B16 murine melanoma cells stably expressing shRNAMyD88

NÚÑEZ, NICOLÁS; NOCERA, DAVID; RIVERO, VIRGINIA; MACCIONI,

Congreso; FIRST FRENCH-ARGENTINE IMMUNOLOGY CONGRESS. FAIC 2010; 2010

Sociedad Argentina Inmunologia

Toll-like receptors (TLRs) recognize molecules derived from pathogens (PAMPs) as well as endogenous danger signals possessing similar chemical structures (DAMPs). Upon recognition of their ligands, TLRs transduce signals through two pathways involving distinct adaptors, Toll/IL-1R domain–containing adaptor inducing IFNs (TRIF) and Myeloid differentiation primary response protein (MyD88), which is used by all TLRs except TLR3. Stimulation of TLRs-pathways on antigen presenting cells has always been considered a valuable tool to activate an anticancer immune response. Recently, the presence of functional TLRs in different tumor cell lines and in ex-vivo tumor samples has been demonstrated, raising the question about the role that these TLRs could be playing in sterile environments like tumors. Here, we investigated whether MyD88-dependent signaling modulates tumor development. The expression of MyD88 was stably knocked down in the B16 melanoma cell line (B16-MyD88kd) by using a silencing vector expressing short hairpin RNA (shRNA) targeting mouse MyD88. As control, we generated B16 cells stably transfected with the control vector encoding shRNA targeting luciferase gene (B16-Luc). These vectors encode GFP fusion protein for tracking the transfected cells. The expression of MyD88 in B16-MyD88kd and in B16- Luc was evaluated by qRTPCR. Approximately, a 65% of inhibition in mRNA expression of MyD88 was observed in B16-MyD88kd. Interestingly, when B16- MyD88kd were inoculated in vivo into syngeneic host, the tumors elicited were bigger than those elicited by B16-Luc (p<0.05). Our preliminary results indicate that in physiological conditions, an endogenous ligand could ordinarily activate this pathway and promoting a reduced tumor growth.