Different cell cycle modulation following treatment of human ovarian carcinoma cells with a new platinum(IV) complex vs cisplatin

Emerging platinum(IV) prodrug nanotherapeutics: A new epoch for platinum-based cancer therapy

Owing to the unique DNA damaging cytotoxicity, platinum (Pt)-based chemotherapy has long been the first-line choice for clinical oncology. Unfortunately, Pt drugs are restricted by the severe dose-dependent toxicity and drug resistance. Correspondingly, Pt(IV) prodrugs are developed with the aim to improve the antitumor performance of Pt drugs. However, as "free" molecules, Pt(IV) prodrugs are still subject to unsatisfactory in vivo destiny and antitumor efficacy. Recently, Pt(IV) prodrug nanotherapeutics, inheriting both the merits of Pt(IV) prodrugs and nanotherapeutics, have emerged and demonstrated the promise to address the underexploited dilemma of Pt-based cancer therapy. Herein, we summarize the latest fronts of emerging Pt(IV) prodrug nanotherapeutics. First, the basic outlines of Pt(IV) prodrug nanotherapeutics are overviewed. Afterwards, how versatile Pt(IV) prodrug nanotherapeutics overcome the multiple biological barriers of antitumor drug delivery is introduced in detail. Moreover, advanced combination therapies based on multimodal Pt(IV) prodrug nanotherapeutics are discussed with special emphasis on the synergistic mechanisms. Finally, prospects and challenges of Pt(IV) prodrug nanotherapeutics for future clinical translation are spotlighted.

Ubiquitin-specific peptidase 39 regulates the process of proliferation and migration of human ovarian cancer via p53/p21 pathway and EMT

Ovarian cancer is one of the most lethal gynecological cancers; owning to its late detection and chemoresistance, understanding the pathogenesis of this malignant tumor is much critical. Previous studies have reported that ubiquitin-specific peptidase 39 (USP39) is generally overexpressed in a variety of cancers, including hepatocellular carcinoma, gastric cancer and so forth. Furthermore, USP39 is proved to be associated with the proliferation of malignant tumors. However, the function and mechanism of USP39 in ovarian cancer have not been elucidated. In the present study, we observed that USP39 was frequently overexpressed in human ovarian cancer and was highly correlated with TNM stage. Suppression of USP39 markedly inhibited the growth and migration of ovarian cancer cell lines HO-8910 and SKOV3 and induced cell cycle G2/M arrest. Moreover, knockdown of USP39 inhibited ovarian tumor growth in a xenograft model. In addition, our findings indicated that cell cycle arrest induced by USP39 knockdown might be involved in p53/p21 signaling pathway. Furthermore, we found that the depletion of USP39 inhibited the migration of ovarian cancer cells via blocking epithelial-mesenchymal transition. Taken together, these results suggest that USP39 may play vital roles in the genesis and progression and may serve as a potential biomarker for diagnosis and therapeutic target of ovarian cancer.

Review on Pharmacology of Cisplatin: Clinical Use, Toxicity and Mechanism of Resistance of Cisplatin

Cisplatin is a chemotherapeutic drug that has been used in the treatment of various types of human cancers such as ovarian, lung, head and neck, testicular and bladder. Cisplatin has demonstrated efficacy against various types of cancers such as germ cell tumors, sarcomas, carcinomas as well as lymphomas. The current study presents a pharmacological review on the drug including its mechanism of action, resistance mechanism, and toxicity as well as its clinical applications. The mechanism of action of cisplatin has been associated with ability to crosslink with the urine bases on the DNA to form DNA adducts, preventing repair of the DNA leading to DNA damage and subsequently induces apoptosis within cancer cells. However, the drug exhibits certain level of resistance including increased repair of the damaged DNA, reduction in the accumulation of the drug intracellular and cytosolic inactivation of cisplatin. The drug is also characterized by various toxic side effects including nausea, nephrotoxicity, Cardiotoxicity, hepatotoxicity and neurotoxicity. Due various side effects as well as drug resistance, other anti-cancer drugs that contain platinum such as carboplatin and oxaliplatin among others have been used in combination with cisplatin in chemotherapeutic treatment of cancer. Strong evidence from research has demonstrated higher efficacy of combination of chemotherapies of cisplatin together with other drugs in overcoming drug resistance and in reducing toxic effects as well. Future studies that explore combinational techniques that target various mechanisms such as reduction in the uptake of cisplatin as well as inflammation could enhance efficacy of cisplatin.

Salidroside, a Chemopreventive Glycoside, Diminishes Cytotoxic Effect of Cisplatin in Vitro

Natural products represent the source or the inspiration for the majority of the active ingredients of medicines because of their structural diversity and a wide range of biological effects. Our aims in this study were (i) to synthesize enzymatically salidroside (SAL), the most effective phenylethanoid glycoside in Rhodiola species; (ii) to examine its antioxidant capacity using cell-free assays (reducing power, DPPH radicals scavenging and Fe²⁺ -chelating assays); (iii) to assess its DNA-protective potential on plasmid DNA (DNA topology assay) and in HepG2 cells (comet assay) damaged by Fe²⁺ ions and hydrogen peroxide, respectively; and (iv) to investigate the effects of SAL, cisplatin (CDDP) and combined treatments of SAL + CDDP on cell viability (MTT test), level of DNA damage (comet assay), proliferation, cell cycle (flow cytometry) and the expression of signalling molecules associated with cell growth and apoptotic pathways (Western immunoblotting). We found out that SAL manifested low antioxidant and DNA-protective capacity in all assays used. In both parental A2780 and CDDP-resistant A2780/CP human ovarian carcinoma cells, SAL itself exerted in fact no impact on the viability, while in combination with CDDP it showed antagonistic effect supporting the chemopreventive activity on the CDDP-induced cell damage. These results were confirmed by the partial reversal of the cell cycle alterations and the DNA damage level, as well as with partial restoration of cell survival/signalling pathways, when the expression of these molecules partially returned to their proper levels.

Cisplatin plus sodium arsenite and hyperthermia induces pseudo-G1 associated apoptotic cell death in ovarian cancer cells

Cisplatin is effective against solid tumors including ovarian cancer. However, inherent or acquired cisplatin resistance limits clinical success. We recently demonstrated that a combination of sodium arsenite (NaAsO2) and hyperthermia sensitizes p53-expressing ovarian cancer cells to cisplatin by modulating DNA repair pathway and enhancing platinum accumulation. However, it is not understood how this combination therapy modulates cell cycle following platinum-DNA damage. The goal of the present study was to determine if NaAsO2 and hyperthermia alter cisplatin-induced G2 arrest and cause mitotic arrest and mitotic catastrophe. Human epithelial ovarian cancer cells (A2780 and A2780/CP70) were treated with cisplatin ± 20 μM NaAsO2 at 37 or 39°C for 1 h. Cisplatin ± NaAsO2 at 37 or 39°C caused cells to accumulate in G2/M compartment at 36 h after treatment. Western blot analysis of cyclin A and cyclin B suggested that combined NaAsO2, hyperthermia, and cisplatin induced mitotic arrest. However, we observed < 3% mitotic index and phosphorylation of histone H3 on serine 10 was undetectable. These results did not confirm mitotic arrest. BUBR1 (BUB1B) also was not phosphorylated, suggesting disrupted mitotic checkpoint. Postmitotic cells accumulated in pseudo-G1 as demonstrated by cyclin E stabilization, CDKN1A induction, and hypophosphorylation of retinoblastoma protein. These cells also were positive for Annexin V binding indicating they were apoptotic. In summary, cisplatin plus NaAsO2 and hyperthermia induced pseudo-G1 associated apoptosis in ovarian cancer cells.

Higher anti-tumour efficacy of platinum(IV) complex LA-12 is associated with its ability to bypass M-phase entry block induced in oxaliplatin-treated human colon cancer cells

OBJECTIVES

Therapeutic potential of conventionally used platinum-based drugs in treatment of colorectal tumours has been limited due to high incidence of tumour resistance to them and to their severe side effects. This evokes a search for more suitable anti-cancer drugs. We have compared ability of oxaliplatin and a novel platinum(IV) complex, LA-12, to modulate the cell cycle and induce apoptosis in human colon adenocarcinoma HCT116 wt and p53/p21 null cells, and have investigated molecular mechanisms involved.

MATERIALS AND METHODS

Cell cycle-related changes were analysed by flow cytometry (bromodeoxyuridine/propidium iodide staining, histone H3 phosphorylation). Apoptosis was detected using flow cytometry (assays monitoring caspase activity) and fluorescence microscopy (nuclear morphology). Changes in levels of genes/proteins involved in cell cycle and apoptosis regulation were examined by RT-PCR and western blotting.

RESULTS

Our results highlight the outstanding ability of LA-12 to induce effective elimination of colon cancer cells independently of p53/p21, and in significantly lower doses compared to oxaliplatin. While oxaliplatin induced p53- and p21-dependent G2 -phase arrest associated with downregulation of cyclin B1 and Cdk1, LA-12 allowed cells to enter M-phase of the cell cycle regardless of p53/p21 status.

CONCLUSIONS

Higher malignant cell toxicity and ability to bypass cell cycle arrest important for the cell damage repair suggest LA-12 to be a more effective candidate for elimination of colon tumours from a variety of genetic backgrounds, compared with oxaliplatin.

Bulky N(,N)-(di)alkylethane-1,2-diamineplatinum(II) compounds as precursors for generating unsymmetrically substituted platinum(IV) complexes

Investigations of the influence of bulky groups in the equatorial ligand sphere of platinum(IV) compounds on the complexes' stability and reaction pattern were performed. Four dihydroxidoplatinum(IV) complexes were reacted with anhydrides, cinnamoyl chloride, and n-propyl isocyanate and yielded the symmetric dicarboxylated products or, if steric hindrance was observed, unsymmetrically substituted monocarboxylated analogues. With the aim of raising the steric demand, the following ligands were chosen: N-cyclohexylethane-1,2-diamine, N,N-dimethylethane-1,2-diamine, N,N-diethylethane-1,2-diamine, and N,N-diisopropylethane-1,2-diamine. All of the novel complexes were characterized by electrospray ionization mass spectrometry (ESI-MS), one- and two-dimensional NMR spectroscopy, elemental analysis, and reversed-phase HPLC; complexes B3, C3, C6, and D4 were also analyzed by X-ray diffraction. Additionally, the cytotoxicities of 10 compounds toward the cisplatin-sensitive cell line CH1 and the intrinsically cisplatin-resistant cell lines A549 and SW480 were investigated, and IC50 values down to the nanomolar range were found. To aid in the interpretation of structure-activity relationships, log k(w) values as a measure for the lipophilicity were determined for all of the new complexes, and the rates of reduction of C1, C3, and C4 relative to satraplatin were determined by means of NMR spectroscopy and ESI-MS.

The new platinum-based anticancer agent LA-12 induces retinol binding protein 4 in vivo

BACKGROUND

The initial pharmacokinetic study of a new anticancer agent (OC-6-43)-bis(acetato)(1-adamantylamine)amminedichloroplatinum (IV) (LA-12) was complemented by proteomic screening of rat plasma. The objective of the study was to identify new LA-12 target proteins that serve as markers of LA-12 treatment, response and therapy monitoring.

METHODS

Proteomic profiles were measured by surface-enhanced laser desorption-ionization time-of-flight mass spectrometry (SELDI-TOF MS) in 72 samples of rat plasma randomized according to LA-12 dose and time from administration. Correlation of 92 peak clusters with platinum concentration was evaluated using Spearman correlation analysis.

RESULTS

We identified Retinol-binding protein 4 (RBP4) whose level correlated with LA-12 level in treated rats. Similar results were observed in randomly selected patients involved in Phase I clinical trials.

CONCLUSIONS

RBP4 induction is in agreement with known RBP4 regulation by amantadine and cisplatin. Since retinol metabolism is disrupted in many cancers and inversely associates with malignancy, these data identify a potential novel mechanism for the action of LA-12 and other similar anti-cancer drugs.

The new platinum(IV) derivative LA-12 shows stronger inhibitory effect on Hsp90 function compared to cisplatin

Background

Cisplatin and its derivatives are commonly used anti-cancer drugs. However, cisplatin has clinical limitations including serious side effects and frequent emergence of intrinsic or acquired resistance. Thus, the novel platinum(IV) complex LA-12 represents a promising treatment modality, which shows increased intracellular penetration resulting in improved cytotoxicity in various cancer cell lines, including cisplatin resistant cells.

Results

LA-12 disrupts cellular proliferation regardless of the p53 status in the cells, however the potency of the drug is greatly enhanced by the presence of a functional p53, indicating several mechanisms of action. Similarly to cisplatin, an interaction of LA-12 with molecular chaperone Hsp90 was proposed. Binding of LA-12 to Hsp90 was demonstrated by Hsp90 immunoprecipitation followed by platinum measurement using atomic absorption spectrometry (AAS). An inhibitory effect of LA-12 on Hsp90 chaperoning function was shown by decrease of Hsp90-assisted wild-type p53 binding to p21^WAF1 promoter sequence in vitro and by accelerated ubiqutination and degradation of primarily unfolded mutant p53 proteins in cells exposed to LA-12.

Conclusions

To generalize our findings, LA-12 induced degradation of other Hsp90 client proteins such as Cyclin D1 and estrogen receptor was shown and proved as more efficient in comparison with cisplatin. This newly characterised molecular mechanism of action opens opportunities to design new cancer treatment strategy profitable from unique LA-12 properties, which combine DNA damaging and Hsp90 inhibitory effects.

The effect of cellular environment and p53 status on the mode of action of the platinum derivative LA-12

In this study, we characterized the effects of LA-12 on tumor cell lines possessing wild type p53 and on p53-deficient/mutant cell lines and the results were compared to those obtained using cisplatin. We have determined changes of p53 levels, of its transcriptional activity, of its posttranscriptional modifications and the effect of the treatment on the cell cycle, on the induction of apoptosis and on gene expression. LA-12 induces weak accumulation of both transcriptionally active p53 tumor suppressor and of p21(WAF1/CIP1) protein. LA-12 and cisplatin also significantly differ in their effects on apoptosis and cell cycle and on gene expression spectra in studied cell lines. LA-12 induces higher apoptosis levels in comparison with those induced by cisplatin, especially in p53-deficient H1299 cells and in MCF-7DD cells with transcriptionally inactive p53. We suggest that LA-12-mediated apoptosis is not fully dependent on p53. This confirms the therapeutic potential of LA-12 as a more potent cytostatic agent for both tumor cells expressing wild type p53 and for p53-deficient or mutant cells.

Regulation of ovarian cancer cell viability and sensitivity to cisplatin by progesterone receptor membrane component-1

CONTEXT

Progesterone (P4) influences ovarian cancer cells by an unknown mechanism.

OBJECTIVE

The objective was to determine whether P4 acts through progesterone receptor membrane component-1 (PGRMC1) in ovarian cancers.

DESIGN, SETTING AND PATIENTS

Archival tissue and cDNA provided by OriGene were used for expression studies. In vitro experiments were conducted with Ovcar-3 cells.

MAIN OUTCOME MEASURES

PCR, Western blot, and immunohistochemistry were used to measure expression of PGRMC1 and nuclear progesterone receptor (PGR). PGRMC1's role in regulating the viability of ovarian cancers was assessed by overexpressing PGRMC1, depleting PGRMC1 using small interfering RNA, and attenuating PGRMC1's action with a blocking antibody. Apoptosis was determined by 4',6'-diamino-2-phenylindole staining.

RESULTS

PGRMC1 mRNA increased and PGR mRNA decreased in advanced stages of ovarian cancer. Unlike PGR, PGRMC1 was expressed in virtually every cancer cell within the tumor. A similar relationship between PGRMC1 and PGR was observed in Ovcar-3 cells. In these cells P4 suppressed apoptosis induced by either serum withdrawal or cisplatin (CDDP). Moreover, in the presence of P4, the following occurs: 1) overexpression of PGRMC1 reduces the effectiveness of CDDP, 2) depletion of PGRMC1 with small interfering RNA enhances the effects of CDDP, and 3) PGRMC1 antibody treatment increases the apoptotic response to CDDP.

CONCLUSIONS

These findings indicate that PGRMC1 plays an important role in promoting ovarian cancer cell viability and that attenuating PGRMC1's action makes the ovarian cancer cells more sensitive to CDDP. These data suggest that targeted depletion of PGRMC1 could be useful as an adjunct to CDDP therapy.