Cisplatin-resistant Cell Lines Research Articles

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, Fe2+, 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 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 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 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.

Supramolecular nanodrug targeting CDK4/6 overcomes BAG1 mediated cisplatin resistance in oral squamous cell carcinoma

Chemoresistance to cisplatin remains a significant challenge affecting the prognosis of advanced oral squamous cell carcinoma (OSCC). However, the specific biomarkers and underlying mechanisms responsible for cisplatin resistance remain elusive. Through comprehensive bioinformatic analyses, we identified a potential biomarker, BCL2 associated athanogene-1 (BAG1), showing elevated expression in head and neck squamous cell carcinoma (HNSCC). Since OSCC represents the primary pathological type of HNSCC, we investigated BAG1 expression in human tumor tissues and cisplatin resistant OSCC cell lines, revealing that silencing BAG1 induced apoptosis in cisplatin-resistant cells both in vitro and in vivo. This effect led to impaired cell viability of cisplatin resistant OSCC cells and indicated a positive correlation between BAG1 expression and the G1/S transition during cell proliferation. Based on these insights, the administration of a CDK4/6 inhibitor in combination with cisplatin effectively overcame cisplatin resistance in OSCC through the CDK4/6-BAG1 axis. Additionally, to enable simultaneous drug delivery and enhance synergistic antitumor efficacy, we developed a novel supramolecular nanodrug LEE011-FFERGD/CDDP, which was validated in an OSCC orthotopic mouse model. In summary, our study highlights the potential of a combined administration of CDK4/6 inhibitor and cisplatin as a promising therapeutic regimen for treating advanced or cisplatin resistant OSCC.

Mass spectrometry-based proteomic analysis to characterize cisplatin induced early signaling events in head and neck squamous cell carcinoma

ABSTRACT Cisplatin is the commonly used chemotherapeutic drug in treatment of various cancers. However, development of resistance towards cisplatin results in tumor recurrence. Here, we aim to understand the mechanisms of action of cisplatin and emergence of resistance to cisplatin using mass spectrometry-based proteomic approach. A panel of head and neck squamous cell carcinoma (HNSCC) cell lines were treated with cisplatin at respective IC50 for 24 h and label-free mass spectrometry analysis was carried out. Proteomic analysis of A253, FaDu, Det562 and CAL27 cell lines upon cisplatin treatment resulted in the identification of 5,060, 4,816, 4,537 and 4,142 proteins, respectively. Bioinformatics analysis of differentially regulated proteins revealed proteins implicated in DNA damage bypass pathway, translation and mRNA splicing to be enriched. Further, proteins associated with cisplatin resistance exhibited alterations following short-term cisplatin exposure. Among these, class III tubullin protein (TUBB3) was found to be upregulated in cisplatin-treated cells compared to untreated cells. Western blot analysis confirmed the elevated expression of TUBB3 in cells treated with cisplatin for 24 h, and also in cisplatin resistant HNSCC cell lines. This study delineates the early signaling events that enable HNSCC cells to counteract the cytotoxic effects of cisplatin and facilitate the development of resistance.

Targeting cisplatin resistance in breast cancer using a combination of Thymoquinone and Silymarin: an in vitro and in vivo study

Background: Breast cancer (BC) is considered the most diagnosed cancer among women globally. This is because of its high possibility of metastasis and high resistance to chemotherapy. Cisplatin is a platinum-based antitumor agent that is used to treat various types of cancer. However, the main obstacle to using this drug is drug resistance. Drug resistance is a cause of most relapses of cancer which eventually lead to death. Nowadays, combining natural products is a trend to overcome drug resistance. Thymoquinone (TQ) is a natural phytochemical that exists mainly in blackseed. It has been used in medicine for decades, especially as an anticancer agent. Silymarin is a milk thistle compound that exhibits anticancer, hepatoprotective, and neuroprotective activity. Hence, the combination of TQ and silymarin could be a probable solution to treat cancer and reduce chemoresistance. Methods: This study tested this combination on cisplatin-sensitive (EMT6/P) and cisplatin-resistant (EMT6/CPR) mouse mammary cell lines. Apoptotic and antiproliferative activity was assessed for TQ and silymarin in vitro using caspase-3 and [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] (MTT) assays, respectively. An in vivo study was performed to evaluate the effect of TQ and silymarin combination in mice inoculated with EMT6/P and EMT6/CPR cells. The safety profile was also examined using creatinine and liver enzyme assays. Results: In vitro, the TQ and silymarin combination synergized in both cell lines. Also, this combination caused apoptosis induction at a higher rate than the single treatment in both cell lines. In vivo, TQ and silymarin combination resulted in a remarkable reduction in tumor size and enhanced the cure rate in mice implanted with EMT6/P and EMT6/CPR cell lines. According to the safety profile results, TQ and silymarin combination was safe. Conclusion: In conclusion, the combination of TQ and silymarin provides a promising solution in treating BC resistant to cisplatin by inducing apoptosis. Further studies are needed to define the exact anticancer mechanisms of this combination.

Differential modulation of PI3K/Akt/mTOR activity by EGFR inhibitors: A rationale for co-targeting EGFR and PI3K in cisplatin-resistant HNSCC.

To find a new strategy to treat cisplatin-resistant head and neck squamous cell carcinoma (HNSCC), we investigated the effects of EGFR inhibitors on the PI3K/Akt/mTOR pathway and determined the efficacy of EGFR inhibitors in combination with PI3K inhibitors to suppress cell proliferation in cisplatin-resistant-HNSCC. The cisplatin-resistant HNSCC cell lines were treated with four FDA approved EGFR inhibitors, which included Gefitinb or Erlotinib alone, or in combination with the pan-PI3K inhibitor, BKM120. Phosphorylation and total protein levels of cells were assessed by Western blot analysis. Cell proliferation was examined by MTS assay. Apoptosis was analyzed by flow cytometry. Cisplatin-resistant HNSCC cells were also resistant to EGFR inhibitors. However, a combination of EGFR inhibitors with PI3K inhibitor BKM120 dramatically improved the efficacy of EGFR inhibitors to inhibit cell proliferation and induce apoptosis. Furthermore, treatment with EGFR inhibitors differentially affected the phosphorylation of Akt and mTOR, which included partial inhibition, no inhibition, and induction. A combination of EGFR inhibitors and BKM120 completely blocked phosphorylation of EGFR, Akt, and S6K (an mTOR target). Our data provided a rationale for EGFR inhibitors in combination with PI3K inhibitors to treat cisplatin-resistant HNSCC.

PRDX2 regulates stemness contributing to cisplatin resistance and metastasis in bladder cancer.

Cisplatin (CDDP)-based chemotherapy has emerged as the primary treatment for muscle-invasive bladder cancer and metastatic bladder cancer. Nevertheless, a significant proportion of patients experience rapidly developed chemoresistance, leading to treatment ineffectiveness. Existing evidence suggests that chemoresistance is governed by various factors, including tumor stem cells, epithelial mesenchymal transition, and reactive oxygen species (ROS). However, limited research has been conducted on the role of PRDX2, a crucial ROS scavenger, in the modulation of chemoresistance in bladder cancer. Cisplatin-resistant cell lines were established using the concentration gradient overlay method, and differentially expressed genes in resistant cells were screened through RNA sequencing. The expression of PRDX2 in cells and tissues was assessed using RT-qPCR, Western Blot, and immunohistochemistry. The expression of PRDX2 in bladder cancer and adjacent tissues was evaluated using a bladder cancer tissue microarray. Furthermore, the impact of PRDX2 knockdown on tumor formation and metastasis was investigated in vivo by applying subcutaneous tumor xenografts tail vein metastasis assays. We demonstrated that PRDX2 is significantly upregulated in bladder tumors and cisplatin-resistant bladder tumor cell lines. Overexpression of PRDX2 can promote tumor proliferation, migration, and invasion both in vitro and in vivo. We have found that knockdown of PRDX2 expression can effectively reverse cell resistance to cisplatin. Mechanistically, our findings suggest that PRDX2 is involved in regulating tumor stemness and epithelial-mesenchymal transition (EMT). Knockdown of PRDX2 affects the PI3K-AKT and mTOR signaling pathways, thereby influencing tumor stemness and EMT, ultimately impacting the chemotherapy resistance of the tumor. This study provides a new insight into the regulation of chemotherapy resistance in bladder cancer by PRDX2. Targeting PRDX2 can serve as a potent therapeutic target for chemotherapy resistance.

Establishment and characterization of cisplatin-resistant cell lines from canine mammary gland tumors

The development of cisplatin resistance is one of the major causes of mammary cancer treatment failure, and is associated with changes in Sox4 gene expression. To investigate the characteristic changes that occur in canine mammary gland tumor (CMGT) cells following the development of acquired cisplatin resistance, along with the relationship between these changes and the Sox4 gene. We constructed cisplatin-resistant cell line, CHMpCIS, from the cell line CHMp, which was isolated from the primary lesion of a malignant CMGT. The biological characteristics of these cells were examined by Western blot analysis, Transwell assays, and mammosphere formation assays. Compared to CHMp cells, CHMpCIS cells exhibited elevated cisplatin resistance, apoptotic escape ability, enhanced epithelial-mesenchymal transition (EMT) and cancer stem cell (CSC) features, in addition to over-activation of the Wnt/β-catenin signaling pathway and increased Sox4 protein. In CMGT cases, CMGT tissues (CMGTT) expressed higher levels of Sox4 protein and mRNA compared to adjacent tissues (CAMGTT). We found that these changes were inhibited by silencing of Sox4 expression in CHMpCIS cells. Furthermore, activation of the Wnt/β-catenin signaling pathway increased Sox4 expression levels through a positive feedback loop. These results suggested that CHMpCIS cells circumvented the damage caused by cisplatin through altering the expression of the Sox4 gene and activating the Wnt/β-catenin pathway, thereby changing the cellular biological characteristics.

Targeting PAK4 reverses cisplatin resistance in NSCLC by modulating ER stress

Chemoresistance poses a significant impediment to effective treatments for non-small-cell lung cancer (NSCLC). P21-activated kinase 4 (PAK4) has been implicated in NSCLC progression by invasion and migration. However, the involvement of PAK4 in cisplatin resistance is not clear. Here, we presented a comprehensive investigation into the involvement of PAK4 in cisplatin resistance within NSCLC. Our study revealed enhanced PAK4 expression in both cisplatin-resistant NSCLC tumors and cell lines. Notably, PAK4 silencing led to a remarkable enhancement in the chemosensitivity of cisplatin-resistant NSCLC cells. Cisplatin evoked endoplasmic reticulum stress in NSCLC. Furthermore, inhibition of PAK4 demonstrated the potential to sensitize resistant tumor cells through modulating endoplasmic reticulum stress. Mechanistically, we unveiled that the suppression of the MEK1-GRP78 signaling pathway results in the sensitization of NSCLC cells to cisplatin after PAK4 knockdown. Our findings establish PAK4 as a promising therapeutic target for addressing chemoresistance in NSCLC, potentially opening new avenues for enhancing treatment efficacy and patient outcomes.

α-Hederin promotes ferroptosis and reverses cisplatin chemoresistance in non-small cell lung cancer.

Cisplatin is a core chemotherapy regimen in non-small cell lung cancer (NSCLC). However, chemoresistance to cisplatin leads to a poor prognosis in NSCLC. α-Hederin is a natural compound extracted from Nigella sativa. The study aims to explore the effects of α-Hederin on cisplatin resistance in NSCLC. NSCLC cisplatin-resistant cell lines A549/DPP and PC-9 were cultured to evaluate the efficacy of α-Hederin in the treatment of NSCLC in vitro and in vivo. Metabolomics and RNA-seq analysis were used to determine the potential mechanisms of action of α-Hederin. The results showed that α-Hederin inhibited cisplatin-resistant NSCLC cells proliferation and metastasis. Mice xenograft, orthotopic, and metastatic A549/DPP cell models also showed the anti-tumor effects of α-Hederin. The metabolomics and RNA-seq analysis results showed that α-Hederin activated DDIT3/ATF3 pathway and ferroptosis via silencing SLC7A11 and GPX4. Furthermore, α-Hederin enhanced the nuclear expression of EGR1. Bioinformatics and luciferase experiments confirmed that EGR1 binds to the miR-96-5p promoter region, inhibiting transcription. In addition, miR-96-5p directly suppressed the levels of DDIT3. This study revealed that α-Hederin activated EGR1 nuclear translocation and directly repressed miR-96-5p. It also promoted DDIT3/ATF3-mediated ferroptosis and reversed cisplatin resistance in NSCLC.

Histone acetylation: a key determinant of acquired cisplatin resistance in cancer

Cisplatin is an alkylating class of chemotherapeutic drugs used to treat cancer patients. However, cisplatin fails in long-term treatment, and drug resistance is the primary reason for tumor recurrence. Hence, understanding the mechanism of acquirement of chemoresistance is essential for developing novel combination therapeutic approaches. In this study, in vitro cisplatin-resistant cancer cell line models were developed. Gene ontology and GSEA of differentially expressed genes between parental and resistant cells suggest that PI3K-AKT signaling, central carbon metabolism, and epigenetic-associated phenomenon alter in cisplatin-resistant cells. Further, the data showed that increased glucose transport, alteration in the activity of histone-modifying enzymes, and acetyl-CoA levels in resistant cells paralleled an increase in global histone acetylation. Enrichment of histone acetylation on effectors of PI3K-AKT and glycolysis pathway provides evidence of epigenetic regulation of the key molecules in drug resistance. Moreover, cisplatin treatment to resistant cells showed no significant changes in histone acetylation marks since drug treatment alters cell epigenome. In continuation, targeting PI3K-AKT signaling and glycolysis leads to alteration in histone acetylation levels and re-sensitization of resistant cells to chemo-drug. The data provide evidence of histone acetylation's importance in regulating pathways and cisplatin-resistant cells' cell survival. Our study paves the way for new approaches for developing personalized therapies in affecting metabolic pathways and epigenetic changes to achieve better outcomes for targeting drug-resistant cells.