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Estrogen receptor and HER2/neu status affect epigenetic differences of tumor-related genes in primary breast tumors.

Sunami E, Shinozaki M, Sim MS, Nguyen SL, Vu AT, Giuliano AE, Hoon DS - Breast Cancer Res. (2008)

Bottom Line: DNA was extracted from paraffin-embedded tumor tissue after microdissection, and methylation-specific PCR and capillary-array electrophoresis analysis were performed.In early stages of tumor progression (T1 and N0), RASSF1A and CCND2 were significantly (P < 0.05) more methylated in ER-positive than in ER-negative tumors.GSTP1 hypermethylation was more frequent in the lymph node metastasis positive group than in the negative group.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Molecular Oncology, The John Wayne Cancer Institute, Saint John's Health Center, Santa Monica Blvd, Santa Monica, California 90404, USA.

ABSTRACT

Introduction: Estrogen receptor (ER)-positive breast cancers are considered prognostically more favorable than ER-negative tumors, whereas human epidermal growth factor receptor (HER)2/neu-positive breast cancers are associated with worse prognosis. The objective of the present study was to determine whether ER-positive and ER-negative status relates to epigenetic changes in breast cancer-related genes. To evaluate epigenetic differences in tumor-related genes relating to ER and HER2/neu status of primary tumors, we examined the promoter methylation status of the promoter region CpG islands of eight major breast tumor-related genes (RASSF1A, CCND2, GSPT1, TWIST, APC, NES1, RARbeta2, and CDH1).

Methods: Paired ER-positive (n = 65) and ER-negative (n = 65) primary breast tumors (n = 130) matched for prognostic factors were assessed. DNA was extracted from paraffin-embedded tumor tissue after microdissection, and methylation-specific PCR and capillary-array electrophoresis analysis were performed.

Results: In early stages of tumor progression (T1 and N0), RASSF1A and CCND2 were significantly (P < 0.05) more methylated in ER-positive than in ER-negative tumors. GSTP1 hypermethylation was more frequent in the lymph node metastasis positive group than in the negative group. Double negative (ER-negative, HER2/neu-negative) breast cancers had significantly lesser frequencies of RASSF1A, GSTP1, and APC methylation (P < 0.0001, P < 0.0001, and P = 0.0035, respectively). Both ER and HER2/neu status correlated independently with these epigenetic alterations.

Conclusion: We demonstrated significant differences in tumor-related gene methylation patterns relevant to ER and HER2/neu status of breast tumors. This may be of significance in the assessment of targeted therapy resistance related to ER and HER2/neu status in breast cancer patients.

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Related in: MedlinePlus

Methylated and unmethylated markers. Presented are representative methylation-specific PCR results of biomarker RASSF1A from a paraffin-embedded archival breast tissue specimens, showing methylated and unmethylated markers. bp, base pairs.
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Figure 1: Methylated and unmethylated markers. Presented are representative methylation-specific PCR results of biomarker RASSF1A from a paraffin-embedded archival breast tissue specimens, showing methylated and unmethylated markers. bp, base pairs.

Mentions: Initially, the difference in methylation status of eight genes between the age-matched and tumor background-matched ER-negative and ER-positive groups was analyzed using χ2 tests. A representative example of methylated and unmethylated gene analysis from paraffin-embedded tissue is shown in Figure 1. For RASSF1A, CCND2, GSTP1, TWIST, and APC genes, the proportion of methylated genes was significantly higher in the ER-positive than in the ER-negative tumor group. However, no significant differences in methylation status were detected in NES1, RARβ2, and CDH1. Among the eight biomarkers studied, none exhibited predominance of methylation status in ER-negative tumors by univariate analysis (Table 4). Based on this finding, we conducted further analysis of the methylation status of RASSF1A, CCND2, GSTP1, TWIST, and APC. Second, we analyzed the differences in the methylation status of these five tumor-related genes between premenopausal and postmenopausal, T1 and T2/T3, and LN metastasis negative (N0) and positive (N1/N2) subgroups using univariate analysis. Among these five genes, there were no significant differences in methylation frequency between premenopausal and postmenopausal subgroups and T1 and T2/T3 subgroups. Only GSTP1 exhibited significantly more frequent methylation in the N1/N2 subgroup than in the N0 subgroup (Tables 5 to 7).


Estrogen receptor and HER2/neu status affect epigenetic differences of tumor-related genes in primary breast tumors.

Sunami E, Shinozaki M, Sim MS, Nguyen SL, Vu AT, Giuliano AE, Hoon DS - Breast Cancer Res. (2008)

Methylated and unmethylated markers. Presented are representative methylation-specific PCR results of biomarker RASSF1A from a paraffin-embedded archival breast tissue specimens, showing methylated and unmethylated markers. bp, base pairs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2481494&req=5

Figure 1: Methylated and unmethylated markers. Presented are representative methylation-specific PCR results of biomarker RASSF1A from a paraffin-embedded archival breast tissue specimens, showing methylated and unmethylated markers. bp, base pairs.
Mentions: Initially, the difference in methylation status of eight genes between the age-matched and tumor background-matched ER-negative and ER-positive groups was analyzed using χ2 tests. A representative example of methylated and unmethylated gene analysis from paraffin-embedded tissue is shown in Figure 1. For RASSF1A, CCND2, GSTP1, TWIST, and APC genes, the proportion of methylated genes was significantly higher in the ER-positive than in the ER-negative tumor group. However, no significant differences in methylation status were detected in NES1, RARβ2, and CDH1. Among the eight biomarkers studied, none exhibited predominance of methylation status in ER-negative tumors by univariate analysis (Table 4). Based on this finding, we conducted further analysis of the methylation status of RASSF1A, CCND2, GSTP1, TWIST, and APC. Second, we analyzed the differences in the methylation status of these five tumor-related genes between premenopausal and postmenopausal, T1 and T2/T3, and LN metastasis negative (N0) and positive (N1/N2) subgroups using univariate analysis. Among these five genes, there were no significant differences in methylation frequency between premenopausal and postmenopausal subgroups and T1 and T2/T3 subgroups. Only GSTP1 exhibited significantly more frequent methylation in the N1/N2 subgroup than in the N0 subgroup (Tables 5 to 7).

Bottom Line: DNA was extracted from paraffin-embedded tumor tissue after microdissection, and methylation-specific PCR and capillary-array electrophoresis analysis were performed.In early stages of tumor progression (T1 and N0), RASSF1A and CCND2 were significantly (P < 0.05) more methylated in ER-positive than in ER-negative tumors.GSTP1 hypermethylation was more frequent in the lymph node metastasis positive group than in the negative group.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Molecular Oncology, The John Wayne Cancer Institute, Saint John's Health Center, Santa Monica Blvd, Santa Monica, California 90404, USA.

ABSTRACT

Introduction: Estrogen receptor (ER)-positive breast cancers are considered prognostically more favorable than ER-negative tumors, whereas human epidermal growth factor receptor (HER)2/neu-positive breast cancers are associated with worse prognosis. The objective of the present study was to determine whether ER-positive and ER-negative status relates to epigenetic changes in breast cancer-related genes. To evaluate epigenetic differences in tumor-related genes relating to ER and HER2/neu status of primary tumors, we examined the promoter methylation status of the promoter region CpG islands of eight major breast tumor-related genes (RASSF1A, CCND2, GSPT1, TWIST, APC, NES1, RARbeta2, and CDH1).

Methods: Paired ER-positive (n = 65) and ER-negative (n = 65) primary breast tumors (n = 130) matched for prognostic factors were assessed. DNA was extracted from paraffin-embedded tumor tissue after microdissection, and methylation-specific PCR and capillary-array electrophoresis analysis were performed.

Results: In early stages of tumor progression (T1 and N0), RASSF1A and CCND2 were significantly (P < 0.05) more methylated in ER-positive than in ER-negative tumors. GSTP1 hypermethylation was more frequent in the lymph node metastasis positive group than in the negative group. Double negative (ER-negative, HER2/neu-negative) breast cancers had significantly lesser frequencies of RASSF1A, GSTP1, and APC methylation (P < 0.0001, P < 0.0001, and P = 0.0035, respectively). Both ER and HER2/neu status correlated independently with these epigenetic alterations.

Conclusion: We demonstrated significant differences in tumor-related gene methylation patterns relevant to ER and HER2/neu status of breast tumors. This may be of significance in the assessment of targeted therapy resistance related to ER and HER2/neu status in breast cancer patients.

Show MeSH
Related in: MedlinePlus