Cisplatin Toxicity Research Articles

Beneficial effects of β-glucan against cisplatin side effects on the nervous system in rats 1.

To investigate the protective effect of Bg on cisplatin (CP)-induced neurotoxicity in rats. Twenty eight rats were randomly distributed into four groups. The first group was kept as a control. In the second group, CP was given at the single dose of 7 mg/kg intraperitoneally. In the third group, βg was orally administered at the dose of 50 mg/kg/day for 14 days. In the fourth group, CP and βg were given together at the same doses. CP treatment caused significant oxidative damage via induction of lipid peroxidation and reductions antioxidant defense system potency in the brain tissue. In addition, histopathological damage increased with CP treatment. On the other hand, βg treatment largely prevented oxidative and histopathological negative effects of CP. Cisplatin has severe neurotoxic effects in rats and βg supplementation has significant beneficial effects against CP toxicity depending on its antioxidant properties. Thus, it appears that βg might be useful against CP toxicity in patients with cancer in terms of nervous system.

Combining disulfiram and poly(l-glutamic acid)-cisplatin conjugates for combating cisplatin resistance

A poly(l-glutamic acid) graft polyethylene glycol-cisplatin complex (PGA-CisPt) performs well in reducing the toxicity of free cisplatin and greatly enhances the accumulation and retention of cisplatin in solid tumors. However, there is a lack of effective treatment options for cisplatin-resistant tumors. A major reason for this is the dense PEG shell, which ensures that the PGA-CisPt maintains a long retention time in the blood that may result in it bypassing the tumor cells or failing to be endocytosed within the tumor microenvironment. Consequently, the cisplatin from PGA-CisPt is released to the extracellular space in the presence of cisplatin-resistant tumor cells and the resistant problem to free cisplatin still valid. Therefore, we devised a strategy to combat the resistance of cisplatin in the tumor microenvironment using nanoparticles-loaded disulfiram (NPs-DSF) as a modulator. In vitro, cisplatin, in combination with DSF, had a synergistic effect and decreased cell survival rate of cisplatin-resistant A549DDP cells. This effect was also observed when combining PGA-CisPt with NPs-DSF. Similarly, in Balb/C nude mice with A549DDP xenografts, NPs-DSF improved PGA-CisPt effectiveness in inhibiting tumor growth while maintaining low toxicity. Our data demonstrate that DSF reduces intracellular glutathione (GSH) levels, inhibits NFκB activity, and modulates the expression of apoptosis-related proteins Bcl-2 and Bax, thereby improves the effectiveness of cisplatin in resistant cell lines. Here, we provide a promising method for overcoming cisplatin resistance in tumors, while maintaining the in vivo benefits of the PGA-CisPt complex.

MiR-145 sensitizes gallbladder cancer to cisplatin by regulating multidrug resistance associated protein 1.

Gallbladder cancer (GBC) is the most common malignancy in biliary tract with poor prognosis. Due to its high chemoresistance, systemic chemotherapies have had limited success in treating GBC patients. MicroRNAs (miRNAs) are emerging novel regulators of chemoresistance, which modulate the expression of drug resistance-related genes. In this study, we investigated the association between miR-145 expression and cisplatin sensitivity by both in vivo and in vitro analysis. Quantitative PCR (q-PCR) analysis indicated an increased miR-145 expression in GBC tissues. In addition, studies on GBC cell lines suggested an increased cisplatin efficacy with miR-145 overexpression, whereas decreasing miR-145 expression reduced cisplatin sensitivity. Further, we found that miR-145 accelerated MRP1 mRNA degradation by directly targeting its 3'-UTR and therefore caused increased cisplatin toxicity in GBC cells. Moreover, lower miR-145 and higher MRP1 expression levels predicted poor prognosis in GBC patients who received chemotherapy. Collectively, our findings established a rationale for using miR-145 expression as a biomarker to identify cisplatin-resistant GBC patients and propose that treatment strategies increasing the expression of miR-145 could be a new therapeutic approach for GBC patients.

Toxicity of the mixture of selected antineoplastic drugs against aquatic primary producers.

The residues of antineoplastic drugs are considered as new and emerging pollutants in aquatic environments. Recent experiments showed relatively high toxicity of 5-fluorouracil (5-FU), imatinib mesylate (IM), etoposide (ET) and cisplatin (CP) that are currently among most widely used antineoplastic drugs, against phytoplankton species. In this study, we investigated the toxic potential of the mixture of 5-FU + IM + ET against green alga Pseudokirchneriella subcapitata and cyanobacterium Synechococcus leopoliensis, and the stability and sorption of these drugs to algal cells. Toxic potential of the mixture was predicted by the concepts of 'concentration addition' and 'independent action' and compared to the experimentally determined toxicity. In both test species, the measured toxicity of the mixture was at effects concentrations EC10-EC50 higher than the predicted, whereas at higher effect concentration (EC90), it was lower. In general, P. subcapitata was more sensitive than S. leopoliensis. The stability studies of the tested drugs during the experiment showed that 5-FU, IM and CP are relatively stable, whereas in the cultures exposed to ET, two transformation products with the same mass as ET but different retention time were detected. The measurements of the cell-linked concentrations of the tested compounds after 72h exposure indicated that except for CP (1.9% of the initial concentration), these drugs are not adsorbed or absorbed by algal cells. The results of this study showed that in alga and cyanobacteria exposure to the mixture of 5-FU + ET + IM, in particular at low effect concentration range, caused additive or synergistic effect on growth inhibition, and they suggest that single compound toxicity data are not sufficient for the proper toxicity prediction for aquatic primary producers.

A meta-analysis comparing cisplatin-based to carboplatin-based chemotherapy in moderate to advanced squamous cell carcinoma of head and neck (SCCHN)

PurposeThis study was performed to compare the efficacies and toxicities of cisplatin (CDDP)- and carboplatin (CBDCA)-based chemotherapy (CT) in patients with SCCHN.MethodsThe search strategy included Pubmed, Science Direct, the Cochrane Library, and the China National Knowledge Internet Web. Statistical analyses were performed using RevMan 5.2. The primary endpoint was overall survival (OS) with secondary endpoints of locoregional control (LRC) and grade≥3 toxicity.ResultsOverall, 12 studies and 1165 patients were included. CDDP-based CT significantly improved 5-year OS (HR=0.67, 95% CI, 0.49 to 0.91; P=0.01) compared to the CBDCA group. No difference in the 3-year OS/LRC was observed, but a subgroup analysis showed a better 3-year OS in the CDDP arm for non-nasopharynx carcinoma (non-NPC) SCCHN (HR=0.66, 95% CI, 0.48 to 0.91; P=0.01). The CDDP-based CT was associated with more gastrointestinal toxicities (RR=4.58; P=0.005) and nephrotoxicity (4/110=3.6%) compared to the CBDCA group, but fewer anemia, leukopenia and thrombocytopenia with RRs of 0.27, 0.71, and 0.28 respectively.ConclusionsPatients with CDDP-based CT can achieve a higher OS, but there is no significant difference in LRC. The CDDP-based CT is associated with fewer hematological toxicities but more gastrointestinal toxicities and nephrotoxicity compared to the CBDCA arm.

Carvedilol protects the kidneys of tumor-bearing mice without impairing the biodistribution or the genotoxicity of cisplatin

Cisplatin (Cisp) is an effective antitumor drug; however, it causes severe nephrotoxicity. Minimization of renal toxicity is essential, but the interference of nephroprotective agents, particularly antioxidants, with the antitumor activity of cisplatin is a general concern. We have recently demonstrated that the anti-hypertensive and antioxidant drug carvedilol (CV) protects against the renal damage and increases the survival of tumor–bearing mice without impairing the tumor reduction by cisplatin. So far, reports on the antioxidant mechanism of CV are controversial and there are no data on the impact of CV on the antitumor mechanisms of cisplatin. Therefore, this study addresses the effect of CV on mechanisms underlying the tumor control by cisplatin. CV did not interfere with the biodistribution or the genotoxicity of cisplatin. We also addressed the antioxidant mechanisms of CV and demonstrated that it does not neutralize free radicals, but is an efficient chelator of ferrous ions that are relevant catalyzers in cisplatin nephrotoxicity. The present data suggest that oxidative damage and genotoxicity play different roles in the toxicity of cisplatin on kidneys and tumors and therefore, some antioxidants might be safe as chemoprotectors. Altogether, our studies provide consistent evidence of the beneficial effect of CV on animals treated with cisplatin and might encourage clinical trials.

EVALUATION OF EFFICACY AND TOXICITY OF NEOADJUVANT CHEMOTHERAPY WITH DOSE-DENSE DOXORUBICIN, CISPLATIN, AND PACLITAXEL IN PATIENTS WITH EARLY TRIPLE-NEGATIVE BREAST CANCER

Triple-negative breast cancer (TNBC) is characterized by an aggressive behavior, highly sensitivity to chemotherapy, early recurrence, and also the absence of known targets for targeted therapies. TNBC is extremely impotant search for intensive regimens of neoadjuvant chemotherapy, because of insufficient effectiveness of conventional therapies. The aim of the study was to evaluate the efficacy and toxicity of cisplatin, doxorubicin, paclitaxel in patients with early breast cancer with triple-negative phenotype in preoperative mode. The study included 41 patients with early breast cancer, triple negative phenotype (T1–2 N0–1M0). Patients were treated with cisplatin 30 mg/m2 / IV., Doxorubicin 25 mg/m2 / IV., Paclitaxel 100 mg/m2 / IV. weekly for planned 8 weeks with G-CSF 300 mcg 2–4 days followed by surgery. The rate of objective response was 38/40 (95%) complete response – 12/40 (30%), partial regression – 26/40 (65%), stabilization – 2/40 (50%). 40 hftients were treated with surgery, 26/40 (65%) achieved a complete pathological regression. 2-year disease-free survival – 89.4%. 2-year overall survival – 95.1%. Combination of cisplatin, doxorubicin, paclitaxel, it proved its high efficacy in patients with early breast cancer with triple-negative phenotype, despite it’ high toxicity.

Comment on: Effect of Pomegranate Flower Extract on Cisplatin-induced Nephrotoxicity in Male Rats.

DEAR EDITOR, I read with interest a recently published article in the “Journal of Nephropathology” by Motamedi et al., entitled “Effect of pomegranate flower extract on cisplatin-induced nephrotoxicity in male rats.”[1] The authors have concluded that low dose of pomegranate flower extract (PFE) (25 mg/kg) showed protective effects against cisplatin (CP)-induced nephrotoxicity through its antioxidant effects. On the other hand, they did not observed the protective role of a higher dose of PFE (50 mg/kg) versus CP-induced nephrotoxicity in the same animal model. They attributed these effects to the antioxidant dose, because high doses of some antioxidants do not have a protective effect, and can exacerbate tissue damage.[2,3] Here, I would like to explain the potential mechanism may be related to this difference. The CP-induced nephrotoxicity is a gender dependent; the greater intensity of damage in male than female.[4] Gender differences of CP-induced nephrotoxicity may be related to CP uptake by OCT2; which has been demonstrated to be higher expressed in male than in female rats.[5] Thus, CP uptake was increased by OCT2 overexpression in male rats and associated with increased cellular sensitivity to CP toxicity.[6] A study demonstrated that OCT2 level was significantly reduced in mice after castration.[7] Moreover, a recent study concluded that CP therapy should be avoided when the serum testosterone (TS) level is high because TS in high concentrations (the selected doses: 50 mg/kg and 100 mg/kg) promote CP-induced nephrotoxicity in surgical castrated rats.[8] Furthermore, a recent study showed that the low dose of TS (10 mg/kg) protects kidneys against CP-induced nephrotoxicity in surgical castrated rats.[8] Subsequently, It seems the protective effect of TS on CP-induced nephrotoxicity depend on its dose. In addition, several studies concluded that the consumption of PFE increases significantly TS level in male rats.[9] Finally, I suggest the low dose of PFE (25 mg/kg) increase TS level closed to physiological normal level; however, the high dose of PFE (50 mg/kg) increase TS level in manner leads to increase gene expression of OCT2. Therefore, low dose of PFE showed protective effects; in contrast, the high dose of PFE exacerbate tissue damage resulting from increased CP uptake by OCT2 overexpression in male rats and associated with increased cellular sensitivity to CP toxicity.

Population Pharmacokinetic–Toxicodynamic Modeling and Simulation of Cisplatin-Induced Acute Renal Injury in Rats: Effect of Dosing Rate on Nephrotoxicity

Nephrotoxicity is the major dose-limiting toxicity of cisplatin (CDDP). The aim of this study was to develop a pharmacokinetic (PK)/toxicodynamic (TD) model of CDDP-induced acute renal injury in rats and to simulate nephrotoxicity at various dosing rates. CDDP was administered to rats by a 30-s bolus or a 2-h infusion (1.0, 2.5, 5.0, and 7.5 mg/kg). Unbound CDDP concentrations in plasma and urine were determined up to 2 h after administration in the PK study, and plasma creatinine (Cr) levels were monitored for up to 7 days as an index of nephrotoxicity in the TD study. The PK was linear and was fitted with a traditional 2-compartment model. The TD was nonlinear and differed between dosing rates. The creatinine concentration profiles were fitted with a signal transduction–indirect response model. Population analysis using a nonlinear mixed-effect model was adapted to the developed PK/TD model and was well-validated. Dosing simulations from the developed population PK/TD model indicated that CDDP-induced nephrotoxicity was due to not only Cmax but also the time above the toxic concentration of CDDP. Prolongation of infusion time will not necessarily attenuate acute nephrotoxicity. This study demonstrated the potential utility of PK/TD modeling for preventing nephrotoxicity.

Abstract B23: A phase 1 study in patients with mesothelioma or non small cell lung tumours requiring arginine to assess ADI-PEG 20 with pemetrexed and cisplatin (TRAP study)

Abstract Background: Loss of the metabolic tumor suppressor, argininosuccinate synthetase (ASS1), the rate-limiting enzyme in arginine biosynthesis, sensitizes mesothelioma and lung carcinoma cells to apoptosis following arginine withdrawal. We have reported treatment with the arginine depletor pegylated arginine deiminase (ADI-PEG 20) in ASS1-negative tumor cells potentiates the cytotoxic effect of pemetrexed, accompanied by suppression of de novo pyrimidine synthesis and the pyrimidine salvage pathway (Allen et al, Cancer Res 2014. We have undertaken a phase I study (NCT02029690) of ADI-PEG 20 combined with first-line pemetrexed and cisplatin chemotherapy in patients (pt) with ASS1-deficient mesothelioma or non-squamous non-small cell lung cancer (NSCLC), primary objective was to recommend a dose for future study (RP2D). Methods: Main inclusion criteria: ≥ 18 years, PS ≤ 1, tumour ASS1 loss (≤ 50% ASS expression by IHC) with adequate organ function and written, informed consent. Exclusion criteria: symptomatic CNS metastases, significant concurrent morbidity, therapeutic anticoagulation, history of seizures, or allergy to trial medication(s). A 3+3+3 phase 1 dose escalation design was used with increasing doses of weekly ADI-PEG 20 (18, 27 and 36 mg/m2 IM) in each of three cohorts plus pemetrexed 500 mg/m2 and cisplatin 75 mg/m2 both given every 3 weeks (1 cycle), maximum 18 weeks. ADI-PEG 20 alone was allowed after 18 weeks if there was stable disease or better. Adverse events were graded using CTCAE v4.03 and dose limiting toxicities (DLT) were defined as: Grade 4 neutropenia (> 7 days), febrile neutropenia, Grade 4 anaemia or thrombocytopenia, other clinically significant Grade 3/4 non haematological toxicity that occurred during cycle 1. Radiological disease response was assessed every 6 weeks (modified RECIST for mesothelioma and RECIST 1.1 for NSCLC) and peripheral blood samples were collected to measure plasma arginine and citrulline levels and antibodies to ADI-PEG 20. Results: 42 pt were screened for tumor ASS1 expression and 15 (36%) were ASS1-deficient. Subsequently, 9 pt were eligible for DLT assessment. Demographics - 6 M:3 F, Age range 62 - 77, NSCLC (4): Mesothelioma (5), Prior therapy EGFRi (1 pt), External beam radiotherapy (2 pt) No DLT were observed at any dose level. Grade ≤ 3, AE related to pemetrexed and cisplatin were (5 pt): nausea (5), fatigue (2) and vomiting, peripheral neuropathy, dry mouth, mouth ulcers, dehydration and neutropenia (1 each). No AE were reported related to ADI PEG 20. Mean cycles of treatment: 9 (range 4 - 14) 1 pt was dose reduced after cisplatin toxicity. Arginine was depleted for ≥3 weeks (3-18 weeks in all treated patients. 7/9 pt had partial response (PR) and 2/9 had stable disease (SD) as best response. Conclusions: The combination was well tolerated, the RP2D is 36mg/m2 ADI-PEG 20 weekly with pemetrexed 500 mg/m2 and cisplatin 75 mg/m2 every 3 weeks. Robust clinical activity has been observed with 78% pt having PR as best response on CT scan, as well as PR and SD in2 pt with sarcomatoid mesothelioma. The tolerability and response / disease control rate suggest that this combination may have clinical utility as first line treatment for these malignancies in ASS1-deficient pt. RP2D expansion cohorts are ongoing for pt with pleural mesothelioma or non-squamous NSCLC. Citation Format: Simon Pacey, James F. Spicer, Pui Ying Chan, Mirela Hategan, Dimitra Repana, Jeremy Peter Steele, Peter Schmid, Gary J R Cook, Monica Diaz, Amanda Johnston, Richard Baird, Adelberto Barba, Ramsay Khadeir, Michael Sheaff, Jose Roca, Teresa Szyszko, John Bomalaski, Peter Wojciech Szlosarek. A phase 1 study in patients with mesothelioma or non small cell lung tumours requiring arginine to assess ADI-PEG 20 with pemetrexed and cisplatin (TRAP study). [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr B23.

Platinum antitumor complexes

In the last 50 years the oncology has experienced remarkable changes resulting in transforming malignant germ-cell testicular tumors from highly fatal to nearly uniformly cured neoplasms. This clinical landmark was justly attributed to the identification of cisplatin by Barnett Rosenberg in his experiments dating to 1965. On this 50th anniversary of this discovery, one is reminded of the following key aspects in cancer therapeutics: 1) the life-story of Barnett Rosenberg and his legacy that included organizing nearly quadrennial "platinum" meetings incorporating advances in cancer biology into evolving therapeutic strategies; 2) the search for less toxic analogs of cisplatin leading to the development of carboplatin; 3) clinical research into attenuation of cisplatin toxicities; 4) oxaliplatin and the expansion of the therapeutic spectrum of platinum compounds; and 5) the ongoing multifaceted investigations into the problem of "platinum resistance".

Loss of STAT1 protects hair cells from ototoxicity through modulation of STAT3, c-Jun, Akt, and autophagy factors.

Hair cell damage is a side effect of cisplatin and aminoglycoside use. The inhibition or attenuation of this process is a target of many investigations. There is growing evidence that STAT1 deficiency decreases cisplatin-mediated ototoxicity; however, the role of STAT function and the molecules that act in gentamicin-mediated toxicity have not been fully elucidated. We used mice lacking STAT1 to investigate the effect of STAT1 ablation in cultured organs treated with cisplatin and gentamicin. Here we show that ablation of STAT1 decreased cisplatin toxicity and attenuated gentamicin-mediated hair cell damage. More TUNEL-positive hair cells were observed in explants of wild-type mice than that of STAT1−/− mice. Although cisplatin increased serine phosphorylation of STAT1 in wild-type mice and diminished STAT3 expression in wild-type and STAT1−/− mice, gentamicin increased tyrosine phosphorylation of STAT3 in STAT1−/− mice. The early inflammatory response was manifested in the upregulation of TNF-α and IL-6 in cisplatin-treated explants of wild-type and STAT1−/− mice. Expression of the anti-inflammatory cytokine IL-10 was altered in cisplatin-treated explants, upregulated in wild-type explants, and downregulated in STAT1−/− explants. Cisplatin and gentamicin triggered the activation of c-Jun. Activation of Akt was observed in gentamicin-treated explants from STAT1−/− mice. Increased levels of the autophagy proteins Beclin-1 and LC3-II were observed in STAT1−/− explants. These data suggest that STAT1 is a central player in mediating ototoxicity. Gentamicin and cisplatin activate different downstream factors to trigger ototoxicity. Although cisplatin and gentamicin triggered inflammation and activated apoptotic factors, the absence of STAT1 allowed the cells to overcome the effects of these drugs.

An RNA interference screen identifies new avenues for nephroprotection.

Acute kidney injury is a major public health problem, which is commonly caused by renal ischemia and is associated with a high risk of mortality and long-term disability. Efforts to develop a treatment for this condition have met with very limited success. We used an RNA interference screen to identify genes (BCL2L14, BLOC1S2, C2ORF42, CPT1A, FBP1, GCNT3, RHOB, SCIN, TACR1, and TNFAIP6) whose suppression improves survival of kidney epithelial cells in in vitro models of oxygen and glucose deprivation. Some of the genes also modulate the toxicity of cisplatin, an anticancer agent whose use is currently limited by nephrotoxicity. Furthermore, pharmacological inhibition of TACR1 product NK1R was protective in a model of mouse renal ischemia, attesting to the in vivo relevance of our findings. These data shed new light on the mechanisms of stress response in mammalian cells, and open new avenues to reduce the morbidity and mortality associated with renal injury.

A comparison of the toxicity and tolerability of two intraperitoneal chemotherapy regimens for advanced-stage epithelial ovarian cancer

ObjectivesRandomized controlled trials (RCTs) in optimally cytoreduced epithelial ovarian cancer (EOC) patients have demonstrated an impressive survival benefit of intraperitoneal (IP) platinum over intravenous (IV), but its use has been limited by significant toxicity from cisplatin. The aim of this study was to compare the toxicity and tolerability of IP cisplatin to IP carboplatin in women with optimally cytoreduced EOC. MethodsRetrospective analysis of 141 women with EOC who underwent optimal surgical cytoreduction followed by IV paclitaxel and IP cisplatin or IP carboplatin was performed. Toxicities of the two treatment regimens were compared. As a secondary outcome, overall survival (OS) and progression-free survival (PFS) probabilities were obtained using the Kaplan–Meier estimate; the log-rank test was used to compare survival curves. ResultsOf the 141 patients, 77 (54.6%) received IP cisplatin and 64 (45.4%) received IP carboplatin. Eighty-six percent received at least 4cycles of IP chemotherapy. IP cisplatin was associated with significantly more grade 3 nausea and vomiting (10.4% vs 1.6%, p=0.033), grade 3 neuropathy (7.8% vs 0%, p=0.013) and grade 2–3 neutropenia (22.1% vs 9.4%, p=0.042). No difference in PFS (p=0.602) or OS (p=0.107) was found between the groups. ConclusionIP chemotherapy had a high completion rate in both groups of patients. IP carboplatin required a less resource intense protocol and was tolerated better than IP cisplatin with less gastrointestinal, neurologic and hematologic toxicities.

Ancient Chinese Formula Qiong-Yu-Gao Protects Against Cisplatin-Induced Nephrotoxicity Without Reducing Anti-tumor Activity.

Cisplatin is a highly effective anti-cancer chemotherapeutic agent; however, its clinical use is severely limited by serious side effects, of which nephrotoxicity is the most important. In this study, we investigated whether Qiong-Yu-Gao (QYG), a popular traditional Chinese medicinal formula described 840 years ago, exhibits protective effects against cisplatin-induced renal toxicity. Using a mouse model of cisplatin-induced renal dysfunction, we observed that pretreatment with QYG attenuated cisplatin-induced elevations in blood urea nitrogen and creatinine levels, ameliorated renal tubular lesions, reduced apoptosis, and accelerated tubular cell regeneration. Cisplatin-mediated elevations in tumor necrosis factor alpha (TNF-α) mRNA, interleukin-1 beta (IL-1β) mRNA, and cyclooxygenase-2 (COX-2) protein in the kidney were also significantly suppressed by QYG treatment. Furthermore, QYG reduced platinum accumulation in the kidney by decreasing the expression of copper transporter 1 and organic cation transporter 2. An in vivo study using implanted Lewis lung cancer cells revealed that concurrent administration of QYG and cisplatin did not alter the anti-tumor activity of cisplatin. Our findings suggest that the traditional Chinese medicinal formula QYG inhibits cisplatin toxicity by several mechanisms that act simultaneously, without compromising its therapeutic efficacy. Therefore, QYG may be useful in the clinic as a protective agent to prevent cisplatin-induced nephrotoxicity.

Molecular mechanisms of cisplatin cytotoxicity in acute promyelocytic leukemia cells.

Cis-diamminedichloroplatinum (II) (cisplatin) is a widely used anti-tumor drug for the treatment of a broad range of human malignancies with successful therapeutic outcomes for head and neck, ovarian, and testicular cancers. It has been found to inhibit cell cycle progression and to induce oxidative stress and apoptosis in acute promyelocytic leukemia (APL) cells. However, its molecular mechanisms of cytotoxic action are poorly understood. We hypothesized that cisplatin induces cytotoxicity through DNA adduct formation, oxidative stress, transcriptional factors (p53 and AP-1), cell cycle regulation, stress signaling and apoptosis in APL cells. We used the APL cell line as a model, and applied a variety of molecular tools to elucidate the cytotoxic mode of action of cisplatin. We found that cisplatin inhibited cell proliferation by a cytotoxicity, characterized by DNA damage and modulation of oxidative stress. Cisplatin also activated p53 and phosphorylated activator protein (AP-1) component, c-Jun at serine (63, 73) residue simultaneously leading to cell cycle arrest through stimulation of p21 and down regulation of cyclins and cyclin dependent kinases in APL cell lines. It strongly activated the intrinsic pathway of apoptosis through alteration of the mitochondrial membrane potential, release of cytochrome C, and up-regulation of caspase 3 activity. It also down regulated the p38MAPK pathway. Overall, this study highlights the molecular mechanisms that underline cisplatin toxicity to APL cells, and provides insights into selection of novel targets and/or design of therapeutic agents to treat APL.

Inhibition of Autophagy Potentiated the Antitumor Effect of Nedaplatin in Cisplatin-Resistant Nasopharyngeal Carcinoma Cells.

Nedaplatin, a cisplatin analog, was developed to reduce the toxicity of cisplatin, whereas it can be cross-resistant with cisplatin in some circumstances. This study aimed to investigate the role of autophagy in nedaplatin induced cell death in cisplatin-resistant nasopharyngeal carcinoma cells. Here, we showed that HNE1/DDP and CNE2/DDP cells were resistant to nedaplatin-induced cell death with reduced apoptotic activity. Nedaplatin treatment resulted in autophagosome accumulation and increased expression of LC3-II, indicating the induction of autophagy by nedaplatin in HNE1/DDP and CNE2/DDP cells. Inhibition of autophagy by Bafilomycin A1 (Baf A1) and 3-Methyladenine (3-MA) remarkably enhanced the antitumor efficacy of nedaplatin in HNE1/DDP and CNE2/DDP cells, suggesting that the resistance to nedaplatin-induced cell death was caused by enhanced autophagy in nedaplatin-resistant NPC cells. Additionally, Baf A1 enhanced reactive oxygen species (ROS) generation and apoptosis induced by nedaplatin in HNE1/DDP cells. Mechanistically, nedaplatin treatment caused activation of ERK1/2 and suppression of Akt/mTOR signaling pathways. While inhibition of ERK1/2 by MEK1/2 inhibitor, U0126, could reduce the expression of LC3-II in nedaplatin-resistant NPC cells. Furthermore, suppression of ROS could inhibit nedaplatin-induced ERK activation in HNE1/DDP cells, indicating that ROS and ERK were involved in nedaplatin-induced autophagy. Together, these findings suggested that autophagy played a cytoprotective role in nedaplatin-induced cytotoxicity of HNE1/DDP and CNE2/DDP cells. Furthermore, our results highlighted a potential approach to restore the sensitivity of cisplatin-resistant nasopharyngeal cancer cells to nedaplatin in combination with autophagy inhibitors.

Abstract POSTER-THER-1425: Novel small molecules overcoming platinum drug resistance in ovarian cancer cells

Abstract After stage, platinum drug resistance is the single most important factor in determining prognosis in ovarian cancer. Overcoming platinum drug resistance by pharmacological manipulations represents a major challenge in the current clinical practice for the management of ovarian cancer. We discovered a novel drug combination approach using platinum agents with mdivi-1 (mitochondrial division inhibitor 1) that is able to synergistically induce rapid apoptosis in platinum-resistant ovarian cancer cells, including established cisplatin-resistant ovarian cancer cell lines as well as primary cancer cells derived from ovarian cancer patients. We also identified that the synergism between cisplatin and mdivi-1 is not dependent on Drp1 (a mitochondrial fission protein and the reported target of mdivi-1), as mdivi-1 enhances cisplatin toxicity in Drp1 knockout mouse embryonic fibroblast (MEF) cells. In order to improve the compound properties of mdivi-1, we performed a structure activity relationship (SAR) study of mdivi-1 and assembled and screened a small library of structurally related compounds. We were able to identify more potent novel small molecules that synergize with platinum agents. We found that short-term exposure of cells to the combination of cisplatin and those novel compounds is sufficient to reduce cell viability, while cisplatin alone treatment only slightly inhibited cell proliferation in cisplatin-resistant ovarian cancer cells. We further identified that mdivi-1 and its structurally related novel small molecules, when combined with cisplatin, induce a synergistic increase of replication stress and DNA damage, causing upregulation of a pro-apoptotic Bcl-2 family protein Noxa. These small molecules also repress mitochondrial respiration and the combination with cisplatin triggers substantial mitochondrial dysfunction including mitochondrial uncoupling. DNA replication stress and mitochondrial dysfunction converge on the induction of mitochondrial outer membrane permeabilization (MOMP) proceeding robust mitochondrial apoptotic signaling, bypassing a Bax/Bak-dependent mechanism. Since apoptosis induced by cisplatin alone relies on Bax/Bak-dependent MOMP, and inefficient activation of Bax/Bak-dependent MOMP is often associated with cisplatin resistance, the combination of cisplatin and mdivi-1 family compounds represents a novel strategy in overcoming platinum resistance. We thus present a novel platinum-based combination approach in the treatment of platinum resistant ovarian cancer. Citation Format: Wei Qian, Jingnan Wang, Robert Edwards, Peter Wipf, Bennett Van Houten. Novel small molecules overcoming platinum drug resistance in ovarian cancer cells [abstract]. In: Proceedings of the 10th Biennial Ovarian Cancer Research Symposium; Sep 8-9, 2014; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(16 Suppl):Abstract nr POSTER-THER-1425.

Simvastatin protects Sertoli cells against cisplatin cytotoxicity through enhanced gap junction intercellular communication.

Cisplatin, an important chemotherapeutic agent against testicular germ cell cancer, induces testicular toxicity on Leydig and Sertoli cells, leading to serious side-effects such as azoospermia and infertility. In a previous study, it was found that simvastatin enhanced the sensitivity of Leydig tumor cells to chemotherapeutic toxicity through the enhancement of gap junction functions. In the present study, the effect of simvastatin on the sensitivity of normal Sertoli cells to cisplatin and the role of gap junctions in such effects was investigated. The results showed that, simvastatin attenuated cisplatin toxicity only when cells exhibited high-density culture where gap junctional formation was possible. When gap junction function was decreased by the gap junction inhibitor or by siRNA targeting connexin 43, the protective effect of simvastatin to cisplatin toxicity was substantially attenuated. Simvastatin also enhanced gap junction functions between Sertoli cells. This effect was mediated by the reduction of PKC-mediated connexin phosphorylation, thereby increasing connexin 43 membrane localization. Thus, simvastatin-induced enhancement of gap junction‑mediated intercellular communication attenuated cisplatin toxicity on Sertoli cells. This result indicated that enhancement of gap junction function by simvastatin may have bilateral beneficial effects on cisplatin‑based chemotherapy, enhancing cisplatin killing on cancer while ameliorating the reproduction toxicity.

The protective effect of pomegranate extract against cisplatin toxicity in rat liver and kidney tissue

Objectives: The purpose of this study was to perform a histopathological investigation, at the light microscopy level, of the protective effects of pomegranate extract in cisplatin-induced liver and kidney damage in rats. Material and methods: Twenty-eight adult male Wistar albino rats were randomly divided into four groups of seven animals: Group 1: Control; Group 2: Treated for 10 consecutive days by gavage with pomegranate juice (2 ml/kg/day); Group 3: Injected intraperitoneally with cisplatin (8 mg/kg body weight, single dose) onset of the day 5, and Group 4: Treated by gavage with pomegranate juice 10 days before and after a single injection of cisplatin onset of the day 5. After 10 days, the animals were sacrificed and their kidneys and liver tissue samples were removed from each animal after experimental procedures. Cisplatin-induced renal and hepatic toxicity and the effect of pomegranate juice were evaluated by histopatological examinations. Results: In the kidney tissue, pomegranate juice significantly ameliorated cisplatin-induced structural alterations when compared with the cisplatin alone group. But in the liver tissue, although pomegranate juice attenuated the cisplatin-induced toxicity only in two rats, significant improvement was not observed. Conclusion: In conclusion, these results demonstrate that the anti-oxidant pomegranate juice might have a protective effect against cisplatin-induced toxicity in rat kidney, but not in liver. Pomegranate juice could be beneficial as a dietary supplement in patients receiving chemotherapy medications.