Bella Maly

Control of Breast Cancer Growth and Initiation by the Stem Cell-Associated Transcription Factor TCF3

Regulatory factors controlling stem cell identity and self-renewal are often active in aggressive cancers and are thought to promote their growth and progression. TCF3 (also known as TCF7L1) is a member of the TCF/LEF transcription factor family that is central in regulating epidermal and embryonic stem cell identity. We found that TCF3 is highly expressed in poorly differentiated human breast cancers, preferentially of the basal-like subtype. This suggested that TCF3 is involved in the regulation of breast cancer cell differentiation state and tumorigenicity. Silencing of TCF3 dramatically decreased the ability of breast cancer cells to initiate tumor formation, and led to decreased tumor growth rates. In culture, TCF3 promotes the sphere formation capacity of breast cancer cells and their self-renewal. We found that in contrast to ES cells, where it represses Wnt-pathway target genes, TCF3 promotes the expression of a subset of Wnt-responsive genes in breast cancer cells while repressing another distinct target subset. In the normal mouse mammary gland, Tcf3 is highly expressed in terminal end buds, structures that lead duct development. Primary mammary cells are dependent on Tcf3 for mammosphere formation, and its overexpression in the developing gland disrupts ductal growth. Our results identify TCF3 as a central regulator of tumor growth and initiation, and a novel link between stem cells and cancer.

Beginning IVF Treatments After Age 30 Increases the Risk of Breast Cancer: Results of a Case–Control Study

Abstract:u2002 The long‐term risks of in vitro fertilization (IVF) treatment remain unclear. This study was designed to determine breast cancer risk factors in women who underwent IVF, and to establish characteristics of these tumors. Records of 7,162 consecutive women who underwent IVF at a single center between 1984 and 2002 were linked with the Israel Cancer Registry to identify women who developed breast cancer. IVF‐related parameters were compared between 28 breast cancer patients who had undergone IVF (IVF BC) and for whom complete IVF data were available with 140 women who underwent IVF and did not develop breast cancer (IVF non‐BC). Tumor parameters were compared between 38 patients who developed breast cancer after IVF and 114 age‐matched breast cancer patients who did not undergo IVF (non‐IVF BC). Age over 30 at the time of first IVF treatment, even after controlling for age at first birth, was the only parameter significantly associated with increased breast cancer risk (RRu2003=u20031.24, pu2003=u20030.02, 95% CIu2003=u20031.03–1.48). There were no differences between IVF‐BC and IVF non‐BC patients in all other IVF‐related parameters. The only statistically significant difference in tumors developing in IVF‐BC patients compared with non‐IVF BC patients was in grade distribution, particularly for grade II tumors. However, the significance of such a difference is unclear. Women who start IVF after the age of 30 appear to be at increased risk of developing breast cancer. The characteristics of breast tumors in women who underwent IVF are no different than in patients without previous exposure to IVF.

EZH2 promotes a bi-lineage identity in basal-like breast cancer cells.

The mechanisms regulating breast cancer differentiation state are poorly understood. Of particular interest are molecular regulators controlling the highly aggressive and poorly differentiated traits of basal-like breast carcinomas. Here we show that the Polycomb factor EZH2 maintains the differentiation state of basal-like breast cancer cells, and promotes the expression of progenitor-associated and basal-lineage genes. Specifically, EZH2 regulates the composition of basal-like breast cancer cell populations by promoting a ‘bi-lineage’ differentiation state, in which cells co-express basal- and luminal-lineage markers. We show that human basal-like breast cancers contain a subpopulation of bi-lineage cells, and that EZH2-deficient cells give rise to tumors with a decreased proportion of such cells. Bi-lineage cells express genes that are active in normal luminal progenitors, and possess increased colony-formation capacity, consistent with a primitive differentiation state. We found that GATA3, a driver of luminal differentiation, performs a function opposite to EZH2, acting to suppress bi-lineage identity and luminal-progenitor gene expression. GATA3 levels increase upon EZH2 silencing, mediating a decrease in bi-lineage cell numbers. Our findings reveal a novel role for EZH2 in controlling basal-like breast cancer differentiation state and intra-tumoral cell composition.

Polymorphous low-grade adenocarcinoma of the submandibular gland.

salivary glands is a relatively new neoplastic entity. It was first described as terminal duct carcinoma in 1983 and defined as PLGA by the World Health Organization in 1990.1 PLGAs usually arise in the minor buccal or palatine salivary glands and are regarded as causing local invasive disease usually without metastasis and with a relatively good prognosis.1 Recently, several reports have been published describing involvement of the major salivary glands, locoregional spread, and distant metastasis.2,3 We describe a patient with PLGA of the submandibular gland, which to the best of our knowledge is the second such case reported in this specific location.4

Identification and Immunolocalization of the Innate Immune Receptor CD14 in Hypertrophic Adenoids and Tonsils

The purpose of this study is to determine the expression of CD14 as a marker of the innate immunity in hypertrophic adenoids and tonsils. Twenty-four pediatric patients (age <12 years) with obstructive adenotonsillar hypertrophy, confirmed by sleep study were included in this study. Intensity and expression of positive CD14 infiltrating cells was assessed by immunohistochemistry in specific histologic areas. In tonsils, CD14 immunoreactivity was demonstrated in intraepithelial lymphocytes located in the basal layer of the stratified squamous mucoepithelium. CD14 expression was significantly higher in mucosal layers and inter-follicular areas of tonsils than adenoid tissues [(p < 0.001), (p = 0.021), respectively]. CD14 expression was significantly higher in the submucosal layers of adenoids than tonsil tissues (p = 0.002). Hypertrophic adenoids and tonsils from children with OSA are prominent sites of innate defense, with over expression of CD14. The enhanced expressions of CD14 cells in adenoids and tonsils may be an important factor for the development and persistence of adenoids and tonsils enlargement causing OSA in children. CD14 expression in adenoids and tonsils illustrates an important immunological sentinel function of the innate immunity of the upper airway.

Regulation of human protease-activated receptor 1 (hPar1) gene expression in breast cancer by estrogen

A pivotal role is attributed to the estrogen‐receptor (ER) pathway in mediating the effect of estrogen in breast cancer progression. Yet the precise mechanisms of cancer development by estrogen remain poorly understood. Advancing tumor categorization a step forward, and identifying cellular gene fingerprints to accompany histopathological assessment may provide targets for therapy as well as vehicles for evaluating the response to treatment. We report here that in breast carcinoma, estrogen may induce tumor development by eliciting protease‐activated receptor‐1 (PAR1) gene expression. Induction of PAR1 was shown by electrophoretic mobility shift assay, luciferase reporter gene driven by the hPar1 promoter, and chromatin‐immunoprecipitation analyses. Functional estrogen regulation of hPar1 in breast cancer was demonstrated by an endothelial tube‐forming network. Notably, tissue‐microarray analyses from an established cohort of women diagnosed with invasive breast carcinoma exhibited a significantly shorter disease‐free (P= 0.006) and overall (P=0.02) survival of patients that were positive for ER and PAR1, compared to ER‐positive but PAR1‐negative patients. We propose that estrogen transcriptionally regulates hPar1, culminating in an aggressive gene imprint in breast cancer. While ER+ patients are traditionally treated with hormone therapy, the presence of PAR1 identifies a group of patients that requires additional treatment, such as anti‐PAR1 biological vehicles or chemotherapy.—Salah, Z., Uziely, B., Jaber, M., Maoz, M., Cohen, I., Hamburger, T., Maly, B., Peretz, T., B.‐S, R. Regulation of human protease‐activated receptor 1 (hPar1) gene expression in breast cancer by estrogen. FASEB J. 26, 2031‐2042 (2012). www.fasebj.org

RNF20 and histone H2B ubiquitylation exert opposing effects in Basal-Like versus luminal breast cancer

Breast cancer subtypes display distinct biological traits that influence their clinical behavior and response to therapy. Recent studies have highlighted the importance of chromatin structure regulators in tumorigenesis. The RNF20-RNF40 E3 ubiquitin ligase complex monoubiquitylates histone H2B to generate H2Bub1, while the deubiquitinase (DUB) USP44 can remove this modification. We found that RNF20 and RNF40 expression and global H2Bub1 are relatively low, and USP44 expression is relatively high, in basal-like breast tumors compared with luminal tumors. Consistent with a tumor-suppressive role, silencing of RNF20 in basal-like breast cancer cells increased their proliferation and migration, and their tumorigenicity and metastatic capacity, partly through upregulation of inflammatory cytokines. In contrast, in luminal breast cancer cells, RNF20 silencing reduced proliferation, migration and tumorigenic and metastatic capacity, and compromised estrogen receptor transcriptional activity, indicating a tumor-promoting role. Notably, the effects of USP44 silencing on proliferation and migration in both cancer subtypes were opposite to those of RNF20 silencing. Hence, RNF20 and H2Bub1 have contrasting roles in distinct breast cancer subtypes, through differential regulation of key transcriptional programs underpinning the distinctive traits of each subtype.