Inhibitors For Cancer Therapy Research Articles

DNA damage response inhibitors in cancer therapy: lessons from the past, current status and future implications.

The DNA damage response (DDR) is a network of proteins that coordinate DNA repair and cell-cycle checkpoints to prevent damage being transmitted to daughter cells. DDR defects lead to genomic instability, which enables tumour development, but they also create vulnerabilities that can be used for cancer therapy. Historically, this vulnerability has been taken advantage of using DNA-damaging cytotoxic drugs and radiotherapy, which are more toxic to tumour cells than to normal tissues. However, the discovery of the unique sensitivity of tumours defective in the homologous recombination DNA repair pathway to PARP inhibition led to the approval of six PARP inhibitors worldwide and to a focus on making use of DDR defects through the development of other DDR-targeting drugs. Here, we analyse the lessons learnt from PARP inhibitor development and how these may be applied to new targets to maximize success. We explore why, despite so much research, no other DDR inhibitor class has been approved, and only a handful have advanced to later-stage clinical trials. We discuss why more reliable predictive biomarkers are needed, explore study design from past and current trials, and suggest alternative models for monotherapy and combination studies. Targeting multiple DDR pathways simultaneously and potential combinations with anti-angiogenic agents or immune checkpoint inhibitors are also discussed.

A Meta-analysis of the Risk of Adverse Cardiovascular Events in Patients with Cancer Treated with Inhibitors of the PI3K/AKT/mTOR Signaling Pathway.

With the increasing of PI3K/AKT/mTOR (PAM) inhibitors in cancer therapy, there is a growing need to understand the incidence of cardiovascular events (CVAEs) associated with PAM inhibitors. A systematic search of all randomized clinical trials (RCTs) containing at least one PAM group in electronic databases such as PubMed, ClinicalTrials.gov registry, Embase, Medline, Cochrane Library, and major conferences was performed to extract available CVAEs. The cut-off date was January 31, 2024. Study heterogeneity was assessed using the I2 statistic. The risk of CVAEs associated with PAM inhibitors was calculated using Peto OR. The primary outcome was the incidence (95% CI) of PAM inhibitors cardiovascular adverse events in the total population and subgroups. The secondary outcome was the pooled risk of different CVAEs associated with PAM inhibitor exposure in the RCTs. 33 unique RCTs (n = 12,351) were included. The incidence of PAM inhibitors CVAEs of any grade in the intervention group was 48.2%, yielding a combined OR of 2.52 (95% CI 1.82-3.49). The incidence of severe adverse cardiovascular events (≥ grade 3) in the intervention group was estimated at 7.1%, yielding a combined Peto OR of 1.41 (95% CI 1.04-1.93). PAM inhibitors were associated with an increased risk of 5 CVAEs including peripheral edema, lymphoedema, hypercholesterolemia, hypertriglyceridaemia and hyperlipidemia, with higher risks for hypercholesterolemia (Peto OR: 3.27,95% CI 2.61-4.11, P < 0.01; I2 = 55.5%, P = 0.06) and hyperlipidemia (Peto OR: 3.53. 95% CI 1.70-7.32, P < 0.01; I2 = 19.3%, P = 0.29). This study identified an overall incidence of PAM inhibitors CVAEs and the increased risks associated with PAM inhibitor for five specific CVAEs, not confined to hypercholesterolemia and peripheral edema.

Immunohistochemical Investigation of Cyclooxygenase-2 Expression in Rabbit Uterine Adenocarcinoma and the Potential Use of COX-2 Inhibitors in Cancer Therapy

Cyclooxygenase-2 (COX-2) is overexpressed in many human and animal cancers. Selective COX-2 inhibitors have shown antitumoral effects in tumors with a high expression of COX-2. This study evaluates (1) the expression of COX-2 in rabbit uterine adenocarcinomas, (2) the correlation between immunophenotypic expression and histopathological changes, and (3) the post-surgery response to therapy with COX-2 inhibitors. Forty rabbit uteri were divided into three groups: neoplastic, hyperplastic, and normal endometrium. A histological and immunohistochemical score was applied to investigate the tumor’s grade and the COX-2 expression. By histological evaluation, 30 cases of endometrial adenocarcinoma, 5 cases of endometrial hyperplasia and 5 normal endometria were found. Of the six cases of endometrial adenocarcinoma with follow-up available, four received a post-surgical treatment with meloxicam and two were treated by surgery alone. The survival time of the animals treated with meloxicam was longer than that observed in the untreated animals. A statistically significant difference in COX-2 IHS was observed between non-neoplastic endometrium and adenocarcinoma. The progressive increase in COX-2 expression from normal epithelium to carcinoma suggests that upregulation of COX-2 expression may play a role in tumor initiation and progression. Our findings suggest the possible use of COX-2 inhibitors in treating uterine adenocarcinoma in rabbits. Further study will be needed to confirm this hypothesis.

Challenges and advances of immune checkpoint therapy

AbstractBackground and ObjectivesImmuno‐checkpoint therapy (ICT) significantly alters the clinical course of cancer patients, providing long‐lasting clinical benefits and offering the potential for cure to some patients. However, response rates for different tumour types vary, and predictive biomarkers are needed to enhance patient selection for the purpose of optimising effectiveness and reducing toxicity. This has driven efforts to decipher the immune and non‐immune factors that regulate ICT response.Main ContentThis review offers a thorough examination of the advantages and future challenges of immune checkpoint inhibitors in cancer therapy. Additionally, we explore ongoing efforts to address current challenges, such as guiding subsequent clinical trials, developing ICT combination therapy strategies and utilising epigenetics to enhance clinical efficacy.Conclusion and PerspectivesDespite significant progress, ICT faces challenges including immune‐related adverse events (irAEs) and resistance mechanisms. Ongoing research focuses on developing novel biomarkers, combination therapies, and epigenetic strategies to improve the efficacy and safety of ICT for cancer patients worldwide. Future studies are required to validate these findings across different tumor types and treatment settings.

Indolo[3,2-c]isoquinoline Hydroxamic Acid Derivatives as Novel Orally Topoisomerase-Histone Deacetylase Dual Inhibitors for NSCLC Therapy.

Based on the synergistic effects of topoisomerase (Top) inhibitors and histone deacetylase (HDAC) inhibitors in cancer therapy, a series of novel Top/HDAC dual inhibitors were designed and synthesized herein. The optimal compound 31 was identified to simultaneously inhibit both Tops and HDACs with potent antiproliferative activity against nonsmall cell lung cancer (NSCLC). Mechanistic studies indicated that compound 31 with increasing reactive oxygen species levels damages DNA, inhibiting cancer cell colony formation and migration and inducing both cancer cell apoptosis and cycle arrest. Noteworthily, compound 31 was orally active in the NSCLC xenograft model, and its antitumor efficacy (TGI = 77.5%, 100 mg/kg) was superior to that of HDAC inhibitor SAHA and SAHA in combination with the Top inhibitor irinotecan. Consequently, this work highlights the therapeutic potential of compound 31 as the Top/HDAC dual inhibitor in NSCLC therapy and provides valuable lead compounds for the further development of antitumor agents in solid tumor therapy.

Poly(ADP-Ribose) Polymerase (PARP) Inhibitors for Cancer Therapy: Advances, Challenges, and Future Directions.

Poly(ADP-ribose) polymerases (PARPs) are crucial nuclear proteins that play important roles in various cellular processes, including DNA repair, gene transcription, and cell death. Among the 17 identified PARP family members, PARP1 is the most abundant enzyme, with approximately 1-2 million molecules per cell, acting primarily as a DNA damage sensor. It has become a promising biological target for anticancer drug studies. Enhanced PARP expression is present in several types of tumors, such as melanomas, lung cancers, and breast tumors, correlating with low survival outcomes and resistance to treatment. PARP inhibitors, especially newly developed third-generation inhibitors currently undergoing Phase II clinical trials, have shown efficacy as anticancer agents both as single drugs and as sensitizers for chemo- and radiotherapy. This review explores the properties, characteristics, and challenges of PARP inhibitors, discussing their development from first-generation to third-generation compounds, more sustainable synthesis methods for discovery of new anti-cancer agents, their mechanisms of therapeutic action, and their potential for targeting additional biological targets beyond the catalytic active site of PARP proteins. Perspectives on green chemistry methods in the synthesis of new anticancer agents are also discussed.

Development and safety of investigational and approved drugs targeting the RAS function regulation in RAS mutant cancers.

The RAS gene family holds a central position in controlling key cellular activities such as migration, survival, metabolism, and other vital biological processes. The activation of RAS signaling cascades is instrumental in the development of various cancers. Although several RAS inhibitors have gained approval from the United States Food and Drug Administration (FDA) for their substantial antitumor effects, their widespread and severe adverse reactions significantly curtail their practical usage in the clinic. Thus, there exists a pressing need for a comprehensive understanding of these adverse events, ensuring the clinical safety of RAS inhibitors through the establishment of precise management guidelines, suitable intermittent dosing schedules, and innovative combination regimens. This review centers on the evolution of RAS inhibitors in cancer therapy, delving into the common adverse effects associated with these inhibitors, their underlying mechanisms, and the potential strategies for mitigation.

Modulation of Tumor Suppressor Genes by Histone Deacetylase Inhibitors in Cancer Therapy

Histone deacetylase (HDAC) inhibitors have emerged as promising therapeutics for various cancers due to their ability to modulate gene expression profiles and restore normal cellular functions. Among the key targets of HDAC inhibitors are tumor suppressor genes, which play crucial roles in regulating cell cycle progression, apoptosis, and DNA repair. However, despite their therapeutic potential, HDAC inhibitors come with significant drawbacks. These include off-target effects that can lead to unintended alterations in gene expression, toxicity to normal cells, and the development of drug resistance in some cancer patients. Additionally, the non-specific nature of some HDAC inhibitors can result in side effects such as fatigue, gastrointestinal disturbances, and hematological toxicity, limiting their clinical utility. This review provides a comprehensive overview of the impact of HDAC inhibitors on tumor suppressor genes in cancer therapy. We discussed the mechanisms by which HDAC inhibitors regulate the expression of tumor suppressor genes, including p53, p21, BRCA1, PTEN, and others, through histone hyperacetylation and chromatin remodeling. Furthermore, we described the therapeutic implications of HDAC inhibitor-induced modulation of tumor suppressor genes in various cancer types, highlighting the potential for combination therapies and personalized treatment approaches. Understanding the interplay between HDAC inhibitors and tumor suppressor genes is critical for optimizing the efficacy of HDAC inhibitor-based therapies and advancing precision medicine in oncology.

Autoimmune complications of tyrosine kinase inhibitors in cancer therapy: Clinical insights, mechanisms, and future perspectives.

The tyrosine kinase inhibitors (TKIs) have emerged as a promising class of novel anticancer drugs, achieving significant success in clinical applications. However, the risk of autoimmune diseases associated with these drugs has raised widespread concerns. In this review, TKI-induced autoimmune diseases are reviewed in order to understand this complex phenomenon through clinical research and molecular mechanism exploration. Despite the relatively low incidence of autoimmune diseases, their potential severity demands heightened attention. The potential mechanisms underlying TKI-induced autoimmune diseases may involve immune system dysregulation, alterations in immune cell function, activation of inflammatory responses, and attacks on self-antigens. Various preventive strategies, including clinical monitoring, personalized treatment, optimization of therapeutic approaches, and patient education and communication, can be employed to effectively address these potential risks. Future research directions should delve into the molecular mechanisms of TKI-induced autoimmune diseases, integrate studies on genetics and immunogenetics, advance the development of novel TKIs, explore the possibilities of combining immunotherapy with TKI treatment, and propel large-scale clinical trials.

The Role of Protein Disulfide Isomerase Inhibitors in Cancer Therapy.

Protein disulfide isomerase (PDI) is a member of the mercaptan isomerase family, primarily located in the endoplasmic reticulum (ER). At least 21 PDI family members have been identified. PDI plays a key role in protein folding, correcting misfolded proteins, and catalyzing disulfide bond formation, rearrangement, and breaking. It also acts as a molecular chaperone. Dysregulation of PDI activity is thus linked to diseases such as cancer, infections, immune disorders, thrombosis, neurodegenerative diseases, and metabolic disorders. In particular, elevated intracellular PDI levels can enhance cancer cell proliferation, metastasis, and invasion, making it a potential cancer marker. Cancer cells require extensive protein synthesis, with disulfide bond formation by PDI being a critical producer. Thus, cancer cells have higher PDI levels than normal cells. Targeting PDI can induce ER stress and activate the Unfolded Protein Response (UPR) pathway, leading to cancer cell apoptosis. This review discusses the structure and function of PDI, PDI inhibitors in cancer therapy, and the limitations of current inhibitors, proposing especially future directions for developing new PDI inhibitors.

PINX1 loss confers susceptibility to PARP inhibition in pan-cancer cells

PARP1 is crucial in DNA damage repair, chromatin remodeling, and transcriptional regulation. The principle of synthetic lethality has effectively guided the application of PARP inhibitors in treating tumors carrying BRCA1/2 mutations. Meanwhile, PARP inhibitors have exhibited efficacy in BRCA-proficient patients, further highlighting the necessity for a deeper understanding of PARP1 function and its inhibition in cancer therapy. Here, we unveil PIN2/TRF1-interacting telomerase inhibitor 1 (PINX1) as an uncharacterized PARP1-interacting protein that synergizes with PARP inhibitors upon its depletion across various cancer cell lines. Loss of PINX1 compromises DNA damage repair capacity upon etoposide treatment. The vulnerability of PINX1-deficient cells to etoposide and PARP inhibitors could be effectively restored by introducing either a full-length or a mutant form of PINX1 lacking telomerase inhibitory activity. Mechanistically, PINX1 is recruited to DNA lesions through binding to the ZnF3-BRCT domain of PARP1, facilitating the downstream recruitment of the DNA repair factor XRCC1. In the absence of DNA damage, PINX1 constitutively binds to PARP1, promoting PARP1-chromatin association and transcription of specific DNA damage repair proteins, including XRCC1, and transcriptional regulators, including GLIS3. Collectively, our findings identify PINX1 as a multifaceted partner of PARP1, crucial for safeguarding cells against genotoxic stress and emerging as a potential candidate for targeted tumor therapy.

Dual Inhibition of SYK and EGFR Overcomes Chemoresistance by Inhibiting CDC6 and Blocking DNA Replication.

Targeting multiple signaling pathways has been proposed as a strategy to overcome resistance to single-pathway inhibition in cancer therapy. A previous study in epithelial ovarian cancers identified hyperactivity of spleen tyrosine kinase (SYK) and epidermal growth factor receptor (EGFR), which mutually phosphorylate and activate each other. Given the potential for pharmacologic inhibition of both kinases with clinically available agents, this study aimed to assess the antitumor efficacy of both pharmacologic and genetic SYK and EGFR co-inhibition using a multifaceted approach to analyze the global phosphoproteome and chemoresistant ovarian cancer cell lines, patient-derived organoids, and xenograft models. Dual inhibition of SYK and EGFR in chemoresistant ovarian cancer cells elicited a highly synergistic antitumor effect. Notably, the combined inhibition strategy activated the DNA damage response, induced G1 cell cycle arrest, and promoted apoptosis. The phosphoproteomic analysis revealed that perturbation of SYK and EGFR signaling induced a significant reduction in both phosphorylated and total protein levels of cell division cycle 6 (CDC6), a crucial initiator of DNA replication. Together, this study offers preclinical evidence supporting dual inhibition of SYK and EGFR as a promising treatment for chemoresistant ovarian cancer that disrupts DNA synthesis by impairing formation of the prereplication complex. These findings warrant further clinical investigation to explore the potential of this combination therapy in overcoming drug resistance and improving patient outcomes.

Expanding the Perspective on PARP1 and Its Inhibitors in Cancer Therapy: From DNA Damage Repair to Immunomodulation.

The emergence of PARP inhibitors as a therapeutic strategy for tumors with high genomic instability, particularly those harboring BRCA mutations, has advanced cancer treatment. However, recent advances have illuminated a multifaceted role of PARP1 beyond its canonical function in DNA damage repair. This review explores the expanding roles of PARP1, highlighting its crucial interplay with the immune system during tumorigenesis. We discuss PARP1's immunomodulatory effects in macrophages and T cells, with a particular focus on cytokine expression. Understanding these immunomodulatory roles of PARP1 not only holds promise for enhancing the efficacy of PARP inhibitors in cancer therapy but also paves the way for novel treatment regimens targeting immune-mediated inflammatory diseases.

Context-dependent roles for autophagy in myeloid cells in tumor progression.

Autophagy is known to suppress tumor initiation by removing genotoxic stresses in normal cells. Conversely, autophagy is also known to support tumor progression by alleviating metabolic stresses in neoplastic cells. Centered on this pro-tumor role of autophagy, there have been many clinical trials to treat cancers through systemic blocking of autophagy. Such systemic inhibition affects both tumor cells and non-tumor cells, and the consequence of blocked autophagy in non-tumor cells in the context of tumor microenvironment is relatively understudied. Here, we examined the effect of autophagy-deficient myeloid cells on the progression of autophagy-competent tumors. We found that blocking autophagy only in myeloid cells modulated tumor progression markedly but such effects were context dependent. In a tumor implantation model, the growth of implanted tumor cells was substantially reduced in mice with autophagy-deficient myeloid cells; T cells infiltrated deeper into the tumors and were responsible for the reduced growth of the implanted tumor cells. In an oncogene-driven tumor induction model, however, tumors grew faster and metastasized more in mice with autophagy-deficient myeloid cells. These data demonstrate that the autophagy status of myeloid cells plays a critical role in tumor progression, promoting or suppressing tumor growth depending on the context of tumor-myeloid cell interactions. This study indicates that systemic use of autophagy inhibitors in cancer therapy may have differential effects on rates of tumor progression in patients due to effects on myeloid cells and that this warrants more targeted use of selective autophagy inhibitors in a cancer therapy in a clinical setting.

The Drosophila histone methyltransferase SET1 coordinates multiple signaling pathways in regulating male germline stem cell maintenance and differentiation.

Many tissue-specific adult stem cell lineages maintain a balance between proliferation and differentiation. Here, we study how the H3K4me3 methyltransferase Set1 regulates early-stage male germ cells in Drosophila. Early-stage germline-specific knockdown of Set1 results in temporally progressive defects, arising as germ cell loss and developing into overpopulated early-stage germ cells. These germline defects also impact the niche architecture and cyst stem cell lineage non-cell-autonomously. Additionally, wild-type Set1, but not the catalytically inactive Set1, rescues the Set1 knockdown phenotypes, highlighting the functional importance of the methyltransferase activity of Set1. Further, RNA-sequencing experiments reveal key signaling pathway components, such as the JAK-STAT pathway gene Stat92E and the BMP pathway gene Mad, which are upregulated upon Set1 knockdown. Genetic interaction assays support the functional relationships between Set1 and JAK-STAT or BMP pathways, as both Stat92E and Mad mutations suppress the Set1 knockdown phenotypes. These findings enhance our understanding of the balance between proliferation and differentiation in an adult stem cell lineage. The phenotype of germ cell loss followed by over-proliferation when inhibiting a histone methyltransferase also raises concerns about using their inhibitors in cancer therapy.

Camptothecin and its Analogues as Putative Bruton Tyrosine Kinase (BTK) Inhibitors in Cancer Therapy - Biophysical Simulations of Wild Type and C481S Mutation

Camptothecin (CPT) and its derivatives are extracted from the Chinese tree Camptotheca acuminata and have been long known for their significant antitumor activity. The widely reported primary mechanism of their anti-cancer activity is through inhibition of topoisomerase I (Topo I), a key anticancer target. However, there is a lack of research on other possible mechanisms of action of CPT and its analogues (CPT/analogues). In this report, we investigated the potential inhibitory mechanism of CPT/derivatives against Bruton’s tyrosine kinase (BTK) ‒ a crucial protein for regulating various cellular functions and is essential for B-cell growth and cyclical division. The binding mechanism of CPT and its analogues (Irinotecan, Diflomotecan, and Topotecan) against BTK was investigated using molecular docking, molecular dynamics simulations and thermodynamic binding free energy calculations. NRX-0492, a potent orally active degrader of both wild-type and mutant BTK, was used as a reference/control inhibitor. We also included a set of active binders (actives) and non-binders (inactives) to distinguish between effective binders and false positives to ensure the validity of our results. Binding affinity analysis suggested that CPT and its analogues could potentially bind to BTK comparably to NRX-0492. The studied compounds demonstrated stable binding with the protein throughout the simulation time via hydrogen bonds, π-π interactions, van der Waals forces and π-sulfur interactions. Irinotecan exhibited a binding affinity of ΔGbinding = –42.4±5.3 kcal/mol, closely matching that of NRX-0492 (ΔGbinding = –48.8±3.4 kcal/mol). Furthermore, the activity of CPT/derivatives was examined against the C481S mutant. Although the activity was slightly decreased due to the mutation, the compounds retained a promising binding affinity when compared to the results of NRX-0492. The findings of this study provide foundation for future experimental investigation of unexplored potential anti-cancer mechanism of CPT/derivatives and offer a new perspective on repurposing of natural products in cancer therapy.

Gp93 inhibits unfolded protein response-mediated c-Jun N-terminal kinase activation and cell invasion.

In eukaryotes, Hsp90B1 serves as a vital chaperonin, facilitating the accurate folding of proteins. Interestingly, Hsp90B1 exhibits contrasting roles in the development of various types of cancers, although the underlying reasons for this duality remain enigmatic. Through the utilization of the Drosophila model, this study unveils the functional significance of Gp93, the Drosophila ortholog of Hsp90B1, which hitherto had limited reported developmental functions. Employing the Drosophila cell invasion model, we elucidated the pivotal role of Gp93 in regulating cell invasion and modulating c-Jun N-terminal kinase (JNK) activation. Furthermore, our investigation highlights the involvement of the unfolded protein response-associated IRE1/XBP1 pathway in governing Gp93 depletion-induced, JNK-dependent cell invasion. Collectively, these findings not only uncover a novel molecular function of Gp93 in Drosophila, but also underscore a significant consideration pertaining to the testing of Hsp90B1 inhibitors in cancer therapy.

Recent Progress of Glutathione Peroxidase 4 Inhibitors in Cancer Therapy.

Ferroptosis is a novel type of programmed cell death that relies on the build-up of intracellular iron and leads to an increase in toxic lipid peroxides. Glutathione Peroxidase 4 (GPX4) is a crucial regulator of ferroptosis that uses glutathione as a cofactor to detoxify cellular lipid peroxidation. Targeting GPX4 in cancer could be a promising strategy to induce ferroptosis and kill drugresistant cancers effectively. Currently, research on GPX4 inhibitors is of increasing interest in the field of anti-tumor agents. Many reviews have summarized the regulation and ferroptosis induction of GPX4 in human cancer and disease. However, insufficient attention has been paid to GPX4 inhibitors. This article outlines the molecular structures and development prospects of GPX4 inhibitors as novel anticancer agents.

Virtual Screening, Molecular Docking, and Molecular Dynamics Simulation Studies on Potential Phytochemicals as Sphingosine Kinase 1 Inhibitors for Cancer Therapy

Sphingosine kinases (SphKs) as lipid kinases catalyze the phosphorylation of sphingosine (Sph) to sphingosine-1-phosphate (S1P). Targeting the S1P signaling pathway is a significant strategy for many human diseases. Herein, we evaluated main prenylated bioactive components of a medicinal plant and performed a virtual screening study with flavonoid compounds and then, molecular docking and molecular dynamics (MD) simulation for the targeted cancer therapy. In silico ADMET and drug-likeness results were determined by BIOVIA Discovery Studio (DS). Molecular docking and molecular dynamics (MD) simulations were carried out by using Glide/SP and Desmond of Maestro with the filtered ligands. Glide/SP docking results showed higher binding affinity with xanthohumol (XN), 8-prenylnaringenin (8-PN), and neobavaisoflavone against SphK1. Three hits displayed strong hydrogen binding between the specific amino acid residues of targeting SphK1. There were no significant structural changes between SphK1-XN and SphK1-neobavaisoflavone complexes during 200 ns MD simulation analysis performed by GROMACS. Root-mean square deviation (RMSD) average values of XN- and neobavaisoflavone-protein complexes were compared to free SphK1 and were found as 0.2626 nm, 0.2589 nm, and 0.2508 nm, respectively. As a result, XN and 8-PN, and neobavaisoflavone have been determined as potential inhibitor candidates of SphK1 to examine for further in vitro and in vivo studies.

Role of natural secondary metabolites as HIF-1 inhibitors in cancer therapy

Role of natural secondary metabolites as HIF-1 inhibitors in cancer therapy