An herbal formula, SH003 alleviates colorectal cancer through dual targeting of adaptive and innate checkpoints PD-L1/CD47

Colorectal cancer (CRC) is the third most common cancer. The use of immunotherapy for cancer has become widespread in recent decades and adaptive and innate checkpoints can be simultaneously targeted for enhanced immunotherapy. An herbal formula, SH003 has beneficial effects against multiple cancers. However, the anti-CRC efficacy of SH003 through dual targeting of adaptive and innate checkpoints, PD-L1/CD47 remain to be investigated. We used two types of CRC patient-derived organoids (PDOs) and two types of CRC cell lines, and analyzed PD-L1 and CD47 expression levels with quantitative real-time PCR, Western blot, flow cytometry assays, and immunofluorescence staining. The cytotoxicity, proliferation, and apoptosis analysis were applied to clarify the regulatory effects on CRC growth. T cell immunity was analyzed through a co-culture system of CRC cell lines and T cells, as well as in in vivo CRC model. SH003 reduced the growth of CRC PDOs, leading to morphological changes and decreases in ATP and Ki67 levels. SH003 inhibited the mRNA and protein expression of both PD-L1 and CD47 though the regulation of c-Myc in CRC PDOs. In addition, SH003 suppressed VEGF, TNF-α, and IL-1β in CRC PDOs. This effect was validated in experiments of CRC cell lines, revealing that SH003 suppressed both PD-L1 and CD47 expression increased by IFN-γ stimulation via the regulation of c-Myc and reduced CRC progression. SH003 also enhanced the T cell-mediated killing of CRC cells with increased IL-2 production. In an in vivo CRC model, SH003 inhibited tumor growth while reducing both PD-L1, CD47, and c-Myc expression and increasing CD8 + T cell infiltration. Our investigation demonstrated that SH003 served as a novel CRC immunotherapy by the dual targeting of adaptive and innate checkpoints, PD-L1/CD47 via the regulation of c-Myc signaling, highlighting that SH003 may be an effective herbal candidate drug for the treatment of CRC.