drug-induced-senescence-liver-cells-promotes-m2-macrophage

Drug-Induced Senescence in Liver Cells Promotes M2 Macrophage Polarization: Implications for Tyrosine Kinase Inhibitor-Associated Hepatotoxicity

Lapatinib and neratinib are tyrosine kinase inhibitors (TKIs) approved for treating HER2-positive metastatic breast cancer, but their clinical use is ...

Shiv Nadar Institution of Eminence

Survivin is a lucrative broad-spectrum drug target for different cancer types, including triple negative breast cancer (TNBC). Sepantronium bromide (YM155) is the first of its class of survivin suppressants and was found to be quite effective in pre-clinical models of TNBC. However, in clinical trials when given in combination with docetaxel, YM55 failed to provide any added advantage. To understand if the clinical outcome is due to YM155 being ineffective or due to an inappropriate choice of combination, we need to elucidate its true mode of action. Hence, to explain the unexpected and unexplained observations pertaining to YM155 biology and its mode of action, we developed isogenic pairs of YM155-sensitive and -resistant TNBC cell lines and characterized them in detail by various biochemical assays. We found that YM155 generates reactive oxygen species (ROS) in the mitochondria in addition to the previously discovered redox cycling pathway. Both survivin suppression and DNA damage are secondary effects resulting from the ROS which contribute to the drug's cytotoxic effects on TNBC cells. Indeed, adaptation to both these pathways was important in conferring YM155 resistance. Finally, we uncovered a unique connection between the ROS and control of survivin expression involving a ROS/AKT/FoxO/survivin axis in TNBC cells. Together, by deciphering the true mode of action of YM155, we present a possible explanation for its poor clinical efficacy when used in combination with docetaxel. The results and conclusions presented here provide the information needed to effectively use YM155 in combination therapy.

Generation of reactive oxygen species is the primary mode of action and cause of survivin suppression by sepantronium bromide (YM155).

Editorial: Tumor adaptation to cellular stresses: mechanisms, biomarkers and therapeutic opportunities.

The oxidation-reduction reactions of disulfides are important in both chemistry and biology. Dimethyl disulfide (DMDS), the smallest reduced sulfur species with a disulfide bond, is emitted in significant quantities from natural sources and contributes to the formation of aerosols and hazardous haze. Although atmospheric removal of DMDS via the reactions with OH or NO radicals and photolysis is known, the reactions of DMDS with other atmospheric oxidants are yet to be explored. Herein, using quantum chemical calculations, we explored the reactions of DMDS with CHOO (formaldehyde oxide) and other methyl-substituted Criegee intermediates. The various reaction pathways evaluated were found to have positive energy barriers. However, in the presence of formic acid, a direct oxygen-transfer pathway leading to the corresponding sulfoxide (CHSS(O)CH) was found to proceed through a submerged transition state below the separated reactants. Calculations for the methyl-substituted Criegee intermediates, particularly for -CHCHOO, show a significant increase in the rate of the direct oxygen-transfer reaction when catalyzed by formic acid. The presence of formic acid also alters the mechanism and reduces the enthalpic barrier of a second pathway, forming thioformaldehyde and hydroperoxide without any rate enhancement. Our data indicated that, although Criegee intermediates are unlikely to be an important atmospheric sink of DMDS under normal conditions, in regions rich in DMDS and formic acid, the formic acid-catalyzed Criegee intermediate-mediated oxidation of DMDS via the direct oxygen-transfer pathway could lead to organic sulfur compounds contributing to atmospheric aerosol.

Criegee Intermediate-Mediated Oxidation of Dimethyl Disulfide: Effect of Formic Acid and Its Atmospheric Relevance.

Cancers frequently have increased ROS levels due to disrupted redox balance, leading to oxidative DNA and protein damage, mutations, and apoptosis. The MTH1 protein plays a crucial role by sanitizing the oxidized dNTP pools. Hence, cancer cells rely on MTH1 to prevent the integration of oxidized dNTPs into DNA, preventing DNA damage and allowing cancer cell proliferation. We have discovered Thymoquinone (TQ) and Baicalin (BC) as inhibitors of MTH1 using combined docking and MD simulation approaches complemented by experimental validations via assessing binding affinity and enzyme inhibition. Docking and MD simulations studies revealed an efficient binding of TQ and BC to the active site pocket of the MTH1, and the resultant complexes are appreciably stable. Fluorescence measurements estimated a strong binding affinity of TQ and BC with Ka 3.4 ×10 and 1.0 ×10, respectively. Treating breast cancer cells with TQ and BC significantly inhibited the growth and proliferation (IC values 28.3 µM and 34.8 µM) and induced apoptosis. TQ and BC increased the ROS production in MCF7 cells, imposing substantial oxidative stress on cancer cells and leading to cell death. Finally, TQ and BC are proven strong MTH1 inhibitors, offering promising prospects for anti-cancer therapy.

Exploring MTH1 inhibitory potential of Thymoquinone and Baicalin for therapeutic targeting of breast cancer.

Editorial: Resistance to endocrine therapies in cancer, volume II.

Survivin, a cancer-cell-specific multifunctional protein, is regulated by many oncogenic signaling pathways and an effective therapeutic target. Although, several types of survivin-targeting agents have been developed over the past few decades, none of them received clinical approval. This could be because survivin expression is tightly controlled by the feedback interaction between different signaling molecules. Of the several signaling pathways that are known to regulate survivin expression, the phosphatidylinositol 3-kinase/AKT serine-threonine kinase/forkhead boxO (PI3K/AKT/FoxO) pathway is well-known for feedback loops constructed by cross-talk among different molecules. Using sepantronium bromide (YM155), the first of its class of survivin-suppressant, we uncovered the existence of an interesting cross-talk between Nuclear Factor Erythroid 2-Related Factor 2 (NRF2) and FoxO transcription factors that also contributes to YM155 resistance in triple negative breast cancer (TNBC) cells. Pharmacological manipulation to interrupt this interaction not only helped restore/enhance the drug-sensitivity but also prompted effective immune clearance of cancer cells. Because the YM155-induced reactive oxygen species (ROS) initiates this feedback, we believe that it will be occurring for many ROS-producing chemotherapeutic agents. Our work provides a rational explanation for the poor efficacy of YM155 compared to standard chemotherapy in clinical trials. Finally, the triple drug combination approach used herein might help reintroducing YM155 into the clinical pipeline, and given the high survivin expression in TNBC cells in general, it could be effective in treating this subtype of breast cancer.

Sphingosine-1-phosphate (S1P) formed via catalytic actions of sphingosine kinase 1 (SphK1) behaves as a pro-survival substance and activates downstream target molecules associated with various pathologies, including initiation, inflammation, and progression of cancer. Here, we aimed to investigate the SphK1 inhibitory potentials of thymoquinone (TQ), Artemisinin (AR), and Thymol (TM) for the therapeutic management of lung cancer. We implemented docking, molecular dynamics (MD) simulations, enzyme inhibition assay, and fluorescence measurement studies to estimate binding affinity and SphK1 inhibitory potential of TQ, AR, and TM. We further investigated the anti-cancer potential of these compounds on non-small cell lung cancer (NSCLC) cell lines (H1299 and A549), followed by estimation of mitochondrial ROS, mitochondrial membrane potential depolarization, and cleavage of DNA by comet assay. Enzyme activity and fluorescence binding studies suggest that TQ, AR, and TM significantly inhibit the activity of SphK1 with IC values of 35.52 µM, 42.81 µM, and 53.68 µM, respectively, and have an excellent binding affinity. TQ shows cytotoxic effect and anti-proliferative potentials on H1299 and A549 with an IC value of 27.96 µM and 54.43 µM, respectively. Detection of mitochondrial ROS and mitochondrial membrane potential depolarization shows promising TQ-induced oxidative stress on H1299 and A549 cell lines. Comet assay shows promising TQ-induced oxidative DNA damage. In conclusion, TQ, AR, and TM act as potential inhibitors for SphK1, with a strong binding affinity. In addition, the cytotoxicity of TQ is linked to oxidative stress due to mitochondrial ROS generation. Overall, our study suggests that TQ is a promising inhibitor of SphK1 targeting lung cancer therapy.

Thymoquinone, artemisinin, and thymol attenuate proliferation of lung cancer cells as Sphingosine kinase 1 inhibitors.

PIM-1 kinase belongs to the Ser/Thr kinases family, an attractive therapeutic target for prostate cancer. Here, we screened about 100 natural substances to find potential PIM-1 inhibitors. Two natural compounds, Naringenin and Quercetin, were finally selected based on their PIM-1 inhibitory potential and binding affinities. The docking score of Naringenin and Quercetin with PIM-1 is -8.4 and - 8.1 kcal/mol, respectively. Fluorescence binding studies revealed a strong affinity (Ka values, 3.1 × 10 M and 4.6 × 10 M for Naringenin and Quercetin, respectively) with excellent IC values for Naringenin and Quercetin (28.6 μM and 34.9 μM, respectively). Both compounds inhibited the growth of prostate cancer cells (LNCaP) in a dose-dependent manner, with the IC value of Naringenin at 17.5 μM and Quercetin at 8.88 μM. To obtain deeper insights into the PIM-1 inhibitory effect of Naringenin and Quercetin, we performed extensive molecular dynamics simulation studies, which provided insights into the binding mechanisms of PIM-1 inhibitors. Finally, Naringenin and Quercetin were suggested to serve as potent PIM-1 inhibitors, offering targeted treatments of prostate cancer. In addition, our findings may help to design novel Naringenin and Quercetin derivatives that could be effective in therapeutic targeting of prostate cancer.

Targeting prostate cancer via therapeutic targeting of PIM-1 kinase by Naringenin and Quercetin.

Inflammation is an early immune response against invading pathogens and damaged tissue. Although beneficial, uncontrolled inflammation leads to various diseases including cancer in a chronic setting. Peroxynitrite (PN) is a major reactive nitrogen species generated during inflammation. It produces various DNA lesions including 8-nitro-guanine which spontaneously converts into abasic sites, resulting in DNA strand breakage, and is suspected to be mutagenic. Here, we report the discovery of a previously unrecognized function of the human repair protein -alkylguanine-DNA alkyltransferase (hAGT or MGMT). We showed that hAGT through its active site nucleophilic Cys145 thiolate spontaneously reacts with 8-nitro-guanine in DNA to form a stable DNA-protein cross-link (DPC). Interestingly, the process of DPC formation provided protection from PN-mediated genome instability, growth arrest, and apoptosis. The Cys145 mutant of hAGT failed to form a DPC and was unable to protect cells from inflammation-associated PN-mediated cytotoxicity. Gel-shift, dot blot, and UV-vis assays showed formation of a covalent linkage between PN-damaged DNA and hAGT through its active site Cys145. Finally, expression of hAGT was found to be significantly increased by induced macrophages and PN. The data presented here clearly demonstrated hAGT as a dual-function protein that along with DNA repair is capable of maintaining genomic integrity and providing protection from the toxicity caused by PN-mediated DNA damage. Although DPCs are known to be detrimental to the cell, recently, multiple pathways have been identified in normal cells for their repair.

-Alkylguanine-DNA Alkyltransferase Maintains Genome Integrity by Forming DNA-Protein Cross-Links during Inflammation-Associated Peroxynitrite-Mediated DNA Damage.

The increased metabolic activity in cancer cells often leads to higher levels of reactive oxygen species compared to normal cells, which can cause damage to cellular components, including DNA. Cancer cells rely on MTH1 to maintain their DNA integrity and cellular function to counteract this damage. MTH1 is critical in sanitizing oxidized nucleotide pools by removing damaged nucleotides. Inhibition of MTH1 disrupts this repair process, leading to increased DNA damage and cell death in cancer cells. In this study, we present resveratrol (RV) as a potential MTH1 inhibitor. Docking and MD Simulations illustrated the effective binding of RV to the active site of the MTH1 protein, forming a notably stable complex. The fluorescence binding studies estimated a high binding affinity of RV with MTH1 (K 6.2 × 10M, inhibiting MTH1 activity with IC 18.13 ± 1.08 µM. The inhibitory effects of RV on the proliferation of breast cancer cells (MCF-7) revealed significant inhibition in cell growth, leading to apoptosis. RV significantly increases ROS production, inducing considerable oxidative stress and ultimately resulting in cell death. Our study offers a rationale for evaluating RV as an MTH1 inhibitor for potential anti-cancer therapy, particularly in breast cancer.

Article	Year
Generation of reactive oxygen species is the primary mode of action and cause of survivin suppression by sepantronium bromide (YM155). RSC medicinal chemistry\| PubMed ID: 34046628	2021
Editorial: Tumor adaptation to cellular stresses: mechanisms, biomarkers and therapeutic opportunities. Frontiers in medicine\| PubMed ID: 37663659	2023
Criegee Intermediate-Mediated Oxidation of Dimethyl Disulfide: Effect of Formic Acid and Its Atmospheric Relevance. The journal of physical chemistry. A\| PubMed ID: 37782474	2023
Exploring MTH1 inhibitory potential of Thymoquinone and Baicalin for therapeutic targeting of breast cancer. Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie\| PubMed ID: 38430630	2024
Editorial: Resistance to endocrine therapies in cancer, volume II. Frontiers in endocrinology\| PubMed ID: 38715800	2024
. ACS pharmacology & translational science\| PubMed ID: 38751638	2024
Thymoquinone, artemisinin, and thymol attenuate proliferation of lung cancer cells as Sphingosine kinase 1 inhibitors. Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie\| PubMed ID: 39004062	2024
Targeting prostate cancer via therapeutic targeting of PIM-1 kinase by Naringenin and Quercetin. International journal of biological macromolecules\| PubMed ID: 39019373	2024
-Alkylguanine-DNA Alkyltransferase Maintains Genome Integrity by Forming DNA-Protein Cross-Links during Inflammation-Associated Peroxynitrite-Mediated DNA Damage. Chemical research in toxicology\| PubMed ID: 39431584	2024
Repurposing resveratrol for redox-mediated inhibition of MTH1 in breast cancer. Scientific reports\| PubMed ID: 41023007	2025

Anindita Chakrabarty

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