Involvement of hedgehog pathway in early onset, aggressive molecular subtypes and metastatic potential of breast cancer

Probing the biological efficacy and mechanistic pathways of natural compounds in breast cancer therapy via the Hedgehog signaling pathway

Breast cancer (BC) is one of the most prevalent malignant tumors affecting women worldwide, with its incidence rate continuously increasing. As a result, treatment strategies for this disease have received considerable attention. Research has highlighted the crucial role of the Hedgehog (Hh) signaling pathway in the initiation and progression of BC, particularly in promoting tumor growth and metastasis. Therefore, molecular targets within this pathway represent promising opportunities for the development of novel BC therapies. This study aims to elucidate the therapeutic mechanisms by which natural compounds modulate the Hh signaling pathway in BC. By conducting a comprehensive review of various natural compounds, including polyphenols, terpenes, and alkaloids, we reveal both common and unique regulatory mechanisms that influence this pathway. This investigation represents the first comprehensive analysis of five distinct mechanisms through which natural compounds modulate key molecules within the Hh pathway and their impact on the aggressive behaviors of BC. Furthermore, by exploring the structure-activity relationships between these compounds and their molecular targets, we shed light on the specific structural features that enable natural compounds to interact with various components of the Hh pathway. These novel insights contribute to advancing the development and clinical application of natural compound-based therapeutics. Our thorough review not only lays the groundwork for exploring innovative BC treatments but also opens new avenues for leveraging natural compounds in cancer therapy.

GLI2 inhibits cisplatin sensitivity in gastric cancer through DEC1/ZEB1 mediated EMT

Cisplatin (CDDP) based chemotherapy has emerged as the predominant therapeutic regimen for patients with advanced gastric cancer (GC). However, its efficacy is dampened by the development of chemoresistance, which results in poor prognosis of patients. GLI2, a key transcription factor in the Hedgehog (Hh) signaling pathway, is regarded as a target for cancer therapy. However, the significance of GLI2 for CDDP resistance in GC has not been well established. Here, we show that GLI2 expression was upregulated in EMT-type GC and associated with poor prognosis. GLI2 promotes proliferation, migration, and CDDP resistance of GC cells by inducing EMT. In terms of mechanism, GLI2 binds to the promoter region of DEC1 and enhances its expression, thereby co-transcriptionally regulating ZEB1 expression. Animal experiments have demonstrated that both GLI2 knockdown and GLI2 inhibitor significantly enhance CDDP sensitivity in GC. Our data not only identify a novel GLI2/DEC1/ZEB1/EMT pathway in GC CDDP resistance but also provide novel strategies to treat GC in the future.

Breast Morphogenesis: From Normal Development to Cancer

The human breast gland is composed of branching epithelial ducts that culminate in milk-producing units known as terminal duct lobular units (TDLUs). The epithelial compartment comprises an inner layer of luminal epithelial cells (LEP) and an outer layer of contractile myoepithelial cells (MEP). Both LEP and MEP arise from a common stem cell population. The epithelial compartment undergoes dynamic branching morphogenesis and remodelling, which expands the surface area for milk production. The epithelial remodelling that starts at the onset of menarche is largely under hormonal control, first and foremost by estrogen and progesterone from ovaries, the production of which is stimulated by pituitary-derived hormones. Menopause leads to a significant decline in estrogen and progesterone levels, resulting in involution and senescence of the breast epithelium. The branching morphogenesis involves developmental events such as epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET). EMT and MET confer plasticity to the epithelial compartment enabling the migration of epithelial cells through the stroma and restoration of the epithelial phenotype. In the normal breast, the stroma, including the basement membrane (BM), collagen-rich extracellular matrix, and various stromal cells, supports the correct histoarchitecture of the glandular tree. However, in cancer, the stroma can acquire tumour-promoting properties and is referred to as the tumour microenvironment. This chapter will explore the developmental processes including branching morphogenesis in the normal breast gland and discuss the lineage relationship between LEPS and MEPs and their interactions with the surrounding stroma in the normal and neoplastic breast gland. Finally, we will review various in vitro and in vivo models employed in mammary gland research.

Evaluating the impact of Xanthoparmelia conspersa extracts on signaling in HeLa cells and exploring their diverse biological activities

Xanthoparmelia conspersa is rich in specific secondary metabolites but an unexplored lichen species. This work determined the chemical composition and biological activities (anti-microbial, anti-protozoal, and cytotoxic) of its methanolic and hexane extracts. Additionally, we evaluated the potential of these extracts in modulating cancer signaling pathways in HeLa cells. The phytochemical analysis revealed that usnic acid was the predominant constituent in the hexane extract, while stictic acid was in the methanolic one. Among tested cell lines (VERO, FaDu, SCC-25, HeLa), cytotoxic selectivity was detected for X. conspersa hexane extract against the FaDu (SI 7.36) and HeLa (SI 2.19) cells. A noticeably better anti-microbial potential was found for hexane extract, however, the overall anti-microbial activity was relatively weak (28, 21, and 20% inhibition of Candida glabrata, Cryptococcus neoformans, and Escherichia coli, respectively). On the contrary, the anti-parasitic action of hexane extract was significant, with an IC50 value of 2.64 µg/mL against Leishmania donovani - amastigote and 7.18 µg/mL against Trypanosoma brucei. The detailed evaluation of the cancer-related signaling pathways in HeLa cells, done by two distinct methodologies (luciferase reporter tests), revealed that especially the hexane extract and usnic acid exhibited selective inhibition of Stat3, Smad, NF-κB, cMYC, and Notch pathways.

Exploring the clinical potential of circulating LncRNAs in breast cancer: insights into primary signaling pathways and therapeutic interventions

Breast cancer (BC) occupies the top spot among women on a global scale. The tumor has a significant degree of heterogeneity, displaying a notable prevalence of medication resistance, recurrence, and metastasis, rendering it one of the most lethal forms of malignant neoplasms. The timely identification, ongoing evaluation of therapeutic interventions, and accurate prediction of outcomes play crucial roles in determining the overall survival rates of women with BC. Nevertheless, the absence of precise biomarkers remains a significant determinant impacting the overall well-being and both the physical and emotional health of BC patients. Long noncoding RNA (lncRNA) exerts regulatory control over several genes and signaling pathways, hence assuming crucial roles in the development of neoplastic growth. Recently, research has indicated that the atypical expression of circulating lncRNAs in various biological bodily fluids has a noteworthy impact on the early detection, pathological categorization, staging, monitoring of therapy outcomes, and evaluation of prognosis in cases of BC. This article aims to assess the potential clinical utility of circulating lncRNAs in the context of BC focusing on specific primary signaling pathways; Wnt/β-catenin, Notch, TGF-β, and hedgehog (Hh), in addition to some therapeutic interventions.

Breast Cancer Stem Cells and Tumor Heterogeneity: Characteristics and Therapeutic Strategies

Breast cancer is one of the most frequently detected malignancies worldwide. It is responsible for more than 15% of all death cases caused by cancer in women. Breast cancer is a heterogeneous disease representing various histological types, molecular characteristics, and clinical profiles. However, all breast cancers are organized in a hierarchy of heterogeneous cell populations, with a small proportion of cancer stem cells (breast cancer stem cells (BCSCs)) playing a putative role in cancer progression, and they are responsible for therapeutic failure. In different molecular subtypes of breast cancer, they present different characteristics, with specific marker profiles, prognoses, and treatments. Recent efforts have focused on tackling the Wnt, Notch, Hedgehog, PI3K/Akt/mTOR, and HER2 signaling pathways. Developing diagnostics and therapeutic strategies enables more efficient elimination of the tumor mass together with the stem cell population. Thus, the knowledge about appropriate therapeutic methods targeting both "normal" breast cancer cells and breast cancer stem cell subpopulations is crucial for success in cancer elimination.

Identification of Novel GANT61 Analogs with Activity in Hedgehog Functional Assays and GLI1-Dependent Cancer Cells

Aberrant activation of hedgehog (Hh) signaling has been implicated in various cancers. Current FDA-approved inhibitors target the seven-transmembrane receptor Smoothened, but resistance to these drugs has been observed. It has been proposed that a more promising strategy to target this pathway is at the GLI1 transcription factor level. GANT61 was the first small molecule identified to directly suppress GLI-mediated activity; however, its development as a potential anti-cancer agent has been hindered by its modest activity and aqueous chemical instability. Our study aimed to identify novel GLI1 inhibitors. JChem searches identified fifty-two compounds similar to GANT61 and its active metabolite, GANT61-D. We combined high-throughput cell-based assays and molecular docking to evaluate these analogs. Five of the fifty-two GANT61 analogs inhibited activity in Hh-responsive C3H10T1/2 and Gli-reporter NIH3T3 cellular assays without cytotoxicity. Two of the GANT61 analogs, BAS 07019774 and Z27610715, reduced Gli1 mRNA expression in C3H10T1/2 cells. Treatment with BAS 07019774 significantly reduced cell viability in Hh-dependent glioblastoma and lung cancer cell lines. Molecular docking indicated that BAS 07019774 is predicted to bind to the ZF4 region of GLI1, potentially interfering with its ability to bind DNA. Our findings show promise in developing more effective and potent GLI inhibitors.

Therapeutic potential of hedgehog signaling in advanced cancer types

In this chapter, we have made an attempt to elucidate the relevance of hedgehog signaling pathway in tumorigenesis. Here, we have described different types of hedgehog signaling (canonical and non-canonical) with emphasis on the different mechanisms (mutation-driven, autocrine, paracrine and reverse paracrine) it adopts during tumorigenesis. We have discussed the role of hedgehog signaling in regulating cell proliferation, invasion and epithelial-to-mesenchymal transition in both local and advanced cancer types, as reported in different studies based on preclinical and clinical models. We have specifically addressed the role of hedgehog signaling in aggressive neuroendocrine tumors as well. We have also elaborated on the studies showing therapeutic relevance of the inhibitors of hedgehog signaling in cancer. Evidence of the crosstalk of hedgehog signaling components with other signaling pathways and treatment resistance due to tumor heterogeneity have also been briefly discussed. Together, we have tried to put forward a compilation of the studies on therapeutic potential of hedgehog signaling in various cancers, specifically aggressive tumor types with a perspective into what is lacking and demands further investigation.

Targeting breast cancer stem cells through retinoids: A new hope for treatment

Breast cancer is a complex and diverse disease accounting for nearly 30% of all cancers diagnosed in females. But unfortunately, patients develop resistance to the existing chemotherapeutic regimen, resulting in approximately 90% treatment failure. With over half a million deaths annually, it is imperative to explore new therapeutic approaches to combat the disease. Within a breast tumor, a small sub-population of heterogeneous cells, with a unique ability of self-renew and differentiation and responsible for tumor formation, initiation, and recurrence are referred to as breast cancer stem cells (BCSCs). These BCSCs have been identified as one of the main contributors to chemoresistance in breast cancer, making them an attractive target for developing novel therapeutic strategies. These cells exhibit surface biomarkers such as CD44+, CD24-/LOW, ALDH, CD133, and CD49f phenotypes. Higher expression of CD44+ and ALDH activity has been associated with the formation of tumors in various cancers. Moreover, the abnormal regulation of signaling pathways, including Hedgehog, Notch, β-catenin, JAK/STAT, and P13K/AKT/mTOR, leads to the formation of cancer stem cells, resulting in the development of tumors. The growing drug resistance in BC is a significant challenge, highlighting the need for new therapeutic strategies to combat this dreadful disease. Retinoids, a large group of synthetic derivatives of vitamin A, have been studied as chemopreventive agents in clinical trials and have been shown to regulate various crucial biological functions including vision, development, inflammation, and metabolism. On a cellular level, the retinoid activity has been well characterized and translated and is known to induce differentiation and apoptosis, which play important roles in the outcome of the transformation of tissues into malignant. Retinoids have been investigated extensively for their use in the treatment and prevention of cancer due to their high receptor-binding affinity to directly modulate gene expression programs. Therefore, in this study, we aim to summarize the current understanding of BCSCs, their biomarkers, and the associated signaling pathways. Retinoids, such as Adapalene, a third-generation retinoid, have shown promising anti-cancer potential and may serve as therapeutic agents to target BCSCs.

Hedgehog signaling in tissue homeostasis, cancers, and targeted therapies

The past decade has seen significant advances in our understanding of Hedgehog (HH) signaling pathway in various biological events. HH signaling pathway exerts its biological effects through a complex signaling cascade involved with primary cilium. HH signaling pathway has important functions in embryonic development and tissue homeostasis. It plays a central role in the regulation of the proliferation and differentiation of adult stem cells. Importantly, it has become increasingly clear that HH signaling pathway is associated with increased cancer prevalence, malignant progression, poor prognosis and even increased mortality. Understanding the integrative nature of HH signaling pathway has opened up the potential for new therapeutic targets for cancer. A variety of drugs have been developed, including small molecule inhibitors, natural compounds, and long non-coding RNA (LncRNA), some of which are approved for clinical use. This review outlines recent discoveries of HH signaling in tissue homeostasis and cancer and discusses how these advances are paving the way for the development of new biologically based therapies for cancer. Furthermore, we address status quo and limitations of targeted therapies of HH signaling pathway. Insights from this review will help readers understand the function of HH signaling in homeostasis and cancer, as well as opportunities and challenges of therapeutic targets for cancer.

Cancer invasion and metastasis: Insights from murine pubertal mammary gland morphogenesis

Cancer invasion and metastasis accounts for the majority of cancer related mortality. A better understanding of the players that drive the aberrant invasion and migration of tumors cells will provide critical targets to inhibit metastasis. Postnatal pubertal mammary gland morphogenesis is characterized by highly proliferative, invasive, and migratory normal epithelial cells. Identifying the molecular regulators of pubertal gland development is a promising strategy since tumorigenesis and metastasis is postulated to be a consequence of aberrant reactivation of developmental stages. In this review, we summarize the pubertal morphogenesis regulators that are involved in cancer metastasis and revisit pubertal mammary gland transcriptome profiling to uncover both known and unknown metastasis genes. Our updated list of pubertal morphogenesis regulators shows that most are implicated in invasion and metastasis. This review highlights molecular linkages between development and metastasis and provides a guide for exploring novel metastatic drivers.

Deciphering Common Traits of Breast and Ovarian Cancer Stem Cells and Possible Therapeutic Approaches

Breast cancer (BC) and ovarian cancer (OC) are among the most common and deadly cancers affecting women worldwide. Both are complex diseases with marked heterogeneity. Despite the induction of screening programs that increase the frequency of earlier diagnosis of BC, at a stage when the cancer is more likely to respond to therapy, which does not exist for OC, more than 50% of both cancers are diagnosed at an advanced stage. Initial therapy can put the cancer into remission. However, recurrences occur frequently in both BC and OC, which are highly cancer-subtype dependent. Therapy resistance is mainly attributed to a rare subpopulation of cells, named cancer stem cells (CSC) or tumor-initiating cells, as they are capable of self-renewal, tumor initiation, and regrowth of tumor bulk. In this review, we will discuss the distinctive markers and signaling pathways that characterize CSC, their interactions with the tumor microenvironment, and the strategies they employ to evade immune surveillance. Our focus will be on identifying the common features of breast cancer stem cells (BCSC) and ovarian cancer stem cells (OCSC) and suggesting potential therapeutic approaches.

Activation of the hedgehog signaling pathway is associated with the promotion of cell proliferation and epithelial-mesenchymal transition in chronic rhinosinusitis with nasal polyps

PURPOSE

To investigate the pathogenesis of the hedgehog (Hh) signaling pathway activated by inflammation in the development of chronic rhinosinusitis with nasal polyps (CRSwNP).

METHODS

The 82 people including CRSwNP patients (case group) and nasal septal deviation patients (control group) were recruited. The samples in the case group were collected and classified into two groups: mucosal tissue of nasal polyps (NP group) and mucosal tissue adjacent to nasal polyps (NM group), the samples were collected from the control group as CM group. Clinical characteristics were assessed. Hematoxylin and eosin (H&E) and immunohistochemical (IHC) staining were performed to detect eosinophils (EOS), the expression of the key genes of the pathway and epithelial-mesenchymal transition (EMT) markers in the samples.

RESULTS

There were significant differences in the nasal obstruction visual analog scale (VAS) score, rhinorrhea VAS score, percentage of blood EOS, blood EOS absolute counts and tissue EOS counts in the case group compared with the control group (P < 0.05). The EOS level and expression levels of PTCH1, SMO, Gli1, Gli2, Ki67 and vimentin were higher in NP group than in the other two groups (P < 0.05). E-cadherin expression was decreased in NP group (P < 0.05). A positive correlation between PTCH1 expression and CRSwNP Lund-Mackay score in NP group.

CONCLUSIONS

Our results indicated that the activation of Hh signaling pathway might promote cell proliferation and EMT occurrence, ultimately leading to the development of CRSwNP, which might provide a new target for treatment.

Using publicly available datasets to identify population-based transcriptomic landscape contributing to the aggressiveness of breast cancer in young women

Introduction: Although the risk of breast cancer increases with advancing age, some regions have larger number of young breast cancer patients (≤45 years-old), such as the Middle East, Eastern Asia, and North Africa, with more aggressive and poorly differentiated tumors. We aimed to conduct an in-silico analysis in an attempt to understand the aggressive nature of early-onset breast cancer, and to identify potential drivers of early-onset breast cancer using gene expression profiling datasets in a population-dependent manner. Methods: Functional genomics experiments data were acquired from cBioPortal database for cancer genomics, followed by the stratification of patients based on the age at representation of breast cancer and race. Differential gene expression analysis and gene amplification status analysis were carried out, followed by hub gene, transcription factor, and signalling pathway identification. Results: PAM50 subtype analysis revealed that young patients (≤45 years-old) had four-fold more basal tumors and worst progression-free survival (median of 101 months), compared with the 45-65 years group (median of 168 months). Fourteen genes were amplified in more than 14% of patients with an early-onset breast cancer. Interestingly, FREM2, LINC00332, and LINC00366 were exclusively amplified in younger patients. Gene expression data from three different populations (Asian, White, and African) revealed a unique transcriptomic profile of young patients, which was also reflected on the PAM50 subtype analysis. Our data indicates a higher tendency of young African patients to develop basal tumors, while young Asian patients are more prone to developing Luminal A tumors. Most genes that were found to be upregulated in younger patients are involved in important signaling pathways that promote cancer progression and metastasis, such as MAPK pathway, Reelin pathway and the PI3K/Akt pathway. Conclusion: This study provides strong evidence that the molecular profile of tumors derived from young breast cancer patients of different populations is unique and may explain the aggressiveness of these tumors, stressing the need to conduct population- based multi-omic analyses to identify the potential drivers for tumorigenesis and molecular profiles of young breast cancer patients.

Synergistic effect of CD47 blockade in combination with cordycepin treatment against cancer

Cordycepin is widely considered a direct tumor-suppressive agent. However, few studies have investigated as the effect of cordycepin therapy on the tumor microenvironment (TME). In our present study, we demonstrated that cordycepin could weaken the function of M1-like macrophages in the TME and also contribute to macrophage polarization toward the M2 phenotype. Herein, we established a combined therapeutic strategy combining cordycepin and an anti-CD47 antibody. By using single-cell RNA sequencing (scRNA-seq), we showed that the combination treatment could significantly enhance the effect of cordycepin, which would reactivate macrophages and reverse macrophage polarization. In addition, the combination treatment could regulate the proportion of CD8⁺ T cells to prolong the progression-free survival (PFS) of patients with digestive tract malignancies. Finally, flow cytometry validated the changes in the proportions of tumor-associated macrophages (TAMs) and tumor-infiltrating lymphocytes (TILs). Collectively, our findings suggested that the combination treatment of cordycepin and the anti-CD47 antibody could significantly enhance tumor suppression, increase the proportion of M1 macrophages, and decrease the proportion of M2 macrophages. In addition, the PFS in patients with digestive tract malignancies would be prolonged by regulating CD8 ⁺ T cells.

GLIS2 and CCND1 expression levels in breast cancer patients

BACKGROUND

Breast cancer (BC) is the most prevalent cancer in women, with increasing incidence and death rates in recent years. Disruptions of different signaling pathways partially cause breast cancer. Hence, different genes through particular pathways are involved in BC tumorigenesis.

METHODS

In this study, we evaluated the expression level of GLIS2 and CCND1 genes in 50 patients. Also, in-silico analyses were used to enrich related signaling pathways involving the mentioned genes.

RESULTS

The results showed an increased expression level of Cyclin D1 and decreased expression level of GLIS2 in BC patients. Moreover, a relationship between aberrant expression levels of GLIS2 and CCND1 and BC development was determined.

CONCLUSION

These observations could help uncover new therapeutic targets for treating patients with BC in the progressive stage.

Higher Expressions of SHH and AR Are Associated with a Positive Receptor Status and Have Impact on Survival in a Cohort of Croatian Breast Cancer Patients

Breast cancers (BC) are usually classified into four molecular subtypes according to the expression of estrogen (ER), progesterone (PR), and human epidermal growth factor 2 (HER2) receptors and proliferation marker Ki-67. Despite available anti-hormonal therapies and due to the inherent propensity of some subtypes to develop metastasis, there is a permanent need to discover new prognostic and predictive biomarkers, as well as therapeutic targets for BC. In this study, we used immunohistochemical staining to determine the expression of androgen receptor (AR) and sonic hedgehog protein (SHH), the main ligand of the Hedgehog-GLI (HH-GLI) signaling pathway, in 185 archival primary BC tissue samples and correlated it with clinicopathological characteristics, molecular subtypes, receptors statuses, and survival in a cohort of Croatian BC patients. Results showed that higher SHH and AR expressions were associated with positive receptor status, but increased SHH expression had a negative impact on survival in receptor-negative BCs. On the contrary, higher AR expression was mostly protective. However, multivariate analysis showed that only higher AR expression could be considered as an independent prognostic biomarker for poorer overall survival in triple-negative breast cancer patients (TNBC) (HR 10.9, 95% CI 1.43-83.67; p = 0.021), what could be Croatian population-related. SHH could be a potential target for treating TNBCs and HER2-enriched BCs, in cases where HH-GLI signaling is canonical (SHH-dependent).

Breast cancer: molecular mechanisms of underlying resistance and therapeutic approaches

Breast cancer (BC) affects over 250,000 women in the US each year. Drug-resistant cancer cells are responsible for most breast cancer fatalities. Scientists are developing novel chemotherapeutic drugs and targeted therapy combinations to overcome cancer cell resistance. Combining drugs can reduce the chances of a tumor developing resistance to treatment. Clinical research has shown that combination chemotherapy enhances or improves survival, depending on the patient's response to treatment. Combination therapy is a highly successful supplemental cancer treatment. This review sheds light on intrinsic resistance to BC drugs and the importance of combination therapy for BC treatment. In addition to recurrence and metastasis of BC, the article discussed biomarkers for BC.

Expression of HK2, PKM2, and PFKM Is Associated with Metastasis and Late Disease Onset in Breast Cancer Patients

The reprogramming of energy metabolism is one of the hallmarks of cancer and is crucial for tumor progression. Altered aerobic glycolysis is a well-known characteristic of cancer cell metabolism. In the present study, the expression profiles of key metabolic genes (HK2, PFKM, and PKM2) were assessed in the breast cancer cohort of Pakistan using quantitative polymerase chain reaction (qPCR) and IHC. Expression patterns were correlated with molecular subtypes and clinical parameters in the patients. A significant upregulation of key glycolytic genes was observed in tumor samples in comparison to their adjacent controls (p < 0.0001). The expression of the studied glycolytic genes was significantly increased in late clinical stages, positive nodal involvement, and distant metastasis (p < 0.05). HK2 and PKM2 were found to be upregulated in luminal B, whereas PFKM was overexpressed in the luminal A subtype of breast cancer. The genes were positively correlated with the proliferation marker Ki67 (p < 0.001). Moreover, moderate positive linear correlations between HK2 and PKM2 (r = 0.476), HK2 and PFKM (r = 0.473), and PKM2 and PFKM (r = 0.501) were also observed (p < 0.01). These findings validate that the key regulatory genes in glycolysis can serve as potential biomarkers and/or molecular targets for breast cancer management. However, the clinical significance of these molecules needs to be further validated through in vitro and in vivo experiments.

Novel Pathways for Targeting Tumor Angiogenesis in Metastatic Breast Cancer

Breast cancer is the most common cancer affecting women and is the second leading cause of cancer related death worldwide. Angiogenesis, the process of new blood vessel development from pre-existing vasculature, has been implicated in the growth, progression, and metastasis of cancer. Tumor angiogenesis has been explored as a key therapeutic target for decades, as the blockade of this process holds the potential to reduce the oxygen and nutrient supplies that are required for tumor growth. However, many existing anti-angiogenic approaches, such as those targeting Vascular Endothelial Growth Factor, Notch, and Angiopoietin signaling, have been associated with severe side-effects, limited survival advantage, and enhanced cancer regrowth rates. To address these setbacks, alternative pathways involved in the regulation of tumor angiogenesis are being explored, including those involving Bone Morphogenetic Protein-9 signaling, the Sonic Hedgehog pathway, Cyclooxygenase-2, p38-mitogen-activated protein kinase, and Chemokine Ligand 18. This review article will introduce the concept of tumor angiogenesis in the context of breast cancer, followed by an overview of current anti-angiogenic therapies, associated resistance mechanisms and novel therapeutic targets.

Concomitant activation of GLI1 and Notch1 contributes to racial disparity of human triple negative breast cancer progression

Mortality from triple negative breast cancer (TNBC) is significantly higher in African American (AA) women compared to White American (WA) women emphasizing ethnicity as a major risk factor; however, the molecular determinants that drive aggressive progression of AA-TNBC remain elusive. Here, we demonstrate for the first time that AA-TNBC cells are inherently aggressive, exhibiting elevated growth, migration, and cancer stem-like phenotype compared to WA-TNBC cells. Meta-analysis of RNA-sequencing data of multiple AA- and WA-TNBC cell lines shows enrichment of GLI1 and Notch1 pathways in AA-TNBC cells. Enrichment of GLI1 and Notch1 pathway genes was observed in AA-TNBC. In line with this observation, analysis of TCGA dataset reveals a positive correlation between GLI1 and Notch1 in AA-TNBC and a negative correlation in WA-TNBC. Increased nuclear localization and interaction between GLI1 and Notch1 is observed in AA-TNBC cells. Of importance, inhibition of GLI1 and Notch1 synergistically improves the efficacy of chemotherapy in AA-TNBC cells. Combined treatment of AA-TNBC-derived tumors with GANT61, DAPT, and doxorubicin/carboplatin results in significant tumor regression, and tumor-dissociated cells show mitigated migration, invasion, mammosphere formation, and CD44⁺/CD24^- population. Indeed, secondary tumors derived from triple-therapy-treated AA-TNBC tumors show diminished stem-like phenotype. Finally, we show that TNBC tumors from AA women express significantly higher level of GLI1 and Notch1 expression in comparison to TNBC tumors from WA women. This work sheds light on the racial disparity in TNBC, implicates the GLI1 and Notch1 axis as its functional mediators, and proposes a triple-combination therapy that can prove beneficial for AA-TNBC.

Hedgehog Pathway Inhibitors against Tumor Microenvironment

Targeting the hedgehog (HH) pathway to treat aggressive cancers of the brain, breast, pancreas, and prostate has been ongoing for decades. Gli gene amplifications have been long discovered within malignant glioma patients, and since then, inhibitors against HH pathway-associated molecules have successfully reached the clinical stage where several of them have been approved by the FDA. Albeit this success rate implies suitable progress, clinically used HH pathway inhibitors fail to treat patients with metastatic or recurrent disease. This is mainly due to heterogeneous tumor cells that have acquired resistance to the inhibitors along with the obstacle of effectively targeting the tumor microenvironment (TME). Severe side effects such as hyponatremia, diarrhea, fatigue, amenorrhea, nausea, hair loss, abnormal taste, and weight loss have also been reported. Furthermore, HH signaling is known to be involved in the regulation of immune cell maturation, angiogenesis, inflammation, and polarization of macrophages and myeloid-derived suppressor cells. It is critical to determine key mechanisms that can be targeted at different levels of tumor development and progression to address various clinical issues. Hence current research focus encompasses understanding how HH controls TME to develop TME altering and combinatorial targeting strategies. In this review, we aim to discuss the pros and cons of targeting HH signaling molecules, understand the mechanism involved in treatment resistance, reveal the role of the HH pathway in anti-tumor immune response, and explore the development of potential combination treatment of immune checkpoint inhibitors with HH pathway inhibitors to target HH-driven cancers.

Targeted Inhibition of Fibroblast Growth Factor Receptor 1-GLI Through AZD4547 and GANT61 Modulates Breast Cancer Progression

The underlying mechanism of fibroblast growth factor receptor 1 (FGFR1) mediated carcinogenesis is still not fully understood. For instance, FGFR1 upregulation leads to endocrine therapy resistance in breast cancer patients. The current study aimed to identify FGFR1-linked genes to devise improved therapeutic strategies. RNA-seq and microarray expression data of 1,425 breast cancer patients from two independent cohorts were downloaded for the analysis. Gene Set Enrichment Analysis (GSEA) was performed to identify differentially expressed pathways associated with FGFR1 expression. Validation was done using 150 fresh tumor biopsy samples of breast cancer patients. The clinical relevance of mRNA and protein expression of FGFR1 and its associated genes were also evaluated in mouse embryonic fibroblasts (MEFs) and breast cancer cell line (MDA-MB-231). Furthermore, MDA-MB-231 cell line was treated with AZD4547 and GANT61 to identify the probable role of FGFR1 and its associated genes on cells motility and invasion. According to GSEA results, SHH pathway genes were significantly upregulated in FGFR1 patients in both discovery cohorts of breast cancer. Statistical analyses using both discovery cohorts and 150 fresh biopsy samples revealed strong association of FGFR1 and GLI1, a member of SHH pathway. The increase in the expression of these molecules was associated with poor prognosis, lymph node involvement, late stage, and metastasis. Combined exposures to AZD4547 (FGFR1 inhibitor) and GANT61 (GLI1 inhibitor) significantly reduced cell proliferation, cell motility, and invasion, suggesting molecular crosstalk in breast cancer progression and metastasis. A strong positive feedback mechanism between FGFR1-GLI1 axis was observed, which significantly increased cell proliferation and metastasis. Targeting FGFR1-GLI1 simultaneously will significantly improve the prognosis of breast cancer in patients.

The Role of the Hedgehog Pathway in Cholangiocarcinoma

Simple Summary

Cholangiocarcinoma (CCA) is one of the most refractory malignancies with a high mortality rate. Among all the pathways involved in CCA development, emerging evidence highlights Hedgehog (HH) signaling as a substantial player in CCA-genesis and development. The pro-tumoral function of HH provides potential therapeutic implications, and recently the use of HH inhibitors has paved the way for clinical application in various solid tumors. Targeting HH members, namely Hedgehog ligands, SMO transmembrane protein and GLI transcription factors may thus confer therapeutic options for the improvement of CCA treatment outcome.

Abstract

Cholangiocarcinoma (CCA) is a poorly treatable type of cancer and, along with hepatocellular carcinoma (HCC), is the predominant type of primitive liver cancer in adults. The lack of understanding of CCA biology has slowed down the identification of novel targets and the development of effective treatments. While tumors share some general characteristics, detailed knowledge of specific features is essential for the development of effectively tailored therapeutic approaches. The Hedgehog (HH) signaling cascade regulates stemness biology, embryonal development, tissue homeostasis, and cell proliferation and differentiation. Its aberrant activation has been associated with a variety of solid and hematological human malignancies. Several HH-inhibiting compounds have been indeed developed as potential anticancer agents in different types of tumors, with Smoothened and GLI inhibitors showing the most promising results. Beside its well-established function in other tumors, findings regarding the HH signaling in CCA are still controversial. Here we will give an overview of the most important clinical and molecular features of cholangiocarcinoma, and we will discuss the available evidence of the crosstalk between the HH signaling pathway and the cholangiocarcinoma cell biology.

Adenomatous Polyposis Coli loss controls cell cycle regulators and response to paclitaxel in MDA-MB-157 metaplastic breast cancer cells

Adenomatous Polyposis Coli (APC) is lost in approximately 70% of sporadic breast cancers, with an inclination towards triple negative breast cancer (TNBC). TNBC is treated with traditional chemotherapy, such as paclitaxel (PTX); however, tumors often develop drug resistance. We previously created APC knockdown cells (APC shRNA1) using the human TNBC cells, MDA-MB-157, and showed that APC loss induces PTX resistance. To understand the mechanisms behind APC-mediated PTX response, we performed cell cycle analysis and analyzed cell cycle related proteins. Cell cycle analysis indicated increased G2/M population in both PTX-treated APC shRNA1 and parental cells, suggesting that APC expression does not alter PTX-induced G2/M arrest. We further studied the subcellular localization of the G2/M transition proteins, cyclin B1 and CDK1. The APC shRNA1 cells had increased CDK1, which was preferentially localized to the cytoplasm, and increased baseline CDK6. RNA-sequencing was performed to gain a global understanding of changes downstream of APC loss and identified a broad mis-regulation of cell cycle-related genes in APC shRNA1 cells. Our studies are the first to show an interaction between APC and taxane response in breast cancer. The implications include designing combination therapy to re-sensitize APC-mutant breast cancers to taxanes using the specific cell cycle alterations.

Hedgehog gene expression patterns among intrinsic subtypes of breast cancer: Prognostic relevance

PURPOSE

Hedgehog (Hh) signaling is a crucial developmental regulatory pathway recognized as a primary oncogenesis driver in various human cancers. However, its role in breast carcinoma (BC) has been underexplored.

METHODS

We analyzed the expression of several Hh associated genes in a clinical series and breast cancer cell lines. We included 193 BC stratified according to intrinsic immunophenotypes. Gene expression profiling ofBOC, PTCH, SMO, GLI1, GLI2, and GLI3 was performed by qRT-PCR. Results were correlated with clinical-pathological variables and outcome.

RESULTS

We observed expression ofGLI2 in triple-negative/basal-like (TN/BL) and GLI3 in luminal cells. In samples, BOC, GLI1, GLI2, and GLI3 expression correlated significantly with luminal tumors and good prognostic factors. In contrast, PTCH and SMO correlated with TN/BL phenotype and nodal involvement. Patients whose tumors expressed SMO had a poorer outcome, especially those with HER2 phenotype. Positive lymph-node status and high SMO remained independent poor prognostic factors.

CONCLUSION

Our results support a differential Hh pathway activation in BC phenotypes.SMO levels stratified patients at risk of recurrence and death in HER2 phenotype, and it showed an independent prognostic value. Therefore, SMO could be a potential therapeutic target for a subset of BC patients.

MicroRNA-26a inhibits cell proliferation and invasion by targeting FAM98A in breast cancer

MicroRNAs (miRNAs/miRs) play key roles in cancer progression. Extensive research has revealed that miR-26a is abnormally expressed and functions as a tumor suppressor in numerous types of cancer. Thus, the present study was undertaken to investigate the regulatory role and potential mechanism of action of miR-26a in breast cancer. Furthermore, the present study aimed to examine the alterations in miR-26a expression and its effects on human breast cancer cells. Reverse transcription-quantitative PCR was conducted to assess the differences in miR-26a expression between human breast cancer and normal breast specimens. A Cell Counting Kit-8 assay and cloning experiments were used to detect cell proliferation and clone formation. Wound healing and Transwell assays were performed to examine cell migration and invasion. A luciferase activity experiment was utilized to validate the association between miR-26a and family with sequence similarity 98 member A (FAM98A). Western blotting was conducted to detect the protein expression levels of FAM98A, sonic hedgehog signaling molecule (SHH), smoothened, frizzled class receptor (SMO) and GLI family zinc finger 1 (GLI1). The results indicated that miR-26a expression was decreased in breast carcinoma tissues and cell lines. Moreover, overexpression of miR-26a significantly suppressed cell proliferation, clone formation ability and metastasis, and it sensitized breast cancer cells to docetaxel. It was demonstrated that miR-26a directly targeted FAM98A, and that FAM98A, SHH, SMO and GLI1 expression levels were decreased in cells transfected with miR-26a mimics. Collectively, the results of the present study suggested that miR-26a negatively regulated the expression of FAM98A, indicating that it may play a key role in the suppression of breast carcinogenesis.

Gli activation by the estrogen receptor in breast cancer cells: Regulation of cancer cell growth by Gli3

BACKGROUND

Gli is an oncogenic transcription factor family thought to be involved in breast cancer (BrCa) cell growth. Gli activity is regulated by a post-translational proteolytic process that is suppressed by Hedgehog signaling. In prostate cancer cells, however, Gli activation is mediated by an interaction of active androgen receptor proteins with Gli3 that stabilizes Gli3 in its un-proteolyzed form. Here we show that the estrogen receptor (ER), ERα, also binds Gli3 and activates Gli in BrCa cells. Moreover, we show that ER + BrCa cells are dependent on Gli3 for cancer cell growth.

METHODS

Transfection with Gli-luciferase reporter was used to report Gli activity in 293FT or BrCa cells (MCF7, T47D, MDA-MB-453) with or without steroid ligands. Co-immunoprecipitation and proximity ligation were used to show association of Gli3 with ERα. Gli3 stability was determined by western blots of BrCa cell extracts. ERα knockdown or destabilization (by fulvestrant) was used to assess how loss of ERα affects estradiol-induced Gli reporter activity, formation of intranuclear ERα-Gli3 complexes and Gli3 stability. Expression of Gli1 and/or other endogenous Gli-target genes in BrCa cells were measured by qPCR in the presence or absence of estradiol. Gli3 knockdown was assessed for effects on BrCa cell growth using the Cyquant assay.

RESULTS

ERα co-transfection increased Gli reporter activity in 293FT cells that was further increased by estradiol. Gli3 co-precipitated in ERα immunoprecipitates. Acute (2 h) estradiol increased Gli reporter activity and the formation of intranuclear ERα-Gli3 complexes in ER + BrCa cells but more chronic estradiol (48 h) reduced ERα-Gli complexes commensurate with reduced ERα levels. Gli3 stability and endogenous activity was only increased by more chronic estradiol treatment. Fulvestrant or ERα knockdown suppressed E2-induction of Gli activity, intranuclear ERα-Gli3 complexes and stabilization of Gli3. Gli3 knockdown significantly reduced the growth of BrCa cells.

CONCLUSIONS

ERα interacts with Gli3 in BrCa cells and estradiol treatment leads to Gli3 stabilization and increased expression of Gli-target genes. Furthermore, we found tthat Gli3 is necessary for BrCa cell growth. These results support the idea that the ERα-Gli interaction and Gli3 may be novel targets for effective control of BrCa growth.

Hedgehog Signaling: Implications in Cancers and Viral Infections

The hedgehog (SHH) signaling pathway is primarily involved in embryonic gut development, smooth muscle differentiation, cell proliferation, adult tissue homeostasis, tissue repair following injury, and tissue polarity during the development of vertebrate and invertebrate organisms. GLIoma-associated oncogene homolog (GLI) family of zinc-finger transcription factors and smoothened (SMO) are the signal transducers of the SHH pathway. Both SHH ligand-dependent and independent mechanisms activate GLI proteins. Various transcriptional mechanisms, posttranslational modifications (phosphorylation, ubiquitination, proteolytic processing, SUMOylation, and acetylation), and nuclear-cytoplasmic shuttling control the activity of SHH signaling pathway proteins. The dysregulated SHH pathway is associated with bone and soft tissue sarcomas, GLIomas, medulloblastomas, leukemias, and tumors of breast, lung, skin, prostate, brain, gastric, and pancreas. While extensively studied in development and sarcomas, GLI family proteins play an essential role in many host-pathogen interactions, including bacterial and viral infections and their associated cancers. Viruses hijack host GLI family transcription factors and their downstream signaling cascades to enhance the viral gene transcription required for replication and pathogenesis. In this review, we discuss a distinct role(s) of GLI proteins in the process of tumorigenesis and host-pathogen interactions in the context of viral infection-associated malignancies and cancers due to other causes. Here, we emphasize the potential of the Hedgehog (HH) pathway targeting as a potential anti-cancer therapeutic approach, which in the future could also be tested in infection-associated fatalities.

Breast cancer stem cells: A review of their characteristics and the agents that affect them

The evolving concept that cancer stem cells (CSCs) are the driving element in cancer development, evolution and heterogeneity, has overridden the previous model of a tumor consisting of cells all with similar sequentially acquired mutations and a similar potential for renewal, invasion and metastasis. This paradigm shift has focused attention on therapeutically targeting CSCs directly as a means of eradicating the disease. In breast cancers, CSCs can be identified by cell surface markers and are characterized by their ability to self-renew and differentiate, resist chemotherapy and radiation, and initiate new tumors upon serial transplantation in xenografted mice. These functional properties of CSCs are regulated by both intracellular and extracellular factors including pluripotency-related transcription factors, intracellular signaling pathways and external stimuli. Several classes of natural products and synthesized compounds have been studied to target these regulatory elements and force CSCs to lose stemness and/or terminally differentiate and thereby achieve a therapeutic effect. However, realization of an effective treatment for breast cancers, focused on the biological effects of these agents on breast CSCs, their functions and signaling, has not yet been achieved. In this review, we delineate the intrinsic and extrinsic factors identified to date that control or promote stemness in breast CSCs and provide a comprehensive compilation of potential agents that have been studied to target breast CSCs, transcription factors and stemness-related signaling. Our aim is to stimulate further study of these agents that could become the basis for their use as stand-alone treatments or components of combination therapies effective against breast cancers.

Prognostic significance of hedgehog signaling network-related gene expression in breast cancer patients

Breast cancer continues to be a serious public health problem. The role of the hedgehog pathway in normal development of the mammary gland as well as in carcinogenesis and progression of breast cancer is the subject of intense investigation, revealing functional interactions with cell surface heparan sulfate. Nevertheless, its influence on breast cancer prognosis, and its relation to specific sulfation motifs in heparan sulfate have only been poorly studied in large patient cohorts. Using the public database KMplotter that includes gene expression and survival data of 3951 patients, we found that the higher expression of SHH, HHAT, PTCH1, GLI1, GLI2, and GLI3 positively influences breast cancer prognosis. Stratifying patients according to the expression of hormone receptors, histological grade, lymph node metastasis, and systemic therapy, we observed that GLI1, GLI2, and GLI3 expression, as well as co-expression of SHH and ELP1 were associated with worse relapse-free survival in patients with HER2-positive tumors. Moreover, GLI1 expression in progesterone receptor-negative tumors and GLI3 expression in grade 3 tumors correlated with poor prognosis. SHH, in a panel of cell lines representing different breast cancer subtypes, and HHAT, PTCH1, GLI1, GLI2, and GLI3 were mostly expressed in cell lines classified as HER2-positive and basal-like. Expression of SHH, HHAT, GLI2, and GLI3 was differentially affected by overexpression of the heparan sulfate sulfotransferases HS2ST1 and HS3ST2 in vitro. Although high HS2ST1 expression was associated with poor prognosis in KMplotter analysis, high levels of HS3ST2 were associated with a good prognosis, except for ER-positive breast cancer. We suggest the GLI transcription factors as possible markers for the diagnosis, treatment, and prognosis of breast cancer especially in HER2-positive tumors, but also in progesterone receptor-negative and grade-3 tumors. The pathway interaction and prognostic impact of specific heparan sulfate sulfotransferases provide novel perspectives regarding a therapeutical targeting of the hedgehog pathway in breast cancer.

Breast Cancer Stem Cells: Biomarkers, Identification and Isolation Methods, Regulating Mechanisms, Cellular Origin, and Beyond

Despite recent advances in diagnosis and treatment, breast cancer (BC) is still a major cause of cancer-related mortality in women. Breast cancer stem cells (BCSCs) are a small but significant subpopulation of heterogeneous breast cancer cells demonstrating strong self-renewal and proliferation properties. Accumulating evidence has proved that BCSCs are the driving force behind BC tumor initiation, progression, metastasis, drug resistance, and recurrence. As a heterogeneous disease, BC contains a full spectrum of different BC subtypes, and different subtypes of BC further exhibit distinct subtypes and proportions of BCSCs, which correspond to different treatment responses and disease-specific outcomes. This review summarized the current knowledge of BCSC biomarkers and their clinical relevance, the methods for the identification and isolation of BCSCs, and the mechanisms regulating BCSCs. We also discussed the cellular origin of BCSCs and the current advances in single-cell lineage tracing and transcriptomics and their potential in identifying the origin and lineage development of BCSCs.

The Role of Smoothened in Cancer

Smoothened (SMO) belongs to the Hedgehog (HH) signaling pathway, which regulates cell growth, migration, invasion and stem cells in cancer. The HH signaling pathway includes both canonical and noncanonical pathways. The canonical HH pathway functions through major HH molecules such as HH ligands, PTCH, SMO and GLI, whereas the noncanonical HH pathway involves the activation of SMO or GLI through other pathways. The role of SMO has been discussed in different types of cancer, including breast, liver, pancreatic and colon cancers. SMO expression correlates with tumor size, invasiveness, metastasis and recurrence. In addition, SMO inhibitors can suppress cancer formation, reduce the proliferation of cancer cells, trigger apoptosis and suppress cancer stem cell activity. A better understanding of the role of SMO in cancer could contribute to the development of novel therapeutic approaches.

Hedgehog Signaling and Truncated GLI1 in Cancer

The hedgehog (HH) signaling pathway regulates normal cell growth and differentiation. As a consequence of improper control, aberrant HH signaling results in tumorigenesis and supports aggressive phenotypes of human cancers, such as neoplastic transformation, tumor progression, metastasis, and drug resistance. Canonical activation of HH signaling occurs through binding of HH ligands to the transmembrane receptor Patched 1 (PTCH1), which derepresses the transmembrane G protein-coupled receptor Smoothened (SMO). Consequently, the glioma-associated oncogene homolog 1 (GLI1) zinc-finger transcription factors, the terminal effectors of the HH pathway, are released from suppressor of fused (SUFU)-mediated cytoplasmic sequestration, permitting nuclear translocation and activation of target genes. Aberrant activation of this pathway has been implicated in several cancer types, including medulloblastoma, rhabdomyosarcoma, basal cell carcinoma, glioblastoma, and cancers of lung, colon, stomach, pancreas, ovarian, and breast. Therefore, several components of the HH pathway are under investigation for targeted cancer therapy, particularly GLI1 and SMO. GLI1 transcripts are reported to undergo alternative splicing to produce truncated variants: loss-of-function GLI1ΔN and gain-of-function truncated GLI1 (tGLI1). This review covers the biochemical steps necessary for propagation of the HH activating signal and the involvement of aberrant HH signaling in human cancers, with a highlight on the tumor-specific gain-of-function tGLI1 isoform.

Hedgehog Signal Inhibitor GANT61 Inhibits the Malignant Behavior of Undifferentiated Hepatocellular Carcinoma Cells by Targeting Non-Canonical GLI Signaling

The Hedgehog (HH)–GLI pathway plays an important role in cell dedifferentiation and is therefore pivotally involved in the malignant transformation of cancer cells. GANT61, a selective inhibitor of GLI1 and GLI2, was reported as a promising treatment for cancer in various tissues; however, the biological impact of GANT61 in hepatocellular carcinoma (HCC), especially in undifferentiated HCC cells, remains unclear. In this study, we investigated the antitumor effect of GANT61 using two undifferentiated hepatoma cell lines: HLE and HLF. Quantitative PCR and RT-PCR analyses revealed that these cells express GLI transcripts, showing mesenchymal phenotypes characterized by the loss of epithelial and hepatic markers and specific expression of epithelial–mesenchymal transition (EMT)-related genes. GANT61 significantly reduced the proliferation and cell viability after drug treatment using 5-FU and Mitomycin C. We showed that GLI transcript levels were down-regulated by the MEK inhibitor U0126 and the Raf inhibitor sorafenib, suggesting that non-canonical signaling including the Ras–Raf–MEK–ERK pathway is involved. Sphere formation and migration were significantly decreased by GANT61 treatment, and it is suggested that the underlying molecular mechanisms are the down-regulation of stemness-related genes (Oct4, Bmi1, CD44, and ALDH) and the EMT-related gene Snail1. The data presented here showed that direct inhibition of GLI might be beneficial for the treatment of dedifferentiated HCC.

The multiple function of long noncoding RNAs in osteosarcoma progression, drug resistance and prognosis

Osteosarcoma is a bone tumor prevalent in children and young adults. LncRNAs are a family of non-protein-coding transcripts longer than 200 nucleotides. The tumor-related pathological functions of lncRNAs include proliferation, migration, and chemotherapy resistance, all of which have been widely acknowledged in research on osteosarcoma. In addition, compelling evidence suggests that lncRNAs could serve as diagnostic indicators, prognostic biomarkers, and targets for disease treatment. In this review, we systematically summarize how lncRNAs regulate tumorigenesis, invasion and therapeutic resistance. By deepening our knowledge of the relationship between lncRNAs and osteosarcoma, we hope to translate research findings into clinical applications as soon as possible.

Sonic Hedgehog Signaling in Organogenesis, Tumors, and Tumor Microenvironments

During mammalian embryonic development, primary cilia transduce and regulate several signaling pathways. Among the various pathways, Sonic hedgehog (SHH) is one of the most significant. SHH signaling remains quiescent in adult mammalian tissues. However, in multiple adult tissues, it becomes active during differentiation, proliferation, and maintenance. Moreover, aberrant activation of SHH signaling occurs in cancers of the skin, brain, liver, gallbladder, pancreas, stomach, colon, breast, lung, prostate, and hematological malignancies. Recent studies have shown that the tumor microenvironment or stroma could affect tumor development and metastasis. One hypothesis has been proposed, claiming that the pancreatic epithelia secretes SHH that is essential in establishing and regulating the pancreatic tumor microenvironment in promoting cancer progression. The SHH signaling pathway is also activated in the cancer stem cells (CSC) of several neoplasms. The self-renewal of CSC is regulated by the SHH/Smoothened receptor (SMO)/Glioma-associated oncogene homolog I (GLI) signaling pathway. Combined use of SHH signaling inhibitors and chemotherapy/radiation therapy/immunotherapy is therefore key in targeting CSCs.

Mutation of the PTCH1 gene predicts recurrence of breast cancer

Breast cancer is the most common cancer in women, and some patients develop recurrence after standard therapy. Effective predictors are urgently needed to detect recurrence earlier. The activation of Hedgehog signaling in breast cancer is correlated with poor prognosis. PTCH1 is an essential membrane receptor of Hedgehog. However, there are few reports about mutations in Hedgehog genes in breast cancer. We conducted a comprehensive study via an experimental and bioinformatics approach to detect mutated genes in breast cancer. Twenty-two breast cancer patients who developed recurrence within 24 months postoperatively were enrolled with 22 control cancer patients. Targeted deep sequencing was performed to assess the mutations among individuals with breast cancer using a panel of 143 cancer-associated genes. Bioinformatics and public databases were used to predict the protein functions of the mutated genes. Mutations were identified in 44 breast cancer specimens, and the most frequently mutated genes were BRCA2, APC, ATM, BRCA1, NF1, TET2, TSC1, TSC2, NOTCH1, MSH2, PTCH1, TP53, PIK3CA, FBXW7, and RB1. Mutation of these genes was correlated with protein phosphorylation and autophosphorylation, such as peptidyl-tyrosine and protein kinase C phosphorylation. Among these highly mutated genes, mutations of PTCH1 were associated with poor prognosis and increased recurrence of breast cancer, especially mutations in exons 22 and 23. The public sequencing data from the COSMIC database were exploited to predict the functions of the mutations. Our findings suggest that mutation of PTCH1 is correlated with early recurrence of breast cancer patients and will become a powerful predictor for recurrence of breast cancer.

Mesenchymal Cells Support the Oncogenicity and Therapeutic Response of the Hedgehog Pathway in Triple-Negative Breast Cancer

The paracrine interaction between tumor cells and adjacent stroma has been associated with the oncogenic activity of the Hedgehog (Hh) pathway in triple-negative breast tumors. The present study developed a model of paracrine Hh signaling and examined the impact of mesenchymal cell sources and culture modalities in the oncogenicity of the Hh pathway in breast tumor cells. Studies consisted of tumor cell monocultures and co-cultures with cancer-associated and normal fibroblasts, tumor cells that undergo epithelial–mesenchymal transition (EMT), or adipose-derived mesenchymal stem cells (ADMSCs). Hh ligand and pathway inhibitors, GANT61 and NVP-LDE225 (NVP), were evaluated in both cell cultures and a mouse xenograft model. Results in monocultures show that tumor cell viability and Hh transcriptional activity were not affected by Hh inhibitors. In co-cultures, down-regulation of GLI1, SMO, and PTCH1 in the stroma correlated with reduced tumor growth rates in xenografted tumors and cell cultures, confirming a paracrine interaction. Fibroblasts and EMT cells supported Hh transcriptional activity and enhanced tumor cell growth. Mixed and adjacent culture modalities indicate that tumor growth is supported via fibroblast-secreted soluble factors, whereas enriched tumor stemness requires close proximity between tumor and fibroblasts. Overall this study provides a tumor–mesenchymal model of Hh signaling and highlights the therapeutic value of mesenchymal cells in the oncogenic activity of the Hh pathway.

The Hedgehog Signaling Pathway: A Viable Target in Breast Cancer?

The hedgehog (Hh) pathway plays a key role in embryonic development and stem cell programs. Deregulation of the Hh pathway is a key driver of basal cell carcinoma, and therapeutic targeting led to approval of Hh inhibitor, vismodegib, in the management of this cancer. The Hh pathway is implicated in other malignancies including hormone receptor (HR+) positive and triple negative breast cancer (TNBC). Hh signaling, which is activated in human mammary stem cells, results in activation of glioma-associated oncogene (GLI) transcription factors. High GLI1 expression correlates with worse outcomes in breast cancer. Non-canonical GLI1 activation is one mechanism by which estrogen exposure promotes breast cancer stem cell proliferation and epithelial–mesenchymal transition. Tamoxifen resistant cell lines show aberrant activation of Hh signaling, and knockdown of Hh pathway inhibited growth of tamoxifen resistant cells. As in other cancers Hh signaling is activated by the PI3K/AKT pathway in these endocrine resistant cell lines. Hh pathway activation has also been reported to mediate chemotherapy resistance in TNBC via various mechanisms including paracrine signaling to tumor micro-environment and selective proliferation of cancer stem cells. Co-activation of Hh and Wnt signaling pathways is a poor prognostic marker in TNBC. Early phase clinical trials are evaluating the combination of smoothened (SMO) inhibitors and chemotherapy in TNBC. In addition to SMO inhibitors like vismodegib and sonidegib, which are in clinical use for basal cell carcinoma, GLI1 inhibitors like GANT58 and GANT61 are in preclinical drug development and might be an effective mechanism to overcome drug resistance in breast cancer. Gene signatures predictive of Hh pathway activation could enrich for patients likely to respond to these agents.

Carbonic anhydrase XII expression is linked to suppression of Sonic hedgehog ligand expression in triple negative breast cancer cells

Aberrant activity of the hedgehog (Hh) pathway is prevalent in pathologies such as cancer. Improved understanding of Hh activity in the aggressive tumor cell phenotype is being pursued for development of targeted therapies. Recently, we described a link between Hh activity and carbonic anhydrase XII (CAXII) expression. Extracellular facing CAs (IX/XII) are highly expressed in hypoxia, contribute to tumor pH regulation and are thus of clinical interest. Here we have extended the investigation of potential interactions between Hh activity and CAXII utilizing genomic disruption/knockout of either GLI1 (the main transcriptional factor induced with Hh activity) or CAXII in the triple negative breast cancer cell lines MDA-MB-231 and BT-549. Knockout of GLI1 and CAXII significantly decreased hallmarks of tumor aggressiveness including proliferation and migration. Most intriguingly, CAXII knockout caused a massive induction of the Sonic hedgehog (Shh) ligand expression (gene and protein). This novel finding indicates that CAXII plays a potential role in suppression of Shh and may act in a feedback loop to regulate overall Hh activity. Enhanced knowledge of these CA-Hh interactions in future studies may be of value in understanding this currently 'incurable' subclass of breast cancer.

Genomic testing, tumor microenvironment and targeted therapy of Hedgehog-related human cancers

Hedgehog signals are transduced through Patched receptors to the Smoothened (SMO)-SUFU-GLI and SMO-Gi-RhoA signaling cascades. MTOR-S6K1 and MEK-ERK signals are also transduced to GLI activators through post-translational modifications. The GLI transcription network up-regulates target genes, such as BCL2, FOXA2, FOXE1, FOXF1, FOXL1, FOXM1, GLI1, HHIP, PTCH1 and WNT2B, in a cellular context-dependent manner. Aberrant Hedgehog signaling in tumor cells leads to self-renewal, survival, proliferation and invasion. Paracrine Hedgehog signaling in the tumor microenvironment (TME), which harbors cancer-associated fibroblasts, leads to angiogenesis, fibrosis, immune evasion and neuropathic pain. Hedgehog-related genetic alterations occur frequently in basal cell carcinoma (BCC) (85%) and Sonic Hedgehog (SHH)-subgroup medulloblastoma (87%) and less frequently in breast cancer, colorectal cancer, gastric cancer, pancreatic cancer, non-small-cell lung cancer (NSCLC) and ovarian cancer. Among investigational SMO inhibitors, vismodegib and sonidegib are approved for the treatment of patients with BCC, and glasdegib is approved for the treatment of patients with acute myeloid leukemia (AML). Resistance to SMO inhibitors is caused by acquired SMO mutations, SUFU deletions, GLI2 amplification, other by-passing mechanisms of GLI activation and WNT/β-catenin signaling activation. GLI-DNA-interaction inhibitors (glabrescione B and GANT61), GLI2 destabilizers (arsenic trioxide and pirfenidone) and a GLI-deacetylation inhibitor (4SC-202) were shown to block GLI-dependent transcription and tumorigenesis in preclinical studies. By contrast, SMO inhibitors can remodel the immunosuppressive TME that is dominated by M2-like tumor-associated macrophages (M2-TAMs), myeloid-derived suppressor cells and regulatory T cells, and thus, a Phase I/II clinical trial of the immune checkpoint inhibitor pembrolizumab with or without vismodegib in BCC patients is ongoing.

Influence of SHH/GLI1 axis on EMT mediated migration and invasion of breast cancer cells

Sonic Hedgehog signaling is critical for breast morphogenesis and cancer. The present study was conducted to explore the influence of SHH/GLI1 axis on epithelial mesenchymal transition and invasion in breast cancer cells. SHH/GLI1 positive samples demonstrated high expression of Snail and Vimentin with relatively low expression of E-cadherin. Overexpression of Vimentin and Snail in SHH/GLI1 positive patients was also associated with poor overall survival. Interestingly, GANT61 (GLI1 inhibitor) exposure significantly reduced cell viability and induced apoptosis at 10 µM. Suppression of Hedgehog pathway either by CRISPR mediated SHH knock out or GANT61 altered regulation of EMT markers in breast cancer cells. Moreover, in-activation of SHH/GLI1 axis also significantly restricted cell migration and invasiveness. These findings suggest that targeting SHH/GLI1 axis alters expression of EMT markers and abrogates neoplastic invasion in breast cancer cells.

Role of Hedgehog Signaling in Breast Cancer: Pathogenesis and Therapeutics

Breast cancer (BC) is the leading cause of cancer-related mortality in women, only followed by lung cancer. Given the importance of BC in public health, it is essential to identify biomarkers to predict prognosis, predetermine drug resistance and provide treatment guidelines that include personalized targeted therapies. The Hedgehog (Hh) signaling pathway plays an essential role in embryonic development, tissue regeneration, and stem cell renewal. Several lines of evidence endorse the important role of canonical and non-canonical Hh signaling in BC. In this comprehensive review we discuss the role of Hh signaling in breast development and homeostasis and its contribution to tumorigenesis and progression of different subtypes of BC. We also examine the efficacy of agents targeting different components of the Hh pathway both in preclinical models and in clinical trials. The contribution of the Hh pathway in BC tumorigenesis and progression, its prognostic role, and its value as a therapeutic target vary according to the molecular, clinical, and histopathological characteristics of the BC patients. The evidence presented here highlights the relevance of the Hh signaling in BC, and suggest that this pathway is key for BC progression and metastasis.

Inhibition of smoothened in breast cancer cells reduces CAXII expression and cell migration

Breast cancer (BC) relapse and metastasis are the leading cause of death and, together with drug resistance, keep mortality still high. The Hedgehog (Hh) pathway is expressed during embryogenesis, organogenesis and in adult tissue homeostasis and its aberrant activation is often associated with cancer. Carbonic anhydrase (CA) enzymes are important during development; they play a key role in controlling several cellular mechanisms, such as pH regulation, survival, and migration, and they are aberrantly expressed in cancer. The goal of this study was to investigate the interplay between the Hh pathway and CAXII in terms of BC cell migration. We here demonstrated that smoothened (SMO) silencing resulted in a reduction of CAXII expression at mRNA and protein level. This led to a decrease in cell migration, which was restored when cells were treated with an SMO agonist, Sag dihydrochloride (SAG), but not when cells were cotreated with SAG and the CAs inhibitor Acetazolamide. This suggested that the ability of SAG to promote cell migration was impaired when CAXII was inhibited. The reduction was also confirmed within hypoxic and inflammatory microenvironment, typical of BC, indicating a key role of the Hh pathway in controlling CAXII expression. Our results may contribute to further understand the physiology of BC cells and indicate that the Hh pathway controls BC cell migration and cell invasion also through CAXII, with important implications in identifying novel therapeutic targets.

Comprehensive immunohistochemical analyses on expression levels of hedgehog signaling molecules in breast cancers

BACKGROUND

The hedgehog (Hh) signaling pathway plays important roles in cell proliferation, malignant progression, invasion and metastasis, and the expansion of cancer stem cells (CSCs). Comprehensive immunohistochemical (IHC) analyses have not yet been conducted on the expression levels of Hh signaling molecules in breast cancer tissues.

METHODS

A total of 204 patients with invasive breast cancer treated in our institute were study subjects. IHC analyses on the expression levels of the Hh signaling molecules, sonic Hh (SHH), PTCH1, GLI1, GLI2, and GLI3 and the CSC-related factor, SOX2, were investigated.

RESULTS

Positive correlations were observed among all of the Hh signaling molecules tested. SOX2 expression correlated with the expression levels of all Hh signaling molecules. SHH expression positively correlated with tumor size, the Ki-67 labeling index, histological grade, estrogen receptor negativity, progesterone receptor negativity, and HER2 positivity. GLI1 expression positively correlated with the histological grade. GLI2 expression positively correlated with the histological grade, Ki-67 labeling index, and HER2 positivity. Univariate analyses revealed that a younger age, larger tumor size, positive lymph node metastasis, higher histological grade, positive lymphatic invasion, and higher Ki-67 labeling index were related to poor relapse-free survival (RFS). The positivity of all Hh signaling molecules and SOX2 did not correlate with poor RFS. A multivariate analysis revealed that positive lymphatic invasion and a younger age were independent worse prognostic factors for RFS.

CONCLUSIONS

This comprehensive analysis demonstrated for the first time that SHH, GLI1, and GLI2 expression levels positively correlated with the malignant phenotypes of tumor cells.

Glioma-Associated Oncogene Homolog Inhibitors Have the Potential of Suppressing Cancer Stem Cells of Breast Cancer

Overexpression of Sonic Hedgehog signaling (Shh) pathway molecules is associated with invasiveness and recurrence in breast carcinoma. Therefore, inhibition of the Shh pathway downstream molecule Glioma-associated Oncogene Homolog (Gli) was investigated for its ability to reduce progression and invasiveness of patient-derived breast cancer cells and cell lines. Human primary breast cancer T2 cells with high expression of Shh signaling pathway molecules were compared with breast cancer line MDA-MB-231 cells. The therapeutic effects of Gli inhibitors were examined in terms of the cell proliferation, apoptosis, cancer stem cells, cell migration and gene expression. Blockade of the Shh signaling pathway could reduce cell proliferation and migration only in MDA-MB-231 cells. Hh pathway inhibitor-1 (HPI-1) increased the percentages of late apoptotic cells in MDA-MB-231 cells and early apoptotic cells in T2 cells. It reduced Bcl2 expression for cell proliferation and increased Bim expression for apoptosis. In addition, Gli inhibitor HPI-1 decreased significantly the percentages of cancer stem cells in T2 cells. HPI-1 worked more effectively than GANT-58 against breast carcinoma cells. In conclusion, HPI-1 could inhibit cell proliferation, reduce cell invasion and decrease cancer stem cell population in breast cancer cells. To target Gli-1 could be a potential strategy to suppress breast cancer stem cells.

Activated coagulation time in monitoring heparinized dogs

Breast cancer stem cells (BCSCs) are the minor population of breast cancer (BC) cells that exhibit several phenotypes such as migration, invasion, self-renewal, and chemotherapy as well as radiotherapy resistance. Recently, BCSCs have been more considerable due to their capacity for recurrence of tumors after treatment. Recognition of signaling pathways and molecular mechanisms involved in stemness phenotypes of BCSCs could be effective for discovering novel treatment strategies to target BCSCs. This review introduces BCSC markers, their roles in stemness phenotypes, and the dysregulated signaling pathways involved in BCSCs such as mitogen-activated protein (MAP) kinase, PI3K/Akt/nuclear factor kappa B (NFκB), TGF-β, hedgehog (Hh), Notch, Wnt/β-catenin, and Hippo pathway. In addition, this review presents recently discovered molecular mechanisms implicated in chemotherapy and radiotherapy resistance, migration, metastasis, and angiogenesis of BCSCs. Finally, we reviewed the role of microRNAs (miRNAs) in BCSCs as well as several other therapeutic strategies such as herbal medicine, biological agents, anti-inflammatory drugs, monoclonal antibodies, nanoparticles, and microRNAs, which have been more considerable in the last decades.