Debra Shearer

Surfactant protein A, an innate immune factor, is expressed in the vaginal mucosa and is present in vaginal lavage fluid

Surfactant protein A (SP‐A), first identified as a component of the lung surfactant system, is now recognized to be an important contributor to host defence mechanisms. SP‐A can facilitate phagocytosis by opsonizing bacteria, fungi and viruses, stimulate the oxidative burst by phagocytes and modulate pro‐inflammatory cytokine production by phagocytic cells. SP‐A can also provide a link between innate and adaptive immune responses by promoting differentiation and chemotaxis of dendritic cells. Because of the obvious relevance of these mechanisms to the host defence and ‘gate keeping’ functions of the lower genital tract, we examined human vaginal mucosa for SP‐A protein and transcripts and analysed vaginal lavage fluid for SP‐A. By immunocytochemistry, SP‐A was identified in two layers of the vaginal epithelium: the deep intermediate layer (the site of newly differentiated epithelial cells); and the superficial layer (comprising dead epithelial cells), where SP‐A is probably extracellular and associated with a glycocalyx. Transcripts of SP‐A were identified by Northern blot analysis in RNA isolated from vaginal wall and shown, by sequencing of reverse transcription–polymerase chain reaction products, to be derived from each of the two closely related SP‐A genes, SP‐A1 and SP‐A2. SP‐A was identified in vaginal lavage fluid by two‐dimensional gel electrophoresis, and confirmed by mass spectrometry. This study provides evidence, for the first time, that SP‐A is produced in a squamous epithelium, namely the vaginal mucosa, and has a localization that would allow it to contribute to both the innate and adaptive immune response. The findings support the hypothesis that in the vagina, as in lung, SP‐A is an essential component of the host‐defence system. A corollary hypothesis is that qualitative and quantitative alterations of normal SP‐A may play a role in the pathogenesis of lower genital tract inflammatory conditions.

Altered gene expression in breast cancer liver metastases

We previously developed a highly aggressive cell line from heart metastases of 4T1 breast carcinoma (designated 4THM), which produced liver metastases (designated 4TLM). In this study, gene array analysis (GAEA) compared gene expression profiles in 4TLM with profiles in 4T1 and 4THM primary tumors. GAEA demonstrated that 4T1 and 4THM tumors differed in about 250 genes. Over 1,000 genes, however, were expressed differently in 4TLM compared with primary tumors. A cohort of 16 genes showed significantly decreased expression in 4THM tumors, which decreased even further in 4TLM. Many of these genes have been implicated in breast cancer, and many are involved in cell adhesion and junctional complexes. Expression of multiple tight and adherence junction proteins was either downregulated or disappeared in 4TLM; downregulation of claudin 4, claudin 7 and γ‐catenin was confirmed by quantitative polymerase chain reaction, immunoblot, and immunocytochemical (ICC) analyses. At the protein level, intact ZO‐1 was also observed in 4T1 tumors, but was not expressed in 4THM or 4TLM tumors. ICC demonstrated expression of γ‐catenin at the plasma membrane with 4T1 tumors, whereas staining appeared to be nuclear/perinuclear in 4THM tumors. Claudin 7 staining was also seen in monocyte/pmacrophage‐like cells in liver around metastatic lesions by ICC, and it appeared that larger 4TLM tumors apparently reexpressed claudin 7 RNA and protein. Our results demonstrate that decreased or abnormal expression of a number of cell adhesion/junctional proteins, including claudin 4, 7, ZO‐1 and γ‐catenin, correlates with liver metastases, and that cell adhesion molecules in the microenvironment are also altered.

Down-Regulation of HtrA1 Activates the Epithelial-Mesenchymal Transition and ATM DNA Damage Response Pathways

Expression of the serine protease HtrA1 is decreased or abrogated in a variety of human primary cancers, and higher levels of HtrA1 expression are directly related to better response to chemotherapeutics. However, the precise mechanisms leading to HtrA1 down regulation during malignant transformation are unclear. To investigate HtrA1 gene regulation in breast cancer, we characterized expression in primary breast tissues and seven human breast epithelial cell lines, including two non-tumorigenic cell lines. In human breast tissues, HtrA1 expression was prominent in normal ductal glands. In DCIS and in invasive cancers, HtrA1 expression was greatly reduced or lost entirely. HtrA1 staining was also reduced in all of the human breast cancer cell lines, compared with the normal tissue and non-tumorigenic cell line controls. Loss of HtrA1 gene expression was attributable primarily to epigenetic silencing mechanisms, with different mechanisms operative in the various cell lines. To mechanistically examine the functional consequences of HtrA1 loss, we stably reduced and/or overexpressed HtrA1 in the non-tumorigenic MCF10A cell line. Reduction of HtrA1 levels resulted in the epithelial-to-mesenchymal transition with acquisition of mesenchymal phenotypic characteristics, including increased growth rate, migration, and invasion, as well as expression of mesenchymal biomarkers. A concomitant decrease in expression of epithelial biomarkers and all microRNA 200 family members was also observed. Moreover, reduction of HtrA1 expression resulted in activation of the ATM and DNA damage response, whereas overexpression of HtrA1 prevented this activation. Collectively, these results suggest that HtrA1 may function as a tumor suppressor by controlling the epithelial-to-mesenchymal transition, and may function in chemotherapeutic responsiveness by mediating DNA damage response pathways.

Infrared microspectroscopy identifies biomolecular changes associated with chronic oxidative stress in mammary epithelium and stroma of breast tissues from healthy young women: Implications for latent stages of breast carcinogenesis

Studies of the decades-long latent stages of breast carcinogenesis have been limited to when hyperplastic lesions are already present. Investigations of earlier stages of breast cancer (BC) latency have been stymied by the lack of fiducial biomarkers needed to identify where in histologically normal tissues progression toward a BC might be taking place. Recent evidence suggests that a marker of chronic oxidative stress (OxS), protein adducts of 4-hydroxy-2-nonenal (4HNE), can meet this need. Specifically: (1) 4HNE immunopositive (4HNE+) mammary epithelial (ME) cells were found to be prevalent in normal (reduction mammoplasty) tissues of most women (including many teenagers) studied, representative of those living in the United States’ high risk-posing environment and: (2) marked (>1.5-fold) differences were identified between tissues of healthy young women with many vs. few 4HNE+ ME cells in the relative levels of transcripts for 42 of the 84 OxS-associated genes represented in SABioscience Oxidative-Stress/Oxidative-Defense PCR array. Herein we used synchrotron radiation-based Fourier-transform infrared (SR-FTIR) microspectroscopy to identify molecular changes associated with 4HNE adducts in basal and luminal ME cells in terminal ductal units (TDLU), which are the cells of origin of BC, and associated intralobular and interlobular stroma, known contributors to carcinogenesis. Multivariate analysis-derived wavenumbers differentiated 4HNE+ and 4HNE− cells in each of the anatomical compartments. Specifically, principal component and linear discriminant analyses of mid-infrared spectra obtained from these cells revealed unambiguous, statistically highly significant differences in the “biochemical fingerprint” of 4HNE+ vs. 4HNE− luminal and basal ME cells, as well as between associated intralobular and interlobular stroma. These findings demonstrate further SR-FTIR microspectroscopy’s ability to identify molecular changes associated with altered physiological and/or pathophysiological states, in this case with a state of chronic OxS that provides a pro-carcinogenic microenvironment.

Identification of mammary epithelial cells subject to chronic oxidative stress in mammary epithelium of young women and teenagers living in USA: implication for breast carcinogenesis.

Current knowledge of changes in the mammary epithelium relevant to breast carcinogenesis is limited to when histological changes are already present because of a lack of biomarkers needed to identify where such molecular changes might be ongoing earlier during the decades-long latent stages of breast carcinogenesis. Breast reduction tissues from young women and teenagers, representative of the USAs high breast cancer incidence population, were studied using immunocytochemistry and a targeted PCR array in order to learn whether a marker of chronic oxidative stress [protein adducts of 4-hydroxy-2-nonenal (4HNE)] can identify where molecular changes relevant to carcinogenesis might be taking place prior to any histological changes. 4HNE-immunopositive (4HNE+) mammary epithelial cell-clusters were identified in breast tissue sections from most women and from many teenagers (ages 14–30 y) and, in tissues from women ages 17–27 y with many vs. few 4HNE+ cells, the expression of 30 of 84 oxidative stress associated genes represented in SA Bioscience RT2 Oxidative Stress and Antioxidant PCR array was decreased and only one was increased > 2-fold. This is in contrast to increased expression of many of these genes known to be elicited by acute oxidative stress. The findings validate using 4HNE-adducts to identify where molecular changes of potential relevance to carcinogenesis are taking place in histologically normal mammary epithelium and highlight differences between responses to acute vs. chronic oxidative stress. We posit that the altered gene expression in 4HNE+ tissues identified reflects adaptive responses to chronic oxidative stress that enable some cells to evade mechanisms that have evolved to prevent propagation of cells with oxidatively-damaged DNA and to accrue heritable changes needed to establish a cancer.