Cellular Uptake, DNA Binding and Apoptosis Induction of Cytotoxic Trans-[PtCl(2)(N,N-dimethylamine)(Isopropylamine)] in A2780cisR Ovarian Tumor Cells.

Trans-[PtCl(2)(N,N-dimethylamine)(isopropylamine)] is a novel trans-platinum compound that shows cytotoxic activity in several cisplatin resistant cell lines. The aim of this paper was to analyse, by means of molecular cell biology techniques and total reflection X-ray fluorescence (TXRF), the cytotoxic activity, the induction of apoptosis, the cellular uptake and the DNA binding of trans-[PtCl(2)(N,N-dimethylamine)(isopropylamine)] in the cisplatin resistant cell line A2780cisR. The results show that this drug is more cytotoxic and induces a higher amount of apoptotic cells than cisplatin in A2780cisR cells. However, the intracellular accumulation and extent of binding to DNA of trans-[PtCl(2)(N,N-dimethylamine)( isopropylamine)] is lower than that of cis-DDP. Moreover, trans-[PtCl(2)(N,N-dimethylamine)(isopropylaminae)] is partially inactivated by intracellular levels of glulathione. The result suggest that circumvention of ciplatin resistance by trans-[PtCl(2)(N,N-dimethylamine)(isopropylamine)] in A2780cisR cells might be related with the ability of this drug to induce apoptosis.

X-Ray structure of cytotoxic trans-[PtCl(2)(dimethylamine)(isopropylamine)]: interstrand cross-link efficiency, DNA sequence specificity, and inhibition of the B-Z transition.

We report here the X-ray structure of cytotoxic trans-¿PtCl(2)(dimethylamine)(isopropylamine). This trans-platinum compound crystallizes in the monoclinic system, with Z = 8, in the spatial group C2/c with unit cell parameters a = 19.862(17) A, b = 6. 581(3) A, c = 18.563(3) A, alpha = 90 degrees, beta = 119.16(3) degrees, gamma = 90 degrees, V = 2119(2) A(3), rho = 2.321 Mg/m(3), R = 0.0505, and R(w) = 0.1166 on the basis of 2339 independent reflections. To our knowledge this is the first report of the crystal structure of a biologically active trans-platinum compound containing different aliphatic amines. The DNA binding mode of trans-¿PtCl(2)(dimethylamine)(isopropylamine) may be a consequence of the spatial disposition of the dimethylamine and isopropylamine ligands around the trans-Pt(II) center. We have found that trans-¿PtCl(2)(dimethylamine)(isopropylamine) readily forms DNA interstrand cross-links. In addition, the compound shows binding affinity toward alternating purine-pyrimidine sequences and inhibits the B-Z transition. These particular DNA binding properties might be related to the capacity of trans-¿PtCl(2)(dimethylamine)(isopropylamine) for inducing some selective killing in a H-ras overexpresssing cell line.

Preparation and characterization of novel trans-[PtCl(2)(amine)(isopropylamine)] compounds: cytotoxic activity and apoptosis induction in ras-transformed cells.

The synthesis and chemical characterization of three new transplatinum complexes of structural formula trans-[PtCl(2)(amine)(isopropylamine)] (amine = n,n-dimethylamine, propylamine, and butylamine), 1-3, are described. Cytotoxicity tests in tumor cell lines sensitive to cis-DDP (Jurkat, Hela, and Vero) and also in tumor cell lines overexpressing ras oncogenes and resistant to cis-DDP (HL-60 and Pam 212-ras) show that complexes 1 and 3 have higher cytotoxic activity than cisplatin. Moreover, these two trans-Pt(II) complexes kill Pam 212-ras cells through apoptosis induction. These results suggest that trans-PtCl(2) complexes with asymmetric aliphatic amines may be considered a new class of biologically active trans-platinum drugs.

Synthesis and characterization of Pd(II) and Pt(II) complexes of p-isopropylbenzaldehyde N-protected thiosemicarbazones. Cytotoxic activity against ras-transformed cells.

Cytotoxicity tests in tumor cells sensitive to cis-DDP (HL-60, JURKAT, Hela and 3T3) and in tumor cells transformed by ras oncogenes and resistant to cis-DDP (Pam 212-ras) show that cyclometallated complexes 1a [Pd(p-is.TSCN-NHMe)]4, 2b [Pt(p-is.TSCN-NMe2)]4 and 4a [Pd(p-is.TSCN-NHex)]4 may be endowed with specific cytotoxic properties. In fact, these three novel metal-thiosemicarbazone compounds kill Pam 212-ras cells through apoptosis induction. These results, together with others recently published, indicate that the design and synthesis of metallated-thiosemicarbazone compounds may lead to the discovery of novel antitumor agents able to circumvent cis-DDP resistance, in particular tumor cell lines.

A cycloplatinated compound of p-isopropylbenzaldehyde thiosemicarbazone and its chloro-bridged derivative induce apoptosis in cis-DDP resistant cells which overexpress the H-ras oncogene.

cis-Diamminedichloroplatinum(II) (cis-DDP) is a widely used antitumour drug which produces important damage on the DNA inducing apoptosis in several cell lines. We have analyzed the cytotoxic activity of novel cyclometallated complexes of p-isopropylbenzaldehyde thiosemicarbazone (p-is.TSCN) and their dimeric chloro-bridged derivatives in murine keratinocytes transformed by the H-ras oncogene which are resistant to cis-DDP (Pam-ras cells). The data show that, in contrast with cis-DDP, the tetrameric cycloplatinated complex [Pt(p-is.TSCN)]4 and its dimeric chloro-bridged derivative [Pt(microCl)(p-is.TSCN)]2 have a good in vitro therapeutic index when comparing the cytotoxicity in Pam-ras cells to normal murine keratinocytes (Pam 212 cells) since they induce cell death in Pam-ras cells at drug concentrations significantly lower than those needed to kill Pam 212 cells. At equitoxic doses (IC90), both complexes produce characteristic features of apoptosis in Pam-ras cells together with a drastic decrease in levels of H-ras protein. These effects are not observed when the cells are treated with the IC90 of the cis-DDP drug nor the p-is.TSCN ligand. Altogether, these results suggest that the platinum compounds [Pt(p-is.TSCN)]4 and [Pt(microCl)(p-is.TSCN)]2 might have potential as antitumour agents in view of their specific induction of apoptosis in cis-DDP resistant cells.

Apoptosis induction and inhibition of H-ras overexpression by novel trans-[PtCl2(isopropylamine)(amine')] complexes.

Hitherto, it has been generally accepted as a paradigm of the biochemical pharmacology of platinum antitumor drugs that a cis configuration of the leaving groups is necessary for antitumor activity of platinum compounds. However, it has been recently observed that certain trans-platinum complexes have both in vitro and in vivo antitumor activity. We previously reported the synthesis, characterization and cytotoxic activity against ras-transformed cells of several trans-[PtCl2LL'] complexes where L and L' are asymmetric aliphatic amines (L = dimethylamine and butylamine, L' = isopropylamine). The results reported in this paper show that the compounds trans-[PtCl2(isopropylamine)(dimethylamine)] and trans-[PtCl2(isopropylamine)(butylamine)] kill Pam 212-ras cisplatin resistant cells through apoptosis induction. Moreover, Western blot data show that both compounds inhibit overexpression of H-ras oncogene in Pam 212-ras cells. Altogether, these data indicate that, in contrast with cis-DDP, the apoptotic activity of these novel trans-Pt(II) compounds in ras-transformed cells is associated with their ability to abolish ras-overexpression.

Combined effect of platination and intercalation upon DNA binding of novel cytotoxic Pt-bis(naphthalimide) complexes.

The reaction of platinum salts with bis(naphthalimide), compound 1, yielded two Pt-bis(naphthalimide) complexes, compounds 2 and 3 which differ from each other in their leaving groups being 1,1-cyclobutane dicarboxylate or chloride, respectively. The testing of the cytotoxic activity of compounds 2 and 3 against several tumor cell lines indicated that both compounds may be endowed with important antineoplastic properties since they circumvent cisplatin resistance. At similar rates of DNA platination (r(b) = 0.025), compounds 2 and 3 unwind supercoiled pUC8 DNA by (48 +/- 2) degrees. Altogether, these data suggest (i) that the cytotoxic activity of compounds 2 and 3 may be due to a combined effect of platination and intercalation and (ii) that the bis(naphthalimide) ligand is a suitable "carrier" that favors DNA targeting by cis-Pt(II) centers.

Binuclear chloro-bridged palladated and platinated complexes derived from p-isopropylbenzaldehyde thiosemicarbazone with cytotoxicity against cisplatin resistant tumor cell lines.

Two novel dimeric chloro-bridged complexes [Pd (p-is. TSCN) (mu-Cl)]2, 2, and [Pt (p-is. TSCN)(mu-Cl)]2, 3, where p-is. TSCN = p-isopropylbenzaldehyde thiosemicarbazone, 1, have been synthesized and characterized by IR and NMR spectroscopy. The in vitro antitumor activity shown by both compounds against several human and murine cell lines sensitive and resistant to the clinically-used drug cisplatin (cis-DDP) suggests that compounds 2 and 3 may be endowed with important anticancer properties. Thus, compounds 2 and 3 not only show IC50 values in the microM range as cis-DDP but also display cytotoxic activity in tumor cell lines resistant to this drug. The analysis of the interaction of these binuclear p-is. TSCN compounds with DNA secondary and tertiary structures indicate that they form DNA interhelical cross-links, a biochemical property that may be involved in their mechanism of action.

Palladated and platinated complexes derived from phenylacetaldehyde thiosemicarbazone with cytotoxic activity in cis-DDP resistant tumor cells. Formation of DNA interstrand cross-links by these complexes.

In the present paper we report the synthesis and characterization by 1H 13C NMR and heteronuclear 2D NMR spectroscopies of two new metallic complexes derived from phenylacetaldehyde thiosemincarbazone: Pt(C9H11N3S)Cl2, compound 2, and Pd(C9H11N3S)Cl2, compound 3. The testing of the cytotoxic activity of these compounds against several human and murine cell lines sensitive and resistant to cis-DDP suggests that compounds 2 and 3 may be considered potential anticancer agents since they exhibit 1C50 values in a microM range similar to cisplatin (cis-DDP). The cytotoxic activity of these compounds is higher in cis-DDP-resistant tumor cells than that of other antitumor drugs such as etoposide and adriamycin. On the other hand, the analysis of the interaction of compounds 2 and 3 with linear plasmid DNA indicate that both compounds, particularly compound 3, have an enhanced capacity to form DNA interstrand cross-links in comparison with cis-DDP.