- 作者: Chuang JH, Chuang HC, Huang CC, Wu CL, Du YY, Kung ML, Chen CH, Chen SC et al.
- 作者服務機構: Department of Surgery, Division of Pediatric Surgery, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Taiwan, R.O.C.
- 中文摘要: --
- 英文摘要:
Background: Toll-like receptor-3 (TLR-3) is a critical component of innate immune
system against dsRNA viruses and is expressed in the central nervous system.
However, it remains unknown whether TLR3 may serve as a therapeutic target in
human neuroblastoma (NB).
Methods: TLR3 expression in human NB samples was examined by
immunohistochemical analysis. Quantitative RT-PCR and western blot was used to
determine TLR3 expression in three human NB cell lines. The effect of TLR3 agonist,
polyinosinic-polycytidylic acid (poly(I:C)), on the growth of human NB cells was
evaluated by WST-1 cell proliferation assay, flow cytometry analysis, and
immunoblot analysis. Blockade of TLR3 signaling was achieved using TLR3
neutralizing antibody, small interference RNA, and 2-aminopurine (2-AP), an
inhibitor of protein kinase R (PKR), an interferon-induced, double-stranded
RNA-activated protein kinase.
Results: In immunohistochemical studies, TLR3 mainly expressed in the cytoplasm of
ganglion cells and in some neuroblastic cells, but not in the stromal cells in human NB
tissues. Among three human NB cell lines analyzed, TLR3 was significantly
up-regulated in SK-N-AS cells at mRNA and protein level compared with other two
low TLR3- expressing NB cells. Treatment with poly(I:C) elicited significant growth inhibition and apoptosis only in high TLR3-expressing SK-N-AS cells, but not in low
TLR3-expressing SK-N-FI and SK-N-DZ cells. Moreover, poly(I:C) treatment
significantly stimulated the activities of PKR, interferon regulatory factor 3 (IRF-3)
and caspase-3 in SK-N-AS cells. Application of TLR3 neutralizing antibody or small
interference RNA (siRNA) reduced the poly(I:C)-induced inhibition of cell
proliferation and apoptosis in SK-N-AS cells. On the contrary, ectopic TLR3
expression enhanced the sensitivity of low TLR3-expressing NB cells to poly(I:C).
Finally, application of 2-AP attenuated the poly(I:C)-induced IRF-3 and caspase-3
activation in SK-N-AS cells.
Conclusion: The present study demonstrates that TLR3 is expressed in a subset of
NB cells. Besides, TLR3/PKR/IRF-3/capase-3 pathway is implicated in the selective
cytotoxicity of TLR3 agonist towards high TLR3-expressing NB cells. - 中文關鍵字: --
- 英文關鍵字: neuroblastoma; toll-like receptor 3; poly(I:C); apoptosis