Targeting Notch1 and IKKα Enhanced NF-κB Activation in CD133+ Skin Cancer Stem Cells

Cancer stem cells: advances in knowledge and implications for cancer therapy

Cancer stem cells (CSCs), a small subset of cells in tumors that are characterized by self-renewal and continuous proliferation, lead to tumorigenesis, metastasis, and maintain tumor heterogeneity. Cancer continues to be a significant global disease burden. In the past, surgery, radiotherapy, and chemotherapy were the main cancer treatments. The technology of cancer treatments continues to develop and advance, and the emergence of targeted therapy, and immunotherapy provides more options for patients to a certain extent. However, the limitations of efficacy and treatment resistance are still inevitable. Our review begins with a brief introduction of the historical discoveries, original hypotheses, and pathways that regulate CSCs, such as WNT/β-Catenin, hedgehog, Notch, NF-κB, JAK/STAT, TGF-β, PI3K/AKT, PPAR pathway, and their crosstalk. We focus on the role of CSCs in various therapeutic outcomes and resistance, including how the treatments affect the content of CSCs and the alteration of related molecules, CSCs-mediated therapeutic resistance, and the clinical value of targeting CSCs in patients with refractory, progressed or advanced tumors. In summary, CSCs affect therapeutic efficacy, and the treatment method of targeting CSCs is still difficult to determine. Clarifying regulatory mechanisms and targeting biomarkers of CSCs is currently the mainstream idea.

Can CD133 Be Regarded as a Prognostic Biomarker in Oncology: Pros and Cons

The CD133 cell membrane glycoprotein, also termed prominin-1, is expressed on some of the tumor cells of both solid and blood malignancies. The CD133-positive tumor cells were shown to exhibit higher proliferative activity, greater chemo- and radioresistance, and enhanced tumorigenicity compared to their CD133-negative counterparts. For this reason, CD133 is regarded as a potential prognostic biomarker in oncology. The CD133-positive cells are related to the cancer stem cell subpopulation in many types of cancer. Recent studies demonstrated the involvement of CD133 in the regulation of proliferation, autophagy, and apoptosis in cancer cells. There is also evidence of its participation in the epithelial-mesenchymal transition associated with tumor progression. For a number of malignant tumor types, high CD133 expression is associated with poor prognosis, and the prognostic significance of CD133 has been confirmed in a number of meta-analyses. However, some published papers suggest that CD133 has no prognostic significance or even demonstrate a certain correlation between high CD133 levels and a positive prognosis. This review summarizes and discusses the existing evidence for and against the prognostic significance of CD133 in cancer. We also consider possible reasons for conflicting findings from the studies of the clinical significance of CD133.

Baicalin Antagonizes Prostate Cancer Stemness via Inhibiting Notch1/NF-κB Signaling Pathway

OBJECTIVE

To investigate the molecular mechanisms underlying the effect of baicalin on prostate cancer (PCa) progression both in vivo and in vitro.

METHODS

The in situ PCa stem cells (PCSCs)-injected xenograft tumor models were established in BALB/c nude mice. Tumor volume and weight were respectively checked after baicalin (100 mg/kg) treatment. Hematoxylin-eosin (HE) staining was used to observe the growth arrest and cell necrosis. mRNA expression levels of acetaldehyde dehydrogenase 1 (ALDH1), CD44, CD133 and Notch1 were determined by reverse transcription-polymerase chain reaction. Protein expression levels of ALDH1, CD44, CD133, Notch1, nuclear factor κB (NF-κB) P65 and NF-κB p-P65 were detected by Western blot. Expression and subcellular location of ALDH1, CD44, CD133, Notch1 and NF-κB p65 were detected by immunofluorescence analysis. In vitro, cell cycle distribution and cell apoptosis of PC3 PCSCs was assessed by flow cytometry after baicalin (125 µmol/L) treatment. The migration and invasion abilities of PCSCs were assessed using Transwell assays. Transmission electron microscopy scanning was utilized to observe the structure and autophagosome formation of baicalin-treated PCSCs. In addition, PCSCs were infected with lentiviruses expressing human Notch1.

RESULTS

Compared with the control group, the tumor volume and weight were notably reduced in mice treated with 100 mg/kg baicalin (P<0.05 or P<0.01). Histopathological analysis showed that baicalin treatment significantly inhibited cell proliferation and promoted cell apoptosis. Furthermore, baicalin treatment reduced mRNA and protein expression levels of CD44, CD133, ALDH1, and Notch1 as well as the protein expression of NF-κB p-P65 in the xenograft tumor (P<0.01). In vitro, the cell proliferation of PCSCs was significantly attenuated after treatment with 125 µmol/L baicalin for 72 h (P<0.01). The cell migration and invasion rates were decreased following treatment with baicalin for 48 and 72 h (P<0.01). Baicalin notably induced cell apoptosis and seriously damaged the structure of PCSCs. The mRNA and protein expressions of CD133, CD44, ALDH1 and Notch1 in PCSCs were significantly downregulated following baicalin treatment (P<0.01). Importantly, the inhibitory effects of baicalin on PCa progression and stemness were reversed by Notch1 overexpression (P<0.05 or P<0.01).

CONCLUSION

Mechanistically, baicalin exhibited a potential therapeutic effect on PCa via inhibiting the Notch1/NF-κB signaling pathway and its mediated cancer stemness.

SHCBP1 contributes to the proliferation and self‑renewal of cervical cancer cells and activation of the NF‑κB signaling pathway through EIF5A

Cervical cancer (CC) is the most common human papillomavirus-related disease. Continuous activation of the NF-κB signaling pathway has been observed in CC. SHC binding and spindle associated 1 (SHCBP1) contributes to tumorigenesis and activation of the NF-κB pathway in multiple cancer types, while its function in CC remains unclear. In the present study, three Gene Expression Omnibus datasets were used to identify differentially expressed genes (DEGs) in CC. Loss- and gain-of-function experiments were performed using stable SHCBP1-silenced and SHCBP1-overexpressing CC cells. To further explore the molecular mechanism of SHCBP1 in CC, small interfering RNA targeting eukaryotic translation initiation factor 5A (EIF5A) was transfected into stable SHCBP1-overexpressing CC cells. The results demonstrated that SHCBP1 was an upregulated DEG in CC tissues compared with healthy control cervical tissues. Functional experiments revealed the pro-proliferative and pro-stemness role of SHCBP1 in CC cells (CaSki and SiHa cells), in vitro. Furthermore, the NF-κB signaling pathway in CC cells was activated by SHCBP1. Increases in cell proliferation, stemness and activation of NF-κB, induced by SHCBP1 overexpression in CC cells, were reversed by EIF5A knockdown. Taken together, the results indicated that SHCBP1 serves an important role in regulation of CC cell proliferation, self-renewal and activation of NF-κB via EIF5A. The present study demonstrated a potential molecular mechanism underlying the progression of CC.

Molecular Alterations in Cutaneous Squamous Cell Carcinoma in Immunocompetent and Immunosuppressed Hosts-A Systematic Review

The characterization of cutaneous squamous cell carcinoma (cSCC) at the molecular level is lacking in the current literature due to the high mutational burden of this disease. Immunosuppressed patients afflicted with cSCC experience considerable morbidity and mortality. In this article, we review the molecular profile of cSCC among the immunosuppressed and immunocompetent populations at the genetic, epigenetic, transcriptomic, and proteometabolomic levels, as well as describing key differences in the tumor immune microenvironment between these two populations. We feature novel biomarkers from the recent literature which may serve as potential targets for therapy.

Targeting oncogenic transcription factors in skin malignancies: An update on cancer stemness and therapeutic outcomes

The skin is the largest organ of the human body and prone to various diseases, including cancer; thus, provides the first line of defense against exogenous biological and non-biological agents. Skin cancer, a complex and heterogenic process, with steep incidence rate often metastasizes due to poor understanding of the underlying mechanisms of pathogenesis and clinical challenges. Indeed, accumulating evidence indicates that deregulation of transcription factors (TFs) due to genetic, epigenetic and signaling distortions plays essential role in the development of cutaneous malignancies and therapeutic challenges including cancer stemness features and reprogramming. This review highlights the recent developments exploring underlying mechanisms how deregulated TFs (e.g., NF-κB, AP-1, STAT etc.,) orchestrates cutaneous onco-pathogenesis, reprogramming, stemness and poor clinical outcomes. Along this line, bioactive drugs, and their derivatives from natural and or synthetic origin has gained attention due to their multitargeting potential, potentially safer and effective therapeutic outcome for human malignancies. We also discussed therapeutic importance of targeting aberrantly expressed TFs in skin cancers with bioactive natural products and or synthetic agents.

Pleiotropic effects of DCLK1 in cancer and cancer stem cells

Doublecortin-like kinase 1 (DCLK1), a protein molecule, has been identified as a tumor stem cell marker in the cancer cells of gastrointestinal, pancreas, and human colon. DCLK1 expression in cancers, such as breast carcinoma, lung carcinoma, hepatic cell carcinoma, tuft cells, and human cholangiocarcinoma, has shown a way to target the DCLK1 gene and downregulate its expression. Several studies have discussed the inhibition of tumor cell proliferation along with neoplastic cell arrest when the DCLK1 gene, which is expressed in both cancer and normal cells, was targeted successfully. In addition, previous studies have shown that DCLK1 plays a vital role in various cancer metastases. The correlation of DCLK1 with numerous stem cell receptors, signaling pathways, and genes suggests its direct or an indirect role in promoting tumorigenesis. Moreover, the impact of DCLK1 was found to be related to the functioning of an oncogene. The downregulation of DCLK1 expression by using targeted strategies, such as embracing the use of siRNA, miRNA, CRISPR/Cas9 technology, nanomolecules, specific monoclonal antibodies, and silencing the pathways regulated by DCLK1, has shown promising results in both in vitro and in vivo studies on gastrointestinal (GI) cancers. In this review, we will discuss about the present understanding of DCLK1 and its role in the progression of GI cancer and metastasis.

Investigating Cutaneous Squamous Cell Carcinoma in vitro and in vivo: Novel 3D Tools and Animal Models

Cutaneous Squamous Cell Carcinoma (cSCC) represents the second most common type of skin cancer, which incidence is continuously increasing worldwide. Given its high frequency, cSCC represents a major public health problem. Therefore, to provide the best patients’ care, it is necessary having a detailed understanding of the molecular processes underlying cSCC development, progression, and invasion. Extensive efforts have been made in developing new models allowing to study the molecular pathogenesis of solid tumors, including cSCC tumors. Traditionally, in vitro studies were performed with cells grown in a two-dimensional context, which, however, does not represent the complexity of tumor in vivo. In the recent years, new in vitro models have been developed aiming to mimic the three-dimensionality (3D) of the tumor, allowing the evaluation of tumor cell-cell and tumor-microenvironment interaction in an in vivo-like setting. These models include spheroids, organotypic cultures, skin reconstructs and organoids. Although 3D models demonstrate high potential to enhance the overall knowledge in cancer research, they lack systemic components which may be solved only by using animal models. Zebrafish is emerging as an alternative xenotransplant model in cancer research, offering a high-throughput approach for drug screening and real-time in vivo imaging to study cell invasion. Moreover, several categories of mouse models were developed for pre-clinical purpose, including xeno- and syngeneic transplantation models, autochthonous models of chemically or UV-induced skin squamous carcinogenesis, and genetically engineered mouse models (GEMMs) of cSCC. These models have been instrumental in examining the molecular mechanisms of cSCC and drug response in an in vivo setting. The present review proposes an overview of in vitro, particularly 3D, and in vivo models and their application in cutaneous SCC research.

Notch signaling pathway: architecture, disease, and therapeutics

The NOTCH gene was identified approximately 110 years ago. Classical studies have revealed that NOTCH signaling is an evolutionarily conserved pathway. NOTCH receptors undergo three cleavages and translocate into the nucleus to regulate the transcription of target genes. NOTCH signaling deeply participates in the development and homeostasis of multiple tissues and organs, the aberration of which results in cancerous and noncancerous diseases. However, recent studies indicate that the outcomes of NOTCH signaling are changeable and highly dependent on context. In terms of cancers, NOTCH signaling can both promote and inhibit tumor development in various types of cancer. The overall performance of NOTCH-targeted therapies in clinical trials has failed to meet expectations. Additionally, NOTCH mutation has been proposed as a predictive biomarker for immune checkpoint blockade therapy in many cancers. Collectively, the NOTCH pathway needs to be integrally assessed with new perspectives to inspire discoveries and applications. In this review, we focus on both classical and the latest findings related to NOTCH signaling to illustrate the history, architecture, regulatory mechanisms, contributions to physiological development, related diseases, and therapeutic applications of the NOTCH pathway. The contributions of NOTCH signaling to the tumor immune microenvironment and cancer immunotherapy are also highlighted. We hope this review will help not only beginners but also experts to systematically and thoroughly understand the NOTCH signaling pathway.

Cancer stem cells: a major culprit of intra-tumor heterogeneity

Cancer is recognized as a preeminent factor of the world's mortality. Although various modalities have been designed to cure this life-threatening ailment, a significant impediment in the effective output of cancer treatment is heterogeneity. Cancer is characterized as a heterogeneous health disorder that comprises a distinct group of transformed cells to assist anomalous proliferation of affected cells. Cancer stem cells (CSCs) are a leading cause of cancer heterogeneity that is continually transformed by cellular extrinsic and intrinsic factors. They intensify neoplastic cells aggressiveness by strengthening their dissemination, relapse and therapy resistance. Considering this viewpoint, in this review article we have discussed some intrinsic (transcription factors, cell signaling pathways, genetic alterations, epigenetic modifications, non-coding RNAs (ncRNAs) and epitranscriptomics) and extrinsic factors (tumor microenvironment (TME)) that contribute to CSC heterogeneity and plasticity, which may help scientists to meddle these processes and eventually improve cancer research and management. Besides, the potential role of CSCs heterogeneity in establishing metastasis and therapy resistance has been articulated which signifies the importance of developing novel anticancer therapies to target CSCs along with targeting bulk tumor mass to achieve an effective output.

Oh, the Mutations You'll Acquire! A Systematic Overview of Cutaneous Squamous Cell Carcinoma

Nearly two million cases of cutaneous squamous cell carcinoma (cSCC) are diagnosed every year in the United States alone. cSCC is notable for both its prevalence and its propensity for invasion and metastasis. For many patients, surgery is curative. However, patients experiencing immunosuppression or recurrent, advanced, and metastatic disease still face limited therapeutic options and significant mortality. cSCC forms after decades of sun exposure and possesses the highest known mutation rate of all cancers. This mutational burden complicates efforts to identify the primary factors driving cSCC initiation and progression, which in turn hinders the development of targeted therapeutics. In this review, we summarize the mutations and alterations that have been observed in patients’ cSCC tumors, affecting signaling pathways, transcriptional regulators, and the microenvironment. We also highlight novel therapeutic opportunities in development and clinical trials.

Pterygium-The Good, the Bad, and the Ugly

Pterygium is a multifaceted pathology that displays apparent conflicting characteristics: benign (e.g., self-limiting and superficial), bad (e.g., proliferative and potentially recurrent) and ugly (e.g., signs of preneoplastic transformation). The natural successive question is: why are we lacking reports showing that pterygium lesions become life-threatening through metastasis, especially since pterygium has considerable similarities with UV-related malignancies on the molecular level? In this review, we consider how our pathophysiological understanding of the benign pterygium pathology overlaps with ocular surface squamous neoplasia and skin cancer. The three UV-related disorders share the same initial insult (i.e., UV radiation) and responsive repair mechanisms to the ensuing (in)direct DNA damage. Their downstream apoptotic regulators and other cellular adaptations are remarkably alike. However, a complicating factor in understanding the fine line between the self-limiting nature of pterygium and the malignant transformation in other UV-related diseases is the prominent ambiguity in the pathological evaluation of pterygium biopsies. Features of preneoplastic transformation (i.e., dysplasia) are used to define normal cellular reactions (i.e., atypia and metaplasia) and vice versa. A uniform grading system could help in unraveling the true nature of this ancient disease and potentially help in identifying the earliest intervention point possible regarding the cellular switch that drives a cell’s fate towards cancer.

KDF1, a Novel Tumor Suppressor in Clear Cell Renal Cell Carcinoma

KDF1 has been identified as a key regulator of epidermal proliferation and differentiation, but it is unknown whether KDF1 is involved in the pathogenesis of malignancy. No study has reported the expression and function of KDF1 in renal cancer. To explore the pathologic significance of KDF1 in clear cell renal cell carcinoma (ccRCC), the expression level of KDF1 protein in the tumor tissue of ccRCC patients was examined by immunohistochemistry and Western blot while the expression level of KDF1 mRNA was analyzed by using the data from TCGA database. In vitro cell experiments and allogeneic tumor transplantation tests were performed to determine the effects of altered KDF1 expression on the phenotype of ccRCC cells. Both the KDF1 mRNA and protein were found to be decreasingly expressed in the tumor tissue of ccRCC patients when compared with the adjacent non-tumor control tissue. The expression level of KDF1 in the tumor tissue was found to correlate negatively with the tumor grade. Patients with higher KDF1 in the tumor tissue were found to have longer overall survival and disease-specific survival time. KDF1 was shown to be an independent factor influencing the disease-specific survival of the ccRCC patients. Overexpression of KDF1 was found to inhibit the proliferation, migration and invasion of ccRCC cells, which could be reversed by decreasing the expression of KDF1 again. ccRCC cells with KDF1 overexpression were found to produce smaller transgrafted tumors. These results support the idea that KDF1 is involved in ccRCC and may function as a tumor suppressor.

The Impact of Notch Signaling for Carcinogenesis and Progression of Nonmelanoma Skin Cancer: Lessons Learned from Cancer Stem Cells, Tumor Angiogenesis, and Beyond

Since many decades, nonmelanoma skin cancer (NMSCs) is the most common malignancy worldwide. Basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) are the major types of NMSCs, representing approximately 70% and 25% of these neoplasias, respectively. Because of their continuously rising incidence rates, NMSCs represent a constantly increasing global challenge for healthcare, although they are in most cases nonlethal and curable (e.g., by surgery). While at present, carcinogenesis of NMSC is still not fully understood, the relevance of genetic and molecular alterations in several pathways, including evolutionary highly conserved Notch signaling, has now been shown convincingly. The Notch pathway, which was first developed during evolution in metazoans and that was first discovered in fruit flies (Drosophila melanogaster), governs cell fate decisions and many other fundamental processes that are of high relevance not only for embryonic development, but also for initiation, promotion, and progression of cancer. Choosing NMSC as a model, we give in this review a brief overview on the interaction of Notch signaling with important oncogenic and tumor suppressor pathways and on its role for several hallmarks of carcinogenesis and cancer progression, including the regulation of cancer stem cells, tumor angiogenesis, and senescence.

Genomic landscape and clonal architecture of mouse oral squamous cell carcinomas dictate tumour ecology

To establish whether 4-nitroquinoline N-oxide-induced carcinogenesis mirrors the heterogeneity of human oral squamous cell carcinoma (OSCC), we have performed genomic analysis of mouse tongue lesions. The mutational signatures of human and mouse OSCC overlap extensively. Mutational burden is higher in moderate dysplasias and invasive SCCs than in hyperplasias and mild dysplasias, although mutations in p53, Notch1 and Fat1 occur in early lesions. Laminin-α3 mutations are associated with tumour invasiveness and Notch1 mutant tumours have an increased immune infiltrate. Computational modelling of clonal dynamics indicates that high genetic heterogeneity may be a feature of those mild dysplasias that are likely to progress to more aggressive tumours. These studies provide a foundation for exploring OSCC evolution, heterogeneity and progression.

Molecular prediction of metastasis in cutaneous squamous cell carcinoma

PURPOSE OF REVIEW

Cutaneous squamous cell carcinoma (cSCC) is a highly prevalent malignancy frequently occurring on body surfaces chronically exposed to ultraviolet radiation. While a large majority of tumors remain localized to the skin and immediate subcutaneous tissue and are cured with surgical excision, a small subset of patients with cSCC will develop metastatic disease. Risk stratification for cSCC is performed using clinical staging systems, but given a high mutational burden and advances in targeted and immunotherapy, there is growing interest in molecular predictors of high-risk disease.

RECENT FINDINGS

Recent literature on the risk for metastasis in cSCC includes notable findings in genes involved in cell-cycle regulation, tumor suppression, tissue invasion and microenvironment, interactions with the host-immune system, and epigenetic regulation.

SUMMARY

cSCC is a highly mutated tumor with complex carcinogenesis. Regulators of tumor growth and local invasion are numerous and increasingly well-understood but drivers of metastasis are less established. Areas of importance include central system regulators (NOTCH, miRNAs), proteins involved in tissue invasion (podoplanin, E-cadherin), and targets of existing and emerging therapeutics (PD-1, epidermal growth factor receptor). Given the complexity of cSCC carcinogenesis, the use of machine learning algorithms and computational genomics may provide ultimate insight and prospective studies are needed to verify clinical relevance.

Cancer Stem Cells, Quo Vadis? The Notch Signaling Pathway in Tumor Initiation and Progression

The Notch signaling pathway regulates cell proliferation, cytodifferentiation and cell fate decisions in both embryonic and adult life. Several aspects of stem cell maintenance are dependent from the functionality and fine tuning of the Notch pathway. In cancer, Notch is specifically involved in preserving self-renewal and amplification of cancer stem cells, supporting the formation, spread and recurrence of the tumor. As the function of Notch signaling is context dependent, we here provide an overview of its activity in a variety of tumors, focusing mostly on its role in the maintenance of the undifferentiated subset of cancer cells. Finally, we analyze the potential of molecules of the Notch pathway as diagnostic and therapeutic tools against the various cancers.

Targeting cancer stem cell pathways for cancer therapy

Since cancer stem cells (CSCs) were first identified in leukemia in 1994, they have been considered promising therapeutic targets for cancer therapy. These cells have self-renewal capacity and differentiation potential and contribute to multiple tumor malignancies, such as recurrence, metastasis, heterogeneity, multidrug resistance, and radiation resistance. The biological activities of CSCs are regulated by several pluripotent transcription factors, such as OCT4, Sox2, Nanog, KLF4, and MYC. In addition, many intracellular signaling pathways, such as Wnt, NF-κB (nuclear factor-κB), Notch, Hedgehog, JAK-STAT (Janus kinase/signal transducers and activators of transcription), PI3K/AKT/mTOR (phosphoinositide 3-kinase/AKT/mammalian target of rapamycin), TGF (transforming growth factor)/SMAD, and PPAR (peroxisome proliferator-activated receptor), as well as extracellular factors, such as vascular niches, hypoxia, tumor-associated macrophages, cancer-associated fibroblasts, cancer-associated mesenchymal stem cells, extracellular matrix, and exosomes, have been shown to be very important regulators of CSCs. Molecules, vaccines, antibodies, and CAR-T (chimeric antigen receptor T cell) cells have been developed to specifically target CSCs, and some of these factors are already undergoing clinical trials. This review summarizes the characterization and identification of CSCs, depicts major factors and pathways that regulate CSC development, and discusses potential targeted therapy for CSCs.

Triptonide effectively suppresses gastric tumor growth and metastasis through inhibition of the oncogenic Notch1 and NF-κB signaling pathways

Gastric cancer ranks as the third leading cause of cancer-related death worldwide. The uncontrolled tumor growth and robust metastasis are key factors to cause the cancer patient death. Mechanistically, aberrant activation of Notch and NF-κB signaling pathways plays pivotal roles in the initiation and metastasis of gastric cancer. Despite great efforts have been made in recent decades, the effective drug against the advanced and metastatic gastric cancer is still lacking in the clinical setting. In this study, we found that triptonide, a small molecule (MW358) purified from the traditional Chinese medicinal herb Tripterygium wilfordii Hook F, effectively suppressed tumor growth and metastasis in xenograft mice without obvious toxicity at the doses we tested, resulting in potent anti-gastric cancer effect with low toxicity. Triptonide markedly inhibited human metastatic gastric cancer cell migration, invasion, proliferation, and tumorigenicity. Molecular mechanistic studies revealed that triptonide significantly reduced Notch1 protein levels in metastatic gastric cancer cells through degrading the oncogenic protein Notch1 via the ubiquitin-proteasome pathway. Consequently, the levels of Notch1 downstream proteins RBPJ, IKKα, IKKβ were significantly diminished, and nuclear factor-kappa B (NF-κB) phosphorylation was significantly reduced. Together, triptonide effectively suppresses gastric cancer growth and metastasis via inhibition of the oncogenic Notch1 and NF-κB signaling pathways. Our findings provide a new strategy and drug candidate for treatment of the advanced and metastatic gastric cancer.