Cisplatin-resistant Cell Lines Research Articles

In vitro anticancer activity of a head-to-toe constructed heterobimetallic [CoFeL]2+ metallocylinder

ABSTRACT [M2L3]-type metallo-supramolecular architectures (MSAs) are widely explored for their biological activity, whereas data on non-symmetric, heterobimetallic [MM’L3] structures is comparatively rare. [M2L3] compounds are known to form helicates and/or mesocates. Here, we report the self-assembly of a discrete non-symmetrical, heterobimetallic MSA by combination of an amine-functionalised cobalt(III)-tris((picolinamido)ethyl)amine (PICTREN) base unit with FeCl2 and 2,2’-bipyridine-5-carboxaldehyde. NMR spectroscopy in tandem with computational studies revealed the formation of a mesocate rather than a helicate. The ability of the heteromesocate to bind to DNA was examined by gel electrophoresis with pUC19 plasmid DNA, which showed DNA binding although longer incubation periods were required than found for a known DNA-interacting helicate. The mesocate displayed promising antiproliferative activity in cancer cells, including a cisplatin-resistant cell line, with IC50 values in the 17–26 μM range. Lower biological activity of the mesocate compared to a metallocylinder reference and cisplatin may be explained by differences in the DNA interactions. This work further supports efforts to establish methods with which to construct heterobimetallic complexes, establishing the utility of the self-assembly method in [M2L3]-type assemblies using the cobalt(III)-PICTREN platform as a robust building block towards more complex assemblies of the [MM’L]-type.

Silencing Nrf2 in cisplatin resistant non-small cell lung cancer cells augments sensitivity towards EGFR inhibitor

Recently, non-small cell lung cancer (NSCLC) has been the prime concern of cancer clinicians due to its high mortality rate worldwide. Cisplatin, a platinum derivative, has been used as a therapeutic option for treating metastatic NSCLC for several years. However, acquired, or intrinsic drug resistance to Cisplatin is the major obstacle to the successful treatment outcome of patients. Dysregulation of Nrf2 (nuclear factor erythroid 2-related factor 2) and EGFR (epidermal growth factor receptor) signaling have been associated with cellular proliferation, cancer initiation, progression and confer drug resistance to several therapeutic agents including Cisplatin in various cancers. To dissect the molecular mechanism of EGFR activation in resistant cells, we developed Cisplatin-resistant (CisR) human NSCLC cell lines (A549 and NCIH460) with increasing doses of Cisplatin treatment over a 3-month period. CisR cells demonstrated increased proliferative capacity, clonogenic survivability and drug efflux activity compared to the untreated parental (PT) cells. These resistant cells also showed higher levels of Nrf2 and EGFR expression. Here, we found that Nrf2 upregulates both basal and inducible expression of EGFR in these CisR cells at the transcriptional level. Moreover, genetic inhibition of Nrf2 with siRNA in CisR cells showed increased sensitivity towards the EGFR tyrosine kinase inhibitor (TKIs), AG1478. Our study, therefore suggests the use of Nrf2 inhibitors in combinatorial therapy with EGFR TKIs for the treatment of resistant NSCLC.

A novel combinatory treatment against a CDDP-resistant non-small cell lung cancer based on a Ruthenium(II)-cyclopentadienyl compound

The therapeutic approach to many solid tumors, including non-small cell lung cancer (NSCLC), is mainly based on the use of platinum-containing anticancer agents and is often characterized by acquired or intrinsic resistance to the drug. Therefore, the search for safer and more effective drugs is still an open challenge.Two organometallic ruthenium(II)-cyclopentadienyl compounds [Ru(η5-C5H4CHO)(Me2bipy)(PPh3)]+ (RT150) and [Ru(η5-C5H4CH2OH)(Me2bipy)(PPh3)][CF3SO3] (RT151) were tested against a panel of cisplatin-resistant NSCLC cell lines and xenografts. They were more effective than cisplatin in inducing oxidative stress and DNA damage, affecting the cell cycle and causing apoptosis. Importantly, they were found to be inhibitors of drug efflux transporters. Due to this property, the compounds significantly increased the retention and cytotoxicity of cisplatin within NSCLC cells. Notably, they did not display high toxicity in vitro against non-transformed cells (red blood cells, fibroblasts, bronchial epithelial cells, cardiomyocytes, and endothelial cells). Both compounds induced vasorelaxation and reduced endothelial cell migration, suggesting potential anti-angiogenic properties. RT151 confirmed its efficacy against NSCLC xenografts resistant to cisplatin. Either alone or combined with low doses of cisplatin, RT151 showed a good biodistribution profile in the liver, kidney, spleen, lung, and tumor. Hematochemical analysis and post-mortem organ pathology confirmed the safety of the compound in vivo, also when combined with cisplatin.To sum up, we have confirmed the effectiveness of a novel class of drugs against cisplatin-resistant NSCLC. Additionally, the compounds have a good biocompatibility and safety profile.

Cabazitaxel as a promising therapy for cisplatin-resistant bladder cancer: a preliminary study.

Bladder cancer is a common malignancy worldwide, posing a substantial healthcare challenge. Current standard treatment regimens are primarily based on cisplatin, but their success is often limited by cisplatin resistance and associated toxicities. Therefore, there is an urgent need to develop effective and less toxic therapies as alternatives to cisplatin. We screened the activity of FDA-approved anti-cancer drugson a panel of cisplatin-resistant bladder cancer cell lines. Based on initial responses, cabazitaxel was selected for further evaluation of its inhibitory effects on the phenotypic properties of these cells. Cabazitaxel, primarily used for metastatic castration-resistant prostate cancer, demonstrated remarkable efficacy in inhibiting colony formation, proliferation, and migration of cisplatin-resistant bladder cancer cells. This study highlights the potential of drug repurposing as a cost-effective and efficient strategy to overcome drug resistance in bladder cancer.

Circular RNA circ_ARHGEF28 inhibits MST1/2 dimerization to suppress Hippo pathway to induce cisplatin resistance in ovarian cancer

BackgroundCisplatin is integral to ovarian cancer treatment, yet resistance to this drug often results in adverse patient outcomes. The association of circular RNA (circRNA) with cisplatin resistance in ovarian cancer has been observed, but the mechanisms governing this relationship require further elucidation.MethodsHigh-throughput sequencing was utilized to profile circRNA expression in cisplatin-resistant ovarian cancer cells. Gain-and-loss-of-function experiments assessed the impact on cisplatin sensitivity, both in vitro and in vivo. Fluorescence in situ hybridization was conducted to determine the cellular distribution of circRNAs, and RNA pulldown and immunoprecipitation experiments were performed to identify associated binding proteins.ResultsThe study revealed that circ_ARHGEF28 is overexpressed in certain cisplatin-resistant ovarian cancer tissues and cell lines, and is associated with reduced progression-free survival in patients. It was observed that circ_ARHGEF28 contributes to cisplatin resistance in ovarian cancer models, both in vitro and in vivo. Importantly, circ_ARHGEF28 was found to interact directly with MST1/2, inhibiting the SARAH coiled-coil binding domains and consequently deactivating the Hippo pathway.ConclusionThis investigation identifies circ_ARHGEF28 as a novel circRNA that contributes to cisplatin resistance in ovarian cancer by suppressing the Hippo pathway. Therapeutic strategies targeting circ_ARHGEF28 may offer a potential avenue to mitigate cisplatin resistance in ovarian cancer treatment.

Comprehensive analysis of hub genes associated with cisplatin-resistance in ovarian cancer and screening of therapeutic drugs through bioinformatics and experimental validation

BackgroundTo identify key genes associated with cisplatin resistance in ovarian cancer, a comprehensive analysis was conducted on three datasets from the GEO database and through experimental validation.MethodsGene expression profiles were retrieved from the GEO database. DEGs were identified by comparing gene expression profiles between cisplatin-sensitive and resistant ovarian cancer cell lines. The identified genes were further subjected to GO, KEGG, and PPI network analysis. Potential inhibitors of key genes were identified through methods such as LibDock nuclear molecular docking. In vitro assays and RT-qPCR were performed to assess the expression levels of key genes in ovarian cancer cell lines. The sensitivity of cells to chemotherapy and proliferation of key gene knockout cells were evaluated through CCK8 and Clonogenic assays.ResultsResults showed that 12 genes influenced the chemosensitivity of the ovarian cancer cell line SKOV3, and 9 genes were associated with the prognosis and survival outcomes of ovarian cancer patients. RT-qPCR results revealed NDRG1, CYBRD1, MT2A, CNIH3, DPYSL3, and CARMIL1 were upregulated, whereas ERBB4, ANK3, B2M, LRRTM4, EYA4, and SLIT2 were downregulated in cisplatin-resistant cell lines. NDRG1, CYBRD1, and DPYSL3 knock-down significantly inhibited the proliferation of cisplatin-resistant cell line SKOV3. Finally, photofrin, a small-molecule compound targeting CYBRD1, was identified.ConclusionThis study reveals changes in the expression level of some genes associated with cisplatin-resistant ovarian cancer. In addition, a new small molecule compound was identified for the treatment of cisplatin-resistant ovarian cancer.

The Induction of G2/M Phase Cell Cycle Arrest and Apoptosis by the Chalcone Derivative 1C in Sensitive and Resistant Ovarian Cancer Cells Is Associated with ROS Generation.

Ovarian cancer ranks among the most severe forms of cancer affecting the female reproductive organs, posing a significant clinical challenge primarily due to the development of resistance to conventional therapies. This study investigated the effects of the chalcone derivative 1C on sensitive (A2780) and cisplatin-resistant (A2780cis) ovarian cancer cell lines. Our findings revealed that 1C suppressed cell viability, induced cell cycle arrest at the G2/M phase, and triggered apoptosis in both cell lines. These effects are closely associated with generating reactive oxygen species (ROS). Mechanistically, 1C induced DNA damage, modulated the activity of p21, PCNA, and phosphorylation of Rb and Bad proteins, as well as cleaved PARP. Moreover, it modulated Akt, Erk1/2, and NF-κB signaling pathways. Interestingly, we observed differential effects of 1C on Nrf2 levels between sensitive and resistant cells. While 1C increased Nrf2 levels in sensitive cells after 12 h and decreased them after 48 h, the opposite effect was observed in resistant cells. Notably, most of these effects were suppressed by the potent antioxidant N-acetylcysteine (NAC), underscoring the crucial role of ROS in 1C-induced antiproliferative activity. Moreover, we suggest that modulation of Nrf2 levels can, at least partially, contribute to the antiproliferative effect of chalcone 1C.

Targeting metabolic reprogramming to overcome drug resistance in advanced bladder cancer: insights from gemcitabine- and cisplatin-resistant models.

Gemcitabine plus cisplatin (GC) combination chemotherapy is the primary treatment for advanced bladder cancer (BC) with unresectable or metastatic disease. However, most cases develop resistance to this therapy. We investigated whether drug resistance could be targeted through metabolic reprogramming therapies. Metabolomics analyses in our lab's gemcitabine- and cisplatin-resistant cell lines revealed increased phosphoglycerate dehydrogenase (PHGDH) expression in gemcitabine-resistant cells compared with parental cells. Isocitrate dehydrogenase 2 (IDH2) gain of function stabilized hypoxia-inducible factor1α (HIF1α) expression, stimulating aerobic glycolysis. In gemcitabine-resistant cells, elevated fumaric acid suppressed prolyl hydroxylase domain-containing protein 2/Egl nine homolog 1 (PHD2) and stabilized HIF1α expression. PHGDH downregulation or inhibition in gemcitabine-resistant BC cells inhibited their proliferation, migration, and invasion. Cisplatin-resistant cells showed elevated fatty acid metabolism, upregulating fatty acid synthase (FASN) downstream of tyrosine kinase. Using the fibroblast growth factor receptor (FGFR) tyrosine kinase inhibitor erdafitinib, we inhibited malonyl-CoA production, which is crucial for fatty acid synthesis, and thereby suppressed upregulated HIF1α expression. Combination treatment with NCT503 and erdafitinib synergistically suppressed tumor cell proliferation and induced apoptosis in vitro and in vivo. Understanding these mechanisms could enable innovative BC therapeutic strategies to be developed.

P27Kip1 and cytoplasmic pSer10p27 are promising biomarkers for predicting prognosis and chemotherapy response in ovarian cancer.

The biological function of p27Kip1 largely depends on its subcellular localization and phosphorylation status. Different subcellular localizations and phosphorylation statuses of p27Kip1 may represent distinct clinical values, which are unclear in ovarian cancer. This study aimed to elucidate different subcellular localizations of p27Kip1 and pSer10p27 in predicting prognosis and chemotherapy response in ovarian cancer. Meta-analyses were executed to evaluate the association of p27Kip1 and phosphorylated p27Kip1 with the prognosis of ovarian cancer patients. The expression levels and patterns of p27Kip1 and pSer10p27 were evaluated by immunohistochemistry. The correlations between different p27Kip1 states, clinicopathological features, and prognosis were analyzed. p27Kip1 and pSer10p27 expression levels in cisplatin-sensitive and cisplatin-resistant ovarian cancer cell lines were detected using WB. KEGG analysis and WB were performed to evaluate the pathways in which p27Kip1 was involved. Meta-analyses showed that p27Kip1 was associated with significantly better overall survival (OS) in ovarian cancer (HR=2.14; 95% CI [1.71-2.68]) and pSer10p27 was associated with significantly poor OS in mixed solid tumors (HR=2.56; 95% CI [1.76-3.73]). In our cohort of ovarian cancer patients, low total p27Kip1 remained independent risk factors of OS (HR=2.097; 95% CI [1.121-3.922], P=0.021) and PFS (HR=2.483; 95% CI [1.364-4.518], P=0.003), while low cytoplasmic pSer10p27 had independent protective effects in terms of OS (HR=0.472; 95% CI [0.248-0.898], P=0.022) and PFS (HR=0.488; 95% CI [0.261-0.910], P=0.024). Patients with low total p27Kip1/pSer10p27 and low nuclear p27Kip1 had worse chemotherapy responses, while patients with low cytoplasmic pSer10p27 expression had better chemotherapy responses. The protein levels of p27Kip1 and pSer10p27 were significantly reduced in the cisplatin-resistant cell lines SKOV3-cDDP and A2780-cDDP, and the level of p27Kip1/pSer10p27 was subjective to Akt activation. The present study demonstrates that p27Kip1 and cytoplasmic pSer10p27 are promising biomarkers for predicting prognosis and chemotherapy response in ovarian cancer.

CDKN2A inhibited ferroptosis through activating JAK2/STAT3 pathway to modulate cisplatin resistance in cervical squamous cell carcinoma.

Cervical squamous cell carcinoma (CESC) is a significant threat to women's health. Resistance to cisplatin (DDP), a common treatment, hinders the therapeutic efficacy. Understanding the molecular basis of DDP resistance in CESC is imperative. Cyclin-dependent kinase inhibitor 2A (CDKN2A) expression was evaluated through quantitative real-time-PCR and western blot in clinical samples from 30 CESC patients and human cervical epithelial cells and CESC cell lines (SiHa, C33A, and Caski). It was also evaluated through bioinformatics analysis in Timer, Ualcan, and GEPIA database. Cell viability was detected by CCK-8. Apoptosis was detected by Calcein AM/PI assay. Lipid reactive oxygen species (ROS), malondialdehyde, glutathione, Fe 2+ , and iron level were detected by kits. Protein level of JAK2, STAT3, p-JAK2, p-STAT3, ACSL4, GPX4, SLC7A11, and FTL were detected by western blot. In CESC, elevated CDKN2A expression was observed. Cisplatin exhibited a dual effect, inhibiting cell proliferation and inducing ferroptosis in CESC. CDKN2A knockdown in a cisplatin-resistant cell line suppressed proliferation and induced ferroptosis. Moreover, CDKN2A was identified as an inhibitor of erastin-induced ferroptosis. Additionally, targeting the JAK2/STAT3 pathway enhanced ferroptosis in cisplatin-resistant cells. CDKN2A could inhibit ferroptosis in CESC through activating JAK2/STAT3 pathway to modulate cisplatin resistance.

Capsaicin reverses cisplatin resistance in tongue squamous cell carcinoma by inhibiting the Warburg effect and facilitating mitochondrial-dependent apoptosis via the AMPK/AKT/mTOR axis.

Cisplatin is commonly used for the chemotherapy of tongue squamous cell carcinoma (TSCC); however, adverse side effects and drug resistance impact its therapeutic efficacy. Capsaicin is an active ingredient in chili peppers that exerts antitumor effects, whether it exerts antitumor effects on cisplatin-resistant cells remains unknown. Therefore, in this study, we investigated the effect of capsaicin on cisplatin resistance in TSCC cells and explored the underlying mechanisms. A cisplatin-resistant TSCC cell line was established by treated with increasing cisplatin concentrations. Combined treatment with cisplatin and capsaicin decreased the glucose consumption and lactate dehydrogenase activity and increased the adenosine triphosphate production both in vitro and in vivo, suggesting the inhibition of the Warburg effect. Moreover, this combined treatment induced cell apoptosis and significantly upregulated the levels of proapoptotic proteins, such as Bax, cleaved caspase-3, -7, and -9, and apoptosis-inducing factor. In contrast, levels of the antiapoptotic protein, Bcl-2, were downregulated. Additionally, LKB1 and AMPK activities were stimulated, whereas those of AKT and mTOR were suppressed. Notably, AMPK knockdown abolished the inhibitory effects of capsaicin and cisplatin on the AKT/mTOR signaling pathway and Warburg effect. Overall, combined treatment with capsaicin and cisplatin reversed cisplatin resistance by inhibiting the Warburg effect and facilitating mitochondrial-dependent apoptosis via the AMPK/AKT/mTOR axis. Our findings suggest combination therapy with capsaicin and cisplatin as a potentially novel strategy and highlight capsaicin as a promising adjuvant drug for TSCC treatment.

Plasmonic laser-responsive BioDissolve 3D-printed graphene@cisplatin-implant for prevention of post-surgical relapse of oral cancer

The development of chemoresistance is a major obstacle in post-surgical adjuvant therapy of cancer, leading to cancer cell survival, recurrence, and metastasis. This study reports a 3D-printed plasmonic implant developed for the post-surgical adjuvant therapy of cisplatin-resistant cancer cells to prevent relapse. The implant was printed using optimized biomaterial ink containing biodegradable polymers [poly(L-lactide) and hydroxypropyl methylcellulose] blended suitably with laser-responsive graphene and chemo drug (Cisplatin). The irradiation of scar-driven 3D-printed implant with a laser stimulates graphene to generate a series of hyperthermia events leading to photothermolysis of cisplatin-resistant cancer cells under the combined influence of sustained cisplatin release. The developed personalized implant offers pH-responsive sustained drug release for 28 days. The implant exhibited acceptable biophysical properties (Tensile strength: 3.99 ± 0.15 MPa; modulus: 81 ± 9.58 MPa; thickness: 110 μm). The 3D-printed implant effectively reverses the chemoresistance in cisplatin-resistant 3D spheroid tumor models. Cytotoxicity assay performed using cisplatin-resistant (CisR) cell line revealed that the cell viability was reduced to 39.80 ± 0.68 % from 61.37 ± 0.98 % in CisR tumor spheroids on combined chemo-photothermal therapy. The combination therapy reduced the IC50 value from 71.05 μM to 48.73 μM in CisR spheroids. Apoptosis assay revealed an increase in the population of apoptotic cells (35.45 ± 1.56 % →52.53 ± 2.30 %) on combination therapy. A similar trend was observed in gene expression analysis, where the expression of pro-apoptotic genes Caspase 3 (3.73 ± 0.04 fold) and Bcl-2-associated X protein (BAX) (3.35 ± 0.02 fold) was increased on combination therapy. This 3D-printed, biodegradable implant with chemo-combined thermal ablating potential may provide a promising approach for the adjuvant treatment of resistant cancer.

Identification of a cisplatin resistant-based prognostic immune related gene signature in MIBC

Cisplatin resistance plays a significant role in the dismal prognosis and progression of muscle-invasive bladder cancer (MIBC). However, the strategies to predict prognosis and cisplatin resistance are inefficient, and it remains unclear whether cisplatin resistance is associated with tumor immunity. In this study, we integrated the transcriptional data from cisplatin-resistant cell lines and a TCGA-MIBC cohort to establish cisplatin-resistance-related cluster classification and a cisplatin-resistance-related gene risk score (CRRGRS). Kaplan–Meier survival curves showed that compared with those in low CRRGRS group, MIBC patients belonging to high CRRGRS group had worse prognosis in TCGA-MIBC cohort and external GEO cohorts. Meanwhile, CRRGRS was able to help forecast chemotherapy and immunotherapy response of MIBC patients in the TGCA cohort and IMvigor210 cohort. Moreover, compared with the low CRRGRS group, the high CRRGS group possessed a relatively immunosuppressive “cold tumor” phenotype with a higher tumor immune dysfunction and exclusion (TIDE) score, ESTIMATE score, stromal score and immune score and a lower immunophenoscore (IPS) score. The upregulated expression levels of immune checkpoint genes, including PD-1, PD-L1 and CTLA4, in the high CRRGRS group also further indicated that a relative immunosuppressive tumor microenvironment may exist in MIBC patients belonging to high CRRGRS group. In addition, we integrated CRRGRS and clinical characteristics with prognostic value to develop a nomogram, which could help forecast overall survival of MIBC patients. Furthermore, DIAPH3 was identified as a regulator of proliferation and cisplatin resistance in MIBC. The expression of DIAPH3 was increased in cisplatin-resistant cell lines and chemotherapy-unsensitive people. Further mechanism exploration revealed that DIAPH3 facilitated tumor proliferation and cisplatin resistance by regulating the NF-kB and epithelial-mesenchymal transition (EMT) pathways. In conclusion, the comprehensive investigations of CRRGRS increased the understanding of cisplatin resistance and provided promising insights to restrain tumor growth and overcome chemoresistance by targeting DIAPH3.

(Pentamethylcyclopentadienyl)chloridoiridium(III) Complex Bearing Bidentate Ph2PCH2CH2SPh-κP,κS Ligand.

The (pentamethylcyclopentadienyl)chloridoiridium(III) complex bearing a κP,κS-bonded Ph2PCH2CH2SPh ligand ([Ir(η5-C5Me5)Cl(Ph2P(CH2)2SPh-κP,κS)]PF6, (1)] was synthesized and characterized. Multinuclear (1H, 13C and 31P) NMR spectroscopy was employed for the determination of the structure. Moreover, SC-XRD confirmed the proposed structure belongs to the "piano stool" type. The Hirshfeld surface analysis outlined the most important intermolecular interactions in the structure. The crystallographic structure was optimized at the B3LYP-D3BJ/6-311++G(d,p)(H,C,P,S,Cl)/LanL2DZ(Ir) level of theory. The applicability of this level was verified through a comparison of experimental and theoretical bond lengths and angles, and 1H and 13C NMR chemical shifts. The Natural Bond Orbital theory was used to identify and quantify the intramolecular stabilization interactions, especially those between donor atoms and Ir(III) ions. Complex 1 was tested on antitumor activity against five human tumor cell lines: MCF-7 breast adenocarcinoma, SW480 colon adenocarcinoma, 518A2 melanoma, 8505C human thyroid carcinoma and A253 submandibular carcinoma. Complex 1 showed superior antitumor activity against cisplatin-resistant MCF-7, SW480 and 8505C cell lines. The mechanism of tumoricidal action on 8505C cells indicates the involvement of caspase-induced apoptosis, accompanied by a considerable reduction in ROS/RNS and proliferation potential of treated cells.

Abstract 4488: Newly developed organoiridium(III) complexes containing N,P-ligands possess antiproliferative activity in selected cancer cell lines

Abstract In conventional cancer treatment, platinum-based cytostatics are considered as standard therapy; however, they possess severe side effects. This fact leads to a constant effort to develop new non-platinum metallodrugs with different mechanism of action (MoA). In our study we developed new half-sandwich organoiridium(III) complexes, of general formulas [Ir(η5-Cp*)Cl(LNP)]PF6 (1-3) and [Ir(η5-Cpph)Cl(LNP)]PF6 (4-6) involving three different N,P-donor phosphinoalkylamines (LNP), which we tested on 2D and 3D cancer models; HCp* = pentamethylcyclopentadiene, HCpph= (2,3,4,5-tetramethylcyclopenta-2,4-dien-1-yl)benzene. The most effective complexes 3 and 6 bearing 3-(diphenylphosphanyl)propan-1-amine had the highest cytotoxic effect against various cancer cell lines (THP-1, HeLa, SW982, A549, MOR) including a cisplatin-resistant lung carcinoma cell line (MOR/CPR) with IC50 values between 3.1 and 9.1 μM for specific cell lines. The cytotoxic effect was further demonstrated on 3D spheroids of lung cancer cells that revealed anti-cancer and anti-migration potential of complexes 3 and 6. Cell cycle and cell death analysis showed a different mechanism compared to the effect of cisplatin. Moreover, complex 3 did not decrease cell viability of non-cancerous cells (peripheral blood mononuclear cells and porcine chondrocytes) under 50% at a concentration of 20 µM. In addition, we report for the first time that organoiridium complexes showed high cytotoxic activity on cancer cell lines, including cisplatin-resistant cell line, with different MoA from cisplatin. They trigger expression of stress-related genes associated with oxidative stress, DNA damage, and endoplasmic reticulum stress and, moreover, complex 3 showed cytotoxic selectivity towards cancer cells. This work was supported by the Czech health research council of the Ministry of Health of the Czech Republic (AZV Project NU22-08-00236). Citation Format: Renata Hezova, Jan Hosek, Nicol Strakova, Pavlina Simeckova, Josef Masek, Simona Kajabova, Pavel Starcha. Newly developed organoiridium(III) complexes containing N,P-ligands possess antiproliferative activity in selected cancer cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4488.

Abstract 4561: Mechanism of histone H3K27me3 demethylase therapy for restoring cisplatin sensitivity in refractory testicular cancer

Abstract Testicular germ cell tumors (TGCTs) can be cured at a high rate with standard cisplatin-based chemotherapy, but 15% of metastatic patients are cisplatin resistant/refractory and die from progressive disease. In prior work, we used de novo pharmacogenetic approaches leveraging a series of unique cisplatin resistant cell models that uncovered an important role for polycomb and histone H3K27me3 methylation in mediating TGCT sensitivity and resistance to cisplatin. Importantly, we demonstrated that pharmacological inhibition of H3K27 methylation with the EZH2 inhibitor GSK-126 conferred cisplatin resistance to parental cells while induction of H3K27 methylation with the histone lysine demethylase inhibitor GSK-J4 resulted in a high degree of cisplatin sensitization of TGCT tumors including cisplatin resistant TGCT cells. In order to elucidate mechanisms that account for the remarkable cisplatin sensitization effects of GSKJ4 in TGCTs, we used two distinct cisplatin resistant TGCT cell lines 2102EP-C1 and NT2D1-A4. Cells were pretreated for three days with either vehicle control or 1µM GSK-J4 to modulate H3K27me3 followed by treatment with vehicle control or 0.5µM cisplatin for 6 hours. RNA was extracted from cells after 24 hours of cisplatin removal. This treatment protocol was designed to capture “early” transcriptional responses to GSKJ4 sensitization before the onset of cell death. RNA-seq transcriptomic profiling and differential gene expression analysis revealed as expected a severely attenuated transcriptional response to cisplatin in cisplatin refractory cells that was restored with GSKJ4 pretreatment. Interestingly GSKJ4 alone resulted in a robust transcriptional response with a large overlap with gene changed with cisplatin alone, despite the fact that GSKJ4 alone did not affect cell proliferation or survival. However, GSKJ4 uniquely regulated a subset of genes and uniquely restored cisplatin response to a subset of genes which are candidates for driving the remarkable cisplatin sensitizing effects of GSKJ4 in TGCTs. Further enrichment and biological classification analysis of these distinct gene subsets are ongoing and will be presented. In summary, our data suggests mechanisms to account for why directly targeting H3K27 methylation with GSKJ4 appear highly effective in treating cisplatin resistant/refractory TGCTs and may provide biomarkers for future clinical investigation of this strategy. Citation Format: Doha Naguib Ahmed Mohamed Shokry, Ratnakar Singh, Mehwish Khan, Zeeshan Fazal, Raya Boyd, Christine Powell, Sarah J. Freemantle, Michael J. Spinella. Mechanism of histone H3K27me3 demethylase therapy for restoring cisplatin sensitivity in refractory testicular cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4561.

Abstract 1990: TIP60-mediated acetylation of ΔNp63α is associated with cisplatin resistance

Abstract The chemotherapeutic drug Cisplatin is often used to treat squamous cell carcinoma (SCC) patients, but low response rates and disease recurrence are common. About 5.4 million basal and squamous cell skin cancers are diagnosed each year in the US. ΔNp63α, a member of the p53 family of transcription factors, is overexpressed and considered oncogenic in non-melanoma skin cancer where it regulates cell survival, promotes proliferation, and inhibits cell apoptosis. ΔNp63α has also been shown to promote resistance to cisplatin by orchestrating the transcriptional regulation of several DNA damage response (DDR) genes. Our previous study showed that the histone acetyltransferase (HAT) TIP60 promotes SCC proliferation by positively regulating ΔNp63α protein levels in a manner reliant on the catalytic activity of TIP60. This observation suggested that TIP60 may contribute to the failure of platinum-based drugs in SCC and led us to hypothesize that TIP60-mediated acetylation of ΔNp63α regulates its stability and transcriptional activity to promote chemoresistance. We found that TIP60 levels positively correlated with ΔNp63α stability, protein levels, and cisplatin resistance. Further, silencing endogenous TIP60 led to a decrease in ΔNp63α transcript and protein levels in multiple cisplatin resistant SCC cell lines. Further, stable expression of TIP60 or ΔNp63α individually promoted resistance to cisplatin and reduced cell death, whereas loss of ΔNp63α or TIP60 induced G2/M arrest, increased cell death, and sensitized cells to cisplatin. Additionally, pharmacological inhibition of TIP60 reduced acetylation of ΔNp63α, decreased colony formation, and sensitized resistant cells to cisplatin. Finally, we demonstrated that ΔNp63α and TIP60 levels positively correlated with DNA repair capacity and negatively correlated with cisplatin-DNA adduct formation. Silencing of either TIP60 or ΔNp63α intensified cisplatin-DNA adduct formation and significantly reduced the expression of drug efflux transporters. Taken together, our data indicate that TIP60-mediated stabilization of ΔNp63α increases cisplatin resistance and provides critical insights into the mechanisms by which ΔNp63α confers cisplatin resistance in SCC. Our findings suggest that the inhibition of TIP60 may be therapeutically advantageous in overcoming cisplatin resistance in SCC and other epithelial cancers. Citation Format: Akshay Hira, Jin Zhang, Mike Kemp, Madhavi P. Kadakia. TIP60-mediated acetylation of ΔNp63α is associated with cisplatin resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1990.

Abstract 4639: Unraveling the oncogenic network of USP37 and USP14 in gynecological cancers: Decrypting the molecular landscape of chemoresistance

Abstract Background: Gynecological cancers (GC) involve female reproductive system malignancies, and acquired chemoresistance is a challenge in the treatment of GC. Protein deubiquitination, mediated by deubiquitinating enzymes (DUBs) like ubiquitin-specific proteases (USPs), holds therapeutic promise in cancer treatment. This study delves into the mechanistic understanding of DUBs, particularly in acquired chemoresistance in GC. Methodology: We initially examined TCGA database to assess the impact of Ubiquitin Specific Proteases (USPs), specifically USP37 and USP14, on prognosis in Gynaecological Cancers (GCs). Subsequently, we evaluated their expression in various GC cell lines at both protein and RNA levels. Cell proliferation and metastasis assays were performed to analyze the effect of depleting these USPs on survival and metastasis in GC cells under replication stress. Proteomics analysis was conducted on cells with altered expression of USP37 and USP14 to identify interacting proteins regulating proliferation and metastasis. To investigate DUBs role in chemoresistance, we generated chemoresistant (CR) cell lines with cisplatin exposure, characterized their viability and proliferation, conducted cell cycle and apoptosis analyses, and performed proteomic profiling to explore the USP37 and USP14 specific interactome in chemoresistant cell lines. Results: Examination of TCGA database revealed an association between elevated USP37 and USP14 expression and poor Overall Survival (OS) and Disease-free Survival (DFS) in Gynaecological Cancers (GC) cohort. Increased expression of USP37 and USP14 at RNA and protein levels was observed in GC cell lines. Inhibiting USP37 and USP14 reduced GC cell proliferation under replication stress and hindered metastasis. Proteomics analysis identified proteins linked to replication (PCNA), DNA damage (Chk-1), cell cycle, and metastasis. Cisplatin-resistant GC cell lines were successfully established, demonstrating prolonged survival and increased proliferative capacity after cisplatin treatment compared to chemosensitive (CS) cell lines. FACS analysis indicated altered cell cycle distribution and increased proliferation in CR cells. Comparative interactome analysis revealed altered protein sets associated with USP37 and USP14 in CR and CS GC cells. Conclusion: This study provides evidence that supports the participation of USP37 and USP14 in the onset of gynecological cancers (GC). We present evidence of alterations in the oncogenic network linked to USP37 and USP14 in GC. Additionally, we elucidate the roles of these deubiquitinating enzymes (DUBs) in chemoresistant cell lines. Citation Format: Ravi Chauhan, Ashna Gupta, Gunjan Dagar, Lakshay Malhotra, Ekta Rai, Muzafar A Macha, Ajaz A Bhat, Ethayathulla A Samath, Mayank Singh. Unraveling the oncogenic network of USP37 and USP14 in gynecological cancers: Decrypting the molecular landscape of chemoresistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4639.

Abstract 4671: Efficacy and mechanism of mebendazole for ovarian cancer therapy

Abstract Introduction: Ovarian cancer (OvCa) is the most lethal gynecological malignancy. Although most OvCa patients initially respond to frontline platinum-based therapies with approximately 80% of patients experiencing remission, approximately 75% of those women experience a recurrence with only approximately 50% of patients alive 5 years following diagnosis. There is a critical need to develop novel therapeutic agents or methods to overcome chemoresistance and toxicities experienced with conventional chemotherapy regimens used for OvCa patients. Repurposing drugs is a promising strategy to safely and more rapidly evaluate potentially effective treatment regimens. Over the past two decades, Mebendazole (MBZ), an anti-parasitic drug, has gained much attention in oncology due to its favorable biosafety profile and potent anti-cancerous activity seen in several human malignancies. Therefore, we examined the efficiency and mechanism of MBZ against OvCa. Methods: The in vitro efficacy of MBZ was evaluated in cisplatin-resistant (CPR) and parent (WT/sensitive) OVCAR-8 cell lines as well as in ascites samples collected from chemo-resistant OvCa patients by using 2D and/or 3D cell viability assay and invasion assay. The in vivo efficacy of MBZ was assessed in orthotopic animal models, utilizing CPR-OVCAR8 spheroids, and patient-derived xenograft (PDX) animal models with specimens from chemo-resistant ovarian cancer patients. Molecular mechanisms were investigated through western blot and immunofluorescence analysis. Result: Our results confirmed that MBZ efficiently decreased cell viability, spheroid size, and the invasion ability of OvCa cell lines and ascites samples. OvCa cells treated with MBZ demonstrated downregulation of proliferation markers and upregulation of apoptosis markers indicating inhibition of cell proliferation and induction of apoptosis. Mechanistically, MBZ inhibited the Wnt/β-catenin signaling pathway by downregulating the expression and nuclear localization of β-catenin and epithelial-mesenchymal transition (EMT) markers. Preclinical studies showed that MBZ at 50 mg/kg/day dose for 28 days significantly reduced tumor growth in PDXs and orthotopic tumor models without any evidence of toxicity. Conclusion: Collectively, our study strongly supports the therapeutic potential of MBZ against OvCa particularly, which warrants further clinical studies. Citation Format: Rajani Rai, Dhanamjai Penta, Debasish Dey, Doris M Benbrook, Lin Wang, Magdalena Bieniasz, Lauren E Dockery. Efficacy and mechanism of mebendazole for ovarian cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4671.

Abstract 5872: CDK1-SOX9 axis contributes to chemotherapy resistance in gastric cancer

Abstract Gastric carcinoma (GC) is the third most prevalent cause of cancer-related mortality worldwide, presenting a formidable challenge with the rise of resistance to chemotherapeutic agents, leading to treatment failures. Cyclin-dependent kinase 1 (CDK1) has garnered attention due to its substantial overexpression in various tumors, including GC, and its association with poor overall survival and relapse-free survival. This study aimed to understand the molecular and functional mechanisms underlying the CDK1-SOX9 axis in GC chemotherapy resistance. Through a comprehensive analysis of data from The Cancer Genome Atlas (TCGA) and our own integrated gene expression study, we found a positive correlation between CDK1 and SOX9 in both human and mouse GC tissues (p<0.001). Additionally, conserved alterations in miRNAs have been identified in the context of gastric carcinogenesis, evident in our local cohort and the TCGA dataset. Our in-depth investigation of premiR-145 has shed light on the existence of several CpG nucleotides. Notably, treatment with a DNMT inhibitor (5-Aza) has triggered the upregulation of miR-145 expression. Furthermore, the ectopic expression of CDK1 has been associated with increased DNMT1 phosphorylation and enhanced enzymatic activity. Conversely, silencing CDK1 reversed this effect, and the inhibition of DNMT1 reduced SOX9 protein expression. Using cisplatin-resistant cell lines revealed a significant increase in CDK1 and SOX9 expression where silencing CDK1 and SOX9 sensitized these cells to chemotherapy. This study provides valuable insights into the intricate mechanisms governing the CDK1-SOX9 axis in GC chemotherapy resistance, providing potential avenues for therapeutic interventions in this challenging malignancy. Citation Format: Marwah M. Al-Mathkour, Shoumin Zhu, Melanie Genoula, Wael El-Rifai. CDK1-SOX9 axis contributes to chemotherapy resistance in gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5872.