Dexamethasone inhibits stemness maintenance and enhances chemosensitivity of hepatocellular carcinoma stem cells by inducing deSUMOylation of HIF‑1α and Oct4

Phytochemistry of Genus Buxus and Pharmacology of Cyclovirobuxine D

BACKGROUND

Genus Buxus plants, commonly known as "boxwood", are widely distributed in China. The stems, branches, and leaves of the plant are traditionally used for rheumatism, toothache, chest pain, abdominal gas, and other diseases. However, an overview of the genus Buxus remains to be provided.

PURPOSE

To provide a scientific basis for the appropriate use and further research the recent advancements in the traditional usage, phytochemistry, and, pharmacology of Buxus.

STUDY DESIGN

Chemical composition and pharmacological correlation studies through a literature review.

METHODS

Between 1970 and 2023, the available data concerning Buxus was compiled from online scientific sources, such as Sci-Finder, PubMed, CNKI, Google Scholar, and the Chinese Pharmacopoeia. Plant names were verified from "The Plant List" (http://www.theplantlist.org/).

RESULTS

To date, 266 structurally diverse chemicals have been extracted and identified from the genus Buxus. Alkaloids constitute one of its primary bioactive phytochemicals. A summary of the channels of action of Cyclovirobuxine D on the cytotoxicity of a variety of cancers has been provided.

CONCLUSION

Numerous findings from contemporary phytochemical and pharmacological studies support the traditional use, facilitating its application. Further research is necessary to address various shortcomings, including the identification of the active ingredients and quality control of the genus Buxus.

Dexamethasone-tamoxifen combination exerts synergistic therapeutic effects in tamoxifen-resistance breast cancer cells

Tamoxifen (TAM) is a key player in estrogen receptor-positive (ER+) breast cancer (BC); however, ∼30% of patients experience relapse and a lower survival rate due to TAM resistance. TAM resistance was related to the over expression of SOX-2 gene, which is regulated by the E2F3 transcription factor in the Wnt signaling pathway. It was suggested that SOX-2 overexpression was suppressed by dexamethasone (DEX), a glucocorticoid commonly prescribed to BC patients. The aim of the present study is to explore the effect of combining DEX and TAM on the inhibition of TAM-resistant LCC-2 cells (TAMR-1) through modulating the E2F3/SOX-2-mediated Wnt signaling pathway. The effect of the combination therapy on MCF-7 and TAMR-1 cell viability was assessed. Drug interactions were analyzed using CompuSyn and SynergyFinder softwares. Cell cycle distribution, apoptotic protein expression, gene expression levels of SOX-2 and E2F3, and cell migration were also assessed. Combining DEX with TAM led to synergistic inhibition of TAMR-1 cell proliferation and migration, induced apoptosis, reduced SOX-2 and E2F3 expression and was also associated with S and G2-M phase arrest. Therefore, combining DEX with TAM may present an effective therapeutic option to overcome TAM resistance, by targeting the E2F3/SOX-2/Wnt signaling pathway, in addition to its anti-inflammatory effect.

Abnormal protein SUMOylation in liver disease: novel target for therapy

SUMOylation is an important protein post-translational modification (PTM) process, in which the small ubiquitin-like modifier (SUMO) protein covalently binds to the target protein and regulates stability, subcellular localization, and protein-protein interaction of the target protein. Protein SUMOylation exerts crucial regulatory function in the liver, and its abnormalities are associated with various liver-related disease processes. This review focuses on the biological functions of protein SUMOylation in liver-related diseases in recent years, summarizes the molecular mechanisms of SUMOylation in the replication of hepatitis viruses and the occurrence of hepatocellular carcinoma, and discusses the significance of SUMOylation in liver-related disorders, which is essential for understanding liver biological processes and formulating therapeutic strategies.

LINC00365 functions as a tumor suppressor by inhibiting HIF-1α-mediated glucose metabolism reprogramming in breast cancer

Long non-coding RNAs (lncRNAs) play an important role in regulating several physiological processes and have been implicated in several pathologies including cancer. LncRNAs have been found to regulate key cellular pathways involved in cancer development, and their aberrant expression plays critical roles in the onset or progression of disease. The role of lncRNAs in breast cancer (BC) has become a hot topic of research in recent years. We previously showed that LINC00365 inhibits BC survival. In the current study, based on the important role of energy metabolism and HIF-1α for tumor cell proliferation, we investigated the role and mechanism of the LINC00365/HIF-1α axis in affecting tumor growth through glycolysis using the breast cancer cell lines MCF-7 and HCC-1937. We found that LINC00365 inhibited BC cell proliferation. Furthermore, LINC00365 overexpression suppressed aerobic glycolysis in BC cells. RNA-sequencing identified hypoxia-inducible factor-1α (HIF-1α), which has been linked with glycolysis and upregulates glycolysis-related genes, as a potential target gene of LINC00365. Accordingly, we found that LINC00365 overexpression resulted in decreased expression of key glycolytic enzymes such as downstream hexokinase 2 (HK2), recombinant pyruvate kinase isozymes M2 (PKM2) and lactate dehydrogenase A (LDHA). Our results suggest that targeting LINC00365 may reverse the glucose metabolism pattern of BC and effectively inhibit BC survival both in vitro and in vivo.

A regenerable electrochemical sensor for electro-inactive cyclovirobuxine D detection in biological samples

Based on the pK_a determination of cyclovirobuxine D (CVB-D) using the method of potentiometry, we predicted the ionization state of CVB-D at physiological pH. Thus, by taking advantage of the ionization state and consequent non-covalent interactions between protonated CVB-D and deprotonated polymerized bromothymol blue (poly-BTB) under physiological conditions, we developed a simple and reusable electrochemical sensor that contains a poly-BTB/SWNT-modified electrode for electro-inactive CVB-D detection in biological fluids using poly-BTB as both the recognition unit and the electrochemical probe. Upon being immersed in the solution of CVB-D, the poly BTB-based electrode shows a current decrease due to the interaction-driven binding of CVB-D on the electrode surface. The current decrease in the electrochemical sensor toward CVB-D concentration shows a linear relationship in the dynamic ranges of 0.01-1 μM and 1-50 μM with a detection limit of 1.65 nM based on 3σ. The sensor can be easily regenerated through the removal of the binding of CVB-D from the electrode surface by highly negatively charged heparin, and it presents high repeatability with an RSD of less than 4.0% for seven measurements. In animal experiments, the electrochemical sensor was selective and sensitive for CVB-D determination in plasma and liver homogenates. The electrochemical sensor is readily accessible, robust, and cost-effective and holds good promise for more applications in biological and clinical fields associated with CVB-D using less technically demanding and simple operating procedures.

Protein sumoylation in normal and cancer stem cells

Stem cells with the capacity of self-renewal and differentiation play pivotal roles in normal tissues and malignant tumors. Whereas stem cells are supposed to be genetically identical to their non-stem cell counterparts, cell stemness is deliberately regulated by a dynamic network of molecular mechanisms. Reversible post-translational protein modifications (PTMs) are rapid and reversible non-genetic processes that regulate essentially all physiological and pathological process. Numerous studies have reported the involvement of post-translational protein modifications in the acquirement and maintenance of cell stemness. Recent studies underscore the importance of protein sumoylation, i.e., the covalent attachment of the small ubiquitin-like modifiers (SUMO), as a critical post-translational protein modification in the stem cell populations in development and tumorigenesis. In this review, we summarize the functions of protein sumoylation in different kinds of normal and cancer stem cells. In addition, we describe the upstream regulators and the downstream effectors of protein sumoylation associated with cell stemness. We also introduce the translational studies aiming at sumoylation to target stem cells for disease treatment. Finally, we propose future directions for sumoylation studies in stem cells.

Cancer Stem Cells and the Tumor Microenvironment: Targeting the Critical Crosstalk through Nanocarrier Systems

The physiological state of the tumor microenvironment (TME) plays a central role in cancer development due to multiple universal features that transcend heterogeneity and niche specifications, like promoting cancer progression and metastasis. As a result of their preponderant involvement in tumor growth and maintenance through several microsystemic alterations, including hypoxia, oxidative stress, and acidosis, TMEs make for ideal targets in both diagnostic and therapeutic ventures. Correspondingly, methodologies to target TMEs have been investigated this past decade as stratagems of significant potential in the genre of focused cancer treatment. Within targeted oncotherapy, nanomedical derivates-nanocarriers (NCs) especially-have emerged to present notable prospects in enhancing targeting specificity. Yet, one major issue in the application of NCs in microenvironmental directed therapy is that TMEs are too broad a spectrum of targeting possibilities for these carriers to be effectively employed. However, cancer stem cells (CSCs) might portend a solution to the above conundrum: aside from being quite heavily invested in tumorigenesis and therapeutic resistance, CSCs also show self-renewal and fluid clonogenic properties that often define specific TME niches. Further scrutiny of the relationship between CSCs and TMEs also points towards mechanisms that underly tumoral characteristics of metastasis, malignancy, and even resistance. This review summarizes recent advances in NC-enabled targeting of CSCs for more holistic strikes against TMEs and discusses both the current challenges that hinder the clinical application of these strategies as well as the avenues that can further CSC-targeting initiatives. Central role of CSCs in regulation of cellular components within the TME.

Mild Hypothermia Promotes Ischemic Tolerance and Survival of Neural Stem Cell Grafts by Enhancing Global SUMOylation

Cerebral infarct penumbra due to hypoxia and toxin accumulation is not conducive to the transplantation of neural stem cells (NSCs), although mild hypothermia can improve the local microenvironment of the ischemic penumbra and exert neuroprotective effects. However, insufficient understanding of the molecular mechanism by which mild hypothermia protects the brain limits widespread clinical application. This study evaluated the molecular mechanism of mild hypothermia-induced brain protection from the perspective of global protein small ubiquitin-like modifier (SUMO) modification, with the aim of improving NSC transplant survival rates in the penumbra to enhance neurological function. NSCs from neonatal rats were extracted to detect the effects of hypoxia and mild hypothermia on SUMOylation modification levels, cell stemness, and hypoxia-induced injury. Overexpression and knockdown of UBC9 in NSCs were used to evaluate their ability to maintain stemness and withstand hypoxic injury. Finally, a rat middle cerebral artery occlusion (MCAO) model was used to verify the effect of mild hypothermia treatment and UBC9 overexpression on neural function of NSCs following penumbra transplantation in rats. Results showed that hypoxia and mild hypothermia promoted both the SUMOylation modification and maintenance of NSC stemness. Overexpression of UBC9 enhanced the abilities of NSCs to maintain stemness and resist hypoxic injury, while UBC9 knockdown had the opposite effect. Following transplantation into the ischemic penumbra of MCAO model rats, mild hypothermia and Ubc9-overexpressing NSCs significantly reduced cerebral infarct areas and improved neurological function. In conclusion, this study demonstrated that global protein SUMOylation is an important molecular mechanism for NSCs to tolerate hypoxia, and mild hypothermia can further increase the degree of global SUMOylation to enhance the hypoxia tolerance of NSCs, which increases their survival during transplantation in situ and ability to perform nerve repair in the penumbra of cerebral infarction.

Dexamethasone promotes breast cancer stem cells in obese and not lean mice

Obesity is highly prevalent in breast cancer patients and is associated with increased recurrence and breast cancer-specific mortality. Glucocorticoids (GC) are used as an adjuvant in cancer treatment and are associated with promoting breast cancer metastasis through activation of stemness-related pathways. Therefore, we utilized the synergetic allograft E0771 breast cancer model to investigate if treatment with GCs had differential effects on promoting cancer stem cells in lean and diet-induced obese mice. Indeed, both lean mice treated with dexamethasone and obese mice with no treatment had no effect on the ex vivo colony-forming ability, mammosphere formation, or aldehyde dehydrogenase (ALDH) bright subpopulation. However, treatment of obese mice with dexamethasone resulted in a significant increase in ex vivo colony formation, mammosphere formation, ALDH bright subpopulation, and expression of pluripotency transcription factors. GC transcriptionally regulated genes were not altered in the dexamethasone-treated groups compared to treatment controls. In summary, these results provide initial evidence that obesity presents a higher risk of GC-induced cancer stemness via non-genomic GC signaling which is of potential translational significance.

SENP2 Reduces Hepatocellular Carcinoma Stemness and Improves Sorafenib Sensitivity Through Inactivating the AKT/GSK3β/CTNNB1 Pathway

Background

Small ubiquitin-like modifier specific peptidase 2 (SENP2) suppresses the progression and chemoresistance of several cancers, while few studies report its role in hepatocellular carcinoma (HCC). This study aimed to evaluate the effect of SENP2 on stemness, sorafenib sensitivity, and downstream pathway in HCC, with validation of its molecular mechanisms by compensation experiment.

Methods

SENP2 was regulated by plasmid transfection; meanwhile, in a compensation experiment, protein kinase B (AKT) was activated by SC79 treatment and β-catenin (CTNNB1) was overexpressed by plasmid transfection. After modification, sorafenib sensitivity was detected by cell counting kit-8 assay; stemness was evaluated by CD133⁺ cell proportion and sphere formation assay.

Results

SENP2 was decreased in HCC cell lines (including Hep3B, Li7, and Huh7) compared with normal human liver epithelial cell lines, which was further reduced in HCC stem cells than in normal HCC cells. Subsequently, SENP2 overexpression inhibited CD133⁺ cell proportion, decreased sphere formation ability, promoted sorafenib sensitivity, suppressed AKT and glycogen synthase kinase-3β (GSK3β) phosphorylation, and reduced CTNNB1 expression in Huh7 and Hep3B cells, while SENP2 knockdown showed the reverse effects. The following compensation experiment revealed that activating AKT or overexpressing CTNNB1 promoted CD133⁺ cell proportion and sphere formation ability but suppressed sorafenib sensitivity in Huh7 and Hep3B cells. Moreover, activating AKT or overexpressing CTNNB1 attenuated the effect of SENP2 overexpression on stemness and sorafenib sensitivity in Huh7 and Hep3B cells.

Conclusion

SENP2 suppresses HCC stemness and increases sorafenib sensitivity through inactivating the AKT/GSK3β/CTNNB1 signaling pathway.

The Role of Protein SUMOylation in Human Hepatocellular Carcinoma: A Potential Target of New Drug Discovery and Development

Simple Summary

The small ubiquitin-like modifier is a highly conserved post-translational modification protein, mainly found in eukaryotes. Recently, studies have shown that SUMOylation promotes the development of liver cancer. This article summarises the recent literature on SUMOylation and Hepatocellular carcinoma (HCC). The mechanism of SUMOs in liver cancer cells was described. It also shows the potential of SUMO as a therapeutic target for liver cancer. At the same time, this article also enumerates the practical application in clinical, developing progress and future direction of HCC in clinical practice.

Abstract

Small ubiquitin-like modifier (SUMO) is a highly conserved post-translational modification protein, mainly found in eukaryotes. They are widely expressed in different tissues, including the liver. As an essential post-translational modification, SUMOylation is involved in many necessary regulations in cells. It plays a vital role in DNA repair, transcription regulation, protein stability and cell cycle progression. Increasing shreds of evidence show that SUMOylation is closely related to Hepatocellular carcinoma (HCC). The high expression of SUMOs in the inflammatory hepatic tissue may lead to the carcinogenesis of HCC. At the same time, SUMOs will upregulate the proliferation and survival of HCC, migration, invasion and metastasis of HCC, tumour microenvironment as well as drug resistance. This study reviewed the role of SUMOylation in liver cancer. In addition, it also discussed natural compounds that modulate SUMO and target SUMO drugs in clinical trials. Considering the critical role of SUMO protein in the occurrence of HCC, the drug regulation of SUMOylation may become a potential target for treatment, prognostic monitoring and adjuvant chemotherapy of HCC.