Hypoxia-mediated repression of pyruvate carboxylase drives immunosuppression.

BACKGROUND: Metabolic plasticity mediates breast cancer survival, growth, and immune evasion during metastasis. However, how tumor cell metabolism is influenced by and feeds back to regulate breast cancer progression are not fully understood. We identify hypoxia-mediated suppression of pyruvate carboxylase (PC), and subsequent induction of lactate production, as a metabolic regulator of immunosuppression. METHODS: We used qPCR, immunoblot, and reporter assays to characterize repression of PC in hypoxic primary tumors. Steady state metabolomics were used to identify changes in metabolite pools upon PC depletion. In vivo tumor growth and metastasis assays were used to evaluate the impact of PC manipulation and pharmacologic inhibition of lactate transporters. Immunohistochemistry, flow cytometry, and global gene expression analyzes of tumor tissue were employed to characterize the impact of PC depletion on tumor immunity. RESULTS: PC is essential for metastatic colonization of the lungs. In contrast, depletion of PC in tumor cells promotes primary tumor growth. This effect was only observed in immune competent animals, supporting the hypothesis that repression of PC can suppress anti-tumor immunity. Exploring key differences between the pulmonary and mammary environments, we demonstrate that hypoxia potently downregulated PC. In the absence of PC, tumor cells produce more lactate and undergo less oxidative phosphorylation. Inhibition of lactate metabolism was sufficient to restore T cell populations to PC-depleted mammary tumors. CONCLUSIONS: We present a dimorphic role for PC in primary mammary tumors vs. pulmonary metastases. These findings highlight a key contextual role for PC-directed lactate production as a metabolic nexus connecting hypoxia and antitumor immunity.

Enantioselective Synthesis of Chiral Cyclopent-2-enones by Nickel-Catalyzed Desymmetrization of Malonate Esters.

The enantioselective synthesis of highly functionalized chiral cyclopent-2-enones by the reaction of alkynyl malonate esters with arylboronic acids is described. These desymmetrizing arylative cyclizations are catalyzed by a chiral phosphinooxazoline/nickel complex, and cyclization is enabled by the reversible E/Z isomerization of alkenylnickel species. The general methodology is also applicable to the synthesis of 1,6-dihydropyridin-3(2H)-ones.

Association between Diverticular Disease and Pre-Neoplastic Colorectal Lesions in an Urban African-American Population.

BACKGROUND: It is unclear whether there is a shared pathway in the development of diverticular disease (DD) and potentially neoplastic colorectal lesions since both diseases are found in similar age groups and populations. AIM: To determine the association between DD and colorectal pre-neoplastic lesions in an African-American urban population. METHODS: Data from 1986 patients who underwent colonoscopy at the Howard University Hospital from January 2012 through December 2012 were analyzed for this study. The presence of diverticula and polyps was recorded using colonoscopy reports. Polyps were further classified into adenoma or hyperplastic polyp based on histopathology reports. Multiple logistic regression was done to analyze the association between DD and colonic lesions. RESULTS: Of the 1986 study subjects, 1,119 (56%) were females, 35% had DD and 56% had at least one polyp. There was a higher prevalence of polyps (70 vs. 49%; OR = 2.3; 95% CI: 1.9-2.8) and adenoma (43 vs. 25%; OR = 2.0; 95% CI: 1.7-2.5) in the diverticular vs. non-diverticula patients. Among patients who underwent screening colonoscopy, the presence of diverticulosis was associated with increased odds of associated polyps (OR = 9.9; 95% CI: 5.4-16.8) and adenoma (OR = 5.1; 95% CI: 3.4-7.8). CONCLUSION: Patients with DD are more likely to harbor colorectal lesions. These findings call for more vigilance on the part of endoscopists during colonoscopy in patients known to harbor colonic diverticula.

Prevalence of colorectal neoplasia among young African Americans and Hispanic Americans.

BACKGROUND: The disproportionately higher incidence of and mortality from colorectal cancer (CRC) among African Americans (AA) led the American College of Gastroenterology to recommend screening starting at age 45 in 2005. AIM: The purpose of this study was to determine the prevalence of colorectal neoplasia among 40-49-year-old inner city AA and Hispanic Americans (HA). METHODS: We reviewed the medical records of 2,435 inner city AA and HA who underwent colonoscopy regardless of indication and compared the prevalence of colorectal neoplasia between AA and HA patients. We used logistic regression models to calculate odds ratios (OR) and 95 % confidence intervals (CI). RESULTS: There were 2,163 AAs and 272 HA. There were 57 % women in both groups. A total of 158 (7 %) AA and 9 (3 %) HA (P = 0.014) underwent the procedures for CRC screening. When compared to HAs, AAs had higher prevalence of any polyp (35 vs. 18 %, OR = 2.53; 95 % CI 1.82-3.52). Overall, AA had higher prevalence of colorectal neoplasia (adenoma and cancer) when compared to HAs (16 vs. 10 %; OR = 1.68; 95 % CI 1.10-2.56). CONCLUSION: We observed a higher frequency of colorectal neoplasia among 40-49-year-old AAs as compared to HAs suggesting an increased susceptibility to CRC risk in this population.

Low-Cost, High-Pressure-Synthesized Oxygen-Entrapping Materials to Improve Treatment of Solid Tumors.

Tumor hypoxia drives resistance to many cancer therapies, including radiotherapy and chemotherapy. Methods that increase tumor oxygen pressures, such as hyperbaric oxygen therapy and microbubble infusion, are utilized to improve the responses to current standard-of-care therapies. However, key obstacles remain, in particular delivery of oxygen at the appropriate dose and with optimal pharmacokinetics. Toward overcoming these hurdles, gas-entrapping materials (GeMs) that are capable of tunable oxygen release are formulated. It is shown that injection or implantation of these materials into tumors can mitigate tumor hypoxia by delivering oxygen locally and that these GeMs enhance responsiveness to radiation and chemotherapy in multiple tumor types. This paper also demonstrates, by comparing an oxygen (O2 )-GeM to a sham GeM, that the former generates an antitumorigenic and immunogenic tumor microenvironment in malignant peripheral nerve sheath tumors. Collectively the results indicate that the use of O2 -GeMs is promising as an adjunctive strategy for the treatment of solid tumors.

Early anti-oxidative and anti-proliferative curcumin effects on neuroglioma cells suggest therapeutic targets.

Curcumin (diferuloyl), from the Indian spice turmeric, reduces oxidative damage and induces apoptosis. Utilizing DNA microarrays, we have demonstrated that a low (5 microM) dose of curcumin added to a mixture of astrocytes and oligodendrocytes (C6 rat glioma cells) in culture for 24 and 48 h significantly modulates gene expression in four primary pathways: oxidative stress, cell cycle control, and DNA transcription and metabolism. Contribution of the pentose phosphate pathway to the pool of NADH upregulates glutathione and activates aldehyde oxidase. We have identified also several new genes, up- or downregulated by curcumin, namely, aldo-keto reductase, glucose-6-phosphate dehydrogenase, and aldehyde oxidase that protect against oxidative stress. The identification of several new cell cycle control genes, including the apoptosis-related protein (pirin) and insulin-like growth factor (IGF), and of the neurofilament M protein involved in neurogenesis suggests that curcumin may have applicability in the treatment of a spectrum of neurodegenerative diseases.

Nickel-catalyzed, ligand-free, diastereoselective synthesis of 3-methyleneindan-1-ols.

Nickel-catalyzed, highly diastereoselective annulations between activated allenes and 2-acetylarylboronic acid or 2-formylarylboronic acids are reported. No ligand for nickel is required, and the reactions proceed efficiently at room temperature to give a broad range of substituted 3-methyleneindan-1-ols. Preliminary results of an enantioselective variant are also described.

Synthesis of multisubstituted pyrroles by nickel-catalyzed arylative cyclizations of N-tosyl alkynamides.

The synthesis of multisubstituted pyrroles by the nickel-catalyzed reaction of N-tosyl alkynamides with arylboronic acids is reported. These reactions are triggered by alkyne arylnickelation, followed by cyclization of the resulting alkenylnickel species onto the amide. The reversible E/Z isomerization of the alkenylnickel species is critical for cyclization. This method was applied to the synthesis of pyrroles that are precursors to BODIPY derivatives and a biologically active compound.

Neuregulin3 alters cell fate in the epidermis and mammary gland.

BACKGROUND: The Neuregulin family of ligands and their receptors, the Erbb tyrosine kinases, have important roles in epidermal and mammary gland development as well as during carcinogenesis. Previously, we demonstrated that Neuregulin3 (Nrg3) is a specification signal for mammary placode formation in mice. Nrg3 is a growth factor, which binds and activates Erbb4, a receptor tyrosine kinase that regulates cell proliferation and differentiation. To understand the role of Neuregulin3 in epidermal morphogenesis, we have developed a transgenic mouse model that expresses Nrg3 throughout the basal layer (progenitor/stem cell compartment) of mouse epidermis and the outer root sheath of developing hair follicles. RESULTS: Transgenic females formed supernumerary nipples and mammary glands along and adjacent to the mammary line providing strong evidence that Nrg3 has a role in the initiation of mammary placodes along the body axis. In addition, alterations in morphogenesis and differentiation of other epidermal appendages were observed, including the hair follicles. The transgenic epidermis is hyperplastic with excessive sebaceous differentiation and shows striking similarities to mouse models in which c-Myc is activated in the basal layer including decreased expression levels of the adhesion receptors, alpha6-integrin and beta1-integrin. CONCLUSION: These results indicate that the epidermis is sensitive to Nrg3 signaling, and that this growth factor can regulate cell fate of pluripotent epidermal cell populations including that of the mammary gland. Nrg3 appears to act, in part, by inducing c-Myc, altering the proliferation and adhesion properties of the basal epidermis, and may promote exit from the stem cell compartment. The results we describe provide significant insight into how growth factors, such as Nrg3, regulate epidermal homeostasis by influencing the balance between stem cell renewal, lineage selection and differentiation.

Seasonal variations in outcomes after kidney transplantation: UNOS review of 336,330 transplants.

INTRODUCTION: The "July effect" is a widely discussed phenomenon of worse patient outcomes at teaching hospitals in July due to inexperienced house staff. METHODS: We conducted a retrospective review of Organ Procurement and Transplantation Network data from Oct 1, 1987 to June 30, 2011, including longitudinal censored data of 360,330 transplantations. Demographic and comorbid variables for donors and recipients were collected. Primary outcomes were graft loss, patient death, and delayed graft function. Secondary outcomes were surgical complications, length of stay, and graft rejection. We compared survival indicators (1-month, 1-, 3-, and 5-year survival and median survival times) for both grafts and patients. We also analyzed death-censored graft survival. RESULTS: There were fewer July donors with diabetes (p = 0.003), hypertension (p = 0.000), and extended criteria (p<0.0001). Graft survival (p = 0.000), death-censored graft survival (p = 0.001), and patient survival (p = 0.002) were statistically higher in July. After adjusting the Cox model for extended criteria donors, there was no difference in outcomes (p>0.05 for graft, death-censored graft survival, and patient survival). CONCLUSION: We conclude that there is no July effect. Initially identified, superior outcomes in July may be attributed to more conservative allografts selection in the beginning of the academic year.

Embryonic mammary anlagen analysis using immunolabelling of whole mounts.

The mouse mammary gland is a unique organ since although the mammary gland primordium forms during embryogenesis, the majority of development occurs postnatally upon hormonal stimulation at puberty and full functionality (i.e. lactation) is not achieved until after parturition. Since both the epidermis and mammary glands share the same developmental origin, many mouse models with epidermal phenotypes often also exhibit abnormal mammary gland development. However, since the most widely used methods to analyse mammary glands are laborious and time-consuming, many mouse models exist that have not been analysed for mammary phenotypes. We have developed a simplified method that allows rapid analysis of embryonic mammary anlagen using immunolabelling of whole mounts that should facilitate more comprehensive studies of mouse mammary glands.

Dynamic expression of Erbb pathway members during early mammary gland morphogenesis.

Similar to other epithelial appendages, mammary anlagen progress from stratified epithelium through placode and bud stages. Embryonic mammary morphogenesis is elicited by a combination of local cell migration, adhesion changes and proliferation, and these same developmental processes impact breast cancer etiology. The Erbb signaling network plays important roles in postnatal mammary gland morphogenesis and carcinogenesis. Neuregulin3 (Nrg3), an Erbb family ligand, has recently been shown to be involved in the specification of mammary glands in mice. To further examine the possible involvement of other Erbb family members and their ligands in early mammary morphogenesis, we have characterized their expression patterns during this process. We used whole mount in situ hybridization to analyze the expression patterns of these genes at stages prior to and during mammary placode formation. Immunohistochemistry was used to examine expression patterns at later bud stages. The Neuregulin ligands, Nrg1, Nrg2, Nrg3, Nrg4 and the receptors, Erbb1, Erbb2, Erbb3, Erbb4, were expressed either at stages prior to morphological appearance of the mammary placode or from the time that the placode is first morphologically distinct through to later bud stages. The expression patterns presented here suggest that multiple members of this signaling network are potential mediators of early mammary morphogenesis.

Identification of the scaramanga gene implicates Neuregulin3 in mammary gland specification.

The mouse scaramanga (ska) mutation impairs mammary gland development such that both abrogation and stimulation of gland formation occurs. We used positional cloning to narrow the interval containing scaramanga (ska) to a 75.6-kb interval containing the distal part of the Neuregulin3 (Nrg3) gene. Within this region the only sequence difference between ska and wild-type mice is in a microsatellite repeat within intron 7. This alteration correlates with variations in Nrg3 expression profiles both at the whole embryo level and locally in the presumptive mammary region in ska mice. Localized expression of Nrg3 and its receptor, Erbb4, in the presumptive mammary region around the future bud site prior to morphological appearance of buds and the expression of bud epithelial markers further support an inductive role. Finally, Neuregulin3 (Nrg3)-soaked beads can induce expression of the early bud marker Lef1 in mouse embryo explant cultures, and epithelial bud formation can be observed histologically, suggesting that initiation of mammary bud development occurs. Taken together, these results indicate that a Neuregulin signaling pathway is involved in specification of mammary gland morphogenesis and support the long-held view that mesenchymal signal(s) are responsible for mammary gland inductive/initiating events.