Simultaneous CXCL12 and ESR1 CpG island hypermethylation correlates with poor prognosis in sporadic breast cancer

Abstract

BackgroundCXCL12 is a chemokine that is constitutively expressed in many organs and tissues. CXCL12 promoter hypermethylation has been detected in primary breast tumours and contributes to their metastatic potential. It has been shown that the oestrogen receptor α (ESR1) gene can also be silenced by DNA methylation. In this study, we used methylation-specific PCR (MSP) to analyse the methylation status in two regions of the CXCL12 promoter and ESR1 in tumour cell lines and in primary breast tumour samples, and correlated our results with clinicopathological data.MethodsFirst, we analysed CXCL12 expression in breast tumour cell lines by RT-PCR. We also used 5-aza-2'-deoxycytidine (5-aza-CdR) treatment and DNA bisulphite sequencing to study the promoter methylation for a specific region of CXCL12 in breast tumour cell lines. We evaluated CXCL12 and ESR1 methylation in primary tumour samples by methylation-specific PCR (MSP). Finally, promoter hypermethylation of these genes was analysed using Fisher's exact test and correlated with clinicopathological data using the Chi square test, Kaplan-Meier survival analysis and Cox regression analysis.ResultsCXCL12 promoter hypermethylation in the first region (island 2) and second region (island 4) was correlated with lack of expression of the gene in tumour cell lines. In the primary tumours, island 2 was hypermethylated in 14.5% of the samples and island 4 was hypermethylated in 54% of the samples. The ESR1 promoter was hypermethylated in 41% of breast tumour samples. In addition, the levels of ERα protein expression diminished with increased frequency of ESR1 methylation (p < 0.0001). This study also demonstrated that CXCL12 island 4 and ESR1 methylation occur simultaneously at a high frequency (p = 0.0220).ConclusionsThis is the first study showing a simultaneous involvement of epigenetic regulation for both CXCL12 and ESR1 genes in Brazilian women. The methylation status of both genes was significantly correlated with histologically advanced disease, the presence of metastases and death. Therefore, the methylation pattern of these genes could be used as a molecular marker for the prediction of breast cancer outcome.

Down-Regulation of CXCL12 by DNA Hypermethylation and Its Involvement in Gastric Cancer Metastatic Progression

“…One of our objectives was to verify whether the aberrant methylation findings were in gastric carcinomas. We evaluated the CpG islands of the CXCL12 gene that had already been analyzed by another group that found DNA methylation in colon cancer and mammary carcinoma [17,18,20]. In our research, the CpG islands of the CXCL12 gene was hypermethylated in 2 of 3 gastric cancer cells, but not in GES1 cells, and as high as 65.7% in the 35 primary gastric tumors, whereas only 11.4% hypermethylation of CXCL12 was observed in corresponding normal gastric tissues.…”

“…Moreover, we also found that the expression of CXCL12 was frequently reduced in gastric primary carcinomas when compared to corresponding normal gastric tissues. Other researchers found the same phenomenon in colon cancer, mammary carcinoma, and non-small lung cancer, and the CpG islands of the CXCL12 gene was hypermethylated [17][18][19][20]. One of our objectives was to verify whether the aberrant methylation findings were in gastric carcinomas.…”

“…Recent studies have also reported that the epigenetic down-regulation of CXCL12 modulates the metastatic potential of breast, colon carcinoma, and non-small cell lung cancer [17][18][19][20][21]. Also, a previous study showed that many gastric cancer cell lines do not express CXCL12 [22]; however, CXCL12 protein levels were present in gastric cancer tissues by immunohistochemistry [23].…”

CXCL12 and ADAM23 hypermethylation are associated with advanced breast cancers

“…In previous studies, a strong association between CXCL12 hypermethylation and a histologically advanced disease, the presence of metastases, and death in patients with BC was found. 23,24 The tissue inhibitors of metalloproteinases (TIMPs) prevent the degradation of the extracellular matrix. TIMP3 is a matrix-binding protein that regulates the matrix composition and affects tumor growth, angiogenesis, invasion, and metastasis.…”

Estrogen and its role in thyroid cancer

“…DNA methylation may silence the promoter of the ESR1 gene that encodes ERa, which occurs in the pathogenesis of different cancers (Yao et al 2010, Wei et al 2012. In breast cancer, DNA hypermethylation is a major reason for the loss of ERa expression and confers a poor prognosis to this tumor (Ramos et al 2010). …”