5-Desmethylsinensetin isolated from Artemisia princeps suppresses the stemness of breast cancer cells via Stat3/IL-6 and Stat3/YAP1 signaling

Tumor microenvironment of cancer stem cells: Perspectives on cancer stem cell targeting

There are few tumor cell subpopulations with stem cell characteristics in tumor tissue, defined as cancer stem cells (CSCs) or cancer stem-like cells (CSLCs), which can reconstruct neoplasms with malignant biological behaviors such as invasiveness via self-renewal and unlimited generation. The microenvironment that CSCs depend on consists of various cellular components and corresponding medium components. Among these factors existing at a variety of levels and forms, cytokine networks and numerous signal pathways play an important role in signaling transduction. These factors promote or maintain cancer cell stemness, and participate in cancer recurrence, metastasis, and resistance. This review aims to summarize the recent molecular data concerning the multilayered relationship between CSCs and CSC-favorable microenvironments. We also discuss the therapeutic implications of targeting this synergistic interplay, hoping to give an insight into targeting cancer cell stemness for tumor therapy and prognosis.

Antitumor activity of 5-hydroxy-3',4',6,7-tetramethoxyflavone in glioblastoma cell lines and its antagonism with radiotherapy

5-Hydroxy-3',4',6,7-tetramethoxyflavone (TMF) is a plant-origin flavone known for its anti-cancer properties. In the present study, the cytotoxic effect of TMF was evaluated in the U87MG and T98G glioblastoma (GBM) cell lines. The effect of TMF on cell viability was assessed with trypan blue exclusion assay and crystal violet staining. In addition, flow cytometry was performed to examine its effect on the different phases of the cell cycle, and in vitro scratch wound assay assessed the migratory capacity of the treated cells. Furthermore, the effect of in vitro radiotherapy was also evaluated with a combination of TMF and radiation. In both cell lines, TMF treatment resulted in G0/G1 cell cycle arrest, reduced cell viability, and reduced cell migratory capacity. In contrast, there was an antagonistic property of TMF treatment with radiotherapy. These results demonstrated the antineoplastic effect of TMF in GBM cells in vitro, but the antagonistic effect with radiotherapy indicated that TMF should be further evaluated for its possible antitumor role post-radiotherapy.

Dihydroartemisinin increased the abundance of Akkermansia muciniphila by YAP1 depression that sensitizes hepatocellular carcinoma to anti-PD-1 immunotherapy

The effect of anti-programmed cell death 1 (anti-PD-1) immunotherapy is limited in patients with hepatocellular carcinoma (HCC). Yes-associated protein 1 (YAP1) expression increased in liver tumor cells in early HCC, and Akkermansia muciniphila abundance decreased in the colon. The response to anti-PD-1 treatment is associated with A. muciniphila abundance in many tumors. However, the interaction between A. muciniphila abundance and YAP1 expression remains unclear in HCC. Here, anti-PD-1 treatment decreased A. muciniphila abundance in the colon, but increased YAP1 expression in the tumor cells by mice with liver tumors in situ. Mechanistically, hepatocyte-specific Yap1 knockout (Yap1LKO) maintained bile acid homeostasis in the liver, resulting in an increased abundance of A. muciniphila in the colon. Yap1 knockout enhanced anti-PD-1 efficacy. Therefore, YAP1 inhibition is a potential target for increasing A. muciniphila abundance to promote anti-PD-1 efficacy in liver tumors. Dihydroartemisinin (DHA), acting as YAP1 inhibitor, increased A. muciniphila abundance to sensitize anti-PD-1 therapy. A. muciniphila by gavage increased the number and activation of CD8+ T cells in liver tumor niches during DHA treatment or combination with anti-PD-1. Our findings suggested that the combination anti-PD-1 with DHA is an effective strategy for liver tumor treatment.

STAT3 signaling in prostate cancer progression and therapy resistance: An oncogenic pathway with diverse functions

The categorization of cancers demonstrates that prostate cancer is the most common malignancy in men and it causes high death annually. Prostate cancer patients are diagnosed mainly via biomarkers such as PSA test and patients show poor prognosis. Prostate cancer cells rapidly diffuse into different parts of body and their metastasis is also a reason for death. Current therapies for prostate cancer patients include chemotherapy, surgery and radiotherapy as well as targeted therapy. The progression of prostate cancer cells is regulated by different factors that STAT3 signaling is among them. Growth factors and cytokines such as IL-6 can induce STAT3 signaling and it shows carcinogenic impact. Activation of STAT3 signaling occurs in prostate cancer and it promotes malignant behavior of tumor cells. Induction of STAT3 signaling increases glycolysis and proliferation of prostate cancer cells and prevents apoptosis. Furthermore, STAT3 signaling induces EMT mechanism in increasing cancer metastasis. Activation of STAT3 signaling stimulates drug resistance and the limitation of current works is lack of experiment related to role of STAT3 signaling in radio-resistance in prostate tumor. Calcitriol, capsazepine and β-elemonic are among the compounds capable of targeting STAT3 signaling and its inhibition in prostate cancer therapy. In addition to natural products, small molecules targeting STAT3 signaling have been developed in prostate cancer therapy.

Role of O-GlcNAcylation on cancer stem cells: Connecting nutrient sensing to cell plasticity

Tumor growth and metastasis can be promoted by a small sub-population of cancer cells, termed cancer stem-like cells (CSCs). While CSCs possess capability in self-renewing and differentiating, the hierarchy of CSCs during tumor growth is highly plastic. This plasticity in CSCs fate and function can be regulated by signals from the tumor microenvironment. One emerging pathway in CSCs that connects the alteration in microenvironment and signaling network in cancer cells is the hexosamine biosynthetic pathway (HBP). The final product of HBP, UDP-N-acetylglucosamine (UDP-GlcNAc), is utilized for glycosylating of membrane and secreted proteins, but also nuclear and cytoplasmic proteins by the post-translational modification O-GlcNAcylation. O-GlcNAcylation and its enzyme, O-GlcNAc transferase (OGT), are upregulated in nearly all cancers and been linked to regulate many cancer cell phenotypes. Recent studies have begun to connect OGT and O-GlcNAcylation to regulation of CSCs. In this review, we will discuss the emerging role of OGT and O-GlcNAcylation in regulating fate and plasticity of CSCs, as well as the potential in targeting OGT/O-GlcNAcylation in CSCs.

Dracunculin Inhibits Adipogenesis in Human Bone Marrow-Derived Mesenchymal Stromal Cells by Activating AMPK and Wnt/β-Catenin Signaling

Increased bone marrow adiposity is widely observed in patients with obesity and osteoporosis and reported to have deleterious effects on bone formation. Dracunculin (DCC) is a coumarin isolated from Artemisia spp. but, until now, has not been studied for its bioactive potential except antitrypanosomal activity. In this context, current study has reported the anti-adipogenic effect of DCC in human bone marrow-derived mesenchymal stromal cells (hBM-MSCs). DCC dose-dependently inhibited the lipid accumulation and expression of adipogenic transcription factors peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein α (C/EBPα) in hBM-MSCs induced to undergo adipogenesis. To elucidate its action mechanism, the effect of DCC on Wnt/β-catenin and AMPK pathways was examined. Results showed that DCC treatment activated Wnt/β-catenin signaling pathway via AMPK evidenced by increased levels of AMPK phosphorylation and Wnt10b expression after DCC treatment. In addition, DCC treated adipo-induced hBM-MSCs exhibited significantly increased nuclear levels of β-catenin compared with diminished nuclear PPARγ levels. In conclusion, DCC was shown to be able to hinder adipogenesis by activating the β-catenin via AMPK, providing potential utilization of DCC as a nutraceutical against bone marrow adiposity.