Figure 6. Anti-tumorigenic, anti-angiogenic and immunostimulating effects of sIFN-I in immunocompetent mouse models.

A. YUMM (Braf^V600E/+; Pten^Δ/Δ; CDKN2A^−/−) cells were injected subcutaneously into Ifnar1^+/+ and Ifnar1^−/− mice to establish transplantable tumor model. sIFN-I or IFNα-2b (5 mg/kg) were injected intraperitoneally every other day for the indicated days. The tumor volume was measured and calculated.

B. H&E and immunofluorescence staining of YUMM tumors isolated from mice after sIFN-I treatment. Arrows indicate the vessels in tumor tissue. Scale bar, 100 μm.

C. Quantification on the positive CD31⁺ vessels number in the fields (n=7) and CD3⁺CD8⁺ T cells infiltrated in YUMM allograft tumor microenvironment (n=10).

D. Melanocyte-specific Cre activity was induced in adult mice (Braf^CA/+Pten^f/f) by topical application of 4-HT to shaved back skin. Melanoma growth was measured after intraperitoneal injection with sIFN-I every other day.

E. Volume of melanoma tumors that grew in Braf^V600E/+; Pten^Δ/Δ mice to initial volume (“-”, blue circles). After that, mice were randomly assigned to two groups treated with PBS (black squares, left mouse in the inset) or sIFN-I (red triangles, right mouse at inset) for 32 days. p<0.001 between PBS and sIFN-I group.

F. Immunofluorescence staining of the tumor isolated from Braf^V600E/+; Pten^Δ/Δ mice after sIFN-I treatment. Bottom, quantification on the average positive CD31⁺ vessels number in the fields (n=10) and the double positive CD3⁺CD8⁺ cells in the fields (n=10) presenting infiltrated effector T cells in tumors from Braf^V600E; Pten^Δ/Δ mice. Scale bar: 100 μm.

G. H&E staining of the tumors and superficial lymph nodes (n=12) isolated from Braf^V600E/+; Pten^Δ/Δ mice after sIFN-I treatment. Bottom, quantification on the number of metastatic tumors in lymph node (LN). Scale bar, 100 μm.