The impact of elevated temperature and CO2 on growth, physiological and immune responses of Polypedates cruciger (common hourglass tree frog).

BACKGROUND: Amphibians are one of the most susceptible groups to climate change as their development occurs in aquatic environments or in microhabitats with high humidity. Accordingly, our primary objective was to investigate the chronic physiological responses seen in early larval to adult stages of Polypedates cruciger (Common hourglass tree frog) to future climate change based on continuous exposure to elevated temperature and elevated CO2 -induced low water pH. Free-swimming and free-feeding tadpoles were observed until metamorphosis under four experimental treatments; two elevated temperatures, one elevated CO2 (reduced pH) and a control maintained at ambient temperature (29 °C ± 1 °C) and CO2 (pH = 7). Elevated temperature treatments were maintained at 32 °C ± 0.5 °C and 34 °C ± 0.5 °C to represent respectively, the future climate scenarios RCP2.6 (Representative Concentration Pathway 2.6, the 'base-case' scenario) and RCP8.5 ('business-as-usual' scenario) according to the 5th Assessment Report of the IPCC. Elevated CO2 treatment was maintained within the pH range of 5.5-5.6 representing the range expected between RCP8.5 and RCP2.6. RESULTS: Compared to the control, elevated CO2 accelerated phenological progression of tadpoles through Gosner stages, thus resulting in lower body size at metamorphosis. Both elevated temperatures significantly delayed the development and reduced the growth of tadpoles. 100% mortality was observed in 34 °C treatment before metamorphosis (before Gosner stage 36) while all the tadpoles died after metamorphosis (at Gosner stage 46) in 32 °C treatment. Elevated CO2 increased tadpole activity, in terms of their swimming speed, while both of the elevated temperatures reduced it compared to the control. Catalase activity increased at elevated CO2. Ammonia excretion by tadpoles was decreased by elevated CO2, but increased under temperature elevation. Both Elevated CO2 and temperature treatments reduced the white blood cell count and its percentage of thrombocytes. Percentages of lymphocytes, monocytes and neutrophils were increased at 32 °C, while lymphocyte percentage and lysozyme activity were increased at elevated CO2. Several deformities were observed in tadpoles at elevated temperature and CO2. CONCLUSIONS: Elevated temperatures and reduced pH due to elevated CO2, being major features of climate change, increase the vulnerability of amphibians, who are already one of the most threatened vertebrate groups. Based on our observations on the model amphibian species P. cruciger, increased vulnerability to climate change occurs by reducing their growth, body size and motility while also reducing their immunity and inducing physical deformities. These impacts are highly-likely to reduce the foraging, competitive and reproductive capabilities in their natural habitats. We conclude further that even the 'best-case' scenario of future climate change can impose significant physiological impacts that could threaten amphibian populations on broader spatial and temporal scales.

Somatic loss of estrogen receptor beta and p53 synergize to induce breast tumorigenesis.

BACKGROUND: Upregulation of estrogen receptor beta (ERß) in breast cancer cells is associated with epithelial maintenance, decreased proliferation and invasion, and a reduction in the expression of the receptor has been observed in invasive breast tumors. However, proof of an association between loss of ERß and breast carcinogenesis is still missing. METHODS: To study the role of ERß in breast oncogenesis, we generated mouse conditional mutants with specific inactivation of ERß and p53 in the mammary gland epithelium. For epithelium-specific knockout of ERß and p53, ERß F/F and p53 F/F mice were crossed to transgenic mice that express the Cre recombinase under the control of the human keratin 14 promoter. RESULTS: Somatic loss of ERß significantly accelerated formation of p53-deficient mammary tumors. Loss of the receptor also resulted in the development of less differentiated carcinomas with stronger spindle cell morphology and decreased expression of luminal epithelial markers. CONCLUSIONS: Our results show that synergism between ERß and p53 inactivation functions to determine important aspects of breast oncogenesis and cancer progression.

Estrogen signaling and unfolded protein response in breast cancer.

Activation of the unfolded protein response (UPR) confers resistance to anti-estrogens and chemotherapeutics in estrogen receptor α (ERα)-positive and triple-negative breast cancers. Among the regulators of the UPR in breast cancer is estrogen signaling. Estrogen regulates major components of the UPR and ER expression is associated with the sensitivity of tumor cells to UPR-regulated apoptosis. Recent studies have confirmed the crosstalk between the ERs and UPR and suggest novel therapeutic strategies that combine targeting of both signaling pathways. These remedies may be more effective in repressing oncogenic adaptive mechanisms and benefit patients with resistant disease.

ERß decreases the invasiveness of triple-negative breast cancer cells by regulating mutant p53 oncogenic function.

Most (80%) of the triple-negative breast cancers (TNBCs) express mutant p53 proteins that acquire oncogenic activities including promoting metastasis. We previously showed that wild-type ERß (ERß1) impedes epithelial to mesenchymal transition (EMT) and decreases the invasiveness of TNBC cells. In the present study we searched for signaling pathways that ERß1 uses to inhibit EMT and invasion in TNBC cells. We show that ERß1 binds to and opposes the transcriptional activity of mutant p53 at the promoters of genes that regulate metastasis. p63 that transcriptionally cooperates with mutant p53 also binds to ERß1. Downregulation of p63 represses the epithelial phenotype of ERß1-expressing cells and alters the expression of mutant p53 target genes. These results describe a novel mechanism through which ERß1 can disturb oncogenic signals to inhibit aggressiveness in TNBCs.

ERß regulates NSCLC phenotypes by controlling oncogenic RAS signaling.

UNLABELLED: Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related deaths worldwide. In addition to the aberrant growth factor signaling, dysregulation of other pathways, such as those mediated by estrogens and their receptors, has been linked to NSCLC initiation and progression. Although the expression of wild-type estrogen receptor ß (ERß1) has been associated with prolonged disease-free survival in patients with NSCLC, the molecular mechanism that accounts for this correlation is unknown. Here, upregulation of ERß1 reduced proliferation and enhanced apoptosis in the context of mutant RAS. ERß1 was found to induce apoptosis by stimulating the intrinsic apoptotic pathway that involves BIM, a Bcl-2 proapoptotic family member that is regulated by the extracellular signal-regulated kinase (ERK). Downregulation of EGFR and inactivation of RAS and the downstream components ERK1/2 were found to be involved in the ERß1-induced apoptosis. Manipulation of EGFR and RAS expression and activity in ERß1-expressing cells revealed the central role of oncogenic RAS inhibition in the ERß1-mediated proapoptotic phenotype and EGFR regulation. These results demonstrate that ERß1 decreases the survival of NSCLC cells by regulating oncogenic RAS signaling. IMPLICATIONS: The ability of ERß1 to regulate the oncogenic functions of RAS suggests its importance in the biology of NSCLC and its clinical management. Mol Cancer Res; 12(6); 843-54. ©2014 AACR.

ERbeta1 represses basal breast cancer epithelial to mesenchymal transition by destabilizing EGFR.

INTRODUCTION: Epithelial to mesenchymal transition (EMT) is associated with the basal-like breast cancer phenotypes. 60% of basal-like cancers have been shown to express wild-type estrogen receptor beta (ERbeta1). However, it is still unclear whether the ERbeta expression is related to EMT, invasion and metastasis in breast cancer. In the present study, we examined whether ERbeta1 through regulating EMT can influence invasion and metastasis in basal-like cancers. METHODS: Basal-like breast cancer cells (MDA-MB-231 and Hs578T) in which ERbeta1 was either overexpressed or downregulated were analyzed for their ability to migrate and invade (wound-healing assay, matrigel-coated Transwell assay) as well as for the expression of EMT markers and components of the EGFR pathway (immunoblotting, RT-PCR). Coimmunoprecipitation and ubiquitylation assays were employed to examine whether ERbeta1 alters EGFR protein degradation and the interaction between EGFR and the ubiquitin ligase c-Cbl. The metastatic potential of the ERbeta1-expressing MDA-MB-231 cells was evaluated in vivo in a zebrafish xenotransplantation model and the correlation between ERbeta1 and E-cadherin expression was examined in 208 clinical breast cancer specimens by immunohistochemistry. RESULTS: Here we show that ERbeta1 inhibits EMT and invasion in basal-like breast cancer cells when they grow either in vitro or in vivo in zebrafish. The inhibition of EMT correlates with an ERbeta1-mediated upregulation of miR-200a/b/429 and the subsequent repression of ZEB1 and SIP1, which results in increased expression of E-cadherin. The positive correlation of ERbeta1 and E-cadherin expression was additionally observed in breast tumor samples. Downregulation of the basal marker EGFR through stabilization of the ubiquitin ligase c-Cbl complexes and subsequent ubiquitylation and degradation of the activated receptor is involved in the ERbeta1-mediated repression of EMT and induction of EGFR signaling abolished the ability of ERbeta1 to sustain the epithelial phenotype. CONCLUSIONS: Taken together, the results of our study strengthen the association of ERbeta1 with the regulation of EMT and propose the receptor as a potential crucial marker in predicting metastasis in breast cancer.