Objective. To investigate the regulatory effect of ZEB1 on PD-L1 expression and the pharmacodynamic effects of Biochanin A on the malignant biological behaviors of colorectal cancer (CRC). Methods. The correlation between epithelial-mesenchymal transition (EMT) score and features of the tumor microenvironment (TME) was investigated using the Cancer Genome Atlas (TCGA) dataset. The correlation between ZEB1 and PD-L1 expression was validated using immunohistochemistry (IHC) staining, and the regulatory effect of ZEB1 on PD-L1 expression was explored by in vitro assays. Moreover, the pharmacodynamic effects of Biochanin A on ZEB1 and PD-L1 expression, as well as malignant biological behaviors of CRC cells, were evaluated by in vitro and in vivo assays. Results. EMT score was positively correlated with a majority of immunostimulators, immune checkpoints, activities of antitumor immunity cycles, and infiltration levels of most immune cells in the TCGA dataset. In addition, ZEB1 was correlated with and positively regulated PD-L1 expression in CRC. Besides, Biochanin A, an inhibitor for the ZEB1/PD-L1 axis, notably inhibited ZEB1-mediated aggressiveness and PD-L1 expression of CRC cells. Moreover, Biochanin A also exerted a tumor-inhibitory role in vivo in the CRC mouse model. Conclusion. Overall, we found that ZEB1 is a main regulator of PD-L1 expression in CRC. In addition, we also identified Biochanin A as a novel inhibitor for the ZEB1/PD-L1 axis, which could inhibit tumor progression and immune escape.

Dear EditorDisheveled-associated activator of morphogenesis 1 (DAAM1) is a member of Formin protein family, which binds to the growing barbed ends and mediates microfilament polymerization during the formation of cell pseudopodia. 1 DAAM1 is evolutionarily conserved and contains two highly homologous domains, Formin homology domains 1 and 2 (FH1 and FH2). 2 Emerging evidence has uncovered that DAAM1 functions as a critical oncogene in facilitating tumor metastasis of multiple cancers. Our previous research revealed that DAAM1 was highly expressed in breast cancer tissues and was mediated by YWHAZ protein, and the cooperation between YWHAZ and DAAM1 contributed to breast cancer metastasis. 3 In addition, DAAM1 was also essential for metastasis and invasion of lung cancer. 4 However, the systematic analysis of the role of DAAM1 in pan-cancer has not been observed. In the current research, we analyzed the expressions and prognostic values of DAAM1 across cancer types and focused on the immuno-correlation of DAAM1 in kidney renal clear cell carcinoma (KIRC).Firstly, we explored the levels of DAAM1 mRNA expression in multiple tumor types using the RNA-sequencing data from The Cancer Genome Atlas (TCGA) dataset. The results showed that DAAM1 was upregulated in glioblastoma multiforme (GBM), lower grade glioma (LGG), prostate adenocarcinoma (PRAD), stomach adenocarcinoma (STAD), pancreatic adenocarcinoma (PAAD), and cholangio carcinoma (CHOL), and downregulated in uterine corpus endometrial carcinoma (UCEC), lung adenocarcinoma (LUAD), esophageal carcinoma (ESCA), kidney renal papillary cell carcinoma (KIRP), colon adenocarcinoma (COAD), KIRC, lung squamous cell carcinoma (LUSC), skin cutaneous melanoma (SKCM), bladder urothelial carcinoma (BLCA), rectum adenocarcinoma (READ), ovarian serous cystadenocarcinoma (OV), testicular germ cell tumor (TGCT), uterine carcinosarcomaThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Background: Immune checkpoint inhibitors have achieved limited clinical effectiveness in colon cancer. Stem memory T cells (TSCMs) and in-situ cytotoxic T cells are dominant contributors to host immunity. Currently, data on the correlation between TSCM and T cell abundance and clinicopathological characteristics in colon cancer are largely unavailable. Methods: In-situ cytotoxic T cells are identified based on the quantification of CD3 + and CD8 + markers using immunohistochemistry (IHC) in the core of the tumor and the invasive margin of the tumor. The expression of representative markers of TSCMs, CD27 and CD95, was assayed using IHC in colon cancer tissues. Correlations between the levels of each marker and the clinicopathological characteristics as well as prognosis were evaluated. Results: High densities of CD3 + and CD8 + T cells correlated with stage I-II tumors, whereas a lower infiltration of cytotoxic T cells correlated with advanced-stage tumors. CD27 and CD95 were both expressed in the membrane of T cells present in the tumor stroma and their levels showed a negative correlation with the TNM stage. CD3, CD8, and CD27 were expressed at the same locations simultaneously, indicating their coordinated action against cancer. In addition, cytotoxic T cell densities and CD27 and CD95 expression remained independent prognostic factors for overall survival. Conclusion:In-situ cytotoxic T cells and TSCMs play important roles in colon cancer development. TSCMs marker CD27 and CD95 were both indicators of survival in patients with colon cancer. Thus, it is believed that TSCMs represent a desirable population for future use in combination immunotherapy.