Cyclin A/Cdk2 regulates Cdh1 and claspin during late S/G2 phase of the cell cycle

The molecular mechanism of action for the potent antitumor component extracted using supercritical fluid extraction from Croton crassifolius root

ETHNOPHARMACOLOGICAL RELEVANCE

The root of Croton crassifolius has been used as a traditional Chinese medicine (TCM), called Radix Croton Crassifolius, and commonly known as "Ji Gu Xiang" in Chinese. Its medicinal value has been recorded in several medical books or handbooks, such as "Sheng Cao Yao Xing Bei Yao", "Ben Cao Qiu Yuan" and "Zhong Hua Ben Cao". It has been traditional employed for treating sore throat, stomach-ache, rheumatism and cancer.

AIM OF THE STUDY

At present, there are limited studies on the evaluation of low-polarity extracts of roots in C. crassifolius. Consequently, the aim of this study was to evaluate the antitumor effect of the low-polarity extract of C. crassifolius root.

MATERIALS AND METHODS

Extracts were obtained by supercritical fluid extraction. The extracts were tested for antitumor effects in vitro on several cancer cell lines. A CCK-8 kit was used for further analysis of cell viability. A flow cytometer and propidium iodide staining were used to evaluate the cell cycle and apoptosis. Hoechst staining, JC-1 staining and the fluorescence probe DCFH-DA were used to evaluate apoptotic cells. Molecular mechanisms of action were analyzed by quantitative RT‒PCR and Western blotting. Immunohistochemistry was used for the evaluation of xenograft tumors in male BALB/c mice. Finally, molecular docking was employed to predict the bond between the desired bioactive compound and molecular targets.

RESULTS

Eleven diterpenoids were isolated from low-polarity C. crassifolius root extracts. Among the compounds, chettaphanin II showed the strongest activity (IC50 = 8.58 μM) against A549 cells. Evaluation of cell viability and the cell cycle showed that Chettaphanin II reduced A549 cell proliferation and induced G2/M-phase arrest. Chttaphanin II significantly induced apoptosis in A549 cells, which was related to the level of apoptosis-related proteins. The growth of tumor tissue was significantly inhibited by chettaphanin II in experiments performed on naked mice. The antitumor mechanism of chettaphanin II is that it can obstruct the mTOR/PI3K/Akt signaling pathway in A549 cells. Molecular docking established that chettaphanin II could bind to the active sites of Bcl-2 and Bax.

CONCLUSIONS

Taken together, the natural diterpenoid chettaphanin II was identified as the major antitumor active component, and its potential for developing anticancer therapies was demonstrated for the first time by antiproliferation evaluation in vitro and in vivo.

Cymbopogon proximus phytochemicals induce S-phase arrest in A549 lung cancer cell lines via CDK2/cyclin A2 inhibition: gas chromatography-mass spectrometry and molecular docking analyses

Cymbopogon proximus comprises several phytoconstituent classes that are reported to possess anticancer activity; however, studies on the anticancer potentials of the plant are lacking. C. proximus was extracted using solvents with increasing polarity. In-vitro cytotoxic activity of C. proximus extracts was examined against liver (HepG2), lung (A549), prostate (PC3), and bone (MG63) cell lines using MTT assay in comparison to doxorubicin. Flow cytometry was used to analyze the cell cycle for identification of the phase of inhibition. Chemical composition of the most active fraction was examined using the GC/MS technique. Molecular docking was used to explore the mechanism of cytotoxicity against A549, and the results were confirmed by Western blot analysis. Petroleum ether fraction was the highly effective fraction against A549 with IC50 = 14.02 ± 2.79. GC/MS analysis of Pet.Eth led to the identification of nine compounds in unsaponifiable matter and 27 components in the saponifiable fraction. Di-N-octyl phthalate, 3-β-hydroxylean-11.13(18)-dien-30-oic acid methyl ester, elemol hydrocarbons, linoelaidic acid and linoleic acid demonstrated the lowest docking binding scores and similar binding modes against CDK2 as compared to that attained by the native ligand R-Roscovitine "CDK2 ATP inhibitor". Western blot analysis demonstrated that CDK2/cyclinA2 protein expression has been suppressed in A549 cell lines by Pet.Eth fraction.

Exploring the role of pyroptosis in the pathogenicity of heart disease

Cell death is an essential cellular mechanism that ensures quality control and whole-body homeostasis. Various modes of cell death have been studied and detailed. Unbalanced cell death can lead to uncontrolled cell proliferation (i.e., tumors) or excessive loss of cells (i.e., ischemia injury tissue loss). Thus, it is imperative for modes of cell death to be balanced and controlled. Here, we will focus on a recent mode of cell death called pyroptosis. While extensive studies have shown the role of this route of cell death in macrophages and monocytes, evidence for pyroptosis have expanded to encompass other pathologies, including cancer and cardiac diseases. Herein, we provide a brief review on pyroptosis and discuss current gaps in knowledge and scientific advances in cardiac pyroptosis in recent years. Lastly, we provide conclusions and prospective on the relevance to various cardiac diseases.

Centrosomes and associated proteins in pathogenesis and treatment of breast cancer

Breast cancer is the most prevalent malignancy among women worldwide. Despite significant advances in treatment, it remains one of the leading causes of female mortality. The inability to effectively treat advanced and/or treatment-resistant breast cancer demonstrates the need to develop novel treatment strategies and targeted therapies. Centrosomes and their associated proteins have been shown to play key roles in the pathogenesis of breast cancer and thus represent promising targets for drug and biomarker development. Centrosomes are fundamental cellular structures in the mammalian cell that are responsible for error-free execution of cell division. Centrosome amplification and aberrant expression of its associated proteins such as Polo-like kinases (PLKs), Aurora kinases (AURKs) and Cyclin-dependent kinases (CDKs) have been observed in various cancers, including breast cancer. These aberrations in breast cancer are thought to cause improper chromosomal segregation during mitosis, leading to chromosomal instability and uncontrolled cell division, allowing cancer cells to acquire new genetic changes that result in evasion of cell death and the promotion of tumor formation. Various chemical compounds developed against PLKs and AURKs have shown meaningful antitumorigenic effects in breast cancer cells in vitro and in vivo. The mechanism of action of these inhibitors is likely related to exacerbation of numerical genomic instability, such as aneuploidy or polyploidy. Furthermore, growing evidence demonstrates enhanced antitumorigenic effects when inhibitors specific to centrosome-associated proteins are used in combination with either radiation or chemotherapy drugs in breast cancer. This review focuses on the current knowledge regarding the roles of centrosome and centrosome-associated proteins in breast cancer pathogenesis and their utility as novel targets for breast cancer treatment.

Lappaol F regulates the cell cycle by activating CDKN1C/p57 in human colorectal cancer cells

CONTEXT

Lappaol F (LAF), a natural lignan from Arctium lappa Linné (Asteraceae), inhibits tumor cell growth in vitro and in vivo. The underlying mechanism involves the suppression of the Yes-associated protein. However, the specific role of LAF in cell cycle regulation remains unknown.

OBJECTIVE

This study determined the molecular mechanism by which LAF regulates cell cycle progression.

MATERIALS AND METHODS

Various colon cancer cell lines (SW480, HCT15, and HCT116) were treated with LAF (25, 50, and 75 μmol/L) for 48 h. The effects of LAF on cell proliferation and cell cycle were determined using sulforhodamine B and flow cytometry assays. Differentially expressed proteins (DEPs) were identified using quantitative proteomics. Bioinformatic analysis of DEPs was conducted via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Expression levels of DEPs in the cell cycle pathway were analyzed using RT-qPCR and western blotting.

RESULTS

LAF suppressed the proliferation of SW480, HCT15, and HCT116 cells (IC₅₀ 47.1, 51.4, and 32.8 μmol/L, respectively) and induced cell cycle arrest at the S phase. A total of 6331 proteins were identified and quantified, of which 127 were differentially expressed between the LAF-treated and untreated groups. GO and KEGG enrichment analyses revealed that DEPs mainly participated in the cell cycle. CDKN1C/p57 showed the most significant differential expression, with the highest fold-change (3.155-fold). Knockdown of CDKN1C/p57 attenuated the S phase cell cycle arrest and proliferation inhibition induced by LAF.

CONCLUSION

LAF exerts antitumor effects via S phase arrest by activating CDKN1C/p57 in colorectal cancer cells.

Pyroptosis: shedding light on the mechanisms and links with cancers

Pyroptosis, a novel form of programmed cell death (PCD) discovered after apoptosis and necrosis, is characterized by cell swelling, cytomembrane perforation and lysis, chromatin DNA fragmentation, and the release of intracellular proinflammatory contents, such as Interleukin (IL) 8, IL-1β, ATP, IL-1α, and high mobility group box 1 (HMGB1). Our understanding of pyroptosis has increased over time with an increase in research on the subject: gasdermin-mediated lytic PCD usually, but not always, requires cleavage by caspases. Moreover, new evidence suggests that pyroptosis induction in tumor cells results in a strong inflammatory response and significant cancer regression, which has stimulated great interest among scientists for its potential application in clinical cancer therapy. It's worth noting that the side effects of chemotherapy and radiotherapy can be triggered by pyroptosis. Thus, the intelligent use of pyroptosis, the double-edged sword for tumors, will enable us to understand the genesis and development of cancers and provide potential methods to develop novel anticancer drugs based on pyroptosis. Hence, in this review, we systematically summarize the molecular mechanisms of pyroptosis and provide the latest available evidence supporting the antitumor properties of pyroptosis, and provide a summary of the various antitumor medicines targeting pyroptosis signaling pathways.

β-catenin inhibitor ICG-001 suppress cell cycle progression and induce autophagy in endometrial cancer cells

The incidence of endometrial cancer has been rising in recent years. Gene mutation and high protein expression of β-catenin are commonly detected in endometrioid endometrial cancer. ICG-001 is a β-catenin inhibitor via blocking the complex formation of β-catenin and cAMP response element-binding protein (CREB)-binding protein (CBP). This study aims to investigate the effect of ICG-001 on endometrial cancer inhibition. First, endometrial carcinoma patient-derived xenograft (PDX)-derived organoids and primary cells were used to verify the inhibiting ability of ICG-001 on endometrial cancer. Furthermore, endometrial cancer cell lines were used to investigate the anticancer mechanism of ICG-001. Using MTT assay and tumor spheroid formation assay, ICG-001 significantly reduced the cell viability of HEC-59 and HEC-1A cells. ICG-001 enhanced cisplatin-mediated cytotoxicity. ICG-001 decreased cancer stem cell sphere formation. ICG-001 decreased the protein expressions of CD44, hexokinase 2 (HK2), and cyclin A. ICG-001 lowered the cell cycle progression by flow cytometer analysis. Autophagy, but no apoptosis, was activated by ICG-001 in endometrial cancer cells. Autophagy inhibition by ATG5 silencing enhanced ICG-001-mediated suppression of cell viability, tumor spheroid formation, and protein expression of cyclin A and CD44. This study clarified the mechanism and revealed the clinical potential of ICG-001 against endometrial cancer.

A Comprehensive Review of Natural Products as Therapeutic or Chemopreventive Agents against Head and Neck Squamous Cell Carcinoma Cells Using Preclinical Models

Head and neck squamous cell carcinoma (HNSCC) is a type of cancer that arises from the epithelium lining of the oral cavity, hypopharynx, oropharynx, and larynx. Despite the advancement of current treatments, including surgery, chemotherapy, and radiotherapy, the overall survival rate of patients afflicted with HNSCC remains poor. The reasons for these poor outcomes are due to late diagnoses and patient-acquired resistance to treatment. Natural products have been extensively explored as a safer and more acceptable alternative therapy to the current treatments, with numerous studies displaying their potential against HNSCC. This review highlights preclinical studies in the past 5 years involving natural products against HNSCC and explores the signaling pathways altered by these products. This review also addresses challenges and future directions of natural products as chemotherapeutic and chemoprevention agents against HNSCC.

Anticancer effect of involucrasin A on colorectal cancer cells by modulating the Akt/MDM2/p53 pathway

Colorectal cancer (CRC) is the second leading cause of cancer mortality worldwide; however, there is still a lack of effective clinical anti-CRC agents. Naturally-occurring compounds have been considered a potentially valuable source of new antitumorigenic agents. Involucrasin A, a novel natural molecule, was isolated from Shuteria involucrata (Wall.) Wight & Arn by our team. In the present study, the anticancer activity of involucrasin A in HCT-116 CRC cells was evaluated. Firstly, the anti-proliferative effect of involucrasin A on HCT-116 cells was analyzed by sulforhodamine B and colony formation assays. The results revealed that involucrasin A exhibited a potent inhibitory effect on HCT-116 CRC cell proliferation in vitro. Subsequently, flow cytometry and western blotting indicated that involucrasin A induced apoptosis and upregulated the expression levels of apoptosis-related proteins, such as cleaved-caspase 6 and cleaved-caspase 9, in a dose-dependent manner. Mechanistically, involucrasin A significantly inhibited the phosphorylation of Akt and murine double minute 2 homologue (MDM2), which resulted in increased intracellular levels of p53. This was reversed by exogenous expression of the constitutively active form of Akt. Similarly, either knocking out p53 or knocking down Bax abrogated involucrasin A-induced proliferation inhibition and apoptosis. Together, the present study indicated that involucrasin A exerts antitumorigenic activities via modulating the Akt/MDM2/p53 pathway in HCT-116 CRC cells, and it is worthy of further exploration in preclinical and clinical trials.

Exploring the role of pyroptosis in shaping the tumor microenvironment of colorectal cancer by bulk and single-cell RNA sequencing

BACKGROUND

Emerging studies have shown that pyroptosis plays a non-negligible role in the development and treatment of tumors. However, the mechanism of pyroptosis in colorectal cancer (CRC) remains still unclear. Therefore, this study investigated the role of pyroptosis in CRC.

METHODS

A pyroptosis-related risk model was developed using univariate Cox regression and LASSO Cox regression analyses. Based on this model, pyroptosis-related risk scores (PRS) of CRC samples with OS time > 0 from Gene Expression Omnibus (GEO) database and The Cancer Genome Atlas (TCGA) database were calculated. The abundance of immune cells in CRC tumor microenvironment (TME) was predicted by single-sample gene-set enrichment analysis (ssGSEA). Then, the responses to chemotherapy and immunotherapy were predicted by pRRophetic algorithm, the tumor immune dysfunction and exclusion (TIDE) and SubMap algorithms, respectively. Moreover, the Cancer Therapeutics Response Portal (CTRP) and PRISM Repurposing dataset (PRISM) were used to explore novel drug treatment strategies of CRC. Finally, we investigated pyroptosis-related genes in the level of single-cell and validated the expression levels of these genes between normal and CRC cell lines by RT-qPCR.

RESULTS

Survival analysis showed that CRC samples with low PRS had better overall survival (OS) and progression-free survival (PFS). CRC samples with low PRS had higher immune-related gene expression and immune cell infiltration than those with high PRS. Besides, CRC samples with low PRS were more likely to benefit from 5-fluorouracil based chemotherapy and anti-PD-1 immunotherapy. In novel drug prediction, some compounds such as C6-ceramide and noretynodrel, were inferred as potential drugs for CRC with different PRS. Single-cell analysis revealed pyroptosis-related genes were highly expressed in tumor cells. RT-qPCR also demonstrated different expression levels of these genes between normal and CRC cell lines.

CONCLUSIONS

Taken together, this study provides a comprehensive investigation of the role of pyroptosis in CRC at the bulk RNA sequencing (RNA-seq) and single-cell RNA sequencing (scRNA-seq) levels, advances our understanding of CRC characteristics, and guides more effective treatment regimens.

Inhibitors of Jumonji C domain-containing histone lysine demethylases overcome cisplatin and paclitaxel resistance in non-small cell lung cancer through APC/Cdh1-dependent degradation of CtIP and PAF15

The Jumonji C domain-containing family of histone lysine demethylases (Jumonji KDMs) have emerged as promising cancer therapy targets. These enzymes remove methyl groups from various histone lysines and, in turn, regulate processes including chromatin compaction, gene transcription, and DNA repair. Small molecule inhibitors of Jumonji KDMs have shown promise in preclinical studies against non-small cell lung cancer (NSCLC) and other cancers. However, how these inhibitors influence cancer therapy responses and/or DNA repair is incompletely understood. In this study, we established cell line and PDX tumor model systems of cisplatin and paclitaxel-resistant NSCLC. We showed that resistant cells and tumors express high levels of Jumonji-KDMs. Knockdown of individual KDMs or treatment with a pan-Jumonji KDM inhibitor sensitized the cells and tumors to cisplatin and paclitaxel and blocked NSCLC in vivo tumor growth. Mechanistically, we found inhibition of Jumonji-KDMs triggers APC/Cdh1-dependent degradation of CtIP and PAF15, two DNA repair proteins that promote repair of cisplatin and paclitaxel-induced DNA lesions. Knockdown of CtIP and PAF15 sensitized resistant cells to cisplatin, indicating their degradation when Jumonji KDMs are inhibited contributes to cisplatin sensitivity. Our results support the idea that Jumonji-KDMs are a targetable barrier to effective therapy responses in NSCLC. Inhibition of Jumonji KDMs increases therapy (cisplatin/paclitaxel) sensitivity in NSCLC cells, at least in part, by promoting APC/Cdh1-dependent degradation of CtIP and PAF15.

Cuproptosis associated genes affect prognosis and tumor microenvironment infiltration characterization in lung adenocarcinoma

Cuproptosis, a newly discovered mechanism of programmed cell death, is important for detailing the metabolic aspects of cancer progression and thereby guiding cancer therapy. An exciting era of translational medicine has led to the rapid development of countless immunotherapeutic strategies. The existing successful cancer immunotherapies have sparked new hope for patients with solid and hematologic malignancies. Hence, it is important to characterize the link between the cuproptosis process and the immunity status in the tumor microenvironment (TME) in Lung Adenocarcinoma (LUAD), which may be able to predict patient's prognosis. In this study, we systematically assessed 10 cuproptosis-associated genes (CAGs) and comprehensively characterized the relationship between cuproptosis and the molecular characteristics and immune cell infiltration of tumor tissue, prognosis and clinical treatment of patients. Subsequently, the CAG_score for predicting overall survival (OS) was established and its reliable predictive ability in LUAD patients was confirmed. Next, we created a highly reliable nomogram to facilitate the clinical viability of the CAG_score. The low CAG_score group, with lower immune cell infiltration, and mutation burden, had a significantly superior OS, which was associated with a better response to immunotherapy. The present study revealed that cuproptosis play a significant role in TME regulation in LUAD. Collectively, we identified a prognostic CAGs-related signature for LUAD patients. This signature may contribute to clarifying the characteristics of TME and enable the exploration of more potent immunotherapy strategies.

Phytochemical Profiles, Antioxidant Activity and Antiproliferative Mechanism of Rhodiola rosea L. Phenolic Extract

The phenolic profiles, antioxidant activity, antiproliferative property and the underlying molecular mechanisms of cell apoptosis of Rhodiola rosea free phenolic (RFE) were analyzed in this work. Overall, Rhodiola rosea rhizome phenolic extract (RE) contained Rhodiola rosea rhizome free phenolic extract (RFE) and Rhodiola rosea rhizome bound phenolic extract (RBE). Compared with RBE, RFE contained higher phenolic contents and possessed stronger antioxidant activity. High-performance liquid chromatography (HPLC) results demonstrated that the main phenolics of were epigallocatechin (EGC), epigallocatechin gallate (EGCG), gallic acid (GA) and catechin. Gas chromatography–mass spectrometry (GC-MS) analysis found that Rhodiola rosea L. was rich in volatile phytochemicals. In addition, many types of vitamin E and a few kinds of carotenoids were found in Rhodiola rosea. In addition, the main compounds in RFE (GA, EGC, EGCG) and RFE all exhibited excellent antiproliferative activity, indicating the antiproliferative activity of RFE was partly attributed to the synergy effects of the main compounds. Further study confirmed that RFE could block 16.99% of HepG2 cells at S phase and induce 20.32% programmed cell death compared with the control group. Specifically, RFE dose-dependently induced cell apoptosis and cell cycle arrest via modulating the p53 signaling pathway including up-regulation of the expression of p53 and Bax while down-regulation of the Bcl-2, cyclin D1 and CDK4 levels. Therefore, RFE exhibited the potential of being developed as an auxiliary antioxidant and a therapeutic agent for cancer.

What Role Does Pyroptosis Play in Cancer?

Background

Pyroptosis has been attracting much attention recently. We have briefly compared its differences and similarities with other programmed deaths and the process of its study. With further exploration of the caspase family, including caspase-1/3/4/5/8/11, new insights into the molecular pathways of action of pyroptosis have been gained. It is also closely related to the development of many cancers, which at the same time provides us with new ideas for the treatment of cancer.

Scope of Review

We describe what is known regarding the impact of pyroptosis on anticancer immunity and give insight into the potential of harnessing pyroptosis as a tool and applying it to novel or existing anticancer strategies.

Major Conclusions

Pyroptosis, a caspase-dependent cell death, causes pore formation, cell swelling, rupture of the plasma membrane, and release of all intracellular contents. The role of pyroptosis in cancer is an extremely complex issue. There is growing evidence that tumor pyroptosis has anti-tumor and pro-tumor roles. It should be discussed in different cancer periods according to the characteristics of cancer occurrence and development. In cancer treatment, pyroptosis provides us with some potential new targets. For the existing drugs, the study of pyroptosis also helps us make better use of existing drugs for anticancer treatment. Immunotherapy is a hot research direction in the field of cancer treatment.

Duck hepatitis A virus type 1 mediates cell cycle arrest in the S phase

Background

Duck hepatitis A virus type 1 (DHAV-1) is one of the most serious pathogens endangering the duck industry. However, there are few studies on the regulation of the cell cycle by DHAV-1.

Methods

In this study, flow cytometry was applied to analyze the effect of DHAV-1 infection on the cell cycle of duck embryo fibroblasts (DEFs). Subsequently, we analyzed the effects of cell cycle phases on DHAV-1 replication by real-time reverse transcriptase quantitative PCR (real-time RT-qPCR).

Results

Flow cytometry data analysis found that DEFs in the S phase increased by 25.85% and 54.21% at 24 h and 48 h after DHAV-1 infection, respectively. The levels of viral RNA detected by real-time RT-qPCR were higher in the DEFs with synchronization in the S phase or G0/G1 phase than in the control group. However, there was no difference in viral copy number between the G2/M phase arrest and control groups. In addition, non-structural protein 3D of DHAV-1 significantly increased cells in the S phase, indicating that 3D protein is one of the reasons for the cell cycle arrest in the S phase.

Conclusions

In summary, DHAV-1 infection induces the cell cycle arrest of DEFs in the S phase. Both S phase and G0/G1 phase synchronization facilitate the replication of DHAV-1, and 3D protein is one of the reasons for the S phase arrest.

Identification of 3-(piperazinylmethyl)benzofuran derivatives as novel type II CDK2 inhibitors: design, synthesis, biological evaluation, and in silico insights

In the current work, a hybridisation strategy was adopted between the privileged building blocks, benzofuran and piperazine, with the aim of designing novel CDK2 type II inhibitors. The hybrid structures were linked to different aromatic semicarbazide, thiosemicarbazide, or acylhydrazone tails to anchor the designed inhibitors onto the CDK2 kinase domain. The designed compounds showed promising CDK2 inhibitory activity. Compounds 9h, 11d, 11e and 13c showed potent inhibitory activity (IC₅₀ of 40.91, 41.70, 46.88, and 52.63 nM, respectively) compared to staurosporine (IC₅₀ of 56.76 nM). Moreover, benzofurans 9e, 9h, 11d, and 13b showed promising antiproliferative activities towards different cancer cell lines, and non-significant cytotoxicity on normal lung fibroblasts MRC-5 cell line. Furthermore, a cell cycle analysis as well as Annexin V-FITC apoptosis assay on Panc-1 cell line were performed. Molecular docking simulations were performed to explore the ability of target benzofurans to adopt the common binding pattern of CDK2 type II inhibitors.

Application of Regulatory Cell Death in Cancer: Based on Targeted Therapy and Immunotherapy

The development of cancer treatment methods is constantly changing. For common cancers, our treatment methods are still based on conventional treatment methods, such as chemotherapy, radiotherapy, and targeted drug therapy. Nevertheless, the emergence of tumor resistance has a negative impact on treatment. Regulated cell death is a gene-regulated mode of programmed cell death. After receiving specific signal transduction, cells change their physical and chemical properties and the extracellular microenvironment, resulting in structural destruction and decomposition. As research accumulates, we now know that by precisely inducing specific cell death patterns, we can treat cancer with less collateral damage than other treatments. Many newly discovered types of RCD are thought to be useful for cancer treatment. However, some experimental results suggest that some RCDs are not sensitive to cancer cell death, and some may even promote cancer progression. This review summarizes the discovered types of RCDs, reviews their clinical efficacy in cancer treatment, explores their anticancer mechanisms, and discusses the feasibility of some newly discovered RCDs for cancer treatment in combination with the immune and tumor microenvironment.

Identification of 20(S)-Ginsenoside Rh2 as a Potential EGFR Tyrosine Kinase Inhibitor

As the main active ingredients of Panax ginseng, ginsenosides possess numerous bioactivities. Epidermal growth factor receptor (EGFR) was widely used as a valid target in anticancer therapy. Herein, the EGFR targeting activities of 20(S)-ginsenoside Rh2 (20(S)-Rh2) and the relationship of their structure-activity were investigated. Homogeneous time-resolved fluorescence assay showed that 20(S)-Rh2 significantly inhibited the activity against EGFR kinase. 20(S)-Rh2 was confirmed to effectively inhibited cell proliferation in a dose-dependent manner by MTT assay. Furthermore, quantitative real-time PCR and western blotting analysis revealed that 20(S)-Rh2 inhibited A549 cells growth via the EGFR-MAPK pathway. Meanwhile, 20(S)-Rh2 could promote cell apoptosis, block cell cycle, and reduce cell migration of A549 cells, respectively. In silico, the result suggested that both hydrophobic interactions and hydrogen-bonding interactions could contribute to stabilize their binding. Molecular dynamics simulation showed that the side chain sugar moiety of 20(S)-Rh2 was too flexible to be fixed at the active site of EGFR. Collectively, these findings suggested that 20(S)-Rh2 might serve as a potential EGFR tyrosine kinase inhibitor.

Novel oxindole/benzofuran hybrids as potential dual CDK2/GSK-3β inhibitors targeting breast cancer: design, synthesis, biological evaluation, and in silico studies

The serine/threonine protein kinases CDK2 and GSK-3β are key oncotargets in breast cancer cell lines, therefore, in the present study three series of oxindole-benzofuran hybrids were designed and synthesised as dual CDK2/GSK-3β inhibitors targeting breast cancer (5a-g, 7a-h, and 13a-b). The N1 -unsubstituted oxindole derivatives, series 5, showed moderate to potent activity on both MCF-7 and T-47D breast cancer cell lines. Compounds 5d-f showed the most potent cytotoxic activity with IC50 of 3.41, 3.45 and 2.27 μM, respectively, on MCF-7 and of 3.82, 4.53 and 7.80 μM, respectively, on T-47D cell lines, in comparison to the used reference standard (staurosporine) IC50 of 4.81 and 4.34 μM, respectively. On the other hand, the N1 -substituted oxindole derivatives, series 7 and 13, showed moderate to weak cytotoxic activity on both breast cancer cell lines. CDK2 and GSK-3β enzyme inhibition assay of series 5 revealed that compounds 5d and 5f are showing potent dual CDK2/GSK-3β inhibitory activity with IC50 of 37.77 and 52.75 nM, respectively, on CDK2 and 32.09 and 40.13 nM, respectively, on GSK-3β. The most potent compounds 5d-f caused cell cycle arrest in the G2/M phase in MCF-7 cells inducing cell apoptosis because of the CDK2/GSK-3β inhibition. Molecular docking studies showed that the newly synthesised N1 -unsubstituted oxindole hybrids have comparable binding patterns in both CDK2 and GSK-3β. The oxindole ring is accommodated in the hinge region interacting through hydrogen bonding with the backbone CO and NH of the key amino acids Glu81 and Leu83, respectively, in CDK2 and Asp133 and Val135, respectively, in GSK-3β. Whereas, in series 7 and 13, the N1 -substitutions on the oxindole nucleus hinder the compounds from achieving these key interactions with hinge region amino acids what rationalises their moderate to low anti-proliferative activity.

Near-infrared light triggered multi-hit therapeutic nanosystem for tumor specific photothermal effect amplified signal pathway regulation and ferroptosis

The high therapeutic resistance of tumor is the primary cause behind tumor recurrence and incurability. In recent years, scientists have devoted themselves to find a variety of treatments to solve this problem. Herein, we propose a multi-hit strategy that is based on the biodegradable hollow mesoporous Prussian blue (HMPB)-based nanosystem for tumor-specific therapy that encapsulated the critical heat shock protein 90 (HSP90) inhibitor 17-dimethylamino-ethylamino-17-demethoxydeldanamycin (17-DMAG). The nanosystem was further modified using thermotropic phase transition material star-PEG-PCL (sPP) and hyaluronic acid (HA), which offers near infrared light (NIR) responsive release characteristic, as well as enhanced tumor cell endocytosis. Upon cell internalization of 17-DMAG-HMPB@sPP@HA and under 808 nm laser irradiation, photothermal-conversion effect of HMPB directly kills cells using hyperthermia, which further causes phase transition of sPP to trigger release of 17-DMAG, inhibits HSP90 activity and blocks multiple signaling pathways, including cell cycle, Akt and HIF pathways. Additionally, the down-regulation of GPX4 protein expression by 17-DMAG and the release of ferric and ferrous ions from gradual degradation of HMPB in the endogenous mild acidic microenvironment in tumors promoted the occurrence of ferroptosis. Importantly, the antitumor effect of 17-DMAG and ferroptosis damage were amplified using photothermal effect of HMPB by accelerating release of ferric and ferrous ions, and reducing HSP90 expression in cells, which induced powerful antitumor effect in vitro and in vivo. This multi-hit therapeutic nanosystem helps provide a novel perspective for solving the predicament of cancer treatment, as well as a promising strategy for design of a novel cancer treatment nanoplatform.

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The tumor specific multi-hit therapeutic nanosystem was constructed.

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The nanosystem exerts anti-tumor effect includes photothermal effect, cell signaling pathway regulation and ferroptosis.

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The synergistic 17-DMAG-HMPB@sPP@HA nanosystem offers a promising strategy for effective tumor therapies.

Role of pyroptosis in cancer and its therapeutic regulation

Pyroptosis is mainly considered a gasdermin-regulated cell death mechanism characterized by cellular lysis and the release of several pro-inflammatory factors. Nowadays, pyroptosis has notably been gained extensive attention from clinicians and researchers. However, current studies report that downregulation of pyroptosis-mediated cell death plays a significant role in developing multiple cancers. Increasing studies also suggest that pyroptosis can impact all stages of carcinogenesis. Inducing pyroptotic cellular death could be a promising therapeutic option for managing and regulating multiple cancers in the near future. Our current review highlights the molecular and morphological features of pyroptosis and its potential roles in various cancers. In addition, we have also highlighted the biological characteristics and significances of GSDMD and GSDME and their critical functions in cancer progression, management and regulation.

Advances in deubiquitinating enzymes in lung adenocarcinoma

The process of ubiquitination and deubiquitination is widely present in the human body's protein reactions and plays versatile roles in multiple diseases. Deubiquitinating enzymes (DUBs) are significant regulators of this process, which cleave the ubiquitin (Ub) moiety from various substrates and maintain protein stability. Lung adenocarcinoma (LUAD) is the most common type of non-small cell lung cancer (NSCLC) and remains refractory to treatment. To elucidate the mechanism of LUAD and advance new therapeutic targets, we review the latest research progress on DUBs in LUAD. We summarize the biological capabilities of these DUBs and further highlight those DUBs that may serve as anticancer target candidates for precision treatment. We also discuss deubiquitinase inhibitors, which are expected to play a role in targeted LUAD therapy.

Cyclin A2 localises in the cytoplasm at the S/G2 transition to activate PLK1

Cyclin A2 is a key regulator of the cell cycle, implicated both in DNA replication and mitotic entry. Cyclin A2 participates in feedback loops that activate mitotic kinases in G2 phase, but why active Cyclin A2-CDK2 during the S phase does not trigger mitotic kinase activation remains unclear. Here, we describe a change in localisation of Cyclin A2 from being only nuclear to both nuclear and cytoplasmic at the S/G2 border. We find that Cyclin A2-CDK2 can activate the mitotic kinase PLK1 through phosphorylation of Bora, and that only cytoplasmic Cyclin A2 interacts with Bora and PLK1. Expression of predominately cytoplasmic Cyclin A2 or phospho-mimicking PLK1 T210D can partially rescue a G2 arrest caused by Cyclin A2 depletion. Cytoplasmic presence of Cyclin A2 is restricted by p21, in particular after DNA damage. Cyclin A2 chromatin association during DNA replication and additional mechanisms contribute to Cyclin A2 localisation change in the G2 phase. We find no evidence that such mechanisms involve G2 feedback loops and suggest that cytoplasmic appearance of Cyclin A2 at the S/G2 transition functions as a trigger for mitotic kinase activation.

Sulforaphane induces S-phase arrest and apoptosis via p53-dependent manner in gastric cancer cells

Sulforaphane (SFN) extracted from broccoli sprout has previously been investigated for its potential properties in cancers, however, the underlying mechanisms of the anticancer activity of SFN remain not fully understood. In the present study, we investigate the effects of SFN on cell proliferation, cell cycle, cell apoptosis, and also the expression of several cell cycle and apoptosis-related genes by MTT assay, flow cytometry and western blot analysis in gastric cancer (GC) cells. The results showed that SFN could impair the colony-forming ability in BGC-823 and MGC-803 cell lines compared with the control. In addition, SFN significantly suppressed cell proliferation by arresting the cell cycle at the S phase and enhancing cell apoptosis in GC cells in a dose-dependent manner. Western blot results showed that SFN treatment significantly increased the expression levels of p53, p21 and decreased CDK2 expression, which directly regulated the S phase transition. The Bax and cleaved-caspase-3 genes involved in apoptosis executive functions were significantly increased in a dose-dependent manner in BGC-823 and MGC-803 cells. These results suggested that SFN-induced S phase cell cycle arrest and apoptosis through p53-dependent manner in GC cells, which suggested that SFN has a potential therapeutic application in the treatment and prevention of GC.

IGFBP6 regulates vascular smooth muscle cell proliferation and morphology via cyclin E-CDK2

Despite the high prevalence of varicose veins, the underlying pathogenesis of this disease remains unclear. The present study aims to explore the role of insulin-like growth factor binding protein 6 (IGFBP6) in vascular smooth muscle cells (VSMCs). Using a protein array approach, we identified several differentially expressed proteins between varicose great saphenous veins and normal great saphenous veins. Bioinformatic analysis showed that IGFBP6 was closely related to cell proliferation. Further validation confirmed that IGFBP6 was one of the most highly expressed proteins in varicose vein tissue. Knocking down IGFBP6 in VSMCs significantly attenuated cell proliferation and induced the S phase arrest during the cell cycle. Further experiments demonstrated that IGFBP6 knockdown increased cyclin E ubiquitination, which reduced expression of cyclin E and phosphorylation of CDK2. Furthermore, IGFBP6 knockdown arrested centrosome replication, which subsequently influenced VSMC morphology. Ultimately, IGFBP6 was validated to be involved in VSMC proliferation in varicose vein tissues. The present study reveals that IGFBP6 is closely correlated with VSMC biological function and provides unprecedented insights into the underlying pathogenesis of varicose veins.

Comparative analysis of transcriptomes revealed the molecular mechanism of development of Tricholoma matsutake at different stages of fruiting bodies

The purpose of the study is to investigate the molecular mechanisms of development of Tricholoma matsutake fruiting body at the primordial stage (TM-1), the intermediate stage (TM-2) and the mature stage (TM-3) using RNA-Seq sequencing technology. The analysis of gene expression level revealed that the Spn2 and Eef1a1 gene were the key genes in the primordial stage of T. matsutake by regulating cytokinesis, protein synthesis, and cell growth. And the Ubc, Atp6, Cytb, and Pth2 gene were the key genes in the mature stage of T. matsutake by regulating energy metabolism and protein synthesis. Differential expression genes (DEGs) analysis results showed that Cdc28, Rad53, Dun1, Pho85 and Pho81 were the key DEGs regulating cell cycle genes of T. matsutake from primordial stage to intermediate stage. And APC, Cyr1, Cdc45, Spo11 and Rec8 genes were the key DEGs for the meiosis and sporogenesis of T. matsutake from the intermediate stage to the mature stage.

MeCP2 facilitates breast cancer growth via promoting ubiquitination-mediated P53 degradation by inhibiting RPL5/RPL11 transcription

Methyl-CpG-binding protein 2 (MeCP2) facilitates the carcinogenesis and progression of several types of cancer. However, its role in breast cancer and the relevant molecular mechanism remain largely unclear. In this study, analysis of the Cancer Genome Atlas (TCGA) data that MeCP2 expression was significantly upregulated in breast cancer tissues, and high MeCP2 expression was correlated with poor overall survival. Knockdown of MeCP2 inhibited breast cancer cell proliferation and G1–S cell cycle transition and migration as well as induced cell apoptosis in vitro. Moreover, MeCP2 knockdown suppressed cancer cell growth in vivo. Investigation of the molecular mechanism showed that MeCP2 repressed RPL11 and RPL5 transcription by binding to their promoter regions. TCGA data revealed significantly lower RPL11 and RPL5 expression in breast cancer tissues; additionally, overexpression of RPL11/RPL5 significantly suppressed breast cancer cell proliferation and G1–S cell cycle transition and induced apoptosis in vitro. Furthermore, RPL11 and RPL5 suppressed ubiquitination-mediated P53 degradation through direct binding to MDM2. This study demonstrates that MeCP2 promotes breast cancer cell proliferation and inhibits apoptosis through suppressing RPL11 and RPL5 transcription by binding to their promoter regions.

Gefitinib sensitization of cisplatin-resistant wild-type EGFR non-small cell lung cancer cells

Purpose

The usual first-line strategy of wild-type EGFR (wtEGFR) non-small cell lung cancer (NSCLC) remains cisplatin-based chemotherapy. However, cisplatin often loses effectiveness because most tumors acquire drug resistance over time. As EGFR is the most important pro-survival/proliferation signal receptor in NSCLC cells, we aimed at investigating whether cisplatin resistance is related to EGFR activation and further evaluating the combined effects of cisplatin/gefitinib (EGFR-tyrosine kinase inhibitor, EGFR-TKI) on cisplatin-resistant wtEGFR NSCLC cells.

Materials and methods

EGFR activation was analysed in parental and cisplatin-resistant wtEGFR NSCLC cell lines (H358 and H358^R, A549 and A549^R). Cellular proliferation and apoptosis of H358^R/A549^R cells treated with cisplatin or gefitinib, alone or in combination were investigated, and the related effector protein was detected by western blot analysis. Anti-tumor effect of two drugs combined was evaluated in animal models of H358^R xenografts in vivo.

Results

EGFR was significantly phosphorylated in cisplatin-resistant wtEGFR NSCLC cells H358^R and A549^R than their parental cells. In H358^R and A549^R cells, anti-proliferative ability of gefitinib was further improved, and gefitinib combined with cisplatin enhanced inhibition of cellular survive/proliferation, and promotion of apoptosis in vitro. The combined effects were also associated with the inhibition of EGFR downstream effector proteins. Similarly, in vivo, gefitinib and cisplatin in combination significantly inhibited tumor growth of H358^R xenografts.

Conclusion

Abnormal activation of EGFR may induce wtEGFR NSCLC cell resistance to cisplatin. The combined effects of cisplatin/gefitinib suggest that gefitinib, as a combination therapy for patients with cisplatin-resistant wtEGFR NSCLC should be considered.

SNRPB promotes cervical cancer progression through repressing p53 expression

Cervical cancer is still a leading cause of tumor death in women across the world. Small nuclear ribonucleoprotein polypeptides B and B1 (SNRPB) gene encodes the components of the core spliceosomal machinery, and regulates the development of several types of cancers. However, its function in cervical cancer progression remains unclear. In the study, we found that SNRPB was highly expressed in human cervical cancer tissues and in cervical cancer cell lines. Meanwhile, SNRPB knockdown using shRNA in cervical cancer cells markedly reduced the cell proliferation, migration and invasion. Furthermore, the increased percentage of cells in G2/M phase and apoptotic cell death was detected in cervical cancer cells with SNRPB knockdown, suggesting that SNRPB might contribute to cervical cancer growth. Moreover, we found that SNRPB could directly interact with p53, and the interaction showed an essential role in modulating cervical cancer cell proliferation, migration, invasion and apoptosis. In xenograft model, the knockdown of SNRPB exerted effectively anti-cervical cancer ability characterized by the reduced tumor volume and weight, and a remarkable reduction in KI-67 expression. Improved expression of p53 validated the in vitro findings. Therefore, SNRPB might be a potent therapeutic target in cervical cancer through interacting with p53.

Posttranscriptional control of the replication stress response via TTP-mediated Claspin mRNA stabilization

ATR and CHK1 play key roles in the protection and recovery of the stalled replication forks. Claspin, an adaptor for CHK1 activation, is essential for DNA damage signaling and efficient replication fork progression. Here, we show that tristetraprolin (TTP), an mRNA-binding protein, can modulate the replication stress response via stabilization of Claspin mRNA. TTP depletion compromised specifically in the phosphorylation of CHK1, but not p53 or H2AX among other ATR substrates, and produced CHK1-defective replication phenotypes including accumulation of stalled replication forks. Importantly, the expression of siRNA-resistant TTP in TTP-deficient cells restored CHK1 phosphorylation and reduced the number of stalled replication forks as close to the control cells. Besides, we found that TTP was required for efficient replication fork progression even in the absence of exogenous DNA damage in a Claspin-dependent manner. Mechanistically, TTP was able to bind to the 3'-untranslated region of Claspin mRNA to increase the stability of Claspin mRNA which eventually contributed to the subsequent ATR-CHK1 activation upon DNA damage. Taken together, our results revealed an intimate link between TTP-dependent Claspin mRNA stability and ATR-CHK1-dependent replication fork stability to maintain replication fork integrity and chromosomal stability.

Pyroptosis: A new frontier in cancer

Pyroptosis is an inflammatory form of cell death triggered by certain inflammasomes, leading to the cleavage of gasdermin D (GSDMD) and activation of inactive cytokines like IL-18 and IL-1β. Pyroptosis has been reported to be closely associated to some diseases like atherosclerosis and diabetic nephropathy. Recently, some studies found that pyroptosis can influence the proliferation, invasion and metastasis of tumor, which regulated by some non-coding RNAs and other molecules. Hence, we provided an overview of morphological and molecular characteristics of pyroptosis. We also focus on mechanism of regulating pyroptosis in tumor cells as well as the potential roles of pyroptosis in cancer to explore potential diagnostic markers in cancers contributing to the prevention and treatment in cancers.

Supercritical CO2 fluid extraction of croton crassifolius Geisel root: Chemical composition and anti-proliferative, autophagic, apoptosis-inducing, and related molecular effects on A549 tumour cells

BACKGROUND

The use of plant essential oils as pharmaceuticals is a fast-growing market especially in China. Throughout the 20th century, a rapid increase took place in the use of many essential oil-derived products in the medicinal industry as nutraceuticals, medicinal supplements, and pharmaceuticals.

PURPOSE

The objective of this study was to explore the chemical composition of Croton crassifolius essential oil as well as its potential anti-tumour properties and related anti-proliferative, autophagic, and apoptosis-inducing effects.

METHODS

Supercritical CO₂ fluid extraction technology was used to extract CCEO and the chemical constituents of the essential oil were identified by comparing the retention indices and mass spectra data taken from the NIST library with those calculated based on the C7-C40 n-alkanes standard. The cytotoxic activity and anti-proliferative effects of CCEO were evaluated against five cancer cell lines and one normal human cell line via CCK-8 assays. In addition, flow cytometry was used to detect cell cycle arrest. The efficacy of CCEO treatments in controlling cancer cell proliferation was assessed by cell cycle analysis, clonal formation assays, RT-qPCR, and western blot analysis. Autophagic and apoptosis-inducing effects of oils and the associated molecular mechanisms were assessed by flow cytometry, cell staining, reactive oxygen species assays, RT-qPCR, and western blot analysis.

CONCLUSION

Forty compounds representing 92.90% of the total oil were identified in CCEO. The results showed that CCEO exerted a measurable selectivity for cancer cell lines, especially for A549 with the lowest IC₅₀ value of 25.00 ± 1.62 μg/mL. Assessment of the anti-proliferative effects of CCEO on A549 cells showed that the oil inhibited cell proliferation and colony formation in a dose- and time-dependent manner. Investigation of the molecular mechanisms of cell cycle regulation confirmed that the oil arrested A549 cells in G2/M phase by decreasing the expression of cyclin B1-CDK1 and cyclin A-CDK1 and increasing the expression of cyclin-dependent kinase inhibitor (CKI) P21 at both the transcriptional and translational levels. Autophagy staining assays and western blot analysis revealed that CCEO promoted the formation of autophagic vacuoles in A549 cells and increased the expression of autophagy-related proteins beclin-1 and LC3-II in a dose-dependent manner. A series of apoptosis analyses indicated that CCEO induces apoptosis through a mitochondria-mediated intrinsic pathway. This study revealed that CCEO is a promising candidate for development into an anti-tumour drug of the future.

Mechanism of Juglone-Induced Cell Cycle Arrest and Apoptosis in Ishikawa Human Endometrial Cancer Cells

The molecular mechanism of Juglone-induced cell cycle arrest and apoptosis in human endometrial cancer cells was investigated. Juglone was purified from the green husk of Carya cathayensis Sarg and identified by HPLC, LC-MS/MS, and NMR. At an IC₅₀ of 20.81 μM, juglone significantly inhibited Ishikawa cell proliferation, as shown by S phase arrest mediated by inactivation of cyclin A protein ( p < 0.05). The ROS levels increased significantly after exposure to juglone, which paralleled increases in the mRNA and protein expression of p21 and decreases in the levels of CDK2, cdc25A, CHK1, and cyclin A. The expression of Bcl-2 and Bcl-xL was significantly down-regulated, whereas the expression of Bax, Bad and cyto c was up-regulated, and we later confirmed the involvement of the mitochondrial pathway in juglone-induced apoptosis. Our in vitro results stated that juglone can be studied further as an effective natural anticancer agent.

The oncogenic potential of PRR11 gene in Tongue Squamous Cell Carcinoma cells

Background: We previously demonstrated that Proline rich 11 (PRR11) gene is associated with the development and progression of tongue squamous cell carcinoma (TSCC), but the underlying mechanism is unknown. This study aimed to investigate the molecular mechanism underlying oncogenic potential of PRR11 in TSCC cells. Methods: Overexpression and knockdown of PRR11 were performed by plasmid transfection into SCC15 and HSC3 human TSCC cells. Expressions of mRNA and protein were assessed by qRT-PCR and Western blot, respectively. Cell proliferation and invasion were determined by CCK-8 and Transwell assay, respectively. In vivo tumor growth and cell cycle were determined by a nude mice model of subcutaneous tumorigenesis and flow cytometry, respectively. Results: Overexpression of PRR11 significantly enhanced TSCC cells proliferation and the invasive ability of TSCC cells, whereas PRR11 knockdown in TSCC cells exhibited a reverse trend. In addition, the in vivo subcutaneous tumorigenicity assay showed that PRR11 knockdown significantly reduced tumor size and the Ki67 (a proliferation marker)expression in the tumor tissue. Flow cytometry analysis revealed that PRR11 overexpression significantly decreased the proportion of cells in S phase, whereas PRR11 knockdown in TSCC cells exhibited a reverse trend. Furthermore, PRR11 overexpression simultaneously down-regulated two cyclin-dependent kinase inhibitors (CKIs), p21 and p27 and up-regulated CDK2 and Cyclin A2 in TSCC cells. PRR11 knockdown again exhibited reverse trends of expressions of the above proteins.Conclusion: These results suggested that PRR11 promoted cell proliferation by regulating the expressions of p21, p27, CDK2 and Cyclin A to facilitate S/G phase transition in TSCC cells.

Control of DNA Replication Initiation by Ubiquitin

Eukaryotic cells divide by accomplishing a program of events in which the replication of the genome is a fundamental part. To ensure all cells have an accurate copy of the genome, DNA replication occurs only once per cell cycle and is controlled by numerous pathways. A key step in this process is the initiation of DNA replication in which certain regions of DNA are marked as competent to replicate. Moreover, initiation of DNA replication needs to be coordinated with other cell cycle processes. At the molecular level, initiation of DNA replication relies, among other mechanisms, upon post-translational modifications, including the conjugation and hydrolysis of ubiquitin. An example is the precise control of the levels of the DNA replication initiation protein Cdt1 and its inhibitor Geminin by ubiquitin-mediated proteasomal degradation. This control ensures that DNA replication occurs with the right timing during the cell cycle, thereby avoiding re-replication events. Here, we review the events that involve ubiquitin signalling during DNA replication initiation, and how they are linked to human disease.

Targeting inhibitors of apoptosis proteins suppresses medulloblastoma cell proliferation via G2/M phase arrest and attenuated neddylation of p21

Medulloblastoma (MB) is the most common type of malignant childhood brain tumor. We previously showed that inhibitors of apoptosis proteins (IAP) small‐molecule inhibitors (LCL161 or LBW242) combined with chemotherapy have synergistic antiproliferative effects on MB cells. The synergistic antitumor effects of combination treatments happen through induction of autophagy and caspase‐3/7‐activated apoptosis. Here, we investigated the effects of IAP inhibitors or silencing IAP on cell cycle regulation. We discovered that treatment with IAP inhibitors or their combination with conventional chemotherapy (vincristine or cisplatin), as well as RNAi knockdown of cIAP1/2 or XIAP arrested MB cells in the G2/M phase through downregulation of cyclin B1‐CDK1 and cyclin A‐CDK1/2. Among these three IAPs, only silencing cIAP1 expression enhanced p21 dependent‐G2/M phase accumulation. IAP inhibitors reduced cIAP1 expression and increased p21 expression in time course experiments. Furthermore, cIAP1 can govern p21 proteasomal degradation via neddylation in lieu of ubiquitination. Inhibition of IAPs significantly abrogated cIAP1‐mediated p21 degradation. We also observed an inverse correlation between nuclear cIAP1 and nuclear p21 expressions in MB tumor tissues. These findings provide new mechanistic evidence of the influence of IAP inhibitors on MB cell proliferation through disruption of the cell cycle.

The In Vitro Anti-Tumor Activity of Phycocyanin against Non-Small Cell Lung Cancer Cells

Phycocyanin, a type of functional food colorant, is shown to have a potent anti-cancer property. Non-small cell lung cancer (NSCLC) is one of the most aggressive form of cancers with few effective therapeutic options. Previous studies have demonstrated that phycocyanin exerts a growth inhibitory effect on NSCLC A549 cells. However, its biological function and underlying regulatory mechanism on other cells still remain unknown. Here, we investigated the in vitro function of phycocyanin on three typical NSCLC cell lines, NCI-H1299, NCI-H460, and LTEP-A2, for the first time. The results showed that phycocyanin could significantly induce apoptosis, cell cycle arrest, as well as suppress cell migration, proliferation, and the colony formation ability of NSCLC cells through regulating multiple key genes. Strikingly, phycocyanin was discovered to affect the cell phenotype through regulating the NF-κB signaling of NSCLC cells. Our findings demonstrated the anti-neoplastic function of phycocyanin and provided valuable information for the regulation of phycocyanin in NSCLC cells.

Dexamethasone-induced production of reactive oxygen species promotes apoptosis via endoplasmic reticulum stress and autophagy in MC3T3-E1 cells

Apoptosis of osteoblasts, triggered by prolonged or excessive use of glucocorticoids (GCs), has been identified as a dominant contributor to the development of osteoporosis and osteonecrosis. However, the molecular mechanisms underlying GC‑induced apoptosis are multifaceted and remain to be fully elucidated. The present study aimed to explore the correlation between dexamethasone (DEX)‑induced reactive oxygen species (ROS), autophagy and apoptosis in MC3T3‑E1 osteoblast‑like cells. Cell viability was assessed using a Cell Counting Kit‑8 assay, and flow cytometry was performed to assess cellular apoptosis, cell cycle and ROS production. Immunofluorescence and western blot analysis were respectively used to detect autophagic vacuoles and the expression of proteins, including cyclin D kinase (CDK)2, poly[ADP ribose] polymerase, caspase‑3, activating transcription factor (ATF)4, CCAAT/enhancer‑binding protein homologous protein (CHOP), Beclin1, microtubule‑associated proteins 1A/1B light chain (LC)3B and P62. It was revealed that DEX not only reduced cell viability, but also promoted apoptosis via the activation of endoplasmic reticulum (ER) stress. In addition, DEX induced cell cycle arrest at G0/G1 phase via inhibition of the expression of CDK2, and the production of ROS was activated. Of note, the DEX‑mediated changes in viability and apoptosis were attenuated in MC3T3‑E1 cells after treatment with 3‑methyladenine, which is an autophagy inhibitor. Treatment with the antioxidant N‑acetylcysteine abolished the effect of DEX on the proliferation, apoptosis, ER stress and autophagy of MC3T3‑E1 cells. In conclusion, the present results indicated that DEX promoted the production of ROS, which enhanced apoptosis through activation of autophagy and ER stress in MC3T3-E1 cells.

A Pyrazolo[3,4-d]pyrimidine compound inhibits Fyn phosphorylation and induces apoptosis in natural killer cell leukemia

Natural killer (NK) cell neoplasms are characterized by clonal proliferation of cytotoxic NK cells. Since there is no standard treatment to date, new therapeutic options are needed, especially for NK aggressive tumors. Fyn tyrosine kinase has a key role in different biological processes, such as cell growth and differentiation, being also involved in the pathogenesis of hematologic malignancies. Our previous studies led us to identify 4c pyrazolo[3,4-d]pyrimidine compound capable of inhibiting Fyn activation and inducing apoptosis in different cancer cell lines. Here we investigated the presence of Fyn and the effect of its inhibitor in NK malignant cells. Firstly, we showed Fyn over-expression in NK leukemic cells compared to peripheral blood mononuclear cells from healthy donors. Subsequently, we demonstrated that 4c treatment reduced cell viability, induced caspase 3-mediate apoptosis and cell cycle arrest in NK cells. Moreover, by inhibiting Fyn phosphorylation, 4c compound reduced Akt and P70 S6 kinase activation and changed the expression of genes involved in cell death and survival in NK cells. Our study demonstrated that Fyn is involved in the pathogenesis of NK leukemia and that it could represent a potential target for this neoplasm. Moreover, we proved that Fyn inhibitor pyrazolo[3,4-d]pyrimidine compound, could be a started point to develop new therapeutic agents.

Downregulation of gasdermin D promotes gastric cancer proliferation by regulating cell cycle-related proteins

OBJECTIVE

To explore the relationship between gasdermin D (GSDMD) and gastric cancer (GC) cell proliferation, and to determine whether the downregulated expression of GSDMD contributed to the tumorigenesis and proliferation of GC cells.

METHODS

GSDMD expressions in GC tissues and matched adjacent non-cancerous tissues were assessed by quantitative real-time polymerase chain reaction, Western blot and immunohistochemistry. The effect of GSDMD on cell proliferation in vitro was assessed by the colony formation assay and cell viability assays. In vivo, xenografted tumors in nude mice were evaluated. The cell cycle was analyzed by flow cytometry. In addition, the alterations of several cell cycle-related and cell signaling pathway proteins were analyzed by Western blot.

RESULTS

GSDMD expression was decreased in GC, and the decreased expression of GSDMD could markedly promote the proliferation of tumors in vivo and in vitro. The downregulation of GSDMD accelerated S/G₂ cell transition by activating extracellular signal regulated kinase, signal transducer and activator of transcription 3 and phosphatidylinositol 3 kinase/protein kinase B signaling pathways and regulating cell cycle-related proteins in GC.

CONCLUSION

GSDMD may protect against cell proliferation of GC, and it may be used as a diagnostic and treatment strategy for GC.

Analysis of DNA methylation in chondrocytes in rats with knee osteoarthritis

BACKGROUND

Knee osteoarthritis (KOA) is a degenerative knee disease commonly found in the ageing population. DNA methylation works with histone acetylation to participate in aging. Alterations of DNA methylation may involve the joint chondrocyte degeneration in KOA. The aim of this study is to detect DNA methylation changes in chondrocytes of rats with KOA.

METHODS

The rat KOA model was established with the Hulth method (n = 10), while rats receiving sham operation served as the control (n = 10). At 16 weeks after modeling, the knee joint tissue was collected from half of the rats in each group for Micro-CT scanning, Haematoxylin& Eosin (HE) staining, ABH/OG staining, immunohistochemistry for Bax, Bcl-2 and Fas, and TUNNEL staining. Meanwhile, the articular cartilage was collected from the other half to detect promoter methylation in target genes with the MethylTarget approach.

RESULTS

Micro-CT scanning, HE staining, ABH/OG staining, immunohistochemistry, and TUNNEL staining all showed more severe cartilage injury in the KOA group than in the control group, indicating successful establishment of KOA model. The methylation rate in the KOA group was significantly decreased for C/ebpα-2 (within a CpG island -452 bp to the initiation codon on chromosome 1 91,363,511), Cdk2 (within a CpG island -55 bp to the initiation codon on chromosome 7 3,132,362), Bak1 (within a CpG island 6452 bp to the initiation codon on chromosome 20 5,622,277), and Fas (within a CpG island on the entire chromosome 1 gene), compared with the sham group (P = 0.005, 0.008, 0.022 and 0.027, respectively).

CONCLUSION

The chondrocyte apoptosis and significantly reduced methylation levels of C/ebpα-2, Cdk2, Bak1, and Fas may participate in the pathogenesis of KOA. However, the exact mechanisms remain to be determined.

Anaphase-Promoting Complex Adaptor FZR1/CDH1 Blocks BRAF Signaling Both by Targeting BRAF for Proteolytic Degradation and by Disrupting BRAF Dimerization

<b/> Blocking dimerization and stimulating protein degradation are two mechanisms known to inhibit BRAF activity. The study reported by Wan and colleagues identifies BRAF as a substrate of the APC/C^FZR1-ubiqutin-proteasome system. The interaction between FZR1 and BRAF also induces a conformational change that disrupts BRAF dimerization. These findings identify a dynamic interplay between FZR1 and BRAF with strong implications for cell-fate determination and the tumor suppressor role of FZR1. Cancer Discov; 7(4); 356-8. ©2017 AACRSee related article by Wan et al., p. 424.

The T-Box factor TBX3 is important in S-phase and is regulated by c-Myc and cyclin A-CDK2

The transcription factor, TBX3, is critical for the formation of, among other structures, the heart, limbs and mammary glands and haploinsufficiency of the human TBX3 gene result in ulnar-mammary syndrome which is characterized by hypoplasia of these structures. On the other hand, the overexpression of TBX3 is a feature of a wide range of cancers and it has been implicated in several aspects of the oncogenic process. This includes its ability to function as an immortalizing gene and to promote proliferation through actively repressing negative cell cycle regulators. Together this suggests that TBX3 levels may need to be tightly regulated during the cell cycle. Here we demonstrate that this is indeed the case and that TBX3 mRNA and protein levels peak at S-phase and that the TBX3 protein is predominantly localized to the nucleus of S-phase cells. The increased levels of TBX3 in S-phase are shown to occur transcriptionally through activation by c-Myc at E-box motifs located at -1210 and -701 bps and post-translationally by cyclin A-CDK2 phosphorylation. Importantly, when TBX3 is depleted by shRNA the cells accumulate in S-phase. These results suggest that TBX3 is required for cells to transit through S-phase and that this function may be linked to its role as a pro-proliferative factor.

Phosphorylation of CDC25A on SER283 in late S/G2 by CDK/cyclin complexes accelerates mitotic entry

The Cdc25A phosphatase is an essential activator of CDK-cyclin complexes at all steps of the eukaryotic cell cycle. The activity of Cdc25A is itself regulated in part by positive and negative feedback regulatory loops performed by its CDK-cyclin substrates that occur in G1 as well as during the G1/S and G2/M transitions. However, the regulation of Cdc25A during G2 phase progression before mitotic entry has not been intensively characterized. Here, we identify by mass spectrometry analysis a new phosphorylation event of Cdc25A on Serine283. Phospho-specific antibodies revealed that the phosphorylation of this residue appears in late S/G2 phase of an unperturbed cell cycle and is performed by CDK-cyclin complexes. Overexpression studies of wild-type and non-phosphorylatable mutant forms of Cdc25A indicated that Ser283 phosphorylation increases the G2/M-promoting activity of the phosphatase without impacting its stability or subcellular localization. Our results therefore identify a new positive regulatory loop between Cdc25A and its CDK-cyclin substrates which contributes to accelerate entry into mitosis through the regulation of Cdc25A activity in G2.

RY-2f, an isoflavone analog, overcomes cisplatin resistance to inhibit ovarian tumorigenesis via targeting the PI3K/AKT/mTOR signaling pathway

Ovarian cancer remains the leading cause of death in gynecologic malignancies partially because of resistance to chemotherapy. In the present study, we show that RY-2f, a chemically synthesized isoflavone analog, inhibited ovarian cancer cell proliferation, blocked cell cycle in G2/M phase and induced cellular apoptosis through up-regulation of p21, cyclin B1, Bax, Bad and cleaved-PARP, and suppression of cyclin A, CDK2 and Bcl-2. We also show that RY-2f could increase the chemotherapeutic efficacy of cisplatin as tested by cell proliferation and colony formation assays, indicating a synergistic effect of RY-2f and cisplatin. Mechanistic study revealed that RY-2f exerted the anti-tumor activities mainly through suppression of the PI3K/AKT/mTOR signaling. Finally, in vivo studies showed that RY-2f blocked the A2780-induced xenograft tumor growth without detectable toxicity in the animals at the therapeutic doses, and whereas RY-2f re-sensitized the cisplatin resistant cell line A2780/CDDP induced xenograft tumor to cisplatin treatment. Thus, RY-2f may be developed as a potential therapeutic agent to treat ovarian cancer.