SDPR functions as a metastasis suppressor in breast cancer by promoting apoptosis

Metastatic dissemination of breast cancer cells represents a significant clinical obstacle to curative therapy. The loss of function of metastasis suppressor genes is a major rate-limiting step in breast cancer progression that prevents the formation of new colonies at distal sites. However, the discovery of new metastasis suppressor genes in breast cancer using genomic efforts has been slow, potentially due to their primary regulation by epigenetic mechanisms. Here, we report the use of model cell lines with the same genetic lineage for the identification of a novel metastasis suppressor gene, serum deprivation response (SDPR), localized to 2q32-33, a region reported to be associated with significant loss of heterozygosity in breast cancer. In silico metaanalysis of publicly available gene expression datasets suggests that the loss of expression of SDPR correlates with significantly reduced distant-metastasis–free and relapse-free survival of breast cancer patients who underwent therapy. Furthermore, we found that stable SDPR overexpression in highly metastatic breast cancer model cell lines inhibited prosurvival pathways, shifted the balance of Bcl-2 family proteins in favor of apoptosis, and decreased migration and intravasation/extravasation potential, with a corresponding drastic suppression of metastatic nodule formation in the lungs of NOD/SCID mice. Moreover, SDPR expression is silenced by promoter DNA methylation, and as such it exemplifies epigenetic regulation of metastatic breast cancer progression. These observations highlight SDPR as a potential prognostic biomarker and a target for future therapeutic applications.The metastatic progression of breast cancer accounts for the majority of disease-related mortality. A major rate-limiting step in metastasis is the loss of function of the metastasis suppressor genes, which block a cascade of crucial steps including the loss of adhesion of primary tumor cells, intravasation into the blood and lymphatics with subsequent extravasation at distant sites, and the formation of new colonies. Despite the identification of the first metastasis suppressor gene, nonmetastatic 23 (NM23), nearly two decades ago (1), only a handful of new metastasis suppressors have been identified in recent years using candidate gene approaches (2, 3). It is likely that the current catalog of metastasis suppressor genes remains incomplete despite the vast sequencing efforts due to the possibility that a subset of genes regulated by epigenetic mechanisms may have eluded traditional discovery procedures (4–6). To identify these elusive metastasis suppressor genes, which are functionally compromised in late-stage disease (7–9), we took advantage of a well-established breast cancer progression cell line model system sharing the same genetic linage (Fig. 1A) (10). This model system consists of five cell lines that represent the various stages of breast cancer progression based on the MCF10A cell line: MCF10AneoT (NeoT), MCF10AT1Kcl2 (MII), MCF10CA1h (MIII), and MCF10CA1a (MIV). NeoT cells were generated by overexpression of HRAS in MCF10A cells and rarely exhibit growth following injection into nude mice. MII cells were generated by single xenograft passaging of NeoT cells. When injected subcutaneously (s.c.) into nude mice, MII cells generally form benign tumors that progress to carcinoma one out of four times; hence they mimic the early stage, carcinoma in situ. MIII and MIV cells were isolated from tumors formed by MII cells. MIII cells represent carcinoma, as in general they metastasize at a very low frequency, which requires a prolonged incubation period. On the other hand, MIV cells have the potential to readily seed lung metastases and represent the final stages of a breast cancer, metastatic carcinoma. We compared the gene expression profiles of these latter three model cell lines and leveraged large amounts of publically available breast tumor gene expression profiling data (11–13) by applying multiple bioinformatics filters to identify candidate metastasis suppressor genes.Open in a separate windowFig. 1.Identification of SDPR as a candidate metastasis suppressor gene. (A) Schematic depiction of the generation of breast cancer progression cell line model system. The model consists of five cell lines representing different stages of breast cancer progression. MI, normal breast epithelial cells; NeoT and MII, carcinoma in situ; MIII, carcinoma; and MIV, metastatic carcinoma. (B) Hierarchical clustering of gene expression profiles from MII, MIII, and MIV cells for the genes whose expression differ at least twofold between each cell line. Two clusters, cluster 6 and 7, are magnified because expressions of the genes in these two clusters are significantly suppressed in metastatic MIV cells compared with nonmetastatic MII and MIII. (C) The schematic summary of our strategy for the selection of SDPR as the top candidate metastasis suppressor.Here, we report the discovery of the phosphatidylserine-interacting protein, serum deprivation response (SDPR) (also known as cavin-2), as a bona fide metastasis suppressor. Thus far, studies on SDPR function have been limited to its role as a regulator of caveolae formation (14), and its potential direct involvement in cancer has not been previously described. However, it has been reported that SDPR expression is down-regulated significantly in not only breast cancer but also in cancers of kidney and prostate (15). Moreover, SDPR protein down-regulation was observed in serum from patients with malignant kidney tumors, and hence it was suggested as a possible diagnostic marker to discriminate malignant tumors from benign formations (16). Interestingly, SDPR is localized to 2q32-33, a region with a significant level of loss of heterozygosity that is associated with a high degree of recurrence in breast cancer (17, 18). Our results indicate that SDPR is capable of specifically inhibiting the metastatic growth of breast cancer cells.     

Associations between retinal microvascular structure and the severity and extent of coronary artery disease

Objective

Microvascular mechanisms are increasingly recognized as being involved in a significant proportion of coronary artery disease (CAD) cases, but their exact contribution or role is unclear. We aimed to define the association between retinal microvascular signs and both CAD extent and severity.

Methods

1120 participants of the Australian Heart Eye Study were included. Retinal vessel caliber was measured from digital retinal images. Extent and severity of CAD was assessed using several approaches. First, a simple scoring classifying participants as having one-vessel, two-vessel, and three-vessel disease was used. Gensini and Extent scores were calculated using angiography findings.

Results

After multivariable adjustment, significantly narrower retinal arteriolar caliber in women (comparing lowest versus highest quartile or reference) and wider venular caliber in men (comparing highest versus lowest quartile or reference) were associated with 2-fold and 54% higher odds of having at least one stenosis ≥50% in the epicardial coronary arteries, respectively. Women in the third versus first tertile of retinal venular caliber had 92% and ∼2-fold higher likelihood of having higher Gensini and Extent scores, respectively. Women in the lowest versus highest tertile of retinal arteriolar caliber had greater odds of having higher Extent scores, OR 2.99 (95% CI 1.45–6.16). In men, non-significant associations were observed between retinal vascular caliber and Gensini and Extent scores.

Conclusions

An unhealthy retinal microvascular profile, namely, narrower retinal arterioles and wider venules was associated with more diffuse and severe CAD among women.     

Genetics and Epigenetics in Major Psychiatric Disorders

No specific gene has been identified for any major psychiatric disorder, including schizophrenia, in spite of strong evidence supporting a genetic basis for these complex and devastating disorders. There are several likely reasons for this failure, ranging from poor study design with low statistical power to genetic mechanisms such as polygenic inheritance, epigenetic interactions, and pleiotropy. Most study designs currently in use are inadequate to uncover these mechanisms. However, to date, genetic studies have provided some valuable insight into the causes and potential therapies for psychiatric disorders. There is a growing body of evidence suggesting that the understanding of the genetic etiology of psychiatric illnesses, including schizophrenia, will be more successful with integrative approaches considering both genetic and epigenetic factors. For example, several genes including those encoding dopamine receptors (DRD2, DRD3, and DRD4), serotonin receptor 2A (HTR2A) and catechol-O-methyltransferase (COMT) have been implicated in the etiology of schizophrenia and related disorders through meta-analyses and large, multicenter studies. There is also growing evidence for the role of DRD1, NMDA receptor genes (GRIN1, GRIN2A, GRIN2B), brain-derived neurotrophic factor (BDNF), and dopamine transporter (SLC6A3) in both schizophrenia and bipolar disorder. Recent studies have indicated that epigenetic modification of reelin (RELN), BDNF, and the DRD2 promoters confer susceptibility to clinical psychiatric conditions. Pharmacologic therapy of psychiatric disorders will likely be more effective once the molecular pathogenesis is known. For example, the hypoactive alleles of DRD2 and the hyperactive alleles of COMT, which degrade the dopamine in the synaptic cleft, are associated with schizophrenia. It is likely that insufficient dopaminergic transmission in the frontal lobe plays a role in the development of negative symptoms associated with this disorder. Antipsychotic therapies with a partial dopamine D2 receptor agonist effect may be a plausible alternative to current therapies, and would be effective in symptom reduction in psychotic individuals. It is also possible that therapies employing dopamine D1/D2 receptor agonists or COMT inhibitors will be beneficial for patients with negative symptoms in schizophrenia and bipolar disorder. The complex etiology of schizophrenia, and other psychiatric disorders, warrants the consideration of both genetic and epigenetic systems and the careful design of experiments to illumine the genetic mechanisms conferring liability for these disorders and the benefit of existing and new therapies.     

Orbital apex syndrome secondary to Pseudallescheria boydii fungal sinusitis in an immunocompetent patient

Orbital apex syndrome secondary to mucormycosis in immuno-compromised patients is well described; however, few reports exist of a paranasal sinus mycetoma resulting in this presentation in the immuno-competent patient. The case is reported of a 92-year-old man who developed orbital apex syndrome secondary to a sphenoidal sinus mycetoma of Pseudallescheria boydii.     

Loss of heterozygosity as a predictor to map tumor suppressor genes in cancer: molecular basis of its occurrence.

High frequency of chromosomal deletions elicited as losses of heterozygosity is a hallmark of genomic instability in cancer. Functional losses of tumor suppressor genes caused by loss of heterozygosity at defined regions during clonal selection for growth advantage define the minimally lost regions as their likely locations on chromosomes. Loss of heterozygosity is elicited at the molecular or cytogenetic level as a deletion, a gene conversion, single or double homologous and nonhomologous mitotic recombinations, a translocation, chromosome breakage and loss, chromosomal fusion or telomeric end-to-end fusions, or whole chromosome loss with or without accompanying duplication of the retained chromosome. Because of the high level of specificity, loss of heterozygosity has recently become invaluable as a marker for diagnosis and prognosis of cancer. The molecular defects for the occurrence of loss of heterozygosity are derived from disabled caretaker genes, which protect the integrity of DNA, or chromosome segregator genes, which mediate faithful chromosome disjunction.     

Catheter intramural needle radiofrequency ablation creates deeper lesions than irrigated tip catheter ablation

Radiofrequency ablation of the left ventricle using an endocardially placed electrode is unable to reliably create transmural lesions even with active electrode cooling. To produce deeper radiofrequency lesions, the authors developed and tested a prototype intramural needle ablation catheter that had a distal 1.1-mm diameter straight needle that could be advanced 12 mm into the myocardium. Freshly excised hearts from eight male sheep were perfused and superfused with oxygenated ovine blood. Ablations were performed for 60 seconds with the prototype catheter and a conventional 5-mm irrigated tip ablation catheter at target temperatures of 90 degrees C and 50 degrees C, respectively. The ablation lesions were bisected and stained with blue tetrazolium to assess lesion geometry. The irrigated tip ablation catheter required significantly more power than the intramural needle ablation catheter (37.7 +/- 7.3 vs 6.4 +/- 2.1 W, P < 0.01). Intramural needle lesions were significantly deeper (12.5 +/- 3.0 mm vs 8.3 +/- 2.1 mm, P < 0.01) but less wide (3.9 +/- 1.1 mm vs 11.5 +/- 2.0 mm, P < 0.01) than irrigated tip lesions. There was a high incidence of crater formation (74%), popping (45%), and myocardial charring (29%) during irrigated tip ablation; these phenomena were not observed during intramural needle ablation. The intramural needle ablation catheter creates significantly deeper but narrower lesions without evidence of tissue boiling. This technology may be particularly useful for ablation of ventricular tachycardia originating from regions where tissue depth is increased, like the ventricular septum.     

Aberrant activation of gamma-catenin promotes genomic instability and oncogenic effects during tumor progression

Gamma-catenin (plakoglobin) exists in cells either as a component of adherens junctions, along with beta-catenin and alpha-catenin, or in association with desmoplakin in desmosomes, which are in turn coupled to the cytoskeleton linking to the plasma membrane. Although gamma-catenin overexpression is observed in many cancers, the molecular basis of its contribution to tumor progression remains unclear. In this study, we examined gamma-catenin overexpression-mediated effects leading to altered regulation of effector genes such as PTTG and c-Myc, as well as differential activation of signaling pathways. We found that overexpression of gamma-catenin caused: (1) a reduction in E-cadherin and corresponding increase in vimentin levels concomitant with increased cell mobility and migration; (2) enhancement in the levels of phosphorylated Akt and Erk in the presence of EGF and (3) an increase in PTTG and c-Myc protein levels, which are likely to accelerate chromosomal instability and uncontrolled proliferation, respectively, in the affected cells. These effects resulting from overexpression of gamma-catenin were further validated in converse experiments with the aid of siRNA knockdown of the endogenous gamma-catenin gene. In conclusion, our studies provide a molecular basis for the promotion of genomic instability and the oncogenic effects due to overexpression of gamma-catenin in human cancer.     

Combined ventricular endocardial and epicardial substrate mapping using a sonomicrometry-based electroanatomical mapping system

BACKGROUND: Substrate mapping using a magnetic electroanatomical mapping system (MEAM) has been shown to accurately delineate the location/extent of scarred myocardium. This study examined the ability of a sonomicrometry-based electroanatomic mapping system (SEAM) to render endocardial and epicardial substrate maps of infarcted ventricular myocardium. METHODS AND RESULTS: In 7 swine with healed myocardial infarctions, combined epicardial and endocardial left ventricular (LV) substrate maps were created with both SEAM and MEAM mapping systems using 246+/-68 and 244+/-44 points respectively. Scarred myocardium was identified based upon bipolar electrogram amplitude < 1.5 mV, and radiofrequency ablation lesions were delivered to the scar border as defined by the sonomicrometry mapping system. The LV endocardial chamber volume as defined by SEAM (125+/-46 ml) correlated well with that defined by the MEAM (137+/-45 ml, r=0.77, p < 0.05). The area of infarcted tissue as determined by SEAM was highly correlated with that determined by gross pathology (r=0.96 for endocardial scar and r=0.92 for epicardial scar p < 0.05). The scar area calculated by the SEAM system also correlated well with the scar area determined by the MEAM system (0.91 for endocardial scar and 0.90 for epicardial scar p < 0.05). Finally, the sonomicrometry-based system was able to guide the placement of radiofrequency ablation lesions to the borders of the scar. CONCLUSIONS: This study demonstrates that the sonomicrometry-based mapping can accurately reconstruct three-dimensional voltage maps of the endocardial and epicardial ventricular surfaces and guide the placement of ablation lesions along the scar border zone.