Toll-like receptor 9 (TLR9) is a DNA receptor of innate immune system which plays a pivotal role in inflammatory response. Recent evidence reveals over-expression and functionality of TLR9 in a wide variety of cancer cells and its contribution to tumor cell proliferation and survival.
OBJECTIVE:
In this study, we assessed the aberrant cell surface expression of TLR9 in cancer using cell-lines model.
METHODS:
Three breast cancer cell-lines (MDA-MB-231, MCF7 and SKBR3) and five colorectal adenocarcinoma cell-lines (HT29, HT29/219, SW480, SW48 and SW1116) in addition to one primary foreskin isolated fibroblast cell were analyzed for cell surface and intracellular expression of TLR9 by flow cytometry method.
RESULTS:
Maximum surface expression of TLR9 was observed in colorectal cell-line HT29/219 (38.35%), as compared with the bottom line fibroblast normal cells (0.12%). The most intracellular expression was observed in MCF-7 cells (35.63%), whereas MDA-MB-231 expressed the maximum surface/intra cellular expression (277 times).
CONCLUSIONS:
Based on the results, we hypothesize that aberrant surface expression of TLR9 on tumor cells may promote tumor growth and invasion. It might also highlight a dual contradictory role for CpG-ODNs, as adjutant in cancer therapy.
PradereJ.P., DapitoD.H. and SchwabeR.F., The Yin and Yang of Toll-like receptors in cancer, Oncogene33(27) (2014), 3485-95.
4.
O'NeillL.A.J., GolenbockD. and BowieA.G., The history of Toll-like receptors - redefining innate immunity, Nature Reviews Immunology13(6) (2013), 453-460.
5.
AshkarA.A. and RosenthalK.L., Toll-like receptor 9, CpG DNA and innate immunity, Curr Mol Med2(6) (2002), 545-56.
6.
FuriI., SiposF., SpisákS., KisznerG., WichmannB. et al., Association of self-DNA mediated TLR9-related gene, DNA methyltransferase, and cytokeratin protein expression alterations in HT29-cells to DNA fragment length and methylation status, The Scientific World Journal (2013), 8.
MerrellM.A. et al., Toll-like receptor 9 agonists promote cellular invasion by increasing matrix metalloproteinase activity, Mol Cancer Res4(7) (2006), 437-47.
9.
NojiriK., SugimotoK., K Shiraki and TamedaM., The expression and function of Toll-like receptors 3 and 9 in human colon carcinoma, Oncology Reports29 (2013), 7.
10.
YusufN., Toll-like receptor mediated regulation of breast cancer: A case of mixed blessings, Front Immunol5 (2014), 224.
11.
SandholmJ. et al., Hypoxia regulates Toll-like receptor-9 expression and invasive function in human brain cancer cells in vitro, Oncol Lett8(1) (2014), 266-274.
12.
TanakaJ., SugimotoK., ShirakiK. and TamedaM., Functional cell surface expression of Toll-like receptor 9 promotes cell proliferation and survival in human hepatocellular carcinomas, International Journal of Oncology37 (2010).
13.
BergerR., Toll-like receptor 9 expression in breast and ovarian cancer is associated with poorly differentiated tumors, Cancer Sci101(4) (2010), 7.
14.
MerrellJ.M.I., LehtonenN. et al., Toll-like receptor 9 agonists promote cellular invasion by increasing matrix metalloproteinase activity, Mol Cancer Res4 (2006).
15.
TuomelaJ. et al., DNA from dead cancer cells induces TLR9-mediated invasion and inflammation in living cancer cells, Breast Cancer Res Treat142(3) (2013), 477-87.
16.
FuriI. et al., Cell free DNA of tumor origin induces a `Metastatic' expression profile in HT-29 cancer cell line, PLoS One10(7) (2015), e0131699.
17.
KauppilaJ.H. et al., Short DNA sequences and bacterial DNA induce esophageal, gastric, and colorectal cancer cell invasion, APMIS121(6) (2013), 511-22.
18.
KorvalaJ., HarjulaT., SiirilaK., AlmangushA. et al., Toll-like receptor 9 expression in mucoepidermoid salivary gland carcinoma may associate with good prognosis, J Oral Pathol Med43 (2014), 7.
19.
RonkainenH. et al., Absent Toll-like receptor-9 expression predicts poor prognosis in renal cell carcinoma, J Exp Clin Cancer Res30 (2011), 84.
20.
BartonG.M., KaganJ.C. and MedzhitovR., Intracellular localization of Toll-like receptor 9 prevents recognition of self DNA but facilitates access to viral DNA, Nat Immunol7(1) (2006), 49-56.
21.
GuerrierT., PochardP., LahiriA., YouinouP. and PersJ.-O., Christophe Jamin TLR9 expressed on plasma membrane acts as a negative regulator of human B cell response, Journal of Autoimmunity51 (2014), 7.
22.
Eaton-BassiriA., DillonS.B., CunninghamM., RycyzynM.A., MillsJ., SariskyR.T. et al., Toll-like receptor 9 can be expressed at the cell surface of distinct populations of tonsils and human peripheral blood mononuclear cells, Infect Immun72 (2004), 9.
23.
AhmedD., EideP.W., EilertsenI.A., DanielsenS.A. et al., Epigenetic and genetic features of 24 colon cancer cell lines, Oncogenesis2 (2013), 7.
24.
DeK.S., VanH.E., KorthagenN., GarssenJ. and WillemsenL.E., Apical TLR ligation of intestinal epithelial cells drives a Th1-polarized regulatory or inflammatory type effector response in vitro, Immunobiology216 (2011), 9.
25.
LeeJ., MoJ.-H., ShenC., RuckerA.N. and RazE., Toll-like receptor signaling in intestinal epithelial cells contributes to colonic homoeostasis, Curr Opin Gastroenterol23 (2007), 4.
26.
KristinaS., Jin-FengL., LaurieB., TameraS., DawnC., PattiC., XingL., HungM.-C., ThomasB., HicksD.G. and TangP., The expression patterns of ER, PR, HER2, CK5/6, EGFR, Ki-67 and AR by immunohistochemical analysis in breast cancer cell lines, Breast Cancer: Basic and Clinical Research4 (2010), 7.
27.
ImbertA.-M., GarulliC., ChoquetE., KoubiM., Aurrand-LionsM. and ChabannonC., CD146 expression in human breast cancer cell lines induces phenotypic and functional changes observed in epithelial to mesenchymal transition, PLoS One7(8) (2012).
28.
SandholmJ. et al., Estrogen receptor-alpha and sex steroid hormones regulate Toll-like receptor-9 expression and invasive function in human breast cancer cells, Breast Cancer Res Treat132(2) (2012), 411-9.
29.
TuomelaJ. et al., Low TLR9 expression defines an aggressive subtype of triple-negative breast cancer, Breast Cancer Res Treat135(2) (2012), 481-93.
30.
MeseureD. et al., Biopathological significance of TLR9 expression in cancer cells and tumor microenvironment across invasive breast carcinomas subtypes, Cancer Microenviron, 2016.
31.
TarragonaM. et al., Identification of NOG as a specific breast cancer bone metastasis-supporting gene, J Biol Chem287(25) (2012), 21346-55.
32.
SheridanC., KishimotoH., FuchsR.K., MehrotraS., Bhat-NakshatriP., TurnerC.H., GouletR., Jr, BadveS. and NakshatriH., CD44+/CD24- breast cancer cells exhibit enhanced invasive properties: An early step necessary for metastasis, Breast Cancer Research8(5) (2006).
33.
ZhangY., WangQ., MaA., LiY., LiR. and WangY., Functional expression of TLR9 in esophageal cancer, Oncology Reports31 (2014).
34.
WangC. et al., TLR9 expression in glioma tissues correlated to glioma progression and the prognosis of GBM patients, BMC Cancer10 (2010), 415.
