Diorganotin(IV) and triorganotin(IV) complexes of meso-tetra(4-sulfonatophenyl)porphine induce apoptosis in A375 human melanoma cells

Dibutyltin(IV) and Tributyltin(IV) Derivatives of meso-Tetra(4-sulfonatophenyl)porphine Inhibit the Growth and the Migration of Human Melanoma Cells

Melanoma is the most aggressive and deadly form of skin cancer, which is largely due to its propensity to metastasize. Therefore, with the aim to inhibit the growth and the metastatic dissemination of melanoma cells and to provide a novel treatment option, we studied the effects of the melanoma treatment with two organotin(IV) complexes of the meso-tetra(4-sulfonato-phenyl)porphine, namely (Bu2Sn)2TPPS and (Bu3Sn)4TPPS. In particular, we showed that nanomolar concentrations of (Bu2Sn)2TPPS and (Bu3Sn)4TPPS are sufficient to inhibit melanoma cell growth, to increase the expression of the full-length poly (ADP-ribose) polymerase (PARP-1), to induce the cell cycle arrest respectively at G2/M and G0/G1 through the inhibition of the Cyclin D1 expression and to inhibit cell colony formation. Nanomolar concentrations of (Bu2Sn)2TPPS and (Bu3Sn)4TPPS are also sufficient to inhibit the melanoma cell migration and the expression of some adhesion receptors. Moreover, we report that (Bu2Sn)2TPPS and (Bu3Sn)4TPPS act downstream of BRAF, mainly bypassing its functions, but targeting the STAT3 signalling protein. Finally, these results suggest that (Bu2Sn)2TPPS and (Bu3Sn)4TPPS may be effective therapeutic strategies for their role in the inhibition of melanoma growth and migration.

Apoptosis induced by 9,11‑dehydroergosterol peroxide from Ganoderma Lucidum mycelium in human malignant melanoma cells is Mcl‑1 dependent

9,11-Dehydroergosterol peroxide [9(11)-DHEP] is an important steroid from medicinal mushroom, which has been reported to exert antitumor activity in several tumor types. However, the role of 9(11)-DHEP toward the malignant melanoma cells has not been investigated. In the present study, the steroid from Ganoderma lucidum was purified on a submerged culture, and its antitumor mechanisms on A375 human malignant melanoma cells was investigated by MTT, flow cytometry and western blotting. The studies demonstrated that apoptotic mechanisms of the steroid were caspase-dependent and mediated via the mitochondrial pathway. The steroid did not cause significant changes in the expression levels of B-cell lymphoma 2 (Bcl-2) family proteins, Bcl-2-like protein 11, p53 upregulated modulator of apoptosis, Bcl-2-associated X protein, BH3 interacting-domain death agonist, Bcl-2-associated death promoter and Bcl-2, but it significantly downregulated induced myeloid leukemia cell differentiation protein Mcl-1 (Mcl-1) in melanoma cells, suggesting the key role of Mcl-1 in regulating apoptosis of melanoma cells induced by the steroid. These properties of 9(11)-DHEP advocate its usage as supplements in human malignant melanoma chemoprevention. The present study also suggests that mycelium of G. lucidum has a potential for producing bioactive substances and extracts with applications in medicine.

Studies on DNA interaction of organotin(IV) complexes of meso-tetra(4-sulfonatophenyl)porphine that show cellular activity

The interaction of the diorgano- and triorganotin(IV) derivatives of meso-tetra-(4-sulfonatophenyl)porphine (Me₂Sn)₂TPPS, (Bu₂Sn)₂TPPS, (Me₃Sn)₄TPPS and (Bu₃Sn)₄TPPS to natural DNA was analysed (together with free meso-tetra-(4-sulfonatophenyl)porphine (TPPS^4-) for comparison purposes). Particular attention was paid to (Bu₃Sn)₄TPPS, a species that shows significant cellular action. Preliminary tests were done on the solution properties of the organotin(IV) compounds (pK_A and possible self-aggregation). Spectrophotometric and spectrofluorometric experiments showed that all the investigated organotin(IV) derivatives strongly interact with DNA, the binding energy depending on the dye steric hindrance. In all cases experimental data concur in indicating that external binding mode prevails. Interestingly, fluorescence quenching and viscosity experiments show that the Bu-containing species, and in particular (Bu₃Sn)₄TPPS, are able to noticeably alter the DNA conformation.

Anticancer and cytotoxic effects of a triorganotin compound with 2-mercapto-nicotinic acid in malignant cell lines and tumor bearing Wistar rats

Nowadays, investigation for possible therapeutic applications of various metal-based drugs attracts the scientific interest worldwide. The triorganotin compound bis[triphenyltin(IV)](3-carboxy-pyridine-2-thionato) (SnMNA), was tested for its anti-proliferative and antitumor activities. Cytotoxic activity was assessed by Trypan blue and 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide assay (MTT). SnMNA exhibited potent cytotoxic effects against leiomyosarcoma cells (LMS) and human breast adenocarcinoma cells (MCF-7), which is 200 times stronger than that of cisplatin. Moreover, SnMNA induced significant apoptosis in LMS and MCF-7 cells characterized by flow cytometry analysis and DNA fragmentation. Acute and chronic toxicity studies on Wistar rats caused kidney and lung toxicity at a single dose of 80mg/kgBody Weight (BW) or four repeated doses of 8mg/kgBW once per week. Furthermore, antitumor activity studies on sarcoma bearing Wistar rats revealed that SnMNA complex at four repeated doses of 5.4mg/kgBW every three days prolonged mean survival time of the animal at 200% and decreased mean tumor growth rate (MTGR) compared to the control group (p<0.05). It is noteworthy to mention that the 30% (3 out of 10) of the bearing animals were totally cured. These findings indicate that SnMNA might be a promising new antitumor agent.

Pseudoenzymatic dealkylation of alkyltins by biological dithiols

We investigated the time dependence of the degradation of three alkyltin derivatives by a nine amino acid linear peptide (I(1)LGCWCYLR(9)) containing a CXC motif derived from the primary sequence of stannin, a membrane protein involved in alkyltin toxicity. We monitored the reaction kinetics using the intrinsic fluorescence of the tryptophan residue in position 5 of the peptide and found that all of the alkyltins analyzed are progressively degraded to dialkyl derivatives, following a pseudoenzymatic reaction mechanism. The end point of the reactions is the formation of a covalent complex between the disubstituted alkyltin and the peptide cysteines. These data agree with the speciation profiles proposed for polysubstituted alkyltins in the environment and reveal a possible biotic degradation pathway for these toxic compounds.

Toxicogenomics of A375 human malignant melanoma cells

Toxicogenomics applications are increasingly applied to the evaluation of preclinical drug safety, and to explain toxicities associated with compounds at the mechanism level. In this review, we aim to describe the application of toxicogenomics tools for studying the genotoxic effect of active compounds on the gene-expression profile of A375 human malignant melanoma cells, through the other molecular functions of target genes, regulatory pathways and mechanisms of malignant melanomas. It also includes the current systems biology approaches, which are very useful for analyzing the biological system and understanding the entire mechanisms of malignant melanomas. We believe that this review would be very potent and useful for studying the toxicogenomics of A375 melanoma cells, and for further diagnostic and therapeutic applications.