Association of prolactin and its receptor gene regions with familial breast cancer.
ABSTRACT The contribution of prolactin (PRL) through its receptor (PRLR) to the pathogenesis and progression of human mammary tumors has received recent attention.
We investigated whether genetic variation in the PRL and PRLR genes is associated with the risk of breast cancer (BC).
We conducted a case-control study with a total of seven single nucleotide polymorphisms (SNPs).
The study was conducted at an academic research laboratory and university clinics.
A total of 441 German familial, unrelated BC cases and 552 controls matched by age, ethnicity, and geographical region participated in the study.
There were no interventions.
SNP genotype and haplotype distributions and haplotype interactions were correlated with the risk of BC.
Two SNPs (rs1341239 and rs12210179) within the PRL promoter regions were significantly associated with increased risk in homozygotes for the variant alleles [odds ratio (OR), 1.67 and 95% confidence interval (CI), 1.11-2.50; and OR, 2.09 and 95% CI, 1.23-3.52, respectively]. The PRL haplotype containing the variant alleles of the promoter SNPs increased significantly the risk of BC (OR 1.42, 95%CI 1.07-1.90). A PRLR haplotype was associated with a significant decrease in BC risk (OR 0.69, 95% CI 0.54-0.89). An increasing number of PRL and PRLR risk haplotypes led to a significant trend of increasing risk for BC (chi(2) = 12.15; P = 0.007).
Genetic variation in the PRL and PRLR genes was shown to influence BC risk. Additional studies are needed to further clarify the role of the PRL and PRLR genes in the risk of BC.
Article: A comprehensive analysis of common genetic variation in prolactin (PRL) and PRL receptor (PRLR) genes in relation to plasma prolactin levels and breast cancer risk: the multiethnic cohort.[show abstract] [hide abstract]
ABSTRACT: Studies in animals and humans clearly indicate a role for prolactin (PRL) in breast epithelial proliferation, differentiation, and tumorigenesis. Prospective epidemiological studies have also shown that women with higher circulating PRL levels have an increase in risk of breast cancer, suggesting that variability in PRL may also be important in determining a woman's risk. We evaluated genetic variation in the PRL and PRL receptor (PRLR) genes as predictors of plasma PRL levels and breast cancer risk among African-American, Native Hawaiian, Japanese-American, Latina, and White women in the Multiethnic Cohort Study (MEC). We selected single nucleotide polymorphisms (SNPs) from both the public (dbSNP) and private (Celera) databases to construct high density SNP maps that included up to 20 kilobases (kb) upstream of the transcription initiation site and 10 kb downstream of the last exon of each gene, for a total coverage of 59 kb in PRL and 210 kb in PRLR. We genotyped 80 SNPs in PRL and 173 SNPs in PRLR in a multiethnic panel of 349 unaffected subjects to characterize linkage disequilibrium (LD) and haplotype patterns. We sequenced the coding regions of PRL and PRLR in 95 advanced breast cancer cases (19 of each racial/ethnic group) to uncover putative functional variation. A total of 33 and 60 haplotype "tag" SNPs (tagSNPs) that allowed for high predictability (Rh2 > or = 0.70) of the common haplotypes in PRL and PRLR, respectively, were then genotyped in a multiethnic breast cancer case-control study of 1,615 invasive breast cancer cases and 1,962 controls in the MEC. We also assessed the association of common genetic variation with circulating PRL levels in 362 postmenopausal controls without a history of hormone therapy use at blood draw. Because of the large number of comparisons being performed we used a relatively stringent type I error criteria (p < 0.0005) for evaluating the significance of any single association to correct for performing approximately 100 independent tests, close to the number of tagSNPs genotyped for both genes. We observed no significant associations between PRL and PRLR haplotypes or individual SNPs in relation to breast cancer risk. A nominally significant association was noted between prolactin levels and a tagSNP (tagSNP 44, rs2244502) in intron 1 of PRL. This SNP showed approximately a 50% increase in levels between minor allele homozygotes vs. major allele homozygotes. However, this association was not significant (p = 0.002) using our type I error criteria to correct for multiple testing, nor was this SNP associated with breast cancer risk (p = 0.58). In this comprehensive analysis covering 59 kb of the PRL locus and 210 kb of the PRLR locus, we found no significant association between common variation in these candidate genes and breast cancer risk or plasma PRL levels. The LD characterization of PRL and PRLR in this multiethnic population provide a framework for studying these genes in relation to other disease outcomes that have been associated with PRL, as well as for larger studies of plasma PRL levels.BMC Medical Genetics 01/2007; 8:72. · 2.33 Impact Factor
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ABSTRACT: Tumors that express estrogen receptor alpha (ERα+) comprise 75% of breast cancers in women. While treatments directed against this receptor have successfully lowered mortality rates, many primary tumors initially or later exhibit resistance. The paucity of murine models of this "luminal" tumor subtype has hindered studies of factors that promote their pathogenesis and modulate responsiveness to estrogen-directed therapeutics. Since epidemiologic studies closely link prolactin and the development of ERα+ tumors in women, we examined characteristics of the aggressive ERα+ and ERα- carcinomas which develop in response to mammary prolactin in a murine transgenic model (neu-related lipocalin- prolactin (NRL-PRL)). To evaluate their relationship to clinical tumors, we determined phenotypic relationships among these carcinomas, other murine models of breast cancer, and features of luminal tumors in women. We examined a panel of prolactin-induced tumors for characteristics relevant to clinical tumors: histotype, ERα/progesterone receptor (PR) expression and estrogen responsiveness, Activating Protein 1 (AP-1) components, and phosphorylation of signal transducer and activator of transcription 5 (Stat5), extracellular signal regulated kinase (ERK) 1/2 and AKT. We compared levels of transcripts in the ERα-associated "luminal" signature that defines this subtype of tumors in women and transcripts enriched in various mammary epithelial lineages to other well-studied genetically modified murine models of breast cancer. Finally, we used microarray analyses to compare prolactin-induced ERα+ and ERα- tumors, and examined responsiveness to estrogen and the anti-estrogen, Faslodex, in vivo. Prolactin-induced carcinomas were markedly diverse with respect to histotype, ERα/PR expression, and activated signaling cascades. They constituted a heterogeneous, but distinct group of murine mammary tumors, with molecular features of the luminal subtype of human breast cancer. In contrast to morphologically normal and hyperplastic structures in NRL-PRL females, carcinomas were insensitive to ERα-mediated signals. These tumors were distinct from mouse mammary tumor virus (MMTV)-neu tumors, and contained elevated transcripts for factors associated with luminal/alveolar expansion and differentiation, suggesting that they arose from physiologic targets of prolactin. These features were shared by ERα+ and ERα- tumors, suggesting a common origin, although the former exhibited transcript profiles reflecting greater differentiation. Our studies demonstrate that prolactin can promote diverse carcinomas in mice, many of which resemble luminal breast cancers, providing a novel experimental model to examine the pathogenesis, progression and treatment responsiveness of this tumor subtype.Breast cancer research: BCR 01/2011; 13(1):R11. · 5.24 Impact Factor
Article: The effect of neoadjuvant chemotherapy on hormone receptor status, HER2/neu and prolactin in breast cancer.[show abstract] [hide abstract]
ABSTRACT: Histological and immunohistochemical findings may vary in cases of breast cancer. Possible changes in tumor markers between biopsies performed before and after neoadjuvant chemotherapy are controversial and pose a challenge when a clinical decision is needed. The objectives of the present study were: (i) to compare the immunohistochemical expression of estrogen, progesterone and prolactin receptors and HER-2/neu in breast cancer before and after neoadjuvant chemotherapy; and (ii) to correlate the expression of these tumor markers with partial tumor response to neoadjuvant chemotherapy. Immunohistochemical staining for breast tumor markers was performed in 90 cases of breast cancer. Statistical analysis was carried out using Fisher's exact test, McNemar's test, Spearman's correlation and the Kappa index with linear weighting (k). Agreement between markers before and after neoadjuvant chemotherapy was fair to moderate (k = 0.37-0.51). The immunohistochemical expression of HER-2/neu and prolactin receptors showed a significant, albeit weak correlation before and after neoadjuvant chemotherapy (HER-2/neu, rho = 0.34; P = 0.0009; k = 0.35 [95% CI, 0.19-0.51]). Prolactin status changed in 28/90 cases (P = 0.001; McNemar's test), whereas no changes were found in estrogen or progesterone receptors. No association was found between tumor marker expression and tumor response. It seems prudent to reevaluate immunohistochemical markers such as HER-2/neu after neoadjuvant chemotherapy, since the findings will guide the strategy for implementation of adjuvant systemic treatment. No correlation was found between the tumor markers analyzed in the present study and partial tumor response to neoadjuvant chemotherapy.Tumori. 97(6):704-10.