Piperidine nitroxide Tempol enhances cisplatin-induced apoptosis in ovarian cancer cells

Antiproliferative and Apoptotic Effects of Tempol, Methotrexate, and Their Combinations on the MCF7 Breast Cancer Cell Line

Breast cancer holds the top position among the cancers occurring in women. Despite the utilization of surgical removal, chemotherapy, and radiation therapy, there is currently no conclusive treatment available to prevent breast cancer. New treatment approaches are being studied since traditional chemotherapeutics also damage healthy cells. Tempol (TPL) is a potent antioxidant agent that has been shown to exhibit anticancer activity. The objective of this research was to examine the impacts on cell proliferation and apoptosis by using methotrexate (MTX) and TPL individually and in combination on MCF7 breast cancer cells. MCF7 cells were exposed to TPL, MTX, and MTX + TPL for 48 h. The effects of the administered drugs on cell viability were determined using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Enzyme-linked immunosorbent assay analysis was conducted to assess the levels of the antiapoptotic protein Bcl-2, the pro-apoptotic protein Bax, and the activity of caspase-3 in MCF7 cells. Increasing concentrations of TPL and MTX significantly decreased the proliferation in MCF7 cells in both solo and combined use. Solo and combined use of TPL and MTX significantly increased caspase-3 activity and Bax levels and significantly decreased Bcl-2 levels in the cells. This study revealed that the solo use of TPL and MTX inhibited proliferation and increased apoptotic activity in the cells. In addition, TPL increased the antiproliferative and apoptosis efficiency of MTX on cancer cells as a result of the combined use of these drugs.

The anticancer and anti-inflammatory activity screening of pyridazinone-based analogs against human epidermoid skin cancer with detailed mechanistic analyses

3(2H)-Pyridazinone derivatives based on 4-biphenyl, naphtha-2-yl, pyridine, or piperidine moiety were synthesized and characterized using I-R and 1HNMR spectra. The activity and cytotoxicity of some synthesized compounds on the skin epidermoid cancer cell proliferation and progression were investigated. The pyridazine isomer with pyridine revealed a significant decrease in the level of nitric oxide p < 0.01 than the activity of caffeine phenecyl ester. The activity of the three active isomers recorded significant activity for their total antioxidant content that triggers their ability for the scavenging the oxygen free radicals significantly p < 0.01. Moreover, revealing the pharmaceutical activity of the isomers as anti-inflammatory agents, IL-6, IL10, and IL12 have been decreased by variable significant values. Additionally, the active isomers revealed variable actions on the skin cancer cell to induce apoptosis using annexin V-FITC/PI. Pyridine was the highest isomer to induce late apoptosis and necrosis for the skin cancer cells against the use of cisplatin. Importantly, Molecular modeling experiments including docking and dynamic simulations were done for the most active 3 analogs to explore the ligand binding and stability leading to exploring the structure-activity relationship with biological target PARP1 which showed a good binding propensity to pyridazine binding site which supports the in vitro data. In conclusion, the pyridazine moieties with piperdine, naphthayl, and pyridine have pharmacological activities against skin cancer epidermoid by triggering action in inhibition of the proliferation and progression with an up-regulated apoptotic mechanism that evades the emergence of cisplatin resistance among different cancer cells.Communicated by Ramaswamy H. Sarma.

Membrane Partitioning of TEMPO Discriminates Human Lung Cancer from Neighboring Normal Cells

The plasma membranes of normal and cancer cells of the lung, breast, and colon tissues show considerably different lipid compositions that greatly influence their physicochemical properties. Partitioning of the spin probe 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) into the membranes of human lung normal and carcinoma cells was assessed by EPR spectroscopy to estimate the impact of the lipid compositions. The goal was to reveal potential strategies for cancer therapy attributable to the membrane properties. The study was conducted at pH values of 7.3 and 6.2, relevant to the microenvironments of normal and cancer cells, respectively. The TEMPO partitioning was examined in the temperature interval of 283-317K to reveal the efficacy of local hyperthermia used in chemotherapy. Results indicate that the TEMPO partitioning coefficient for the membranes of human lung carcinoma cells is significantly higher compared with that of neighboring normal cells. Increased partition coefficients were observed at relatively higher temperatures in both normal and cancer cells. However, compared to the normal cells, the cancer cells demonstrated higher partition coefficients in the studied temperature range. The data obtained with C12SL (spin-labeled analog of lauric acid) indicate that increased membrane dynamics of the cancer cells is a possible mechanism for enhanced partitioning of TEMPO. Free energy values for partitioning estimated for pH values of 6.2 and 7.3 show that TEMPO partitioning requires 30% less energy in the cancer cells at pH 7.3. TEMPO and its derivatives have previously been considered as theranostic agents in cancer research. Data suggest that TEMPO derivatives could be used to test if complementary alkalization therapy is effective for cancer patients receiving standard chemotherapy with local hyperthermia.

Research Trend and Detailed Insights into the Molecular Mechanisms of Food Bioactive Compounds against Cancer: A Comprehensive Review with Special Emphasis on Probiotics

In an attempt to find a potential cure for cancer, scientists have been probing the efficacy of the food we eat and its bioactive components. Over the decades, there has been an exponentially increasing trend of research correlating food and cancer. This review explains the molecular mechanisms by which bioactive food components exhibit anticancer effects in several cancer models. These bioactive compounds are mainly plant based or microbiome based. While plants remain the primary source of these phytochemicals, little is known about probiotics, i.e., microbiome sources, and their relationships with cancer. Thus, the molecular mechanisms underlying the anticancer effect of probiotics are discussed in this review. The principal mode of cell death for most food bioactives is found to be apoptosis. Principal oncogenic signaling axes such as Akt/PI3K, JAK/STAT, and NF-κB seem to be modulated due to these bioactives along with certain novel targets that provide a platform for further oncogenic research. It has been observed that probiotics have an immunomodulatory effect leading to their chemopreventive actions. Various foods exhibit better efficacy as complete extracts than their individual phytochemicals, indicating an orchestrated effect of the food components. Combining bioactive agents with available chemotherapies helps synergize the anticancer action of both to overcome drug resistance. Novel techniques to deliver bioactive agents enhance their therapeutic response. Such combinations and novel approaches are also discussed in this review. Notably, most of the food components that have been studied for cancer have shown their efficacy in vivo. This bolsters the claims of these studies and, thus, provides us with hope of discovering anticancer agents in the food that we eat.

Tempol Inhibits the Growth of Lung Cancer and Normal Cells through Apoptosis Accompanied by Increased O2•- Levels and Glutathione Depletion

Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl) is a stable, cell-permeable redox-cycling nitroxide water-soluble superoxide dismutase (SOD) mimetic agent. However, little is known about its cytotoxic effects on lung-related cells. Thus, the present study investigated the effects of Tempol on cell growth and death as well as changes in reactive oxygen species (ROS) and glutathione (GSH) levels in Calu-6 and A549 lung cancer cells, normal lung WI-38 VA-13 cells, and primary pulmonary fibroblast cells. Results showed that Tempol (0.5~4 mM) dose-dependently inhibited the growth of lung cancer and normal cells with an IC50 of approximately 1~2 mM at 48 h. Tempol induced apoptosis in lung cells with loss of mitochondrial membrane potential (MMP; ∆Ψm) and activation of caspase-3. There was no significant difference in susceptibility to Tempol between lung cancer and normal cells. Z-VAD, a pan-caspase inhibitor, significantly decreased the number of annexin V-positive cells in Tempol-treated Calu-6, A549, and WI-38 VA-13 cells. A 2 mM concentration of Tempol increased ROS levels, including O2•- in A549 and WI-38 VA-13 cells after 48 h, and specifically increased O2•- levels in Calu-6 cells. In addition, Tempol increased the number of GSH-depleted cells in Calu-6, A549, and WI-38 VA-13 cells at 48 h. Z-VAD partially downregulated O2•- levels and GSH depletion in Tempol-treated these cells. In conclusion, treatment with Tempol inhibited the growth of both lung cancer and normal cells via apoptosis and/or necrosis, which was correlated with increased O2•- levels and GSH depletion.

Anticancer Applications and Pharmacological Properties of Piperidine and Piperine: A Comprehensive Review on Molecular Mechanisms and Therapeutic Perspectives

Piperine and piperidine are the two major alkaloids extracted from black pepper (Piper nigrum); piperidine is a heterocyclic moiety that has the molecular formula (CH₂)₅NH. Over the years, many therapeutic properties including anticancer potential of these two compounds have been observed. Piperine has therapeutic potential against cancers such as breast cancer, ovarian cancer, gastric cancer, gliomal cancer, lung cancer, oral squamous, chronic pancreatitis, prostate cancer, rectal cancer, cervical cancer, and leukemia. Whereas, piperidine acts as a potential clinical agent against cancers, such as breast cancer, prostate cancer, colon cancer, lung cancer, and ovarian cancer, when treated alone or in combination with some novel drugs. Several crucial signalling pathways essential for the establishment of cancers such as STAT-3, NF-κB, PI3k/Aκt, JNK/p38-MAPK, TGF-ß/SMAD, Smac/DIABLO, p-IκB etc., are regulated by these two phytochemicals. Both of these phytochemicals lead to inhibition of cell migration and help in cell cycle arrest to inhibit survivability of cancer cells. The current review highlights the pharmaceutical relevance of both piperine and piperidine against different types of cancers.

Tempol differently affects cellular redox changes and antioxidant enzymes in various lung-related cells

Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl) is a potential redox agent in cells. The present study investigated changes in cellular reactive oxygen species (ROS) and glutathione (GSH) levels and in antioxidant enzymes, in Tempol-treated Calu-6 and A549 lung cancer cells, normal lung WI-38 VA-13 cells, and primary pulmonary fibroblasts. Results demonstrated that Tempol (0.5–4 mM) either increased or decreased general ROS levels in lung cancer and normal cells at 48 h and specifically increased O₂^•− levels in these cells. In addition, Tempol differentially altered the expression and activity of antioxidant enzymes such as superoxide dismutase, catalase, and thioredoxin reductase1 (TrxR1) in A549, Calu-6, and WI-38 VA-13 cells. In particular, Tempol treatment increased TrxR1 protein levels in these cells. Tempol at 1 mM inhibited the growth of lung cancer and normal cells by about 50% at 48 h but also significantly induced cell death, as evidenced by annexin V-positive cells. Furthermore, down-regulation of TrxR1 by siRNA had some effect on ROS levels as well as cell growth inhibition and death in Tempol-treated or -untreated lung cells. In addition, some doses of Tempol significantly increased the numbers of GSH-depleted cells in both cancer cells and normal cells at 48 h. In conclusion, Tempol differentially increased or decreased levels of ROS and various antioxidant enzymes in lung cancer and normal cells, and induced growth inhibition and death in all lung cells along with an increase in O₂^•− levels and GSH depletion.

Beneficial Effect of Tempol, a Membrane-Permeable Radical Scavenger, on Inflammation and Osteoarthritis in In Vitro Models

Osteoarthritis (OA) is one of the most common and widespread diseases which is highly disabling for humans. This makes OA a chronic disease for which it is urgent to find new therapeutic strategies. The inflammatory state in OA contributes to its progression through multiple mechanisms involving the recruitment of phagocytes and leukocytes, inflammatory response, and reactive oxygen species (ROS) production. Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl) is classifiable as a piperidine nitroxide, with excellent antioxidant effects, while its anti-inflammatory role is not yet clear. On this basis, we explored its promising biological properties in two in vitro model:, macrophage (J774) and chondrocyte (CC) cell lines. With this aim in mind, we induced inflammation in J774 and CC using lipopolysaccharide (LPS) and Interleukin1β (IL-1β), and after 24, 72 and 168 h of tempol treatment analyzed their effects on cytotoxicity and anti-inflammatory activity. Our data suggested that tempol treatment is able to reduce inflammation and nitrite production in LPS-induced J774 as well as reducing the production of proinflammatory mediators including cytokines, enzymes, and metalloproteases (MMPs) in IL-1β-stimulated CC. Thus, since inflammation and oxidative stress have a crucial role in the pathogenesis and progression of OA, tempol could be considered as a new therapeutic approach for this pathology.

Knockdown of TRAP1 promotes cisplatin-induced apoptosis by promoting the ROS-dependent mitochondrial dysfunction in lung cancer cells

The tumor necrosis factor receptor-associated protein 1 (TRAP1) is associated with the occurrence and development of various diseases, including inflammation and cancer. However, the role and mechanism of TRAP1 in the development of lung cancer need to be further explored. Therefore, the purpose of this study is to investigate the role of TRAP1 in the regulation of apoptosis by cisplatin and its special mechanism. The RT-qPCR and Western blot were used to detect the mRNA and protein expression of ANGPTL4 in A549 and H1299 cells, respectively. And the cell apoptosis and cell cycle were measured by flow cytometry (FCM). The expression of genes related to apoptosis and drug resistance as well as the cell cycle regulators, including MDM2, CyclinB1, and CDK1, were detected by Western blot. Finally, the reactive oxygen species (ROS) indicator DCFH-DA was performed to detect the generation of ROS, and the mitochondrial membrane potential (ΔΨm) was detected by JC-1 staining. The results showed that the expression of TRAP1 was significantly increased in A549/DDP and H1299/DDP than A549 and H1299 cells. Further research found that knockdown of TRAP1 induced apoptosis and caused G2/M cell cycle arrest in A549/DDP and H1299/DDP cells. What is more, siTRAP1 reduced the relative JC-1 polymer monomer fluorescence ratio and decreased the ΔΨm, up-regulated the expression of Cytochrome C. Importantly, siTRAP1 induces ROS-dependent mitochondrial dysfunction. It is suggested that that TRAP1 suppresses cisplatin-induced apoptosis by promoting ROS-dependent mitochondrial dysfunction.