Identification of an Optimized Receptor-Binding Domain Subunit Vaccine against SARS-CoV-2.

Current vaccine efforts to combat SARS-CoV-2 are focused on the whole spike protein administered as mRNA, viral vector, or protein subunit. However, the SARS-CoV-2 receptor-binding domain (RBD) is the immunodominant portion of the spike protein, accounting for 90% of serum neutralizing activity. In this study, we constructed several versions of RBD and together with aluminum hydroxide or DDA (dimethyldioctadecylammonium bromide)/TDB (d-(+)-trehalose 6,6'-dibehenate) adjuvant evaluated immunogenicity in mice. We generated human angiotensin-converting enzyme 2 knock-in mice to evaluate vaccine efficacy in vivo following viral challenge. We found that 1) subdomain (SD)1 was essential for the RBD to elicit maximal immunogenicity; 2) RBDSD1 produced in mammalian HEK cells elicited better immunogenicity than did protein produced in insect or yeast cells; 3) RBDSD1 combined with the CD4 Th1 adjuvant DDA/TDB produced higher neutralizing Ab responses and stronger CD4 T cell responses than did aluminum hydroxide; 4) addition of monomeric human Fc receptor to RBDSD1 (RBDSD1Fc) significantly enhanced immunogenicity and neutralizing Ab titers; 5) the Beta version of RBDSD1Fc provided a broad range of cross-neutralization to multiple antigenic variants of concern, including Omicron; and 6) the Beta version of RBDSD1Fc with DDA/TDB provided complete protection against virus challenge in the knock-in mouse model. Thus, we have identified an optimized RBD-based subunit vaccine suitable for clinical trials.

Risk of radial head arthroplasty revision is correlated with radial head diameter: a multicenter analysis of 405 cases.

BACKGROUND: Radial head arthroplasty (RHA) is commonly used for the treatment of comminuted radial head fractures. Indications as well as implant types continue to evolve. RHA has had good outcomes with midterm longevity. The literature is limited to small case series with varying implant types, and larger studies are needed to determine the optimal implant type and radial head diameter. METHODS: A retrospective analysis of RHA cases performed by 75 surgeons at 14 medical centers in an integrated health care system between 2006 and 2017 was completed. Patient demographics, comorbidities, implant type and head diameter, and indications for revision were recorded. Patients' in-person clinical visit data were recorded. Patients were also contacted via telephone at a minimum of 2 years to obtain abbreviated Disabilities of the Arm, Shoulder, and Hand questionnaire and Oxford scores. Implant survivorship was also captured within our integrated system. RESULTS: 405 cases met our inclusion criteria. Mean age was 51.5 ± 15.5 years (range 16-88 years) and more common in females (62%). Chart review and telephone follow-up was performed at a mean of 68.9 ± 31.5 months (range 24-146 months). Our study found that revision rate was positively correlated with increasing radial head diameter. A 26-mm head had 7.7 odds of revision compared to a size 18-mm head (95% confidence interval 1.2-150.1). More than 95% of revision cases were performed within the first 36 months of the index procedure. Obese patients had a significantly lower mean postoperative Oxford score (35.5) compared to controls (38.3) (P = .02). There was a significantly higher overall reoperation rate for terrible triad (18.4%) vs. isolated injuries (10.4%) (P = .04). There was no difference between Acumed Anatomic and Evolve radial head implants in overall reoperation, implant revision, postoperative range of motion, or patient-reported outcomes. CONCLUSIONS: Risk of revision is directly correlated with implanted radial head diameter. There were no differences in outcomes and complications between the 2 main implants used. Individuals who did not undergo a revision by 3 years' time tend to retain the implant. Terrible triad injuries had a higher all-cause reoperation rate than isolated radial head fractures, but no difference in the rate of RHA revision. These data reinforce the practice of downsizing radial head implant diameter.

Targeted Secondary Screening for Congenital Hypothyroidism in High-Risk Neonates: A 9 Year Review in a Large California Health Care System.

Secondary screening for missed congenital hypothyroidism (CH) has been introduced sporadically, but its necessity and optimal strategy have not been recognized. We hypothesized that a simple clinical protocol (performed by a medical group without a governmental mandate) targeting infants at high risk for missed CH can identify cases. We performed a 9-year retrospective review of 338,478 neonates within a California health plan following the introduction of thyrotropin (TSH) secondary screening for neonates at high risk for missed CH due to very-low-birthweight (VLBW), hospitalized congenital heart disease (CHD), and same-sex multiples (SSM). Screening performance by day 60 of life was 95% successful for VLBW and >50% for CHD and SSM, leading to an additional 35% CH treated cases despite re-testing only 1.7% of the cohort. Infants with VLBW or CHD were 33 times more likely (190 times more likely for CHD with Down Syndrome) to receive treatment for CH than random infants diagnosed by primary screening (p < 0.001), and 92% of these infants were not found by primary newborn screening. Currently, permanent disease has been documented in 84% of CH by primary screening compared to 27% by secondary screening (p < 0.001). This targeted secondary screening program identifies and treats additional CH cases after TSH-only newborn screening.

Survival and risk of recurrence of takotsubo syndrome.

OBJECTIVE: The goal of this study is to evaluate the long-term outcomes of patients with takotsubo syndrome and assess factors associated with death or recurrence. METHODS: This is a retrospective population-based cohort study of consecutive patients who presented to an integrated health system in Southern California with takotsubo syndrome between 2006 and 2016. Medical records were manually reviewed to confirm diagnosis and to identify predisposing factors, medication treatment and long-term outcomes. Factors associated with death or recurrent takotsubo syndrome were tested using Cox regression models. RESULTS: Between 2006 and 2016, there were 519 patients with a confirmed diagnosis of takotsubo syndrome. Patients were followed for 5.2 years (IQR 3.0-7.2). During the follow-up period, 39 (7.5%) had recurrent takotsubo syndrome and 84 (16.2%) died. In multivariate modelling, factors associated with higher risk of recurrence or death were age (HR 1.56 per 10-year increase, 95% CI 1.29 to 1.87), male sex (HR 2.52, 95% CI 1.38 to 4.60), diabetes (HR 1.6, 95% CI 1.06 to 2.43), pulmonary disease (HR 2.0, 95% CI 1.37 to 2.91) and chronic kidney disease (HR 1.58, 95% CI 1.01 to 2.47). Treatment with beta-blockers were associated with lower risk of recurrence or death (HR 0.46, 95% CI 0.29 to 0.72). No association was observed between treatment with ACE inhibitors or angiotensin-receptor blockers and recurrence or death (HR 0.92, 95% CI 0.59 to 1.42). CONCLUSIONS: Recurrent takotsubo syndrome occurred in a minor subset of patients. Treatment with beta-blocker was associated with higher event-free survival.

Clinical Characteristics and Outcomes of Patients With Takotsubo Syndrome.

BACKGROUND: Characteristics and outcomes of patients with takotsubo syndrome remain to be defined. The goal of this study was to report the characteristics and long-term outcomes of patients presenting with takotsubo syndrome compared with other patients presenting with acute myocardial infarction (AMI) in a community-based population. METHODS: This retrospective population-based study included patients hospitalised for AMI from 2006 to 2016. Those patients with takotsubo syndrome were compared with the patients with AMI. The primary outcome was all-cause mortality. Matching was performed to assemble a cohort of patients with similar baseline characteristics. RESULTS: Among 26,015 patients hospitalised with an initial diagnosis of AMI, 530 (2.0%) were diagnosed with takotsubo syndrome. Patients with takotsubo syndrome were older (68.3 ± 11.3 vs 65.6 ± 12.2 years) and more likely to be women (93.4% vs 30.7%). Concomitant hypothyroidism, rheumatologic disorders, and lung disease were more prevalent in the takotsubo syndrome group, whereas diabetes and hyperlipidemia were less prevalent. Mortality was lower in the takotsubo syndrome group (1-year mortality 4.0% vs 8.9%; P < 0.001). The 530 patients with takotsubo syndrome were matched with 1,315 AMI patients with similar baseline characteristics. At a follow-up of 5.4 ± 3.3 years, patients with takotsubo syndrome had a lower risk for all-cause death than other patients who presented with AMI (hazard ratio 0.59, 95% CI 0.47-0.76). CONCLUSIONS: Among patients presenting with AMI, patients with takotsubo syndrome were older and more likely to be women. Patients with takotsubo syndrome had better long-term outcomes compared with matched AMI patients.

Isotretinoin and Risk of Cardiovascular Events in Adults with Acne: A Population-based Retrospective Cohort Study.

BACKGROUND: Case reports have suggested isotretinoin exposure may be associated with adverse cardiac events. There are limited data where the cardiovascular safety of isotretinoin is systematically evaluated. OBJECTIVE: The aim of this study was to determine the strength of association between isotretinoin exposure and adverse cardiovascular events. METHODS: This was a population-based retrospective cohort study within an integrated healthcare delivery system. Adults ≥ 18 years of age with acne between 2009 and 2018 were included. Exposure to isotretinoin was identified using pharmacy records, and propensity score 1:1 matching was performed. The primary outcome was a composite of cardiovascular outcomes, including acute myocardial infarction, heart failure, and all-cause death. RESULTS: The cohort consisted of 12,140 adults (10.5%) exposed to isotretinoin and 103,126 adults who were never exposed. Mean follow-up was 7.1 ± 2.9 years. After propensity score 1:1 matching, 23,844 patients were included. The rates of the composite cardiovascular outcomes were 0.47 versus 0.48 per 1000 person-years in the isotretinoin and non-exposed groups, respectively. No significant association was observed between isotretinoin treatment and the composite cardiovascular outcomes (adjusted hazard ratio [HR] 0.99, 95% confidence interval [CI] 0.62-1.58), all-cause mortality (adjusted HR 1.10, 95% CI 0.62-1.95), acute myocardial infarction (adjusted HR 1.00, 95% CI 0.33-3.09), congestive heart failure (adjusted HR 0.45, 95% CI 0.14-1.40), or atrial fibrillation (adjusted HR 0.44, 95% CI 0.12-1.65). CONCLUSIONS: Among adult patients with acne, no association was found between exposure to isotretinoin and an increased risk of cardiovascular events. Physicians should not be discouraged from prescribing isotretinoin out of concern for cardiovascular effects.

Effect of Using an Age-adjusted D-dimer to Assess for Pulmonary Embolism in Community Emergency Departments.

BACKGROUND: The objective of this study was to evaluate the effect of changing the laboratory-reported D-dimer reference intervals to age-adjusted reference intervals on the use of advanced chest imaging and 30-day adverse events among emergency department (ED) encounters. METHODS: A retrospective interrupted time-series analysis of ED encounters for patients > 50 years evaluated for suspected pulmonary embolism (PE) from April 2014 to April 2016. The primary outcome was use of advanced diagnostic imaging, and the secondary outcome was 30-day mortality or PE diagnosis. Secondary analyses also quantified delayed PE diagnoses pre- and postintervention. A generalized estimating equation segmented logistic regression model, adjusting for patient and facility characteristics, was used to determine changes in odds of diagnostic imaging and 30-day mortality or PE diagnoses. RESULTS: A total of 10,534 (5,153 pre- and 5,381 postimplementation) ED encounters were included. Advanced imaging was obtained in 35.9% of pre- versus 33% of postimplementation encounters. Age-adjusted D-dimer (AADD) showed a small and nonsignificant decrease in month-to-month trends of advanced chest imaging postimplementation (odds ratio [OR] = 0.98, 95% confidence interval [CI] = 0.96 to 1.00). Use of advanced imaging in patients with D-dimer values lower than 500 ng/mL fibrinogen-equivalent units (FEU) was similar in the preintervention (5.8%) and postintervention (6.8%) periods. However, imaging was obtained in 30% of patients postintervention with a D-dimer result less than AADD reference interval , but more than the historical 500 ng/mL FEU reference interval. Implementing an AADD threshold demonstrated no change in the rate of 30-day adverse events (missed PE or mortality). CONCLUSION: Changing the laboratory-reported D-dimer reference intervals for evaluation of PE was not associated with reduction in advanced chest imaging and did not increase 30-day adverse events. However, there was substantial noncompliance with the age-adjusted reference intervals in the postintervention period likely blunting the impact of this intervention.

Risk of Acute Myocardial Infarction, Heart Failure, and Death in Migraine Patients Treated with Triptans.

OBJECTIVE: The goal of this study is to determine the strength of association between treatment with triptans and acute myocardial infarction, heart failure, and death. BACKGROUND: Case reports in the literature have raised concerns over an association between treatment of migraine headaches with triptans and cardiovascular events. This study aims to systematically evaluate this association in a contemporary population-based cohort. We hypothesized that triptan exposure is not associated with increased cardiovascular events. METHODS: A retrospective cohort study was conducted within an integrated healthcare delivery system in Southern California. From January 2009 to December 2018, 189,684 patients age ≥18 years had a diagnosis of migraine. In this group, 130,656 were exposed to triptans. Patients treated with triptans were matched 1:1 to those not exposed to triptans by using a propensity score. The primary outcome was acute myocardial infarction; secondary outcomes were heart failure, all-cause death, and combined acute myocardial infarction, heart failure, and death. RESULTS: The incidence rate of acute myocardial infarction was 0.67 per 1000 person-year in triptan-exposed vs 1.44 per 1000 person-year in not exposed patients. In propensity-matched analyses, the adjusted hazard ratio for triptan exposure was 0.95 (95% confidence interval [CI] 0.84-1.08) for acute myocardial infarction; 1.00 (95% CI 0.93-1.08) for all-cause death; 0.93 (95% CI 0.81-1.08) for heart failure; and 0.99 (95% CI 0.93-1.06) for a composite of acute myocardial infarction, heart failure, or death. Sensitivity analyses focusing on stratified subgroups based on age, gender, ethnicity, and several cardiac risk factors also revealed no significant association between triptan exposure and cardiovascular events. CONCLUSIONS: No association was found between exposure to triptans and an increased risk of cardiovascular events. These data provide reassurance regarding the cardiovascular safety of utilizing triptans for the medical management of migraine headaches.

Revascularization Versus Medical Therapy in Patients Aged 80 Years and Older with Acute Myocardial Infarction.

BACKGROUND/OBJECTIVES: Older patients are underrepresented in acute coronary syndrome clinical trials. We sought to evaluate the benefits of revascularization in patients aged 80 years and older presenting with acute myocardial infarction (AMI). DESIGN: Retrospective study utilizing inverse probability of treatment weighting (IPTW). SETTING: Single tertiary referral center for an integrated healthcare system in southern California. PARTICIPANTS: Patients undergoing invasive coronary angiography for AMI between 2009 and 2019, and subsequently treated with percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG), or medical therapy alone. MEASUREMENTS: All-cause mortality, nonfatal myocardial infarction (MI), and repeated revascularization. RESULTS: A total of 1,433 patients aged 80 years or older (median age = 83.5 years; 66% male) presenting with AMI who underwent treatment with PCI (50%), CABG (12%), or medical therapy alone (38%) were included. Those treated with medical therapy were more likely to be Black, had one or more chronic total occlusions in any vessel, had more comorbidities, and had lower left ventricular ejection fraction. Baseline characteristics were well balanced after IPTW adjustment. Median follow-up was 2.6 years. Revascularization (PCI or CABG) was associated with reduced mortality (hazard ratio (HR) = 0.66; 95% confidence interval (CI) = 0.60-0.73) and nonfatal MI (HR = 0.68; 95% CI = 0.58-0.78), but an increased need for repeated revascularization (HR = 1.60; 95% CI = 1.15-2.23). Separately comparing PCI or CABG alone versus medical therapy yielded similar results. Revascularization was associated with lower mortality in all subgroups, except in Black patients and those with prior CABG. CONCLUSION: Revascularization is superior to medical therapy in reducing all-cause mortality and nonfatal MI in patients aged 80 years and older with AMI. Age alone should not preclude patients from potentially beneficial invasive therapies.

Antiviral anticoagulation.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel envelope virus that causes coronavirus disease 2019 (COVID-19). Hallmarks of COVID-19 are a puzzling form of thrombophilia that has elevated D-dimer but only modest effects on other parameters of coagulopathy. This is combined with severe inflammation, often leading to acute respiratory distress and possible lethality. Coagulopathy and inflammation are interconnected by the transmembrane receptor, tissue factor (TF), which initiates blood clotting as a cofactor for factor VIIa (FVIIa)-mediated factor Xa (FXa) generation. TF also functions from within the nascent TF/FVIIa/FXa complex to trigger profound changes via protease-activated receptors (PARs) in many cell types, including SARS-CoV-2-trophic cells. Therefore, aberrant expression of TF may be the underlying basis of COVID-19 symptoms. Evidence suggests a correlation between infection with many virus types and development of clotting-related symptoms, ranging from heart disease to bleeding, depending on the virus. Since numerous cell types express TF and can act as sites for virus replication, a model envelope virus, herpes simplex virus type 1 (HSV1), has been used to investigate the uptake of TF into the envelope. Indeed, HSV1 and other viruses harbor surface TF antigen, which retains clotting and PAR signaling function. Strikingly, envelope TF is essential for HSV1 infection in mice, and the FXa-directed oral anticoagulant apixaban had remarkable antiviral efficacy. SARS-CoV-2 replicates in TF-bearing epithelial and endothelial cells and may stimulate and integrate host cell TF, like HSV1 and other known coagulopathic viruses. Combined with this possibility, the features of COVID-19 suggest that it is a TFopathy, and the TF/FVIIa/FXa complex is a feasible therapeutic target.

Coagulation factor VIIa binds to herpes simplex virus 1-encoded glycoprotein C forming a factor X-enhanced tenase complex oriented on membranes.

BACKGROUND: The cell membrane-derived initiators of coagulation, tissue factor (TF) and anionic phospholipid (aPL), are constitutive on the herpes simplex virus type 1 (HSV1) surface, bypassing physiological regulation. TF and aPL accelerate proteolytic activation of factor (F) X to FXa by FVIIa to induce clot formation and cell signaling. Thus, infection in vivo is enhanced by virus surface TF. HSV1-encoded glycoprotein C (gC) is implicated in this tenase activity by providing viral FX binding sites and increasing FVIIa function in solution. OBJECTIVE: To examine the biochemical influences of gC on FVIIa-dependent FX activation. METHODS: Immunogold electron microscopy (IEM), kinetic chromogenic assays and microscale thermophoresis were used to dissect tenase biochemistry. Recombinant TF and gC were solubilized (s) by substituting the transmembrane domain with poly-histidine, which could be orientated on synthetic unilamellar vesicles containing Ni-chelating lipid (Ni-aPL). These constructs were compared to purified HSV1 TF±/gC ± variants. RESULTS: IEM confirmed that gC, TF, and aPL are simultaneously expressed on a single HSV1 particle where the contribution of gC to tenase activity required the availability of viral TF. Unlike viral tenase activity, the cofactor effects of sTF and sgC on FVIIa was additive when bound to Ni-aPL. FVIIa was found to bind to sgC and this was enhanced by FX. Orientation of sgC on a lipid membrane was critical for FVIIa-dependent FX activation. CONCLUSIONS: The assembly of gC with FVIIa/FX parallels that of TF and may involve other constituents on the HSV1 envelope with implications in virus infection and pathology.

Impact of Physician-Patient Language Concordance on Patient Outcomes and Adherence to Clinical Chest Pain Recommendations.

OBJECTIVES: The objective was to evaluate if there is an association between patient-physician language concordance and adverse patient outcomes or physician adherence to clinical recommendations for emergency department (ED) patients with chest pain. METHODS: We conducted a retrospective observational study of adult ED chest pain encounters with a troponin order from May 2016 to September 2017 across 15 community EDs. Outcomes were 30-day acute myocardial infarction or all-cause mortality, hospital admission/observation, or noninvasive cardiac testing. To assess patient outcomes, we used the overall cohort. To assess adherence to clinical recommendations, we used a subgroup of patients with a low-risk HEART score. A mixed-effects logistic regression model was used to compare the odds of the outcomes between language concordant and discordant patient-physician pairs, controlling for patient characteristics. RESULTS: Overall, 52,014 ED encounters were included (10,791 low-risk HEART encounters). Of those 6,452 (12.4%) encounters were language discordant and 1.7% in each group had an adverse outcome. Adjusted models demonstrated no increased risk for language discordant ED encounters when comparing adverse outcomes (odds ratio [OR] = 0.96, 95% confidence interval [CI] = 0.6 to 1.5) for all patients or recommended care (OR = 1.02, 95% CI = 0.87 to 1.2) for low-risk patients. CONCLUSIONS: No associations were found between patient-physician language concordance and outcomes or physician adherence to clinical recommendations for ED patients with chest pain. Accessible and effective interpretation services, combined with a decision support tool with standard clinical recommendations, may have contributed to equitable care.

Blood coagulation dissected.

Hemostasis is the physiological control of bleeding and is initiated by subendothelial exposure. Platelets form the primary vascular seal in three stages (localization, stimulation and aggregation), which are triggered by specific interactions between platelet surface receptors and constituents of the subendothelial matrix. As a secondary hemostatic plug, fibrin clot formation is initiated and feedback-amplified to advance the seal and stabilize platelet aggregates comprising the primary plug. Once blood leakage has been halted, the fibrinolytic pathway is initiated to dissolve the clot and restore normal blood flow. Constitutive and induced anticoagulant and antifibrinolytic pathways create a physiological balance between too much and too little clot production. Hemostatic imbalance is a major burden to global healthcare, resulting in thrombosis or hemorrhage.

Cyclophilin C-associated protein/Mac-2 binding protein colocalizes with calnexin and regulates the expression of tissue transglutaminase.

Cyclophilin C-associated protein (CyCAP) or Mac-2 binding protein has been identified as a binding protein for cyclophilin C in mice and for Mac-2 (galectin-3) in human, suggesting its multiple binding activity to proteins. In the present study, using specific anti-rat-CyCAP antibody, we found that CyCAP colocalizes with calnexin at the location near the nuclear envelope, however CyCAP does not have colocalization with calreticulin. In senescent fibroblasts and interferon-gamma (IFNgamma) treated fibroblasts, both calnexin and CyCAP form larger polymers and are released from the endoplasmic reticulum (ER) through the cellular membrane to the extracellular area. Immunoprecipitation studies further confirm that the release of calnexin is through binding to CyCAP. Further, we found that tissue transglutaminase (tTG) protein is decreased, however not at the RNA level, in CyCAP null fibroblasts, which suggests that CyCAP is involved in tTG post-translational modification. Our data give novel evidence that CyCAP regulates the post-translational modification of tTG through its colocalization with calnexin in ER.

Delivery of four-dimensional radiotherapy with TrackBeam for moving target using an AccuKnife dual-layer MLC: dynamic phantoms study.

Respiratory motion has been considered a clinical challenge for lung tumor treatments due to target motion. In this study, we aimed to perform an experimental evaluation based on dynamic phantoms using MLC-based beam tracking. TrackBeam, a prototype real-time beam tracking system, has been assembled and evaluated in our clinic. TrackBeam includes an orthogonal dual-layer micro multi-leaf collimator (DmMLC), an on-board mega-voltage (MV) portal imaging device, and an image processing workstation. With a fiducial marker implanted in a moving target, the on-board imaging device can capture the motion. The TrackBeam workstation processes the online MV fluence and detects and predicts tumor motion. The DmMLC system then dynamically repositions each leaf to form new beam apertures based on the movement of the fiducial marker. In this study, a dynamic phantom was used for the measurements. Three delivery patterns were evaluated for dosimetric verification based on radiographic films: no-motion-lung-tumor (NMLT), three-dimensional conformal radiotherapy (3DCRT), and four-dimensional tracking radiotherapy (4DTRT). The displacement between the DmMLC dynamic beam isocenter and the fiducial marker was in the range of 0.5 mm to 1.5 mm. With radiographic film analysis, the planar dose histogram difference between 3DCRT and NLMT was 48.6% and 38.0% with dose difference tolerances of 10% and 20%. The planar dose histogram difference between 4DTRT and NLMT was 15.2% and 4.0% respectively. Based-on dose volume histogram analysis, 4DTRT reduces the mean dose for the surrounding tissue from 35.4 Gy to 19.5 Gy, reduces the relative volume of the total lung from 28% to 18% at V20, and reduces the amount of dose from 35.2 Gy to 15.0 Gy at D20. The experimental results show that MLC-based real-time beam tracking delivery provides a potential solution to respiratory motion control. Beam tracking delivers a highly conformal dose to a moving target, while sparing surrounding normal tissue.

Unmasking of epigenetically silenced genes reveals DNA promoter methylation and reduced expression of PTCH in breast cancer.

A pharmacological-based global screen for epigenetically silenced tumor suppressor genes was performed in MCF-7 and MDA-MB-231 breast cancer cells. Eighty-one genes in MCF-7 cells and 131 in MDA-MB-231 cells were identified, that had low basal expression and were significantly upregulated following treatment. Eighteen genes were studied for methylation and/or expression in breast cancer; PTCH, the receptor for the hedgehog (Hh) pathway and a known tumor suppressor gene, was selected for further analysis. Methylation of the PTCH promoter was found in MCF-7 cells and in breast cancer samples, and correlated with low PTCH expression. Immunohistochemical analysis of breast tissue arrays revealed high expression of PTCH in normal breast compared to ductal carcinomas in situ (DCIS) and invasive ductal carcinomas; furthermore, association was found between PTCH expression and favorable prognostic factors. PTCH is an inhibitor of the Hh pathway, and its silencing activates the pathway and promotes growth. Indeed, high activity of the Hh pathway was identified in MCF-7 cells and overexpression of PTCH inhibited the pathway. Moreover, treatment with cyclopamine, an inhibitor of the pathway, reduced cell growth and slowed the cell cycle in these cells. Thus, unmasking of epigenetic silencing in breast cancer enabled us to discover a large number of candidate tumor suppressor genes. Further analysis suggested a role of one of these genes, PTCH, in breast cancer tumorigenesis.

15-hydroxyprostaglandin dehydrogenase is a tumor suppressor of human breast cancer.

Prostaglandin E(2) plays a growth-stimulatory role in breast cancer, and the rate-limiting enzyme in its synthesis, cyclooxygenase-2, is often overexpressed in these cancers. Little is known about the role of the key prostaglandin catabolic enzyme 15-hydroxyprostaglandin dehydrogenase (15-PGDH) in breast cancer pathogenesis. Using a pharmacologically based screen for epigenetically silenced genes, we found low levels of 15-PGDH in MDA-MB-231 cells [estrogen receptor (ER) negative] but high levels in MCF-7 cells (ER positive) and observed its up-regulation following demethylation treatment. Further analysis revealed methylation of the 15-PGDH promoter in one breast cancer cell line and 30% of primary tumors. Analysis of 15-PGDH expression revealed low levels in 40% of primary breast tumors and identified a correlation between 15-PGDH and ER expression. Transfection assays showed that transient up-regulation of 15-PGDH levels in MDA-MB-231 cells resulted in a decreased clonal growth, and stable up-regulation significantly decreased the ability of these cells to form tumors in athymic mice. In contrast, transient silencing of 15-PGDH in MCF-7 cells resulted in their enhanced proliferation, and a stable silencing in these cells enhanced cell cycle entry in vitro and tumorigenicity in vivo. Forced expression of 15-PGDH inhibited the ER pathway and silencing of 15-PGDH up-regulated expression of aromatase. In addition, 15-PGDH levels were down-regulated by estrogen but up-regulated by the tumor suppressor gene CAAT/enhancer binding protein alpha. Our results indicate for the first time that 15-PGDH may be a novel tumor suppressor gene in breast cancer, and suggest that this enzyme can modulate the ER pathway.