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.

• MeSH
• Adenocarcinoma drug therapy   genetics   MeSH
• Amantadine analogs & derivatives   pharmacology   MeSH
• Apoptosis drug effects   genetics   MeSH
• Cell Division drug effects   genetics   MeSH
• Cyclin B1 genetics   MeSH
• HCT116 Cells MeSH
• Cyclin-Dependent Kinase Inhibitor p21 genetics   MeSH
• Humans MeSH
• Mitosis drug effects   genetics   MeSH
• Cell Line, Tumor MeSH
• Tumor Suppressor Protein p53 genetics   MeSH
• Colonic Neoplasms drug therapy   genetics   MeSH
• Organoplatinum Compounds pharmacology   MeSH
• Oxaliplatin MeSH
• Cell Proliferation drug effects   MeSH
• Antineoplastic Agents pharmacology   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Amantadine MeSH
• bis(acetato)(1-adamantylamine)amminedichloroplatinum(IV) MeSH Browser
• CDKN1A protein, human MeSH Browser
• Cyclin B1 MeSH
• Cyclin-Dependent Kinase Inhibitor p21 MeSH
• Tumor Suppressor Protein p53 MeSH
• Organoplatinum Compounds MeSH
• Oxaliplatin MeSH
• Antineoplastic Agents MeSH

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.

• Publication type
• Journal Article MeSH

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.

• MeSH
• Amantadine analogs & derivatives   pharmacology   MeSH
• Apoptosis drug effects   MeSH
• Cell Cycle drug effects   MeSH
• Cisplatin pharmacology   MeSH
• Genes, p53 MeSH
• Cyclin-Dependent Kinase Inhibitor p21 metabolism   MeSH
• Humans MeSH
• Mutation MeSH
• Cell Line, Tumor MeSH
• Tumor Suppressor Protein p53 genetics   metabolism   MeSH
• Organoplatinum Compounds pharmacology   MeSH
• Apoptosis Regulatory Proteins metabolism   MeSH
• Antineoplastic Agents pharmacology   MeSH
• Gene Expression Regulation, Neoplastic drug effects   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Amantadine MeSH
• bis(acetato)(1-adamantylamine)amminedichloroplatinum(IV) MeSH Browser
• CDKN1A protein, human MeSH Browser
• Cisplatin MeSH
• Cyclin-Dependent Kinase Inhibitor p21 MeSH
• Tumor Suppressor Protein p53 MeSH
• Organoplatinum Compounds MeSH
• Apoptosis Regulatory Proteins MeSH
• Antineoplastic Agents MeSH

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 p21WAF1 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.

• MeSH
• Amantadine analogs & derivatives   pharmacology   MeSH
• Cisplatin pharmacology   MeSH
• Immunoprecipitation MeSH
• Cyclin-Dependent Kinase Inhibitor p21 drug effects   metabolism   MeSH
• Humans MeSH
• Cell Line, Tumor MeSH
• Tumor Suppressor Protein p53 drug effects   metabolism   MeSH
• Organoplatinum Compounds pharmacology   MeSH
• HSP90 Heat-Shock Proteins drug effects   metabolism   MeSH
• Antineoplastic Agents pharmacology   MeSH
• Spectrophotometry, Atomic MeSH
• Blotting, Western MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Amantadine MeSH
• bis(acetato)(1-adamantylamine)amminedichloroplatinum(IV) MeSH Browser
• CDKN1A protein, human MeSH Browser
• Cisplatin MeSH
• Cyclin-Dependent Kinase Inhibitor p21 MeSH
• Tumor Suppressor Protein p53 MeSH
• Organoplatinum Compounds MeSH
• HSP90 Heat-Shock Proteins MeSH
• Antineoplastic Agents MeSH