RESUMO
Resistance to chemotherapeutic drugs leads to a poor prognosis in gastric cancer (GC). The present study aimed to assess the association between pituitary homeobox paired homeodomain transcription 1 (PITX1) expression and the sensitivity of GC cells to the chemotherapeutic drugs 5-fluorouracil (5-FU) and cisplatin (CDDP). In the present study, the gastric cancer cell lines GES-1, AGS, BGC-823, MCG-803 and SGC-7901 were used. The expression of PITX1 was determined via reverse transcription-quantitative polymerase chain reaction in GC cell lines. AGS and BGC-823 cells, which exhibit a decreased PITX1 expression, were transfected with a PITX1 cDNA construct and its control vector. MCG-803 and SGC-7901 cells, which exhibit an increased PITX1 expression, were transfected with siRNA against PITX1 and its control scramble sequence. A Cell Counting kit-8 assay was performed to determine the impact of PITX1 expression on the sensitivity of GC cells to 5-FU and CDDP. The Cancer Genome Atlas database was used to analyze the expression of PITX1 with GC prognosis in the Asian population and to assess the potential mechanism of PITX1 in 5-FU and CDDP resistance. The results revealed that the overexpression of PIXT1 increased the sensitivity of GC cells to 5-FU/CDDP. The combination of 5-FU/CDDP and PITX1 overexpression also reduced the proliferation of GC cells. Additionally, PIXT1 knockdown decreased the sensitivity of GC cells to 5-FU/CDDP. TCGA data revealed that a lower expression of PITX1 is exhibited in Asian GC patients than in normal individuals. GC patients with a lower expression of PITX1 had a poor prognosis. The expression of PITX1 affected the sensitivity of GC cells to 5-FU/CDDP, indicating that PITX1 may increase the efficacy of treatment in GC patients.
RESUMO
OBJECTIVES: Long non-coding RNAs (LncRNAs) play an important role in hepatocellular carcinoma development, however, as a crucial driver of hepatocellular carcinoma (HCC) metastasis, their functions in tumour metastasis remain largely unknown. MATERIALS AND METHODS: The lncRNA TRERNA1 expression levels were detected in HCC by quantitative real-time PCR (qPCR). The function of TRERNA1 was examined by wound-healing assays, transwell assays and tail vein injection experiments. The potential regulatory mechanisms of TRERNA1 on its target genes were explored by ChIP, RIP, IP and WB assays. RESULTS: Elevated TRERNA1 levels promoted HCC cell migration and invasion in vitro and in vivo. TRERNA1 recruited EHMT2 to dimethylate H3K9 in the CDH1 promoter region. Furthermore, EHMT2 bound to SNAI1 to suppress CDH1 expression in HCC cells. After inhibiting TRERNA1, the expression level of CDH1 was restored and was involved in the regulation of the EHMT2/SNAI1 complex. The level of TRERNA1 was positively correlated with tumour metastasis and was negatively correlated with the expression of CDH1 in HCC tissues. CONCLUSIONS: For the first time, the current study reveals that TRERNA1 promotes cell metastasis and the invasion of HCC via the recruitment of EHMT2 and/or the EHMT2/SNAI1 complex to suppress CDH1. These data identify a novel mechanism that regulates TRERNA1 in metastatic HCC and provides a potential targeted therapy for HCC patients.
Assuntos
Antígenos CD/genética , Caderinas/genética , Carcinoma Hepatocelular/genética , Antígenos de Histocompatibilidade/genética , Histona-Lisina N-Metiltransferase/genética , Neoplasias Hepáticas/genética , Regiões Promotoras Genéticas/genética , RNA Longo não Codificante/genética , Fatores de Transcrição da Família Snail/genética , Animais , Carcinoma Hepatocelular/fisiopatologia , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Transição Epitelial-Mesenquimal/genética , Regulação Neoplásica da Expressão Gênica/genética , Células Hep G2 , Humanos , Neoplasias Hepáticas/patologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Invasividade Neoplásica/genética , Invasividade Neoplásica/patologia , Metástase Neoplásica/genética , Metástase Neoplásica/patologia , Interferência de RNA/fisiologiaRESUMO
DNA methyltransferase 3A (DNMT3A) has been recognised as a key element of epigenetic regulation in normal development, and the aberrant regulation of DNMT3A is implicated in multiple types of cancers, especially haematological malignancies. However, its clinical significance and detailed functional role in solid tumours remain unknown, although abnormal expression has gained widespread attention in these cancers. Here, we show that DNMT3A isoform b (DNMT3Ab), a member of the DNMT3A isoform family, is critical for directing epithelial-mesenchymal transition (EMT)-associated metastasis in gastric cancer (GC). DNMT3Ab is positively linked to tumour-node-metastasis (TNM) stage, lymph node metastasis and poor prognosis in GC patients. Overexpression of DNMT3Ab promotes GC cell migration and invasion as well as EMT through repression of E-cadherin. Meanwhile, DNMT3Ab promotes lung metastasis of GC in vivo. Mechanistic studies indicate that DNMT3Ab mediates the epigenetic inaction of the E-cadherin gene via DNA hypermethylation and histone modifications of H3K9me2 and H3K27me3. Depletion of DNMT3Ab effectively restores the expression of E-cadherin and reverses TGF-ß-induced EMT by reducing DNA methylation, H3K9me2 and H3K27me3 levels at the E-cadherin promoter. Importantly, DNMT3Ab cooperated with H3K9me2 and H3K27me3 contributes to the transcriptional regulation of E-cadherin in a Snail-dependent manner. Further, gene expression profiling analysis indicates that multiple metastasis-associated genes and oncogenic signalling pathways are regulated in response to DNMT3Ab overexpression. These results identify DNMT3Ab as a crucial regulator of metastasis-related genes in GC. Targeting the DNMT3Ab/Snail/E-cadherin axis may provide a promising therapeutic strategy in the treatment of metastatic GC with high DNMT3Ab expression.