An ideal tumor treatment is supposed to eliminate the primary tumor and simultaneously trigger the host antitumor immune responses to prevent tumor recurrence and metastasis. Herein, a liposome encapsulating phosphoinositide 3-kinase gamma (PI3K ) inhibitor IPI-549 and photosensitizer chlorin e6 (Ce6), denoted by LIC, is prepared for colon cancer treatment. LIC internalized into CT26 cells generates reactive oxygen species (ROS) under laser irradiation to cause immunogenic tumor cell death, during which immunostimulatory signals such as calreticulin are released to further induce T lymphocyte-mediated tumor cell killing. Meanwhile, IPI-549 transported by liposome can inhibit PI3K in the myeloid-derived suppressive cells (MDSCs), resulting in downregulation of arginase 1 (Arg-1) and ROS to promote MDSCs apoptosis and reduce their immunosuppressive activity to CD8 + T cells. LIC-mediated immunogenic photodynamic therapy synergizes with MDSCstargeting immunotherapy, which significantly inhibits tumor growth via facilitating the dendritic cell maturation and tumor infiltration of CD8 + T cells while decreasing the tumor infiltration of immunosuppressive regulatory T cells, MDSCs, and M2-like tumor-associated macrophages. Moreover, the synergistic therapy increases the number of effector memory T cells (T EM ) in spleen, which suggests a favorable immune memory to prevent tumor recurrence and metastasis. The Ce6 and IPI-549-coloaded multifunctional nanodrug demonstrates high efficacy in colon cancer treatment.

Despite earlier studies demonstrating characteristics of colon cancer stem cells (CCSCs) and the role of epithelial-mesenchymal transition (EMT) in tumor development, it remains controversial as to the relationship between CCSCs and EMT. In this study, in order to present an insight into this relationship in colon cancer, we developed HCT116 and HT29 sphere models, which are known to be the cells enriching cancer stem cells. Compared to their parental counterparts, spheroid cells displayed lower homotypic/heterotypic adhesion but higher in vitro migratory/invasive capacity, as well as higher tumorigenic and metastatic potential in vivo. The spheroid cells also demonstrated down-regulated E-cadherin and up-regulated α-SMA and Vimentin expression, which is the typical phenotype of EMT. In order to explore whether this phenomenon is associated to activation of Wnt/β-catenin pathway, we detected several key signaling molecules. Compared with their parental cells, HCT116 and HT29 spheroid cells demonstrated down-regulated expression of GSK3β, but up-regulated expression of Slug and Snail. And also, the up-regulation of nucleus β-catenin in spheroid cells indicated that the free β-catenin transferred from cytoplasm to cell nucleus. Our findings indicate that spheroid cells have the characteristics of colon cancer stem cells, and EMT may account for their stemness and malignancy. And persistent activation of Wnt/β-catenin pathway may play an important role in the EMT of CCSCs.

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R‐spondins comprise a group of secreted WNT agonists. R‐spondin2 (RSPO2) plays a crucial role in the activation of the WNT/β‐catenin pathway and oncogenesis, though its specific role in human gastric cancer (GC) remains unclear. In the current study, RSPO2 expression levels were upregulated in cancer specimens and cell lines (AGS and BGC‐823). Inhibition of RSPO2 expression levels had distinct effects on cell invasion, migration, and epithelial‐mesenchymal transition (EMT) in AGS and BGC‐823 cells in vitro. Furthermore, RSPO2 positively correlated with leucine‐rich repeat‐containing G‐protein‐coupled receptor 5 (LGR5), the receptor of RSPO2. Silencing RSPO2 reduced the expression of LGR5 and WNT/β‐catenin effector molecule β‐catenin together with downstream targets TCF‐4 and Cyclin‐D1. These observations demonstrate that upregulation of RSPO2 in GC specimens and cell lines is closely related to tumor invasion and migration and that RSPO2 promotes EMT in gastric cancer cells by activating WNT/β‐catenin signaling.