Indira Poola

In the current study we tested if highest incidence of benign as well as cancer growths in breast tissue is due to constitutive molecular composition of this tissue. To delineate the molecular basis, we compared the expression of nine functional gene modules (total 578 genes) that regulate major positive growth and negative inhibitory signals in normal breast with two other reproductive tissues, ovary and uterus. We present data to demonstrate that breast tissues constitutively have very highly elevated levels of several growth promoting molecules and diminished levels of inhibitory molecules which may, in part, contribute for highest incidence of tumor growths in this tissue.

Purpose: It has been reported that approximately a million women are diagnosed with benign breast lesions that include ductal hyperplasias per year in the United States. Recent studies that followed women with benign lesions have established that about 8% to 9% of them will subsequently develop invasive breast cancer (IBC). However, currently, there are no means of identifying a subclass of “true precancerous tissues” in women with ductal hyperplasias who will subsequently develop cancer. The purpose of this study is to investigate whether expression of hyaluronoglucosaminidase 1 (HYAL1), a known tumor promoter, in hyperplastic tissues identifies a “true precancerous stage” and predicts subsequent IBC development. Experimental Design: A retrospective study was conducted with archival benign tissues of various histologic types and clinical information on development/nondevelopment of IBC. The control group was hyperplastic tissues from women who had no prior history of IBC and did not develop cancer in 5 to 7 years after diagnosis (n = 81). The test group was hyperplastic tissues from patients who developed cancer (n = 82). HYAL1 expression was studied by immunohistochemistry, and the results were statistically analyzed for significant association to develop cancer (P value), specificity, sensitivity, positive predictive value, and negative predictive value. Results: Statistical analysis of HYAL1 expression data showed very highly significant association between its expression and subsequent cancer development (P = 0) and very high sensitivity (0.83), specificity (0.84), positive predictive value (0.84), and negative predictive value (0.83). Conclusions: The expression of HYAL1 in ductal hyperplastic tissues is a strong predictor of subsequent development of IBC; therefore, it can be applied as a diagnostic marker either singly or in combination with other marker(s) to screen benign tissues to predict subsequent development of IBC. Detection at the precancerous stage and treatment could drastically cut down breast cancer incidence and deaths from it.

Background: GPR30 is a cell surface estrogen receptor that has been shown to mediate a number of non-genomic rapid effects of estrogen and appear to balance the signaling of estrogen and growth factors. In addition, progestins appear to use GPR30 for their actions. Therefore, GPR30 could play a critical role in hormonal regulation of breast epithelial cell integrity. Deregulation of the events mediated by GPR30 could contribute to tumorigenesis. Methods: To understand the role of GPR30 in the deregulation of estrogen signaling processes during breast carcinogenesis, we have undertaken this study to investigate its expression at mRNA levels in tumor tissues and their matched normal tissues. We compared its expression at mRNA levels by RT quantitative real-time PCR relative to GAPDH in ERα”—positive (n = 54) and ERα”—negative (n = 45) breast cancer tissues to their matched normal tissues. Results: We report here, for the first time, that GPR30 mRNA levels were significantly down-regulated in cancer tissues in comparison with their matched normal tissues (p < 0.0001 by two sided paired t-test). The GPR30 expression levels were significantly lower in tumor tissues from patients (n = 29) who had lymph node metastasis in comparison with tumors from patients (n = 53) who were negative for lymph node metastasis (two sample t-test, p < 0.02), but no association was found with ERα, PR and other tumor characteristics. Conclusions: Down-regulation of GPR30 could contribute to breast tumorigenesis and lymph node metastasis.

The presence of ERα is the basis for treating breast cancer patients with targeted molecular therapies that block estrogen stimulation of breast cancer cell division. To select patients for the above therapies, currently, the ERα presence in breast cancer tissues is determined in clinical laboratories by microscopically scoring the slides subjected to immunohistochemistry (IHC). This method is not quantitative, highly subjective and requires large amount of tumor tissue, therefore, cannot be applied to sterotactic and ultrasound guided biopsy samples. To circumvent these problems, we previously developed quantitative real-time PCR based molecular assay that can be applied to determine mRNA copies of ERα in picogram amounts of total RNA from tumor samples. However, it is not known how the mRNA copy numbers correlate to IHC positive and negative status.

Background: Epidemiologic studies have established that women with prior atypical ductal hyperplastic (ADH) lesions have a 5-fold increased risk of developing invasive breast cancer (IBC). However, there is currently no means of identifying a subclass of ADH from women who will most likely develop cancer. The purpose of this study is to investigate whether elevated expression of carcinoembryonic antigen cell adhesion molecule 6 (CEACAM6) in ADH tissues is associated with the development of IBC.

We have investigated the expression of two estrogen receptor β (ERβ) isoforms, ERβ1 and ERβ5, which activate gene transcription independent of estrogen or growth factors, in ERα-negative breast cancer tissues. We report here, for the first time, that ERα-negative tissues express significant levels of ERβ1 and ERβ5, and their expression levels are not different from levels in ERα positive tumors. However, significant differences exist between the two racial groups, African American and Caucasian, in that the patients from the former group express higher levels of ERβ1 and ERβ5 but not ERα. These two transcription factors could be potential molecular targets for designing chemopreventive drugs to treat ERα-negative breast cancers.

Breast cancer is the second leading cause of cancer death for women in the United States. In 2005, about 215,000 cases of invasive breast cancer (IBC) and 50,000 cases of ductal carcinoma in situ will be diagnosed and 40,000 women will die of IBC in the US¹. Yet there is presently no molecular marker that can be used to detect a precancerous state or identify which premalignant lesions will develop into invasive breast cancer. Here we report the gene expression analysis of atypical ductal hyperplastic tissues from patients with and without a history of breast cancer. We identify MMP-1 as a candidate marker that may be useful for identification of breast lesions that can develop into cancer.

We describe here the cloning and functional characterization of two unique ER isoforms, ERβ4 and ERβ5. The full length ERβ4 and ERβ5 were identified by asymmetric PCR using human ovary cDNA, cloning, and sequence analyses. Both receptors share identical sequences with ERβ1 from exon 1 to exon 7. In the place of exon 8, ERβ4 has unique sequences arising from a region downstream of the ERβ gene and upstream of the SYNE2 gene. ERβ5 has sequences arising from retention of the 5′ end of the intron between exon 7 and 8. Both receptors bind promoter sequences on DNA but do not bind estrogen. They translocate to the nucleus and exhibit three to four times higher estrogen-independent transcriptional activity than ERβ1. When co-transfected with ERα, they predominantly form heterodimers and negatively regulate its transcriptional activity. Estrogen-independent transcriptional activity of ERβ5, but not ERβ4, was inhibited by ERα, demonstrating for the first time that ERα regulates ERβ. Tissue-specific expression of ERβ4 and ERβ5, together with their ligand-independent transcriptional properties and ERα modulating activities, could have a number of implications in seemingly unlinked biological processes regulated by estrogen.