(A) Five pairs of shredded CRC and corresponding NT tissues suspended in basic medium were placed in the upper chamber of a 24-well Transwell system with polycarbonate filters. Thereafter, HUVECs were seeded in the bottom layer grown for 48 hours. Then, OX40 expression in HUVECs was measured by quantitative real-time PCR (qRT-PCR) (n = 3). (B–D) OX40 expression was measured in HUVECs treated with media derived from the indicated cells using qRT-PCR (n = 3). (E) HUVECs were treated with indicated media for 48 hours and then subjected to reverse chromatin immunoprecipitation analyses. The heatmap displays potential transcription factors that interact with OX40 promoter. (F) HUVECs were first treated with media derived from Lgr5^– and Lgr5⁺ SW480 cells and then exposed to DMSO or the STAT3 inhibitor Stattic (10 μM). OX40 expression was evaluated in HUVECs by qRT-PCR (n = 3). (G) Luciferase activity of the OX40 promoter in HUVECs treated with DMSO or the STAT3 inhibitor Stattic (n = 3). (H and I) Expression of 70 angiogenesis-associated cytokines was evaluated in tumor epithelial cells (Epi) (H) and Lgr5⁺ tumor epithelial cells (I) compared with their corresponding controls using scRNA-Seq data. (J) EGF levels were measured in media derived from the indicated cells using enzyme-linked immunosorbent assay (n = 3). (K) OX40 expression was evaluated in HUVECs treated with vehicle or exogenous EGF using qRT-PCR (n = 3). (L) First, scrambled NC (siNC) or siRNAs against EGF were transfected into Lgr5⁺ SW480 cells for 72 hours. Then, HUVECs were exposed to media derived from these cells. OX40 expression was evaluated in HUVECs using qRT-PCR (n = 3). One-way ANOVA (A, C, F, and J–L) or 2-tailed Student’s t test (D and G) was used for statistical analysis.