The Hedgehog (Hh) pathway is a signaling cascade that plays a crucial role in many fundamental processes, including embryonic development and tissue homeostasis. Moreover, emerging evidence has suggested that aberrant activation of Hh is associated with neoplastic transformations, malignant tumors, and drug resistance of a multitude of cancers. At the molecular level, it has been shown that Hh signaling drives the progression of cancers by regulating cancer cell proliferation, malignancy, metastasis, and the expansion of cancer stem cells (CSCs). Thus, a comprehensive understanding of Hh signaling during tumorigenesis and development of chemoresistance is necessary in order to identify potential therapeutic strategies to target various human cancers and their relapse. In this review, we discuss the molecular basis of the Hh signaling pathway and its abnormal activation in several types of human cancers. We also highlight the clinical development of Hh signaling inhibitors for cancer therapy as well as CSC-targeted therapy.

Background: Cancer stem cells (CSCs) have been proposed as central drivers of cancer relapse in many cancers. In the present study, we investigated the inhibitory effect of 20(R)-Ginsenoside Rg3 (Rg3R), a major active component of ginseng saponin, on CSC-like cells and the Epithelial-Mesenchymal Transition (EMT) in colorectal cancer (CRC). Methods: The effects of ginsenoside Rg3R on the colony-forming, migration, invasion, and wound-healing abilities of CRC cells were determined in HT29 and SW620 cell lines in vitro. Further, ginsenoside Rg3R was given intraperitoneally at 5mg/kg of mouse body weight to check its effect on the metastasis of CRC cells in vivo. Results: Ginsenoside Rg3R significantly inhibited CSC properties, but did not affect cell proliferation. Moreover, ginsenoside Rg3R treatment significantly inhibited the motility of CRC cells based on migration, invasion, and wound-healing assays. The inhibitory effects of ginsenoside Rg3R on CRC are potentially mediated by significant down-regulation of the expression of stemness genes and EMT markers in CRC cells in a SNAIL-dependent manner. Furthermore, ginsenoside Rg3R treatment decreased both the number and size of tumor nodules in the liver, lung, and kidney tissues in a metastasis mouse model. Conclusion: These findings highlighted the potential use of ginsenoside Rg3R in clinical applications for colorectal cancer treatment.

Our current understanding of the role of microRNA 551b (miR551b) in the progression of colorectal cancer (CRC) remains limited. Here, studies using both ectopic expression of miR551b and miR551b mimics revealed that miR551b exerts a tumor suppressive effect in CRC cells. Specifically, miR551b was significantly downregulated in both patient-derived CRC tissues and CRC cell lines compared to normal tissues and non-cancer cell lines. Also, miR551b significantly inhibited the motility of CRC cells in vitro, including migration, invasion, and wound healing rates, but did not affect cell proliferation. Mechanistically, miR551b targets and inhibits the expression of ZEB1 (Zinc finger E-box-binding homeobox 1), resulting in the dysregulation of EMT (epithelial-mesenchymal transition) signatures. More importantly, miR551b overexpression was found to reduce the tumor size in a xenograft model of CRC cells in vivo. Furthermore, bioinformatic analyses showed that miR551b expression levels were markedly downregulated in the advanced-stage CRC tissues compared to normal tissues, and ZEB1 was associated with the disease progression in CRC patients. Our findings indicated that miR551b could serve as a potential diagnostic biomarker and could be utilized to improve the therapeutic outcomes of CRC patients.

Hepatocellular carcinoma (HCC) exhibits diverse aetiologies and molecular heterogeneity, with a median 5-year overall survival of <70% due to high recurrence rates following curative-intent surgery. This study investigated the complex tumour microenvironment (TME) in HCC and explored interactions between various cell types and their roles in disease recurrence. Using a multi-omics approach on multi-region samples of surgically resected HCC from the PLANet 1.0 cohort (NCT03267641), we performed spatial transcriptomics on 17 tissue samples from four patients and bulk RNA sequencing on 329 sectors from 90 patients. Findings were validated using immunofluorescence and multiplex immunohistochemistry. Our analysis revealed extensive intra- and intertumour gene expression heterogeneity and identified a specific subset of endothelial cells (ECs), INTS6⁺ ECs, enriched and spatially colocalised with tumour cells in primary tumours from patients with recurrence (p = 0.021, n = 49). A significant ANGPTL4-SDC1 ligand-receptor interaction was identified between INTS6⁺ ECs and tumour cells. Notably, INTS6⁺ ECs were enriched in microvascular invasion regions and spatially colocalised with tumour cells in patients with recurrence (p = 0.036, n = 53). These findings highlight endothelial-tumour cell interactions within the TME as potential therapeutic targets. INTS6⁺ ECs are enriched in microvascular invasion regions and spatially colocalised with tumour cells in recurrent HCC, suggesting a potential role in disease recurrence and representing a promising therapeutic target within the TME. The spatial co-localisation of cell types plays a significant role in the recurrence of hepatocellular carcinoma. In this study, we have pinpointed a particular group of endothelial cells, known as INTS6+ endothelial cells, which are spatially colocalised with tumour cells and enriched in microvascular invasion regions in patients experiencing recurrence. These discoveries highlight novel therapeutic targets that focus on endothelial cell interactions within the tumour microenvironment to prevent recurrence and enhance overall patient survival.