Zhi Xu He

Plumbagin induces apoptotic and autophagic cell death through inhibition of the PI3K/Akt/mTOR pathway in human non-small cell lung cancer cells

Plumbagin (PLB) has shown anti-cancer activity but the mechanism is unclear. This study has found that PLB has a potent pro-apoptotic and pro-autophagic effect on A549 and H23 cells. PLB arrests cells in G2/M phase, and increases the intracellular level of reactive oxygen species in both cell lines. PLB dose-dependently induces autophagy through inhibition of PI3K/Akt/mTOR pathway as indicated by reduced phosphorylation of Akt and mTOR. Inhibition or induction of autophagy enhances PLB-induced apoptosis. There is crosstalk between PLB-induced apoptosis and autophagy. These findings indicate that PLB initiates both apoptosis and autophagy in NSCLC cells through coordinated pathways.

Graphene quantum dots induce apoptosis, autophagy, and inflammatory response via p38 mitogen-activated protein kinase and nuclear factor-κB mediated signaling pathways in activated THP-1 macrophages

The biomedical application of graphene quantum dots (GQDs) is a new emerging area. However, their safety data are still in scarcity to date. Particularly, the effect of GQDs on the immune system remains unknown. This study aimed to elucidate the interaction of GQDs with macrophages and the underlying mechanisms. Our results showed that GQDs slightly affected the cell viability and membrane integrity of macrophages, whereas GQDs significantly increased reactive oxygen species (ROS) generation and apoptotic and autophagic cell death with an increase in the expression level of Bax, Bad, caspase 3, caspase 9, beclin 1, and LC3-I/II and a decrease in that of Bcl-2. Furthermore, low concentrations of GQDs significantly increased the expression of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-8, whereas high concentrations of GQDs elicited opposite effects on the cytokines production. SB202190, a selective inhibitor of p38 mitogen-activated protein kinase (MAPK), abolished the cytokine-inducing effect of GQDs in macrophages. Moreover, GQDs significantly increased the phosphorylation of p38 MAPK and p65, and promoted the nuclear translocation of nuclear factor-κB (NF-κB). Taken together, these results show that GQDs induce ROS generation, apoptosis, autophagy, and inflammatory response via p38MAPK and NF-κB mediated signaling pathways in THP-1 activated macrophages.

The investigational Aurora kinase A inhibitor alisertib (MLN8237) induces cell cycle G2/M arrest, apoptosis, and autophagy via p38 MAPK and Akt/mTOR signaling pathways in human breast cancer cells

Alisertib (ALS) is an investigational potent Aurora A kinase inhibitor currently undergoing clinical trials for the treatment of hematological and non-hematological malignancies. However, its antitumor activity has not been tested in human breast cancer. This study aimed to investigate the effect of ALS on the growth, apoptosis, and autophagy, and the underlying mechanisms in human breast cancer MCF7 and MDA-MB-231 cells. In the current study, we identified that ALS had potent growth-inhibitory, pro-apoptotic, and pro-autophagic effects in MCF7 and MDA-MB-231 cells. ALS arrested the cells in G2/M phase in MCF7 and MDA-MB-231 cells which was accompanied by the downregulation of cyclin-dependent kinase (CDK)1/cell division cycle (CDC) 2, CDK2, and cyclin B1 and upregulation of p21 Waf1/Cip1, p27 Kip1, and p53, suggesting that ALS induces G2/M arrest through modulation of p53/p21/CDC2/cyclin B1 pathways. ALS induced mitochondria-mediated apoptosis in MCF7 and MDA-MB-231 cells; ALS significantly decreased the expression of B-cell lymphoma 2 (Bcl-2), but increased the expression of B-cell lymphoma 2-associated X protein (Bax) and p53-upregulated modulator of apoptosis (PUMA), and increased the expression of cleaved caspases 3 and 9. ALS significantly increased the expression level of membrane-bound microtubule-associated protein 1 light chain 3 (LC3)-II and beclin 1 and induced inhibition of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) and p38 mitogen-activated protein kinase (MAPK) pathways in MCF7 and MDA-MB-231 cells as indicated by their altered phosphorylation, contributing to the pro-autophagic activities of ALS. Furthermore, treatment with wortmannin markedly downregulated ALS-induced p38 MAPK activation and LC3 conversion. In addition, knockdown of the p38 MAPK gene by ribonucleic acid interference upregulated Akt activation and resulted in LC3-II accumulation. These findings indicate that ALS promotes cellular apoptosis and autophagy in breast cancer cells via modulation of p38 MAPK/Akt/mTOR pathways. Further studies are warranted to further explore the molecular targets of ALS in the treatment of breast cancer.

Induction of apoptosis and autophagy via sirtuin1- and PI3K/Akt/mTOR-mediated pathways by plumbagin in human prostate cancer cells.

Plumbagin (PLB) has been shown to have anticancer activities in animal models, but the role of PLB in prostate cancer treatment is unclear. This study aimed to investigate the effects of PLB on apoptosis and autophagy and the underlying mechanisms in human prostate cancer cell lines PC-3 and DU145. Our study has shown that PLB had potent pro-apoptotic and pro-autophagic effects on PC-3 and DU145 cells. PLB induced mitochondria-mediated apoptosis and autophagy in concentration- and time-dependent manners in both PC-3 and DU145 cells. PLB induced inhibition of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) and p38 mitogen-activated protein kinase (MAPK) pathways and activation of 5′-AMP-dependent kinase (AMPK) as indicated by their altered phosphorylation, contributing to the pro-autophagic activity of PLB. Modulation of autophagy altered basal and PLB-induced apoptosis in both cell lines. Furthermore, PLB downregulated sirtuin 1 (Sirt1), and inhibition of Sirt1 enhanced autophagy, whereas the induction of Sirt1 abolished PLB-induced autophagy in PC-3 and DU145 cells. In addition, PLB downregulated pre-B cell colony-enhancing factor/visfatin, and the inhibition of pre-B cell colony-enhancing factor/visfatin significantly enhanced basal and PLB-induced apoptosis and autophagy in both cell lines. Moreover, reduction of intracellular reactive oxygen species (ROS) level attenuated the apoptosis- and autophagy-inducing effects of PLB on both PC-3 and DU145 cells. These findings indicate that PLB promotes apoptosis and autophagy in prostate cancer cells via Sirt1- and PI3K/Akt/mTOR-mediated pathways with contribution from AMPK-, p38 MAPK-, visfatin-, and ROS-associated pathways.

Pro-apoptotic and pro-autophagic effects of the Aurora kinase A inhibitor alisertib (MLN8237) on human osteosarcoma U-2 OS and MG-63 cells through the activation of mitochondria-mediated pathway and inhibition of p38 MAPK/PI3K/Akt/mTOR signaling pathway.

Osteosarcoma (OS) is the most common malignant bone tumor occurring mostly in children and adolescents between 10 and 20 years of age with poor response to current therapeutics. Alisertib (ALS, MLN8237) is a selective Aurora kinase A inhibitor that displays anticancer effects on several types of cancer. However, the role of ALS in the treatment of OS remains unknown. This study aimed to investigate the effects of ALS on the cell growth, apoptosis, autophagy, and epithelial to mesenchymal transition (EMT) and the underlying mechanisms in two human OS cell lines U-2 OS and MG-63. The results showed that ALS had potent growth inhibitory, pro-apoptotic, pro-autophagic, and EMT inhibitory effects on U-2 OS and MG-63 cells. ALS remarkably induced G2/M arrest and down-regulated the expression levels of cyclin-dependent kinases 1 and 2 and cyclin B1 in both U-2 OS and MG-63 cells. ALS markedly induced mitochondria-mediated apoptosis with a significant increase in the expression of key pro-apoptotic proteins and a decrease in main anti-apoptotic proteins. Furthermore, ALS promoted autophagic cell death via the inhibition of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) and p38 mitogen-activated protein kinase (p38 MAPK) signaling pathways, and activation of 5′-AMP-dependent kinase (AMPK) signaling pathway. Inducers or inhibitors of apoptosis or autophagy simultaneously altered ALS-induced apoptotic and autophagic death in both U-2 OS and MG-63 cells, suggesting a crosstalk between these two primary modes of programmed cell death. Moreover, ALS suppressed EMT-like phenotypes with a marked increase in the expression of E-cadherin but a decrease in N-cadherin in U-2 OS and MG-63 cells. ALS treatment also induced reactive oxygen species (ROS) generation but inhibited the expression levels of sirtuin 1 and nuclear factor-erythroid-2-related factor 2 (Nrf2) in both cell lines. Taken together, these findings show that ALS promotes apoptosis and autophagy but inhibits EMT via PI3K/Akt/mTOR, p38 MAPK, and AMPK signaling pathways with involvement of ROS- and sirtuin 1-associated pathways in U-2 OS and MG-63 cells. ALS is a promising anticancer agent in OS treatment and further studies are needed to confirm its efficacy and safety in OS chemotherapy.

Clinical pharmacology of dipeptidyl peptidase 4 inhibitors indicated for the treatment of type 2 diabetes mellitus.

Dipeptidyl peptidase‐4 (DPP‐4) inhibitors are a class of oral antidiabetic drugs that improve glycaemic control without causing weight gain or increasing hypoglycaemic risk in patients with type 2 diabetes mellitus (T2DM). The eight available DPP‐4 inhibitors, including alogliptin, anagliptin, gemigliptin, linagliptin, saxagliptin, sitagliptin, teneligliptin, and vildagliptin, are small molecules used orally with identical mechanism of action and similar safety profiles in patients with T2DM. DPP‐4 inhibitors may be used as monotherapy or in double or triple combination with other oral glucose‐lowering agents such as metformin, thiazolidinediones, or sulfonylureas. Although DPP‐4 inhibitors have the same mode of action, they differ by some important pharmacokinetic and pharmacodynamic properties that may be clinically relevant in some patients. The main differences between the eight gliptins include: potency, target selectivity, oral bioavailability, elimination half‐life, binding to plasma proteins, metabolic pathways, formation of active metabolite(s), main excretion routes, dosage adjustment for renal and liver insufficiency, and potential drug‐drug interactions. The off‐target inhibition of selective DPP‐4 inhibitors is responsible for multiorgan toxicities such as immune dysfunction, impaired healing, and skin reactions. As a drug class, the DPP‐4 inhibitors have become accepted in clinical practice due to their excellent tolerability profile, with a low risk of hypoglycaemia, a neutral effect on body weight, and once‐daily dosing. It is unknown if DPP‐4 inhibitors can prevent disease progression. More clinical studies are needed to validate the optimal regimens of DPP‐4 inhibitors for the management of T2DM when their potential toxicities are closely monitored.

Plumbagin induces cell cycle arrest and autophagy and suppresses epithelial to mesenchymal transition involving PI3K/Akt/mTOR-mediated pathway in human pancreatic cancer cells

Plumbagin (PLB), an active naphthoquinone compound, has shown potent anticancer effects in preclinical studies; however, the effect and underlying mechanism of PLB for the treatment of pancreatic cancer is unclear. This study aimed to examine the pancreatic cancer cell killing effect of PLB and investigate the underlying mechanism in human pancreatic cancer PANC-1 and BxPC-3 cells. The results showed that PLB exhibited potent inducing effects on cell cycle arrest in PANC-1 and BxPC-3 cells via the modulation of cell cycle regulators including CDK1/CDC2, cyclin B1, cyclin D1, p21 Waf1/Cip1, p27 Kip1, and p53. PLB treatment concentration- and time-dependently increased the percentage of autophagic cells and significantly increased the expression level of phosphatase and tensin homolog, beclin 1, and the ratio of LC3-II over LC3-I in both PANC-1 and BxPC-3 cells. PLB induced inhibition of phosphatidylinositol 3-kinase (PI3K)/protein kinase B/mammalian target of rapamycin and p38 mitogen-activated protein kinase (p38 MAPK) pathways and activation of 5′-AMP-dependent kinase as indicated by their altered phosphorylation, contributing to the proautophagic activities of PLB in both cell lines. Furthermore, SB202190, a selective inhibitor of p38 MAPK, and wortmannin, a potent, irreversible, and selective PI3K inhibitor, remarkably enhanced PLB-induced autophagy in PANC-1 and BxPC-3 cells, indicating the roles of PI3K and p38 MAPK mediated signaling pathways in PLB-induced autophagic cell death in both cell lines. In addition, PLB significantly inhibited epithelial to mesenchymal transition phenotype in both cell lines with an increase in the expression level of E-cadherin and a decrease in N-cadherin. Moreover, PLB treatment significantly suppressed the expression of Sirt1 in both cell lines. These findings show that PLB promotes cell cycle arrest and autophagy but inhibits epithelial to mesenchymal transition phenotype in pancreatic cancer cells with the involvement of PI3K/protein kinase B/mammalian target of rapamycin and p38 MAPK mediated pathways.

Alisertib induces cell cycle arrest and autophagy and suppresses epithelial-to-mesenchymal transition involving PI3K/Akt/mTOR and sirtuin 1-mediated signaling pathways in human pancreatic cancer cells

Pancreatic cancer is the most aggressive cancer worldwide with poor response to current therapeutics. Alisertib (ALS), a potent and selective Aurora kinase A inhibitor, exhibits potent anticancer effects in preclinical and clinical studies; however, the effect and underlying mechanism of ALS in the pancreatic cancer treatment remain elusive. This study aimed to examine the effects of ALS on cell growth, autophagy, and epithelial-to-mesenchymal transition (EMT) and to delineate the possible molecular mechanisms in human pancreatic cancer PANC-1 and BxPC-3 cells. The results showed that ALS exerted potent cell growth inhibitory, pro-autophagic, and EMT-suppressing effects in PANC-1 and BxPC-3 cells. ALS remarkably arrested PANC-1 and BxPC-3 cells in G2/M phase via regulating the expression of cyclin-dependent kinases 1 and 2, cyclin B1, cyclin D1, p21 Waf1/Cip1, p27 Kip1, and p53. ALS concentration-dependently induced autophagy in PANC-1 and BxPC-3 cells, which may be attributed to the inhibition of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR), p38 mitogen-activated protein kinase (p38 MAPK), and extracellular signal-regulated kinases 1 and 2 (Erk1/2) but activation of 5′-AMP-dependent kinase signaling pathways. ALS significantly inhibited EMT in PANC-1 and BxPC-3 cells with an increase in the expression of E-cadherin and a decrease in N-cadherin. In addition, ALS suppressed the expression of sirtuin 1 (Sirt1) and pre-B cell colony-enhancing factor/visfatin in both cell lines with a rise in the level of acetylated p53. These findings show that ALS induces cell cycle arrest and promotes autophagic cell death but inhibits EMT in pancreatic cancer cells with the involvement of PI3K/Akt/mTOR, p38 MAPK, Erk1/2, and Sirt1-mediated signaling pathways. Taken together, ALS may represent a promising anticancer drug for pancreatic cancer treatment. More studies are warranted to investigate other molecular targets and mechanisms and verify the efficacy and safety of ALS in the treatment of pancreatic cancer.

Alisertib, an Aurora kinase A inhibitor, induces apoptosis and autophagy but inhibits epithelial to mesenchymal transition in human epithelial ovarian cancer cells

Ovarian cancer is a leading killer of women, and no cure for advanced ovarian cancer is available. Alisertib (ALS), a selective Aurora kinase A (AURKA) inhibitor, has shown potent anticancer effects, and is under clinical investigation for the treatment of advanced solid tumor and hematologic malignancies. However, the role of ALS in the treatment of ovarian cancer remains unclear. This study investigated the effects of ALS on cell growth, apoptosis, autophagy, and epithelial to mesenchymal transition (EMT), and the underlying mechanisms in human epithelial ovarian cancer SKOV3 and OVCAR4 cells. Our docking study showed that ALS, MLN8054, and VX-680 preferentially bound to AURKA over AURKB via hydrogen bond formation, charge interaction, and π-π stacking. ALS had potent growth-inhibitory, proapoptotic, proautophagic, and EMT-inhibitory effects on SKOV3 and OVCAR4 cells. ALS arrested SKOV3 and OVCAR4 cells in G2/M phase and induced mitochondria-mediated apoptosis and autophagy in both SKOV3 and OVCAR4 cell lines in a concentration-dependent manner. ALS suppressed phosphatidylinositol 3-kinase/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) and p38 mitogen-activated protein kinase pathways but activated 5′-AMP-dependent kinase, as indicated by their altered phosphorylation, contributing to the proautophagic activity of ALS. Modulation of autophagy altered basal and ALS-induced apoptosis in SKOV3 and OVCAR4 cells. Further, ALS suppressed the EMT-like phenotype in both cell lines by restoring the balance between E-cadherin and N-cadherin. ALS downregulated sirtuin 1 and pre-B cell colony enhancing factor (PBEF/visfatin) expression levels and inhibited phosphorylation of AURKA in both cell lines. These findings indicate that ALS blocks the cell cycle by G2/M phase arrest and promotes cellular apoptosis and autophagy, but inhibits EMT via phosphatidylinositol 3-kinase/Akt/mTOR-mediated and sirtuin 1-mediated pathways in human epithelial ovarian cancer cells. Further studies are warranted to validate the efficacy and safety of ALS in the treatment of ovarian cancer.

Targeting Na+/K+‐translocating adenosine triphosphatase in cancer treatment

The Na+/K+‐translocating adenosine triphosphatase (ATPase) transports sodium and potassium across the plasma membrane and represents a potential target in cancer chemotherapy. Na+/K+‐ATPase belongs to the P‐type ATPase family (also known as E1–E2 ATPase), which is involved in transporting certain ions, metals, and lipids across the plasma membrane of mammalian cells. In humans, the Na+/K+‐ATPase is a binary complex of an α‐subunit that has four isoforms (α1–α4) and a β‐subunit that has three isoforms (β1–β3). This review aims to update our knowledge on the role of Na+/K+‐ATPase in cancer development and metastasis, as well as on how Na+/K+‐ATPase inhibitors kill tumour cells. The Na+/K+‐ATPase has been found to be associated with cancer initiation, growth, development, and metastasis. Cardiac glycosides have exhibited anticancer effects in cell‐based and mouse studies via inhibition of the Na+/K+‐ATPase and other mechanisms. Na+/K+‐ATPase inhibitors may kill cancer cells via induction of apoptosis and autophagy, radical oxygen species production, and cell cycle arrest. They also modulate multiple signalling pathways that regulate cancer cell survival and death, which contributes to their antiproliferative activities in cancer cells. The clinical evidence supporting the use of Na+/K+‐ATPase inhibitors as anticancer drugs is weak. Several phase I and phase II clinical trials with digoxin, Anvirzel, and huachansu (an intravenous formulated extract of the venom of the wild toad), either alone or more often in combination with other anticancer agents, have shown acceptable safety profiles but limited efficacy in cancer patients. Well‐designed randomized clinical trials with reasonable sample sizes are certainly warranted to confirm the efficacy and safety of cardiac glycosides for the treatment of cancer.