Ta. Thompson et al., INDUCTION OF APOPTOSIS BY ORGANOTIN COMPOUNDS IN-VITRO - NEURONAL PROTECTION WITH ANTISENSE OLIGONUCLEOTIDES DIRECTED AGAINST STANNIN, The Journal of pharmacology and experimental therapeutics, 276(3), 1996, pp. 1201-1215
Immortalized cell lines and primary neuronal cultures were used to cha
racterize the selective toxicity of trimethyltin (TMT), triethyltin (T
ET) and tributyltin (TBT). TBT and TET were cytotoxic at similar conce
ntrations in the immortalized cell lines tested; the 50% toxic concent
ration (TC50) was 1 to 11 mu M. In contrast, immortalized cell lines v
aried considerably in their sensitivity to TMT, with sensitive cell li
nes (neuroblastomas, T-, B-cell lines) showing TC50 values of 2 to 8 m
u M, whereas insensitive cells (NIH-3T3 fibroblast, HTB-14 glioma, TC-
7 kidney cells) had TC50 values > 100 mu M. Primary neuronal cell cult
ures were very sensitive to organotins (TC50 similar to values, 1-10 n
M), and showed patterns of selective toxicity with respect to neuronal
and glial cells. Because organotin toxicity evolves over 24 to 48 hr,
we determined whether these compounds induced apoptosis in primary cu
ltures. TMT increased (P < .05) the fraction of apoptotic cells 6 and
12 hr after treatment with TMT at TC50 concentrations. Prior studies s
uggested that a protein, stannin, was localized in cells sensitive to
organotins, Stannin was expressed in several TMT-sensitive cell lines
(PC12, T, B cells) and in primary neurons in culture. Stannin was abse
nt in the resistant HTB-14 glioma cell line, The role of stannin in me
diating TMT toxicity in primary cultures was investigated by blocking
stannin expression with specific antisense oligonucleotides. Treatment
of primary cultures with antisense oligonucleotides for 48 hr before
and during TMT treatment significantly protected neurons from the neur
otoxic and apoptotic effects of TMT, This effect was not observed with
scrambled oligonucleotide controls. Thus, TMT may induce apoptosis in
sensitive cells, which is partly mediated by stannin. Based on the av
ailable data, we conclude that stannin expression is necessary, but no
t sufficient for TMT toxicity.