Inhibition of mouse spleen cell activity by organotin compounds: effect of attachment of a maltose residue to the organotin group

p53-dependent antiproliferative and antitumor effect of novel alkyl series of diorganotin(IV) compounds

PURPOSE

A series of diorganotin(IV) dichloride complexes of N-(2-pyridylmethylene)arylamine (nitrogen-chelating ligands) have been synthesized and characterized. The present study was carried out to investigate the comparative anti-proliferative and anti-tumor effect of Me(2)SnCl(2.)L(1) (OTC-1), Et(2)SnCl(2.)L(2) (OTC-2) and (n)Bu(2)SnCl. L(2) (OTC-3) in combination with X-rays (1.5 Gy).

METHOD

The cytotoxicity of these diorganotin(IV) compounds was studied in human peripheral lymphocytes and the antitumor activity was assessed in Dalton's lymphoma cells. The involvement of proteins that regulate cell cycle and apoptosis was investigated to elucidate the mechanism of their action.

RESULTS

5 mg kg(-1) of OTC-3 showed better antiproliferative and antitumor activity than OTC-1 and OTC-2, both as alone or in combination with X-rays. The maximum enhancement of exchange aberrations and the level of p53 and p16 proteins were observed in the OTC-3 treated samples. Upregulated expression of p53 caused a significant down-regulated transcriptionally repression of Survivin in OTC-3 treated human lymphocytes.

CONCLUSION

It could be possible that after treatment with either OTC-3 alone or in combination with X-rays the Dalton's lymphoma cells may die apoptotically after inducing initial delay in cell cycle and thereby survivality of mouse bearing Dalton's Lymphoma cells was increased significantly.

Cell proliferation inhibition and antitumor activity of novel alkyl series of diorganotin(IV) compounds

Diorganotin(IV) compounds, R2SnCl2 are often tetrahedral, and structurally resemble the active platinum compounds, i.e. cisplatin, and consequently a large number of such complexes have been tested for antitumor activity. A structural correlation with biological activity for diorganotin(IV) complexes has shown that active species are associated with complexes having Sn-N bonds longer than 2.39 A which in turn determines the formation of a tin-DNA complex. In view of these, a series of diorganotin(IV) dichloride complexes of N-(2-pyridylmethylene)arylamine (nitrogen-chelating ligands) has been synthesized and characterized on the basis of IR, NMR and 119Sn-Mössbauer studies. In the present study, an attempt was made to determine the comparative antiproliferative and antitumor effect of diorganotin(IV) complexes with different alkyl groups [Me2SnCl2.L1 (OTC-1), Et2SnCl2.L2 (OTC-2) and (n)Bu2SnCl2.L2 (OTC-3)]. The present study in human lymphocytes demonstrated that these diorganotin(IV) complexes could block the cell cycle progression and induce sister chromatid exchanges (SCEs) significantly, however, with respect to the induction of chromosome aberrations (CAs) it was very mild. Both the levels of p53 and p16 proteins were raised after diorganotin(IV) treatment and such induction was maximum in the OTC-3 treated samples. The antitumor activity was determined in accordance with the US National Cancer Institute (NCI) standard protocol for primary screening in Dalton's lymphoma that was maintained by serial intraperitoneal transplantation. The T/C (treated/control) value was increased (186% with OTC-3) when diorganotin(IV) was given after transplantation. The data suggest that the OTC-3 has better antiproliferative and antitumor activity and endogenous glutathione level has no influence on the effect of OTC-3.

Antiproliferative and cytotoxic effect of a novel organotin compound on mammalian cells both in vitro and in vivo

Organotin compounds are organometallic compounds showing various toxicological properties. Several organotin compounds also showed an antineoplastic effect. However, their relative mutagenic potential is not well established. In this study Et(2)SnCl(2).L [L=N-(2-pyridylmethylene)-4-toluidine] (OTC) has been subjected to investigation for its cytotoxic effect in mouse bone marrow cells (BMCs) and human peripheral blood lymphocyte cells (HPBLs). The Sn [bond] N bond in OTC is 2.46A which is greater than 2.39A and therefore, a better formation of tin-DNA complex can be expected. The present data indicate that OTC induced significant delay in cell kinetics and sister chromatid exchanges (SCEs) in both BMCs and HPBLs, whereas, induction of chromosome aberrations was found only in HPBLs. The presence of buthionine sulfoximine (BSO) modulated cellular sensitivity towards OTC in both cell systems. It may be inferred that the OTC could bind on DNA more easily owing to its structural advantage and this may explain the induction of DNA damage and the delay in cell proliferation. Since the cytotoxic effect of OTC is more in glutathione depleted cells, the concentration of OTC may be reduced to get an antitumour effect in GSH-depleted cells and thus minimizes its toxic side effect.

Organotin compounds decrease in vitro survival, proliferation and differentiation of normal human B lymphocytes

Organotin compounds (OTC) are organometallic compounds with vast industrial and agriculture applications that give rise to ubiquitous environmental contamination. OTC are immunotoxic, but most studies have been performed in rodents and almost exclusively focused on T cell immunity. Humans can be exposed to OTC by inhalation, absorption, and consumption of contaminated food and water. To analyse the effects of OTC in human immune tissue, we isolated B cells from tonsils and exposed them to five OTC at various concentrations, during in vitro culture. Non-stimulated B cells were killed by 100 nM of all tested OTC after 8 h in vitro culture, under sub-optimal conditions, except TET. OTC also decreased the proliferation of tonsillar B lymphocytes stimulated with Staphylococcus aureus Cowan 1 (SAC) and IL-2, when present at 100 nM and higher concentrations. IgM secretion was reduced in stimulated cell cultures exposed to 100 nM dibutyltin chloride (DBT). Accordingly, increased phosphatidylserine exposure demonstrated that 100 nM TPT and DBT induced B cells to die by apoptosis. These data indicate that human B cells are diminished in their capacity to survive, proliferate and differentiate in the presence of OTC in vitro.