Study on the Mechanism of <i>Phellinus linteus</i> Extract Slowing Down Breast Cancer by Regulating Cdc42/N-WASP Signaling Pathway

Background Cell division control protein 42 homolog (Cdc42)/neuronal Wiskott–Aldrich Syndrome Protein (N-WASP) is involved in a variety of tumors; however, its regulatory mechanism in breast cancer is unclear. Objectives We aimed to explore the expression and role of Phellinus linteus extract in breast cancer and its possible molecular mechanism. Materials and Methods Cdc42/N-WASP level was measured in breast cancer tissues and adjacent tissues to explore the relationship between Cdc42/N-WASP expression and clinical relevance. P. linteus extract’s role in downstream signals in breast cancer was studied through immunofluorescence assays. At the same time, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Transwell assays were used to detect the biological behaviors of cells after transfection. Results P. linteus extract can significantly reduce the biological behaviors of breast cancer cells, mainly by inhibiting cell proliferation and migration. P. linteus extract further inhibited breast cancer cell biological behaviors by inhibiting downstream Cdc42/N-WASP signaling. Moreover, Cdc42/N-WASP negatively regulated cell invasion and inhibited the degradation of extracellular matrix in breast cancer cells by regulating cortactin (CTTN). Conclusion Our results showed that P. linteus extract targets Cdc42/N-WASP and inhibits invasion and formation in breast cancer by regulating CTTN.