pol II basal transcription factor. It has been found that UBTF involves in carcinogenesis and progression of a few cancers. Nevertheless, the the biological function and potential molecular mechanism of UBTF in melanoma are still not clear and need to be clarified. Methods UBTF and GIT1 expressions in melanoma specimens and cell lines were examined by quantitative real-time PCR (qRT-PCR) and Western blot. MTT and colony formation assays were used to investigate the effects of UBTF and GIT1 on melanoma cell proliferation. Cell cycle and apoptosis assays were detected by flow cytometry. Tumor formation assay was used to analyze the effect of UBTF on melanoma growth. Bioinformatics predicting, chromatin immunoprecipitation (ChIP)-qRT-PCR and reporter gene assay were fulfilled for verifing GIT1 as UBTF targeting gene. Results Here we reported that UBTF mRNA and protein expressions were upregulated in primary melanoma specimens and cell lines. UBTF overexpression facilitated melanoma cell proliferation and cell cycle progression and restrained. Silencing UBTF suppressed cell multiplication, cell cycle progression and tumor growth, and promoted apoptosis. UBTF expression was positively related with GIT1 expression in human melanoma tissues. It was verified that UBTF promoted GIT1 transcription in melanoma cells through binding to the promoter region of GIT1. Furthermore, GIT1 overexpression promoted melanoma cell growth and suppressed apoptosis. Knockdown of GIT1 inhibited cell multiplication and induced apoptosis. Overexpression of GIT1 eliminated the effects of silencing UBTF on melanoma cells. Importantly, UBTF activated MEK1/2-ERK1/2 signalling pathways by upregulating GIT1 expression. Conclusions Our study demonstrates that UBTF promotes melanoma cell proliferation and cell cycle progression by promoting GIT1 transcription, thereby activating MEK1/2-ERK1/2 signalling pathways. The findings indicate that UBTF plays a crucial function in melanoma and may be a potential therapeutic target for the treatment of this disease.

Background: Increasing evidence suggests that aberrant methylation is involved in 5-fluorouracil (5-FU) resistance in gastric cancer (GC). Our previous work has identified that Methyl-CpG binding protein 2 (MeCP2) promotes GC progression by binding to the methylation sites of promoter regions of specific genes to affect the downstream signaling pathways. However, the function and molecular mechanisms of MeCP2 in GC 5-FU resistance remain unclear. Methods: We detected the expression of MeCP2 in 5-FU-resistant GC cells and examined cell behaviors when MeCP2 was silenced. The molecular mechanisms were explored through chromatin immunoprecipitation (ChIP)-qRT-PCR, luciferase reporter assay, clinical tissue samples analysis, and in vivo tumorigenicity assay. Results: MeCP2 was up-regulated in 5-FU-resistant GC cells. Knockdown of MeCP2 enhanced the sensitivity of the cells to 5-FU. Moreover, MeCP2 promoted NOX4 transcription in the cells by binding to the promoter of NOX4. Silencing NOX4 rescued the inductive effect of MeCP2 overexpression on 5-FU sensitivity of GC cells and reduced the expression of NOX4 and PKM2 in MeCP2 overexpressed 5-FU-resistant GC cells. In addition, our in vivo experiments demonstrated that MeCP2 knockdown enhanced 5-FU sensitivity in tumors. Conclusion: MeCP2 confers 5-FU resistance in GC cells via upregulating the NOX4/PKM2 pathway, which may lead to a promising therapeutic strategy for GC. [ABSTRACT FROM AUTHOR]

Background: UBTF is an HMGB-box DNA binding protein and a necessary Pol I/Pol II basal transcription factor. It has been found that UBTF involves in carcinogenesis and progression of a few cancers. Nevertheless, the the biological function and potential molecular mechanism of UBTF in melanoma are still not clear and need to be clarified. Methods: UBTF and GIT1 expressions in melanoma specimens and cell lines were examined by quantitative real-time PCR (qRT-PCR) and Western blot. MTT and colony formation assays were used to investigate the effects of UBTF and GIT1 on melanoma cell proliferation. Cell cycle and apoptosis assays were detected by flow cytometry. Tumor formation assay was used to analyze the effect of UBTF on melanoma growth. Bioinformatics predicting, chromatin immunoprecipitation (ChIP)-qRT-PCR and reporter gene assay were fulfilled for verifing GIT1 as UBTF targeting gene. Results: Here we reported that UBTF mRNA and protein expressions were upregulated in primary melanoma specimens and cell lines. UBTF overexpression facilitated melanoma cell proliferation and cell cycle progression and restrained. Silencing UBTF suppressed cell multiplication, cell cycle progression and tumor growth, and promoted apoptosis. UBTF expression was positively related with GIT1 expression in human melanoma tissues. It was verified that UBTF promoted GIT1 transcription in melanoma cells through binding to the promoter region of GIT1. Furthermore, GIT1 overexpression promoted melanoma cell growth and suppressed apoptosis. Knockdown of GIT1 inhibited cell multiplication and induced apoptosis. Overexpression of GIT1 eliminated the effects of silencing UBTF on melanoma cells. Importantly, UBTF activated MEK1/2-ERK1/2 signalling pathways by upregulating GIT1 expression. Conclusions: Our study demonstrates that UBTF promotes melanoma cell proliferation and cell cycle progression by promoting GIT1 transcription, thereby activating MEK1/2-ERK1/2 signalling pathways. The findings indicate that UBTF plays a crucial function in melanoma and may be a potential therapeutic target for the treatment of this disease. [ABSTRACT FROM AUTHOR]