p53 activates the CD95 (APO-1/Fas) gene in response to DNA damage by anticancer drugs

The role of programmed cell death in osteosarcoma: From pathogenesis to therapy

Osteosarcoma (OS) is a prevalent bone solid malignancy that primarily affects adolescents, particularly boys aged 14-19. This aggressive form of cancer often leads to deadly lung cancer due to its high migration ability. Experimental evidence suggests that programmed cell death (PCD) plays a crucial role in the development of osteosarcoma. Various forms of PCD, including apoptosis, ferroptosis, autophagy, necroptosis, and pyroptosis, contribute significantly to the progression of osteosarcoma. Additionally, different signaling pathways such as STAT3/c-Myc signal pathway, JNK signl pathway, PI3k/AKT/mTOR signal pathway, WNT/β-catenin signal pathway, and RhoA signal pathway can influence the development of osteosarcoma by regulating PCD in osteosarcoma cell. Therefore, targeting PCD and the associated signaling pathways could offer a promising therapeutic approach for treating osteosarcoma.

Elucidating the chain of command: our current understanding of critical target genes for p53-mediated tumor suppression

TP53 encodes a transcription factor that is centrally-involved in several pathways, including the control of metabolism, the stress response, DNA repair, cell cycle arrest, senescence, programmed cell death, and others. Since the discovery of TP53 as the most frequently-mutated tumor suppressor gene in cancer over four decades ago, the field has focused on uncovering target genes of this transcription factor that are essential for tumor suppression. This search has been fraught with red herrings, however. Dozens of p53 target genes were discovered that had logical roles in tumor suppression, but subsequent data showed that most were not tumor suppressive, and were dispensable for p53-mediated tumor suppression. In this review, we focus on p53 transcriptional targets in two categories: (1) canonical targets like CDKN1A (p21) and BBC3 (PUMA), which clearly play critical roles in p53-mediated cell cycle arrest/senescence and cell death, but which are not mutated in cancer, and for which knockout mice fail to develop spontaneous tumors; and (2) a smaller category of recently-described p53 target genes that are mutated in human cancer, and which appear to be critical for tumor suppression by p53. Interestingly, many of these genes encode proteins that control broad cellular pathways, like splicing and protein degradation, and several of them encode proteins that feed back to regulate p53. These include ZMAT3, GLS2, PADI4, ZBXW7, RFX7, and BTG2. The findings from these studies provide a more complex, but exciting, potential framework for understanding the role of p53 in tumor suppression.

Decoding cell death signalling: Impact on the response of breast cancer cells to approved therapies

Breast cancer is a principal cause of cancer-related mortality in female worldwide. While many approved therapies have shown promising outcomes in treating breast cancer, understanding the intricate signalling pathways controlling cell death is crucial for optimizing the treatment outcome. A growing body of evidence has unveiled the aberrations in multiple cell death pathways across diverse cancer types, highlighting these pathways as appealing targets for therapeutic interventions. In this review, we provide a comprehensive overview of the current state of knowledge on the cell death signalling mechanisms with a particular focus on their impact on the response of breast cancer cells to approved therapies. Additionally, we discuss the potentials of combination therapies that exploit the synergy between approved drugs and therapeutic agents targeting modulators of cell death pathways.

Strong apoptotic response of testis tumor cells following cisplatin treatment

Most solid metastatic cancers are resistant to chemotherapy. However, metastatic testicular germ cell tumors (TGCT) are cured in over 80% of patients using cisplatin-based combination therapy. Published data suggest that TGCTs are sensitive to cisplatin due to limited DNA repair and presumably also to a propensity to undergo apoptosis. To further investigate this aspect, cisplatin-induced activation of apoptotic pathways was investigated in cisplatin-sensitive testis tumor cells (TTC) and compared to cisplatin-resistant bladder cancer cells. Apoptosis induction was investigated using flow cytometry, caspase activation and PARP-1 cleavage. Immunoblotting and RT-PCR were applied to investigate pro- and anti-apoptotic proteins. Transfections were performed to target p53- and Fas/FasL-mediated apoptotic signaling. Immunoblotting experiments revealed p53 to be induced in TTC, but not bladder cancer cells following cisplatin. Higher levels of pro-apoptotic Bax and Noxa were observed in TTC, anti-apoptotic Bcl-2 was solely expressed in bladder cancer cells. Cisplatin led to translocation of Bax to the mitochondrial membrane in TTC, resulting in cytochrome C release. Cisplatin increased the expression of FasR mRNA and FasL protein in all tumor cell lines. Targeting the apoptotic pathway via siRNA-mediated knockdown of p53 and FAS reduced death receptor-mediated apoptosis and increased cisplatin resistance in TTC, indicating the involvement of FAS-mediated apoptosis in the cisplatin TTC response. In conclusion, both the death receptor and the mitochondrial apoptotic pathway become strongly activated in TTC following cisplatin treatment, explaining, together with attenuated DNA repair, their unique sensitivity toward platinum-based anticancer drugs.

Recent advances in CAR T-cell engineering using synthetic biology: Paving the way for next-generation cancer treatment

This book chapter highlights a comprehensive exploration of the transformative innovations in the field of cancer immunotherapy. CAR (Chimeric Antigen Receptor) T-cell therapy represents a groundbreaking approach to treat cancer by reprogramming a patient immune cells to recognize and destroy cancer cells. This chapter underscores the critical role of synthetic biology in enhancing the safety and effectiveness of CAR T-cell therapies. It begins by emphasizing the growing importance of personalized medicine in cancer treatment, emphasizing the shift from one-size-fits-all approaches to patient-specific solutions. Synthetic biology, a multidisciplinary field, has been instrumental in customizing CAR T-cell therapies, allowing for fine-tuned precision and minimizing unwanted side effects. The chapter highlights recent advances in gene editing, synthetic gene circuits, and molecular engineering, showcasing how these technologies are optimizing CAR T-cell function. In summary, this book chapter sheds light on the remarkable progress made in the development of CAR T-cell therapies using synthetic biology, providing hope for cancer patients and hinting at a future where highly personalized and effective cancer treatments are the norm.

Chimeric antigen receptor T-cell therapy in hematologic malignancies: Successes, challenges, and opportunities

The success of chimeric antigen receptor T-cell (CAR-T) therapy in hematologic malignancies has realized a longstanding effort toward harnessing the immune system to fight cancer in a truly personalized fashion. Second generation chimeric antigen receptors (CAR) incorporating co-stimulatory molecules like 4-1BB or CD28 were able to overcome some of the hindrances with initial CAR constructs resulting in efficacious products. Many second-generation CAR-T products have been approved in the treatment of relapsed/refractory hematologic malignancies including multiple myeloma (MM), non-Hodgkin lymphoma (NHL), and acute lymphoblastic leukemia. However, challenges remain in optimizing the manufacturing, timely access, limiting the toxicity from CAR-T infusions and improving sustainability of responses derived with CAR-T therapy. Here, we summarize the clinical trial data leading to approval CAR-T therapies in MM and NHL, discuss the limitations with current CAR-T therapy strategies and review emerging strategies for overcoming these limitations.

NGAL Mediates Anaplastic Thyroid Carcinoma Cells Survival Through FAS/CD95 Inhibition

Neutrophil gelatinase-associated lipocalin (NGAL), a siderophore-mediated iron binding protein, is highly expressed in human anaplastic thyroid carcinomas (ATCs) where it plays pleiotropic protumorigenic roles including that of a prosurvival protein. Here we show that NGAL inhibits FAS/CD95 death receptor to control ATC cell survival. FAS/CD95 expression in human specimens from patients with ATC and in ATC-derived cell lines negatively correlate with NGAL expression. Silencing of NGAL in ATC cells leads to FAS/CD95 upregulation, whereas NGAL overexpression determines the opposite effect. As a result, an agonist anti-FAS/CD95 antibody induces cell death in NGAL-silenced cells while it is ineffective on NGAL-overexpressing cells. Interestingly, the inhibitory activity of NGAL on FAS/CD95 is due to its iron carrier property given that perturbing iron homeostasis of NGAL-proficient and -deficient ATC cells directly influences FAS/CD95 expression. Accordingly, conditioned media containing a mutant form of NGAL unable to bind siderophores cannot rescue cells from FAS/CD95-dependent death, whereas NGAL wild type-containing conditioned media abolish the effects of the agonist antibody. We also find that downregulation of FAS/CD95 expression is mediated by iron-dependent NGAL suppression of p53 transcriptional activity. Our results indicate that NGAL contributes to ATC cell survival by iron-mediated inhibition of p53-dependent FAS/CD95 expression and suggest that restoring FAS/CD95 by NGAL suppression could be a helpful strategy to kill ATC cells.

Regulation of DNA damage-induced HLA class I presentation

Immune checkpoint inhibitors (ICI) are cancer therapies that restore anti-tumor immunity; however, only a small percentage of patients have been completely cured by ICI alone. Multiple approaches in combination with other modalities have been used to improve the efficacy of ICI therapy. Among conventional cancer treatments, radiotherapy or DNA damage-based chemotherapy is a promising candidate as a partner of ICI because DNA damage signaling potentially stimulates immune activities turning the tumor's immune environment into hot tumors. Programmed death-ligand 1 (PD-L1) and human leukocyte antigen class I (HLA-I), which are immune ligands, regulate the balance of anti-tumor immunity in the tumor microenvironment. PD-L1 functions as a brake to suppress cytotoxic T cell activity, whereas HLA-I is an immune accelerator that promotes the downstream of the T cell signaling. Accumulating evidence has demonstrated that DNA damage enhances the presentation of HLA-I on the surface of damaged cells. However, it is unclear how signal transduction in DNA-damaged cells upregulates the presentation of HLA-I with antigens. Our recent study uncovered the mechanism underlying DNA damage-induced HLA-I presentation, which requires polypeptide synthesis through a pioneer round of translation. In this review, we summarize the latest overview of how DNA damage stimulates antigen production presented by HLA-I.

Loss of Dact2 alleviates cisplatin-induced nephrotoxicity through regulation of the Igfl-MAPK pathway axis

Wnt signaling is a principal pathway regulating the essential activities of cell proliferation. Here, we investigated the effect of Wnt/β-catenin signaling on in vivo drug-induced renal injury through the deletion of Dact2, a Wnt antagonist, and deciphered the underlying mechanism. Wild-type (WT) and Dact2 knockout (KO) mice were administered a single intraperitoneal injection of cisplatin to induce renal injury. The injury was alleviated in Dact2 KO mice, which showed lower levels of blood urea nitrogen and creatinine. RNA sequencing revealed 194 differentially expressed genes (DEGs) between WT and Dact2 KO mouse kidney before cisplatin treatment. Among them, higher levels of Igf1, one of the Wnt target genes responsible for "Positive regulation of cell proliferation" in KO mice, were confirmed along with the induction of Ki67 expression. In RNA-seq analysis comparing WT and Dact2 KO mice after cisplatin treatment, genes related to "Apoptosis" and "Activation of mitogen-activated protein kinase (MAPK) activity" were among the downregulated DEGs in KO mice. These results were corroborated in western blotting of proteins related to apoptosis and proapoptotic MAPK pathway; the expression of which was found to be lower in cisplatin-treated KO mice. Importantly, β-catenin was found to directly bind to and regulate the transcription of Igf1, leading to the alleviation of cisplatin-induced cytotoxicity by the Wnt agonist, CHIR-99021. In addition, Igf1 knockdown accelerated cisplatin-induced cytotoxicity, accompanied by the MAPK upregulation. Our findings suggest that Dact2 knockout could protect cisplatin-induced nephrotoxicity by inhibiting apoptosis, possibly through the regulation of the Igf1-MAPK axis associated with Wnt/β-catenin signaling.

The Important Role of Protein Kinases in the p53 Sestrin Signaling Pathway

p53, a crucial tumor suppressor and transcription factor, plays a central role in the maintenance of genomic stability and the orchestration of cellular responses such as apoptosis, cell cycle arrest, and DNA repair in the face of various stresses. Sestrins, a group of evolutionarily conserved proteins, serve as pivotal mediators connecting p53 to kinase-regulated anti-stress responses, with Sestrin 2 being the most extensively studied member of this protein family. These responses involve the downregulation of cell proliferation, adaptation to shifts in nutrient availability, enhancement of antioxidant defenses, promotion of autophagy/mitophagy, and the clearing of misfolded proteins. Inhibition of the mTORC1 complex by Sestrins reduces cellular proliferation, while Sestrin-dependent activation of AMP-activated kinase (AMPK) and mTORC2 supports metabolic adaptation. Furthermore, Sestrin-induced AMPK and Unc-51-like protein kinase 1 (ULK1) activation regulates autophagy/mitophagy, facilitating the removal of damaged organelles. Moreover, AMPK and ULK1 are involved in adaptation to changing metabolic conditions. ULK1 stabilizes nuclear factor erythroid 2-related factor 2 (Nrf2), thereby activating antioxidative defenses. An understanding of the intricate network involving p53, Sestrins, and kinases holds significant potential for targeted therapeutic interventions, particularly in pathologies like cancer, where the regulatory pathways governed by p53 are often disrupted.

Low glucose metabolite 3-phosphoglycerate switches PHGDH from serine synthesis to p53 activation to control cell fate

Glycolytic intermediary metabolites such as fructose-1,6-bisphosphate can serve as signals, controlling metabolic states beyond energy metabolism. However, whether glycolytic metabolites also play a role in controlling cell fate remains unexplored. Here, we find that low levels of glycolytic metabolite 3-phosphoglycerate (3-PGA) can switch phosphoglycerate dehydrogenase (PHGDH) from cataplerosis serine synthesis to pro-apoptotic activation of p53. PHGDH is a p53-binding protein, and when unoccupied by 3-PGA interacts with the scaffold protein AXIN in complex with the kinase HIPK2, both of which are also p53-binding proteins. This leads to the formation of a multivalent p53-binding complex that allows HIPK2 to specifically phosphorylate p53-Ser46 and thereby promote apoptosis. Furthermore, we show that PHGDH mutants (R135W and V261M) that are constitutively bound to 3-PGA abolish p53 activation even under low glucose conditions, while the mutants (T57A and T78A) unable to bind 3-PGA cause constitutive p53 activation and apoptosis in hepatocellular carcinoma (HCC) cells, even in the presence of high glucose. In vivo, PHGDH-T57A induces apoptosis and inhibits the growth of diethylnitrosamine-induced mouse HCC, whereas PHGDH-R135W prevents apoptosis and promotes HCC growth, and knockout of Trp53 abolishes these effects above. Importantly, caloric restriction that lowers whole-body glucose levels can impede HCC growth dependent on PHGDH. Together, these results unveil a mechanism by which glucose availability autonomously controls p53 activity, providing a new paradigm of cell fate control by metabolic substrate availability.

Chemosensitivity to doxorubicin in primary cells derived from tumor of FVB/N-Trp53tm1Hw1 with TALEN-mediated Trp53 mutant gene

BACKGROUND

To evaluate the chemosensitivity to doxorubicin (DOX) in two primary cells derived from a tumor of FVB/N-Trp53tm1Hw1 knockout (KO) mice with TALEN-mediated Trp53 mutant gene, we evaluated the cell survivability, cell cycle distribution, apoptotic cell numbers and apoptotic protein expression in solid tumor cells and ascetic tumor cells treated with DOX.

RESULTS

The primary tumor cells showed a significant (P < 0.05) defect for UV-induced upregulation of the Trp53 protein, and consisted of different ratios of leukocytes, fibroblasts, epithelial cells and mesenchymal cells. The IC50 level to DOX was lower in both primary cells (IC50 = 0.12 μM and 0.20 μM) as compared to the CT26 cells (IC50 = 0.32 μM), although the solid tumor was more sensitive. Also, the number of cells arrested at the G0/G1 stage was significantly decreased (24.7-23.1% in primary tumor cells treated with DOX, P < 0.05) while arrest at the G2 stage was enhanced to 296.8-254.3% in DOX-treated primary tumor cells compared with DOX-treated CT26 cells. Furthermore, apoptotic cells of early and late stage were greatly increased in the two primary cell-lines treated with DOX when compared to same conditions for CT26 cells. However, the Bax/Bcl-2 expression level was maintained constant in the primary tumor and CT26 cells.

CONCLUSIONS

To the best of our knowledge, these results are the first to successfully detect an alteration in chemosensitivity to DOX in solid tumor cells and ascetic tumor cells derived from tumor of FVB/N-Trp53tm1Hw1 mice TALEN-mediated Trp53 mutant gene.

Comparative studies on in vitro antitumor activities and apoptosis-inducing effects of enantiomeric ruthenium(II) complexes

On the basis of our previous comparative studies on the DNA binding of a pair of ruthenium(II) complex enantiomers, Δ-[Ru(bpy)2PBIP]2+ and Λ-[Ru(bpy)2PBIP]2+ {bpy = 2,2'-bipyridine, PBIP = 2-(4-bromophenyl)imidazo[4,5-f]1,10-phenanthroline}, in this study, their antitumor activities and mechanisms were further investigated comparatively. The cytotoxicity assay demonstrated that both the enantiomers exerted selective antiproliferative effects on cancer cell lines A2780 and PC3. Fluorescence localization experiments suggested that both the enantiomers effectively permeated the nucleus of HeLa cells and co-localized with DNA, resulting in their DNA damage and apoptosis. Flow cytometry experiments showed that the apoptosis was enhanced by increasing the concentration of each enantiomer. Western blotting analyses indicated that both extrinsic and intrinsic apoptosis pathways were activated by the two enantiomers. miRNA microarray analyses displayed that both the enantiomers up- and downregulated multiple miRNAs, some of which were predicted to be associated with carcinogenesis. The above experimental results also showed that the Δ-enantiomer exerted a more potent antitumor activity, a higher efficiency of entering cancer cells and a stronger apoptosis-inducing effect compared with the Λ-enantiomer. Combined with the previously published research results, experimental results from this study implied that the antitumor activity of a metal complex might have originated from the conformation change of DNA in tumor cells caused by the intercalation of the complex, that the antitumor mechanism of a metal complex could be related to its DNA-binding mode, and that the antitumor efficiency of a metal complex could result from its DNA-binding strength.

A lncRNA from the FTO locus acts as a suppressor of the m6A writer complex and p53 tumor suppression signaling

N6-methyladenosine (m6A) of mRNAs modulated by the METTL3-METTL14-WTAP-RBM15 methyltransferase complex and m6A demethylases such as FTO play important roles in regulating mRNA stability, splicing, and translation. Here, we demonstrate that FTO-IT1 long noncoding RNA (lncRNA) was upregulated and positively correlated with poor survival of patients with wild-type p53-expressing prostate cancer (PCa). m6A RIP-seq analysis revealed that FTO-IT1 knockout increased mRNA m6A methylation of a subset of p53 transcriptional target genes (e.g., FAS, TP53INP1, and SESN2) and induced PCa cell cycle arrest and apoptosis. We further showed that FTO-IT1 directly binds RBM15 and inhibits RBM15 binding, m6A methylation, and stability of p53 target mRNAs. Therapeutic depletion of FTO-IT1 restored mRNA m6A level and expression of p53 target genes and inhibited PCa growth in mice. Our study identifies FTO-IT1 lncRNA as a bona fide suppressor of the m6A methyltransferase complex and p53 tumor suppression signaling and nominates FTO-IT1 as a potential therapeutic target of cancer.

The role of p53 in anti-tumor immunity and response to immunotherapy

p53 is a transcription factor that regulates the expression of genes involved in tumor suppression. p53 mutations mediate tumorigenesis and occur in approximately 50% of human cancers. p53 regulates hundreds of target genes that induce various cell fates including apoptosis, cell cycle arrest, and DNA damage repair. p53 also plays an important role in anti-tumor immunity by regulating TRAIL, DR5, TLRs, Fas, PKR, ULBP1/2, and CCL2; T-cell inhibitory ligand PD-L1; pro-inflammatory cytokines; immune cell activation state; and antigen presentation. Genetic alteration of p53 can contribute to immune evasion by influencing immune cell recruitment to the tumor, cytokine secretion in the TME, and inflammatory signaling pathways. In some contexts, p53 mutations increase neoantigen load which improves response to immune checkpoint inhibition. Therapeutic restoration of mutated p53 can restore anti-cancer immune cell infiltration and ameliorate pro-tumor signaling to induce tumor regression. Indeed, there is clinical evidence to suggest that restoring p53 can induce an anti-cancer immune response in immunologically cold tumors. Clinical trials investigating the combination of p53-restoring compounds or p53-based vaccines with immunotherapy have demonstrated anti-tumor immune activation and tumor regression with heterogeneity across cancer type. In this Review, we discuss the impact of wild-type and mutant p53 on the anti-tumor immune response, outline clinical progress as far as activating p53 to induce an immune response across a variety of cancer types, and highlight open questions limiting effective clinical translation.

FIT links c-Myc and P53 acetylation by recruiting RBBP7 during colorectal carcinogenesis

Colorectal cancer (CRC) poses one of the most serious threats to human health worldwide, and abnormally expressed c-Myc and p53 are deemed the pivotal driving forces of CRC progression. In this study, we discovered that the lncRNA FIT, which was downregulated in CRC clinical samples, was transcriptionally suppressed by c-Myc in vitro and promoted CRC cell apoptosis by inducing FAS expression. FAS is a p53 target gene, and we found that FIT formed a trimer with RBBP7 and p53 that facilitated p53 acetylation and p53-mediated FAS gene transcription. Moreover, FIT was capable of retarding CRC growth in a mouse xenograft model, and FIT expression was positively correlated with FAS expression in clinical samples. Thus, our study elucidates the role of the lncRNA FIT in human colorectal cancer growth and provides a potential target for anti-CRC drugs.

The Role of FAS Receptor Methylation in Osteosarcoma Metastasis

Osteosarcoma is the most frequent primary malignant bone tumor with an annual incidence of about 400 cases in the United States. Osteosarcoma primarily metastasizes to the lungs, where FAS ligand (FASL) is constitutively expressed. The interaction of FASL and its cell surface receptor, FAS, triggers apoptosis in normal cells; however, this function is altered in cancer cells. DNA methylation has previously been explored as a mechanism for altering FAS expression, but no variability was identified in the CpG island (CGI) overlapping the promoter. Analysis of an expanded region, including CGI shores and shelves, revealed high variability in the methylation of certain CpG sites that correlated significantly with FAS mRNA expression in a negative manner. Bisulfite sequencing revealed additional CpG sites, which were highly methylated in the metastatic LM7 cell line but unmethylated in its parental non-metastatic SaOS-2 cell line. Treatment with the demethylating agent, 5-azacytidine, resulted in a loss of methylation in CpG sites located within the FAS promoter and restored FAS protein expression in LM7 cells, resulting in reduced migration. Orthotopic implantation of 5-azacytidine treated LM7 cells into severe combined immunodeficient mice led to decreased lung metastases. These results suggest that DNA methylation of CGI shore sites may regulate FAS expression and constitute a potential target for osteosarcoma therapy, utilizing demethylating agents currently approved for the treatment of other cancers.

Simultaneous Inhibition of Mcl-1 and Bcl-2 Induces Synergistic Cell Death in Hepatocellular Carcinoma

Despite the recent approval of new therapies, the prognosis for patients with hepatocellular carcinoma (HCC) remains poor. There is a clinical need for new highly effective therapeutic options. Here, we present a combined application of BH3-mimetics as a potential new treatment option for HCC. BH3-mimetics inhibit anti-apoptotic proteins of the BCL-2 family and, thus, trigger the intrinsic apoptosis pathway. Anti-apoptotic BCL-2 proteins such as Bcl-2 and Mcl-1 are frequently overexpressed in HCC. Therefore, we analyzed the efficacy of the two BH3-mimetics ABT-199 (Bcl-2 inhibitor) and MIK665 (Mcl-1 inhibitor) in HCC cell lines with differential expression levels of endogenous Bcl-2 and Mcl-1. While administration of one BH3-mimetic alone did not substantially trigger cell death, the combination of two inhibitors enhanced induction of the intrinsic apoptosis pathway. Both drugs acted synergistically, highlighting the effectivity of this specific BH3-mimetic combination, particularly in HCC cell lines. These results indicate the potential of combining inhibitors of the BCL-2 family as new therapeutic options in HCC.

Proteomic analysis reveals microvesicles containing NAMPT as mediators of radioresistance in glioma

Tumor-initiating cells contained within the aggressive brain tumor glioma (glioma stem cells, GSCs) promote radioresistance and disease recurrence. However, mechanisms of resistance are not well understood. Herein, we show that the proteome-level regulation occurring upon radiation treatment of several patient-derived GSC lines predicts their resistance status, whereas glioma transcriptional subtypes do not. We identify a mechanism of radioresistance mediated by the transfer of the metabolic enzyme NAMPT to radiosensitive cells through microvesicles (NAMPT-high MVs) shed by resistant GSCs. NAMPT-high MVs rescue the proliferation of radiosensitive GSCs and fibroblasts upon irradiation, and upon treatment with a radiomimetic drug or low serum, and increase intracellular NAD(H) levels. Finally, we show that the presence of NAMPT within the MVs and its enzymatic activity in recipient cells are necessary to mediate these effects. Collectively, we demonstrate that the proteome of GSCs provides unique information as it predicts the ability of glioma to resist radiation treatment. Furthermore, we establish NAMPT transfer via MVs as a mechanism for rescuing the proliferation of radiosensitive cells upon irradiation.

CD95/Fas ligand mRNA is toxic to cells through more than one mechanism

CD95/Fas ligand (CD95L) induces apoptosis through protein binding to the CD95 receptor. However, CD95L mRNA also induces toxicity in the absence of CD95 through induction of DISE (Death Induced by Survival Gene Elimination), a form of cell death mediated by RNA interference (RNAi). We now report that CD95L mRNA processing generates a short (s)RNA nearly identical to shL3, a commercial CD95L-targeting shRNA that led to the discovery of DISE. Neither of the miRNA biogenesis proteins Drosha nor Dicer are required for this processing. Interestingly, CD95L toxicity depends on the core component of the RISC, Ago2, in some cell lines, but not in others. In the HCT116 colon cancer cell line, Ago 1-4 appear to function redundantly in RNAi. In fact, Ago 1/2/3 knockout cells retain sensitivity to CD95L mRNA toxicity. Toxicity was only blocked by mutation of all in-frame start codons in the CD95L ORF. Dying cells exhibited an enrichment of RISC bound (R)-sRNAs with toxic 6mer seed sequences, while expression of the non-toxic CD95L mutant enriched for loading of R-sRNAs with nontoxic 6mer seeds. However, CD95L is not the only source of these R-sRNAs. We find that CD95L mRNA may induce DISE directly and indirectly, and that alternate mechanisms may underlie CD95L mRNA processing and toxicity.

Arsenite-induced cytotoxicity is regulated by poly-ADP ribose polymerase 1 activation and parthanatos in p53-deficient H1299 cells: The roles of autophagy and p53

Arsenic is a double-edged sword metalloid since it is both an environmental carcinogen and a chemopreventive agent. Arsenic cytotoxicity can be dependent or independent of the tumor suppressor p53. However, the effects and the underlying molecular mechanisms of arsenic cytotoxicity in p53-deficient cells are still unclear. Here, we report a distinctive cell death mode via PARP-1 activation by arsenic in p53-deficient H1299 cells. H1299 (p53^-/-) cells showed higher sensitivity to sodium arsenite (NaAR) than H460 (p53^+/+) cells. H460 cells induced canonical apoptosis through caspase-dependent poly-ADP ribose polymerase 1 (PARP-1) cleavage and induced the expression of phospho-p53 and p21. However, H1299 cells induced poly-ADP-ribose (PAR) polymer accumulation and caspase-independent parthanatos, which was inhibited by 3-aminobenzamide (AB) and nicotinamide (NAM). Fractionation studies revealed the mitochondrial translocation of PAR polymers and nuclear translocation of the apoptosis-inducing factor (AIF). Although the exposure of NaAR to p53-overexpressing H1299 cells increased the PAR polymer levels, it inhibited parthanatos by inducing p21 and phospho-p53 expression. LC3-II and p62 accumulated in a NaAR dose- and exposure time-dependent manner, and this accumulation was further enhanced by autophagy inhibition, indicating that arsenic inhibits autophagic flux. p53 overexpression led to a decrease in the p62 levels, an increase in the LC3-II levels, and reduced parthanatos, indicating that arsenic induces p53-dependent functional autophagy. These results show that the NaAR-induced cytotoxicity in p53-deficient H1299 cells is regulated by PARP-1 activation-mediated parthanatos, which is promoted by autophagy inhibition. This suggests that PARP-1 activation could be used as an effective therapeutic approach for arsenic toxicity in p53-deficient cells.

5-Fluorouracil Suppresses Colon Tumor through Activating the p53-Fas Pathway to Sensitize Myeloid-Derived Suppressor Cells to FasL+ Cytotoxic T Lymphocyte Cytotoxicity

Myelosuppression is a major adverse effect of 5-fluorouracil (5-FU) chemotherapy. However, recent findings indicate that 5-FU selectively suppresses myeloid-derived suppressor cells (MDSCs), to enhance antitumor immunity in tumor-bearing mice. 5-FU-mediated myelosuppression may thus have a beneficial effect for cancer patients. The molecular mechanism underlying 5-FU's suppression of MDSCs is currently unknown. We aimed at testing the hypothesis that 5-FU suppresses MDSCs through enhancing MDSC sensitivity to Fas-mediated apoptosis. We observed that, although FasL is highly expressed in T cells, Fas is weakly expressed in myeloid cells in human colon carcinoma, indicating that downregulation of Fas is a mechanism underlying myeloid cell survival and accumulation in human colon cancer. 5-FU treatment upregulated expression of both p53 and Fas, and knocking down p53 diminished 5-FU-induced Fas expression in MDSC-like cells, in vitro. 5-FU treatment also increased MDSC-like cell sensitivity to FasL-induced apoptosis in vitro. Furthermore, we determined that 5-FU therapy increased expression of Fas on MDSCs, suppressed MDSC accumulation, and increased CTL tumor infiltration in colon tumor-bearing mice. In human colorectal cancer patients, 5-FU chemotherapy decreased MDSC accumulation and increased CTL level. Our findings determine that 5-FU chemotherapy activates the p53-Fas pathway, to suppress MDSC accumulation, to increase CTL tumor infiltration.

Targeting p53 pathways: mechanisms, structures, and advances in therapy

The TP53 tumor suppressor is the most frequently altered gene in human cancers, and has been a major focus of oncology research. The p53 protein is a transcription factor that can activate the expression of multiple target genes and plays critical roles in regulating cell cycle, apoptosis, and genomic stability, and is widely regarded as the "guardian of the genome". Accumulating evidence has shown that p53 also regulates cell metabolism, ferroptosis, tumor microenvironment, autophagy and so on, all of which contribute to tumor suppression. Mutations in TP53 not only impair its tumor suppressor function, but also confer oncogenic properties to p53 mutants. Since p53 is mutated and inactivated in most malignant tumors, it has been a very attractive target for developing new anti-cancer drugs. However, until recently, p53 was considered an "undruggable" target and little progress has been made with p53-targeted therapies. Here, we provide a systematic review of the diverse molecular mechanisms of the p53 signaling pathway and how TP53 mutations impact tumor progression. We also discuss key structural features of the p53 protein and its inactivation by oncogenic mutations. In addition, we review the efforts that have been made in p53-targeted therapies, and discuss the challenges that have been encountered in clinical development.

CD95/Fas ligand induced toxicity

The role of CD95/Fas ligand (CD95L/FasL) in the induction of CD95-mediated extrinsic apoptosis is well characterized. Trimerized, membrane-bound CD95L ligates the CD95 receptor activating downstream signaling resulting in the execution of cells by caspase proteins. However, the expression of CD95L has been reported to induce cell death in contexts in which this pathway is unlikely to be activated, such as in cell autonomous activation induced cell death (AICD) and in CD95-resistant cancer cell lines. Recent data suggests that the CD95L mRNA exerts toxicity through death induced by survival gene elimination (DISE). DISE results from the targeting of networks of survival genes by toxic short RNA (sRNA)s in the RNA-induced silencing complex (RISC). CD95L mRNA contributes to this death directly, through the processing of its mRNA into toxic sRNAs that are loaded into the RISC, and indirectly, by promoting the loading of other toxic sRNAs. Interestingly, CD95L is not the only mRNA that is processed and loaded into the RISC. Protein-coding mRNAs involved in protein translation are also selectively loaded. We propose a model in which networks of mRNA-derived sRNAs modulate DISE, with networks of genes providing non-toxic RISC substrate sRNAs that protect against DISE, and opposing networks of stress-activated genes that produce toxic RISC substrate sRNAs that promote DISE.

Adaptive resistance is not responsible for long-term drug resistance in a cellular model of triple negative breast cancer

Resistance to cancer therapeutics represents a leading cause of mortality and is particularly important in cancers, such as triple negative breast cancer, for which no targeted therapy is available, as these are only treated with traditional chemotherapeutics. Cancer, as well as bacterial, drug resistance can be intrinsic, acquired or adaptive. Adaptive cancer drug resistance is gaining attention as a mechanism for the generation of long-term drug resistance as is the case with bacterial antibiotic resistance. We have used a cellular model of triple negative breast cancer (CAL51) and its drug resistance derivative (CALDOX) to gain insight into genome-wide expression changes associated with long-term doxorubicin (a widely used anthracycline for cancer treatment) resistance and doxorubicin-induced stress. Previous work indicates that both naïve and resistance cells have a functional p53-p21 axis controlling cell cycle at G1, although this is not a driver for drug resistance, but down-regulation of TOP2A (topoisomerase IIα). As expected, CALDOX cells have a signature characterized, in addition to down-regulation of TOP2A, by genes and pathways associated with drug resistance, metastasis and stemness. Both CAL51 and CALDOX stress signatures share 12 common genes (TRIM22, FAS, SPATA18, SULF2, CDKN1A, GDF15, MYO6, CXCL5, CROT, EPPK1, ZMAT3 and CD44), with roles in the above-mentioned pathways, indicating that these cells have similar functional responses to doxorubicin relaying on the p53 control of apoptosis. Eight genes are shared by both drug stress signatures (in CAL51 and CALDOX cells) and CALDOX resistant cells (FAS, SULF2, CDKN1A, CXCL5, CD44, SPATA18, TRIM22 and CROT), many of them targets of p53. This corroborates experimental data indicating that CALDOX cells, even in the absence of drug, have activated, at least partially, the p53-p21 axis and DNA damage response. Although this eight-gene signature might be an indicator of adaptive resistance, as this transient phenomenon due to short-term stress may not revert to its original state upon withdrawal of the stressor, previous experimental data indicates that the p53-p21 axis is not responsible for doxorubicin resistance. Importantly, TOP2A is not responsive to doxorubicin treatment and thus absent in both drug stress signatures. This indicates that during the generation of doxorubicin resistance, cells acquire genetic changes likely to be random, leading to down regulation of TOP2A, but selected during the generation of cells due to the presence of drug in the culture medium. This poses a considerable constraint for the development of strategies aimed at avoiding the emergence of drug resistance in the clinic.

Pathogenesis and Current Treatment Strategies of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most frequent liver cancer with high lethality and low five-year survival rates leading to a substantial worldwide burden for healthcare systems. HCC initiation and progression are favored by different etiological risk factors including hepatitis B virus (HBV) and hepatitis C virus (HCV) infection, non-/and alcoholic fatty liver disease (N/AFLD), and tobacco smoking. In molecular pathogenesis, endogenous alteration in genetics (TP53, TERT, CTNNB1, etc.), epigenetics (DNA-methylation, miRNA, lncRNA, etc.), and dysregulation of key signaling pathways (Wnt/β-catenin, JAK/STAT, etc.) strongly contribute to the development of HCC. The multitude and complexity of different pathomechanisms also reflect the difficulties in tailored medical therapy of HCC. Treatment options for HCC are strictly dependent on tumor staging and liver function, which are structured by the updated Barcelona Clinic Liver Cancer classification system. Surgical resection, local ablative techniques, and liver transplantation are valid and curative therapeutic options for early tumor stages. For multifocal and metastatic diseases, systemic therapy is recommended. While Sorafenib had been the standalone HCC first-line therapy for decades, recent developments had led to the approval of new treatment options as first-line as well as second-line treatment. Anti-PD-L1 directed combination therapies either with anti-VEGF directed agents or with anti-CTLA-4 active substances have been implemented as the new treatment standard in the first-line setting. However, data from clinical trials indicate different responses on specific therapeutic regimens depending on the underlying pathogenesis of hepatocellular cancer. Therefore, histopathological examinations have been re-emphasized by current international clinical guidelines in addition to the standardized radiological diagnosis using contrast-enhanced cross-sectional imaging. In this review, we emphasize the current knowledge on molecular pathogenesis of hepatocellular carcinoma. On this occasion, the treatment sequences for early and advanced tumor stages according to the recently updated Barcelona Clinic Liver Cancer classification system and the current algorithm of systemic therapy (first-, second-, and third-line treatment) are summarized. Furthermore, we discuss novel precautional and pre-therapeutic approaches including therapeutic vaccination, adoptive cell transfer, locoregional therapy enhancement, and non-coding RNA-based therapy as promising treatment options. These novel treatments may prolong overall survival rates in regard with quality of life and liver function as mainstay of HCC therapy.

Insight into the interplay between mitochondria-regulated cell death and energetic metabolism in osteosarcoma

Osteosarcoma (OS) is a pediatric malignant bone tumor that predominantly affects adolescent and young adults. It has high risk for relapse and over the last four decades no improvement of prognosis was achieved. It is therefore crucial to identify new drug candidates for OS treatment to combat drug resistance, limit relapse, and stop metastatic spread. Two acquired hallmarks of cancer cells, mitochondria-related regulated cell death (RCD) and metabolism are intimately connected. Both have been shown to be dysregulated in OS, making them attractive targets for novel treatment. Promising OS treatment strategies focus on promoting RCD by targeting key molecular actors in metabolic reprogramming. The exact interplay in OS, however, has not been systematically analyzed. We therefore review these aspects by synthesizing current knowledge in apoptosis, ferroptosis, necroptosis, pyroptosis, and autophagy in OS. Additionally, we outline an overview of mitochondrial function and metabolic profiles in different preclinical OS models. Finally, we discuss the mechanism of action of two novel molecule combinations currently investigated in active clinical trials: metformin and the combination of ADI-PEG20, Docetaxel and Gemcitabine.

Exploring the effects of Chinese herbal ingredients on the signaling pathway of alopecia and the screening of effective Chinese herbal compounds

ETHNOPHARMACOLOGICAL RELEVANCE

alopecia is a hair disorder that can add a significant medical and psychological burden to patients. Currently, the FDA-approved drugs for the treatment of androgenetic alopecia (AGA) are minoxidil and finasteride and immunosuppressives are therapeutic options for alopecia areata (AA), but the objective adverse effects and high cost of these treatments reduce patient compliance and thus the effectiveness of the drugs. Traditional Chinese medicine (TCM) has good efficacy, a high safety profile and low treatment costs, but its mechanism of action is still not fully understood. The use of signaling pathways to modulate hair loss is a major direction in the study of the pathogenesis and pharmacology of alopecia.

AIM OF THE STUDY

This review aims to collect the results of experimental studies related to alopecia, to screen previously documented combinations of herbs claimed to be effective based on the herbs and their constituent compounds used in the identified studies, and to uncover other useful information that we hope will better guide the clinical application and scientific research of drug combinations or individual herbs for the treatment of alopecia.

MATERIALS AND METHODS

We have reviewed experimental studies to determine the methods used and the mechanisms of action of the herbs and constituent compounds. The following keywords were searched in databases, including PubMed, EMBASE, CNKI and CSTJ." Medicinal plants" "Chinese herbal medicine", "hair loss", " alopecia", "androgenetic alopecia" and " alopecia areata ". We also collected combinations of drugs from books approved by various schools for screening.

RESULTS

Using known combinations of compounds within herbal medicine to match the documented combinations, 34 topical combinations and 74 oral combinations were identified, and among the 108 herbal combinations screened Angelica, Rehmannia glutinosaLigusticum chuanxiong hort, Radix Rehmanniae, etc. The number of occurrences was very high, and the association with vascular drugs was also found to be very close.

CONCLUSIONS

This review further elucidates the therapeutic mechanisms of the compounds within the herbal components associated with alopecia and screens for other combinations that may be dominated by this component for the treatment of alopecia, uncovering compounds from other drugs that may be key factors in the treatment of alopecia. This improvement will provide a better quality of evidence for the effectiveness of herbs and compounds used to treat alopecia.

3-Chloro-3-methyl-2,6-diarylpiperidin-4-ones as Anti-Cancer Agents: Synthesis, Biological Evaluation, Molecular Docking, and In Silico ADMET Prediction

Piperidine pharmacophore-containing compounds have demonstrated therapeutic efficacy against a range of diseases and are now being investigated in cancer. A series of 3-chloro-3-methyl-2,6-diarylpiperidin-4-ones, compounds (I–V) were designed and synthesized for their evaluation as a potential anti-cancer agent. Compounds II and IV reduced the growth of numerous hematological cancer cell lines while simultaneously increasing the mRNA expression of apoptosis-promoting genes, p53 and Bax. Molecular docking analyses confirmed that compounds can bind to 6FS1, 6FSO (myeloma), 6TJU (leukemia), 5N21, and 1OLL (NKTL). Computational ADMET research confirmed the essential physicochemical, pharmacokinetic, and drug-like characteristics of compounds (I–V). The results revealed that these compounds interact efficiently with active site residues and that compounds (II) and (V) can be further evaluated as potential therapeutic candidates.

3-Chloro-3-methyl-2,6-diarylpiperidin-4-ones as Anti-Cancer Agents: Synthesis, Biological Evaluation, Molecular Docking, and In Silico ADMET Prediction

Piperidine pharmacophore-containing compounds have demonstrated therapeutic efficacy against a range of diseases and are now being investigated in cancer. A series of 3-chloro-3-methyl-2,6-diarylpiperidin-4-ones, compounds (I–V) were designed and synthesized for their evaluation as a potential anti-cancer agent. Compounds II and IV reduced the growth of numerous hematological cancer cell lines while simultaneously increasing the mRNA expression of apoptosis-promoting genes, p53 and Bax. Molecular docking analyses confirmed that compounds can bind to 6FS1, 6FSO (myeloma), 6TJU (leukemia), 5N21, and 1OLL (NKTL). Computational ADMET research confirmed the essential physicochemical, pharmacokinetic, and drug-like characteristics of compounds (I–V). The results revealed that these compounds interact efficiently with active site residues and that compounds (II) and (V) can be further evaluated as potential therapeutic candidates.

The cross-talk of autophagy and apoptosis in breast carcinoma: implications for novel therapies?

Breast cancer is still the most common cancer in women worldwide. Resistance to drugs and recurrence of the disease are two leading causes of failure in treatment. For a more efficient treatment of patients, the development of novel therapeutic regimes is needed. Recent studies indicate that modulation of autophagy in concert with apoptosis induction may provide a promising novel strategy in breast cancer treatment. Apoptosis and autophagy are two tightly regulated distinct cellular processes. To maintain tissue homeostasis abnormal cells are disposed largely by means of apoptosis. Autophagy, however, contributes to tissue homeostasis and cell fitness by scavenging of damaged organelles, lipids, proteins, and DNA. Defects in autophagy promote tumorigenesis, whereas upon tumor formation rapidly proliferating cancer cells may rely on autophagy to survive. Given that evasion of apoptosis is one of the characteristic hallmarks of cancer cells, inhibiting autophagy and promoting apoptosis can negatively influence cancer cell survival and increase cell death. Hence, combination of antiautophagic agents with the enhancement of apoptosis may restore apoptosis and provide a therapeutic advantage against breast cancer. In this review, we discuss the cross-talk of autophagy and apoptosis and the diverse facets of autophagy in breast cancer cells leading to novel models for more effective therapeutic strategies.

Lethal and Non-Lethal Functions of Caspases in the DNA Damage Response

Members of the caspase family are well known for their roles in the initiation and execution of cell death. Due to their function in the removal of damaged cells that could otherwise become malignant, caspases are important players in the DNA damage response (DDR), a network of pathways that prevent genomic instability. However, emerging evidence of caspases positively or negatively impacting the accumulation of DNA damage in the absence of cell death demonstrates that caspases play a role in the DDR that is independent of their role in apoptosis. This review highlights the apoptotic and non-apoptotic roles of caspases in the DDR and how they can impact genomic stability and cancer treatment.

TP53-inducible putative long noncoding RNAs encode functional polypeptides that suppress cell proliferation

Polypeptides encoded by long non-coding RNAs (lncRNAs) are a novel class of functional molecules. However, whether these hidden polypeptides participate in the TP53 pathway and play a significant biological role is still unclear. Here, we discover that TP53-regulated lncRNAs encode peptides, two of which are functional in various human cell lines. Using ribosome profiling and RNA-seq approaches in HepG2 cells, we systematically identified more than 300 novel TP53-regulated lncRNAs and further confirmed that fifteen of these TP53-regulated lncRNAs encode peptides. Furthermore, several peptides were validated by multiple mass spectrometry measures. Ten of the novel translational lncRNAs were directly inducible by TP53 in response to DNA damage. Notably, we showed that the TP53-inducible peptides TP53LC02 and TP53LC04, but not their lncRNAs, could suppress cell proliferation. TP53LC04 peptide also had a function associated with cell proliferation by regulating the cell cycle in response to DNA damage. This study demonstrates that TP53-inducible lncRNAs encode new functional peptides, leading to the enlargement of the components of TP53 tumor suppressor network and providing novel potential targets for cancer therapy.

Therapeutic approaches targeting CD95L/CD95 signaling in cancer and autoimmune diseases

Cell death plays a pivotal role in the maintenance of tissue homeostasis. Key players in the controlled induction of cell death are the Death Receptors (DR). CD95 is a prototypic DR activated by its cognate ligand CD95L triggering programmed cell death. As a consequence, alterations in the CD95/CD95L pathway have been involved in several disease conditions ranging from autoimmune diseases to inflammation and cancer. CD95L-induced cell death has multiple roles in the immune response since it constitutes one of the mechanisms by which cytotoxic lymphocytes kill their targets, but it is also involved in the process of turning off the immune response. Furthermore, beyond the canonical pro-death signals, CD95L, which can be membrane-bound or soluble, also induces non-apoptotic signaling that contributes to its tumor-promoting and pro-inflammatory roles. The intent of this review is to describe the role of CD95/CD95L in the pathophysiology of cancers, autoimmune diseases and chronic inflammation and to discuss recently patented and emerging therapeutic strategies that exploit/block the CD95/CD95L system in these diseases.

Doxorubicin sensitizes breast cancer cells to natural killer cells in connection with increased Fas receptors

Breast cancer (BC) is the most common cancer in women. Although standard treatments are successful in patients with BC diagnosed at an early stage, an alternative treatment is required for patients with advanced-stage disease who do not respond to these treatments. The concept of using chemotherapy to sensitize cancer cells to become susceptible to immunotherapy was recently introduced and may be used as an alternative treatment for BC. The chemotherapeutic drug doxorubicin has been reported to sensitize cancer cells; however, the efficacy to sensitize the solid spheroids, in addition to its underlying mechanism regarding how doxorubicin sensitizes BC, has not previously been explored. In the present study, the effectiveness of a combined treatment of doxorubicin and natural killer-92 (NK-92) cells against BC in either 2D or 3D spheroid models, and its association with Fas receptor (FasR) expression, was demonstrated. The BC (MCF7) cell line expressing a higher level of FasR was more sensitive to NK-92 cell killing than the MDA-MB-231 cell line, which expressed a lower level of FasR. A sublethal dose of doxorubicin caused a significant improvement in NK cytotoxicity. Concordantly, a significant reduction in cell viability was observed in the doxorubicin-treated MCF7 spheroids. Notably, flow cytometric analysis revealed significantly increased FasR expression in the MCF7 cells, suggesting the underlying sensitization mechanism of doxorubicin in BC was related to the FasR upregulation. The present findings supported the use of combined doxorubicin and NK immunotherapy in BC treatment.

Overcoming Intrinsic Resistance of Cancer Cells to CAR T-Cell Killing

In the past few years, chimeric antigen receptor (CAR) T-cell therapy has emerged as a promising treatment for cancers that failed standard treatments. Such therapies have already been approved in several blood cancers, such as B-cell leukemia and lymphoma. Despite this progress, a significant proportion of patients experience primary or secondary resistance to CAR T-cell therapy. Here, we review the mechanisms by which CAR T cells eliminate their target and how cancer cells may be insensitive to such killing (here referred to as intrinsic resistance). Recent studies suggest that the activation of apoptosis through death receptor signaling is responsible for a major part of CAR T-cell cytotoxicity in vivo Indeed, cancer cells harboring aberrant apoptotic machinery may be insensitive to CAR T-cell killing. This intrinsic resistance of cancer cells to CAR T-cell killing could be responsible for a significant portion of treatment failure. Finally, we discuss strategies that may be envisioned to overcome such resistance to enhance CAR T-cell efficacy.

Born to survive: how cancer cells resist CAR T cell therapy

Although chimeric antigen receptor T cells demonstrated remarkable efficacy in patients with chemo-resistant hematologic malignancies, a significant portion still resist or relapse. This immune evasion may be due to CAR T cells dysfunction, a hostile tumor microenvironment, or resistant cancer cells. Here, we review the intrinsic resistance mechanisms of cancer cells to CAR T cell therapy and potential strategies to circumvent them.

Cellular stress response to extremely low-frequency electromagnetic fields (ELF-EMF): An explanation for controversial effects of ELF-EMF on apoptosis

Impaired apoptosis is one of the hallmarks of cancer, and almost all of the non‐surgical approaches of eradicating tumour cells somehow promote induction of apoptosis. Indeed, numerous studies have stated that non‐ionizing non‐thermal extremely low‐frequency magnetic fields (ELF‐MF) can modulate the induction of apoptosis in exposed cells; however, much controversy exists in observations. When cells are exposed to ELF‐EMF alone, very low or no statistically significant changes in apoptosis are observed. Contrarily, exposure to ELF‐EMF in the presence of a co‐stressor, including a chemotherapeutic agent or ionizing radiation, can either potentiate or inhibit apoptotic effects of the co‐stressor. In our idea, the main point neglected in interpreting these discrepancies is “the cellular stress responses” of cells following ELF‐EMF exposure and its interplay with apoptosis. The main purpose of the current review was to outline the triangle of ELF‐EMF, the cellular stress response of cells and apoptosis and to interpret and unify discrepancies in results based on it. Therefore, initially, we will describe studies performed on identifying the effect of ELF‐EMF on induction/inhibition of apoptosis and enumerate proposed pathways through which ELF‐EMF exposure may affect apoptosis; then, we will explain cellular stress response and cues for its induction in response to ELF‐EMF exposure; and finally, we will explain why such controversies have been observed by different investigators.

Targeting the DNA damage response in immuno-oncology: developments and opportunities

Immunotherapy has revolutionized cancer treatment and substantially improved patient outcome with regard to multiple tumour types. However, most patients still do not benefit from such therapies, notably because of the absence of pre-existing T cell infiltration. DNA damage response (DDR) deficiency has recently emerged as an important determinant of tumour immunogenicity. A growing body of evidence now supports the concept that DDR-targeted therapies can increase the antitumour immune response by (1) promoting antigenicity through increased mutability and genomic instability, (2) enhancing adjuvanticity through the activation of cytosolic immunity and immunogenic cell death and (3) favouring reactogenicity through the modulation of factors that control the tumour-immune cell synapse. In this Review, we discuss the interplay between the DDR and anticancer immunity and highlight how this dynamic interaction contributes to shaping tumour immunogenicity. We also review the most innovative preclinical approaches that could be used to investigate such effects, including recently developed ex vivo systems. Finally, we highlight the therapeutic opportunities presented by the exploitation of the DDR-anticancer immunity interplay, with a focus on those in early-phase clinical development.

Inhibiting Lysine Demethylase 1A Improves L1CAM-Specific CAR T Cell Therapy by Unleashing Antigen-Independent Killing via the FAS-FASL Axis

Simple Summary

Solid tumor cells can lose or heterogeneously express antigens to become resistant to chimeric antigen receptor (CAR) T cell therapy. Here, we explore whether epigenetic manipulation to unleash antigen-independent killing mechanisms can overcome this hurdle. KDM1A is overexpressed in many cancers and removes lysine methylation on histones that keeps the DNA firmly packed to selectively activate or repress gene activity, depending on the specific lysine target. KDM1A also regulates the expression of nonhistone proteins. We inhibited KDM1A in the childhood tumor, neuroblastoma, to increase FAS expression on tumor cells. The FAS receptor can be triggered to induce cell death when bound by the FAS ligand on CAR and other activated T cells present in the tumor environment, even if the tumor cells lack the target antigen. FAS upregulation via KDM1A inhibition sensitized neuroblastoma cells to FAS-FASL-mediated killing and augmented CAR T cell therapy against antigen-poor or even antigen-negative neuroblastoma.

Abstract

Chimeric antigen receptor (CAR) T cell therapy has emerged as a promising treatment strategy, however, therapeutic success against solid tumors such as neuroblastoma remains modest. Recurrence of antigen-poor tumor variants often ultimately results in treatment failure. Using antigen-independent killing mechanisms such as the FAS receptor (FAS)-FAS ligand (FASL) axis through epigenetic manipulation may be a way to counteract the escape achieved by antigen downregulation. Analysis of public RNA-sequencing data from primary neuroblastomas revealed that a particular epigenetic modifier, the histone lysine demethylase 1A (KDM1A), correlated negatively with FAS expression. KDM1A is known to interact with TP53 to repress TP53-mediated transcriptional activation of genes, including FAS. We showed that pharmacologically blocking KDM1A activity in neuroblastoma cells with the small molecule inhibitor, SP-2509, increased FAS cell-surface expression in a strictly TP53-dependent manner. FAS upregulation sensitized neuroblastoma cells to FAS-FASL-dependent killing and augmented L1CAM-directed CAR T cell therapy against antigen-poor or even antigen-negative tumor cells in vitro. The improved therapeutic response was abrogated when the FAS-FASL interaction was abolished with an antagonistic FAS antibody. Our results show that KDM1A inhibition unleashes an antigen-independent killing mechanism via the FAS-FASL axis to make tumor cell variants that partially or totally suppress antigen expression susceptible to CAR T cell therapy.

At a Crossroads to Cancer: How p53-Induced Cell Fate Decisions Secure Genome Integrity

P53 is known as the most critical tumor suppressor and is often referred to as the guardian of our genome. More than 40 years after its discovery, we are still struggling to understand all molecular details on how this transcription factor prevents oncogenesis or how to leverage current knowledge about its function to improve cancer treatment. Multiple cues, including DNA-damage or mitotic errors, can lead to the stabilization and nuclear translocation of p53, initiating the expression of multiple target genes. These transcriptional programs may be cell-type- and stimulus-specific, as is their outcome that ultimately imposes a barrier to cellular transformation. Cell cycle arrest and cell death are two well-studied consequences of p53 activation, but, while being considered critical, they do not fully explain the consequences of p53 loss-of-function phenotypes in cancer. Here, we discuss how mitotic errors alert the p53 network and give an overview of multiple ways that p53 can trigger cell death. We argue that a comparative analysis of different types of p53 responses, elicited by different triggers in a time-resolved manner in well-defined model systems, is critical to understand the cell-type-specific cell fate induced by p53 upon its activation in order to resolve the remaining mystery of its tumor-suppressive function.

Fluroxypyr-1-methylheptyl ester interferes with the normal embryogenesis of zebrafish by inducing apoptosis, inflammation, and neurovascular toxicity

Fluroxypyr-1-methylheptyl ester (FPMH) is a synthetic auxin herbicide used to regulate the growth of post-emergence broad-leaved weeds. Although acute exposure to FPMH increases the mortality of several fish species in the juvenile stage, the developmental toxicity of FPMH in aquatic vertebrates has not yet been investigated. In the present study, we assessed the developmental toxicity of FPMH using zebrafish models that offer many advantages for studying toxicology. During embryogenesis, survival rates gradually decreased with increasing FPMH concentrations and exposure times. At 120 h post-fertilization, FPMH-exposed zebrafish larvae showed various abnormalities such as small eye size, heart defects, enlarged yolk sac, and shortened body length. The study results confirmed the induction of apoptosis in the anterior body of zebrafish and upregulation of inflammatory gene expression. Further, defects in vascular networks, especially the loss of central arteries and abnormal aortic arch structures, were seen in the fli1:eGFP transgenic zebrafish model. Neurotoxicity of FPMH was examined using mbp:eGFP zebrafish and which displayed compromised myelination following FPMH administration. Our study has demonstrated the mechanisms underlying FPMH toxicity in developing zebrafish that is a representative model of vertebrates.

Long noncoding RNAs in the regulation of p53-mediated apoptosis in human cancers

Long noncoding RNAs (lncRNAs) are widely known for their regulatory function in transcriptional and posttranscriptional processes. The involvement of such non-protein-coding RNAs in nuclear organization and chromatin remodeling is often associated with an increased risk of human malignancies. In cancer, lncRNAs either promote cell survival or may act as a growth suppressor, thus conferring a key regulatory function other than their established role in fundamental cellular processes. Interestingly, lncRNAs interfere with the stages of apoptosis and related pathways involving p53. Many of these molecules either regulate or are regulated by p53 while mounting oncogenic events. Consequently, they may confer both prosurvival or proapoptotic functions depending upon the tissue type. Since the mechanism of cell death is bypassed in many human cancers, it has emerged that the lncRNAs are either overexpressed or knocked down to sensitize cells to apoptotic stimuli. Nonetheless, the abundant expression of lncRNAs in tumor cells renders them suitable targets for anticancer therapies. Although the role of lncRNAs in the p53 network and apoptosis has been independently defined, their interplay in activating p53-target genes during cell cycle arrest remains unexplored. Thus, we have specifically reviewed the possible involvement of lncRNAs in the p53-mediated apoptosis of human cancer cells. In particular, we summarize the growing evidence from individual studies and analyze whether lncRNAs are essential to facilitate apoptosis in a p53-dependent manner. This may lead to the identification of p53-associated lncRNAs that are suitable therapeutic targets or diagnostic/prognostic markers.

Dying to Survive-The p53 Paradox

The p53 tumour suppressor is best known for its canonical role as "guardian of the genome", activating cell cycle arrest and DNA repair in response to DNA damage which, if irreparable or sustained, triggers activation of cell death. However, despite an enormous amount of work identifying the breadth of the gene regulatory networks activated directly and indirectly in response to p53 activation, how p53 activation results in different cell fates in response to different stress signals in homeostasis and in response to p53 activating anti-cancer treatments remains relatively poorly understood. This is likely due to the complex interaction between cell death mechanisms in which p53 has been activated, their neighbouring stressed or unstressed cells and the local stromal and immune microenvironment in which they reside. In this review, we evaluate our understanding of the burgeoning number of cell death pathways affected by p53 activation and how these may paradoxically suppress cell death to ensure tissue integrity and organismal survival. We also discuss how these functions may be advantageous to tumours that maintain wild-type p53, the understanding of which may provide novel opportunity to enhance treatment efficacy.

High FAS expression correlates with a better prognosis and efficacy of taxanes and target regents in breast cancer

BACKGROUND

FAS can serve as both an oncogene and a suppresser in different malignancies, and the prognostic value of FAS remains controversial.

METHODS

The Oncomine database, KM-Plotter and bc-GenExMiner platform were adopted to analyze the prognostic value of FAS in breast cancer. Breast cancer tissue microarrays were further used to verify these data. The Cell Miner Tool was used to predict the value of FAS mRNA expression in predicting the efficacies of clinical drugs.

RESULTS

We found that both FAS mRNA and protein expression level significantly reduced in breast carcinoma. In addition, high FAS expression indicates a better metastatic relapse-free survival. Interestingly, FAS was associated with a better prognosis in different subtypes of breast cancer patients, namely, only in grade II and III, lymph nodal positive or p53 wild-type patients. The data from the Cell Miner Tool revealed that FAS mRNA expression was correlated with the efficacy of the first-line chemotherapeutic taxane agents and target drugs including olaparib and everolimus.

CONCLUSIONS

FAS expression correlates with a better prognosis in breast cancer and may provide an effective clinical strategy to predict the sensitivity of taxanes and targeted drugs.

Isoforms of the p53 Family and Gastric Cancer: A Ménage à Trois for an Unfinished Affair

Simple Summary

The p53 family is a complex family of transcription factors with different cellular functions that are involved in several physiological processes. A massive amount of data has been accumulated on their critical role in the tumorigenesis and the aggressiveness of cancers of different origins. If common features are observed, there are numerous specificities that may reflect particularities of the tissues from which the cancers originated. In this regard, gastric cancer tumorigenesis is rather remarkable, as it is induced by bacterial and viral infections, various chemical carcinogens, and familial genetic alterations, which provide an example of the variety of molecular mechanisms responsible for cell transformation and how they impact the p53 family. This review summarizes the knowledge gathered from over 40 years of research on the role of the p53 family in gastric cancer, which still displays one of the most elevated mortality rates amongst all types of cancers.

Abstract

Gastric cancer is one of the most aggressive cancers, with a median survival of 12 months. This illustrates its complexity and the lack of therapeutic options, such as personalized therapy, because predictive markers do not exist. Thus, gastric cancer remains mostly treated with cytotoxic chemotherapies. In addition, less than 20% of patients respond to immunotherapy. TP53 mutations are particularly frequent in gastric cancer (±50% and up to 70% in metastatic) and are considered an early event in the tumorigenic process. Alterations in the expression of other members of the p53 family, i.e., p63 and p73, have also been described. In this context, the role of the members of the p53 family and their isoforms have been investigated over the years, resulting in conflicting data. For instance, whether mutations of TP53 or the dysregulation of its homologs may represent biomarkers for aggressivity or response to therapy still remains a matter of debate. This uncertainty illustrates the lack of information on the molecular pathways involving the p53 family in gastric cancer. In this review, we summarize and discuss the most relevant molecular and clinical data on the role of the p53 family in gastric cancer and enumerate potential therapeutic innovative strategies.

REV-ERBα Agonist GSK4112 attenuates Fas-induced Acute Hepatic Damage in Mice

Fas-induced apoptosis is a central mechanism of hepatocyte damage during acute and chronic hepatic disorders. Increasing evidence suggests that circadian clock plays critical roles in the regulation of cell fates. In the present study, the potential significance of REV-ERBα, a core ingredient of circadian clock, in Fas-induced acute liver injury has been investigated. The anti-Fas antibody Jo2 was injected intraperitoneally in mice to induce acute liver injury and the REV-ERBα agonist GSK4112 was administered. The results indicated that treatment of GSK4112 decreased the level of plasma ALT and AST, attenuated the liver histological changes, and promoted the survival rate in Jo2-insulted mice. Treatment with GSK4112 also downregulated the activities of caspase-3 and caspase-8, suppressed hepatocyte apoptosis. In addition, treatment with GSK4112 decreased the level of Fas and enhanced the phosphorylation of Akt. In conclusion, treatment with GSK4112 alleviated Fas-induced apoptotic liver damage in mice, suggesting that REV-ERBα agonist might have potential value in pharmacological intervention of Fas-associated liver injury.

Context is key: Understanding the regulation, functional control, and activities of the p53 tumour suppressor

The p53 tumour suppressor is considered one of the most critical genes in cancer biology. By upregulating apoptosis, cell cycle arrest, and DNA damage repair in normal cells, p53 prevents the propagation of cells with tumorigenic potential; therefore, mutations in p53 are associated with carcinogenic transformation and can be accompanied by the accumulation of a novel gain-of-function oncogenic protein, mutant p53. Although p53 is most often understood to utilize context-dependent post-translational modifications to achieve regulation of its many target genes, recent research has also sought to define other mechanisms of regulating p53 gene expression prior to translation and to understand how this alternative regulation of p53 may influence target gene expression and cellular outcome. This review attempts to summarize what is known about p53 regulation at the transcriptional, post-transcriptional, and post-translational levels while paying special attention to the ways in which context may influence p53 regulation and subsequent regulation of its target genes.