Anti-Cancer Effects of a New Herbal Medicine PSY by Inhibiting the STAT3 Signaling Pathway in Colorectal Cancer Cells and Its Phytochemical Analysis

Colorectal cancer (CRC) is an inflammation-associated common cancer worldwide. Paejang-san and Mori Cortex Radicis have been traditionally used for treating intestinal inflammatory diseases in Korea and China. In the present study, we developed a new herbal formula as an alternative to CRC treatments, which is composed of two main components of Paejangsan (Patriniae Radix (Paejang in Korean) and Coix Seed (Yiyiin in Korean)), and Mori Cortex Radicis (Sangbekpi in Korean) based on the addition and subtraction theory in traditional medicine, hence the name PSY, and explored the potential therapeutic effects of the new formula PSY in human CRC cells by analyzing viability, cell cycle and apoptosis. We found that PSY ethanol extract (EtOH-Ex), but not water extract, significantly suppressed the viability of human CRC cells, and synergistically decreased the cell proliferation compared to each treatment of Patriniae Radix and Coix Seed extract (PY) or Mori Cortex Radicis extract (S), suggesting the combination of PY and S in a 10-to-3 ratio for the formula PSY. PSY EtOH-Ex in the combination ratio reduced cell viability but induced cell cycle arrest at the G(2)/M and sub-G(1) phases as well as apoptosis in CRC cells. In addition, the experimental results of Western blotting, immunofluorescence staining and reporter assays showed that PSY also inhibited STAT3 by reducing its phosphorylation and nuclear localization, which resulted in lowering STAT3-mediated transcriptional activation. In addition, PSY regulated upstream signaling molecules of STAT3 by inactivating JAK2 and Src and increasing SHP1. Moreover, the chemical profiles of PSY from UPLC-ESI-QTOF MS/MS analysis revealed 38 phytochemicals, including seven organic acids, eight iridoids, two lignans, twelve prenylflavonoids, eight fatty acids, and one carbohydrate. Furthermore, 21 potentially bioactive compounds were highly enriched in the PSY EtOH-Ex compared to the water extract. Together, these results indicate that PSY suppresses the proliferation of CRC cells by inhibiting the STAT3 signaling pathway, suggesting PSY as a potential therapeutic agent for treating CRC and 21 EtOH-Ex-enriched phytochemicals as anti-cancer drug candidates which may act by inhibiting STAT3.