Site-specific Hypermethylation of RUNX3 Predicts Poor Prognosis in Gastric Cancer

BACKGROUND AND AIMS

Methylation status of RUNX3 remains largely unknown in gastric cancer (GC). The aim of this study was to prognostically evaluate the methylation level of CpG sites within RUNX3 promoter region in GC.

METHODS

Using pyrosequencing, we quantitatively explored the methylation status of 8 CpG sites within RUNX3 promoter region for 76 gastric cancer and 24 normal gastric tissues. We then analyzed the association between methylation level of each CpG site and clinicopathological characteristics and outcomes in the cohort.

RESULTS

Methylation of RUNX3 promoter was significantly higher in GC than normal subjects. Overall methylation level was closely associated with tumor invasion and TNM stage. Positive associations were found between hypermethylation of the following concerned sites and variables: site -1392, -1397, -1403, -1415 and tumor invasion, as well as TNM stage; site -1392 and lymph node metastasis along with number of lymph node metastases; site -1415 and cancer recurrence; site -1403, -1415 and cancer-related deaths. In multivariate analysis, tumor invasion was correlated with sites -1392 and -1397. Lymph node metastasis was associated with site -1392. Most importantly, methylation of site -1415 was associated with poor survival by using Cox survival regression.

CONCLUSION

Analysis of RUNX3 gene promoter by quantitative pyrosequencing suggested methylation status of RUNX3 is different in normal and tumor tissues. RUNX3 methylation level is associated with GC, especially the methylation at site -1415 contributes to the poor prognosis in GC. Thus, RUNX3 methylation may serve as a valuable diagnostic and prognostic biomarker in GC.

Transcriptional regulation of gilthead seabream bone morphogenetic protein (BMP) 2 gene by bone- and cartilage-related transcription factors

Bone morphogenetic protein (BMP) 2 belongs to the transforming growth factor β (TGFβ) superfamily of cytokines and growth factors. While it plays important roles in embryo morphogenesis and organogenesis, BMP2 is also critical to bone and cartilage formation. Protein structure and function have been remarkably conserved throughout evolution and BMP2 transcription has been proposed to be tightly regulated, although few data is available. In this work we report the cloning and functional analysis of gilthead seabream BMP2 promoter. As in other vertebrates, seabream BMP2 gene has a 5′ non-coding exon, a feature already present in DPP gene, the fruit fly ortholog of vertebrate BMP2 gene, and maintained throughout evolution. In silico analysis of seabream BMP2 promoter revealed several binding sites for bone and cartilage related transcription factors (TFs) and their functionality was evaluated using promoter-luciferase constructions and TF-expressing vectors. Runt-related transcription factor 3 (RUNX3) was shown to negatively regulate BMP2 transcription and combination with the core binding factor β (CBFβ) further reduced transcriptional activity of the promoter. Although to a lesser extent, myocyte enhancer factor 2C (MEF2C) had also a negative effect on the regulation of BMP2 gene transcription, when associated with SRY (sex determining region Y)-box 9 (SOX9b). Finally, v-ets avian erythroblastosis virus E26 oncogene homolog 1 (ETS1) was able to slightly enhance BMP2 transcription. Data reported here provides new insights toward the better understanding of the transcriptional regulation of BMP2 gene in a bone and cartilage context.

Loss of runt-related transcription factor 3 induces gemcitabine resistance in pancreatic cancer

BACKGROUND & AIM

Runt-related transcription factor 3 (RUNX3) is a tumor suppressor gene that is expressed in gastric and other cancers including pancreatic cancer. However, the precise function of RUNX3 in pancreatic cancer has not been fully elucidated. In this study, we aimed to determine the effect of decreased RUNX3 expression in pancreatic cancer.

METHODS

This study included 36 patients with primary pancreatic cancer, who had undergone pancreaticoduodenectomy. All patients were treated with 1000 mg/m2 gemcitabine after the surgery. The pancreatic cancer cell lines PANC-1, MIAPaCa-2, BxPC-3, SUIT-2, and KLM-1 were used for immunoblotting analysis of RUNX3 and multidrug resistance protein (MRP) expressions. Ectopic RUNX3 expression was achieved by cDNA transfection of the cells, and small interfering RNA (siRNA) against RUNX3 was used to knock down endogenous RUNX3. Cell growth in the presence of gemcitabine was assessed using the MTT assay.

RESULTS

Patients with RUNX3-positive and RUNX3-negative pancreatic cancer had a median survival of 1006 and 643 days, respectively. Exogenous RUNX3 expression reduced the expression of MRP1, MRP2, and MRP5 in endogenous RUNX3-negative cells, whereas RUNX3 siRNA increased the expressions of these genes in endogenous RUNX3-positive cells. Exogenous RUNX3 expression decreased gemcitabine IC50 in RUNX3-negative cells.

CONCLUSION

Loss of RUNX3 expression contributes to gemcitabine resistance by inducing MRP expression, thereby resulting in poor patient survival.