Sex-related differences in death control of somatic cells

In 2001, The United States Institute of Medicine (IOM) Committee on Understanding the Biology of Sex and Gender Differences concluded that ‘Sex…should be considered when designing and analysing studies in all areas and at all levels of biomedical and health-related research…’ and stated an apparent paradox i.e.: ‘every cell has a sex’ 1. Sex is defined as ‘the classification of living things, generally as male or female according to their reproductive organs and functions assigned by chromosomal complement’ whereas gender is defined as ‘a person's self representation as male or female, or how that person is responded to by social institutions based on the individual's gender presentation. Gender is rooted in biology and shaped by environment and experience’ 1. It is unchallenged that there are health differences between males and females and that social and cultural factors could contribute to the observed differences. Anyway, the sex-dependent differences also have a biological base which sometimes has not been deeply investigated. Scientists studying health differences between male and female aim to both considering social/cultural environment and investigating biological/molecular mechanisms different between sexes. Some experimental studies have elucidated important differences in cell death control 2. A sex disparity, in fact, has been shown both in the propensity to apoptosis and in the activation of the autophagic pathway. In the context of cell fate control, hormones represent important regulators of both apoptosis and autophagy. In the cardiovascular system, for example, oestrogens inhibit cardiomyocyte apoptosis by decreasing reactive oxygen species production and increasing intracellular antioxidants 3. Oestrogens may also indirectly control autophagy as they up-regulate urocortin 4, a neuropeptide hormone able to inhibiting autophagy in cardiomyocytes. Conversely, increasing evidence suggests possible adverse effects of androgens on the vasculature showing that androgens, as opposed to oestrogens, may worsen vascular dysfunction in men, thus contributing to sex-based differences in cardiovascular diseases 5. However, it is currently emerging that some cell death programs are differentially controlled by sex-related hormone-independent cellular genetics. Differences in cell death sensitivity in male and female may then occur in the absence of an hormonal context. This is not an immediately obvious finding; Penaloza C et al., 6 have shown that the apoptosis amount differs between the sexes in isolated embryonic cells exposed to similar conditions and this happens at embryonal stages where there are no hormonal influences. Previous studies had reported a sexual dimorphism in embryonic neuronal signal transduction pathways and consequently differences in cell survival 7. Death pathways in XX and XY cells have been poorly investigated as most studies have been performed on established cells lines often irrespective of their male or female origin. Recently, using freshly isolated cells from male and female individuals gave important information on sex disparity in cell fate control. Such sex specificity has been in part clarified thanks to cell culture models where sex steroids can be removed from the media. Even sex-related differences in caspase activation have been found to be independent on hormone exposure. More in detail, cell death occurring in cortical neurons after ischaemia proceeds predominantly via an apoptosis-inducing factor-dependent pathway (a caspase-independent pathway) in male neurons while proceeds via a cytochrome C-dependent pathway (a process mediated by caspase activation) in female neurons 8. In this context, a sex-specific microRNA expression after ischaemia has been described in in vivo studies. In particular, it has been demonstrated that microRNA-23a, by binding the mRNA of the caspase inhibitor named XIAP, induces its translational repression in females, leading to enhanced caspase signalling in the ischaemic female brain. This effect has been shown to be independent of circulating oestrogen levels 9. Sex differences in ischaemic brain injury and cerebrovascular regulation have been observed in clinical and experimental studies and an important determinant of such differences is also represented by the integrity of endothelial cells. In fact, endothelial function is improved in women compared with men, contributing to female cellular higher resistance after ischaemic brain injury. Gupta NC et al. 10 showed that female cerebrovascular endothelial cells express lower level of soluble epoxide hydrolase and consequently have higher levels of vasoprotective epoxyeicosatrienoic acids as compared with male endothelial cells. This study therefore presents a novel additional mechanism underlying differences between male and female cells in apoptotic response after oxygen-glucose deprivation, contributing to explain higher resistance observed in females as compared with males. This study remarks again that differences between male and female cells do not necessarily depend on the hormonal context but may be inherent the cells. We believe that this apparently paradoxical concept has not been sufficiently highlighted in the scientific literature. The present ‘Letter to the Editor’ therefore aims at underlining such an important issue which deserves more attention and discussion in the researchers' community. A practical consequence of sex-dependent discrepancies in cell death control is that cellular response to any stimulus or treatment, in any physiological or pathological context, may well depend on the sex of the cell line used; journals guidelines should therefore require authors to state in any case the sex of the cell lines used in any in vitro study. In addition, at least to some extent, sex-matched or sex-unmatched cell controls may be necessary in many experimental settings. In conclusion, sex-related differences in cell death mechanism may have strong implications for experimental studies and sexual dimorphism dependent on chromosomal rather than hormonal differences have important implications for planning preclinical studies and clinical interventions

Transfected poly(I:C) activates different dsRNA receptors leading to apoptosis or immunoadjuvant response in androgen-independent prostate cancer cells

Background: Castration-resistant prostate cancer (CRPC) is refractory to chemo-radiotherapy. Results: Transfection of the synthetic analog of dsRNA poly(I:C) simultaneously stimulates apoptosis and IFN- expression through different pathways in androgen-independent prostate cancer (PCa) cells. Conclusion: Dual parallel pathways triggered by distinct receptors activate direct and immunologically mediated antitumor effects in advanced PCa. Significance: The proapoptotic/immunoadjuvant poly(I:C)-Lipofectamine complex may offer new therapeutic insights into CRPC

Cancer microenvironment and endoplasmic reticulum stress response

Different stressful conditions such as hypoxia, nutrient deprivation, pH changes, or reduced vascularization, potentially able to act as growth-limiting factors for tumor cells, activate the unfolded protein response (UPR). UPR is therefore involved in tumor growth and adaptation to severe environments and is generally cytoprotective in cancer. The present review describes the molecular mechanisms underlying UPR and able to promote survival and proliferation in cancer. The critical role of UPR activation in tumor growth promotion is discussed in detail for a few paradigmatic tumors such as prostate cancer and melanoma

Lipid storage and autophagy in melanoma cancer cells

Cancer stem cells (CSC) represent a key cellular subpopulation controlling biological features such as cancer progression in all cancer types. By using melanospheres established from human melanoma patients, we compared less differentiated melanosphere-derived CSC to differentiating melanosphere-derived cells. Increased lipid uptake was found in melanosphere-derived CSC vs. differentiating melanosphere-derived cells, paralleled by strong expression of lipogenic factors Sterol Regulatory Element-Binding Protein-1 (SREBP-1) and Peroxisome Proliferator-Activated Receptor-γ (PPAR-γ). An inverse relation between lipid-storing phenotype and autophagy was also found, since microtubule-associated protein 1A/1B-Light Chain 3 (LC3) lipidation is reduced in melanosphere-derived CSC. To investigate upstream autophagy regulators, Phospho-AMP activated Protein Kinase (P-AMPK) and Phospho-mammalian Target of Rapamycin (P-mTOR) were analyzed; lower P-AMPK and higher P-mTOR expression in melanosphere-derived CSC were found, thus explaining, at least in part, their lower autophagic activity. In addition, co-localization of LC3-stained autophagosome spots and perilipin-stained lipid droplets was demonstrated mainly in differentiating melanosphere-derived cells, further supporting the role of autophagy in lipid droplets clearance. The present manuscript demonstrates an inverse relationship between lipid-storing phenotype and melanoma stem cells differentiation, providing novel indications involving autophagy in melanoma stem cells biology

The role of autophagy in liver epithelial cells and its Impact on systemic homeostasis

Autophagy plays a role in several physiological and pathological processes as it controls the turnover rate of cellular components and influences cellular homeostasis. The liver plays a central role in controlling organisms’ metabolism, regulating glucose storage, plasma proteins and bile synthesis and the removal of toxic substances. Liver functions are particularly sensitive to autophagy modulation. In this review we summarize studies investigating how autophagy influences the hepatic metabolism, focusing on fat accumulation and lipids turnover. We also describe how autophagy affects bile production and the scavenger function within the complex homeostasis of the liver. We underline the role of hepatic autophagy in counteracting the metabolic syndrome and the associated cardiovascular risk. Finally, we highlight recent reports demonstrating how the autophagy occurring within the liver may affect skeletal muscle homeostasis as well as different extrahepatic solid tumors, such as melanoma

TLR3 engagement induces IRF-3-dependent apoptosis in androgen-sensitive prostate cancer cells and inhibits tumour growth in vivo

Toll-like receptors (TLRs) are a family of highly conserved transmembrane proteins expressed in epithelial and immune cells that recognize pathogen associated molecular patterns. Besides their role in immune response against infections, numerous studies have shown an important role of different TLRs in cancer, indicating these receptors as potential targets for cancer therapy. We previously demonstrated that the activation of TLR3 by the synthetic double-stranded RNA analogue poly I:C induces apoptosis of androgen-sensitive prostate cancer (PCa) LNCaP cells and, much less efficiently, of the more aggressive PC3 cell line. Therefore, in this study we selected LNCaP cells to investigate the mechanism of TLR3-mediated apoptosis and the in vivo efficacy of poly I:C-based therapy. We show that interferon regulatory factor-3 (IRF-3) signalling plays an essential role in TLR3-mediated apoptosis in LNCaP cells through the activation of the intrinsic and extrinsic apoptotic pathways. Interestingly, hardly any apoptosis was induced by poly I:C in normal prostate epithelial cells RWPE-1. We also demonstrate for the first time the direct anticancer effect of poly I:C as a single therapeutic agent in a well-established human androgen-sensitive PCa xenograft model, by showing that tumour growth is highly impaired in poly I:C-treated immunodeficient mice. Immunohistochemical analysis of PCa xenografts highlights the antitumour role of poly I:C in vivo both on cancer cells and, indirectly, on endothelial cells. Notably, we show the presence of TLR3 and IRF-3 in both human normal and PCa clinical samples, potentially envisaging poly I:C-based therapy for PCa

The adherent/invasive escherichia coli (AIEC) strain LF82 invades and persists in human prostate cell lineRWPE-1 activating a strong inflammatory response

Adherent/invasive Escherichia coli (AIEC) strains have recently been receiving increased attention because they are more prevalent and persistent in the intestine of Crohn's disease (CD) patients than in healthy subjects. Since AIEC strains show a high percentage of similarity to extraintestinal pathogenic E. coli (ExPEC), neonatal meningitis-associated E. coli (NMEC), and uropathogenic E. coli (UPEC) strains, here we compared AIEC strain LF82 with a UPEC isolate (strain EC73) to assess whether LF82 would be able to infect prostate cells as an extraintestinal target. The virulence phenotypes of both strains were determined by using the RWPE-1 prostate cell line. The results obtained indicated that LF82 and EC73 are able to adhere to, invade, and survive within prostate epithelial cells. Invasion was confirmed by immunofluorescence and electron microscopy. Moreover, cytochalasin D and colchicine strongly inhibited bacterial uptake of both strains, indicating the involvement of actin microfilaments and microtubules in host cell invasion. Moreover, both strains belong to phylogenetic group B2 and are strong biofilm producers. In silico analysis reveals that LF82 shares with UPEC strains several virulence factors: namely, type 1 pili, the group II capsule, the vacuolating autotransporter toxin, four iron uptake systems, and the pathogenic island (PAI). Furthermore, compared to EC73, LF82 induces in RWPE-1 cells a marked increase of phosphorylation of mitogen-activated protein kinases (MAPKs) and of NF-κB already by 5 min postinfection, thus inducing a strong inflammatory response. Our in vitro data support the hypothesis that AIEC strains might play a role in prostatitis, and, by exploiting host-cell signaling pathways controlling the innate immune response, likely facilitate bacterial multiplication and dissemination within the male genitourinary trac

Interference coloration as an anti-predator defence

Interference coloration, in which the perceived colour varies predictably with the angle of illumination or observation, is extremely widespread across animal groups. However, despite considerable advances in our understanding of the mechanistic basis of interference coloration in animals, we still have a poor understanding of its function. Here, I show, using avian predators hunting dynamic virtual prey, that the presence of interference coloration can significantly reduce a predator's attack success. Predators required more pecks to successfully catch interference-coloured prey compared with otherwise identical prey items that lacked interference coloration, and attacks against prey with interference colours were less accurate, suggesting that changes in colour or brightness caused by prey movement hindered a predator's ability to pinpoint their exact location. The pronounced antipredator benefits of interference coloration may explain why it has evolved independently so many times. © 2015 The Author(s) Published by the Royal Society. All rights reserved

Activation of Jun N-terminal Kinase/Stress-activated Protein Kinase Pathway by Tumor Necrosis Factor α Leads to Intercellular Adhesion Molecule-1 Expression

Tumor necrosis factor alpha (TNF-alpha) is a cytokine implicated in the pathogenesis of numerous chronic and acute inflammatory conditions. We have previously shown that mouse Sertoli cells respond to TNF-alpha by increasing interleukin-6 production and intercellular adhesion molecule-1 (ICAM-1) expression (1). In this cell type TNF-alpha activates the mitogen-activated protein kinase (MAPK) pathways p42/p44 MAPK, JNK/SAPK, and p38, the last of which is responsible for interleukin-6 production (1). To determine which MAPK signaling pathway is required for TNF-alpha induction of ICAM-1 expression, we have utilized the protein kinase inhibitor dimethylaminopurine, demonstrating that treatment of Sertoli cells with such compound significantly reduced ICAM-1 expression and JNK/SAPK activation. Moreover, dimethylaminopurine treatment increased the expression of MAPK phosphatase-2, providing a possible mechanism of action of this compound. By using agonist antibodies to p55 and to p75 TNF-alpha receptors and both human and mouse TNF-alpha, we demonstrate that both TNF receptors are expressed and that only the p55 receptor is involved in ICAM-1 expression. The p55 receptor activates all of the three pathways, whereas p75 failed to activate any of the MAPKs. Altogether our results demonstrate that TNF-alpha up-regulates ICAM-1 expression through the activation of the JNK/SAPK transduction pathway mediated by the p55 receptor