Pro-inflammatory cytokines mediating senescence of vascular endothelial cells in atherosclerosis.

Atherosclerosis (AS) is a chronic inflammatory vascular disease, and aging is a major risk factor. The accumulation of senescent vascular endothelial cells (VECs) often leads to chronic inflammation and oxidative stress and induces endothelial dysfunction, contributing to the occurrence and development of AS. Senescent cells can secrete a variety of pro-inflammatory cytokines to induce the senescence of adjacent cells in a paracrine manner, leading to the transmission of signaling of cellular senescence to neighboring cells and the accumulation of senescent cells. Recent studies have demonstrated that several pro-inflammatory cytokines, including IL-17, TNF-α, and IFN-γ, can induce the senescence of VECs. This review summarizes and focuses on the pro-inflammatory cytokines that often induce the senescence of VECs and the molecular mechanisms of these pro-inflammatory cytokines inducing senescence of VECs. Targeting the senescence of VECs induced by pro-inflammatory cytokines may provide a potential and novel strategy for the prevention and treatment of AS.

Inhibitory effects and molecular mechanisms of ginsenoside Rg1 on the senescence of hematopoietic stem cells.

Hematopoietic stem cells (HSCs) produce all blood cell lineages and maintain life-long hematopoiesis. However, the self-renewal ability and differentiation capacity of HSCs reduces with age. The senescence of HSCs can lead to the imbalance of hematopoietic homeostasis and immune disorder and induce a variety of age-related diseases. Recent studies have shown that therapeutic interventions targeting the senescence of HSCs may prevent disease progression. Ginsenoside Rg1 (Rg1), extracted from roots or stems of ginseng, has beneficial antiaging activities. It has been reported that Rg1 can inhibit the senescence of HSCs. Here, we reviewed recent advances of Rg1 in inhibiting the senescence of HSCs and discussed related molecular mechanisms. Bioinformatics and network databases have been widely applied to drug discoveries. Here, we predicted potential antiaging targets of Rg1 explored by bioinformatic methods, which may help discover new targets of Rg1 and provide novel strategies for delaying the aging process of HSCs.

Therapeutic targeting of DNA damage repair pathways guided by homologous recombination deficiency scoring in ovarian cancers.

The susceptibility of cells to DNA damage and their DNA repair ability are crucial for cancer therapy. Homologous recombination is one of the major repairing mechanisms for DNA double-strand breaks. Approximately half of ovarian cancer (OvCa) cells harbor homologous recombination deficiency (HRD). Considering that HRD is a major hallmark of OvCas, scholars proposed HRD scoring to evaluate the HRD degree and guide the choice of therapeutic strategies for OvCas. In the last decade, synthetic lethal strategy by targeting poly (ADP-ribose) polymerase (PARP) in HR-deficient OvCas has attracted considerable attention in view of its favorable clinical effort. We therefore suggested that the uses of other DNA damage/repair-targeted drugs in HR-deficient OvCas might also offer better clinical outcome. Here, we reviewed the current small molecule compounds that targeted DNA damage/repair pathways and discussed the HRD scoring system to guide their clinical uses.

Molecular dissection on inhibition of Ras-induced cellular senescence by small t antigen of SV40.

Simian virus 40 (SV40) is a potentially oncogenic virus of monkey origin. Transmission, prevalence, and pathogenicity rates of SV40 are unclear, but infection can occur in humans, for example individuals with high contact with rhesus macaques and individuals that received contaminated early batches of polio vaccines in 1950-1963. In addition, several human polyomaviruses, proven carcinogenic, are also highly common in global populations. Cellular senescence is a major mechanism of cancer prevention in vivo. Hyperactivation of Ras usually induces cellular senescence rather than cell transformation. Previous studies suggest small t antigen (ST) of SV40 may interfere with cellular senescence induced by Ras. In the current study, ST was demonstrated to inhibit Ras-induced cellular senescence (RIS) and accumulation of DNA damage in Ras-activated cells. In addition, ST suppressed the signal transmission from BRaf to MEK and thus blocked the downstream transmission of the activated Ras signal. B56γ knockdown mimicked the inhibitory effects of ST overexpression on RIS. Furthermore, KSR1 knockdown inhibited Ras activation and the subsequent cellular senescence. Further mechanism studies indicated that the phosphorylation level of KSR1 rather than the levels of the total protein regulates the activation of Ras signaling pathway. In sum, ST inhibits the continuous hyperactivation of Ras signals by interfering with the normal functions of PP2A-B56γ of dephosphorylating KSR1, thus inhibiting the occurrence of cellular senescence. Although the roles of SV40 in human carcinogenesis are controversial so far, our study has shown that ST of polyomaviruses has tumorigenic potential by inhibiting oncogene-induced senescence (OIS) as a proof of concept.

Interleukin-1ß Drives Cellular Senescence of Rat Astrocytes Induced by Oligomerized Amyloid ß Peptide and Oxidative Stress.

Background: Alzheimer's disease (AD) is the leading cause of dementia. With no reliable treatment that delays or reverses the progress of AD, effective medical drugs, and interventions for AD treatment are in urgent need. Clinical success for patients thus relies on gaining a clearer understanding of AD pathogenesis to feed the development of novel and potent therapy strategies. It is well-established that inflammatory processes are involved in the pathology of AD, and recent studies implicated senescence of glial cells as an important player in the progression of AD. Methods: We did a preliminary screen in rat astrocytes for the five most abundant inflammatory factors in neuroinflammation, namely IL-1ß, IL-6, IL-8, TGF-ß1, and TNF-α, and found that IL-1ß could efficiently induce cellular senescence. After that, SA-ß-gal staining, immunofluorescence, ELISA, qRT-PCR, and immunoblotting were used to explore the underlying mechanism through which IL-1ß mediates cellular senescence of rat astrocytes. Results: IL-1ß-induced cellular senescence of rat astrocytes was accompanied by increased total and phosphorylated tau. Further experiments showed that both oligomerized amyloid ß (Aß) and H2O2 treatment can induce cellular senescence in rat astrocytes and increase the production and secretion of IL-1ß from these cells. Subsequent mechanistic study revealed that activation of NLRP3 mediates Aß and H2O2-induced maturation and secretion of IL-1ß. Conclusion: Our results suggest that IL-1ß mediates senescence in rat astrocytes induced by several common adverse stimuli in AD, implicating IL-1ß and NLRP3 as valuable diagnostic biomarkers and therapeutic targets for AD.

Activation of epidermal growth factor receptor signaling mediates cellular senescence induced by certain pro-inflammatory cytokines.

It is well established that inflammation in the body promotes organism aging, and recent studies have attributed a similar effect to senescent cells. Considering that certain pro-inflammatory cytokines can induce cellular senescence, systematically evaluating the effects of pro-inflammatory cytokines in cellular senescence is an important and urgent scientific problem, especially given the ongoing surge in aging human populations. Treating IMR90 cells and HUVECs with pro-inflammatory cytokines identified six factors able to efficiently induce cellular senescence. Of these senescence-inducing cytokines, the activity of five (namely IL-1ß, IL-13, MCP-2, MIP-3α, and SDF-1α) was significantly inhibited by treatment with cetuximab (an antibody targeting epidermal growth factor receptor [EGFR]), gefitinib (a small molecule inhibitor of EGFR), and EGFR knockdown. In addition, treatment with one of the senescence-inducing cytokines, SDF-1α, significantly increased the phosphorylation levels of EGFR, as well as Erk1/2. These results suggested that pro-inflammatory cytokines induce cellular senescence by activating EGFR signaling. Next, we found that EGF treatment could also induce cellular senescence of IMR90 cells and HUVECs. Mechanically, EGF induced cellular senescence via excessive activation of Ras and the Ras-BRaf-Erk1/2 signaling axis. Moreover, EGFR activation induced IMR90 cells to secrete certain senescence-associated secretory phenotype factors (IL-8 and MMP-3). In summary, we report that certain pro-inflammatory cytokines induce cellular senescence through activation of the EGFR-Ras signaling pathway. Our study thus offers new insight into a long-ignored mechanism by which EGFR could regulate cellular senescence and suggests that growth signals themselves may catalyze aging under certain conditions.

4,5-Diphenyl-2-methyl picolinate induces cellular senescence by accumulating DNA damage and activating associated signaling pathways in gastric cancer.

AIMS: Gastric cancer (GC) is a common cancer with a relatively low survival rate. Cellular senescence, a potent anti-cancer mechanism, is naturally occurred, and can be induced by chemotherapeutic agents. We sought to explore new compounds against GC cells by inducing cellular senescence. MAIN METHODS: Primary screening of a library of N-heterocyclic compounds identified some with potent inhibitory effects on GC cells. Furthermore, in vitro effects of the most potent candidate compound on the proliferation and senescence of GC cells were studied by classical assays, including senescence-associated (SA)-ß-galactosidase staining, and immunofluorescence; and in vivo effects of this compound was evaluated in a xenograft tumor mouse model. KEY FINDINGS: Among 43 tested compounds, 4,5-diphenyl-2-methyl picolinate (DMP) showed the highest inhibition effects on the growth of GC cells. In vitro experiments showed that DMP inhibited the proliferation by inducing senescence and DNA-damage associated protein markers and signaling pathways. In vivo experiment confirmed that DMP treatment inhibited tumor growth by promoting DNA-damage signaling. SIGNIFICANCE: This study set up a platform to identify senescence-inducing anti-cancer compounds, and uncovers that DMP exerted anticancer effects by inducing cellular senescence through targeting DNA damage and associated signaling pathways in GC cancer.

NOD-like receptor signaling in inflammation-associated cancers: From functions to targeted therapies.

BACKGROUND: Recently, many studies have reported that some botanicals and natural products were able to regulate NOD-like receptor signaling. NOD-like receptors (NLRs) have been established as crucial regulators in inflammation-associated tumorigenesis, angiogenesis, cancer cell stemness and chemoresistance. NLRs specifically sense pathogen-associated molecular patterns and respond by activating other signaling regulators, including Rip2 kinase, NF-κB, MAPK and ASC/caspase-1, leading to the secretion of various cytokines. PURPOSE: The aim of this article is to review the molecular mechanisms of NOD-like receptor signaling in inflammation-associated cancers and the NLRs-targeted botanicals and synthetic small molecules in cancer intervention. RESULTS: Aberrant activation of NLRs occurs in various cancers, orchestrating the tissue microenvironment and potentiating neoplastic risk. Blocking NLR inflammasome activation by botanicals or synthetic small molecules may be a valuable way to prevent cancer progression. Moreover, due to the roles of NLRs in regulating cytokine production, NLR signaling may be correlated with senescence-associated secretory phenotype. CONCLUSION: In this review, we discuss how NLR signaling is involved in inflammation-associated cancers, and highlight the NLR-targeted botanicals and synthetic small molecules in cancer intervention.

Circular RNAs in hepatocellular carcinoma: Biomarkers, functions and mechanisms.

Hepatocellular carcinoma (HCC), a leading cause of cancer-related death with high invasive and metastatic potential, has a low survival rate. To improve the survival and quality of life in HCC patients, it is urgently needed to explore novel biomarkers for early diagnosis and prognosis of HCC, as well as therapeutic strategies. Circular RNAs (circRNAs) are a class of highly conserved, stable and abundant non-coding RNAs (ncRNAs) that can regulate gene expression at transcriptional or post-transcriptional levels. Recently, some circRNAs are identified to be potential biomarkers for HCC diagnosis and prognosis. Furthermore, some circRNAs are found to play oncogenic or suppressive roles in HCC progression by regulating various biological processes, including cell proliferation, migration, invasion and metastasis, epithelial-mesenchymal transition (EMT), as well as apoptosis. In this review, we summarize recent findings of deregulated circRNAs, their functions and molecular mechanisms in HCC, and discuss their potential roles as diagnostic biomarkers, prognostic biomarkers, as well as therapeutic targets for HCC.

Poly (ADP-ribose) polymerase inhibitors combined with other small-molecular compounds for the treatment of ovarian cancer.

Ovarian cancer is a heterogeneous disease with complex molecular and genetic hallmarks. Benefitting from profound understanding of molecular mechanisms in ovarian cancer pathogenesis, novel targeted drugs have been actively explored in preclinical studies and clinical trials. Considered as one of the most potent and effective targeted therapies for the treatment of ovarian cancer, poly (ADP-ribose) polymerase (PARP) inhibitors (PARPis) take advantages of synthetic lethality mechanisms to prevent DNA damage repair in cancer cells and cause their death, especially in cancers with BRCA mutations. Mounting evidence has indicated that the combination of PARPis with cytotoxic drugs or other targeted drugs has shown favorable synergistic effects. Excitingly, the antitumor activity of combination therapy of PARPis has been actively tested in multiple clinical trials and in-vitro or in-vivo experiments. In this review, we will briefly discuss the molecular mechanisms of PARPis combined with other therapeutic small-molecular compounds for the treatment of ovarian cancer.

Cellular Senescence-Inducing Small Molecules for Cancer Treatment.

Recently, the chemotherapeutic drug-induced cellular senescence has been considered a promising anti-cancer approach. The drug-induced senescence, which shows both similar and different hallmarks from replicative and oncogene-induced senescence, was regarded as a key determinant of tumor response to chemotherapy in vitro and in vivo. To date, an amount of effective chemotherapeutic drugs that can evoke senescence in cancer cells have been reported. The targets of these drugs differ substantially, including senescence signaling pathways, DNA replication process, DNA damage pathways, epigenetic modifications, microtubule polymerization, senescence-associated secretory phenotype (SASP), and so on. By summarizing senescence-inducing small molecule drugs together with their specific traits and corresponding mechanisms, this review is devoted to inform scientists to develop novel therapeutic strategies against cancer through inducing senescence.

Targeting Membrane Receptors of Ovarian Cancer Cells for Therapy.

Ovarian cancer is a leading cause of death worldwide from gynecological malignancies, mainly because there are few early symptoms and the disease is generally diagnosed at an advanced stage. In addition, despite the effectiveness of cytoreductive surgery for ovarian cancer and the high response rates to chemotherapy, survival has improved little over the last 20 years. The management of patients with ovarian cancer also remains similar despite studies showing striking differences and heterogeneity among different subtypes. It is therefore clear that novel targeted therapeutics are urgently needed to improve clinical outcomes for ovarian cancer. To that end, several membrane receptors associated with pivotal cellular processes and often aberrantly overexpressed in ovarian cancer cells have emerged as potential targets for receptor-mediated therapeutic strategies including specific agents and multifunctional delivery systems based on ligand-receptor binding. This review focuses on the profiles and potentials of such strategies proposed for ovarian cancer treatment and imaging.

Identification of a pyridine derivative inducing senescence in ovarian cancer cell lines via P21 activation.

Cellular senescence is a state of irreversible cell growth arrest. Increasing evidence suggests that cellular senescence contribute to tumour suppression in vivo. However, only a few anti-cancer drugs have been discovered to induce cellular senescence. Searching for new compounds which can inhibit cancer cell growth by inducing senescence is becoming one of the most attractive research fields. To test the effects of candidate compounds on cancer cell growth, cell proliferation assays, senescence-associated ß-galactosidase (SA-ß-gal) staining, and flow cytometry assay were performed. Immunofluorescence, western blot, and qRT-PCR experiments were used to further study the molecular mechanisms of the candidate compounds. We demonstrated that a pyridine derivative, 4-(4-fluorophenyl)-2-phenyl-5, 6, 7, 8-tetrahydroquinoline (FPTHQ), from a pool of 46 compounds can induce senescence of ovarian cancer cells in a dose-dependent manner. FPTHQ caused growth inhibition by inducing G0/G1 cell cycle arrest in A2780 cells. Increased activities of SA-ß-gal were observed in FPTHQ-treated A2780, OVCAR-3 and SKOV-3 cell lines. In addition, FPTHQ treatment increased the protein levels of MMP3 and the mRNA levels of IL-6 and IL-8 in A2780 cells, indicating the appearance of senescence-associated secretary phenotype (SASP) in the cells. Furthermore, we found that p21 was up-regulated and DNA damage was accumulated in FPTHQ-treated ovarian cancer cells. So far, our data suggest that FPTHQ can induce senescence in multiple ovarian cancer cell lines through activation of p21 signalling pathway by causing excessive DNA damage.

Roles of partitioning-defective protein 6 (Par6) and its complexes in the proliferation, migration and invasion of cancer cells.

A pivotal regulator of cell polarity and homeostasis, partitioning-defective protein 6 (Par6) forms multicomponent complexes that not only regulate cell polarity and stabilize cell morphology, but have also been demonstrated to participate in the proliferation, migration and invasion of cancer cells. The transforming growth factor (TGF)-ß and extracellular signal-regulated kinase (Erk) 1/2 pathways are the most thoroughly studied pathways involving Par6 in many cancers. Aurothiomalate has been used to disrupt the interaction between Par6 and atypical protein kinase C within the multicomponent complexes, and has been shown to effectively block transformed growth and metastasis in vitro and/or in vivo in a variety of cancers, including pancreatic, prostate and lung cancers, as well as alveolar rhabdomyosarcoma. It is likely that with further revelations regarding the critical roles of Par6 in cancer initiation, progression and metastasis, targeted therapies against Par6 will be discovered and prove effective preclinically, and hopefully clinically, in cancer treatment.

Heparin-Binding Epidermal Growth Factor-Like Growth Factor as a Potent Target for Breast Cancer Therapy.

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) belongs to the EGF family and exhibits its activity after binding to its receptors in autocrine, paracrine, and juxtacrine interactions. HB-EGF plays important roles in several biological and pathological processes, such as wound healing, blastocyst implantation, atherosclerosis, and heart development. Clinical studies have shown that HB-EGF is closely correlated with tumorigenesis, metastasis, and drug resistance in breast cancer. Specifically, targeted inhibition of HB-EGF improves the therapeutic efficacy and suppresses the tumor progression. This review discusses the importance of HB-EGF in mammary carcinoma progression and the potential value of HB-EGF as a therapeutic target for breast cancer treatment.