For in vitro studies, 6-thio-dG (Metkinen Oy, Kuopio, Finland) was dissolved in DMSO/water (1:1) to prepare 10 mM stock solutions, which were kept frozen at −20°C. A 1 mM, final concentration stock was prepared for in vitro experiments and added in fresh medium at different concentrations. Erlotinib HCl (Selleckchem, Houston, TX) was dissolved in DMSO to prepare 10 mM stock solutions, which were kept frozen at −80°C. A 2.5 μM erlotinib final concentration was used for in vitro experiments. Osimertinib and paclitaxel (Selleckchem) were dissolved in DMSO, and carboplatin (Selleckchem) was dissolved in water to prepare 10 mM stock solutions, which were kept frozen at −80°C. A 1 mM final concentration stock was prepared for in vitro experiments and added in fresh medium at different concentrations.
For mouse in vivo studies, 6-thio-dG was prepared in 5% DMSO for intraperitoneal (i.p.) injection or 0.4% (hydroxypropyl)methyl cellulose (Sigma, Saint Louis, MO) for oral gavage. Erlotinib was prepared in 15% Captisol (β-cyclodextrin, sulfobutyl ethers, sodium salts) (Cydex Pharmaceuticals, Lawrence, KS) for oral gavage. Gemcitabine HCl and cisplatin (Selleckchem) were dissolved in 0.9% NaCl saline solution for i.p. injections.
For mouse in vivo studies, 6-thio-dG was prepared in 5% DMSO for intraperitoneal (i.p.) injection or 0.4% (hydroxypropyl)methyl cellulose (Sigma, Saint Louis, MO) for oral gavage. Erlotinib was prepared in 15% Captisol (β-cyclodextrin, sulfobutyl ethers, sodium salts) (Cydex Pharmaceuticals, Lawrence, KS) for oral gavage. Gemcitabine HCl and cisplatin (Selleckchem) were dissolved in 0.9% NaCl saline solution for i.p. injections.