Physalin A, 13,14-Seco-16, 24-Cyclo-Steroid, Inhibits Stemness of Breast Cancer Cells by Regulation of Hedgehog Signaling Pathway and Yes-Associated Protein 1 (YAP1)

Abstract

The Hedgehog (HH) signaling pathway plays an important role in embryonic development and adult organ homeostasis. Aberrant activity of the Hedgehog signaling pathway induces many developmental disorders and cancers. Recent studies have investigated the relationship of this pathway with various cancers. GPCR-like protein Smoothened (SMO) and the glioma-associated oncogene (GLI1) are the main effectors of Hedgehog signaling. Physalin A, a bioactive substance derived from Physalis alkekengi, inhibits proliferation and migration of breast cancer cells and mammospheres formation. Physalin A-induced apoptosis and growth inhibition of mammospheres, and reduced transcripts of cancer stem cell (CSC) marker genes. Physalin A reduced protein expressions of SMO and GLI1/2. Down-regulation of SMO and GLI1 using siRNA inhibited mammosphere formation. Physalin A reduced mammosphere formation by reducing GLI1 gene expression. Down-regulation of GLI1 reduced CSC marker genes. Physalin A reduced protein level of YAP1. Down-regulation of YAP1 using siRNA inhibited mammosphere formation. Physalin A reduced mammosphere formation through reduction of YAP1 gene expression. Down-regulation of YAP1 reduced CSC marker genes. We showed that treatment of MDA-MB-231 breast cancer cells with GLI1 siRNA induced inhibition of mammosphere formation and down-regulation of YAP1, a Hippo pathway effector. These results show that Hippo signaling is regulated by the Hedgehog signaling pathway. Physalin A also inhibits the canonical Hedgehog and Hippo signaling pathways, CSC-specific genes, and the formation of mammospheres. These findings suggest that physalin A is a potential therapeutic agent for targeting CSCs.

Therapeutic Applications of Physalins: Powerful Natural Weapons

“…Physalins B and F are potent inhibitors of GLI-1 among PANC1 (pancreatic cancer) cells ( Hosoya et al, 2008 ; Peukert and Miller-Mosilin, 2010 ), possibly by a mechanism associated with the inhibition of Hedgehog proteins, thus causing the interruption of the binding of GLIs to DNA (effector of Hedgehog signaling) ( Jiang and Hui, 2008 ). Ko et al (2021) found similar findings with physalin A in in vitro models of breast cancer, observing the inhibition of cancer cell proliferation/migration and mammosphere formation, associated with reduced expression of SMO and GLI1/2 proteins.…”

Signaling pathways in the regulation of cancer stem cells and associated targeted therapy

“…A recent study showed that GLI1 inhibition reduced mammosphere formation of breast cancer cells. Interestingly, GLI1 inhibition resulted in a decrease in expression of YAP1, a Hippo pathway effector, suggesting a regulation activity of HH signaling on the Hippo pathway 148 …”

“…Interestingly, GLI1 inhibition resulted in a decrease in expression of YAP1, a Hippo pathway effector, suggesting a regulation activity of HH signaling on the Hippo pathway. 148 …”

“…Interestingly, GLI1 inhibition resulted in a decrease in expression of YAP1, a Hippo pathway effector, suggesting a regulation activity of HH signaling on the Hippo pathway. 148 The development of treatment resistance to cancer requires the functional support of CSC-related HH sig-naling. GLI-1 regulates oncogenesis and therapeutic resistance of colon rectal cancer, 149 with significantly higher GLI-1 expression observed in 5-FU resistant CRC cells than in nonresistant cells.…”

Fate decisions of breast cancer stem cells in cancer progression

“…FAK can regulate YAP/TAZ activation (163). Aberrant regulation of signaling pathways, such as ERa, Notch and Hedgehog, can lead to abnormal activation of Hippo, resulting in BCSC fate perturbations (164)(165)(166). The cumulative effect of aberrant regulation of these pathways in breast cancer maintains and enhances the characteristics of BCSCs, ultimately culminating in malignant tumor progression.…”