Cisplatin-resistant Tumor Cells Research Articles

TCEB2/HIF1A signaling axis promotes chemoresistance in ovarian cancer cells by enhancing glycolysis and angiogenesis

Ovarian cancer is an extremely malignant gynaecological tumour with a poor patient prognosis and is often associated with chemoresistance. Thus, exploring new therapeutic approaches to improving tumour chemosensitivity is important. The expression of transcription elongation factor B polypeptide 2 (TCEB2) gene is reportedly upregulated in ovarian cancer tumour tissues with acquired resistance, but the specific mechanism involved in tumour resistance remains unclear. In this study, we found that TCEB2 was abnormally highly expressed in cisplatin-resistant tumour tissues and cells. TCEB2 silencing also inhibited the growth and glycolysis of SKOV-3/cisplatin (DDP) and A2780/DDP cells. We further incubated human umbilical vein endothelial cells (HUVECs) with culture supernatants from cisplatin-resistant cells having TCEB2 knockdown. Results revealed that the migration, invasion, and angiogenesis of HUVECs were significantly inhibited. Online bioinformatics analysis revealed that the hypoxia-inducible factor-1A (HIF-1A) protein may bind to TCEB2, and TCEB2 silencing inhibited SKOV-3/DDP cell growth and glycolysis by downregulating HIF1A expression. Similarly, TCEB2 promoted HUVEC migration, invasion, and angiogenesis by upregulating HIF1A expression. In vivo experiments showed that TCEB2 silencing enhanced the sensitivity of ovarian cancer nude mice to cisplatin and that TCEB2 knockdown inhibited the glycolysis and angiogenesis of tumour cells. Our findings can serve as a reference for treating chemoresistant ovarian cancer.

Two-Photon Photodegradation of E3 Ubiquitin Ligase Cereblon by a Ru(II) Complex: Inducing Ferroptosis in Cisplatin-Resistant Tumor Cells.

Using photodynamic therapy (PDT) to trigger nonconventional cell death pathways has provided a new scheme for highly efficient and non-side effects to drug-resistant cancer therapies. Nonetheless, the unclear targets of available photosensitizers leave the manner of PDT-induced tumor cell death relatively unpredictable. Herein, we developed a novel Ru(II)-based photosensitizer, Ru-Poma. Possessing the E3 ubiquitin ligase CRBN-targeting moiety and high singlet oxygen yield of 0.96, Ru-Poma was demonstrated to specifically photodegrade endogenous CRBN, increase lipid peroxide, downregulate GPX4 and GAPDH expression, and consequently induce ferroptosis in cisplatin-resistant cancerous cells. Furthermore, with the deep penetration of two-photon excitation, Ru-Poma achieved drug-resistant circumvention in a 3D tumor cell model. Thus, we describe the first sample of the CRBN-targeting Ru(II) complex active in PDT.

PAX2 mediated upregulation of ESPL1 contributes to cisplatin resistance in bladder cancer through activating the JAK2/STAT3 pathway.

Extra spindle-polar body like 1 (ESPL1) is associated with the development of a variety of cancers, including bladder cancer, and is closely related to chemoresistance. In this study, we aimed to reveal the role of ESPL1 in bladder cancer progression and cisplatin (DDP) resistance. First, ESPL1 was found to be highly expressed in tumor tissues and cells of bladder cancer, and more highly expressed in cisplatin resistant tumor tissues or cells. The binding of PAX2 in ESPL1 promoter region was predicted by Jaspar database and verified by Ch-IP analysis and the luciferase reporter gene assay. Next, cisplatin-resistant T24 cells (T24/DDP) were established and transfected with ESPL1 siRNA (si-ESPL1) or overexpression vector (pcDNA-ESPL1) or co-transfected with PAX2 siRNA (si-PAX2) or overexpression vector (pcDNA-PAX2), and then treated with DDP or AG490, an inhibitor of JAK2. The results showed that silencing ESPL1 significantly reduced T24/DDP cell viability, colony formation and invasion, enhanced sensitivity to DDP, and induced cell apoptosis. Silencing PAX2 decreased ESPL1 expression, enhanced sensitivity to DDP, and induced apoptosis of T24/DDP cells, and inhibited activation of JAK2/STAT3 pathway. Overexpressing ESPL1 reversed the effect of PAX2 silencing on T24/DDP cells, while AG490 counteracted the reversal effect of overexpressing ESPL1. Finally, a xenograft tumor model was established and found that silencing ESPL1 or DDP treatment inhibited tumor growth, while silencing ESPL1 combined with DDP treatment had the best effect. In summary, this study suggested that PAX2-mediated ESPL1 transcriptional activation enhanced cisplatin resistance in bladder cancer by activating JAK2/STAT3 pathway.

Abstract 5386: Increased sprouting angiogenesis in a microphysiological model of cisplatin-resistant recurrent lung cancers

Abstract Non-small cell lung cancer (NSCLC) constitutes 85% of total lung cancer cases and first-line therapies still often employ the platinum-based agents. Cisplatin therapy for NSCLC often leads to relapse of aggressive tumors with high metastatic potential after a period of dormancy. We hypothesize that cisplatin-resistant tumor cell phenotypes will increase features of aggressivity including sprouting angiogenesis in microphysiological models of NSCLC. First, we engineered various TME configurations using A549 cell spheroids and cancer associated fibroblasts (CAF) to establish a baseline of tumor cell proliferation, ECM deposition, and expression of proangiogenic and proinflammatory genes. Next, we generated cisplatin-resistant (Cis-R) A549 sub-lines to test the hypothesis that 3D tumor models engineered using these drug-resistant cells will capture hallmarks of highly aggressive recurrent tumors such as increased expression of progression-associated genes, increased induction of local stromal reactions and more profound angiogenesis. We treated parent A549 with 25 μM cisplatin for 96 hours followed by at least 14 days of recovery to generate Cis-R A549 cells. Interestingly, Cis-R spheroids exhibited significantly lower rates of proliferation (P<0.01) relative to parent A549 spheroids as measured by Ki67 index. Cis-R cells and spheroids exhibit increased genetic expression for genes involved in inflammation, EMT, proliferation and chemoresistance. Furthermore, Cis-R cells in 2D displayed a mesenchymal-like morphology and further exhibited dysmorphic spheroid morphology in 3D. We then developed a membrane free microphysiological system (MPS) comprised of two adjacent and contiguous tissue layers to investigate cancer mediated angiogenesis. We seeded one layer with lung fibroblasts and endothelial cells, which formed a vascularized network, while the other lane was cultured with no cells (control), parent A549 spheroids, or Cis-R A549 spheroids. Media void of VEGF was used throughout the duration of the experiment to isolate the effect of TME-derived factors. We measured increased angiogenetic sprouting induced by Cis-R tissues relative to parent using the following metrics: sprout density (Cis-R = 49.86 ± 10.93 µm/µm2, parent = 13.73 ± 4.12 µm/µm2, blank = 14.76 ± 4.22 µm/µm2), sprout length (Cis-R = 15006 ± 5507 µm, parent = 2466 ± 639.1 µm, blank = 4749 ± 1547 µm), and sprout area fraction (Cis-R = 0.10 ± 0.028, parent = 0.041 ± 0.010, blank = 0.032 ± 0.0095). Thus, the creation of drug resistant tumor cell sub lines enables the construction of more aggressive engineered tumor microenvironments. Future iterations of our MPS model will be used to investigate angiogenesis in the context of additional cancers, including breast and colon, while transitioning to the use of patient-derived organoids. Citation Format: Elisabet Olsen, G. Wills Kpeli, Omar M.K. Ahmad, Mark Mondrinos. Increased sprouting angiogenesis in a microphysiological model of cisplatin-resistant recurrent lung cancers [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 5386.

3D vascularized microphysiological system for investigation of tumor-endothelial crosstalk in anti-cancer drug resistance

Despite the advantages of microfluidic system in drug screening, vascular systems responsible for the transport of drugs and nutrients have been hardly considered in the microfluidic-based chemotherapeutic screening. Considering the physiological characteristics of highly vascularized urinary tumors, we here investigated the chemotherapeutic response of bladder tumor cells using a vascularized tumor on a chip. The microfluidic chip was designed to have open-top region for tumor sample introduction and hydrophilic rail for spontaneous hydrogel patterning, which contributed to the construction of tumor-hydrogel-endothelium interfaces in a spatiotemporal on-demand manner. Utilizing the chip where intravascularly injected cisplatin diffuse across the endothelium and transport into tumor samples, chemotherapeutic responses of cisplatin-resistant or -susceptible bladder tumor cells were evaluated, showing the preservation of cellular drug resistance even within the chip. The open-top structure also enabled the direct harvest of tumor samples and post analysis in terms of secretome and gene expressions. Comparing the cisplatin efficacy of the cisplatin-resistant tumor cells in the presence or absence of endothelium, we found that the proliferation rates of tumor cells were increased in the vasculature-incorporated chip. These have suggested that our vascularized tumor chip allows the establishment of vascular-gel-tumor interfaces in spatiotemporal manners and further enables investigations of chemotherapeutic screening.

Nanomedicines with high drug availability and drug sensitivity overcome hypoxia-associated drug resistance

Tumor hypoxia heterogeneity, a hallmark of the tumor microenvironment, confers resistance to conventional chemotherapy due to insufficient drug availability and drug sensitivity in hypoxic regions. To overcome these challenges, we develope a nanomedicine, NPHPaPN, constructed with hyaluronic acid (HA) grafted with cisplatin prodrug and PEG-azobenzene for hypoxia-responsive PEG shell deshielding and loaded with a DNA damage repair inhibitor (NERi). After arriving at the tumor site, NPHPaPN deshields the PEG shell in response to hypoxia due to the enzymolysis of azobenzene and thus exposes HA. The exposed HA binds to the highly expressed CD44 on cisplatin-resistant tumor cells and mediates drug internalization, thus increasing drug availability to hypoxic tumor cells. After intracellular hyaluronidase-mediated cleavage, the HA NPs release the cisplatin prodrug and NERi, and cause enhanced DNA damage and consequent cell death, thus enhancing the drug sensitivity of hypoxic tumor cells. Eventually, NPHPaPN achieves distinct tumor growth suppression with an ∼84.4% inhibition rate.

Novel Ru(II) complexes with multiple anticancer photoreactivity: ligand exchange, photoredox catalysis, reactive oxygen generation and endoperoxide formation.

The hypoxic microenvironment and drug resistance of cancer cells have become a huge threat for clinical anticancer therapy. Anticancer phototherapy providing spatial and temporal control over drug activation may conquer this problem. Herein, we report a novel photoactivated Ru(II) complex (Ru2) with multiple activities including photochemotherapy, photodynamic and photocatalytic therapy, and endoperoxide formation. Upon white light irradiation, Ru2 can dissociate the coordinating ligands and form endoperoxides, produce diverse reactive oxygen species and catalytically oxidize cellular coenzymes. As a result, Ru2 shows promising antiproliferation activity toward cisplatin and 5-fluorouracil resistant tumor cell lines under normoxia and hypoxia. The multifunctional design strategy of metal-based anticancer drugs offers novel efficient therapeutics to combat drug-resistant cancer cells under hypoxia.

Chiral RuII -PtII Complexes Inducing Telomere Dysfunction against Cisplatin-Resistant Cancer Cells.

The application of G-quadruplex stabilizers presents a promising anticancer strategy. However, the molecular crowding conditions within cells diminish the potency of current G-quadruplex stabilizers. Herein, chiral RuII -PtII dinuclear complexes were developed as highly potent G-quadruplex stabilizers even under challenging molecular crowding conditions. The compounds were encapsulated with biotin-functionalized DNA cages to enhance sub-cellular localization and provide cancer selectivity. The nanoparticles were able to efficiently inhibit the endogenous activities of telomerase in cisplatin-resistant cancer cells and cause cell death by apoptosis. The nanomaterials demonstrated high antitumor activity towards cisplatin-resistant tumor cells as well as tumor-bearing mice. To the best of our knowledge, this study presents the first example of a RuII -PtII dinuclear complex as a G-quadruplex stabilizer with an anti-cancer effect towards drug-resistant tumors inside an animal model.

Abstract 2349: SAP30, a novel drug response specific transcription factor in high-risk neuroblastoma

Abstract Neuroblastoma is the most devastating extracranial solid malignancy in children. Despite an intense treatment regimen, the prognosis for high-risk neuroblastoma patients remains poor, with less than 40% survival. So far, MYCN status/amplification is considered the most prognostic factor but corresponds to only 25% of neuroblastoma patients. Therefore, it is essential to identify a better prognosis and prediction marker of therapy response in neuroblastoma patients. The identification of master regulators with good prognostic and drug response abilities are not successful due to the complexity and lack of data-driven bioinformatic workflows. We applied robust bioinformatic data mining tools such as Weighted Gene Co-expression Network Analysis, cisTarget, and Single-Cell rEgulatory Network Inference and Clustering on three neuroblastoma patient datasets (n=1252). We found Sin3A Associated Protein 30 (Sap30), a driver transcription factor positively associated with high-risk, progression, stage 4, and poor survival in high-risk neuroblastoma patient cohorts. Tumors of high-risk neuroblastoma patients and relapse-specific patient-derived xenografts showed higher Sap30 levels. The Genomics of Drug Sensitivity in Cancer, The Cancer Cell Line Encyclopedia, and CRISPR-Cas9 screens indicated that Sap30 essentiality is associated with Cisplatin resistance and further showed higher levels in Cisplatin resistant patient-derived xenograft tumor cell lines. The silencing of Sap30 in cells reduced cell growth, induced cell death, mitochondrial membrane potential loss in vitro, and reduced tumorigenicity in vivo. Altogether, these results indicate that Sap30 is a novel prognostic and Cisplatin resistant marker and thus a potential drug target in high-risk neuroblastoma patients. Citation Format: Philip Prathipati, Anup S. Pathania, Nagendra K. Chaturvedi, Subash C. Gupta, Siddappa N. Byrareddy, Don W. Coulter, Kishore B. Challagundla. SAP30, a novel drug response specific transcription factor in high-risk neuroblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2349.

Abstract 1073: Preclinical tissue biodistribution and plasma pharmacokinetic studies with oxaliTEX, a novel platinum(IV)-based oxaliplatin prodrug

Abstract Purpose: OxaliTEX is a texaphyrin-platinum(IV) prodrug with the ability to deliver the oxaliplatin payload to cisplatin-resistant tumor cells and restore wild-type p53 activation. As a result, the conjugate overcomes both multifactorial mechanisms of cisplatin resistance and transport-defective mechanism of oxaliplatin resistance. In an effort to prepare for translational studies, we have explored its distribution and pharmacokinetics (PK) in mice. Experimental Procedures: Athymic male and/or female nude mice (3-4/group), with or without subcutaneously implanted (flank) HCT-116 colon xenograft, received oxaliplatin (4 mg/kg) and an equimolar (17 mg/kg) or a similar therapeutic (50 mg/kg) dose of oxaliTEX iv. After 24 hours, mice were exsanguinated under anesthesia and plasma and tissues isolated. A separate group of female mice received oxaliTEX (50 mg/kg) and blood was taken at multiple times over the next 24 hours, plasma isolated and samples denatured to prepare protein-free supernatant (PFS) representing “free” platinum. Samples were analyzed for platinum (Pt) by flameless atomic absorption spectrophotometry. Results: At equimolar doses, gross sex differences in plasma or tissue concentrations were not observed for either drug. However, plasma Pt levels with oxaliTEX (0.6-0.7 ng Pt/ml) were 7-fold greater than with oxaliplatin (0.08-0.1 ng/ml). Similarly, a 3-fold greater concentration was also noted in liver (~1.4 vs. ~0.4 ng/mg) and heart (~0.5 vs. ~0.15 ng/mg) from mice treated with the prodrug. Tissues with ≤2-fold differences between the drugs in Pt levels were testes, kidney, ovary, lung, ileum and spleen, with undetectable levels in brain. In female mice bearing HCT-116 xenografts, the general tissue distribution pattern of each drug at the therapeutic dose was unchanged and demonstrated that increasing the oxaliTEX dose resulted in proportionate increase in tissue Pt levels. Notably, tumor Pt levels were ~5-fold greater with the conjugate (oxaliTEX, 1.1 ng Pt/mg; oxaliplatin, 0.21 ng/mg). PK analysis revealed that Pt in plasma and PFS was detectable for the entire 24 hr period and decayed in a biphasic manner, with respective α-phase half-life of 0.07 and 0.2 hr and β-phase half-life of 27 and 11 hr. The AUC in plasma and PFS was 172 and 3.7 μg.hr/ml, respectively. Conclusions: Results suggest that oxaliTEX is sequestered in the plasma by protein binding, leaving low-level systemic exposure to “free” non-protein bound Pt. Since the tissue levels are greater than oxaliplatin at equimolar and/or therapeutic doses in specific organs, this suggests that the low level exposure to “free” Pt contributes to drug tolerance of normal tissues, whereas the tumor-targeting design feature contributes to greater tumor uptake that enhances antitumor effects. Funding was provided by Cancer Prevention and Research Institute of Texas Citation Format: Guangan He, Gregory Thiabaud, Kathyrin A. Shelton, Luke J. Segura, Jonathan L. Sessler, Rick A. Finch, Zahid H. Siddik, Jonathan F. Arambula. Preclinical tissue biodistribution and plasma pharmacokinetic studies with oxaliTEX, a novel platinum(IV)-based oxaliplatin prodrug [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1073.

Apoptotic Effect of Homobrassinin and Thiazino[6,5-b]indol is Associated with Downregulation of Heat Shock Proteins in Human Ovarian Adenocarcinoma Cells

Phytoalexins are substances with antimicrobial properties produced by plants after being attacked by microorganisms, especially phytopathogenic fungi and viruses. They are also currently being studied for their antitumor effect. We aimed to study the apoptosis-stimulating effect of homobrassinin and thiazino[6,5-b]indol in human ovarian adenocarcinoma A2780 and A2780cis cells via flow cytometric analysis of annexin V/PI, caspase 3 and 9 activity, cytochrome C release, and smac-diablo accumulation. Using the western blot technique, we also monitored the effect of both indoles on the response of heat shock proteins in these cells. Thiazino[6,5-b]indol showed more pronounced sensitizing and/or pro-apoptotic effect compared to homobrassinin accompanied by increased smac-diablo accumulation at earlier time intervals and pronounced externalization of phosphatidylserine at 72 h in A2780cis compared to A2780 cells. The apoptosis stimulating effect of thiazino[6,5-b]indol in A2780cis cells was associated with significant irreversible downregulation of HSP70 and HSP90 and partly with a decrease of HSP40. On the other hand, cisplatin-induced the apoptosis of sensitive A2780 cells with reversible downregulation of HSP40 and HSP57. In conclusion, the effect of thiazino[6,5-b]indol on resistant A2780cis cells could have a great utility in both the potential prevention and the treatment of other cisplatin-resistant tumor cells.

LncRNA LHFPL3-AS1 Promotes Oral Squamous Cell Carcinoma Growth and Cisplatin Resistance Through Targeting miR-362-5p/CHSY1 Pathway

BackgroundOral squamous cell carcinoma (OSCC) is a common oral cancer. The current study aims to elucidate the potential roles of long noncoding RNA (lncRNA) LHFPL3-AS1 in OSCC development.MethodsGene expression was measured by qRT-PCR in tumor tissues and cell lines. Loss-of-function assays were performed to analyze the effects of LHFPL3-AS1 on malignant behaviors. Bioinformatics analysis was conducted to explore the downstream signaling pathway of LHFPL3-AS1 in OSCC.ResultsLHFPL3-AS1 was highly expressed in OSCC tissues and cell lines. LHFPL3-AS1 was upregulated in cisplatin-resistant tumor cell lines. LHFPL3-AS1 level was correlated with survival rate. LHFPL3-AS1 knockdown suppressed OSCC proliferation, migration and invasion. LHFPL3-AS1 downregulation reduced cisplatin resistance of OSCC cells. LHFPL3-AS1 was the competing endogenous RNA (ceRNA) for miR-194-5p to enhance CHSY1 expression.ConclusionLHFPL3-AS1/miR-362-5p/CHSY1 signaling pathway plays essential roles in regulating OSCC development and cisplatin resistance.

Iridium(iii) complexes as mitochondrial topoisomerase inhibitors against cisplatin-resistant cancer cells.

Herein, we developed the first metal-based mitochondrial topoisomerase inhibitors to achieve an effective therapeutic outcome for the therapy of cisplatin-resistant tumour cells.

3-MA Enhanced Chemosensitivity in Cisplatin Resistant Hypopharyngeal Squamous Carcinoma Cells via Inhibiting Beclin -1 Mediated Autophagy

Hypopharyngeal carcinoma is characterized by a high degree of malignancy. The most common pathological type is squamous cell carcinoma (HSCC). Cisplatin (cis-diamminedichloroplatinum, CDDP) is one of the most widely used chemotherapeutic drugs nowadays and cisplatin resistance is a major problem in current treatment strategies. Clinical researchers have reported that high autophagy levels often caused insensitivity to chemotherapy, a common phenomenon that greatly reduces the therapeutic effect in cisplatin- resistant tumor cell lines. 3-methyladenine (3-MA), an inhibitor of PI3K, plays a vital role in forming and developing autophagosomes. Therefore, we speculate that the use of 3-MA may reduce cisplatin resistance in hypopharyngeal squamous cell carcinoma (HSCC). Part I: Cisplatin-resistant FaDu cell line (Human hypopharyngeal squamous cell carcinoma cells) was established and cultured. Cell counting kit-8 was used to detect drug resistance. An inverted microscope was used to observe the morphological changes at different concentrations, then the survival rate was calculated. After MDC staining, the autophagic vacuoles were observed by fluorescence microscopy. The expression of Beclin1 from each group was confirmed by RT-PCR and Western blot method. Part II: 3-MA was applied for cisplatin-resistant cells intervention, Beclin1 was knocked down by plasmid transfection. Cell cycle was detected using flow cytometry assay, apoptosis with necrosis was detected by staining with propidium iodide (PI). CCK-8 was used to observe the cell survival rate in each group. The expression of autophagy-related protein Beclin1, LC3I, LC3II, Atg-5 and P62 in each group was verified by Western blot analysis. Cisplatin-resistant FaDu cell line can be stably constructed by cisplatin intervention. Compared with normal group, autophagy and its related protein Beclin1 expression were enhanced in cisplatin resistant FaDu cells. Autophagy inhibition group showed significant cell cycle changes, mainly manifested by G1 arrest, increased apoptosis rate and significantly decreased survival rate at 24h level. The number of autophagy vacuoles were significantly reduced in the 3-MA group. Furthermore, Western blot showed that expression of Beclin1, lc3-I, lc3-II, atg-5 protein decreased significantly after 3-MA intervention, while the expression of p62 upregulated, which also confirmed autophagy flow was blocked. Our work confirmed that enhanced autophagy is an important cause of cisplatin resistance in FaDu cells. The use of 3-MA can significantly reduce autophagy level and arresting its cell cycle, promote apoptosis and reverse the cisplatin resistance condition, this effect is partly mediated by inhibition of Beclin-1 expression. Our data provide a theoretical basis for the application of 3-MA in overcoming cisplatin resistance in hypopharyngeal cancer.

Chemotherapeutic resistance of head and neck squamous cell carcinoma is mediated by EpCAM induction driven by IL-6/p62 associated Nrf2-antioxidant pathway activation

Overexpression of epithelial cell adhesion molecule (EpCAM) has been associated with chemotherapeutic resistance, leads to aggressive tumor behavior, and results in an adverse clinical outcome. The molecular mechanism by which EpCAM enrichment is linked to therapeutic resistance via Nrf2, a key regulator of antioxidant genes is unknown. We have investigated the link between EpCAM and the Nrf2 pathway in light of therapeutic resistance using head and neck squamous cell carcinoma (HNSCC) patient tumor samples and cell lines. We report that EpCAM was highly expressed in Nrf2-positive and HPV-negative HNSCC cells. In addition, cisplatin-resistant tumor cells consisted of a higher proportion of EpCAMhigh cells compared to the cisplatin sensitive counterpart. EpCAMhigh populations exhibited resistance to cisplatin, a higher efficiency in colony formation, sphere growth and invasion capacity, and demonstrated reduced reactive oxygen species (ROS) activity. Furthermore, Nrf2 expression was significantly higher in EpCAMhigh populations. Mechanistically, expression of Nrf2 and its target genes were most prominently observed in EpCAMhigh populations. Silencing of EpCAM expression resulted in the attenuation of expressions of Nrf2 and SOD1 concomitant with a reduction of Sox2 expression. On the other hand, silencing of Nrf2 expression rendered EpCAMhigh populations sensitive to cisplatin treatment accompanied by the inhibition of colony formation, sphere formation, and invasion efficiency and increased ROS activity. The molecular mechanistic link between EpCAM expression and activation of Nrf2 was found to be a concerted interaction of interleukin-6 (IL-6) and p62. Silencing of p62 expression in EpCAMhigh populations resulted in the attenuation of Nrf2 pathway activation suggesting that Nrf2 pathway activation promoted resistance to cisplatin in EpCAMhigh populations. We propose that therapeutic targeting the Nrf2-EpCAM axis might be an excellent approach to modulate stress resistance and thereby survival of HNSCC patients enriched in EpCAMhigh populations.

Protein expression profiling identifies differential modulation of homologous recombination by platinum-based antitumor agents.

Oxaliplatin and satraplatin demonstrate activity against cisplatin-resistant tumor cells. Although the two platinum analogs are structurally-related, oxaliplatin is more active. Therefore, studies focusing on protein expression profiling were undertaken to identify the molecular mechanism for the difference in antitumor activity. We included cisplatin as reference and DAP as a Pt(IV)-prodrug of oxaliplatin to offset Pt(IV) status of satraplatin, and utilized A2780, cisplatin-resistant 2780CP/Cl-16, U2OS, and HCT-116 tumor cells in the investigation. Protein expressions following drug exposures were examined by reverse-phase protein array and ingenuity pathway analysis. Cell cycle was assessed by flow cytometry, cytotoxicity by growth inhibition assay, and homologous recombination (HR) by a GFP reporter assay. Clustering analysis paired oxaliplatin with DAP and, surprisingly, satraplatin with cisplatin. This correlated with differential upregulation of p53/p21 pathway, with S and G2/M arrests by cisplatin and satraplatin in contrast to G1 arrest by oxaliplatin and DAP. Moreover, Rad51 and BRCA1 were severely downregulated by oxaliplatin and DAP, but not cisplatin and satraplatin. As a result, HR was inhibited only by oxaliplatin and DAP and this also contributed to their greater drug activity over cisplatin and satraplatin. Oxaliplatin and DAP robustly activate p53 and p21, which downregulate HR proteins to enhance drug activity. More significantly, since oxaliplatin induces a BRCAness state, it may have potential against BRCA-proficient cancers. Satraplatin, on the other hand, resembled cisplatin in its protein expression profile, which indicates that small changes in chemical structure can substantially alter signal transduction pathways to modulate drug activity.

Effect of N,N Coordination and RuII Halide Bond in Enhancing Selective Toxicity of a Tyramine-Based RuII (p-Cymene) Complex.

Ruthenium compounds are promising anticancer candidates owing to their lower side-effects and encouraging activities against resistant tumors. Half-sandwich piano-stool type RuII compounds of general formula [(L)RuII(η6-arene)(X)]+ (L = chelating bidentate ligand, X = halide) have exhibited significant therapeutic potential against cisplatin-resistant tumor cell lines. In RuII (p-cymene) based complexes, the change of the halide leaving group has led to several interesting features, viz., hydrolytic stability, resistance toward thiols, and alteration in pathways of action. Tyramine is a naturally occurring monoamine which acts as a catecholamine precursor in humans. We synthesized a family of N,N and N,O coordinated RuII (p-cymene) complexes, [(L)RuII(η6-arene)(X)]+ (1-4), with tyramine and varied the halide (X = Cl, I) to investigate the difference in reactivity. Our studies showed that complex 2 bearing N,N coordination with an iodido leaving group shows selective in vitro cytotoxicity against the pancreatic cancer cell line MIA PaCa-2 (IC50 ca. 5 μM) but is less toxic to triple-negative breast cancer (MDA-MB-231), hepatocellular carcinoma (Hep G2), and the normal human foreskin fibroblasts (HFF-1). Complex 2 displays stability toward hydrolysis and does not bind with glutathione, as confirmed by 1H NMR and ESI-HRMS experiments. The inert nature of 2 leads to enhancement of cytotoxicity (IC50 = 5.3 ± 1 μM) upon increasing the cellular treatment time from 48 to 72 h.

Inhibition of cisplatin-resistant tumor cells on activated CD4+ T cells in ovarian cancer and its mechanism

Objective: To investigate the inhibition of cisplatin-resistant tumor cells on activated CD4+ T cells in ovarian cancer and its mechanism. Methods: 50 patients with ovarian cancer admitted to our hospital from March 2016 to July 2017 were selected as the research group, and 50 normal subjects were selected as the control group. The same separation method of CD4+ T cells was applied to both two groups. The serum levels of ovarian cancer markers and inflammation factors were compared between two groups. Results: The serum levels of ovarian cancer markers in the research group were higher than those in the control group (P<0.05). The average proportion of CD4+ T cells in peasant patients was higher than that in workers and cadres (P<0.05). The average proportion of CD4+ T cells in patients with tumor infiltration was higher than that in patients without infiltration (P<0.05). The level of IL-6 in the research group was higher than that in the control group. While the levels of IL-10, IL-4, IL-2, TNF-α and IFN-γ were lower than those in the control group (P<0.05), and the immune function of the research group was still lower than that of the control group (P<0.05). Conclusion: Cisplatin-resistant ovarian cancer cells can inhibit the activation of CD4+ T cells, which can effectively judge the different stages of ovarian cancer. Moreover, the number of CD4+ T cells can be used to determine the prognosis of patients, providing a certain clue for clinical treatment.

A mitochondria-targeting dinuclear Ir-Ru complex as a synergistic photoactivated chemotherapy and photodynamic therapy agent against cisplatin-resistant tumour cells.

A mitochondria-targeting hetero-binuclear Ir(iii)-Ru(ii) complex was developed as a photoactivated chemotherapy (PACT) and photodynamic therapy (PDT) bifunctional agent to achieve a synergistic effective therapeutic outcome for the therapy of cisplatin-resistant tumour cells.

Abstract NTOC-081: PHARMACOLOGIC ANALYSIS OF HIGH–GRADE SEROUS OVARIAN CANCER TCGA DATASET IDENTIFIES A NOVEL CHEMO–ADJUVANT ROLE FOR NON–STEROIDAL ANTI–INFLAMMATORY DRUGS (NSAIDS)

Abstract Computation-based drug repositioning approaches that automatically search vast amounts of genomic-chemical-phenotypic data for tens of thousands of drugs and diseases can greatly speed up the traditional drug-discovery process. To date, systematic and comprehensive computation-based approaches to identify and validate drug repositioning candidates for High-grade serous ovarian cancer (HGSOC) have not been undertaken. Using a novel computational drug-repositioning platform (Drug-Predict) with HGSOC gene expression dataset from The Cancer Genome Atlas (TCGA) as the input, we have uncovered that Non-steroidal anti-inflammatory drugs (NSAIDs) could be potential candidates for Drug repositioning in HGSOC. Given that numerous epidemiological studies have shown that regular intake of NSAIDs in women is associated with decreased incidence of ovarian cancer, we assessed whether NSAIDs could have chemo-adjuvant applications in HGSOC and have identified Indomethacin as a novel chemo-adjuvant in HGSOC. Indomethacin decreased survival of primary HGSOC tumor cells and interestingly, cisplatin resistant ovarian tumor cells (derived from primary HGSOC PDX models) exhibited significantly higher cell death upon Indomethacin treatment suggesting that Indomethacin could exert chemo-adjuvant effects in HGSOC. Accordingly, Indomethacin treatment induced chemo-sensitivity in cisplatin resistant HGSOC tumor cells and combo treatment with Indomethacin and cisplatin exerted synergistic cell death as compared to individual drugs alone. Furthermore, Indomethacin decreased stem-like properties and induced chemo-sensitivity in ALDHhigh cisplatin-resistant tumor-initiating cells (TICs) thus suggesting that the chemo-adjuvant effect of the drug is mediated by decrease in TIC properties in HGSOC cells. Mechanistically, we found that Indomethacin inhibits Wnt/β-catenin signaling by degrading β-catenin and β-catenin modulation inversely affected Indomethacin functioning in HGSOC. Our study is the first report describing functional effects of an NSAID in patient-derived HGSOC models and demonstrates that combining novel computational predictions with experimental validation has potential in identifying viable drug candidates and moving them into patient trials efficiently and cost-effectively. Since NSAIDs are in routine clinical use in gynecological settings and have acceptable safety profile, this discovery provides with a potentially rapid and cost-effective translational opportunity for testing NSAIDs as chemo-adjuvants in patient trials in HGSOC. Citation Format: Anil Belur Nagaraj, QuanQiu Wang, Olga Kovalenko, Peronne Joseph, Yang Chen, Rong Xu and Analisa DiFeo. PHARMACOLOGIC ANALYSIS OF HIGH–GRADE SEROUS OVARIAN CANCER TCGA DATASET IDENTIFIES A NOVEL CHEMO–ADJUVANT ROLE FOR NON–STEROIDAL ANTI–INFLAMMATORY DRUGS (NSAIDS) [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr NTOC-081.