RESUMO
Cancer-associated fibroblasts (CAFs) tend to have tumor-promoting capacity, and can provide therapeutic targets. Even without cancer cells, CAF phenotypes are stably maintained, and DNA methylation and H3K27me3 changes have been shown to be involved. Here, we searched for a potential therapeutic target in primary CAFs from gastric cancer and a mechanism for its dysregulation. Expression microarray using eight CAFs and seven non-CAFs (NCAFs) revealed that serum amyloid A1 (SAA1), which encodes an acute phase secreted protein, was second most upregulated in CAFs, following IGF2. Conditioned medium (CM) derived from SAA1-overexpressing NCAFs was shown to increase migration of gastric cancer cells compared with that from control NCAFs, and its tumor-promoting effect was comparable to that of CM from CAFs. In addition, increased migration of cancer cells by CM from CAFs was mostly canceled with CM from CAFs with SAA1 knockdown. Chromatin immunoprecipitation (ChIP)-quantitative PCR showed that CAFs had higher levels of H3K27ac, an active enhancer mark, in the promoter and the two far upstream regions of SAA1 than NCAFs. Also, BET bromodomain inhibitors, JQ1 and mivebresib, decreased SAA1 expression and tumor-promoting effects in CAFs, suggesting SAA1 upregulation by enhancer activation in CAFs. Our present data showed that SAA1 is a candidate therapeutic target from gastric CAFs and indicated that increased enhancer acetylation is important for its overexpression.
Assuntos
Fibroblastos Associados a Câncer/metabolismo , Proteína Amiloide A Sérica/genética , Neoplasias Gástricas/patologia , Acetilação , Azepinas/farmacologia , Azepinas/uso terapêutico , Fibroblastos Associados a Câncer/efeitos dos fármacos , Proteínas de Ciclo Celular/antagonistas & inibidores , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Movimento Celular/genética , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Meios de Cultivo Condicionados/metabolismo , Elementos Facilitadores Genéticos , Gastrectomia , Mucosa Gástrica/citologia , Mucosa Gástrica/patologia , Mucosa Gástrica/cirurgia , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Técnicas de Silenciamento de Genes , Humanos , Cultura Primária de Células , Piridonas/farmacologia , Piridonas/uso terapêutico , Proteína Amiloide A Sérica/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Neoplasias Gástricas/tratamento farmacológico , Neoplasias Gástricas/cirurgia , Sulfonamidas/farmacologia , Sulfonamidas/uso terapêutico , Fatores de Transcrição/antagonistas & inibidores , Fatores de Transcrição/metabolismo , Triazóis/farmacologia , Triazóis/uso terapêutico , Regulação para CimaRESUMO
OBJECTIVE: Cancer-associated fibroblasts (CAFs), a major component of cancer stroma, can confer aggressive properties to cancer cells by secreting multiple factors. Their phenotypes are stably maintained, but the mechanisms are not fully understood. We aimed to show the critical role of epigenetic changes in CAFs in maintaining their tumour-promoting capacity and to show the validity of the epigenomic approach in identifying therapeutic targets from CAFs to starve cancer cells. DESIGN: Twelve pairs of primary gastric CAFs and their corresponding non-CAFs (NCAFs) were established from surgical specimens. Genome-wide DNA methylation and H3K27me3 analyses were conducted by BeadArray 450K and ChIP-on-Chip, respectively. Functions of potential a therapeutic target were analysed by inhibiting it, and prognostic impact was assessed in a database. RESULTS: CAFs had diverse and distinct DNA methylation and H3K27me3 patterns compared with NCAFs. Loss of H3K27me3, but not DNA methylation, in CAFs was enriched for genes involved in stem cell niche, cell growth, tissue development and stromal-epithelial interactions, such as WNT5A, GREM1, NOG and IGF2. Among these, we revealed that WNT5A, which had been considered to be derived from cancer cells, was highly expressed in cancer stromal fibroblasts, and was associated with poor prognosis. Inhibition of secreted WNT5A from CAFs suppressed cancer cell growth and migration. CONCLUSIONS: H3K27me3 plays a crucial role in defining tumour-promoting capacities of CAFs, and multiple stem cell niche factors were secreted from CAFs due to loss of H3K27me3. The validity of the epigenetic approach to uncover therapeutic targets for cancer-starving therapy was demonstrated.
Assuntos
Fibroblastos Associados a Câncer/metabolismo , Histona Desmetilases com o Domínio Jumonji/genética , Neoplasias Gástricas/genética , Meios de Cultivo Condicionados , Metilação de DNA , DNA de Neoplasias/genética , Epigenômica/métodos , Ontologia Genética , Estudo de Associação Genômica Ampla/métodos , Humanos , Histona Desmetilases com o Domínio Jumonji/deficiência , Mutação , Nicho de Células-Tronco , Neoplasias Gástricas/metabolismo , Neoplasias Gástricas/patologia , Células Tumorais CultivadasRESUMO
DNA demethylation therapy is now expanding from hematological tumors to solid tumors. To exploit its maximum efficacy, long-term treatment is needed, and stratification of sensitive patients is critically important. Here, we identified a long non-coding RNA, LINC00162, as highly and frequently expressed in gastric cancer cell lines sensitive to 5-aza-2'-deoxycytidine (5-aza-dC). Knockdown of LINC00162 decreased the sensitivity while its overexpression increased the sensitivity. In vivo experiments also showed that LINC00162 overexpression increased the sensitivity. LINC00162 enhanced cell cycle arrest and apoptosis induced by 5-aza-dC, but did not affect its DNA demethylation effect. Mechanistically, LINC00162 interacted with an RNA splicing protein, HNRNPH1, and decreased splicing of an anti-apoptotic splicing variant, BCL-XL. LINC00162 may have translational value to predict patients who will respond to 5-aza-dC.