Telomeric G-quadruplex-forming DNA fragments induce TLR9-mediated and LL-37-regulated invasion in breast cancer cells in vitro

A1 Originalartikel i en vetenskaplig tidskrift (referentgranskad)


Interna författare/redaktörer


Publikationens författare: Tuomela JM, Sandholm JA, Kaakinen M, Hayden KL, Haapasaari KM, Jukkola-Vuorinen A, Kauppila JH, Lehenkari PP, Harris KW, Graves DE, Selander KS
Förläggare: SPRINGER
Publiceringsår: 2016
Tidskrift: Breast Cancer Research and Treatment
Tidskriftsakronym: BREAST CANCER RES TR
Volym: 155
Nummer: 2
Artikelns första sida, sidnummer: 261
Artikelns sista sida, sidnummer: 271
Antal sidor: 11
ISSN: 0167-6806
eISSN: 1573-7217


Abstrakt

Toll-like receptor 9 (TLR9) is a cellular DNA-receptor widely expressed in cancers. We previously showed that synthetic and self-derived DNA fragments induce TLR9-mediated breast cancer cell invasion in vitro. We investigated here the invasive effects of two nuclease-resistant DNA fragments, a 9-mer hairpin, and a G-quadruplex DNA based on the human telomere sequence, both having native phosphodiester backbone. Cellular uptake of DNAs was investigated with immunofluorescence, invasion was studied with Matrigel-assays, and mRNA and protein expression were studied with qPCR and Western blotting and protease activity with zymograms. TLR9 expression was suppressed through siRNA. Although both DNAs induced TLR9-mediated changes in pro-invasive mRNA expression, only the telomeric G-quadruplex DNA significantly increased cellular invasion. This was inhibited with GM6001 and aprotinin, suggesting MMP- and serine protease mediation. Furthermore, complexing with LL-37, a cathelicidin-peptide present in breast cancers, increased 9-mer hairpin and G-quadruplex DNA uptake into the cancer cells. However, DNA/LL-37 complexes decreased invasion, as compared with DNA-treatment alone. Invasion studies were conducted also with DNA fragments isolated from neoadjuvant chemotherapy-treated breast tumors. Also such DNA induced breast cancer cell invasion in vitro. As with the synthetic DNAs, this invasive effect was reduced by complexing the neoadjuvant tumor-derived DNAs with LL-37. We conclude that 9-mer hairpin and G-quadruplex DNA fragments are nuclease-resistant DNA structures that can act as invasion-inducing TLR9 ligands. Their cellular uptake and the invasive effects are regulated via LL-37. Although such structures may be present in chemotherapy-treated tumors, the clinical significance of this finding requires further studying.


Nyckelord

9-mer hairpin DNA, LL-37, Telomeric G-quadruplex DNA, Toll-like receptor 9

Senast uppdaterad 2019-20-10 vid 04:07