Arsenite induces premature senescence via p53/p21 pathway as a result of DNA damage in human malignant glioblastoma cells

Natural flavonoids alleviate glioblastoma multiforme by regulating long non-coding RNA

Glioblastoma multiforme (GBM) is one of the most common primary malignant brain tumors in adults. Due to the poor prognosis of patients, the median survival time of GBM is often less than 1 year. Therefore, it is very necessary to find novel treatment options with a good prognosis for the treatment or prevention of GBM. In recent years, flavonoids are frequently used to treat cancer. It is a new attractive molecule that may achieve this promising treatment option. Flavonoids have been proved to have many biological functions, such as antioxidation, prevention of angiogenesis, anti-inflammation, inhibition of cancer cell proliferation, and protection of nerve cells. It has also shown the ability to regulate long non-coding RNA (LncRNA). Studies have confirmed that flavonoids can regulate epigenetic modification, transcription, and change microRNA (miRNA) expression of GBM through lncRNA at the gene level. It also found that flavonoids can induce apoptosis and autophagy of GBM cells by regulating lncRNA. Moreover, it can improve the metabolic abnormalities of GBM, interfere with the tumor microenvironment and related signaling pathways, and inhibit the angiogenesis of GBM cells. Eventually, flavonoids can block the tumor initiation, growth, proliferation, differentiation, invasion, and metastasis. In this review, we highlight the role of lncRNA in GBM cancer progression and the influence of flavonoids on lncRNA regulation. And emphasize their expected role in the prevention and treatment of GBM.

Inorganic arsenic exposure-induced premature senescence and senescence-associated secretory phenotype (SASP) in human hepatic stellate cells

Exposure to inorganic arsenic has been known to induce cancers in various organs, however, the underlying mechanisms remain unclear. Premature senescence refers to the irreversible growth arrest induced by stress stimuli. The senescence-associated secretory phenotype (SASP), particularly in fibroblasts, has been shown to promote cancer development. In this study, we examined whether arsenite exposure causes premature senescence and induction of SASP in liver fibroblasts using the human hepatic stellate cell line, LX-2. Exposure of LX-2 cells to 5 or 7.5 μM of sodium arsenite for 144 h induced the features of senescence in the cells, including morphological changes, growth inhibition, increased senescence-associated β-galactosidase activity, increased P21 gene expression, and decreased LAMINB1 gene expression. The mRNA expressions of SASP factors, such as MMP1, MMP3, IL-8, IL-1β, and CXCL1, were also highly upregulated. The wound healing assay revealed that the conditioned medium from LX-2 cells with arsenite-induced senescence increased the migration activity of cells of the human hepatoma cell line, Huh-7. Gene expression data of liver cancer samples from the Human Protein Atlas showed that high expression levels of the SASP factors that were upregulated in the cells with arsenite-induced senescence were strongly associated with a poor prognosis. In addition, the cellular levels of γ-H2AX, a DNA double-strand break marker, were increased by arsenite exposure, suggesting that DNA damage could contribute to premature senescence induction. These results show that arsenite exposure induces premature senescence in hepatic stellate cells and suggest that the SASP factors from the senescent cells promote hepatic carcinogenesis.

Modulation of DNA Damage Response by Sphingolipid Signaling: An Interplay that Shapes Cell Fate

Although once considered as structural components of eukaryotic biological membranes, research in the past few decades hints at a major role of bioactive sphingolipids in mediating an array of physiological processes including cell survival, proliferation, inflammation, senescence, and death. A large body of evidence points to a fundamental role for the sphingolipid metabolic pathway in modulating the DNA damage response (DDR). The interplay between these two elements of cell signaling determines cell fate when cells are exposed to metabolic stress or ionizing radiation among other genotoxic agents. In this review, we aim to dissect the mediators of the DDR and how these interact with the different sphingolipid metabolites to mount various cellular responses.

A polyherbal formulation, HC9 regulated cell growth and expression of cell cycle and chromatin modulatory proteins in breast cancer cell lines

ETHNOPHARMACOLOGICAL RELEVANCE

HC9, a polyherbal formulation, is based upon a traditional Ayurvedic formulation, Stanya Shodhana Kashaya (SSK, having 10 plant materials), formulated on Stanyashodhana gana, explained by Charaka in Charakasaṃhita Sutrasthana IV and mentioned in other texts as well. Stanyasodhana is the Sanskrit name for a group of medicinal plants, classified for "improving the quality of milk". SSK is used by Ayurvedic practitioners for the cleansing and detoxification of breast milk in lactating mothers as well as for the management of various clinical conditions. HC9 is composed of equal ratios of nine different medicinal plants that include Picrorhiza kurroa Royle ex Benth., Cyperus rotundus L., Zingiber officinale Roscoe, Cedrus deodara (Roxb. ex D.Don) G.Don, Tinospora cordifolia (Willd.) Miers, Holarrhena antidysenterica (Roth) Wall. ex A.DC., Swertia chirata Buch.-Ham. ex Wall., Cissampelos pareira L. and Hemidesmus indicus (L.) R. Br. ex Schult.. It differs from the SSK formulation by having one ingredient [Marsdenia tenacissima (Roxb.)Moon (Murva)] less, due to its unavailability since it is mostly found in tropical hilly tracts of peninsular India and Vindhya ranges as well as in lower Himalayan tracts. All the medicinal plants in the formulation have reported activity against different types of cancers.

AIM OF THE STUDY

The present study is aimed at evaluating the anticancer activity of the polyherbal formulation (HC9) and its mechanism of action against breast cancer cell lines.

MATERIALS AND METHODS

The effect of HC9 on the viability of breast cancer (MCF-7 and MDAMB231) and non-cancerous (MCF-10A) cell lines was evaluated by MTT assay. The effect on cell growth and colony formation potential of cancer cells was determined by trypan blue dye exclusion method and soft agar assay, respectively. Cell cycle arrest was determined by propidium iodide (PI) staining and analyzed by flowcytometer. Scratch wound assay was used for studying cell migration. Cell invasion was determined by using BD BioCoat Matrigel invasion chambers. The gene expression of HIF-1α was examined by RT-PCR. The expression of p53, SMAR1, p16, MMP-2, CDP/Cux, p21, Rb, phospo-Rb (ppRb), VEGF, NFқB and COX-2 proteins was determined by western blotting.

RESULTS

HC9 significantly altered growth of breast cancer cell lines, MCF-7 and MDA MB-231. It blocked the cell cycle progression at S phase in MCF-7 by up regulating the expression of p53, p21 and p16 proteins. In MDA MB-231, HC9 induced G1 phase arrest by up regulating the expression of p53, p21 and pRb proteins with simultaneous decrease in ppRb. It significantly reduced migration and invasion in both the cell lines, accompanied by decrease in the expression of MMP-2/9, HIF-1α and VEGF. HC9 decreased the expression of inflammatory markers (NF-қB, COX-2), and modulated the expression of chromatin modulators (SMAR1 and CDP/Cux) in both MCF-7 and MDA MB-231.

CONCLUSIONS

HC9 exhibited potent anticancer activity against breast cancer cells, thereby warranting further pre-clinical and clinical studies in future.

Par-4-dependent p53 up-regulation plays a critical role in thymoquinone-induced cellular senescence in human malignant glioma cells

Thymoquinone (TQ), the predominant bioactive constituent present in black cumin (Nigella sativa), exerts tumor suppressive activity against a wide variety of cancer cells. Cellular senescence, characterized by stable and long term loss of proliferative capacity, acts as a potent tumor suppressive mechanism. Here, we provide evidence for the first time that TQ suppresses growth of glioma cells by potentially inducing the expression of prostate apoptosis response-4 (Par-4) tumor suppressor protein. In turn, TQ-induced Par-4 expression triggers cellular senescence, as evidenced by increasing cellular size, β-galactosidase staining, G1 phase arrest, and increased expression of senescence markers such as p53, p21, Rb, and decreased expression of lamin B1, cyclin E and cyclin depended kinase-2 (CDK-2). Further, overexpression of Par-4 significantly increases the expression of p53 and its downstream target p21, and increases β-galactosidase positive cells, while siRNA/shRNA mediated-knockdown of Par-4 reverses the TQ-induced effects. Altogether, we describe a novel mechanism of cross talk between Par-4 and p53, that plays a critical role in TQ-induced senescence in human malignant glioma cells.

An Interplay between Senescence, Apoptosis and Autophagy in Glioblastoma Multiforme-Role in Pathogenesis and Therapeutic Perspective

Autophagy, cellular senescence, programmed cell death and necrosis are key responses of a cell facing a stress. These effects are partly interconnected, but regulation of their mutual interactions is not completely clear. That regulation seems to be especially important in cancer cells, which have their own program of development and demand more nutrition and energy than normal cells. Glioblastoma multiforme (GBM) belongs to the most aggressive and most difficult to cure cancers, so studies on its pathogenesis and new therapeutic strategies are justified. Using an animal model, it was shown that autophagy is required for GBM development. Temozolomide (TMZ) is the key drug in GBM chemotherapy and it was reported to induce senescence, autophagy and apoptosis in GBM. In some GBM cells, TMZ induces small toxicity despite its significant concentration and GBM cells can be intrinsically resistant to apoptosis. Resveratrol, a natural compound, was shown to potentiate anticancer effect of TMZ in GBM cells through the abrogation G2-arrest and mitotic catastrophe resulting in senescence of GBM cells. Autophagy is the key player in TMZ resistance in GBM. TMZ can induce apoptosis due to selective inhibition of autophagy, in which autophagic vehicles accumulate as their fusion with lysosomes is blocked. Modulation of autophagic action of TMZ with autophagy inhibitors can result in opposite outcomes, depending on the step targeted in autophagic flux. Studies on relationships between senescence, autophagy and apoptosis can open new therapeutic perspectives in GBM.

Aloe-emodin (AE) nanoparticles suppresses proliferation and induces apoptosis in human lung squamous carcinoma via ROS generation in vitro and in vivo

Human lung squamous cell carcinoma is a deadly cancer for which present therapeutic strategies are inadequate. And traditional chemotherapy results in severe systemic toxicity. Compounds from living organisms often exert a biological activity, triggering several targets, which may be useful for the improvement of novel pharmaceuticals. Aloe-emodin (AE), a well-known natural compound, is a primary component of anthraquinones in Aloe vera and exhibits anti-proliferative and apoptotic effects on various tumor cells. However, the translational and clinical use of AE has been limited owing to its rapid degradation and poor bioavailability. To improve its efficacy, a poly (lactic-co-glycolic acid) based AE nanoparticle formulation (NanoAE) was prepared. Our study indicated that compared to the free AE, nanoAE significantly suppressed cancer cell proliferation, induced cell cycle arrest and apoptosis, evidenced by high cleavage of Caspase-3, poly (ADP-ribose) polymerase (PARP), Caspase-8 and Caspase-9. NanoAE enhanced reactive oxygen species (ROS) production, along with Mitogen-activated protein kinases (MAPKs) activation and PI3K/AKT inactivation. Cell proliferation, apoptosis and MAPKs and PI3K/AKT were dependent on ROS production in nanoAE-treated groups. In vivo, nanoAE exhibited inhibitory effects on the tumor growth with little toxicity. Together, our results indicated that nanoAE might be an effective treatment for human lung squamous cell carcinoma.

Teng-Long-Bu-Zhong-Tang induces p21-dependent cell senescence in colorectal carcinoma LS174T cells via histone acetylation

Teng-Long-Bu-Zhong-Tang (TLBZT) is a Chinese herbal formula for colorectal carcinoma treatment. TLBZT effectively induces cell senescence in colorectal carcinoma, accompanied by p21 upregulation. In this study, we further explored the role of p21 in TLBZT-induced cell senescence, as well as the mechanism by which TLBZT upregulates p21. Specific knockdown of p21 expression by small interfering RNA significantly attenuated TLBZT-induced cell senescence in human colorectal carcinoma LS174T cells. Silencing of p53 by small interfering RNA did not affect TLBZT-induced p21 upregulation. Meanwhile, TLBZT inhibited histone deacetylase activity. Furthermore, TLBZT increased acetylation levels of histone H3 and H4, enhancing their binding to the p21 promoter. These data suggested that TLBZT induces cell senescence in LS174T cells through a mechanism involving p21 upregulation via histone H3 and H4 acetylation. This study provides new insights into the application of TLBZT for colorectal carcinoma treatment.

Relation Between Cellular Senescence and Liver Diseases

Cellular senescence refers to a process that cellular proliferation and differentiation modulated by the multiple stimulating factors gradually decline. Aging cells present the irreversible stop of proliferation and differentiation and change in secretory function because the cell cycle of aging cells is steadily blocked at some point. It has have been shown that cellular senescence plays an important role in the occurrence and development of liver diseases. In this paper, we review the advances in relations between cellular senescence and liver diseases.

Tat-ATOX1 inhibits streptozotocin-induced cell death in pancreatic RINm5F cells and attenuates diabetes in a mouse model

Antioxidant 1 (ATOX1) functions as an antioxidant against hydrogen peroxide and superoxide, and therefore may play a significant role in many human diseases, including diabetes mellitus (DM). In the present study, we examined the protective effects of Tat-ATOX1 protein on streptozotocin (STZ)-exposed pancreatic insulinoma cells (RINm5F) and in a mouse model of STZ-induced diabetes using western blot analysis, immunofluorescence staining and MTT assay, as well as histological and biochemical analysis. Purified Tat-ATOX1 protein was efficiently transduced into RINm5F cells in a dose- and time-dependent manner. Additionally, Tat-ATOX1 protein markedly inhibited reactive oxygen species (ROS) production, DNA damage and the activation of Akt and mitogen activated protein kinases (MAPKs) in STZ-exposed RINm5F cells. In addition, Tat-ATOX1 protein transduced into mice pancreatic tissues and significantly decreased blood glucose and hemoglobin A1c (HbA1c) levels as well as the body weight changes in a model of STZ-induced diabetes. These results indicate that transduced Tat-ATOX1 protein protects pancreatic β-cells by inhibiting STZ-induced cellular toxicity in vitro and in vivo. Based on these findings, we suggest that Tat-ATOX1 protein has potential applications as a therapeutic agent for oxidative stress-induced diseases including DM.

Beneficial effects of fermented black ginseng and its ginsenoside 20(S)-Rg3 against cisplatin-induced nephrotoxicity in LLC-PK1 cells

Background

Nephrotoxicity is a common side effect of medications. Panax ginseng is one of the best-known herbal medicines, and its individual constituents enhance renal function. Identification of its efficacy and mechanisms of action against drug-induced nephrotoxicity, as well as the specific constituents mediating this effect, have recently emerged as an interesting research area focusing on the kidney protective efficacy of P. ginseng.

Methods

The present study investigated the kidney protective effect of fermented black ginseng (FBG) and its active component ginsenoside 20(S)-Rg3 against cisplatin (chemotherapy drug)-induced damage in pig kidney (LLC-PK1) cells. It focused on assessing the role of mitogen-activated protein kinases as important mechanistic elements in kidney protection.

Results

The reduced cell viability induced by cisplatin was significantly recovered with FBG extract and ginsenoside 20(S)-Rg3 dose-dependently. The cisplatin-induced elevated protein levels of phosphorylated c-Jun N-terminal kinase (JNK), p53, and cleaved caspase-3 were decreased after cotreatment with FBG extract or ginsenoside 20(S)-Rg3. The elevated percentage of apoptotic LLC-PK1 cells induced by cisplatin treatment was significantly abrogated by cotreatment with FBG and the ginsenoside 20(S)-Rg3.

Conclusion

FBG and its major ginsenoside 20(S)-Rg3, ameliorated cisplatin-induced nephrotoxicity in LLC-PK1 cells by blocking the JNK–p53–caspase-3 signaling cascade.

Depletion of B cell CLL/Lymphoma 11B Gene Expression Represses Glioma Cell Growth

B cell CLL/lymphoma 11B (Bcl11b), a C2H2 zinc finger transcription factor, not only serves as a critical regulator in development but also plays the controversial role in T cell acute lymphoblastic leukemia (T-ALL). We previously found that the enriched expression of Bcl11b was detected in high tumorigenic C6 glioma cells. However, the role of Bcl11b in glioma malignancy and its mechanisms remains to be uncovered. In this study, using the lentivirus-mediated knockdown (KD) approach, we found that Bcl11b KD in tumorigenic C6 cells reduced the cell proliferation, colony formation, and migratory ability. The results were further verified using two human malignant glioma cell lines, U87 and U251 cells. A cyclin-dependent kinase inhibitor p21, a known Bcl11b target, was significantly upregulated in tumorigenic C6, U87, and U251 cells after Bcl11b KD. Cellular senescence was observed by examination of the β-galactosidase activity in U87 and U251 cells with Bcl11b KD. Reduced expression of stemness gene Sox-2 and its downstream effector Bmi-1 was also observed in U87 and U251 cells with Bcl11b KD. These results suggest that the ablation of Bcl11b gene expression induced glioma cell senescence. Propidium iodide (PI) staining combined with flow cytometry analysis also showed that Bcl11b KD led to the cell cycle arrest of U87 and U251 cells at the G0/G1 or at the S phase, indicating that Bcl11b is required for glioma cell cycle progression. Together, this is the first study to show that the inhibition of Bcl11b suppresses glioma cell growth by regulating the expression of the cell cycle regulator p21 and stemness-associated genes (Sox-2/Bmi-1).

Long-term arsenite exposure induces premature senescence in B cell lymphoma A20 cells

Chronic arsenite exposure induces immunosuppression, but the precise mechanisms remain elusive. Our previous studies demonstrated that arsenite exposure for 24 h induces G0/G1 arrest in mouse B lymphoma A20 cells and the arrest is caused through induction of cyclin-dependent kinase inhibitor p16(INK4a) followed by accumulation of an Rb family protein, p130. In this study, we further investigated the consequences of long-term arsenite exposure of A20 cells. The results demonstrated that exposure to 10 μM sodium arsenite up to 14 days induces a great increase in G0/G1 arrest, irreversible cell growth suppression, cellular morphological changes and positive staining for senescence-associated β-galactosidase. The long-term arsenite exposure also induced up-regulation of p16(INK4a) followed by robust accumulation of p130 and activation of the p53 pathway. Knockdown experiments with siRNA showed that p130 accumulation is essential for cell cycle arrest by long-term arsenite exposure. Since p16(INK4a) and the p53 pathway are known to be activated by DNA damage, we investigated the involvement of DNA damage formation by long-term arsenite exposure. We found that a variety of DNA repair-related genes were significantly down-regulated from 24 h of arsenite exposure and activation-induced cytidine deaminase was greatly up-regulated after long-term arsenite exposure. Consistent with these findings, long-term arsenite exposure increased a DNA double-strand break marker, γ-H2AX and increased mutation frequency in a Bcl6 gene region. These results revealed that long-term arsenite exposure induces premature senescence through DNA damage increase and p130 accumulation in lymphoid cells.