Publications by authors named "Joseph C Baker"

Normal mammary gland homeostasis requires the coordinated regulation of protein signaling networks. However, we have little prospective information on whether activation of protein signaling occurs in premalignant mammary epithelial cells, as represented by cells with cytological atypia from women who are at high risk for breast cancer. This information is critical for understanding the role of deregulated signaling pathways in the initiation of breast cancer and for developing targeted prevention and/or treatment strategies for breast cancer in the future.

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Background: Obesity is a well-established risk factor for cancer, accounting for up to 20% of cancer deaths in women. Studies of women with breast cancer have shown obesity to be associated with an increased risk of dying from breast cancer and increased risk of developing distant metastasis. While previous studies have focused on differences in circulating hormone levels as a cause for increased breast cancer incidence in postmenopausal women, few studies have focused on potential differences in the protein expression patterns of mammary epithelial cells obtained from obese versus nonobese women.

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Background: Random periareolar fine needle aspiration (RPFNA) is a research technique developed to assess short-term breast cancer risk in women at increased risk of breast cancer. Although there is increasing acceptance of RPFNA, neither the reproducibility nor the inter-institutional compatibility of RPFNA has been established. To address these key limitations, the Cancer and Leukemia Group B (CALGB) Prevention Group tested the reproducibility of RPFNA in a multi-institutional cross-sectional study.

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Article Synopsis
  • Only 5% of breast cancers are linked to BRCA1/2 mutations, while the role of tumor suppressor gene methylation in familial cases remains unclear.
  • A study examined CpG island promoter methylation in 109 high-risk women, revealing that methylation frequency increased with age, but specific methylation events were not age-related.
  • Women without BRCA1/2 mutations showed significantly higher levels of methylation compared to those with mutations, indicating a potential link between methylation of tumor suppressor genes and non-BRCA1/2 familial breast cancer.
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Purpose: Currently, we lack biomarkers to predict whether high-risk women with mammary atypia will respond to tamoxifen chemoprevention.

Experimental Design: Thirty-four women with cytologic mammary atypia from the Duke University High-Risk clinic were offered tamoxifen chemoprevention. We tested whether ESR1 promoter hypermethylation and/or estrogen receptor (ER) protein expression by immunohistochemistry predicted persistent atypia in 18 women who were treated with tamoxifen for 12 months and in 16 untreated controls.

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  • The study investigates the role of p16(INK4a) in cell cycle regulation and its absence in human mammary epithelial cells, which may lead to increased risk of breast cancer through various dysfunctions and DNA methylation changes.
  • Researchers tested for hypermethylation of the INK4a/ARF promoter in breast tissue samples from 86 asymptomatic women at high risk for breast cancer, alongside evaluating correlation with other methylation markers.
  • Results showed that INK4a/ARF promoter hypermethylation occurs in early stages of neoplasia and normal cells, indicating a potential indicator of broader methylation issues in breast cancer risk, rather than being solely an age-related change.
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  • BRCA1 mutations are linked to familial breast cancer, but the impact of BRCA1 promoter hypermethylation in sporadic cases is unclear.
  • A study assessed the frequency of BRCA1 promoter hypermethylation in 14 breast cancer biopsies and 61 high-risk women’s cytologic samples, finding similar rates across groups regardless of cytologic atypia.
  • Results indicated that BRCA1 promoter hypermethylation is not tied to family history of breast cancer or traditional risk assessment models but is associated with age and the hypermethylation of certain other genes.
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Methylation of the retinoic acid receptor-beta2 (RARbeta2) P2 promoter is hypothesized to be an important mechanism for loss of RARbeta2 function during early mammary carcinogenesis. The frequency of RARbeta2 P2 methylation was tested in (a) 16 early stage breast cancers and (b) 67 random periareolar fine needle aspiration (RPFNA) samples obtained from 38 asymptomatic women who were at increased risk for breast cancer. Risk was defined as either (a) 5-year Gail risk calculation > or = 1.

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