Protein kinase D1 is essential for Ras-induced senescence and tumor suppression by regulating senescence-associated inflammation

The senescence-associated secretory phenotype and its physiological and pathological implications

Cellular senescence is a state of terminal growth arrest associated with the upregulation of different cell cycle inhibitors, mainly p16 and p21, structural and metabolic alterations, chronic DNA damage responses, and a hypersecretory state known as the senescence-associated secretory phenotype (SASP). The SASP is the major mediator of the paracrine effects of senescent cells in their tissue microenvironment and of various local and systemic biological functions. In this Review, we discuss the composition, dynamics and heterogeneity of the SASP as well as the mechanisms underlying its induction and regulation. We describe the various biological properties of the SASP, its beneficial and detrimental effects in different physiological and pathological settings, and its impact on overall health span. Finally, we discuss the use of the SASP as a biomarker and of SASP inhibitors as senomorphic interventions to treat cancer and other age-related conditions.

Macrophage-induced reactive oxygen species in the initiation of pancreatic cancer: a mini-review

Pancreatic inflammation is a risk factor for the development of pancreatic cancer. Increased presence of inflammatory macrophages can be found in response to a KRAS mutation in acinar cells or in response to experimentally-induced pancreatitis. Inflammatory macrophages induce pancreatic acinar cells to undergo dedifferentiation to a duct-like progenitor stage, a process called acinar-to-ductal metaplasia (ADM). Occurrence of ADM lesions are believed to be the initiating event in tumorigenesis. Here we will discuss how macrophage-induced oxidative stress contributes to ADM and how ADM cells shape the fibrotic stroma needed for further progression.

Protein kinase D1 - A targetable mediator of pancreatic cancer development

Members of the Protein kinase D (PKD) kinase family each play important cell-specific roles in the regulation of normal pancreas functions. In pancreatic diseases PKD1 is the most widely characterized isoform with roles in pancreatitis and in induction of pancreatic cancer and its progression. PKD1 expression and activation increases in pancreatic acinar cells through macrophage secreted factors, Kirsten rat sarcoma viral oncogene homolog (KRAS) signaling, and reactive oxygen species (ROS), driving the formation of precancerous lesions. In precancerous lesions PKD1 regulates cell survival, growth, senescence, and generation of doublecortin like kinase 1 (DCLK1)-positive cancer stem cells (CSCs). Within tumors, regulation by PKD1 includes chemoresistance, apoptosis, proliferation, CSC features, and the Warburg effect. Thus, PKD1 plays a critical role throughout pancreatic disease initiation and progression.

Depression and Hand-Grip: Unraveling the Association

This review article explores the association between hand-grip strength and depression. A total of 14 studies were carefully considered to provide a comprehensive analysis of the topic. The studies reveal a consistent association between low hand-grip strength and depressive symptoms, independent of age, gender, and chronic disease status. The evidence suggests that hand-grip strength assessment could be a useful tool for identifying individuals at risk of depression, particularly older adults and those with chronic diseases. Incorporating physical activity and strength training into treatment plans can contribute to better mental health outcomes. Hand-grip strength assessment can also be used as a monitoring tool to track changes in physical and mental health over time in individuals with depression. Healthcare professionals should consider the relationship between hand-grip strength and depression when evaluating patients and developing treatment plans. The findings from this comprehensive clinical review have important clinical implications and highlight the importance of considering physical health factors in the context of mental health.

The role of cellular senescence and SASP in tumour microenvironment

Cellular senescence refers to a state of irreversible cell cycle arrest that can be induced by various cellular stresses and is known to play a pivotal role in tumour suppression. While senescence-associated growth arrest can inhibit the proliferation of cancer-prone cells, the altered secretory profile of senescent cells, termed the senescence-associated secretory phenotype, can contribute to the microenvironment that promotes tumour development. Although the senescence-associated secretory phenotype and its effects on tumorigenesis are both highly context dependent, mechanisms underlying such diversity are becoming better understood, thereby allowing the creation of new strategies to effectively target the senescence-associated secretory phenotype and senescent cells for cancer therapy. In this review, we discuss the current knowledge on cellular senescence and the senescence-associated secretory phenotype to develop a structural understanding of their roles in the tumour microenvironment and provide perspectives for future research, including the possibility of senotherapy for the treatment of cancer.

A genetic correlation and bivariate genome-wide association study of grip strength and depression

Grip strength is an important biomarker reflecting muscle strength, and depression is a psychiatric disorder all over the world. Several studies found a significant inverse association between grip strength and depression, and there is also evidence for common physiological mechanisms between them. We used twin data from Qingdao, China to calculate genetic correlations, and we performed a bivariate GWAS to explore potential SNPs, genes, and pathways in common between grip strength and depression. 139 pairs of Dizygotic twins were used for bivariate GWAS. VEAGSE2 and PASCAL software were used for gene-based analysis and pathway enrichment analysis, respectively. And the resulting SNPs were subjected to eQTL analysis and pleiotropy analysis. The genetic correlation coefficient between grip strength and depression was -0.41 (-0.96, -0.15). In SNP-based analysis, 7 SNPs exceeded the genome-wide significance level (P<5×10-8) and a total of 336 SNPs reached the level of suggestive significance (P<1×10-5). Gene-based analysis and pathway-based analysis identified genes and pathways related to muscle strength and the nervous system. The results of eQTL analysis were mainly enriched in tissues such as the brain, thyroid, and skeletal muscle. Pleiotropy analysis shows that 9 of the 15 top SNPs were associated with both grip strength and depression. In conclusion, this bivariate GWAS identified potentially common pleiotropic SNPs, genes, and pathways in grip strength and depression.

Photooxidation of A2E by Blue Light Regulates Heme Oxygenase 1 Expression via NF-κB and Lysine Methyltransferase 2A in ARPE-19 Cells

Background: N-retinylidene-N-retinylethanolamine (A2E) is a component of drusen that accumulates in retinal cells and induces oxidative stress through photooxidation, such as blue light (BL). We found that the heme oxygenase 1 (HMOX1) gene responds sensitively to photooxidation by the BL of A2E in retinal pigment epithelial (RPE) cells, and we sought to identify the transcription factors and coactivators involved in the upregulation of HMOX1 by A2E and BL. Methods: A2E-laden human RPE cells (ARPE-19) were exposed to BL (430 nm). RNA sequencing was performed to identify genes responsive to BL exposure. Chromatin immunoprecipitation and RT-qPCR were performed to determine the regulation of HMOX1 transcription. Clinical transcriptome data were used to evaluate HMOX1 expression in patients with age-related macular degeneration (AMD). Results: In ARPE-19 cells, the expression of HMOX1, one of the NF-κB target genes, was significantly increased by A2E and BL. The binding of RELA and RNA polymerase II to the promoter region of HMOX1 was significantly increased by A2E and BL. Lysine methyltransferase 2A (MLL1) plays an important role in H3K4me3 methylation, NF-κB recruitment, chromatin remodeling at the HMOX1 promoter, and, subsequently, HMOX1 expression. The retinal tissues of patients with late-stage AMD showed significantly increased expression of HMOX1 compared to normal retinal tissues. In addition, the expression levels of MLL1 and HMOX1 in retinal tissues were correlated. Conclusions: Taken together, our results suggest that BL induces HMOX1 expression by activating NF-κB and MLL1 in RPE cells.

Link between senescence and cell fate: Senescence-associated secretory phenotype (SASP) and its effects on stem cell fate transition

Senescence is a form of durable cell cycle arrest elicited in response to a wide range of stimuli. Senescent cells remain metabolically active and secrete a variety of factors collectively termed senescence-associated secretory phenotype (SASP). SASP is highly pleiotropic and can impact numerous biological processes in which it has both beneficial and deleterious roles. The underlying mechanisms by which SASP exerts its pleiotropic influence remain largely unknown. SASP serves as an environmental factor, which regulates stem cell differentiation and alters its routine. The latter can potentially be accomplished through dedifferentiation, transdifferentiation, or reprogramming. Behavioral changes that cells undergo when exposed to SASP are involved in several senescence-associated physiological and pathological phenomena. These findings provide clues for identifying possible interventions to reduce the deleterious effects without interfering in the beneficial outcomes. Here, we discuss the multifaced effects of SASP and the changes occurring in cellular states upon exposure to SASP factors.

Senolytics and senomorphics: Natural and synthetic therapeutics in the treatment of aging and chronic diseases

Cellular senescence is a heterogeneous process guided by genetic, epigenetic and environmental factors, characterizing many types of somatic cells. It has been suggested as an aging hallmark that is believed to contribute to aging and chronic diseases. Senescent cells (SC) exhibit a specific senescence-associated secretory phenotype (SASP), mainly characterized by the production of proinflammatory and matrix-degrading molecules. When SC accumulate, a chronic, systemic, low-grade inflammation, known as inflammaging, is induced. In turn, this chronic immune system activation results in reduced SC clearance thus establishing a vicious circle that fuels inflammaging. SC accumulation represents a causal factor for various age-related pathologies. Targeting of several aging hallmarks has been suggested as a strategy to ameliorate healthspan and possibly lifespan. Consequently, SC and SASP are viewed as potential therapeutic targets either through the selective killing of SC or the selective SASP blockage, through natural or synthetic compounds. These compounds are members of a family of agents called senotherapeutics divided into senolytics and senomorphics. Few of them are already in clinical trials, possibly representing a future treatment of age-related pathologies including diseases such as atherosclerosis, osteoarthritis, osteoporosis, cancer, diabetes, neurodegenerative diseases such as Alzheimer's disease, cardiovascular diseases, hepatic steatosis, chronic obstructive pulmonary disease, idiopathic pulmonary fibrosis and age-related macular degeneration. In this review, we present the already identified senolytics and senomorphics focusing on their redox-sensitive properties. We describe the studies that revealed their effects on cellular senescence and enabled their nomination as novel anti-aging agents. We refer to the senolytics that are already in clinical trials and we present various adverse effects exhibited by senotherapeutics so far. Finally, we discuss aspects of the senotherapeutics that need improvement and we suggest the design of future senotherapeutics to target specific redox-regulated signaling pathways implicated either in the regulation of SASP or in the elimination of SC.

Flavonoids from Scutellaria baicalensis inhibit senescence-associated secretory phenotype production by interrupting IκBζ/C/EBPβ pathway: Inhibition of age-related inflammation

BACKGROUND

Prolonged exposure to the senescence-associated secretory phenotype (SASP) with age leads to chronic low-grade inflammation in neighboring cells and tissues, causing many chronic degenerative diseases.

PURPOSE

The effects on SASP production of the ethanol extract from Scutellaria radix and 17 isolated flavonoid constituents were examined in vitro and in vivo.

METHODS

Cellular senescence was induced by bleomycin. Expression of the SASP and cell signaling molecules was detected using ELISA, RT-qPCR, Western blotting, and immunofluorescence staining. To investigate the in vivo effects, 21-month-old aged rats were used.

RESULTS

The ethanol extract and 5 compounds including 1 (Oroxylin A; 5,7-dihydroxy-6-methoxyflavone), 5 (2',6',5,7-tetrahydroxy-8-methoxyflavone), 8 (2',5,7-trihydroxyflavone), 10 (2',5,7-trihydroxy-8-methoxyflavone) and 11 (2',5,7-trihydroxy-6-methoxyflavone) potently reduced IL-6 and IL-8 production and gene expression of the SASP, including IL-1α, IL-1β, IL-6, IL-8, GM-CSF, CXCL1, MCP-2, and MMP-3. This finding indicates the important role of the B-ring 2'‑hydroxyl group in flavonoid molecules. Furthermore, compounds 8 and 11, the strongest SASP inhibitors, decreased the expression of IκBζ and C/EBPβ protein without affecting either BrdU uptake or the expression of senescence markers, such as pRb and p21. Finally, the oral administration of compound 8 to aged rats at 2 and 4 mg/kg/day for 10 days significantly inhibited the gene expression of SASP and IκBζ in kidneys. This is the first report of the strong SASP inhibitory action of flavonoids from Scutellaria radix on in vitro and in vivo senescence models. The inhibitory action was shown to be mediated mainly by interfering with the IκBζ/C/EBPβ signaling pathway.

CONCLUSION

Targeting production of the SASP using flavonoids from Scutellaria radix or its extract might help reduce low-grade sterile inflammation and control age-related diseases.

S100A13 promotes senescence-associated secretory phenotype and cellular senescence via modulation of non-classical secretion of IL-1α

Senescent cells display the senescence-associated secretory phenotype (SASP) which plays important roles in cancer, aging, etc. Cell surface-bound IL-1α is a crucial SASP factor and acts as an upstream regulator to induce NF-κB activity and subsequent SASP genes transcription. IL-1α exports to cell surface via S100A13 protein-dependent non-classical secretory pathway. However, the status of this secretory pathway during cellular senescence and its role in cellular senescence remain unknown. Here, we show that S100A13 is up-regulated in various types of cellular senescence. S100A13 overexpression increases cell surface-associated IL-1α level, NF-κB activity and subsequent multiple SASP genes induction, whereas S100A13 knockdown has an opposite role. We also exhibit that Cu²⁺ level is elevated during cellular senescence. Lowering Cu²⁺ level decreases cell surface-bound IL-1α level, NF-κB activity and SASP production. Moreover, S100A13 overexpression promotes oncogene Ras-induced cell senescence (Ras OIS), Doxorubicin-induced cancer cell senescence (TIS) and replicative senescence, while impairment of non-classical secretory pathway of IL-1α delays cellular senescence. In addition, intervention of S100A13 affects multiple SASP and cellular senescence mediators including p38, γ-H2AX, and mTORC1. Taken together, our findings unveil a critical role of the non-classical secretory pathway of IL-1α in cellular senescence and SASP regulation.

A ubiquitin-like domain controls protein kinase D dimerization and activation by trans-autophosphorylation

Protein kinase D (PKD) is an essential Ser/Thr kinase in animals and controls a variety of diverse cellular functions, including vesicle trafficking and mitogenesis. PKD is activated by recruitment to membranes containing the lipid second messenger diacylglycerol (DAG) and subsequent phosphorylation of its activation loop. Here, we report the crystal structure of the PKD N terminus at 2.2 Å resolution containing a previously unannotated ubiquitin-like domain (ULD), which serves as a dimerization domain. A single point mutation in the dimerization interface of the ULD not only abrogated dimerization in cells but also prevented PKD activation loop phosphorylation upon DAG production. We further show that the kinase domain of PKD dimerizes in a concentration-dependent manner and autophosphorylates on a single residue in its activation loop. We also provide evidence that PKD is expressed at concentrations 2 orders of magnitude below the ULD dissociation constant in mammalian cells. We therefore propose a new model for PKD activation in which the production of DAG leads to the local accumulation of PKD at the membrane, which drives ULD-mediated dimerization and subsequent trans-autophosphorylation of the kinase domain.

Doxorubicin-Induced Cancer Cell Senescence Shows a Time Delay Effect and Is Inhibited by Epithelial-Mesenchymal Transition (EMT)

Background

Senescence is a natural barrier for the body to resist the malignant transformation of its own cells. This work investigated the senescence characteristics of cancer cells in vitro.

Material/Methods

Human cervical cancer HeLa cells were treated with different concentrations of doxorubicin for 3 days, with or without subsequent extended culture in drug-free medium for 6 days. Senescent cell ratios between these 2 culture schemes were calculated. Expression of 2 senescence-associated secretory factors, IL-6 and IL-8, were detected by RT-PCR and ELISA. Doxorubicin treatment induced epithelial-mesenchymal transition in cancer cells. The proportions of senescent cells in epithelial-like and mesenchymal-like sub-groups were calculated. Doxorubicin-treated HeLa cells were stained with Vimentin antibody and sorted by flow cytometry. Senescent cell marker p16^INK4a and IL-8 expression in Vimentin-high and Vimentin-low cells were detected by Western blot.

Results

We found that less than 1% of HeLa cells showed senescence phenotype after treatment with doxorubicin for 3 days. However, the proportion of senescent cells was significantly increased when the doxorubicin-treated cells were subsequently cultured in drug-free medium for another 6d. RT-PCR and ELISA results showed that this prolonged culture method could further improve the expression of IL-6 and IL-8. We also found that the senescent cells were mainly epithelial-like type and few presented mesenchymal-like shape. p16^INK4a and IL-8 expression were decreased in cell fraction with higher Vimentin expression.

Conclusions

Our results suggested the existence of time delay effect in doxorubicin-induced senescence of HeLa cells, and epithelial-mesenchymal transition may resist doxorubicin-induced cell senescence.

Paradoxical effects of cellular senescence-inhibited gene involved in hepatocellular carcinoma migration and proliferation by ERK pathway and mesenchymal-like markers

BACKGROUND

Cellular senescence-inhibited gene (CSIG) strongly prolongs the progression of replicative senescence. However, roles and mechanisms of CSIG in tumor progression have not been studied widely.

METHODS

Roles of CSIG in migration and proliferation of SMMC7721 and Huh7 cells were analyzed by transwell or cell viability assays, respectively. Tumorigenicity assays were used to study whether CSIG knockdown could affect SMMC7721 proliferation in vivo. Next, Western blotting and RT-PCR were preformed to evaluate the effects of CSIG on P-ERK cascade and epithelial mesenchymal transformation markers. Then, the location and expression of CSIG protein was detected by immunofluorescence and Western blotting, respectively. Finally, the Cancer Genome Atlas dataset was used to analyze CSIG mRNA levels in hepatocellular carcinoma (HCC) and adjacent non-tumor tissues.

RESULTS

In this study, we found that CSIG overexpression promoted SMMC7721 cell migration, and CSIG knockdown suppressed tumorigenicity of SMMC7721 cells. In contrast to expectation, CSIG up-regulation could significantly inhibit Huh7 cell growth and migration. CSIG could promote P-ERK activation and levels of mesenchymal-like markers in SMMC7721 cells, whereas CSIG suppressed P-ERK activation and levels of mesenchymal-like markers in Huh7 cells. CSIG protein was located in nucleoli as well as nucleoplasm of SMMC7721 cells, whereas CSIG protein was mainly expressed in the nucleoli rather than nucleoplasm of Huh7 cells. Finally, due to individual differences, raised or down-regulated trends of CSIG in HCC as compared with adjacent non-tumor tissues are different among various patient populations.

CONCLUSION

In summary, these results indicate that CSIG might play different roles in SMMC7721 and Huh7 cells through regulating P-ERK pathway and mesenchymal-like markers. The differential distribution of CSIG might be an important factor that causes its different functions in SMMC7721 and Huh7 cells. CSIG might play different roles in various patient populations.

The senescence-associated secretory phenotype and its regulation

The senescence-associated secretory phenotype (SASP) defines the ability of senescent cells to express and secrete a variety of extracellular modulators that includes cytokines, chemokines, proteases, growth factors and bioactive lipids. The role of the SASP depends on the context. The SASP reinforces the senescent cell cycle arrest, stimulates the immune-mediated clearance of potentially tumorigenic cells, limits fibrosis and promotes wound healing and tissue regeneration. On the other hand, the SASP can mediate chronic inflammation and stimulate the growth and survival of tumor cells. The regulation of the SASP occurs at multiple levels including chromatin remodelling, activation of specific transcription factors such as C/EBP and NF-κB, control of mRNA translation and intracellular trafficking. Several SASP modulators have already been identified setting the stage for future research on their clinical applications.

Cellular senescence links aging and diabetes in cardiovascular disease

Aging is a powerful independent risk factor for cardiovascular diseases such as atherosclerosis and heart failure. Concomitant diabetes mellitus strongly reinforces this effect of aging on cardiovascular disease. Cellular senescence is a fundamental mechanism of aging and appears to play a crucial role in the onset and prognosis of cardiovascular disease in the context of both aging and diabetes. Senescent cells are in a state of cell cycle arrest but remain metabolically active by secreting inflammatory factors. This senescence-associated secretory phenotype is a trigger of chronic inflammation, oxidative stress, and decreased nitric oxide bioavailability. A complex interplay between these three mechanisms results in age- and diabetes-associated cardiovascular damage. In this review, we summarize current knowledge on cellular senescence and its secretory phenotype, which might be the missing link between aging and diabetes contributing to cardiovascular disease.

Adeno-associated virus vector-mediated expression of DJ-1 attenuates learning and memory deficits in 2, 2´, 4, 4´-tetrabromodiphenyl ether (BDE-47)-treated mice

Evidence indicates that oxidative stress is the central pathological feature of 2, 2´, 4, 4´-tetrabromodiphenyl ether (BDE-47)-induced neurotoxicity. Protein kinase C delta (PKCδ), an oxidative stress-sensitive kinase, can be proteolytically cleaved to yield a catalytically active fragment (PKCδ-CF) that is involved in various neurodegenerative disorders. Here, we showed that BDE-47 treatment increased ROS, malondialdehyde, and protein carbonyl levels in the mouse hippocampus. In turn, excessive ROS induced caspase-3-dependent PKCδ activation and stimulated NF-κB p65 nuclear translocation, resulting in inflammation in the mouse hippocampus. These changes caused learning and memory deficits in BDE-47-treated mice. Treatment with Z-DEVD-fmk, a caspase-3 inhibitor, or N-acetyl-L-cysteine, an antioxidant, blocked PKCδ activation and subsequently inhibited inflammation, thereby improving learning and memory deficits in BDE-47-treated mice. Our data further showed that activation of ROS-PKCδ signaling was associated with DJ-1 downregulation, which exerted neuroprotective effects against oxidative stress induced by different neurotoxic agents. Adeno-associated viral vector-mediated DJ-1 overexpression in the hippocampus effectively inhibited excessive ROS production, suppressed caspase-3-dependent PKCδ cleavage, blunted inflammation and ultimately reversed learning and memory deficits in BDE-47-treated mice. Taken together, our results demonstrate that DJ-1 plays a pivotal role in BDE-47-induced neurotoxic effects and learning and memory deficits.

The protein kinase D1-mediated classical protein secretory pathway regulates the Ras oncogene-induced senescence response

Senescent cells develop a senescence-associated secretory phenotype (SASP). The factors secreted by cells with a SASP have multiple biological functions that are mediated in an autocrine or paracrine manner. However, the status of the protein kinase D1 (PKD1; also known as PRKD1)-mediated classical protein secretory pathway, from the trans-Golgi network (TGN) to the cell surface, during cellular senescence and its role in the cellular senescence response remain unknown. Here, we show that the activities or quantities of critical components of this pathway, including PKD1, ADP-ribosylation factor 1 (ARF1) and phosphatidylinositol 4-kinase IIIβ (PI4KIIIβ), at the TGN are increased in senescent cells. Blocking of this pathway decreases IL-6 and IL-8 (hereafter IL-6/IL-8) secretion and results in IL-6/IL-8 accumulation in SASP-competent senescent cells. Inhibition of this pathway reduces IL-6/IL-8 secretion during Ras oncogene-induced senescence (OIS), retards Ras OIS and alleviates its associated ER stress and autophagy. Finally, targeting of this pathway triggers cell death in SASP factor-producing senescent cells due to the intracellular accumulation of massive amounts of IL-6/IL-8. Taken together, our results unveil the hyperactive state of the protein secretory pathway in SASP-competent senescent cells and its critical functions in mediating SASP factor secretion and the Ras OIS process, as well as in determining the fate of senescent cells.

NADPH oxidase 4 mediates ROS production in radiation-induced senescent cells and promotes migration of inflammatory cells

Excessive DNA damage induced by ionising radiation (IR) to normal tissue cells is known to trigger cellular senescence, a process termed stress-induced premature senescence (SIPS). SIPS is often accompanied by the production of reactive oxygen species (ROS), and this is reported to be important for the initiation and maintenance of SIPS. However, the source of ROS during SIPS after IR and their significance in radiation-induced normal tissue damage remain elusive. In the present study, we tested the hypothesis that the NADPH oxidase (NOX) family of proteins mediates ROS production in SIPS-induced cells after IR and plays a role in SIPS-associated biological events. X-irradiation of primary mouse embryonic fibroblasts (MEFs) resulted in cellular senescence and the concomitant increase of intracellular ROS. Among all six murine NOX isoforms (NOX1-4 and DUOX1/2), only NOX4 was detectable under basal conditions and was upregulated following IR. In addition, radiation-induced ROS production was diminished by genetic or pharmacological inhibition of NOX4. Meanwhile, NOX4 deficiency did not affect the induction of cellular senescence after IR. Furthermore, the migration of human monocytic U937 cells to the culture medium collected from irradiated MEFs was significantly reduced by NOX4 inhibition, suggesting that NOX4 promotes the recruitment of inflammatory cells. Collectively, our findings imply that NOX4 mediates ROS production in radiation-induced senescent cells and contributes to normal tissue damage after IR via the recruitment of inflammatory cells and the exacerbation of tissue inflammation.

The differential role of reactive oxygen species in early and late stages of cancer

The large doses of vitamins C and E and β-carotene used to reduce reactive oxygen species (ROS) production and oxidative damages in cancerous tissue have produced disappointing and contradictory results. This therapeutic conundrum was attributed to the double-faced role of ROS, notably, their ability to induce either proliferation or apoptosis of cancer cells. However, for a ROS-inhibitory approach to be effective, it must target ROS when they induce proliferation rather than apoptosis. On the basis of recent advances in redox biology, this review underlined a differential regulation of prooxidant and antioxidant system, respective to the stage of cancer. At early precancerous and neoplastic stages, antioxidant activity decreases and ROS appear to promote cancer initiation via inducing oxidative damage and base pair substitution mutations in prooncogenes and tumor suppressor genes, such as RAS and TP53, respectively. Whereas in late stages of cancer progression, tumor cells escape apoptosis by producing high levels of intracellular antioxidants, like NADPH and GSH, via the pentose phosphate pathway to buffer the excessive production of ROS and related intratumor oxidative injuries. Therefore, antioxidants should be prohibited in patients with advanced stages of cancer and/or undergoing anticancer therapies. Interestingly, the biochemical and biophysical properties of some polyphenols allow them to selectively recognize tumor cells. This characteristic was exploited to design and deliver nanoparticles coated with low doses of polyphenols and containing chemotherapeutic drugs into tumor-bearing animals. First results are encouraging, which may revolutionize the conventional use of antioxidants in cancer.

FOXQ1 regulates senescence-associated inflammation via activation of SIRT1 expression

Cellular senescence is an initial barrier to tumor development that prevents the proliferation of premalignant cells. However, some of the features of senescent cells seem to promote tumor progression via senescence-associated secretory phenotype (SASP). Here, we demonstrated that the protein level of forkhead box Q1 (FOXQ1), which highly overexpresses in several kinds of tumors, was significantly downregulated during both replicative and oncogene-induced senescence. Moreover, overexpression of FOXQ1 delayed senescence, whereas FOXQ1 silence led to premature senescence in human fibroblasts. Furthermore, we identified that FOXQ1 upregulated SIRT1 expression through transcriptional regulation via directly binding to the SIRT1 promoter. Finally, we showed that FOXQ1 remarkably inhibited the replicative senescence through depressing the expression of the inflammatory cytokines interleukin-6 (IL-6) and IL-8 via modulation of SIRT1-NF-κB pathway. In addition, FOXQ1 overexpressed in human esophageal cancer cells and ablation of FOXQ1 restrained the tumourigenic ability of the esophageal cancer cells (EC109 and EC9706) in a mouse xenograft model in vivo. Taken together, these findings uncover a previously unidentified role of FOXQ1 regulating SASP and tumor development at same time.

Over Expression of Long Non-Coding RNA PANDA Promotes Hepatocellular Carcinoma by Inhibiting Senescence Associated Inflammatory Factor IL8

It has been reported that long non-coding RNA PANDA was disregulated in varieties types of tumor, but its expression level and biological role in hepatocellular carcinoma (HCC) remains contradictory. We detected PANDA expression in two independent cohorts (48 HCC patients following liver transplantation and 84 HCC patients following liver resection), and found that PANDA was down-regulated in HCC. Thereafter we explored its function in cancer biology by inversing its low expression. Surprisingly, overexpression of PANDA promoted HCC proliferation and carcinogenesis in vitro and in vivo. Mechanistically, PANDA repressed transcriptional activity of senescence associated inflammatory factor IL8, which leaded to inhibition of cellular senescence. Therefore, our research help to better understand the complex role of PANDA in HCC, and suggest more thoughtful strategies should be applied before it can be treated as a potential therapeutic target.

Mitochondrial and Oxidative Stress-Mediated Activation of Protein Kinase D1 and Its Importance in Pancreatic Cancer

Due to alterations in their metabolic activity and decreased mitochondrial efficiency, cancer cells often show increased generation of reactive oxygen species (ROS), but at the same time, to avoid cytotoxic signaling and to facilitate tumorigenic signaling, have mechanism in place that keep ROS in check. This requires signaling molecules that convey increases in oxidative stress to signal to the nucleus to upregulate antioxidant genes. Protein kinase D1 (PKD1), the serine/threonine kinase, is one of these ROS sensors. In this mini-review, we highlight the mechanisms of how PKD1 is activated in response to oxidative stress, so far known downstream effectors, as well as the importance of PKD1-initiated signaling for development and progression of pancreatic cancer.

Methyl caffeate and some plant constituents inhibit age-related inflammation: effects on senescence-associated secretory phenotype (SASP) formation

During aging, cells secrete molecules called senescence-associated secretory phenotype (SASP). They constitute chronic low-grade inflammation environment to adjacent cells and tissues. In order to find inhibiting agents of SASP formation, 113 plant constituents were incubated with BJ fibroblasts for 6 days after treatment with bleomycin. Several plant constituents showed considerable inhibition of IL-6 production, a representative SASP marker. These plant constituents included anthraquinones such as aurantio-obtusin, flavonoids including astragalin, iristectorigenin A, iristectorigenin B, linarin, lignans including lariciresinol 9-O-glucoside and eleutheroside E, phenylpropanoids such as caffeic acid and methyl caffeate, steroid (ophiopogonin), and others like centauroside, rhoifolin and scoparone. In particular, methyl caffeate down-regulated SASP factors such as IL-1α, IL-1β, IL-6, IL-8, GM-CSF, CXCL1, MCP-2, and MMP-3. Inhibition of these SASP mRNA expression levels also coincided with the reduction of IκBζ expression and NF-κB p65 activation without affecting the expression levels of senescence markers, p21 or pRb. Taken together, the present study demonstrated that methyl caffeate might be a specific and strong inhibitor of SASP production without affecting the aging process. Its action mechanisms involve the reduction of IκBζ expression and NF-κB p65 activation. Therefore, this compound might be effective in alleviating chronic low-grade inflammation linked to age-related degenerative disorders.

hnRNP A1 antagonizes cellular senescence and senescence-associated secretory phenotype via regulation of SIRT1 mRNA stability

Senescent cells display a senescence‐associated secretory phenotype (SASP) which contributes to tumor suppression, aging, and cancer. However, the underlying mechanisms for SASP regulation are not fully elucidated. SIRT1, a nicotinamide adenosine dinucleotide‐dependent deacetylase, plays multiple roles in metabolism, inflammatory response, and longevity, etc. However, its posttranscriptional regulation and its roles in cellular senescence and SASP regulation are still elusive. Here, we identify the RNA‐binding protein hnRNP A1 as a posttranscriptional regulator of SIRT1, as well as cell senescence and SASP regulator. hnRNP A1 directly interacts with the 3′ untranslated region of SIRT1 mRNA, promotes its stability, and increases SIRT1 expression. hnRNP A1 delays replicative cellular senescence and prevents from Ras OIS via upregulation of SIRT1 expression to deacetylate NF‐κB, thus blunting its transcriptional activity and subsequent IL‐6/IL‐8 induction. hnRNP A1 overexpression promotes cell transformation and tumorigenesis in a SIRT1‐dependent manner. Together, our findings unveil a novel posttranscriptional regulation of SIRT1 by hnRNP A1 and uncover a critical role of hnRNP A1‐SIRT1–NF‐κB pathway in regulating cellular senescence and SASP expression.

Downregulation of B-myb promotes senescence via the ROS-mediated p53/p21 pathway, in vascular endothelial cells

OBJECTIVES

To reveal whether B-myb is involved in preventing senescence of vascular endothelial cells, and if so, to identify possible mechanisms for it.

MATERIALS AND METHODS

C57/BL6 male mice and primary human aortic endothelial cells (HAECs) were used. Bleomycin was applied to induce stress-related premature senescence. B-myb knockdown was achieved using an siRNA technique and cell senescence was assessed using the senescence-associated β-galactosidase (SA-β-gal) assay. Intracellular reactive oxygen species (ROS) production was analysed using an ROS assay kit and cell proliferation was evaluated using KFluor488 EdU kit. Capillary tube network formation was determined by Matrigel assay. Expressions of mRNA and protein levels were detected by real-time PCR and western blotting.

RESULTS

B-myb expression significantly decreased, while p53 and p21 expressions increased in the aortas of aged mice. This expression pattern was also found in replicative senescent HAECs and senescent HAECs induced by bleomycin. B-myb knockdown resulted in upregulation of p22^phox , ROS accumulation and cell senescence of HAECs. Downregulation of B-myb significantly inhibited cell proliferation and capillary tube network formation and activated the p53/p21 signalling pathway. Blocking ROS production or inhibiting p53 activation remarkably attenuated SA-β-gal activity and delayed cell senescence induced by B-myb-silencing.

CONCLUSION

Downregulation of B-myb induced senescence by upregulation of p22^phox and activation of the ROS/p53/p21 pathway, in our vascular endothelial cells, suggesting that B-myb may be a novel candidate for regulating cell senescence to protect against endothelial senescence-related cardiovascular diseases.

The Senescence-Associated Secretory Phenotype: Critical Effector in Skin Cancer and Aging

Cellular senescence, a state of stable cell cycle arrest in response to cellular stress, is an indispensable mechanism to counter tumorigenesis by halting the proliferation of damaged cells. However, through the secretion of an array of diverse cytokines, chemokines, growth factors, and proteases known as the senescence-associated secretory phenotype (SASP), senescent cells can paradoxically promote carcinogenesis. Consistent with this, removal of senescent cells delays the onset of cancer and prolongs lifespan in vivo, potentially in part through SASP reduction. In this review, we consider the evidence for the SASP and "SASP-like" inflammation in driving skin carcinogenesis, emphasizing how further understanding of both the roles and mechanisms of SASP expression may offer new targets for skin cancer prevention and therapy.

Inflammation Thread Runs across Medical Laboratory Specialities

We work on the assumption that four major specialities or sectors of medical laboratory assays, comprising clinical chemistry, haematology, immunology, and microbiology, embraced by genome sequencing techniques, are routinely in use. Medical laboratory markers for inflammation serve as model: they are allotted to most fields of medical lab assays including genomics. Incessant coding of assays aligns each of them in the long lists of big data. As exemplified with the complement gene family, containing C2, C3, C8A, C8B, CFH, CFI, and ITGB2, heritability patterns/risk factors associated with diseases with genetic glitch of complement components are unfolding. The C4 component serum levels depend on sufficient vitamin D whilst low vitamin D is inversely related to IgG1, IgA, and C3 linking vitamin sufficiency to innate immunity. Whole genome sequencing of microbial organisms may distinguish virulent from nonvirulent and antibiotic resistant from nonresistant varieties of the same species and thus can be listed in personal big data banks including microbiological pathology; the big data warehouse continues to grow.

MLL1 is essential for the senescence-associated secretory phenotype

Capell et al. show that MLL1 inhibition represses expression of critical proproliferative cell cycle regulators required for DNA replication and DNA damage response activation, thus disabling senescence-associated secretory phenotype (SASP) expression. These inhibitory effects of MLL1 on SASP gene expression do not impair oncogene-induced senescence and abolish the ability of the SASP to enhance cancer cell proliferation.

Oncogene-induced senescence (OIS) and therapy-induced senescence (TIS), while tumor-suppressive, also promote procarcinogenic effects by activating the DNA damage response (DDR), which in turn induces inflammation. This inflammatory response prominently includes an array of cytokines known as the senescence-associated secretory phenotype (SASP). Previous observations link the transcription-associated methyltransferase and oncoprotein MLL1 to the DDR, leading us to investigate the role of MLL1 in SASP expression. Our findings reveal direct MLL1 epigenetic control over proproliferative cell cycle genes: MLL1 inhibition represses expression of proproliferative cell cycle regulators required for DNA replication and DDR activation, thus disabling SASP expression. Strikingly, however, these effects of MLL1 inhibition on SASP gene expression do not impair OIS and, furthermore, abolish the ability of the SASP to enhance cancer cell proliferation. More broadly, MLL1 inhibition also reduces “SASP-like” inflammatory gene expression from cancer cells in vitro and in vivo independently of senescence. Taken together, these data demonstrate that MLL1 inhibition may be a powerful and effective strategy for inducing cancerous growth arrest through the direct epigenetic regulation of proliferation-promoting genes and the avoidance of deleterious OIS- or TIS-related tumor secretomes, which can promote both drug resistance and tumor progression.

Cellular Senescence as the Causal Nexus of Aging

In this paper we present cellular senescence as the ultimate driver of the aging process, as a "causal nexus" that bridges microscopic subcellular damage with the phenotypic, macroscopic effect of aging. It is important to understand how the various types of subcellular damage correlated with the aging process lead to the larger, visible effects of anatomical aging. While it has always been assumed that subcellular damage (cause) results in macroscopic aging (effect), the bridging link between the two has been hard to define. Here, we propose that this bridge, which we term the "causal nexus", is in fact cellular senescence. The subcellular damage itself does not directly cause the visible signs of aging, but rather, as the damage accumulates and reaches a critical mass, cells cease to proliferate and acquire the deleterious "senescence-associated secretory phenotype" (SASP) which then leads to the macroscopic consequences of tissue breakdown to create the physiologically aged phenotype. Thus senescence is a precondition for anatomical aging, and this explains why aging is a gradual process that remains largely invisible during most of its progression. The subcellular damage includes shortening of telomeres, damage to mitochondria, aneuploidy, and DNA double-strand breaks triggered by various genetic, epigenetic, and environmental factors. Damage pathways acting in isolation or in concert converge at the causal nexus of cellular senescence. In each species some types of damage can be more causative than in others and operate at a variable pace; for example, telomere erosion appears to be a primary cause in human cells, whereas activation of tumor suppressor genes is more causative in rodents. Such species-specific mechanisms indicate that despite different initial causes, most of aging is traced to a single convergent causal nexus: senescence. The exception is in some invertebrate species that escape senescence, and in non-dividing cells such as neurons, where senescence still occurs, but results in the SASP rather than loss of proliferation plus SASP. Aging currently remains an inevitable endpoint for most biological organisms, but the field of cellular senescence is primed for a renaissance and as our understanding of aging is refined, strategies capable of decelerating the aging process will emerge.

Oncogenic Ras modulates p38 MAPK-mediated inflammatory cytokine production in glioblastoma cells

Inflammation is an important factor promoting the progression of glioblastoma. In the present study we examined the contribution of Ras signaling and TNFα/IL-1β cytokines to the development of the glioblastoma inflammatory microenvironment. Enhanced activation of Ras through de-regulated activation of receptor tyrosine kinases, such as EGFR, PDGFR and cMet, is a hallmark of the majority of glioblastomas. Glioblastoma microenvironment contains high levels of TNFα and IL-1β, which mediate inflammation through induction of a local network of cytokines and chemokines. While many studies have focused on Ras- and TNFα/IL-1β-driven inflammation in isolation, little is known about the co-operation between these oncogenic and microenvironment-derived stimuli. Using constitutively active HRasG12V that mimics enhanced Ras activation, we demonstrate that elevated Ras activity in glioblastoma cells leads to up-regulation of IL-6 and IL-8. Furthermore, Ras synergizes with the microenvironment-derived TNFα and IL-1β resulting in amplified IL-6/IL-8 secretion. IL-8 secretion induced by Ras and TNFα/IL-1β is attenuated by inhibitors targeting Erk, JNK and p38 MAPK pathways. IL-6 secretion significantly decreased upon inhibition of JNK and p38 MAPK pathways. Interestingly, although constitutively active HRasG12V does not increase basal or TNFα/IL-1β stimulated p38 MAPK activity, HRasG12V increased the efficacy of the p38 MAPK inhibitor SB203580 to inhibit IL-1β-induced IL-6 secretion. In summary, oncogenic Ras co-operates with the microenvironment-derived TNFα/IL-1β to sustain inflammatory microenvironment, which was effectively attenuated via inhibition of p38 MAPK signaling.

Attenuation of radiation-induced gastrointestinal damage by epidermal growth factor and bone marrow transplantation in mice

PURPOSE

We examined the effect of epidermal growth factor (EGF) and bone marrow transplantation (BMT) on gastrointestinal damage after high-dose irradiation of mice.

MATERIAL AND METHODS

C57Black/6 mice were used. Two survival experiments were performed (12 and 13 Gy; (60)Co, 0.59-0.57 Gy/min). To evaluate BMT and EGF action, five groups were established - 0 Gy, 13 Gy, 13 Gy + EGF (at 2 mg/kg, first dose 24 h after irradiation and then every 48 h), 13 Gy + BMT (5 × 10(6) cells from green fluorescent protein [GFP] syngenic mice, 4 h after irradiation), and 13 Gy + BMT + EGF. Survival data, blood cell counts, gastrointestine and liver parameters and GFP positive cell migration were measured.

RESULTS

BMT and EGF (three doses, at 2 mg/kg, administered 1, 3 and 5 days after irradiation) significantly increased survival (13 Gy). In blood, progressive cytopenia was observed with BMT, EGF or their combination having no improving effect early after irradiation. In gastrointestinal system, BMT, EGF and their combination attenuated radiation-induced atrophy and increased regeneration during first week after irradiation with the combination being most effective. Signs of systemic inflammatory reaction were observed 30 days after irradiation.

CONCLUSIONS

Our data indicate that BMT together with EGF is a promising strategy in the treatment of high-dose whole-body irradiation damage.

Effects of flavonoids on senescence-associated secretory phenotype formation from bleomycin-induced senescence in BJ fibroblasts

During senescence, cells express molecules called senescence-associated secretory phenotype (SASP), including growth factors, proinflammatory cytokines, chemokines, and proteases. The SASP induces a chronic low-grade inflammation adjacent to cells and tissues, leading to degenerative diseases. The anti-inflammatory activity of flavonoids was investigated on SASP expression in senescent fibroblasts. Effects of flavonoids on SASP expression such as IL-1α, IL-1β, IL-6, IL-8, GM-CSF, CXCL1, MCP-2 and MMP-3 and signaling molecules were examined in bleomycin-induced senescent BJ cells. In vivo activity of apigenin on SASP suppression was identified in the kidney of aged rats. Among the five naturally-occurring flavonoids initially tested, apigenin and kaempferol strongly inhibited the expression of SASP. These flavonoids inhibited NF-κB p65 activity via the IRAK1/IκBα signaling pathway and expression of IκBζ. Blocking IκBζ expression especially reduced the expression of SASP. A structure-activity relationship study using some synthetic flavones demonstrated that hydroxyl substitutions at C-2',3',4',5 and 7 were important in inhibiting SASP production. Finally, these results were verified by results showing that the oral administration of apigenin significantly reduced elevated levels of SASP and IκBζ mRNA in the kidneys of aged rats. This study is the first to show that certain flavonoids are inhibitors of SASP production, partially related to NF-κB p65 and IκBζ signaling pathway, and may effectively protect or alleviate chronic low-grade inflammation in degenerative diseases such as cardiovascular diseases and late-stage cancer.

Chlorogenic acid inhibits hypoxia-induced angiogenesis via down-regulation of the HIF-1α/AKT pathway

BACKGROUND

The hypoxia-inducible factor-1 (HIF-1) is known to play an important role in cellular responses to hypoxia, including the transcriptional activation of a number of genes involved in tumor angiogenesis. Chlorogenic acid (CGA), one of the most abundant polyphenols in the human diet, has been reported to inhibit cancer cell growth. The effect of CGA on tumor angiogenesis and its underlying mechanisms are, as yet, unknown.

METHODS

The effect of CGA on HIF-1α expression was assessed by Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR) assays in A549 lung cancer cells. The transcriptional activity of the HIF-1 complex was confirmed using a luciferase assay. To assess whether angiogenic factors are increased under hypoxic conditions in these cells, vascular endothelial growth factor (VEGF) expression levels were measured by RT-PCR and Western blotting. The direct effect of CGA on human vascular endothelial cells (HUVEC) under hypoxic conditions was analyzed using in vitro assays, including tube-formation, wound healing and Transwell invasion assays. To investigate the effect of CGA on angiogenesis in vivo, we performed a Matrigel plug assay in a mouse model. Finally, the effect of CGA on AKT and ERK activation (phosphorylation) as a putative mechanism underlying the effect of CGA on VEGF-mediated angiogenesis inhibition was assessed using Western blotting.

RESULTS

We found that CGA significantly decreases the hypoxia-induced HIF-1α protein level in A549 cells, without changing its mRNA level. CGA was, however, found to suppress the transcriptional activity of HIF-1α under hypoxic conditions, leading to a decrease in the expression of its downstream target VEGF. We also found that CGA can block hypoxia-stimulated angiogenesis in vitro and VEGF-stimulated angiogenesis in vivo using HUVEC cells. In addition, we found that CGA can inhibit the HIF-1α/AKT signaling pathway, which plays an important role in VEGF activation and angiogenesis.

CONCLUSIONS

Our data indicate that CGA plays a role in the suppression of angiogenesis via inhibition of the HIF-1α/AKT pathway. CGA may represent a novel therapeutic option for the treatment of (lung) cancer.