Involvement of oxidative stress in taxol-induced apoptosis in chronic myelogenous leukemia K562 cells

Deciphering the cytotoxic potential of acamprosate and acamprosate loaded mesoporous silica nanoparticles in hepatocellular carcinoma: an in vitro and in silico approach

Hepatocellular carcinoma (HCC) is a healthcare concern that causes most cancer-linked deaths around the world. This work was aimed at unraveling the anticancer potential of acamprosate and development of mesoporous silica nanoparticle (MSN) drug delivery system to increase the therapeutic efficacy of acamprosate. For this purpose, the MSNs were synthesized and encapsulated with acamprosate (MSN-Acamp). The MSN and MSN-Acamp were characterized by DLS, Zeta potential, UV spectroscopy, SEM, FTIR, XRD, DFT, and XPS. Biological effects were evaluated by MTT and lactate dehydrogenase assays. The apoptotic mode of cell death was evaluated by fluorescence imaging and DNA fragmentation assay. Cell cycle assessment and Annexin V-FITC/PI staining were performed to depict the phase of cell arrest and stage of apoptotic cells respectively. The acamprosate was found to exhibit cytotoxic effect and MSN-Acamp exhibited an increased cytotoxicity. Apoptotic mode of cell death was revealed by fluorescence imaging as nuclear fragmentation, production of reactive oxygen species (ROS), loss of membrane potential in mitochondria, and chromatin condensation/fragmentation were found. The docking results revealed that acamprosate had a considerable binding affinity with Bcl-2, Mcl-1, EGFR, and mTOR proteins. Overall, our results indicated that acamprosate and MSN-Acamp had a potent apoptotic effect and MSNs are propitious drug carriers to increase therapeutic effect in HCC.

Paclitaxel mediates the PI3K/AKT/mTOR pathway to reduce proliferation of FLT3‑ITD+ AML cells and promote apoptosis

Acute myeloid leukemia (AML) with internal tandem duplication (ITD) mutations in the FLT3 tyrosine kinase tend to have a poor prognosis. FLT3-ITD can promote the progress of AML by activating the PI3K/AKT/mTOR pathway. Paclitaxel (PTX) is a natural anticancer drug that has been widely used in chemotherapy for multiple malignancies. The present study used the CCK-8 assay, flow cytometry, PCR and western blotting to explore the anti-leukemia effect and possible mechanisms of PTX on MV4-11 cells with the FLT3-ITD mutation and the underlying mechanism. As a result, it was found that PTX could inhibit proliferation of MV4-11 cells and promoted apoptosis by inhibiting the PI3K/AKT/mTOR pathway.

Effect of vitamin E on doxorubicin and paclitaxel-induced memory impairments in male rats

PURPOSE

In addition to peripheral neuronal dysfunction, conventional chemotherapy can be associated with other neurological treatment-limiting adverse effects, including cognitive dysfunction, memory impairment, and anxiety, which are referred to as "chemobrain". This study aimed to investigate the effects of doxorubicin (DOX) and paclitaxel (PAC) on learning and memory in rats using radial arm water maze (RAWM) and investigated a potential beneficial effect of vitamin E (Vit. E).

METHODS

Adult male rats were injected with four doses of 2 mg/kg/week DOX, or 2 mg/kg PAC every other day intraperitoneally. Vit. E was co-administered with these drugs in other groups to study its antioxidative effects. Using the RAWM, each rat was assessed for learning and memory performance through two sets of six trials separated by a 5-min rest period evaluating both short- and long-term effects on memory.

RESULTS

There was no deficit in learning or long-term memory in both drug groups compared to control. However, rats in both drug groups made significantly more errors in all short-term memory trials. This effect was mitigated when Vit. E was co-administered with either drug. Moreover, PAC (but not DOX) induced hippocampal lipid peroxidation by increasing the levels of standard biomarker thiobarbituric acid reactive substances (TBARS). Interestingly, Vit. E prevented PAC-induced hippocampal oxidative stress. Furthermore, both DOX and PAC were correlated with reduction in Brain-Derived Neurotrophic Factor (BDNF) expression levels in the hippocampus, which was overcome by the co-administration of Vit. E.

CONCLUSION

There is a potential role of Vit. E in alleviating short-term memory impairment in rats exposed to chemotherapy, possibly by reducing hippocampal oxidative stress and neurodegeneration.

Cellular Efficacy of Fattigated Nanoparticles and Real-Time ROS Occurrence Using Microfluidic Hepatocarcinoma Chip System: Effect of Anticancer Drug Solubility and Shear Stress

The objective of this study was to evaluate the effectiveness of organ-on-chip system investigating simultaneous cellular efficacy and real-time reactive oxygen species (ROS) occurrence of anticancer drug-loaded nanoparticles (NPs) using hepatocarcinoma cells (HepG2) chip system under static and hepatomimicking shear stress conditions (5 dyne/cm2). Then, the role of hepatomimetic shear stress exposed to HepG2 and drug solubility were compared. The highly soluble doxorubicin (DOX) and poorly soluble paclitaxel (PTX) were chosen. Fattigated NPs (AONs) were formed via self-assembly of amphiphilic albumin (HSA)-oleic acid conjugate (AOC). Then, drug-loaded AONs (DOX-AON or PTX-AON) were exposed to a serum-free HepG2 medium at 37 °C and 5% carbon dioxide for 24 h using a real-time ROS sensor chip-based microfluidic system. The cellular efficacy and simultaneous ROS occurrence of free drugs and drug-loaded AONs were compared. The cellular efficacy of drug-loaded AONs varied in a dose-dependent manner and were consistently correlated with real-time of ROS occurrence. Drug-loaded AONs increased the intracellular fluorescence intensity and decreased the cellular efficacy compared to free drugs under dynamic conditions. The half-maximal inhibitory concentration (IC50) values of free DOX (13.4 μg/mL) and PTX (54.44 μg/mL) under static conditions decreased to 11.79 and 38.43 μg/mL, respectively, under dynamic conditions. Furthermore, DOX- and PTX-AONs showed highly decreased IC50 values of 5.613 and 21.86 μg/mL, respectively, as compared to free drugs under dynamic conditions. It was evident that cellular efficacy and real-time ROS occurrence were well-correlated and highly dependent on the drug-loaded nanostructure, drug solubility and physiological shear stress.

Naringin and naringenin counteract taxol-induced liver injury in Wistar rats via suppression of oxidative stress, apoptosis and inflammation

This research aimed to evaluate the preventing effects of naringin, naringenin, and their combination on liver injury induced by Taxol (paclitaxel) in Wistar rats. Male Wistar rats received 2 mg/kg Taxol intraperitoneal injections twice weekly on the second and fifth days of each week for 6 weeks. During the same period as Taxol administration, rats were given naringin, naringenin, or a combination of the two (10 mg/kg b.wt) every other day. Treatment with naringin and/or naringenin reduced the abnormally high serum levels of total bilirubin, aspartate transaminase, alanine transaminase, alkaline phosphatase, lactate dehydrogenase, and gamma-glutamyl transferase in Taxol-treated rats. It also significantly increased the level of serum albumin, indicating an improvement in the liver. The perturbed histological liver changes were markedly improved due to the naringin and/or naringenin treatment in Taxol-administered rats. Additionally, the treatments reduced high hepatic lipid peroxidation and increased liver glutathione content as well as the activities of superoxide dismutase and glutathione peroxidase. Furthermore, the treatments reduced the levels of alpha-fetoprotein and caspase-3, a pro-apoptotic mediator. The naringin and naringenin mixture appeared more effective in improving organ function and structural integrity. In conclusion, naringin and naringenin are suggested to employ their hepatoprotective benefits via boosting the body's antioxidant defense system, reducing inflammation, and suppressing apoptosis.

PARP deficiency causes hypersensitivity to Taxol through oxidative stress induced DNA damage

Taxol is an antitumor drug derived from the bark of the Pacific Yew tree that inhibits microtubule disassembly, resulting in cell cycle arrest in late G2 and M phases. Additionally, Taxol increases cellular oxidative stress by generating reactive oxygen species. We hypothesized that the inhibition of specific DNA repair machinery/mechanisms would increase cellular sensitivity to the oxidative stress capacity of Taxol. Initial screening using Chinese hamster ovary (CHO) cell lines demonstrated that base excision repair deficiency, especially PARP deficiency, caused cellular Taxol hypersensitivity. Taxane diterpenes-containing Taxus yunnanensis extract also showed hypertoxicity in PARP deficient cells, which was consistent with other microtubule inhibitors like colcemid, vinblastine, and vincristine. Acute exposure of 50 nM Taxol treatment induced both significant cytotoxicity and M-phase arrest in PARP deficient cells, but caused neither significant cytotoxicity nor late G2-M cell cycle arrest in wild type cells. Acute exposure of 50 nM Taxol treatment induced oxidative stress and DNA damage. The antioxidant Ascorbic acid 2 glucoside partially reduced the cytotoxicity of Taxol in PARP deficient cell lines. Finally, the PARP inhibitor Olaparib increased cytotoxicity of Taxol in wild type CHO cells and two human cancer cell lines. Our study clearly demonstrates that cytotoxicity of Taxol would be enhanced by inhibiting PARP function as an enzyme implicated in DNA repair for oxidative stress.

Self-transfecting GMO-PMO chimera targeting Nanog enable gene silencing in vitro and suppresses tumor growth in 4T1 allografts in mouse

Phosphorodiamidate morpholino oligonucleotide (PMO)-based antisense reagents cannot enter cells without the help of a delivery technique, which limits their clinical applications. To overcome this problem, self-transfecting guanidinium-linked morpholino (GMO)-PMO or PMO-GMO chimeras have been explored as antisense agents. GMO facilitates cellular internalization and participates in Watson-Crick base pairing. Targeting NANOG in MCF7 cells resulted in decline of the whole epithelial to mesenchymal transition (EMT) and stemness pathway, evident through its phenotypic manifestations, all of which were promulgated in combination with Taxol due to downregulation of MDR1 and ABCG2. GMO-PMO-mediated knockdown of no tail gene resulted in desired phenotypes in zebrafish even upon delivery after 16-cell stages. In BALB/c mice, 4T1 allografts were found to regress via intra-tumoral administration of NANOG GMO-PMO antisense oligonucleotides (ASOs), which was associated with occurrence of necrotic regions. GMO-PMO-mediated tumor regression restored histopathological damage in liver, kidney, and spleen caused by 4T1 mammary carcinoma. Serum parameters of systemic toxicity indicated that GMO-PMO chimeras are safe. To the best of our knowledge, self-transfecting antisense reagent is the first report since the discovery of guanidinium-linked DNA (DNG), which could be useful as a combination cancer therapy and, in principle, can render inhibition of any target gene without using any delivery vehicle.

Hsp90 protected chicken primary myocardial cells from heat-stress injury by inhibiting oxidative stress and calcium overload in mitochondria

Severe heat stress can cause human and animal heart failure and sudden death, which is an important issue of public health worldwide. Our previous studies in animals showed that myocardial cells injury was critical in the above process, and Hsp90 induction has a definite anti-myocardial injury effect, especially through aspirin (ASA). But the mechanism has not been fully clarified. In this study, an in vitro heat stress model of chicken primary myocardial cells (CPMCs) most sensitive to heat stress was used to explore the cell injuries and corresponding molecular resistance mechanism. We found that heat stress resulted in serious oxidation stress and calcium overload in mitochondria, which destroyed the mitochondrial structure and function and then triggered the cell death mechanism of CPMCs. Hsp90 was proven to be a central regulator for resisting heat-stress injury in CPMCs mitochondria using its inhibitor and inducer (geldanamycin and ASA), respectively. The mechanism involved that Hsp90 could activate Akt and PKM2 signals to promote Bcl-2 translocation into mitochondria and its phosphorylation, thereby preventing ROS production and subsequent cell apoptosis. In addition, Hsp90 inhibited mitochondrial calcium overload to overcome MPTP opening and MMP suppression through the inhibitory effect of Raf-1-ERK activation on the CREB-IP3R pathway. This study is the first to reveal a pivotal reason for heat-stressed damage in chicken myocardial cells at subcellular level and identify an effective regulator, Hsp90, and its protective mechanisms responsible for maintaining mitochondrial homeostasis.

Soluble epoxide hydrolase inhibition alleviates chemotherapy induced neuropathic pain

Chemotherapy induced peripheral neuropathy (CIPN) is a particularly pernicious form of neuropathy and the associated pain is the primary dose-limiting factor of life-prolonging chemotherapy treatment. The prevalence of CIPN is high and can last long after treatment has been stopped. Currently, late in the COVID-19 pandemic, there are still increased psychological pressures on cancer patients as well as additional challenges in providing analgesia for them. These include the risks of nonsteroidal anti-inflammatory drug (NSAID) analgesics potentially masking early infection symptoms and the immunosuppression of steroidal and opiate based approaches. Even without these concerns, CIPN is often inadequately treated with few therapies that offer significant pain relief. The experiments we report use soluble epoxide hydrolase inhibitors (sEHI) which relieved this intractable pain in preclinical models. Doses of EC5026, an IND candidate intended to treat neuropathic pain, elicited dose dependent analgesic responses in multiple models including platinum-based, taxane, and vinca alkaloid-based CIPN pain in Sprague Dawley rats. At the same time as a class, the sEHI are known to result in fewer debilitating side effects of other analgesics, likely due to their novel mechanism of action. Overall, the observed dose-dependent analgesia in both male and female rats across multiple models of chemotherapy induced neuropathic pain holds promise as a useful tool when translated to the clinic.

Chalcone-Acridine Hybrid Suppresses Melanoma Cell Progression via G2/M Cell Cycle Arrest, DNA Damage, Apoptosis, and Modulation of MAP Kinases Activity

This study was focused on investigating the antiproliferative effects of chalcone hybrids in melanoma cancer cells. Among seven chalcone hybrids, the chalcone-acridine hybrid 1C was the most potent and was selected for further antiproliferative mechanism studies. This in vitro study revealed the potent antiproliferative effect of 1C via cell cycle arrest and apoptosis induction. Cell cycle arrest at the G2/M phase was associated with modulation of expression or phosphorylation of specific cell cycle-associated proteins (cyclin B1, p21, and ChK1), tubulins, as well as with the activation of the DNA damage response pathway. Chalcone 1C also induced apoptosis accompanied by mitochondrial dysfunction evidenced by a decrease in mitochondrial membrane potential, increase in Bax/Bcl-xL ratio and cytochrome c release followed by caspase 3/7 activation. In addition, increased phosphorylation of MAP kinases (Erk1/2, p38 and JNK) was observed in chalcone 1C-treated melanoma cells. The strong antiproliferative activities of this chalcone-acridine hybrid suggest that it may be useful as an antimelanoma agent in humans.

The Preventive Effects of Naringin and Naringenin against Paclitaxel-Induced Nephrotoxicity and Cardiotoxicity in Male Wistar Rats

This study assessed the preventive properties of naringin and naringenin on paclitaxel-induced nephrotoxicity and cardiotoxicity in adult male Wistar rats. Intraperitoneal injection of paclitaxel 2 mg/kg body weight, two days/week on the 2nd and 5th days of each week, with or without oral administration of naringin and/or naringenin 10 mg/kg body weight every other day, was continued for six weeks. Treatment of rats with naringin and/or naringenin significantly reversed elevated serum creatinine, urea, and uric acid levels caused by paclitaxel, reflecting improved kidney function. Similarly, heart dysfunction induced by paclitaxel was alleviated after treatment with naringin and/or naringenin, as evidenced by significant decreases in elevated CK-MB and LDH activities. After drug administration, histopathological findings and lesion scores in the kidneys and heart were markedly decreased by naringin and/or naringenin. Moreover, the treatments reversed renal and cardiac lipid peroxidation and the negative impacts on antioxidant defenses via raising GSH, SOD, and GPx. The preventive effects of naringin and naringenin were associated with suppressing oxidative stress and reestablishing antioxidant defenses. A combination of naringin and naringenin was the most efficacious in rescuing organ function and structure.

Hedgehog Suppresses Paclitaxel Sensitivity by Regulating Akt-Mediated Phosphorylation of Bax in EGFR Wild-Type Non-Small Cell Lung Cancer Cells

Non-small cell lung cancer (NSCLC) is one of the most common and deadly cancers worldwide. Among NSCLC patients, almost half have wild-type epidermal growth factor receptor (EGFR WT). The primary therapeutic option for these EGFR WT NSCLC patients is chemotherapy, while NSCLC patients with EGFR mutations have more diverse therapeutic options, including EGFR tyrosine kinase inhibitors. Moreover, NSCLC patients with EGFR WT have worse chemotherapy response than EGFR mutant NSCLC patients. Thus, an urgent need exists for novel therapeutic strategies to improve chemotherapy response in EGFR WT NSCLC patients. Hedgehog signaling is known to be highly active in NSCLC; however, its potential role in chemoresistance is not fully understood. In the present study, we found that paclitaxel (PTX) treatment induces hedgehog signaling in EGFR WT NSCLC cells, and inhibition of hedgehog signaling with GDC-0449 (Vismodegib) increases sensitivity to PTX-stimulated apoptosis. Furthermore, GDC-0449 potentiates PTX-induced reactive oxygen species and mitochondrial dysfunction. In contrast, a hedgehog agonist, Hh-Ag1.5, attenuates PTX-induced apoptosis. Mechanistic experiments revealed that hedgehog induces phosphorylation of Akt at Ser473. Akt then phosphorylates Bax at Ser184, which can switch its activity from pro-apoptosis to anti-apoptosis. Taken together, our findings suggest that inhibition of hedgehog signaling might be a promising therapeutic strategy to improve PTX response in EGFR WT NSCLC.

Post-Hypoxic Cells Promote Metastatic Recurrence after Chemotherapy Treatment in TNBC

Simple Summary

Intratumoral hypoxia is a negative prognostic factor in breast cancer progression and recurrence. By implementing a hypoxia fate-mapping system, we followed cells that experience intratumoral hypoxia in vivo and determined that these cells have an increased ability to metastasize compared to cells that were never exposed to hypoxia. In this work, we investigate whether cells that experienced intratumoral hypoxia are also resistant to chemotherapy. By utilizing both in vivo and ex vivo models, we conclude that metastatic cells found in the lung and liver, that were exposed to hypoxia in the primary tumor, are less sensitive to doxorubicin and paclitaxel and drive recurrence after treatment. Our studies also suggest that chemoresistance is associated with a cancer stem cell-like phenotype that is maintained in post-hypoxic cells.

Abstract

Hypoxia occurs in 90% of solid tumors and is associated with treatment failure, relapse, and mortality. HIF-1α signaling promotes resistance to chemotherapy in cancer cell lines and murine models via multiple mechanisms including the enrichment of breast cancer stem cells (BCSCs). In this work, we utilize a hypoxia fate-mapping system to determine whether triple-negative breast cancer (TNBC) cells that experience hypoxia in the primary tumor are resistant to chemotherapy at sites of metastasis. Using two orthotopic mouse models of TNBC, we demonstrate that cells that experience intratumoral hypoxia and metastasize to the lung and liver have decreased sensitivity to doxorubicin and paclitaxel but not cisplatin or 5-FU. Resistance to therapy leads to metastatic recurrence caused by post-hypoxic cells. We further determined that the post-hypoxic cells that metastasize are enriched in pathways related to cancer stem cell gene expression. Overall, our results show that even when hypoxic cancer cells are reoxygenated in the bloodstream they retain a hypoxia-induced cancer stem cell-like phenotype that persists and promotes resistance and eventually recurrence.

Proteomics analysis reveals the correlation of programmed ROS-autophagy loop and dysregulated G1/S checkpoint with imatinib resistance in chronic myeloid leukemia cells

Although tyrosine kinase inhibitors (TKIs), including imatinib, have greatly improved clinical treatment of patients with chronic myeloid leukemia (CML), drug resistance remains a major obstacle. Studies on the mechanisms underlying imatinib resistance and other alternative drugs are urgently needed. Liquid chromatography tandem mass spectrometry was applied to investigate the differences in proteomics and phosphoproteomics between K562 and K562/G (imatinib resistant K562). Multiple bioinformatics analyses were performed to unveil the differential signal pathways. CCK-8 was used to detect cell proliferation. Flow cytometry was performed to analyze reactive oxygen species (ROS), cell cycle, and cell apoptosis. Western blotting and quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) were used to observe the changes of ROS and autophagy associated with imatinib resistance in CML. Our results indicated that ROS-autophagy formed one negative feedback loop and was associated with imatinib resistance. Additionally, the limited-rate enzymes of serine synthesis pathway were escalated in K562/G, which could contribute to the increased cyclin-dependent kinases and cell proliferation index. According to phosphoproteomics data, K562/G cells exhibited abnormal phosphorylation of splicing signals. These results revealed that it could be one useful strategy to correct metabolism shift and oxidative stress, or moderately regulate autophagy. Future research should focus on the discovery of potential targets in ROS-autophagy loop.

Pathomechanisms of Paclitaxel-Induced Peripheral Neuropathy

Peripheral neuropathy is one of the most common side effects of chemotherapy, affecting up to 60% of all cancer patients receiving chemotherapy. Moreover, paclitaxel induces neuropathy in up to 97% of all gynecological and urological cancer patients. In cancer cells, paclitaxel induces cell death via microtubule stabilization interrupting cell mitosis. However, paclitaxel also affects cells of the central and peripheral nervous system. The main symptoms are pain and numbness in hands and feet due to paclitaxel accumulation in the dorsal root ganglia. This review describes in detail the pathomechanisms of paclitaxel in the peripheral nervous system. Symptoms occur due to a length-dependent axonal sensory neuropathy, where axons are symmetrically damaged and die back. Due to microtubule stabilization, axonal transport is disrupted, leading to ATP undersupply and oxidative stress. Moreover, mitochondria morphology is altered during paclitaxel treatment. A key player in pain sensation and axonal damage is the paclitaxel-induced inflammation in the spinal cord as well as the dorsal root ganglia. An increased expression of chemokines and cytokines such as IL-1β, IL-8, and TNF-α, but also CXCR4, RAGE, CXCL1, CXCL12, CX3CL1, and C3 promote glial activation and accumulation, and pain sensation. These findings are further elucidated in this review.

Paclitaxel-loaded polymeric nanoparticles based on α-tocopheryl succinate for the treatment of head and neck squamous cell carcinoma: in vivo murine model

The prognosis of patients with recurrent or metastatic head and neck squamous cell cancer (HNSCC) is generally poor. New treatments are required to supplement the current standard of care. Paclitaxel (PTX), an effective chemotherapeutic for HNSCC, has serious side effects. A polymeric nanocarrier system was developed for the delivery of PTX to improve HNSCC treatment. This study aimed to evaluate the antitumor efficacy of PTX-loaded polymeric nanoparticles based on α-TOS (PTX-NPs) administered by direct intratumoral injection into a Hypopharynx carcinoma squamous cells (FaDu) tumor xenograft mouse model. The nanocarrier system based on block copolymers of polyethylene glycol (PEG) and a methacrylic derivative of α-TOS was synthesized and PTX was loaded into the delivery system. Tumor volume was measured to evaluate the antitumor effect of the PTX-NPs. The relative mechanisms of apoptosis, cell proliferation, growth, angiogenesis, and oxidative and nitrosative stress were detected by Western blotting, fluorescent probes, and immunohistochemical analysis. The antitumor activity results showed that compared to free PTX, PTX-NPs exhibited much higher antitumor efficacy and apoptosis-inducing in a FaDu mouse xenograft model and demonstrated an improved safety profile. Ki-67, EGFR, and angiogenesis markers (Factor VIII, CD31, and CD34) expression were significantly lower in the PTX-NPs group compared with other groups (p < .05). Also, PTX-NPs induced oxidative and nitrosative stress in tumor tissue. Direct administration of PTX-loaded polymeric nanoparticles based on α-Tocopheryl Succinate at the tumor sites, proved to be promising for HNSCC therapy.

Evaluating the genetic basiss of anti-cancer property of Taxol in Saccharomyces cerevisiae model

Taxol has been regarded as one of the most successful anti-cancer drugs identified from natural sources to date. Although Taxol is known to sensitize cells by stabilizing microtubules, its ability to cause DNA damage in peripheral blood lymphocytes and to induce oxidative stress and apoptosis indicates that Taxol may have other modes of cytotoxic action. This study focuses on identifying the additional targets of Taxol that may contribute to its multifaceted cell killing property, using Saccharomyces cerevisiae. We show that yeast oxidative stress response mutants (sod1Δ, tsa1Δ and cta1Δ) and DNA damage response mutants (mre11∆, sgs1∆ and sub1∆) are highly sensitive to Taxol. Our results also show that Taxol increases the level of reactive oxygen species (ROS) in yeast oxidative stress response mutant strains. Further, 4',6-Diamidino-2'-phenylindole (DAPI) and acridine orange/ethidium bromide (AO/EB) staining show that Taxol induces apoptotic features such as nuclear fragmentation and chromatin condensation in DNA repair mutants. On the whole, our results suggest that Taxol's cytotoxic property is attributed to its multifaceted mechanism of action. Yeast S. cerevisiae anti-oxidant and DNA repair gene mutants are sensitive to Taxol compared to wild-type, suggesting yeast model can be used to identify the genetic targets of anti-cancer drugs.

Achillea millefolium alleviates testicular damage in paclitaxel-intoxicated rats via attenuation of testicular oxido-inflammatory stress and apoptotic responses

The aim of this study was to investigate the effects of Achillea millefolium extract in paclitaxel-induced testicular toxicity in rats. The groups were designed as (1) control, (2) paclitaxel (8 mg/kg, intraperitoneally), (3) paclitaxel (8 mg/kg, intraperitoneally) + Achillea millefolium (200 mg/kg, orally for 14 consecutive days) and (4) paclitaxel (8 mg/kg, intraperitoneally) + Achillea millefolium (400 mg/kg, orally for 14 consecutive days). Serum levels of testosterone, luteinising hormone and follicle-stimulating hormone, as well as total antioxidant capacity and total oxidant status were measured one day after receiving the last dose of Achillea millefolium extract. Testicular superoxide dismutase activity, malondialdehyde, tumour necrosis factor alpha and interleukin-1β levels, the expressions of nuclear factor kappa B and caspase-3 were evaluated. In addition, testicular sections were evaluated histopathologically and 8-hydroxy-2'-deoxyguanosine was detected immunohistochemically. Achillea millefolium improved the levels of luteinising hormone, follicle-stimulating hormone and testosterone, upregulated testicular antioxidant enzymes and downregulated inflammation. Furthermore, we observed that Achillea millefolium restored testicular histopathological structure and significantly suppressed oxidative DNA damage and apoptosis by reducing the expression of caspase-3. Taken together, our results suggest that Achillea millefolium has protective effects against paclitaxel-induced testicular toxicity and is a promising natural product with the potential to improve male fertility.

A novel synergistic anticancer effect of fungal cholestanol glucoside and paclitaxel: Apoptosis induced by an intrinsic pathway through ROS generation in cervical cancer cell line (HeLa)

In the search for efficient therapeutics with economically viable for cancer treatment, combination therapy has developed as a keystone in the pursuit of novel approaches for drug discovery. In this regard, we confirmed the presence of cholestanol glucoside (CG) in Lasiodiplodia theobromae culture filtrate and its production was estimated to be 20.01 mg/l. The purified fungal CG was obtained with a molecular mass of 550.18 m/z. The combination of CG and paclitaxel (PTX) was found to have potent cytotoxicity against HeLa cells. We revealed that the synergistic effect of CG and PTX induced apoptosis through the formation of nuclear fragments, DNA fragmentation and sub G1 cell cycle arrest. Further, it was proven that apoptosis took place by loss of the mitochondrial membrane potential (MMP) through reactive oxygen species (ROS) production and caspase 3/7 activity. Moreover, the data suggests that the synergistic effect of CG and PTX played a role in a mitochondrial intrinsic pathway through the apoptotic gene expression of Bax, caspase-9 and caspase-3. In addition, the down-regulation of Bcl-2 strongly described the induced apoptosis through an intrinsic pathway using the Western blot analysis. The conclusion of this study is that a combination of CG and PTX has synergistic apoptotic effects in HeLa cells, which provides a possible therapeutic strategy for cancer therapy in the future.

Oxidative resistance of leukemic stem cells and oxidative damage to hematopoietic stem cells under pro-oxidative therapy

Leukemic stem cells (LSCs) and hematopoietic stem cells (HSCs) are both dependent on the hypoxic bone marrow (BM) microenvironment (also known as the BM niche). There is always fierce competition between the two types of cells, and the former exhibits a greater competitive advantage than the latter via multiple mechanisms. Under hypoxia, the dynamic balance between the generation and clearing of intracellular reactive oxygen species (ROS) is conducive to maintaining a quiescent state of cells. Quiescent LSCs can reside well in the BM niche, avoiding attack by chemotherapeutic agents, which is the cause of chemotherapeutic resistance and relapse in leukemia. HSCs acquire energy mainly through anaerobic glycolysis, whereas LSCs achieve energy metabolism largely through mitochondrial oxidative respiration. Mitochondria are the primary site of ROS generation. Thus, in theory, mitochondria-mediated respiration will cause an increase in ROS generation in LSCs and a higher intracellular oxidative stress level. The sensitivity of the cells to pro-oxidant drugs increases as well, which allows for the selective clearing of LSCs by pro-oxidative therapy. However, HSCs are also highly sensitive to changes in ROS levels, and the toxic effects of pro-oxidant drugs on HSCs poses a major challenge to pro-oxidative therapy in leukemia. Given the above facts, we reviewed studies on the oxidative resistance of LSCs and the oxidative damage to HSCs under pro-oxidative therapy. An in-depth investigation into the oxidative stress status and regulatory mechanisms of LSCs and HSCs in hypoxic environments will promote our understanding of the survival strategy employed by LSCs and the mechanism of the oxidative damage to HSCs in the BM niche, thus facilitating individualized treatment of leukemia patients and helping eliminate LSCs without disturbing normal hematopoietic cells.

Effect of monosodium glutamate on testicular tissue of paclitaxel-treated mice: An experimental study

Background

Paclitaxel (PTX), a chemotherapeutic agent, and monosodium glutamate (MSG) have oxidative effects on testicular tissue.

Objective

In this study, the effects of MSG administration on the exacerbation of testicular tissue alterations related to PTX treatment were evaluated.

Materials and Methods

MSG (30 & 60 mg/kg i.p.) was administrated to six groups (n = 8/each) of adult mice before or after PTX treatment: control, PTX-treated, MSG30 + PTX, MSG60 + PTX, PTX + MSG30, and PTX + MSG60. Following the euthanizing, the body weight measurement, pituitary-testicular axis hormonal analysis and serum lipid peroxidation index assessment was prepared, testicular histomorphometry (tubular diameter and germinal epithelium height), immunohistochemistry of p53 was completed. Microscopic indices of spermatogenesis (tubular differentiation, spermiogenesis and repopulation indices) were studied.

Results

Body weight was not changed significantly. The levels of testosterone (p = 0.0001), follicle stimulating hormone (p = 0.019), and luteinizing hormone (p = 0.08) were decreased while the level of lipid peroxidation index was increased (p = 0.208) in the treated groups. The histomorphometry indices (p < 0.0001 and p = 0.001, respectively), germ cells population (p < 0.05) and microscopic indices of spermatogenesis (p = 0.001, p = 0.005, p < 0.0001, respectively) were significantly reduced in all treated groups. The administration of MSG before PTX treatment induces more changes. The most positive reaction to p53 was observed in MSG30 or 60 + PTX groups compared to other groups.

Conclusion

The administration of MSG could intensify testicular tissue alterations related to PTX chemotherapy.

Impact of ROS Generated by Chemical, Physical, and Plasma Techniques on Cancer Attenuation

For the last few decades, while significant improvements have been achieved in cancer therapy, this family of diseases is still considered one of the deadliest threats to human health. Thus, there is an urgent need to find novel strategies in order to tackle this vital medical issue. One of the most pivotal causes of cancer initiation is the presence of reactive oxygen species (ROS) inside the body. Interestingly, on the other hand, high doses of ROS possess the capability to damage malignant cells. Moreover, several important intracellular mechanisms occur during the production of ROS. For these reasons, inducing ROS inside the biological system by utilizing external physical or chemical methods is a promising approach to inhibit the growth of cancer cells. Beside conventional technologies, cold atmospheric plasmas are now receiving much attention as an emerging therapeutic tool for cancer treatment due to their unique biophysical behavior, including the ability to generate considerable amounts of ROS. This review summarizes the important mechanisms of ROS generated by chemical, physical, and plasma approaches. We also emphasize the biological effects and cancer inhibition capabilities of ROS.

R. R, Thomas S, Nisha P. Short chain fatty acids enriched fermentation metabolites of soluble dietary fibre from Musa paradisiaca drives HT29 colon cancer cells to apoptosis

In this study, the prebiotic potential of soluble dietary fibre extracted from plantain inflorescence (PIF) was investigated. PIF demonstrated prebiotic potential by enhancing the growth of the probiotics under study and thereby hindered colon cancer development. The soluble dietary fibre from Musa paradisiaca inflorescence (PIF) was fermented using Lactobacillus casei and Bifidobacterium bifidum. The fermentation supernatants (LS and BS) were enriched with short chain fatty acids (SCFA) and were able to initiate apoptotic signalling in HT29 colon cancer cells leading to cell death. Both BS and LS exhibited cytotoxic effect; induced DNA damage and enhanced generation of reactive oxygen species in HT29 cells leading to apoptosis. The induction of apoptosis was facilitated by the reduction of membrane potential of mitochondria and ATP synthesis; enhanced delivery of cytochrome c and interference with the expression of pro/antiapoptotic proteins. BS, which exhibited better activity, was further analysed for the identification of differentially regulated proteins by performing two dimensional electrophoresis and MALDI-TOF mass spectrometry. Results emphasized on the fact that, the exposure to BSalteredthe HT29 proteins expression, particularly the upregulation of apoptosis- inducing factor-AIFM1 leading to apoptosis of HT29 cells.

Inositol-triphosphate 3-kinase B confers cisplatin resistance by regulating NOX4-dependent redox balance

How altered metabolism contributes to chemotherapy resistance in cancer cells remains unclear. Through a metabolism-related kinome RNAi screen, we identified inositol-trisphosphate 3-kinase B (ITPKB) as a critical enzyme that contributes to cisplatin-resistant tumor growth. We demonstrated that inositol 1,3,4,5-tetrakisphosphate (IP4), the product of ITPKB, plays a critical role in redox homeostasis upon cisplatin exposure by reducing cisplatin-induced ROS through inhibition of a ROS-generating enzyme, NADPH oxidase 4 (NOX4), which promotes cisplatin-resistant tumor growth. Mechanistically, we identified that IP4 competes with the NOX4 cofactor NADPH for binding and consequently inhibits NOX4. Targeting ITPKB with shRNA or its small-molecule inhibitor resulted in attenuation of NOX4 activity, imbalanced redox status, and sensitized cancer cells to cisplatin treatment in patient-derived xenografts. Our findings provide insight into the crosstalk between kinase-mediated metabolic regulation and platinum-based chemotherapy resistance in human cancers. Our study also suggests a distinctive signaling function of IP4 that regulates NOX4. Furthermore, pharmaceutical inhibition of ITPKB displayed synergistic attenuation of tumor growth with cisplatin, suggesting ITPKB as a promising synthetic lethal target for cancer therapeutic intervention to overcome cisplatin resistance.

Chemoradiation induces epithelial-to-mesenchymal transition in esophageal adenocarcinoma

Multimodality treatment has advanced the outcome of esophageal adenocarcinoma (EAC), but overall survival remains poor. Therapeutic pressure activates effective resistance mechanisms and we characterized these mechanisms in response to the currently used neoadjuvant treatment against EAC: carboplatin, paclitaxel and radiotherapy. We developed an in vitro approximation of this regimen and applied it to primary patient‐derived cultures. We observed a heterogeneous epithelial‐to‐mesenchymal (EMT) response to the high therapeutic pressure exerted by chemoradiation. We found EMT to be initiated by the autocrine production and response to transforming growth factor beta (TGF‐β) of EAC cells. Inhibition of TGF‐β ligands effectively abolished chemoradiation‐induced EMT. Assessment of TGF‐β serum levels in EAC patients revealed that high levels after neoadjuvant treatment predicted the presence of fluorodeoxyglucose uptake in lymph nodes on the post‐chemoradiation positron emission tomography‐scan. Our study shows that chemoradiation contributes to resistant metastatic disease in EAC patients by inducing EMT via autocrine TGF‐β production. Monitoring TGF‐β serum levels during treatment could identify those patients at risk of developing metastatic disease, and who would likely benefit from TGF‐β targeting therapy.

What's new?

Therapeutic resistance and disease recurrence are major setbacks affecting the survival of patients with esophageal adenocarcinoma (EAC). Resistance mechanisms in EAC, however, await elucidation. Here, epithelial‐to‐mesenchymal transition (EMT), a hallmark of invasive tumor phenotype, was investigated as a possible mechanism driving chemoradiation resistance in EAC. In EAC cells, chemoradiation was found to induce EMT, a process mediated via autocrine TGF‐β production. Inhibition of TGF‐β counteracted this process. In patients, elevated circulating TGF‐β levels post‐chemoradiation were associated with progressive disease. Together, these data suggest that TGF‐β is a useful marker for identifying patients who might benefit from TGF‐β inhibition during chemoradiation.

Intracellular catalase activity instead of glutathione level dominates the resistance of cells to reactive oxygen species

Artesunate (ARS) induced significant reactive oxygen species (ROS) generation in HepG2, HeLa, and A549 lines. However, ARS induced ROS-dependent apoptosis in HeLa and A549 cell lines but ROS-independent apoptosis in HepG2 cells. A total of 200 μM hydrogen peroxide (H2O2) significantly induced cytotoxicity in HeLa cells, while H2O2 up to 300 μM did not induce cytotoxicity in HepG2 cells, further demonstrating the strong resistance of HepG2 cells to ROS. HeLa cells had much higher basic total glutathione (T-GSH) level than HepG2 cells, while the ratio of basic reduced glutathione (GSH)/oxidized glutathione (GSSG) in HepG2 cells was nearly twice than that in HeLa and A549 cells. Inhibition of glutathione markedly enhanced H2O2- or ARS-induced cytotoxicity in HeLa and A549 cell lines but modestly enhanced the cytotoxicity of H2O2 and even did not affect the cytotoxicity of ARS in HepG2 cells. Moreover, addition of GSH remarkably prevented H2O2- or ARS-induced cytotoxicity in HeLa and A549 cell lines, further indicating the involvement of GSH in scavenging ROS in the two cell lines. HepG2 cells exhibited higher catalase activity than HeLa cells, and inhibiting catalase activity by using 3-aminotriazole (3-AT, a specific inhibition of catalase) or catalase siRNA remarkably reduced the resistance of HepG2 cells to ROS, demonstrating the key roles of catalase for the strong resistance of HepG2 cells to ROS. Collectively, catalase activity instead of glutathione level dominates the resistance of cells to ROS.

Paclitaxel suppresses proliferation and induces apoptosis through regulation of ROS and the AKT/MAPK signaling pathway in canine mammary gland tumor cells

Paclitaxel is a diterpenoid compound, derived from the pacific yew (Taxus brevifolia) berry, which exhibits antineoplastic effects against various types of cancer. However, the antitumor effects and the molecular mechanisms of paclitaxel on canine CHMm cells remain to be elucidated. The aim of the present study was to investigate the antitumor effects of paclitaxel on CHMm cells and identify relevant signal transduction pathways modulated by paclitaxel using multiple methods including MTT assay, flow cytometry, acridine orange/ethidium bromide staining, transmission electron microscopy, determination of cellular reactive oxygen species (ROS), superoxide dismutase (SOD) and malondiadehyde (MDA) and western blotting, the data indicated that paclitaxel decreased cell viability, induced G₂/M-phase cell cycle arrest, suppressed the expression of cyclin B1 and induced apoptosis in a dose-dependent manner. In addition, paclitaxel upregulated the expression of Bax and cytochrome c, but reduced expression of apoptosis regulator Bcl-2, resulting in activation of caspase-3, chromatin condensation, karyopyknosis, intracellular vacuolization, increased production of ROS and MDA, and decreased activity of SOD. However, these effects were inhibited when CHMm cells were treated with N-acetyl-L-cysteine. Furthermore, treatment with paclitaxel inhibited the level of of phospho (p)-RAC-α serine/threonine-protein kinase (AKT) and p-ribosomal protein S6 kinase proteins, and promoted phosphorylation of P38 mitogen-activated protein kinase (MAPK) and p-90 kDa ribosomal protein S6 kinase 1 proteins in CHMm cells. It was observed that paclitaxel in combination with pharmacological inhibitors of the P38 and phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) signaling pathways (SB203580 and LY294002, respectively) exerted synergistic inhibitory effects on the proliferation of the CHMm cells. The results of the present study demonstrated that paclitaxel inhibited tumor cell proliferation by increasing intrinsic apoptosis through inhibition of the PI3K/AKT signaling pathway and activation of MAPK signaling pathway in CHMm cells.

Autophagy protects ovarian cancer-associated fibroblasts against oxidative stress

RNA-Seq and gene set enrichment anylysis revealed that ovarian cancer associated fibroblasts (CAFs) are mitotically active compared with normal fibroblasts (NFs). Cellular senescence is observed in CAFs treated with H₂O₂ as shown by elevated SA-β-gal activity and p21 (WAF1/Cip1) protein levels. Reactive oxygen species (ROS) production and p21 (WAF1/Cip1) elevation may account for H₂O₂-induced CAFs cell cycle arrest in S phase. Blockage of autophagy can increase ROS production in CAFs, leading to cell cycle arrest in S phase, cell proliferation inhibition and enhanced sensitivity to H₂O₂-induced cell death. ROS scavenger NAC can reduce ROS production and thus restore cell viability. Lactate dehydrogenase A (LDHA), monocarboxylic acid transporter 4 (MCT4) and superoxide dismutase 2 (SOD2) were up-regulated in CAFs compared with NFs. There was relatively high lactate content in CAFs than in NFs. Blockage of autophagy decreased LDHA, MCT4 and SOD2 protein levels in CAFs that might enhance ROS production. Blockage of autophagy can sensitize CAFs to chemotherapeutic drug cisplatin, implicating that autophagy might possess clinical utility as an attractive target for ovarian cancer treatment in the future.

Cytotoxic effect of albumin coated copper nanoparticle on human breast cancer cells of MDA-MB 231

PURPOSE

The aim of this study was to design a new nanocomposite that would have high cytotoxicity against invasive breast cancer cells and minimum side effects on normal cells.

METHODS

An albumin nano-carrier for delivery of CuNPs was developed. The ACuNPs formation was characterized by TEM, DLS and UV-Vis, fluorescence and circular dichroism spectroscopy. The cytotoxic efficacy of the ACuNPs against human breast cancer cells (MDA-MB 231) and normal cells (MCF-10A) was compared using a standard MTT assay. The mechanism of cell death induced by ACuNPs was considered by inverted and fluorescent microscopy, flow cytometry and gel electrophoresis. The effects of compounds on ROS generations in MDA-MB 231 cells were also studied.

RESULTS

It was found that the resulted ACuNPs with a diameter of 62.7 nm and zeta potential of about -10.76 mV, are suitable for extravasation into tumor cells. In ACuNPs, the 90% of the secondary structure and almost all the tertiary structure of albumin remained intact. Comparing to CuNPs, ACuNPs could significantly suppress the viability of cancer cells while they were less toxic on normal cells. Compared with the untreated cells, the MDA-MB 231 cell line showed higher levels of ROS production after treatment with ACuNPs. The increase in ROS production after 24 hours indicated that ACuNPs induce apoptosis.

CONCLUSIONS

The ACuNPs characteristics such as intact structure of albumin, high toxicity against cancer cells comparing to normal cells and apoptosis induction as the mechanism of cell death, revealed that this nanocomposite is a good candidate to be used as a chemotherapeutic agent against invasive breast cancer cells.

Evaluation of the cytotoxicity of the Bithionol-paclitaxel combination in a panel of human ovarian cancer cell lines

Previously, Bithionol (BT) was shown to enhance the chemosensitivity of ovarian cancer cell lines to cisplatin treatment. In the present study, we focused on the anti-tumor potential of the BT-paclitaxel combination when added to a panel of ovarian cancer cell lines. This in vitro study aimed to 1) determine the optimum schedule for combination of BT and paclitaxel and 2) assess the nature and mechanism(s) underlying BT-paclitaxel interactions. The cytotoxic effects of both drugs either alone or in combination were assessed by presto-blue cell viability assay using six human ovarian cancer cell lines. Inhibitory concentrations to achieve 50% cell death (IC₅₀) were determined for BT and paclitaxel in each cell line. Changes in levels of cleaved PARP, XIAP, bcl-2, bcl-xL, p21 and p27 were determined via immunoblot. Luminescent and colorimetric assays were used to determine caspases 3/7 and autotaxin (ATX) activity. Cellular reactive oxygen species (ROS) were measured by flow cytometry. Our results show that the efficacy of the BT-paclitaxel combination depends upon the concentrations and sequence of addition of paclitaxel and BT. Pretreatment with BT followed by paclitaxel resulted in antagonistic interactions whereas synergistic interactions were observed when both drugs were added simultaneously or when cells were pretreated with paclitaxel followed by BT. Synergistic interactions between BT and paclitaxel were attributed to increased ROS generation and enhanced apoptosis. Decreased expression of pro-survival factors (XIAP, bcl-2, bcl-xL) and increased expression of pro-apoptotic factors (caspases 3/7, PARP cleavage) was observed. Additionally, increased expression of key cell cycle regulators p21 and p27 was observed. These results show that BT and paclitaxel interacted synergistically at most drug ratios which, however, was highly dependent on the sequence of the addition of drugs. Our results suggest that BT-paclitaxel combination therapy may be effective in sensitizing ovarian cancer cells to paclitaxel treatment, thus mitigating some of the toxic effects associated with high doses of paclitaxel.

Anti-cancerous effect of albumin coated silver nanoparticles on MDA-MB 231 human breast cancer cell line

With the aim of making specific targeting of silver nanoparticles as a drug for tumor cells and developing new anticancer agents, a novel nano-composite was developed. Albumin coated silver nanoparticles (ASNPs) were synthesized, and their anti-cancerous effects were evaluated against MDA-MB 231, a human breast cancer cell line. The synthesized ASNPs were characterized by spectroscopic methods. The morphological changes of the cells were observed by inverted, florescent microscopy and also by DNA ladder pattern on gel electrophoresis; the results revealed that the cell death process occurred through the apoptosis mechanism. It was found that ASNPs with a size of 90 nm and negatively charged with a zeta-potential of about −20 mV could be specifically taken up by tumor cells. The LD₅₀ of ASNPs against MDA-MB 231 (5 μM), was found to be 30 times higher than that for white normal blood cells (152 μM). The characteristics of the synthesized ASNPs included; intact structure of coated albumin, higher cytotoxicity against cancer cells than over normal cells, and cell death based on apoptosis and reduction of gland tumor sizes in mice. This work indicates that ASNPs could be a good candidate for chemotherapeutic drug.

Evaluation of the cytotoxicity of the Bithionol - cisplatin combination in a panel of human ovarian cancer cell lines

Background

Combination drug therapy appears a promising approach to overcome drug resistance and reduce drug-related toxicities in ovarian cancer treatments. In this in vitro study, we evaluated the antitumor efficacy of cisplatin in combination with Bithionol (BT) against a panel of ovarian cancer cell lines with special focus on cisplatin-sensitive and cisplatin-resistant cell lines. The primary objectives of this study are to determine the nature of the interactions between BT and cisplatin and to understand the mechanism(s) of action of BT-cisplatin combination.

Methods

The cytotoxic effects of drugs either alone or in combination were evaluated using presto-blue assay. Cellular reactive oxygen species were measured by flow cytometry. Immunoblot analysis was carried out to investigate changes in levels of cleaved PARP, XIAP, bcl-2, bcl-xL, p21 and p27. Luminescent and colorimetric assays were used to test caspases 3/7 and ATX activity.

Results

The efficacy of the BT-cisplatin combination depends upon the cell type and concentrations of cisplatin and BT. In cisplatin-sensitive cell lines, BT and cisplatin were mostly antagonistic except when used at low concentrations, where synergy was observed. In contrast, in cisplatin-resistant cells, BT-cisplatin combination treatment displayed synergistic effects at most of the drug ratios/concentrations. Our results further revealed that the synergistic interaction was linked to increased reactive oxygen species generation and apoptosis. Enhanced apoptosis was correlated with loss of pro-survival factors (XIAP, bcl-2, bcl-xL), expression of pro-apoptotic markers (caspases 3/7, PARP cleavage) and enhanced cell cycle regulators p21 and p27.

Conclusion

In cisplatin-resistant cell lines, BT potentiated cisplatin-induced cytotoxicity at most drug ratios via enhanced ROS generation and modulation of key regulators of apoptosis. Low doses of BT and cisplatin enhanced efficiency of cisplatin treatment in all the ovarian cancer cell lines tested. Our results suggest that novel combinations such as BT and cisplatin might be an attractive therapeutic approach to enhance ovarian cancer chemosensitivity. Combining low doses of cisplatin with subtherapeutic doses of BT can ultimately lead to the development of an innovative combination therapy to reduce/prevent the side effects normally occurring when high doses of cisplatin are administered.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-3034-2) contains supplementary material, which is available to authorized users.

Mitochondrial PKM2 regulates oxidative stress-induced apoptosis by stabilizing Bcl2

Pyruvate kinase M2 isoform (PKM2) catalyzes the last step of glycolysis and plays an important role in tumor cell proliferation. Recent studies have reported that PKM2 also regulates apoptosis. However, the mechanisms underlying such a role of PKM2 remain elusive. Here we show that PKM2 translocates to mitochondria under oxidative stress. In the mitochondria, PKM2 interacts with and phosphorylates Bcl2 at threonine (T) 69. This phosphorylation prevents the binding of Cul3-based E3 ligase to Bcl2 and subsequent degradation of Bcl2. A chaperone protein, HSP90α1, is required for this function of PKM2. HSP90α1's ATPase activity launches a conformational change of PKM2 and facilitates interaction between PKM2 and Bcl2. Replacement of wild-type Bcl2 with phosphorylation-deficient Bcl2 T69A mutant sensitizes glioma cells to oxidative stress-induced apoptosis and impairs brain tumor formation in an orthotopic xenograft model. Notably, a peptide that is composed of the amino acid residues from 389 to 405 of PKM2, through which PKM2 binds to Bcl2, disrupts PKM2-Bcl2 interaction, promotes Bcl2 degradation and impairs brain tumor growth. In addition, levels of Bcl2 T69 phosphorylation, conformation-altered PKM2 and Bcl2 protein correlate with one another in specimens of human glioblastoma patients. Moreover, levels of Bcl2 T69 phosphorylation and conformation-altered PKM2 correlate with both grades and prognosis of glioma malignancy. Our findings uncover a novel mechanism through which mitochondrial PKM2 phosphorylates Bcl2 and inhibits apoptosis directly, highlight the essential role of PKM2 in ROS adaptation of cancer cells, and implicate HSP90-PKM2-Bcl2 axis as a potential target for therapeutic intervention in glioblastoma.

Inhibition of Ras/Raf/MEK/ERK Pathway Signaling by a Stress-Induced Phospho-Regulatory Circuit

Ras pathway signaling plays a critical role in cell growth control and is often upregulated in human cancer. The Raf kinases selectively interact with GTP-bound Ras and are important effectors of Ras signaling, functioning as the initiating kinases in the ERK cascade. Here, we identify a route for the phospho-inhibition of Ras/Raf/MEK/ERK pathway signaling that is mediated by the stress-activated JNK cascade. We find that key Ras pathway components, the RasGEF Sos1 and the Rafs, are phosphorylated on multiple S/TP sites in response to JNK activation and that the hyperphosphorylation of these sites renders the Rafs and Sos1 unresponsive to upstream signals. This phospho-regulatory circuit is engaged by cancer therapeutics, such as rigosertib and paclitaxel/Taxol, that activate JNK through mitotic and oxidative stress as well as by physiological regulators of the JNK cascade and may function as a signaling checkpoint to suppress the Ras pathway during conditions of cellular stress.

Phytomedicine-Modulating oxidative stress and the tumor microenvironment for cancer therapy

In spite of the current advances and achievements in systems biology and translational medicinal research, the current strategies for cancer therapy, such as radiotherapy, targeted therapy, immunotherapy and chemotherapy remain palliative or unsatisfactory due to tumor metastasis or recurrence after surgery/therapy, drug resistance, adverse side effects, and so on. Oxidative stress (OS) plays a critical role in chronic/acute inflammation, carcinogenesis, tumor progression, and tumor invasion/metastasis which is also attributed to the dynamic and complex properties and activities in the tumor microenvironment (TME). Re-educating or reprogramming tumor-associated stromal or immune cells in the TME provides an approach for restoring immune surveillance impaired by disease in cancer patients to increase overall survival and reduce drug resistance. Herbal medicines or plant-derived natural products have historically been a major source of anti-cancer drugs. Delving into the lore of herbal medicine may uncover new leads for anti-cancer drugs. Phytomedicines have been widely documented to directly or indirectly target multiple signaling pathways and networks in cancer cells. A combination of anti-cancer drugs and polypharmacological plant-derived extracts or compounds may offer a significant advantage in sensitizing the efficacy of monotherapy and overcoming drug-induced resistance in cancer patients. This review introduces several phytochemicals and phytoextracts derived from medicinal plants or dietary vegetables that have been studied for their efficacy in preclinical cancer models. We address the underlying modes of action of induction of OS and deregulation of TME-associated stromal cells, mediators and signaling pathways, and reference the related clinical investigations that look at the single or combination use of phytochemicals and phytoextracts to sensitize anti-cancer drug effects and/or overcome drug resistance.

Acetylation at lysine 71 inactivates superoxide dismutase 1 and sensitizes cancer cells to genotoxic agents

Cancer cells are characterized by a high dependency on antioxidant enzymes to cope with the elevated rates of reactive oxygen species (ROS). Impairing antioxidant capacity in cancer cells disturbs the ROS homeostasis and exposes cancer cells to massive oxidative stress. In this study, we have discovered that superoxide dismutase 1 (SOD1), a major player in maintaining the cellular redox status, was acetylated at lysine 71. This acetylation, which was primarily deacetylated by Sirtuin 1 (SIRT1), suppressed the enzymatic activity of SOD1 via disrupting its association with copper chaperone for SOD1 (CCS). More importantly, genotoxic agents, such as camptothecin (CPT), induced SOD1 acetylation by disrupting its binding with SIRT1. CPT-induced SOD1 acetylation was stimulated by its provoked ROS, suggesting a positive feedback loop, in which ROS per se impairs the antioxidative defence of cancer cells and reinforces oxidative stress stimulated by anticancer agents. The intrinsic abundance of SOD1 acetylation varied among cancer cells, and high level of SOD1 acetylation was correlated with elevated sensitivity to CPT. Together, our findings gained mechanistic insights into how cytotoxic agents fine tune the intracellular ROS homeostasis to strengthen their anticancer effects, and suggested SOD1 acetylation as a candidate biomarker for predicting response to CPT-based chemotherapy.

How plausible is the use of dietary n-3 PUFA in the adjuvant therapy of cancer?

Considerable debate exists regarding the potential antineoplastic effect of dietary long-chain n-3 PUFA contained in fatty fishes. Since the majority of published data has proven that their intake does not induce toxic or carcinogenic effects in humans, their possible preventive use against cancer has been suggested. On the other hand, it is unlikely that they could be effective in cancer patients as a single therapy. Nevertheless, a considerable effort has been put forth in recent years to evaluate the hypothesis that n-3 PUFA might improve the antineoplastic efficiency of currently used anticancer agents. The rationale for this therapeutic combinatory strategy is trying to increase cancer sensitivity to conventional therapies. This could allow the use of lower drug/radiation doses and, thereby, a reduction in the detrimental health effects associated with these treatments. We will here critically examine the studies that have investigated this possibility, by focusing particularly on the biological and molecular mechanisms underlying the antineoplastic effect of these combined treatments. A possible use of n-3 PUFA in combination with the innovative single-targeted anti-cancer therapies, that often are not completely devoid of dangerous side-effects, is also suggested.

Biomedical properties and potentiality of Lippia microphylla Cham. and its essential oils

Lippia microphylla Cham. (Verbenaceae) is an endemic underexploited Brazilian vegetal. This work reviewed the biological potentialities of Lippia microphylla, emphasizing the properties of essential oils (EOs) and analyzed scientific indicators about genus Lippia and L. microphylla. Databases from 1948 to the present were searched and a software (vantage point 7.1) associated with Derwent Innovation Index was used to identify the indicators of the genus Lippia, and biological activities and compounds in the L. macrophylla species. Ethnopharmacological records report use of L. microphylla leaves to treat gastrointestinal disorders, influenza, bronchitis, cough, nasal congestion, and sinusitis during vaporization, whose aromatic volatile oils are rich in monoterpenes, especially cineole, terpineol, and thymol. Other EOs have larvicidal activity on Aedes aegypti larvae, and antifungal, antibacterial and cytotoxic and antitumor action on human and murine cancer cells. Brazil is the country with more articles about Lippia species, but it deposited only 9 patents since 1993. Most of the publications about L. microphylla are concentrated in food and chemical sciences. This bioprospection helps to choice areas of interest for capital investment and to give support for Brazilian Institutions to establish cooperation and improve technological impact at the point of view of creation and innovation.

LC-based targeted metabolomics analysis of nucleotides and identification of biomarkers associated with chemotherapeutic drugs in cultured cell models

Treatment of mammalian cells with chemotherapeutic drugs can result in perturbations of nucleotide pools. Monitoring these perturbations in cultured tumor cells from human sources is useful for assessment of the effect of drug therapy and a better understanding of the mechanism of action of these drugs. In this study, three classes of chemotherapeutic drugs with different mechanisms of action were used in the development of drug-treated cell models. The LC-based targeted metabolomics analysis of nucleotides in cells of the control group and the drug-treated group was carried out. Several data processing methods were combined for the identification of potential biomarkers associated with the action of drugs, including one-way analysis of variance, principal component analysis, and receiver operating characteristic curves. Intriguingly, tumor cells of both the control group and the drug-treated groups can be distinguished from each other, and several variables were recognized as potential biomarkers, such as ATP, GMP, and UDP for antimetabolite agents, ATP, GMP, and CTP for DNA-damaging agents, as well as GMP, ATP, UDP, and GDP for the mitotic spindle agents. Further validation of the potential biomarkers was performed using the receiver operating characteristic curve. Considering their corresponding area under the curve, which was larger than 0.9, it can be concluded that GMP and ATP are the best potential biomarkers for DNA-damaging drugs, as well as GMP, ATP, and UDP for the other two classes of drugs. This limited nucleotide approach cannot completely distinguish the mechanisms of the nine drugs, but it provides preliminary evidence for the role of pharmacometabolomics in the preclinical development of drugs at least.

SENIEUR status of the originating cell donor negates certain 'anti-immunosenescence' effects of ebselen and N-acetyl cysteine in human T cell clone cultures

Background

Damage to T cells of the immune system by reactive oxygen species may result in altered cell function or cell death and thereby potentially impact upon the efficacy of a subsequent immune response. Here, we assess the impact of the antioxidants Ebselen and N-acetyl cysteine on a range of biological markers in human T cells derived from a SENIEUR status donor. In addition, the impact of these antioxidants on different MAP kinase pathways in T cells from donors of different ages was also examined.

Methods

T cell clones were derived from healthy 26, 45 and SENIEUR status 80 year old people and the impact of titrated concentrations of Ebselen or N-acetyl cysteine on their proliferation and in vitro lifespan, GSH:GSSG ratio as well as levels of oxidative DNA damage and on MAP kinase signaling pathways was examined.

Results

In this investigation neither Ebselen nor N-acetyl cysteine supplementation had any impact on the biological endpoints examined in the T cells derived from the SENIEUR status 80 year old donor. This is in contrast to the anti-immunosenescent effects of these antioxidants on T cells from donors of 26 or 45 years of age. The analysis of MAP kinases showed that pro-apoptotic pathways become activated in T cells with increasing in vitro age and that Ebselen or N-acetyl cysteine could decrease activation (phosphorylation) in T cells from 26 or 45 year old donors, but not from the SENIEUR status 80 year old donor.

Conclusions

The results of this investigation demonstrate that the biological phenotype of SENIEUR status derived human T cells negates the anti-immunosenescence effects of Ebselen and also N-acetyl cysteine. The results highlight the importance of pre-antioxidant intervention evaluation to determine risk-benefit.

Electronic supplementary material

The online version of this article (doi:10.1186/s12979-014-0017-5) contains supplementary material, which is available to authorized users.

Antiproliferative and apoptotic effects of Sesbania grandiflora leaves in human cancer cells

Natural phytochemicals and their derivatives are good drug candidates for anticancer therapeutic approaches against multiple targets. We report here the initial findings from our studies on the anticancer properties of the leaves of the medicinal plant Sesbania grandiflora. In the current study, five different solvent fractions from the leaves of S. grandiflora were tested on cancer cell lines such as MCF-7, HepG2, Hep-2, HCT-15, and A549. The methanolic fraction of S. grandiflora was found to exert potent antiproliferative effects especially in the human lung cancer cell line, A549. Caspase 3 was activated in the methanolic fraction treated A549 cells thereby leading to cell death by apoptosis. DAPI staining, DNA laddering, and decrease in mitochondrial membrane potential further confirmed the apoptotic mode of cell death. The high levels of ROS intermediates as evidenced by DCF-DA staining could have played a role in the apoptotic induction. Decrease in levels of cyclin D1 and decrease in the activation of NFkB were observed in A549 cells on treatment with methanolic fraction, giving a hint on the possible mechanism of action. These results prove that the medicinal plant S. grandiflora can be explored further for promising candidate molecules to combat cancer, especially lung cancer.

Bithionol inhibits ovarian cancer cell growth in vitro - studies on mechanism(s) of action

Background

Drug resistance is a cause of ovarian cancer recurrence and low overall survival rates. There is a need for more effective treatment approaches because the development of new drug is expensive and time consuming. Alternatively, the concept of ‘drug repurposing’ is promising. We focused on Bithionol (BT), a clinically approved anti-parasitic drug as an anti-ovarian cancer drug. BT has previously been shown to inhibit solid tumor growth in several preclinical cancer models. A better understanding of the anti-tumor effects and mechanism(s) of action of BT in ovarian cancer cells is essential for further exploring its therapeutic potential against ovarian cancer.

Methods

The cytotoxic effects of BT against a panel of ovarian cancer cell lines were determined by Presto Blue cell viability assay. Markers of apoptosis such as caspases 3/7, cPARP induction, nuclear condensation and mitochondrial transmembrane depolarization were assessed using microscopic, FACS and immunoblotting methods. Mechanism(s) of action of BT such as cell cycle arrest, reactive oxygen species (ROS) generation, autotaxin (ATX) inhibition and effects on MAPK and NF-kB signalling were determined by FACS analysis, immunoblotting and colorimetric methods.

Results

BT caused dose dependent cytotoxicity against all ovarian cancer cell lines tested with IC₅₀ values ranging from 19 μM – 60 μM. Cisplatin-resistant variants of A2780 and IGROV-1 have shown almost similar IC₅₀ values compared to their sensitive counterparts. Apoptotic cell death was shown by expression of caspases 3/7, cPARP, loss of mitochondrial potential, nuclear condensation, and up-regulation of p38 and reduced expression of pAkt, pNF-κB, pIκBα, XIAP, bcl-2 and bcl-xl. BT treatment resulted in cell cycle arrest at G1/M phase and increased ROS generation. Treatment with ascorbic acid resulted in partial restoration of cell viability. In addition, dose and time dependent inhibition of ATX was observed.

Conclusions

BT exhibits cytotoxic effects on various ovarian cancer cell lines regardless of their sensitivities to cisplatin. Cell death appears to be via caspases mediated apoptosis. The mechanisms of action appear to be partly via cell cycle arrest, ROS generation and inhibition of ATX. The present study provides preclinical data suggesting a potential therapeutic role for BT against recurrent ovarian cancer.