Tumor Induction, Engraftment, and Treatment Protocols

For tumor induction, 3-week-old Braf/Pten mice were treated with 4-hydroxytamoxifen on the skin surface as described before to induce tumor formation^{49 (link)}. For tumor engraftment, 5 × 10⁴ cells YUMM1.7, B16-OVA, or one million1 × 10⁶ MC38 tumor cells were injected subcutaneously in 50 μl PBS. Tumors were measured every 2-3 days post tumor engraftment or indicated treatments and calculated. Tumor volume was calculated by volume = (length × width²)/2 for engrafted tumor or volume = (length × width × height) for inducible tumor. For in vivo treatment, Yumm1.7-bearing mice were administrated every 3 days with either DMSO or PPAR-β agonist (GW 501516) (1 mg per kg of body weight, Cayman Chemical) by intraperitoneal injection. For antibody-based treatment, tumor-bearing mice were treated with anti-PD-1 antibody (200 μg per injection, BioXcell, clone 29F.1A12) and anti-CD36 antibody (200 μg per injection, clone CRF D-2712 ^{50 (link)}, provided by R. Silverstein at Medical College of Wisconsin) according to indicated combination by intraperitoneal injection. For antibody treatment in the Braf/Pten mouse model, four weeks after tumor induction, tumor-bearing Braf/Pten mice were treated with anti-CD36 antibody and/or anti-PD-1 antibody as indicated above for a period of 10 days. All experiments were conducted according to Swiss federal regulations.