Targeting MDSC infiltration and tumor angiogenesis in orthotopic RM-1 prostate tumors. RM-1 prostate tumor cells were implanted intraprostatically in the dorsolateral lobes of C57BL/6 males. Mice were treated with control diluent, GW2580, PBS, or clodronate liposomes (Clodrolip) at the appropriate dosing regimen. (A) Peripheral blood (n = 5/group) total MDSCs were analyzed by flow cytometry in control (white bar) and GW2580-treated (black bar) mice. (B) Tumor-associated MDSC levels (n = 3-5/group) were also analyzed by flow cytometry in control and GW580-treated mice. (C) Tumor tissue was processed and subjected to histologic staining of F4/80⁺ TAMs at the peritumoral regions (top) and normal prostate-tumor interface (bottom). (D) Representative CD31⁺ blood and Lyve-1⁺ lymphatic vascular staining of RM-1 prostate tumors from control and GW2580-treated mice are shown. Quantification of CD31⁺ (E) and Lyve-1⁺ (F) area was performed using ImageJ software (n = 3-5/group). (G-H) Peripheral blood (n = 5/group) and tumor-associated MDSC (n = 3 or 4/group) levels were analyzed by flow cytometry in PBS- (white bar) and Clodrolip-treated (gray bar) mice. Genitourinary tract (GUT) weight was measured at endpoint in GW2580-treated (I) and Clodrolip-treated (J) mice (n = 3-5/group). Scale bars represent 100 μm.