Review of poly (ADP-ribose) polymerase (PARP) mechanisms of action and rationale for targeting in cancer and other diseases

Characterization of PARP1 binding to c-KIT1 G-quadruplex DNA: Insights into domain-specific interactions

Poly(ADP-ribose) polymerase 1 (PARP1) is a nuclear enzyme involved in catalyzing Poly-(ADP-ribosyl)ation. PARP1 binds to different forms of DNA and DNA breaks and thus plays important roles in several cellular processes, including DNA damage repair, cell cycle regulation, chromatin remodeling, and maintaining genomic stability. In this study, we conducted biochemical and biophysical characterization of PARP1 binding to G-quadruplex DNA (G4-DNA). Our investigation identified ZnF1, ZnF3, and WGR as the critical domains to mediate PARP1 binding to G4-c-KIT1. Also, our results show that these domains together show cooperativity for G4-c-KIT1 recognition. Further, we establish that the presence of an oxidized (5-carboxylcytosine) base in the loop region of G4-c-KIT1 (G4-5caC-cKIT1) does not affect its recognition by PARP1. Both G4-c-KIT1 and G4-5caC-cKIT1 are potent stimulators of PARP1's catalytic activity. Our study advances the understanding of PARP1's versatile DNA binding capabilities for G4-c-KIT1 DNA irrespective of the oxidation/ modification in the DNA base. These insights into PARP1's domain-specific contributions to G4-c-KIT1 DNA recognition and catalysis expand our knowledge of its multifaceted roles in DNA repair and genome maintenance.

PARP inhibitors in ovarian cancer: Mechanisms, resistance, and the promise of combination therapy

Current approaches to treating ovarian cancer focus mainly on surgical cytoreduction and chemotherapy using platinum-based drugs, while newer methods such as immunotherapy are being investigated to enhance treatment outcomes. Treating ovarian cancer is complicated by challenges such as late-stage detection, tumor diversity, and limited treatment choices. Therefore, innovative strategies such as precision medicine and targeted therapies like PARPi (Poly ADP-Ribose Polymerase inhibitors) are increasingly necessary. The article highlights the significance of an innovative therapeutic approach focusing on PARPi in revolutionizing ovarian cancer treatment and improving patient outcomes. It covers the basic knowledge of PARP, its structure, and its function in DNA repair. It further emphasizes how inhibiting PARP can help in treating ovarian cancer. It elaborates on the mechanism of action of PARPi. It covers the clinical trials governing PARPi and the combination of drugs used with PARPi. It mentions how the resistance is developed to PARPi and the strategies to overcome the resistance developed.

Melatonin and brain barriers: The protection conferred by melatonin to the blood-brain barrier and blood-cerebrospinal fluid barrier

The blood-brain barrier and the blood-cerebrospinal fluid barrier separate the blood from brain tissue and cerebrospinal fluid. These brain barriers are important to maintain homeostasis and complex functions by protecting the brain from xenobiotics and harmful endogenous compounds. The disruption of brain barriers is a characteristic of neurologic diseases. Melatonin is a lipophilic hormone that is mainly produced by the pineal gland. The blood-brain barrier and the blood-cerebrospinal fluid barriers are melatonin-binding sites. Among the several melatonin actions, the most characteristic one is the regulation of sleep-wake cycles, melatonin has anti-inflammatory and antioxidant properties. Since brain barriers disruption can arise from inflammation and oxidative stress, knowing the influence of melatonin on the integrity of brain barriers is extremely important. Therefore, the objective of this review is to gather and discuss the available literature about the regulation of brain barriers by melatonin.

Nuclear localization of APLF facilitates breast cancer metastasis

Most breast cancer deaths result from metastases. We previously reported that DNA repair factor and histone chaperone Aprataxin PNK-like Factor (APLF) is involved in EMT-associated metastasis of triple negative breast cancer (TNBC) cells. However, non-metastatic cells also expressed APLF, the implications of which in disease advancement remain uncertain. Here, we demonstrate that the metastatic prognosis of breast cancer cells may be determined by the cellular localization of APLF. Using TNBC patient samples and cell lines, we discovered that APLF was localized in the nucleus and cytoplasm, whereas other subtypes of breast cancer had cytosolic or perinuclear localization. To investigate metastatic properties in vitro and in vivo, we modeled APLF differential localization by stably producing APLF-tagged nuclear localization signal (NLS) in the luminal subtype MCF7 cells in the absence of putative APLF NLS. Nuclear APLF in non-metastatic MCF7 cells demonstrated pronounced migration, invasion and metastatic potential. We obtained the mechanistic insight from molecular studies that PARP1 could facilitate the transport of APLF from the cytosol to the nucleus, assisting in the metastasis of TNBC cells linked with EMT. Inhibition of PARP1 enzymatic activity with olaparib abrogated the nuclear expression of APLF with loss in expression of genes associated with EMT. Thus, our findings reveal that cellular localization of APLF may predict the risk of breast cancer to metastasize and hence could be exploited to determine the disease progression. We anticipate that the inhibition of cytosolic PARP1-APLF interaction may potentially aid in the prevention of breast cancer metastasis in TNBC patients.

The role of nonesterified fatty acids in cancer biology: Focus on tryptophan and related metabolism

Plasma nonesterified fatty acids (NEFA) are elevated in cancer, because of decreased albumin levels and of fatty acid oxidation, and increased fatty acid synthesis and lipolysis. Albumin depletion and NEFA elevation maximally release albumin-bound tryptophan (Trp) and increase its flux down the kynurenine pathway, leading to increased production of proinflammatory kynurenine metabolites, which tumors use to undermine T-cell function and achieve immune escape. Activation of the aryl hydrocarbon receptor by kynurenic acid promotes extrahepatic Trp degradation by indoleamine 2,3-dioxygenase and leads to upregulation of poly (ADP-ribose) polymerase, activation of which and also of SIRT1 (silent mating type information regulation 2 homolog 1) could lead to depletion of NAD+ and ATP, resulting in cell death. NEFA also modulate heme synthesis and degradation, changes in which impact homocysteine metabolism and production of reduced glutathione and hydrogen sulphide. The significance of the interactions between heme and homocysteine metabolism in cancer biology has received little attention. Targeting Trp disposition in cancer to prevent the NEFA effects is suggested.

Exploiting mechanoregulation via FAK/YAP to overcome platinum resistance in ovarian cancer

Cancer cells mechanically interact with the tumor microenvironment during cancer development. Mechano-reciprocity has emerged as a crucial factor affecting anti-cancer drug resistance during adjuvant therapy. Here, we investigated the focal adhesion kinase (FAK)/Yes-associated protein (YAP) signaling axis as a prospective strategy for circumventing cisplatin resistance in ovarian cancer (OC). The Cancer Genome Atlas (TCGA) data analysis revealed that FAK overexpression significantly correlated with unfavorable clinical outcomes in patients with ovarian cancer. AFM indentation experiments showed that cell elasticity depends on FAK activity. Notably, the combination of FAK inhibition and cisplatin treatment led to a 69 % reduction in the IC50 of cisplatin. This combined treatment also increased apoptosis compared to the individual treatments, along with the upregulation of the pro-apoptotic factor BAX and cleaved PARP. Suppressing FAK expression sequestered YAP in the cytosol, potentially reducing cellular proliferation and promoting apoptosis. Moreover, reduced FAK expression sensitized drug-resistant OC cells to cisplatin treatment owing to a decrease in nuclear tension, allowing the relocation of YAP to the cytosol. In a mouse model, the co-administration of an FAK inhibitor and cisplatin significantly suppressed tumor growth and increased apoptotic events and DNA fragmentation. Our findings suggest that drug resistance can be attributed to the perturbation of mechanosensing signaling pathways, which drive the mechanical reinforcement of cancer cells. OC cells can restore their sensitivity to cisplatin treatment by strategically reducing YAP localization in the nucleus through FAK downregulation.

Strategies for the prevention or reversal of PARP inhibitor resistance

INTRODUCTION

Advances in our understanding of tumor biology shed light on hallmarks of cancer development and progression that include dysregulated DNA damage repair (DDR) machinery. Leveraging the underlying tumor genomic instability and tumor-specific defects in DDR, Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) induced DNA damage emerges as a novel non-chemotherapy therapeutic opportunity. PARPis are currently approved in multiple tumor types, with the largest benefit seen in tumors with homologous recombination repair (HRR) deficiency, including germline and somatic mutations in BRCA1/2 genes (BRCA) and other pathway members such as PALB2 and Rad51c.

AREAS COVERED

This review article summarizes the current approval landscape and known and proposed mechanisms of resistance to PARPi. Further, therapeutic strategies to overcome PARPi resistance are discussed, including ongoing clinical trials.

EXPERT OPINION

PARPi have proven to be a safe and effective therapy and represents a cornerstone treatment across multiple solid tumor types. Elucidating innate and acquired mechanisms of resistance, coupled with the emergence of novel therapeutic options to capitalize on the activity of PARPi and prevent or reverse the acquisition of resistance, provides an opportunity to further expand the role of PARPi in cancer therapy.

Poly ADP-ribose signaling is dysregulated in Huntington disease

Huntington disease (HD) is a genetic neurodegenerative disease caused by cytosine, adenine, guanine (CAG) expansion in the Huntingtin (HTT) gene, translating to an expanded polyglutamine tract in the HTT protein. Age at disease onset correlates to CAG repeat length but varies by decades between individuals with identical repeat lengths. Genome-wide association studies link HD modification to DNA repair and mitochondrial health pathways. Clinical studies show elevated DNA damage in HD, even at the premanifest stage. A major DNA repair node influencing neurodegenerative disease is the PARP pathway. Accumulation of poly adenosine diphosphate (ADP)-ribose (PAR) has been implicated in Alzheimer and Parkinson diseases, as well as cerebellar ataxia. We report that HD mutation carriers have lower cerebrospinal fluid PAR levels than healthy controls, starting at the premanifest stage. Human HD induced pluripotent stem cell-derived neurons and patient-derived fibroblasts have diminished PAR response in the context of elevated DNA damage. We have defined a PAR-binding motif in HTT, detected HTT complexed with PARylated proteins in human cells during stress, and localized HTT to mitotic chromosomes upon inhibition of PAR degradation. Direct HTT PAR binding was measured by fluorescence polarization and visualized by atomic force microscopy at the single molecule level. While wild-type and mutant HTT did not differ in their PAR binding ability, purified wild-type HTT protein increased in vitro PARP1 activity while mutant HTT did not. These results provide insight into an early molecular mechanism of HD, suggesting possible targets for the design of early preventive therapies.

Urdamycin V from Streptomyces sp induces p53 independent apoptosis in cervical cancer cells inconsiderate of HPV status and inhibited growth of gram-positive human pathogens

In cervical cancer, loss of p53 or mutant non-functional p53 and hyperactivated mTOR/Akt pathway positively correlates to cancer progression. Urdamycin V isolated from Streptomyces OA293 is a recently isolated novel angucycline derivative that in the present study showcased induction of p53 independent apoptosis in both HPV (Human papillomavirus) positive and negative cervical cancer cell lines. Apoptosis induction was via phosphorylation modulation in the cell growth regulating proteins along mTORC2/Akt/p38/Erk pathway. The compound was also tested against human pathogens and selectively inhibited gram-positive strains, Streptococcus pyogenes and Staphylococcus aureus. The present study put forward urdamycins as a potential therapeutic that places promise for further research.

Steroidal constituents in the whole plants of Helleborus niger and their cytotoxic activity in vitro

Phytochemical investigation of the whole plants of Helleborus niger L. (Ranunculaceae) resulted in the isolation of five undescribed compounds, including one bufadienolide (1), two bufadienolide rhamnosides (2 and 3), and two ecdysteroids (12 and 13), along with eight known compounds (4-11). The chemical structures of 1-3, 12, and 13 were determined by spectroscopic studies, including 2D NMR, and chromatographic and spectroscopic analyses of the hydrolyzed products. Compounds 1-13 were evaluated for their cytotoxic activity against HL-60 human leukemia cells, A549 human lung adenocarcinoma cells, SBC-3 human small-cell lung cancer cells, and TIG-3 human normal diploid lung cells. Compounds 1-12 showed cytotoxic activity against HL-60, A549, and SBC-3 cells, with IC50 values ranging from 0.0016 to 6.1 μM. Bufadienolide rhamnoside 2 exhibited potent cell proliferation inhibitory activity against SBC-3 cells after 24-48 h of treatment and apoptosis-inducing activity in SBC-3 cells via an intrinsic pathway after 72 h of treatment. The JFCR39 panel screening of 2 suggests that the molecular target of 2 is Na+,K+-ATPase.

PARP-1 selectively impairs KRAS-driven phenotypic and molecular features in intrahepatic cholangiocarcinoma

OBJECTIVE

Intrahepatic cholangiocarcinoma (iCCA) is the second most common primary liver cancer with limited therapeutic options. KRAS mutations are among the most abundant genetic alterations in iCCA associated with poor clinical outcome and treatment response. Recent findings indicate that Poly(ADP-ribose)polymerase1 (PARP-1) is implicated in KRAS-driven cancers, but its exact role in cholangiocarcinogenesis remains undefined.

DESIGN

PARP-1 inhibition was performed in patient-derived and established iCCA cells using RNAi, CRISPR/Cas9 and pharmacological inhibition in KRAS-mutant, non-mutant cells. In addition, Parp-1 knockout mice were combined with iCCA induction by hydrodynamic tail vein injection to evaluate an impact on phenotypic and molecular features of Kras-driven and Kras-wildtype iCCA. Clinical implications were confirmed in authentic human iCCA.

RESULTS

PARP-1 was significantly enhanced in KRAS-mutant human iCCA. PARP-1-based interventions preferentially impaired cell viability and tumourigenicity in human KRAS-mutant cell lines. Consistently, loss of Parp-1 provoked distinct phenotype in Kras/Tp53-induced versus Akt/Nicd-induced iCCA and abolished Kras-dependent cholangiocarcinogenesis. Transcriptome analyses confirmed preferential impairment of DNA damage response pathways and replicative stress response mediated by CHK1. Consistently, inhibition of CHK1 effectively reversed PARP-1 mediated effects. Finally, Parp-1 depletion induced molecular switch of KRAS-mutant iCCA recapitulating good prognostic human iCCA patients.

CONCLUSION

Our findings identify the novel prognostic and therapeutic role of PARP-1 in iCCA patients with activation of oncogenic KRAS signalling.

Biological Functions and Therapeutic Potential of NAD+ Metabolism in Gynecological Cancers

Nicotinamide adenine dinucleotide (NAD+) is an important cofactor for both metabolic and signaling pathways, with the dysregulation of NAD+ levels acting as a driver for diseases such as neurodegeneration, cancers, and metabolic diseases. NAD+ plays an essential role in regulating the growth and progression of cancers by controlling important cellular processes including metabolism, transcription, and translation. NAD+ regulates several metabolic pathways such as glycolysis, the citric acid (TCA) cycle, oxidative phosphorylation, and fatty acid oxidation by acting as a cofactor for redox reactions. Additionally, NAD+ acts as a cofactor for ADP-ribosyl transferases and sirtuins, as well as regulating cellular ADP-ribosylation and deacetylation levels, respectively. The cleavage of NAD+ by CD38-an NAD+ hydrolase expressed on immune cells-produces the immunosuppressive metabolite adenosine. As a result, metabolizing and maintaining NAD+ levels remain crucial for the function of various cells found in the tumor microenvironment, hence its critical role in tissue homeostasis. The NAD+ levels in cells are maintained by a balance between NAD+ biosynthesis and consumption, with synthesis being controlled by the Preiss-Handler, de novo, and NAD+ salvage pathways. The primary source of NAD+ synthesis in a variety of cell types is directed by the expression of the enzymes central to the three biosynthesis pathways. In this review, we describe the role of NAD+ metabolism and its synthesizing and consuming enzymes' control of cancer cell growth and immune responses in gynecologic cancers. Additionally, we review the ongoing efforts to therapeutically target the enzymes critical for NAD+ homeostasis in gynecologic cancers.

Application of Nanotechnology and Phytochemicals in Anticancer Therapy

Cancer is well recognized as a leading cause of mortality. Although surgery tends to be the primary treatment option for many solid cancers, cancer surgery is still a risk factor for metastatic diseases and recurrence. For this reason, a variety of medications has been adopted for the postsurgical care of patients with cancer. However, conventional medicines have shown major challenges such as drug resistance, a high level of drug toxicity, and different drug responses, due to tumor heterogeneity. Nanotechnology-based therapeutic formulations could effectively overcome the challenges faced by conventional treatment methods. In particular, the combined use of nanomedicine with natural phytochemicals can enhance tumor targeting and increase the efficacy of anticancer agents with better solubility and bioavailability and reduced side effects. However, there is limited evidence in relation to the application of phytochemicals in cancer treatment, particularly focusing on nanotechnology. Therefore, in this review, first, we introduce the drug carriers used in advanced nanotechnology and their strengths and limitations. Second, we provide an update on well-studied nanotechnology-based anticancer therapies related to the carcinogenesis process, including signaling pathways related to transforming growth factor-β (TGF-β), mitogen-activated protein kinase (MAPK), phosphatidylinositol 3 kinase (PI3K), Wnt, poly(ADP-ribose) polymerase (PARP), Notch, and Hedgehog (HH). Third, we introduce approved nanomedicines currently available for anticancer therapy. Fourth, we discuss the potential roles of natural phytochemicals as anticancer drugs. Fifth, we also discuss the synergistic effect of nanocarriers and phytochemicals in anticancer therapy.

Clinical relevance of double heterozygosity revealed by next-generation sequencing of homologous recombination repair pathway genes in South African breast cancer patients

PURPOSE

Genetically predisposed breast cancer (BC) patients represent a minor but clinically meaningful subgroup of the disease, with 25% of all cases associated with actionable variants in BRCA1/2. Diagnostic implementation of next-generation sequencing (NGS) resulted in the rare identification of BC patients with double heterozygosity for deleterious variants in genes partaking in homologous recombination repair of DNA. As clinical heterogeneity poses challenges for genetic counseling, this study focused on the occurrence and clinical relevance of double heterozygous BC in South Africa.

METHODS

DNA samples were diagnostically screened using the NGS-based Oncomine™ BRCA Expanded Research Assay. Data was generated on the Ion GeneStudio S5 system and analyzed using the Torrent Suite™ and reporter software. The clinical significance of the variants detected was determined using international variant classification guidelines and treatment implications.

RESULTS

Six of 1600 BC patients (0.375%) tested were identified as being bi-allelic for two germline likely pathogenic or pathogenic variants. Most of the variants were present in BRCA1/2, including two founder-related small deletions in three cases, with family-specific variants detected in ATM, BARD1, FANCD2, NBN, and TP53. The scientific interpretation and clinical relevance were based on the clinical and tumor characteristics of each case.

CONCLUSION

This study increased current knowledge of the risk implications associated with the co-occurrence of more than one pathogenic variant in the BC susceptibility genes, confirmed to be a rare condition in South Africa. Further molecular pathology-based studies are warranted to determine whether clinical decision-making is affected by the detection of a second pathogenic variant in BRCA1/2 and TP53 carriers.

Neoadjuvant talazoparib in patients with germline BRCA1/2 mutation-positive, early-stage triple-negative breast cancer: exploration of tumor BRCA mutational status

BACKGROUND

Talazoparib monotherapy in patients with germline BRCA-mutated, early-stage triple-negative breast cancer (TNBC) showed activity in the neoadjuvant setting in the phase II NEOTALA study (NCT03499353). These biomarker analyses further assessed the mutational landscape of the patients enrolled in the NEOTALA study.

METHODS

Baseline tumor tissue from the NEOTALA study was tested retrospectively using FoundationOne®CDx. To further hypothesis-driven correlative analyses, agnostic heat-map visualizations of the FoundationOne®CDx tumor dataset were used to assess overall mutational landscape and identify additional candidate predictive biomarkers of response.

RESULTS

All patients enrolled (N = 61) had TNBC. In the biomarker analysis population, 75.0% (39/52) and 25.0% (13/52) of patients exhibited BRCA1 and BRCA2 mutations, respectively. Strong concordance (97.8%) was observed between tumor BRCA and germline BRCA mutations, and 90.5% (38/42) of patients with tumor BRCA mutations evaluable for somatic-germline-zygosity were predicted to exhibit BRCA loss of heterozygosity (LOH). No patients had non-BRCA germline DNA damage response (DDR) gene variants with known/likely pathogenicity, based on a panel of 14 non-BRCA DDR genes. Ninety-eight percent of patients had TP53 mutations. Genomic LOH, assessed continuously or categorically, was not associated with response.

CONCLUSION

The results from this exploratory biomarker analysis support the central role of BRCA and TP53 mutations in tumor pathobiology. Furthermore, these data support assessing germline BRCA mutational status for molecular eligibility for talazoparib in patients with TNBC.

Poly (Adp-Ribose) Polymerase-1 (PARP-1) Is a Good Prognostic Marker for Pancreatic/Periampullary Cancers

BACKGROUND

Periampullary cancer (PAC) is highly aggressive with no effective adjuvant therapy or prognostic markers. Recently, poly (ADP-ribose) polymerase-1 (PARP-1) has emerged as a target in solid cancers, and its relationship with epithelial-mesenchymal transition (EMT) has been observed. However, the relationship between PARP-1 and EMT in PAC has not explored well.

MATERIALS AND METHODS

We assessed the prognostic significance of PARP-1 in 190 PACs patients and correlated it with EMT markers, including FGF8, FGFR4, MMP2, MMP3, Snail, and ZEB1. Immunohistochemistry for PARP-1 and EMT markers was performed using a tissue microarray.

RESULTS

PARP-1 and FGF8 expression were associated with better survival unlike other solid cancers ( P = 0.006 and P = 0.003), and MMP3 and ZEB1 expression were associated with poor prognosis in multivariate and survival analyses ( P = 0.009 and P < 0.001). In addition, PARP-1 is related negatively to Snail but not related with other EMT markers, implying an independent mechanism between PARP-1 and EMT in PACs. PARP-1 and FGF8 are independent good survival markers in PACs unlike other solid cancers.

CONCLUSIONS

PARP-1 and FGF8 in PACs could not be related to the EMT pathway but must be rather understood in light of similar cancer-protective roles. Further studies are required on EMT-associated immune markers in PACs.

Efficacy of chemotherapy after progression during or following PARPi exposure in ovarian cancer

BACKGROUND

Poly(ADP-ribose) polymerase inhibitors (PARPis) improved advanced ovarian cancer treatment. Most patients progress during or following PARPi exposure, however, with concerns about sensitivity of subsequent chemotherapy.

PATIENTS AND METHODS

In this international cohort study, we evaluated the efficacy of a subsequent chemotherapy following PARPi exposure in high-grade ovarian carcinoma patients. Endpoints included progression-free survival (PFS), overall survival and a multivariable Cox model was built to identify factors influencing PFS.

RESULTS

We included 291 patients from four international centers treated between January 2002 and December 2021. The median number of previous chemotherapy was 1 (1.0-7.0), the median duration of PARPi exposure was 6.5 months (0.2-54.3 months). PARPi was used in first line in 14.1% patients. Most progressions occurred under PARPi exposure (89.1%). A BRCA pathogenic variant was identified in 130 patients (44.7%), absent in 157 patients (54.0%), and undocumented in 4 patients (1.4%). Platinum-based CT (PBC) and non-PBC were administered as subsequent treatments in, respectively, 182 patients (62.5%) and 109 patients (37.5%). Multivariable analyses showed that platinum-free interval (PFI) >6 months [adjusted hazards ratio (HR), 0.52; 95% confidence interval (CI) 0.39-0.70] and type of initial surgery (adjusted HR, 1.41; 95% CI 1.07-1.87; interval or closing surgery versus primary surgery) were associated with PFS, independent of BRCA status or line of therapy (≥2 versus 1). In patients with a PFI >6 months, PBC was numerically associated with the best PFS (adjusted HR, 0.68; 95% CI 0.46-1.01).

CONCLUSION

This is the largest real-world study assessing the efficacy of subsequent chemotherapy in patients progressing during PARPi exposure. The patients have poor outcomes. PBC is the best option in patients progressing on PARPi and eligible for PBC rechallenge (PFI >6 months).

Poly(Adenosine Diphosphate Ribose) Polymerase (PARP) Inhibitors in the Treatment of Advanced Ovarian Cancer: A Narrative Review

Poly(adenosine diphosphate ribose) polymerase (PARP) inhibitors have appeared as a revolutionary approach to treating advanced ovarian cancer, particularly in patients with breast cancer (BRCA) mutations and homologous recombination deficiency (HRD). This narrative review explores PARP inhibitors' clinical efficiency, safety, and changing role in this context. PARP inhibitors, such as olaparib, niraparib, or rucaparib, provide considerable benefits regarding progression-free survival expansion and overall outcomes improvement in first-line maintenance and recurrent settings. The underlying mechanisms, patient selection criteria, and resistance patterns are discussed, alongside insights into combination therapies to overcome resistance and enhance therapeutic efficacy. Ongoing clinical trials and future potential for personalized therapy approaches using PARP inhibitors for advanced ovarian cancer are also highlighted. However, despite these drugs' phenomenal ability to revolutionize treatment protocols for such cancer types, several challenges remain: toxicity management, cost, and development of resistance will require more research to optimize their use or broaden patient populations who can benefit from them.

Effects of long-term dehydration and quick rehydration on the camel kidney: pathological changes and modulation of the expression of solute carrier proteins and aquaporins

BACKGROUND

Recurrent dehydration causes chronic kidney disease in humans and animal models. The dromedary camel kidney has remarkable capacity to preserve water and solute during long-term dehydration. In this study, we investigated the effects of dehydration and subsequent rehydration in the camel's kidney histology/ultrastructure and changes in aquaporin/solute carrier proteins along with gene expression.

RESULTS

In light microscopy, dehydration induced few degenerative and necrotic changes in cells of the cortical tubules with unapparent or little effect on medullary cells. The ultrastructural changes encountered in the cortex were infrequent during dehydration and included nuclear chromatin condensation, cytoplasmic vacuolization, mitochondrial swelling, endoplasmic reticulum/ lysosomal degeneration and sometimes cell death. Some mRNA gene expressions involved in cell stability were upregulated by dehydration. Lesions in endothelial capillaries, glomerular membranes and podocyte tertiary processes in dehydrated camels indicated disruption of glomerular filtration barrier which were mostly corrected by rehydration. The changes in proximal tubules brush borders after dehydration, were accompanied by down regulation of ATP1A1 mRNA involved in Na + /K + pump that were corrected by rehydration. The increased serum Na, osmolality and vasopressin were paralleled by modulation in expression level for corresponding SLC genes with net Na retention in cortex which were corrected by rehydration. Medullary collecting ducts and interstitial connective tissue were mostly unaffected during dehydration. CKD, a chronic nephropathy induced by recurrent dehydration in human and animal models and characterized by interstitial fibrosis and glomerular sclerosis, were not observed in the dehydrated/rehydrated camel kidneys. The initiating factors, endogenous fructose, AVP/AVPR2 and uric acid levels were not much affected. TGF-β1 protein and TGF-β1gene expression showed no changes by dehydration in cortex/medulla to mediate fibrosis. KCNN4 gene expression level was hardly detected in the dehydrated camel's kidney; to encode for Ca +  + -gated KCa3.1 channel for Ca +  + influx to instigate TGF-β1. Modulation of AQP 1, 2, 3, 4, 9 and SLC protein and/or mRNAs expression levels during dehydration/rehydration was reported.

CONCLUSIONS

Long-term dehydration induces reversible or irreversible ultrastructural changes in kidney cortex with minor effects in medulla. Modulation of AQP channels, SLC and their mRNAs expression levels during dehydration/rehydration have a role in water conservation. Cortex and medulla respond differently to dehydration/rehydration.

Clinical implications of the Drug-Drug Interaction in Cancer Patients treated with innovative oncological treatments

In the last two-decades, innovative drugs have revolutionized cancer treatments, demonstrating a significant improvement in overall survival. These drugs may present several pharmacokinetics interactions with non-oncological drugs, and vice versa, and, non-oncological drugs can modify oncological treatment outcome both with pharmacokinetic interaction and with an "off-target impact" on the tumor microenvironment or on the peripheral immune response. It's supposed that the presence of a drug-drug interaction (DDI) is associated with an increased risk of reduced anti-tumor effects or severe toxicities. However, clinical evidence that correlate the DDI presence with outcome are few, and results are difficult to compare because of difference in data collection and heterogeneous population. This review reports all the clinical evidence about DDI to provide an easy-to-use guide for DDI management and dose adjustment in solid tumors treated with inhibitors of the cyclin-dependent kinases CDK4-6, Antibody-drug conjugates, Poly ADPribose polymerase inhibitors, androgen-receptor targeted agents, or immunecheckpoints inhibitors.

New Horizons of Synthetic Lethality in Cancer: Current Development and Future Perspectives

In recent years, synthetic lethality has been recognized as a solid paradigm for anticancer therapies. The discovery of a growing number of synthetic lethal targets has led to a significant expansion in the use of synthetic lethality, far beyond poly(ADP-ribose) polymerase inhibitors used to treat BRCA1/2-defective tumors. In particular, molecular targets within DNA damage response have provided a source of inhibitors that have rapidly reached clinical trials. This Perspective focuses on the most recent progress in synthetic lethal targets and their inhibitors, within and beyond the DNA damage response, describing their design and associated therapeutic strategies. We will conclude by discussing the current challenges and new opportunities for this promising field of research, to stimulate discussion in the medicinal chemistry community, allowing the investigation of synthetic lethality to reach its full potential.

Personalized Medicine in Pancreatic Cancer: The Promise of Biomarkers and Molecular Targeting with Dr. Michael J. Pishvaian

Pancreatic cancer, with its alarming rising incidence, is predicted to become the second deadliest type of solid tumor by 2040, highlighting the urgent need for improved diagnostic and treatment strategies. Despite medical advancements, the five-year survival rate for pancreatic cancer remains about 14%, dropping further when metastasized. This review explores the promise of biomarkers for early detection, personalized treatment, and disease monitoring. Molecular classification of pancreatic cancer into subtypes based on genetic mutations, gene expression, and protein markers guides treatment decisions, potentially improving outcomes. A plethora of clinical trials investigating different strategies are currently ongoing. Targeted therapies, among which those against CLAUDIN 18.2 and inhibitors of Claudin 18.1, have shown promise. Next-generation sequencing (NGS) has emerged as a powerful tool for the comprehensive genomic analysis of pancreatic tumors, revealing unique genetic alterations that drive cancer progression. This allows oncologists to tailor therapies to target specific molecular abnormalities. However, challenges remain, including limited awareness and uptake of biomarker-guided therapies. Continued research into the molecular mechanisms of pancreatic cancer is essential for developing more effective treatments and improving patient survival rates.

Promising Combinatorial Therapeutic Strategies against Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) presents a complex and diverse disease, exhibiting variations at individuals' cellular and histological levels. This complexity gives rise to different subtypes and genetic mutations, posing challenges for accurate diagnosis and effective treatment. Nevertheless, continuous progress in medical research and therapies is continually shaping the landscape of NSCLC diagnosis and management. The treatment of NSCLC has undergone significant advancements in recent years, especially with the emergence of targeted therapies that have shown remarkable efficacy in patients with actionable mutations. This has ushered in the era of personalized medicine in NSCLC treatment, with improvements in molecular and immunohistochemical techniques contributing to enhanced progression-free survival. This review focuses on the latest progress, challenges, and future directions in developing targeted therapies for NSCLC, including tyrosine kinase inhibitors (TKIs), DNA-damaging agents, immunotherapy regimens, natural drug therapy, and nanobodies. Furthermore, recent randomized studies have demonstrated enhanced overall survival in patients receiving different targeted and natural drug therapies.

Respiratory Virus-Induced PARP1 Alters DC Metabolism and Antiviral Immunity Inducing Pulmonary Immunopathology

Previous studies from our laboratory and others have established the dendritic cell (DC) as a key target of RSV that drives infection-induced pathology. Analysis of RSV-induced transcriptomic changes in RSV-infected DC revealed metabolic gene signatures suggestive of altered cellular metabolism. Reverse phase protein array (RPPA) data showed significantly increased PARP1 phosphorylation in RSV-infected DC. Real-time cell metabolic analysis demonstrated increased glycolysis in PARP1-/- DC after RSV infection, confirming a role for PARP1 in regulating DC metabolism. Our data show that enzymatic inhibition or genomic ablation of PARP1 resulted in increased ifnb1, il12, and il27 in RSV-infected DC which, together, promote a more appropriate anti-viral environment. PARP1-/- mice and PARP1-inhibitor-treated mice were protected against RSV-induced immunopathology including airway inflammation, Th2 cytokine production, and mucus hypersecretion. However, delayed treatment with PARP1 inhibitor in RSV-infected mice provided only partial protection, suggesting that PARP1 is most important during the earlier innate immune stage of RSV infection.

Homologous Recombination Repair Gene Mutations in Prostate Cancer: Prevalence and Clinical Value

Despite advances in our understanding of the molecular landscape of prostate cancer and the development of novel biomarker-driven therapies, the prognosis of patients with metastatic prostate cancer that is resistant to conventional hormonal therapy remains poor. Data suggest that a significant proportion of patients with metastatic castration-resistant prostate cancer (mCRPC) have mutations in homologous recombination repair (HRR) genes and may benefit from poly(ADP-ribose) polymerase (PARP) inhibitors. However, the adoption of HRR gene mutation testing in prostate cancer remains low, meaning there is a missed opportunity to identify patients who may benefit from targeted therapy with PARP inhibition, with or without novel hormonal agents. Here, we review the current knowledge regarding the clinical significance of HRR gene mutations in prostate cancer and discuss the efficacy of PARP inhibition in patients with mCRPC. This comprehensive overview aims to increase the clinical implementation of HRR gene mutation testing and inform future efforts in personalized treatment of prostate cancer.

Distinct Capabilities in NAD Metabolism Mediate Resistance to NAMPT Inhibition in Glioblastoma

Glioblastoma (GBM) cells require high levels of nicotinamide adenine dinucleotide (NAD) to fuel metabolic reactions, regulate their cell cycle and support DNA repair in response to chemotherapy and radiation. Inhibition of a key enzyme in NAD biosynthesis, NAMPT, has demonstrated significant anti-neoplastic activity. Here, we sought to characterise NAD biosynthetic pathways in GBM to determine resistance mechanisms to NAD inhibitors. GBM cells were treated with the NAMPT inhibitor FK866 with and without NAD precursors, and were analysed by qPCR, Western blot and proliferation assays (monolayer and spheroid). We also measured changes in the cell cycle, apoptosis, NAD/NADH levels and energy production. We performed orthoptic xenograft experiments in athymic nude mice to test the efficacy of FK866 in combination with temozolomide (TMZ). We show that the expression of key genes involved in NAD biosynthesis is highly variable across GBM tumours. FK866 inhibits proliferation, reduces NAD levels and limits oxidative metabolism, leading to G2/M cell cycle arrest; however, this can be reversed by supplementation with specific NAD precursors. Furthermore, FK866 potentiates the effects of radiation and TMZ in vitro and in vivo. NAMPT inhibitors should be considered for the treatment of GBM, with patients stratified based on their expression of key enzymes in other NAD biosynthetic pathways.

Influence of tumor microenvironment on the different breast cancer subtypes and applied therapies

Despite the significant improvements made in breast cancer therapy during the last decades, this disease still has increasing incidence and mortality rates. Different targets involved in general processes, like cell proliferation and survival, have become alternative therapeutic options for this disease, with some of them already used in clinic, like the CDK4/6 inhibitors for luminal A tumors treatment. Nevertheless, there is a demand for novel therapeutic strategies focused not only on tumor cells, but also on their microenvironment. Tumor microenvironment (TME) is a very complex and dynamic system that, more than surrounding and supporting tumor cells, actively participates in tumor development and progression. During the last decades, it has become clear that the cellular and acellular components of TME differ between the various breast cancer subtypes and shape the differences regarding their severity and prognosis. The pivotal role of the TME in controlling tumor growth and influencing responses to therapy represents a potential source for novel targets and therapeutic strategies. In this review, we present a description of the multiple therapeutic options used for different breast cancer subtypes, as well as the influence that the TME may exert on the development of the disease and on the response to the distinct therapies, which in some cases may explain their failure by the occurrence of relapses and resistance. Furthermore, the ongoing studies focused on the use of TME components for developing potential cancer treatments are described.

Gedunin modulates cellular growth and apoptosis in glioblastoma cell lines

BACKGROUND

Glioblastomas are characterized by aggressive behavior. Surgery, radiotherapy, and alkylating agents, including temozolomide are the most common treatment options for glioblastoma. Often, conventional therapies fail to treat these tumors since they develop drug resistance. There is a need for newer agents to combat this deadly tumor. Natural products such as gedunin have shown efficacy in several human diseases. A comprehensive study of gedunin, an heat shock protein (HSP)90 inhibitor, has not been thoroughly investigated in glioblastoma cell lines with different genetic modifications.

AIMS

A key objective of this study was to determine how gedunin affects the biological and signaling mechanisms in glioblastoma cells, and to determine how those mechanisms affect the proliferation and apoptosis of glioblastoma cells.

METHODS

The viability potentials of gedunin were tested using MTT, cell counts, and wound healing assays. Gedunin's effects on glioma cells were further validated using LDH and colony formation assays. In addition, we investigated the survival and apoptotic molecular signaling targets perturbed by gedunin using Western blot analysis and flow cytometry.

RESULTS

Our results show that there was a reduction in cell viability and inhibition of wound healing in the cells tested. Western blot analysis of the gene expression data revealed genes such as EGFR and mTOR/Akt/NF kappa B to be associated with gedunin sensitivity. Gedunin treatment induced apoptosis by cleaving poly ADP-ribose polymerase, activating caspases, and downregulating BCL-xL. Based on these results, gedunin suppressed cell growth and HSP client proteins, resulting in apoptosis in glioblastoma cell lines.

CONCLUSION

Our data provide in vitro support for the anticancer activity of gedunin in glioma cells by downregulating cancer survival proteins.

Dapagliflozin suppresses diabetes-induced oxidative DNA damage and hypermethylation in mouse somatic cells

Diabetes mellitus is a complex metabolic disorder resulting from the interplay of environmental, genetic, and epigenetic factors that increase the risk of cancer development. However, it is unclear whether the increased cancer risk is due to poor glycemic control or the use of some antidiabetic medications. Therefore, we investigated the genetic and epigenetic changes in somatic cells in a mouse model of diabetes and studied whether multiple exposures to the antidiabetic medication dapagliflozin influence these changes. We also elucidated the mechanism(s) of these ameliorations. The micronucleus test and modified comet assay were used to investigate bone marrow DNA damage and methylation changes. These assays revealed that dapagliflozin is non-genotoxic in the tested regimen, and oxidative DNA damage and hypermethylation were significantly higher in diabetic mice. Spectrophotometry also evaluated oxidative DNA damage and global DNA methylation, revealing similar significant alterations induced by diabetes. Conversely, the dapagliflozin-treated diabetic animals significantly reduced these changes. The expression of some genes involved in DNA repair and DNA methylation was disrupted considerably in the somatic cells of diabetic animals. In contrast, dapagliflozin treatment significantly restored these disruptions and enhanced DNA repair. The simultaneous effects of decreased oxidative DNA damage and hypermethylation levels suggest that dapagliflozin can be used as a safe antidiabetic drug to reduce DNA damage and hypermethylation in diabetes, demonstrating its usefulness in patients with diabetes to control hyperglycemia and decrease the development of its subsequent complications.

Development of novel pyrimidine nucleoside analogs as potential anticancer agents: Synthesis, characterization, and In-vitro evaluation against pancreatic cancer

The present study proposed modification of 5-FU by conjugation with an acyl chloride and a 5-membered heterocyclic ring to improve its in-vitro cytotoxicity and metabolic stability. XYZ-I-71 and XYZ-I-73 were synthesized by introducing a tetrahydrofuran ring on 5-fluorocytosine (a precursor of 5-FU) and conjugation with octanoyl chloride and lauroyl chloride, respectively. The structure of the synthesized compounds was validated using NMR and micro-elemental analysis. The antiproliferative activity of the analogs was determined against MiaPaCa-2, PANC-1, and BxPC-3 pancreatic cancer cells. The analog's stability in human liver microsomes was quantified by HPLC. We found that the XYZ-I-73 (IC50 3.6 ± 0.4 μM) analog was most effective against MiaPaCa-2 cells compared to XYZ-I-71(IC50 12.3 ± 1.7 μM), GemHCl (IC50 24.2 ± 1.3 μM), Irinotecan (IC50 10.1 ± 1.5 μM) and 5-FU (IC50 13.2 ± 1.1 μM). The antiproliferative effects of this analog in Miapaca-2 cells is evident based on it having a 7-fold,3-fold, and 4-fold increased cytotoxic effect over Gem-HCl, Irinotecan, and 5-FU, respectively. On the other hand, XYZ-I-71 exhibited a 2-fold increased cytotoxic effect over Gem-HCl but a comparable cytotoxic effect to 5-FU and Irinotecan in MiaPaCa-2 cells. A similar trend of higher XYZ-I-73 inhibition was observed in PANC-1 and BxPC-3 cultures. For 48-h MiaPaCa-2 cell migration studies, XYZ-I-73 (5 μM) significantly reduced migration (# of migrated cells, 168 ± 2.9), followed by XYZ-I-71(315±2.1), Gem-HCl (762±3.1) and 5-FU (710 ± 3.2). PARP absorbance studies demonstrated significant inhibition of PARP expression of XYZ-I-73 treated cells compared to 5-FU, GemHCl, and XYZ-I-71. Further, BAX and p53 expressions were significantly increased in cells treated with XYZ-I-73 compared to 5-FU, GemHCl, and XYZ-I-71. In-vitro, metabolic stability studies showed that 80 ± 5.9% of XYZ-I-71 and XYZ-I-73 remained intact after 2 h exposure in liver microsomal solution compared to 5-FU. The XYZ-I-73 analog demonstrated a remarkable cytotoxic effect and improved in-vitro metabolic stability over the selected standard drugs and may have potential anticancer activity against pancreatic cancer.

New synergistic combination therapy approaches with HDAC inhibitor quisinostat, cisplatin or PARP inhibitor talazoparib for urothelial carcinoma

Urothelial carcinoma (UC) urgently requires new therapeutic options. Histone deacetylases (HDAC) are frequently dysregulated in UC and constitute interesting targets for the development of alternative therapy options. Thus, we investigated the effect of the second generation HDAC inhibitor (HDACi) quisinostat in five UC cell lines (UCC) and two normal control cell lines in comparison to romidepsin, a well characterized HDACi which was previously shown to induce cell death and cell cycle arrest. In UCC, quisinostat led to cell cycle alterations, cell death induction and DNA damage, but was well tolerated by normal cells. Combinations of quisinostat with cisplatin or the PARP inhibitor talazoparib led to decrease in cell viability and significant synergistic effect in five UCCs and platinum-resistant sublines allowing dose reduction. Further analyses in UM-UC-3 and J82 at low dose ratio revealed that the mechanisms included cell cycle disturbance, apoptosis induction and DNA damage. These combinations appeared to be well tolerated in normal cells. In conclusion, our results suggest new promising combination regimes for treatment of UC, also in the cisplatin-resistant setting.

Therapeutic Targeting of DNA Repair Pathways in Pediatric Extracranial Solid Tumors: Current State and Implications for Immunotherapy

DNA damage is fundamental to tumorigenesis, and the inability to repair DNA damage is a hallmark of many human cancers. DNA is repaired via the DNA damage repair (DDR) apparatus, which includes five major pathways. DDR deficiencies in cancers give rise to potential therapeutic targets, as cancers harboring DDR deficiencies become increasingly dependent on alternative DDR pathways for survival. In this review, we summarize the DDR apparatus, and examine the current state of research efforts focused on identifying vulnerabilities in DDR pathways that can be therapeutically exploited in pediatric extracranial solid tumors. We assess the potential for synergistic combinations of different DDR inhibitors as well as combinations of DDR inhibitors with chemotherapy. Lastly, we discuss the immunomodulatory implications of targeting DDR pathways and the potential for using DDR inhibitors to enhance tumor immunogenicity, with the goal of improving the response to immune checkpoint blockade in pediatric solid tumors. We review the ongoing and future research into DDR in pediatric tumors and the subsequent pediatric clinical trials that will be critical to further elucidate the efficacy of the approaches targeting DDR.

Apoptosis Due to After-effects of Acute Ethanol Exposure in Brain Cortex: Intrinsic and Extrinsic Signaling Pathways

Alcohol hangover is the combination of negative mental and physical symptoms which can be experienced after a single episode of alcohol consumption, starting when blood alcohol concentration approaches zero. We previously demonstrated that hangover provokes mitochondrial dysfunction, oxidative stress, imbalance in antioxidant defenses, and impairment in cellular bioenergetics. Chronic and acute ethanol intake induces neuroapoptosis but there are no studies which evaluated apoptosis at alcohol hangover. The aim of the present work was to study alcohol residual effects on intrinsic and extrinsic apoptotic signaling pathways in mice brain cortex. Male Swiss mice received i.p. injection of ethanol (3.8 g/kg) or saline. Six hours after injection, at alcohol hangover onset, mitochondria and tissue lysates were obtained from brain cortex. Results indicated that during alcohol hangover a loss of granularity of mitochondria and a strong increment in mitochondrial permeability were observed, indicating the occurrence of swelling. Alcohol-treated mice showed a significant 35% increase in Bax/Bcl-2 ratio and a 5-fold increase in the ratio level of cytochrome c between mitochondria and cytosol. Caspase 3, 8 and 9 protein expressions were 32%, 33% and 20% respectively enhanced and the activity of caspase 3 and 6 was 30% and 20% increased also due to the hangover condition. Moreover, 38% and 32% increments were found in PARP1 and p53 protein expression respectively and on the contrary, SIRT-1 was almost 50% lower than controls due to the hangover condition. The present work demonstrates that alcohol after-effects could result in the activation of mitochondrial and non-mitochondrial apoptosis pathways.

DNA Adducts in Cancer Chemotherapy

DNA adducting drugs, including alkylating agents and platinum-containing drugs, are prominent in cancer chemotherapy. Their mechanisms of action involve direct interaction with DNA, resulting in the formation of DNA addition products known as DNA adducts. While these adducts are well-accepted to induce cancer cell death, understanding of their specific chemotypes and their role in drug therapy response remain limited. This perspective aims to address this gap by investigating the metabolic activation and chemical characterization of DNA adducts formed by the U.S. FDA-approved drugs. Moreover, clinical studies on DNA adducts as potential biomarkers for predicting patient responses to drug efficacy are examined. The overarching goal is to engage the interest of medicinal chemists and stimulate further research into the use of DNA adducts as biomarkers for guiding personalized cancer treatment.

The therapeutic perspective of NAD+ precursors in age-related diseases

Nicotinamide adenine dinucleotide (NAD+) is the fundamental molecule that performs numerous biological reactions and is crucial for maintaining cellular homeostasis. Studies have found that NAD+ decreases with age in certain tissues, and age-related NAD+ depletion affects physiological functions and contributes to various aging-related diseases. Supplementation of NAD+ precursor significantly elevates NAD+ levels in murine tissues, effectively mitigates metabolic syndrome, enhances cardiovascular health, protects against neurodegeneration, and boosts muscular strength. Despite the versatile therapeutic functions of NAD+ in animal studies, the efficacy of NAD+ precursors in clinical studies have been limited compared with that in the pre-clinical study. Clinical studies have demonstrated that NAD+ precursor treatment efficiently increases NAD+ levels in various tissues, though their clinical proficiency is insufficient to ameliorate the diseases. However, the latest studies regarding NAD+ precursors and their metabolism highlight the significant role of gut microbiota. The studies found that orally administered NAD+ intermediates interact with the gut microbiome. These findings provide compelling evidence for future trials to further explore the involvement of gut microbiota in NAD+ metabolism. Also, the reduced form of NAD+ precursor shows their potential to raise NAD+, though preclinical studies have yet to discover their efficacy. This review sheds light on NAD+ therapeutic efficiency in preclinical and clinical studies and the effect of the gut microbiota on NAD+ metabolism.

Anticancer Effects of α-Pinene in AGS Gastric Cancer Cells

Gastric cancer is the fifth most common cancer globally and the third leading cause of cancer-related mortality. Existing treatment strategies for gastric cancer often present numerous side effects. Consequently, recent studies have shifted toward devising new treatments grounded in safer natural substances. α-Pinene, a natural terpene found in the essential oils of various plants, such as Lavender angustifolia and Satureja myrtifolia, displays antioxidant, antibiotic, and anticancer properties. Yet, its impact on gastric cancer remains unexplored. This research assessed the effects of α-pinene in vitro using a human gastric adenocarcinoma cell-line (AGS) human gastric cancer cells and in vivo via a xenograft mouse model. The survival rate of AGS cells treated with α-pinene was notably lower than that of the control group, as revealed by the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide assay. This decline in cell viability was linked to apoptosis, as verified by 4',6-diamidino-2-phenylindole and annexin V/propidium iodide staining. The α-pinene-treated group exhibited elevated cleaved-poly (ADP-ribose) polymerase and B cell lymphoma 2 (Bcl-2)-associated X (Bax) levels and reduced Bcl-2 levels compared with the control levels. Moreover, α-pinene triggered the activation of extracellular signal-regulated kinase, c-Jun N-terminal kinase, and p38 within the mitogen-activated protein kinase (MAPK) pathway. In the xenograft mouse model, α-pinene induced apoptosis through the MAPK pathway, devoid of toxicity. These findings position α-pinene as a promising natural therapeutic for gastric cancer.

Drug-Loaded Nanogel for Efficient Orchestration of Cell Death Pathways by Intramitochondrial Disulfide Polymerization

Chemotherapy using a nanoscaled drug delivery system is an effective cancer therapy, but its high drug concentration often causes drug resistance in cancer cells and normal cell damage. Combination therapy involving two or more different cell signaling pathways can be a powerful tool to overcome the limitations of chemotherapy. Herein, this article presents nanogel (NG)-mediated co-delivery of a chemodrug camptothecin (CPT) and mitochondria-targeting monomer (MT monomer) for efficient activation of two modes of the programmed cell death pathway (apoptosis and necroptosis) and synergistic enhancement of cancer therapy. CPT and the monomer are incorporated together into the redox-degradable polymeric NGs for release in response to the intracellular glutathione. The MT monomer is shown to undergo reactive oxygen species (ROS)-triggered disulfide polymerization inside the cancerous mitochondria in cooperation with the chemotherapeutic CPT elevating the intracellular ROS level. The CPT/monomer interconnection in cell death mechanisms for mitochondrial dysfunction and enhanced cell death is evidenced by a series of cell analyses showing ROS generation, mitochondria damage, impacts on (non)cancerous or drug-resistant cells, and cell death modes. The presented work provides beneficial insights for utilizing combination therapy to facilitate a desired cell death mechanism and developing a novel nanosystem for more efficacious cancer treatment.

Discovery of novel PARP-1 inhibitors using tandem in silico studies: integrated docking, e-pharmacophore, deep learning based de novo and molecular dynamics simulation approach

Cancer accounts for the majority of deaths worldwide, and the increasing incidence of breast cancer is a matter of grave concern. Poly (ADP-ribose) polymerase-1 (PARP-1) has emerged as an attractive target for the treatment of breast cancer as it has an important role in DNA repair. The focus of the study was to identify novel PARP-1 inhibitors using a blend of tandem structure-based screening (Docking and e-pharmacophore-based screening) and artificial intelligence (deep learning)-based de novo approaches. The scrutiny of compounds having good binding characteristics for PARP-1 was carried out using a tandem mode of screening along with parameters such as binding energy and ADME analysis. The efforts afforded compound Vab1 (PubChem ID 129142036), which was chosen as a seed for obtaining novel compounds through a trained artificial intelligence (AI)-based model. Resultant compounds were assessed for PARP-1 inhibition; binding affinity prediction and interaction pattern analysis were carried out using the extra precision (XP) mode of docking. Two best hits, Vab1-b and Vab1-g, exhibiting good dock scores and suitable interactions, were subjected to 100 nanoseconds (ns) of molecular dynamics simulation in the active site of PARP-1 and compared with the reference Protein-Ligand Complex. The stable nature of PARP-1 upon binding to these compounds was revealed through MD simulation.Communicated by Ramaswamy H. Sarma.

Unravelling the molecular basis of PARP inhibitor resistance in prostate cancer with homologous recombination repair deficiency

Prostate cancer is a disease with heterogeneous characteristics, making its treatability and curability dependent on the cancer's stage. While prostate cancer is often indolent, some cases can be aggressive and evolve into metastatic castration-resistant prostate cancer (mCRPC), which is lethal. A significant subset of individuals with mCRPC exhibit germline and somatic variants in components of the DNA damage repair (DDR) pathway. Recently, PARP inhibitors (PARPi) have shown promise in treating mCRPC patients who carry deleterious alterations in BRCA2 and 13 other DDR genes that are important for the homologous recombination repair (HRR) pathway. These inhibitors function by trapping PARP, resulting in impaired PARP activity and increased DNA damage, ultimately leading to cell death through synthetic lethality. However, the response to these inhibitors only lasts for 3-4 months, after which the cancer becomes PARPi resistant. Cancer cells can develop resistance to PARPi through numerous mechanisms, such as secondary reversion mutations in DNA repair pathway genes, heightened drug efflux, loss of PARP expression, HRR reactivation, replication fork stability, and upregulation of Wnt/Catenin and ABCB1 pathways. Overcoming PARPi resistance is a critical and complex process, and there are two possible ways to sensitize the resistance. The first approach is to potentiate the PARPi agents through chemo/radiotherapy and combination therapy, while the second approach entails targeting different signaling pathways. This review article highlights the latest evidence on the resistance mechanism of PARPi in lethal prostate cancer and discusses additional therapeutic opportunities available for prostate cancer patients with DDR gene alterations who do not respond to PARPi.

Evaluation of the cytotoxic activity of sorafenib-loaded camel milk casein nanoparticles against hepatocarcinoma cells

Sorafenib, a multikinase inhibitor is used to treat hepatocellular and renal carcinoma. However, a low solubility impedes its bioavailability and thus, effectiveness. This study aims to enhance its effectiveness by using novel camel milk casein nanoparticles as a delivery system. This study evaluates the cytotoxicity of sorafenib encapsulated in camel milk casein nanoparticles against human hepatocarcinoma cells (HepG2 cells) in vitro. Optimal drug loaded nanoparticles were stable for 1 month, had encapsulation efficiency of 96%, exhibited a particle size of 230 nm, zeta potential of -14.4 and poly disparity index of 0.261. Treatment with it led to cell morphology and DNA fragmentation as a characteristic of apoptosis. Flow cytometry showed G1 phase arrest of cell cycle and 26% increased apoptotic cells population upon treatment as compared to control. Sorafenib-loaded casein nanoparticles showed 6-fold increased ROS production in HepG2 cells as compared to 4-fold increase shown by the free drug. Gene and protein expression studies done by qPCR and western blotting depicted upregulation of tumor suppressor gene p53, pro-apoptotic Bax, and caspase-3 along with downregulated anti-apoptotic Bcl-2 gene and protein expression which further emphasized death by apoptosis. It is concluded regarding the feasibility of these casein nanoparticles as a delivery system with enhanced therapeutic outcomes against hepatocellular carcinoma cells.

NAD in pathological cardiac remodeling: Metabolic regulation and beyond

Nicotinamide adenine dinucleotide (NAD) coenzymes are carriers of high energy electrons in metabolism and also play critical roles in numerous signaling pathways. NAD metabolism is decreased in various cardiovascular diseases. Importantly, stimulation of NAD biosynthesis protects against heart disease under different pathological conditions. In this review, we describe pathways for both generation and catabolism of NAD coenzymes and the respective changes of these pathways in the heart under cardiac diseases, including pressure overload, myocardial infarction, cardiometabolic disease, cancer treatment cardiotoxicity, and heart failure. We next provide an update on the strategies and treatments to increase NAD levels, such as supplementation of NAD precursors, in the heart that prevent or reverse cardiomyopathy. We also introduce the approaches to manipulate NAD consumption enzymes to ameliorate cardiac disease. Finally, we discuss the mechanisms associated with improvements in cardiac function by NAD coenzymes, differentiating between mitochondria-dependent effects and those independent of mitochondrial metabolism.

Promises of Protein Kinase Inhibitors in Recalcitrant Small-Cell Lung Cancer: Recent Scenario and Future Possibilities

SCLC is refractory to conventional therapies; targeted therapies and immunological checkpoint inhibitor (ICI) molecules have prolonged survival only marginally. In addition, ICIs help only a subgroup of SCLC patients. Different types of kinases play pivotal roles in therapeutics-driven cellular functions. Therefore, there is a significant need to understand the roles of kinases in regulating therapeutic responses, acknowledge the existing knowledge gaps, and discuss future directions for improved therapeutics for recalcitrant SCLC. Here, we extensively review the effect of dysregulated kinases in SCLC. We further discuss the pharmacological inhibitors of kinases used in targeted therapies for recalcitrant SCLC. We also describe the role of kinases in the ICI-mediated activation of antitumor immune responses. Finally, we summarize the clinical trials evaluating the potential of kinase inhibitors and ICIs. This review overviews dysregulated kinases in SCLC and summarizes their potential as targeted therapeutic agents. We also discuss their clinical efficacy in enhancing anticancer responses mediated by ICIs.

Use of antioxidant nanoliposomes for co-delivery of PTEN plasmids and plumbagin to induce apoptosis in hepatic cancer cells

Hepatocellular carcinoma remains a challenging contributor to the global cancer and related mortality, and claims approximately 800,000 deaths each year. Dysregulation or loss of function mutations involving the tumor suppressor gene, phosphatase and tensin homolog deleted on chromosome ten (PTEN), has been well-characterized in various cancers to elicit anomalous cell proliferation and oncogenic transformation. However, the delivery and bioavailability of genes/drugs of interest to carcinomas remains a serious bottleneck behind the success of any anti-cancer formulation. In this study, we have engineered nanoliposomes containing PTEN plasmids, plumbagin, and antioxidant cerium oxide nanoparticles (Lipo-PTEN-Plum) to restore the PTEN expression and inhibit the AKT/PI3K pathway. The Lipo-PTEN-Plum was quasi-spherical in shape with ∼110 nm diameter and ∼64% plumbagin loading efficiency. The Lipo-PTEN-Plum was successfully internalized HepG2 cells, restore PTEN expression and inhibit PI3K/AKT pathway to induce death in cells grown in monolayer and in form of spheroids. Mechanistically, the formulation showed G2/M cell cycle arrest, DNA damage and apoptosis in hepatic cancer cells. Other cellular events such as Caspase-7 overexpression and PI3K (phosphoinositide 3-kinase), AKT (a serine/threonine protein kinase), PARP [Poly (ADP-ribose) polymerases], and mTOR (Mammalian target of rapamycin) inhibition led to the apoptosis in hepatic cancer cells. The mRNA expression profile of PTEN, PI3K, AKT3, Caspase-7, PARP and mTOR proteins, primarily controlling the cancer cell proliferation and apoptosis, suggest that exogenous supply of PTEN could regulate the expression of oncogenic proteins and thus cancer progression.

The role of cell-matrix adhesion and cell migration in breast tumor growth and progression

During breast cancer progression, there is typically increased collagen deposition resulting in elevated extracellular matrix rigidity. This results in changes to cell-matrix adhesion and cell migration, impacting processes such as the epithelial-mesenchymal transition (EMT) and metastasis. We aim to investigate the roles of cell-matrix adhesion and cell migration on breast tumor growth and progression by studying the impacts of different types of extracellular matrices and their rigidities. We embedded MCF7 spheroids within three-dimensional (3D) collagen matrices and agarose matrices. MCF7 cells adhere to collagen but not agarose. Contrasting the results between these two matrices allows us to infer the role of cell-matrix adhesion. We found that MCF7 spheroids exhibited the fastest growth rate when embedded in a collagen matrix with a rigidity of 5.1 kPa (0.5 mg/mL collagen), whereas, for the agarose matrix, the rigidity for the fastest growth rate is 15 kPa (1.0% agarose) instead. This discrepancy is attributable to the presence of cell adhesion molecules in the collagen matrix, which initiates collagen matrix remodeling and facilitates cell migration from the tumor through the EMT. As breast tumors do not adhere to agarose matrices, it is suitable to simulate the cell-cell interactions during the early stage of breast tumor growth. We conducted further analysis to characterize the stresses exerted by the expanding spheroid on the agarose matrix. We identified two distinct MCF7 cell populations, namely, those that are non-dividing and those that are dividing, which exerted low and high expansion stresses on the agarose matrix, respectively. We confirmed this using Western blot which showed the upregulation of proliferating cell nuclear antigen, a proliferation marker, in spheroids grown in the 1.0% agarose (≈13 kPa). By treating the embedded MCF7 spheroids with an inhibitor or activator of myosin contractility, we showed that the optimum spheroids' growth can be increased or decreased, respectively. This finding suggests that tumor growth in the early stage, where cell-cell interaction is more prominent, is determined by actomyosin tension, which alters cell rounding pressure during cell division. However, when breast tumors begin generating collagen into the surrounding matrix, collagen remodeling triggers EMT to promote cell migration and invasion, ultimately leading to metastasis.

PARP1 as an Epigenetic Modulator: Implications for the Regulation of Host-Viral Dynamics

The principal understanding of the Poly(ADP-ribose) polymerase (PARP) regulation of genomes has been focused on its role in DNA repair; however, in the past few years, an additional role for PARPs and PARylation has emerged in regulating viral-host interactions. In particular, in the context of DNA virus infection, PARP1-mediated mechanisms of gene regulations, such as the involvement with cellular protein complexes responsible for the folding of the genome into the nucleus, the formation of chromatin loops connecting distant regulatory genomic regions, and other methods of transcriptional regulation, provide additional ways through which PARPs can modulate the function of both the host and the viral genomes during viral infection. In addition, potential viral amplification of the activity of PARPs on the host genome can contribute to the pathogenic effect of viral infection, such as viral-driven oncogenesis, opening the possibility that PARP inhibition may represent a potential therapeutic approach to target viral infection. This review will focus on the role of PARPs, particularly PARP1, in regulating the infection of DNA viruses.

Enhanced potency of a chloro-substituted polyaromatic platinum(II) complex and its platinum(IV) prodrug against lung cancer

The present study investigates the anti-neoplastic activity of a platinum (II) complex, Pt(II)5ClSS, and its platinum (IV) di-hydroxido analogue, Pt(IV)5ClSS, against mesenchymal cells (MCs), lung (A549), melanoma (A375) and breast (MDA-MB-231) cancer cells. Both complexes exhibited up to 14-fold improved cytotoxicity compared to cisplatin. NMR was used to determine that ∼25 % of Pt(IV)5ClSS was reduced to Pt(II)5ClSS in the presence of GSH (Glutathione) after 72 h. The complex 1H NMR spectra acquired for Pt(II)5ClSS with GSH shows evidence of degradation and environmental effects (∼30 %). The prominence of the 195Pt peak at ∼ -2800 ppm suggests that a significant amount of Pt(II)5ClSS remained in the mixture. Pt(II)5ClSS and Pt(IV)5ClSS have shown exceptional selectivity to cancer cells in comparison to MCs (IC50 > 150 μM). Western blot analysis of Pt(II)5ClSS and Pt(IV)5ClSS on A549 cells revealed significant upregulation of cleaved PARP-1, BAX/Bcl2 ratio, cleaved caspase 3 and cytochrome thus suggesting apoptosis was induced through the intrinsic pathway. Flow cytometry also revealed significant cell death by apoptosis. Treatment with Pt(II)5ClSS and Pt(IV)5ClSS also showed significant amounts of free radical production while the COMET assay showed that both complexes cause minimal DNA damage. Cellular uptake results via ICP-MS suggest a time-dependent active mode of transport for both complexes with Pt(II)5ClSS being transported at a higher rate compared to Pt(IV)5ClSS. A Dose Escalation Study carried out on BALB/c mice showed that Pt(II)5ClSS and Pt(IV)5ClSS were approximately 8- folds and 12.5-folds, respectively, more tolerated than cisplatin. The present study provides evidence that both complexes may have the characteristics of an efficient and potentially safe anti-tumor drug that could support NSCLC treatment.

Drug-Resistant Epithelial Ovarian Cancer: Current and Future Perspectives

Epithelial ovarian cancer (EOC) is a complex disease with diverse histological subtypes, which, based on the aggressiveness and course of disease progression, have recently been broadly grouped into type I (low-grade serous, endometrioid, clear cell, and mucinous) and type II (high-grade serous, high-grade endometrioid, and undifferentiated carcinomas) categories. Despite substantial differences in pathogenesis, genetics, prognosis, and treatment response, clinical diagnosis and management of EOC remain similar across the subtypes. Debulking surgery combined with platinum-taxol-based chemotherapy serves as the initial treatment for High Grade Serous Ovarian Carcinoma (HGSOC), the most prevalent one, and for other subtypes, but most patients exhibit intrinsic or acquired resistance and recur in short duration. Targeted therapies, such as anti-angiogenics (e.g., bevacizumab) and PARP inhibitors (for BRCA-mutated cancers), offer some success, but therapy resistance, through various mechanisms, poses a significant challenge. This comprehensive chapter delves into emerging strategies to address these challenges, highlighting factors like aberrant miRNAs, metabolism, apoptosis evasion, cancer stem cells, and autophagy, which play pivotal roles in mediating resistance and disease relapse in EOC. Beyond standard treatments, the focus of this study extends to alternate targeted agents, including immunotherapies like checkpoint inhibitors, CAR T cells, and vaccines, as well as inhibitors targeting key oncogenic pathways in EOC. Additionally, this chapter covers disease classification, diagnosis, resistance pathways, standard treatments, and clinical data on various emerging approaches, and advocates for a nuanced and personalized approach tailored to individual subtypes and resistance mechanisms, aiming to enhance therapeutic outcomes across the spectrum of EOC subtypes.

Novel Strategies Using Sagacious Targeting for Site-Specific Drug Delivery in Breast Cancer Treatment: Clinical Potential and Applications

For more than a decade, researchers have been working to achieve new strategies and smart targeting drug delivery techniques and technologies to treat breast cancer (BC). Nanotechnology presents a hopeful strategy for targeted drug delivery into the building of new therapeutics using the properties of nanomaterials. Nanoparticles are of high regard in the field of diagnosis and the treatment of cancer. The use of these nanoparticles as an encouraging approach in the treatment of various cancers has drawn the interest of researchers in recent years. In order to achieve the maximum therapeutic effectiveness in the treatment of BC, combination therapy has also been adopted, leading to minimal side effects and thus an enhancement in the quality of life for patients. This review article compares, discusses and criticizes the approaches to treat BC using novel design strategies and smart targeting of site-specific drug delivery systems.

Cobalt-induced apoptosis of cochlear organotypic cultures and HEI-OC1 cells is mediated by Dicer

Cobalt is widely used in the medical industry, mainly including cobalt alloy joint implants and cobalt-chromium porcelain crowns. However, unexplained ototoxicity and neurotoxicity often occur in the clinical use of cobalt agents at present, which limits the development of the cobalt industry. In this study, based on the clinical problem of cobalt ototoxicity, we first conducted an extensive search and collation of related theories, and on this basis, prepared an HEI-OC1 cell model and basilar membrane organotypic cultures after cobalt treatment. We used immunofluorescence staining, western blot, CCK8, and si-RNA to investigate the mechanism of cobalt ototoxicity, to discover its potential therapeutic targets. After comparing the reactive oxygen species, mitochondrial transmembrane potential, apoptosis-related protein expression, and cell viability of different treatment groups, the following conclusions were drawn: cobalt causes oxidative stress in the inner ear, which leads to apoptosis of inner ear cells; inhibition of oxidative stress and apoptosis can alleviate the damage of cobalt on inner ear cells; and the Dicer protein plays a role in the mechanism of inner ear damage and is a potential target for the treatment of cobalt-induced inner ear damage. Taken together, these results suggest that cobalt-induced ototoxicity triggered by oxidative stress activates a cascade of apoptotic events where cCaspase-3 decreases Dicer levels and amplifies this apoptotic pathway. It may be possible to prevent and treat cobalt ototoxicity by targeting this mechanism.

Radiosensitization of Osteosarcoma Cells Using the PARP Inhibitor Olaparib Combined with X-rays or Carbon Ions

Objective: Osteosarcomas are derived from bone-forming mesenchymal cells that are insensitive to radiation. This study aimed to investigate the radiosensitization of osteosarcoma cells (U2OS and K7M2) using the PARP inhibitor olaparib combined with X-rays or carbon ions (C-ions). Methods: The effect of olaparib on the proliferation of osteosarcoma cells after irradiation was assessed using CCK-8 and clone formation assays. Cells were treated with olaparib and/or radiation and the effects of olaparib on the cell cycle and apoptosis were analysed by flow cytometry after 48h. Immunofluorescence was used to stain the nuclei, γ-H2AX, 53BP1, and Rad51 proteins, and the number of γ-H2AX, 53BP1, and Rad51 foci was observed under a fluorescence microscope. The effect of olaparib combined with radiation on double-stranded DNA breaks in osteosarcoma cells was evaluated. Results: At the same radiation dose, olaparib reduced the proliferation and colony formation ability of irradiated osteosarcoma cells (P < 0.05). Olaparib monotherapy induced minimal apoptotic effects and G2/M phase arrest in osteosarcoma cells and irradiation alone induced moderate apoptosis and G2/M phase arrest. However, radiation combined with olaparib significantly increased the percentage of apoptotic cells and G2/M phase arrest in osteosarcoma cells (P < 0.05). Immunofluorescence experiments showed that compared to the radiation group, the formation of γ-H2AX and 53BP1 foci was significantly increased in the combined group (P < 0.05). The expression levels of Rad51 foci in the irradiated group were higher than those in the control group (P < 0.05). However, the number of Rad51 foci in the combined group was significantly decreased (P < 0.05). Conclusion: The PARP inhibitor olaparib combined with irradiation (X-rays or C-ions) enhanced the radiosensitivity of osteosarcoma cell lines (U2OS and K7M2). Our findings provide a potential theoretical basis for the clinical application of olaparib in overcoming radiation resistance in osteosarcoma.