Steroid Hormone Receptors as Prognostic Markers in Breast Cancer

Despite the existence of many promising anti-cancer therapies, not all breast cancers are equally treatable, due partly to the fact that focus has been primarily on a few select breast cancer biomarkers- notably ERα, PR and HER2. In cases like triple negative breast cancer (ERα-, PR-, and HER2-), there is a complete lack of available biomarkers for prognosis and therapeutic purposes. The goal of this review is to determine if other steroid receptors, like ERβ and AR, could play a prognostic and/or therapeutic role. Data from various in vitro, in vivo, and clinical breast cancer studies were examined to analyze the presence and function of ERβ, PR, and AR in the presence and absence of ERα. Additionally, we focused on studies that examined how expression of the various steroid receptor isoforms affects breast cancer progression. Our findings suggest that while we have a solid understanding of how these receptors work individually, how they interact and behave in the presence and absence of other receptors requires further research. Furthermore, there is an incomplete understanding of how the various steroid receptor isoforms interact and impact receptor function and breast cancer progression, partly due to the difficulty in detecting all the various isoforms. More large-scale clinical studies must be made to analyze systematically the expression of steroid hormone receptors and their respective isoforms in breast cancer patients in order to determine how these receptors interact with each other and in turn affect cancer progression

Glycosylation of cyclooxygenase-2 (COX-2) influences the migratory and invasive potential of cells

Prostaglandins are bioactive lipids involved in many physiological functions such as maintenance of the cardiovascular, immune, renal, and central nervous systems. They also play a role in certain diseases like arthritis, cancer, and Alzheimer’s. Cyclooxygenase-2 (COX-2) is the enzyme that catalyzes the initial rate-limiting step in the pathway that converts arachidonic acid to prostaglandins. COX-2 exists as two glycoforms with the molecular weights of 72 and 74 kDa, the latter resulting from the addition of a high mannose chain to the Asn580 residue ~50% of the time. The over-expression of COX-2 is believed to be linked to cancer progression and specifically appears to promote the metastatic phenotype. The objective of this study is to determine the effect of the variable glycosylation of COX-2 at Asn580 on the migratory and invasive potential of cells. COS-1 cells and the breast cancer cell line MCF7 were first transfected with either the wild type or Asn580-mutant human COX-2 gene. Boyden chambers were used to determine the ability of transfected cells to migrate through the membrane, approximately 5x104 cells were plated onto the chambers, and cells were incubated for 16-18 h. Cells were then fixed, stained, visualized and counted. In a previous study, our lab showed that COS-1 cells transfected with the Asn580-mutant COX-2 gene migrated faster through the membrane. In this current study, COS-1 cells transfected with the Asn580-mutant COX-2 gene also had a greater invasive potential; however, MCF7 cells transfected with the wild-type human COX-2 gene migrated faster and also had a greater tendency to invade. The results indicate that the ability of this additional or the lack of glycosylation of COX-2 at Asn580 to either enhance or inhibit the migratory and invasive potential of cells depends greatly on cell type. To confirm this, future studies will be carried out to determine the effect of COX-2 glycosylation on the invasive and the migratory potential of PC-3 and T-47D cancer cell lines.https://scholar.dominican.edu/natural-sciences-and-mathematics-faculty-research-posters/1000/thumbnail.jp

Glycosylation of cyclooxygenase-2 (COX-2) influences the migratory potential of COS-1 cells

A cancer cell’s most threatening property is its ability to metastasize or detach from the primary tumor and migrate to other locations in the body. Previous studies have shown that overexpression of the enzyme cyclooxygenase-2 (COX-2) can increase the metastatic potential of several cell types. COX-2 is the rate-limiting enzyme in the prostanoid biosynthesis pathway, converting arachidonic acid to prostaglandin H2, an important signaling molecule in the body. Glycosylation of COX-2 at the amino acid site Asn580 occurs about 50% of the time, and this results in two forms of the enzyme with molecular weights 72 and 74kDa. The purpose of this study was to investigate the impact of glycosylation of COX-2 at the Asn580 site on the metastatic potential of cells. COS-1 cells were first transfected with either an Asn580-mutant human COX-2 gene or the wild-type human COX-2 gene. A cell migration assay was then carried out on these two groups of cells. Briefly, 5x104 cells were plated onto the membrane of a Boyden Chamber, and cells were incubated for 12 hours. Cells that migrated to the underside of the membrane were fixed, stained, visualized via light microscopy, and counted. Our results revealed that cells transfected with the Asn580-mutant gene migrated faster through the membrane. This indicates that a lack of glycosylation at the Asn580 site of the COX-2 enzyme may lead to an enhanced metastatic potential in cells. Future studies will analyze the effect of variable COX-2 glycoform expression on the migratory potential of tumor cell lines such as MCF-7 and T-47D.https://scholar.dominican.edu/natural-sciences-and-mathematics-faculty-research-posters/1001/thumbnail.jp

Effect of Cyclooxygenase-2 Glycosylation on Downstream Expression of E-Cadherin and β-Catenin in MCF-7 Breast Cancer Cells

Cyclooxygenase-2 (COX-2) is an enzyme that helps catalyze the formation of prostaglandins, which promote inflammation, pain, and fever and maintain other normal physiological functions throughout the body. However, the overexpression of COX-2 has been found to play a role in various diseases including breast cancer. COX-2 exists as two major glycoforms— 72 kDa and 74 kDa— due to the glycosylation site Asn580 which is glycosylated 50% of the time. Past studies from our lab have shown that this glycosylation regulates COX-2 protein turnover in the cell3. The proteins E-cadherin— a tumor suppressor— and β-catenin— a tumor driver— can be regulated by COX-2 activityhttps://scholar.dominican.edu/natural-sciences-and-mathematics-faculty-research-posters/1002/thumbnail.jp

Glycosylation of human cyclooxygenase-2 (COX-2) decreases the efficacy of certain COX-2 inhibitors.

Prostanoids play an important role in a variety of physiological and pathophysiological processes including inflammation and cancer. The rate-limiting step in the prostanoid biosynthesis pathway is catalyzed by cyclooxygenase-2 (COX-2). COX-2 exists as two glycoforms, 72 and 74 kDa, the latter resulting from an additional glycosylation at Asn(580). In this study, Asn(580) was mutated, and the mutant and wild-type COX-2 genes were expressed in COS-1 cells to determine how glycosylation affects the inhibition of COX-2 activity by aspirin, flurbiprofen, ibuprofen, celecoxib, and etoricoxib. Results indicate that certain inhibitors were 2-5 times more effective at inhibiting COX-2 activity when the glycosylation site was eliminated, indicating that glycosylation of COX-2 at Asn(580) decreases the efficacy of some inhibitors

Antibacterial activity of native California medicinal plant extracts isolated from Rhamnus californica and Umbellularia californica.

BACKGROUND: Antimicrobial resistance (AMR) is a major threat to global public health. Medicinal plants have long been used as remedies for infectious diseases by native cultures around the world and have the potential for providing effective treatments for antibiotic-resistant infections. Rhamnus californica (Rhamnaceae) and Umbellularia californica (Lauraceae) are two indigenous California plant species historically used by Native Americans to treat skin, respiratory and gastrointestinal infections. This study aimed to assess the in vitro antimicrobial activity of methanolic extracts of leaves and bark of R. and U. californica against methicillin-resistant Staphylococcus aureus (MRSA) and other Gram-positive and Gram-negative bacteria. METHODS: Methanolic extracts of leaves and bark of R. and U. californica were prepared by soxhlet extraction and evaluated for their antimicrobial activity against Bacillus cereus, Streptococcus pyogenes, Mycobacterium smegmatis, Staphylococcus aureus, MRSA, Escherichia coli and Pseudomonas aeruginosa using disc diffusion and minimal inhibitory concentration (MIC) assays. Chemical profiling of the extracts was performed using standard methods. RESULTS: All extracts inhibited the growth of MRSA and other Gram-positive bacteria with MICs of 3.3-6.0 mg/ml. Gram-negative organisms were unaffected by these extracts. U. californica extracts (leaves and bark) had the lowest MIC values. Chemical profiling detected the presence of quinones, alkaloids, flavonoids, cardenolides, tannins and saponins in these extracts. Our study is the first to report the antimicrobial properties of R. and U. californica and illustrates their promising anti-MRSA potential. CONCLUSIONS: Our results give scientific credence to the traditional medicinal uses of these plants by the indigenous peoples of California. Further investigation of the secondary metabolites responsible for the antimicrobial activity of these extracts against MRSA is warranted

Novel flexible heteroarotinoid, SL-1-39, inhibits HER2-positive breast cancer cell proliferation by promoting lysosomal degradation of HER2.

SL-1-39 [1-(4-chloro-3-methylphenyl)-3-(4-nitrophenyl)thiourea] is a new flexible heteroarotinoid (Flex-Het) analog derived from the parental compound, SHetA2, previously shown to inhibit cell growth across multiple cancer types. The current study aims to determine growth inhibitory effects of SL-1-39 across the different subtypes of breast cancer cells and delineate its molecular mechanism. Our results demonstrate that while SL-1-39 blocks cell proliferation of all breast cancer subtypes tested, it has the highest efficacy against HER2+ breast cancer cells. Molecular analyses suggest that SL-1-39 prevents S phase progression of HER2+ breast cancer cells (SKBR3 and MDA-MB-453), which is consistent with reduced expression of key cell-cycle regulators at both the protein and transcriptional levels. SL-1-39 treatment also decreases the protein levels of HER2 and pHER2 as well as its downstream effectors, pMAPK and pAKT. Reduction of HER2 and pHER2 at the protein level is attributed to increased lysosomal degradation of total HER2 levels. This is the first study to show that a flexible heteroarotinoid analog modulates the HER2 signaling pathway through lysosomal degradation, and thus further warrants the development of SL-1-39 as a therapeutic option for HER2+ breast cancer

Glycosylation regulates turnover of cyclooxygenase-2

AbstractCyclooxygenase-2 (COX-2) catalyzes the rate-limiting step in the prostanoid biosynthesis pathway, converting arachidonic acid into prostaglandin H2. COX-2 exists as 72 and 74kDa glycoforms, the latter resulting from an additional oligosaccharide chain at residue Asn580. In this study, Asn580 was mutated to determine the biological significance of this variable glycosylation. COS-1 cells transfected with the mutant gene were unable to express the 74kDa glycoform and were found to accumulate more COX-2 protein and have five times greater COX-2 activity than cells expressing both glycoforms. Thus, COX-2 turnover appears to depend upon glycosylation of the 72kDa glycoform

The Role of Cadmium and Nickel in Estrogen Receptor Signaling and Breast Cancer: Metalloestrogens or Not?

During the last half-century, incidences of breast cancer have increased globally. Various factors —genetic and environmental— have been implicated in the initiation and progression of this disease. One potential environmental risk factor that has not received a lot of attention is the exposure to heavy metals. While several mechanisms have been put forth describing how high concentrations of heavy metals play a role in carcinogenesis, it is unclear whether chronic, lowlevel exposure to certain heavy metals (i.e. cadmium and nickel), can directly result in the development and progression of cancer. Cadmium and nickel have been hypothesized to play a role in breast cancer development by acting as metalloestrogens— metals that bind to estrogen receptors and mimic the actions of estrogen. Since the lifetime exposure to estrogen is a wellestablished risk factor for breast cancer, anything that mimics its activity will likely contribute to the etiology of the disease. However, heavy metals, depending on their concentration, are capable of binding to a variety of proteins and may exert their toxicities by disrupting multiple cellular functions, complicating the analysis of whether heavy metal-induced carcinogenesis is mediated by the estrogen receptor. The purpose of this review is to discuss the various epidemiological, in vivo, and in vitro studies that show a link between the heavy metals, cadmium and nickel, and breast cancer development. We will particularly focus on the studies that test whether or not these two metals act as metalloestrogens in order to assess the strength of the data supporting this hypothesis

Steroid hormone receptors as prognostic markers in breast cancer.

Despite the existence of many promising anti-cancer therapies, not all breast cancers are equally treatable, due partly to the fact that focus has been primarily on a few select breast cancer biomarkers- notably ERα, PR and HER2. In cases like triple negative breast cancer (ERα- , PR- , and HER2- ), there is a complete lack of available biomarkers for prognosis and therapeutic purposes. The goal of this review is to determine if other steroid receptors, like ERβ and AR, could play a prognostic and/or therapeutic role. Data from various in vitro, in vivo, and clinical breast cancer studies were examined to analyze the presence and function of ERβ, PR, and AR in the presence and absence of ERα. Additionally, we focused on studies that examined how expression of the various steroid receptor isoforms affects breast cancer progression. Our findings suggest that while we have a solid understanding of how these receptors work individually, how they interact and behave in the presence and absence of other receptors requires further research. Furthermore, there is an incomplete understanding of how the various steroid receptor isoforms interact and impact receptor function and breast cancer progression, partly due to the difficulty in detecting all the various isoforms. More large-scale clinical studies must be made to analyze systematically the expression of steroid hormone receptors and their respective isoforms in breast cancer patients in order to determine how these receptors interact with each other and in turn affect cancer progression