Induction Of Apoptotic Genes Research Articles

Abstract 5756: Silver graphene quantum dots as drug delivery platforms for anti-cancer application

Abstract Prostate cancer (PCa) stands as the most frequently diagnosed cancer and the third leading cause of cancer-related deaths among men in the United States (2019). Various cancer treatments, including Rehabilitation therapy, Immunotherapy, Hormone therapy, Stem Cell Therapy, and Chemotherapy, are available. However, chemotherapy has notable limitations due to its tendency to harm healthy cells, resulting in side effects such as nausea, vomiting, alopecia, diarrhea, anemia, bleeding, and sterility. In response to these challenges, we developed nanoparticle (NP) drug delivery platforms for cancer treatment. These platforms utilize silver graphene quantum dots nanocomposites (AgGQD), known for their ability to enhance drug therapies. Silver nanoparticles (AgNPs) exhibit toxicity towards both normal and cancer cells by impacting mitochondrial function, reactive oxygen species (ROS) production, lactate dehydrogenase (LDH) release, cell cycle dysregulation, induction of apoptotic genes like Bax, micronucleus formation, chromosome aberration, and DNA damage. Additionally, AgNPs demonstrate antiangiogenic and antiproliferative properties by inhibiting PI3K phosphorylation of Akt, disrupting the signaling pathway, ultimately halting angiogenesis, depriving cells of oxygen, and causing tumor cell death. To mitigate the toxicity of AgNPs in healthy cells and enhance their performance as drug delivery platforms, graphene quantum dots (GQDs) were introduced in this study. Moreover, GQDs may contribute to improving the solubility of drugs with low water solubility. The NPs were synthesized using graphene quantum dots as reducing agents. The study involved identifying the IC50 value, conducting validation tests on AgGQD and AgGQD doped, and comparing their toxicity on cells. Confocal microscopy was employed to identify the intracellular location of the drug. Citation Format: Rafael A. Villanueva, Tori Cole, Nataniel Medina, Dr. Gerardo Morell, Brad Weiner. Silver graphene quantum dots as drug delivery platforms for anti-cancer application [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5756.

Genotoxic and Cytotoxic Activities of Lantadene A-Loaded Gold Nanoparticles (LA-AuNPS) in MCF-7 Cell Line: An in vitro Assessment.

Gold nanoparticles (AuNPs) have been widely used in many applications. Their usage as drug delivery vehicles has also gained considerable attention due to their chemical and optical properties as well as their good biocompatibility. The present study was conducted to evaluate the efficiency of AuNPs in enhancing the cytotoxic and apoptotic induction activity of lantadene A (LA), separated from Lantana camara leaves, on the breast tumor cell line MCF-7 in vitro. By utilizing plant-mediated synthesis method of nanostructures, LA-loaded AuNPs (LA-AuNPs) were prepared and their formation was confirmed by means of ultraviolet-visible spectroscope, atomic force microscope, scanning electron microscope, and zeta potential. The cytotoxic effect of LA-AuNPs was analyzed using a methylthiazol tetrazolium assay and compared to free AuNPs and LA. The results indicated a significant increase in the reduction of MCF-7 cells viability after incubation with LA-AuNPs. As determined by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, LA-AuNPs induced a greater ratio of DNA-fragmented cells compared to LA-treated and untreated cells. Also, by operating real-time polymerase chain reaction, LA-AuNPs-treated cells displayed an increased upregulation of p53 expression and downregulation of BCL-2 expression in addition to a significant reduction in the level of BCL-2-BAX ratio. No significant effect was shown on the expression of BAX. Collectively, our results indicate that LA-AuNPs showed promising cytotoxicity to MCF-7 cells as a novel nanoscale preparation, likely via induction of apoptotic genes and stimulation of DNA fragmentation.

Abstract 220: SR4 uncouples mitochondrial oxidative-phosphorylation, modulates AMPK-mTOR signaling, and inhibits proliferation of HepG2 hepatocarcinoma cells

Abstract Mitochondrial oxidative phosphorylation produces most of the energy in aerobic cells by coupling respiration with the production of ATP. Mitochondrial uncouplers, which reduce the proton gradient across the mitochondrial inner membrane, create a futile cycle of nutrient oxidation without generating ATP. Regulation of mitochondrial dysfunction and associated cellular bioenergetics has been recently identified as promising targets for anticancer therapy. Here, we show that SR4 is a novel mitochondrial uncoupler that causes dose-dependent increase in mitochondrial respiration and dissipation of mitochondrial membrane potential (MMP) in HepG2 hepatocarcinoma cells. These effects were reversed by the recoupling agent 6-ketocholestanol, but not cyclosporin A, and were non-existent in mitochondria-DNA depleted HepG2 (po) cells. In isolated mouse liver mitochondria, SR4 similarly increased oxygen consumption independent of adenine nucleotide translocase (ANT) and uncoupling proteins, decreases MMP, and promotes swelling of valinomycin-treated mitochondria in potassium acetate media. Mitochondrial uncoupling in HepG2 cells by SR4 results in the reduction of cellular ATP production, increased ROS production, activation of the energy-sensing enzyme AMPK, and inhibition of acetyl-CoA carboxylase and mammalian target of rapamycin (mTOR) signaling pathways, leading to cell cycle arrest and apoptosis. Global analysis of SR4-associated differential gene expression confirms these observations, including significant induction of apoptotic genes and down regulation of cell cycle, mitochondrial and oxidative-phosphorylation pathway transcripts at 24 h post treatment. Collectively, our studies demonstrate that SR4's previously reported indirect activation of AMPK and in-vitro anticancer properties, as well as its beneficial effects in both animal xenograft and obese mice models could be a direct consequence of its mitochondrial uncoupling activity (Supported by NIH grant CA 77495 and Beckman Research Institute of the City of Hope). Citation Format: Sharad S. Singhal, James Figarola, Jyotsana Singhal, Joshua Tompkins, David Horne, Sanjay Awasthi, Arthur Riggs. SR4 uncouples mitochondrial oxidative-phosphorylation, modulates AMPK-mTOR signaling, and inhibits proliferation of HepG2 hepatocarcinoma cells. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 220.

Knockout ofDrosophilaRNase ZLimpairs mitochondrial transcript processing, respiration and cell cycle progression

RNase ZL is a highly conserved tRNA 3′-end processing endoribonuclease. Similar to its mammalian counterpart, Drosophila RNase ZL (dRNaseZ) has a mitochondria targeting signal (MTS) flanked by two methionines at the N-terminus. Alternative translation initiation yields two protein forms: the long one is mitochondrial, and the short one may localize in the nucleus or cytosol. Here, we have generated a mitochondria specific knockout of the dRNaseZ gene. In this in vivo model, cells deprived of dRNaseZ activity display impaired mitochondrial polycistronic transcript processing, increased reactive oxygen species (ROS) and a switch to aerobic glycolysis compensating for cellular ATP. Damaged mitochondria impose a cell cycle delay at the G2 phase disrupting cell proliferation without affecting cell viability. Antioxidants attenuate genotoxic stress and rescue cell proliferation, implying a critical role for ROS. We suggest that under a low-stress condition, ROS activate tumor suppressor p53, which modulates cell cycle progression and promotes cell survival. Transcriptional profiling of p53 targets confirms upregulation of antioxidant and cycB-Cdk1 inhibitor genes without induction of apoptotic genes. This study implicates Drosophila RNase ZL in a novel retrograde signaling pathway initiated by the damage in mitochondria and manifested in a cell cycle delay before the mitotic entry.

Abstract 4780: Nucleosome organization and accessibility of p53 response elements in the chromatin context

Abstract p53 is one of best known human proteins that induces or represses hundreds of genes and plays a pivotal role in preventing tumor development. Recent studies established unambiguously that p53 is a nucleosome-binding protein. The rotational positioning of a nucleosome is critical to determine the accessibility of a p53 site. In particular, the p53 site in a nucleosome is accessible if it is bent in the direction similar to that found in the p53-DNA co-crystals; the site becomes inaccessible if the orientation is changed by ∼180°. Importantly, we have shown that p53 response elements (REs) associated with cell cycle arrest are often exposed on the nucleosomal surface, suggesting a new role of nucleosomes in mediating the p53 binding and subsequent gene induction. The present study aims to make a detailed analysis of nucleosome organization of all p53 functional REs in normal and cancer cells. Published genome-wide nucleosome maps from lymphoblastoid (normal) and K562 (cancer) cell lines are used. In general, the p53 REs are located in nucleosome-enriched regions, in accordance with previous findings that p53 can interact with nucleosomal DNA. At the level of individual sites, the p21 5′ RE resides in a genomic region with high nucleosome occupancy, consistent with earlier studies. The GADD45 RE that was believed to be in nucleosome-free region, is, however, characterized with medium-to-high nucleosome occupancy. To evaluate the accessibility of p53 REs in different functional groups such as cell cycle arrest, apoptosis and DNA repair, we used a more rigorous set of nucleosomes, containing 134 million 147-bp fragments (about 7x genome coverage). The REs in the cell cycle arrest group (such as p21) and the DNA repair group (such as GADD45) are often accessible in the chromatin context, consistent with fast induction of these genes after p53 activation. Interestingly, apoptotic REs are divided - the REs associated with the mitochondrial pathway (BAX and p53AIP1) are accessible, while the REs associated with the death receptor pathway (FAS and KILLER) are inaccessible, suggesting different mechanisms for induction of apoptotic genes in vivo. Finally, we observe a clear correlation between the nucleosome occupancy and accessibility of p53 REs. That is, the REs with the higher nucleosome occupancy tend to be accessible, while the REs with lower nucleosome occupancy are likely to be inaccessible to p53. Citation Format: Peter R. LoVerso, Victor B. Zhurkin, Feng Cui. Nucleosome organization and accessibility of p53 response elements in the chromatin context. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4780. doi:10.1158/1538-7445.AM2015-4780

SAHA/Vorinostat induces the expression of the CD137 receptor/ligand system and enhances apoptosis mediated by soluble CD137 receptor in a human breast cancer cell line

HDAC inhibitors (HDACis) represent a class of anticancer agents including suberoylanilide hydroxamic acid (SAHA, Vorinostat), which has shown a strong antitumor effect, both in vitro and in vivo. Induction of apoptotic genes is an important pathway of SAHA cytotoxic mechanism of action and it has been largely described that SAHA induces sensitization of cell death receptor-resistant breast cancer cells to apoptosis. In this study, we investigated the activation of some apoptotic genes which could be responsible for the in vivo antitumor potency of SAHA in a model of human breast cancer. We found that the apoptotic gene pattern induced by SAHA in the MDA-MB-231 cell line involves the upregulation of some molecules belonging to the TNF superfamily. In particular, we demonstrated that the upregulation of the CD137 receptor/ligand system correlates with a synergistic cytotoxic effect when MDA-MB-231 cells are treated with the combination of SAHA and soluble CD137 receptor. To our knowledge, this is the first study to indicate that this member of the TNF superfamily, CD137, is modulated by SAHA treatment in breast cancer cells, suggesting that the combination of SAHA with this TNF-related receptor could be a new therapeutic approach for the treatment of tumors.

Induction of Apoptotic Genes by a p73-Phosphatase and Tensin Homolog (p73-PTEN) Protein Complex in Response to Genotoxic Stress

The p53 family member, p73, has been characterized as a tumor suppressor and functions in a similar manner as p53 to induce cellular death. The phosphatase and tensin homolog (PTEN) can function as a dual specificity lipid/protein phosphatase. However, recent data have described multiple roles for nuclear PTEN independent of its lipid phosphatase activity. PTEN can directly or indirectly activate p53 to promote apoptosis. We examined whether PTEN would interact and regulate p73 independent of p53. Co-localization in the nucleus and complex formation of p73/PTEN were observed after DNA damage. Furthermore, we also demonstrate that p73α/PTEN proteins directly bind one another. Both overexpressed and endogenous p73-PTEN interactions were determined to be the strongest in the nuclear fraction after DNA damage, which suggested formation of a transcriptional complex. We employed chromatin immunoprecipitation (ChIP) and found that p73 and PTEN were associated with the PUMA promoter after genotoxic stress in TP53-null cells. We found that another p73 target, BAX, had an increased expression in the presence of p73 and PTEN. In addition, in virus-transduced cell lines stably expressing p73, PTEN, or both p73/PTEN, we found that the p73/PTEN cells were more sensitive to genotoxic stress and cellular death as measured by increased poly(ADP-ribose) polymerase cleavage and PUMA/Bax induction. Conversely, knockdown of PTEN dramatically reduced Bax and PUMA levels. Thus, a p73-PTEN protein complex is engaged to induce apoptosis independent of p53 in response to DNA damage.

IL-12 inhibits glucocorticoid-induced T cell apoptosis by inducing GMEB1 and activating PI3K/Akt pathway

Interleukin (IL)-12 is an important pro-inflammatory cytokine that has been shown to play a role in T cell survival, at least in part by activating the PI3K/Akt pathway. Glucocorticoid modulatory element binding protein (GMEB)1 and 2 are closely related proteins that modify the glucocorticoid receptor binding locus and thus modulate glucocorticoid-mediated gene induction effects, including apoptosis. GMEB1 associates with caspases and prevents apoptosis of cells in the nervous system. We have observed, in preliminary studies, that IL-12 up-regulates GMEB mRNA in human T cells, and postulated that this may contribute to the anti-apoptotic effect of IL-12 on T cells, in particular with regard to glucocorticoid induced apoptosis. Here, we confirm that IL-12 rescue of dexamethasone induced T cell apoptosis involves the PI3K/Akt pathway and that IL-12 induces GMEB1 and GMEB2. A siRNA knockdown of GMEB1 reverses the protective effect of IL-12 on dexamethasone induced T cell apoptosis. Thus, IL-12 protects T cells from glucocorticoid induced apoptosis via PI3K/Akt pathway and via induction of GMEB1, which is likely to reduce transactivation of the glucocorticoid receptor and induction of apoptotic genes. As glucocorticoid induced apoptosis occurs both in physiological and pathological/therapeutic situations, and IL-12 is actively involved in a variety of inflammatory and immune responses, the ability of IL-12 to inhibit steroid responses and increase T cell survival through GMEB1 has wide ranging implications. Manipulating GMEB may be used therapeutically to enhance the resistance or the sensitivity to steroids.

Calcium-dependent apoptotic gene expression in cerulein-treated AR42J cells.

Elevated Ca(2+) concentrations within the pancreatic acinar cells represent a risk factor for the development of acute pancreatitis. Apoptosis is an important characteristic of pancreatitis, with induction of apoptotic genes and intraceullar increase of calcium, endonucleases, and protease. The present study, which aims to investigate whether (1) cerulein induces apoptotic gene expression (bax, bid, p53) in pancreatic acinar AR42J cells and (2) cerulein-induced gene expression is mediated by intracellular Ca(2+), monitored the gene expression profile in the cells treated with the Ca(2+) chelator BAPTA-AM. Results showed that cerulein (10(-7) M) evoked an initial peak Ca(2+) signal; a further Ca(2+) signal was induced with second treatment of cerulein. Cerulein-induced Ca(2+) signal could not be detected in the cells treated with the Ca(2+) chelator BAPTA-AM. Cerulein dose-dependently induced apoptosis, determined by DNA fragmentation and pro-apoptotic bid expression in AR42J cells. Cerulein induced bid, bax, and p53 mRNA expression, which was inhibited in the cells treated with cerulein and cultured in the presence of BAPTA-AM. The present results suggest that increase in the free cytosolic Ca(2+) may be the upstream event of apoptotic gene (bax, bid, p53) expression, which contribute to cerulein-induced apoptosis in pancreatic acinar cells.