Icariin induces apoptosis by suppressing autophagy in tamoxifen-resistant breast cancer cell line MCF-7/TAM

Epimedium Linn: A Comprehensive Review of Phytochemistry, Pharmacology, Clinical Applications and Quality Control

Epimedium genus is a traditional Chinese medicine, which has functions of tonifying kidney and yang, strengthening tendons and bones, dispelling wind and emoving dampness. It is mainly used for the treatment of impotence and spermatorrhea, osteoporosis, Parkinson's, Alzheimer's, and cardiovascular diseases. The aim of this review is to provide a systematic summary of the phytochemistry, pharmacology, and clinical applications of the Epimedium Linn. In this paper, the relevant literature on Epimedium Linn. was collected from 1987 to the present day, and more than 274 chemical constituents, including flavonoids, phenylpropanoids, lignans, phenanthrenes, and others, were isolated from this genus. Modern pharmacological studies have shown that Epimedium Linn. has osteoprotective, neuroprotective, cardiovascular protective, and immune enhancing pharmacological effects. In addition, Epimedium Linn. has been commonly used to treat osteoporosis, erectile dysfunction, hypertension and cardiovascular disease. In this paper, the distribution of resources, chemical compositions, pharmacological effects, clinical applications and quality control of Epimedium Linn. are progressed to provide a reference for further research and development of the resources of this genus.

Natural autophagy modulators in non-communicable diseases: from autophagy mechanisms to therapeutic potential

Non-communicable diseases (NCDs) are defined as a kind of diseases closely related to bad behaviors and lifestyles, e.g., cardiovascular diseases, cancer, and diabetes. Driven by population growth and aging, NCDs have become the biggest disease burden in the world, and it is urgent to prevent and control these chronic diseases. Autophagy is an evolutionarily conserved process that degrade cellular senescent or malfunctioning organelles in lysosomes. Mounting evidence has demonstrated a major role of autophagy in the pathogenesis of cardiovascular diseases, cancer, and other major human diseases, suggesting that autophagy could be a candidate therapeutic target for NCDs. Natural products/phytochemicals are important resources for drugs against a wide variety of diseases. Recently, compounds from natural plants, such as resveratrol, curcumin, and ursolic acid, have been recognized as promising autophagy modulators. In this review, we address recent advances and the current status of the development of natural autophagy modulators in NCDs and provide an update of the latest in vitro and in vivo experiments that pave the way to clinical studies. Specifically, we focus on the relationship between natural autophagy modulators and NCDs, with an intent to identify natural autophagy modulators with therapeutic potential.

Cancer-Related Therapeutic Potential of Epimedium and Its Extracts

Epimedium is a Chinese herb known as "yin and yang fire," first mentioned in the Compendium of Materia Medica. Many of the proprietary Chinese medicines used in clinical practice contain Epimedium as an ingredient, and its main active constituents include icariin, icaritin, and icariside II, among others. In addition to its traditional use in treating fatigue and sexual problems, modern research has confirmed that the main bioactive compounds in Epimedium have pharmacological effects such as antidepressant, antibacterial, antiviral, antioxidant, and anti-inflammatory properties, as well as inhibiting bone destruction, promoting bone growth, improving immune regulation and protecting the cardio-cerebral vascular system. With the continuous development of extraction and purification techniques, the development and use of bioactive compounds in Epimedium have significantly progressed, and the anticancer effect has received widespread attention. Since natural herbs have few side effects on the human body and do not easily develop drug resistance, they have long been the direction of research in cancer treatment. This review summarizes the latest research on the anticancer effects of Epimedium and its extracts, describes the bioactive compounds, pharmacological efficacy, and antitumor mechanism of Epimedium, and gives a new view on the administration and development of Epimedium.

Abrogating PDK4 activates autophagy-dependent ferroptosis in breast cancer via ASK1/JNK pathway

BACKGROUND

Targeting ferroptosis mediated by autophagy presents a novel therapeutic approach to breast cancer, a mortal neoplasm on the global scale. Pyruvate dehydrogenase kinase isozyme 4 (PDK4) has been denoted as a determinant of breast cancer metabolism. The target of this study was to untangle the functional mechanism of PDK4 in ferroptosis dependent on autophagy in breast cancer.

METHODS

RT-qPCR and western blotting examined PDK4 mRNA and protein levels in breast cancer cells. Immunofluorescence staining appraised light chain 3 (LC3) expression. Fe (2 +) assay estimated total iron level. Relevant assay kits and C11-BODIPY (591/581) staining evaluated lipid peroxidation level. DCFH-DA staining assayed intracellular reactive oxygen species (ROS) content. Western blotting analyzed the protein levels of autophagy, ferroptosis and apoptosis-signal-regulating kinase 1 (ASK1)/c-Jun N-terminal kinase (JNK) pathway-associated proteins.

RESULTS

PDK4 was highly expressed in breast cancer cells. Knockdown of PDK4 induced the autophagy of breast cancer cells and 3-methyladenine (3-MA), an autophagy inhibitor, countervailed the promoting role of PDK4 interference in ferroptosis in breast cancer cells. Furthermore, PDK4 knockdown activated ASK1/JNK pathway and ASK1 inhibitor (GS-4997) partially abrogated the impacts of PDK4 absence on the autophagy and ferroptosis in breast cancer cells.

CONCLUSION

To sum up, deficiency of PDK4 activated ASK1/JNK pathway to stimulate autophagy-dependent ferroptosis in breast cancer.

Exploiting Nanotechnology for Drug Delivery: Advancing the Anti-Cancer Effects of Autophagy-Modulating Compounds in Traditional Chinese Medicine

Background

Cancer continues to be a prominent issue in the field of medicine, as demonstrated by recent studies emphasizing the significant role of autophagy in the development of cancer. Traditional Chinese Medicine (TCM) provides a variety of anti-tumor agents capable of regulating autophagy. However, the clinical application of autophagy-modulating compounds derived from TCM is impeded by their restricted water solubility and bioavailability. To overcome this challenge, the utilization of nanotechnology has been suggested as a potential solution. Nonetheless, the current body of literature on nanoparticles delivering TCM-derived autophagy-modulating anti-tumor compounds for cancer treatment is limited, lacking comprehensive summaries and detailed descriptions.

Methods

Up to November 2023, a comprehensive research study was conducted to gather relevant data using a variety of databases, including PubMed, ScienceDirect, Springer Link, Web of Science, and CNKI. The keywords utilized in this investigation included "autophagy", "nanoparticles", "traditional Chinese medicine" and "anticancer".

Results

This review provides a comprehensive analysis of the potential of nanotechnology in overcoming delivery challenges and enhancing the anti-cancer properties of autophagy-modulating compounds in TCM. The evaluation is based on a synthesis of different classes of autophagy-modulating compounds in TCM, their mechanisms of action in cancer treatment, and their potential benefits as reported in various scholarly sources. The findings indicate that nanotechnology shows potential in enhancing the availability of autophagy-modulating agents in TCM, thereby opening up a plethora of potential therapeutic avenues.

Conclusion

Nanotechnology has the potential to enhance the anti-tumor efficacy of autophagy-modulating compounds in traditional TCM, through regulation of autophagy.

The therapeutic potential of natural metabolites in targeting endocrine-independent HER-2-negative breast cancer

Breast cancer (BC) is a heterogenous disease, with prognosis and treatment options depending on Estrogen, Progesterone receptor, and Human Epidermal Growth Factor Receptor-2 (HER-2) status. HER-2 negative, endocrine-independent BC presents a significant clinical challenge with limited treatment options. To date, promising strategies like immune checkpoint inhibitors have not yielded breakthroughs in patient prognosis. Despite being considered archaic, agents derived from natural sources, mainly plants, remain backbone of current treatment. In this context, we critically analyze novel naturally-derived drug candidates, elucidate their intricate mechanisms of action, and evaluate their pre-clinical in vitro and in vivo activity in endocrine-independent HER-2 negative BC. Since pre-clinical research success often does not directly correlate with drug approval, we focus on ongoing clinical trials to uncover current trends. Finally, we demonstrate the potential of combining cutting-edge technologies, such as antibody-drug conjugates or nanomedicine, with naturally-derived agents, offering new opportunities that utilize both traditional cytotoxic agents and new metabolites.

Icariin Regulates EMT and Stem Cell-Like Character in Breast Cancer through Modulating lncRNA NEAT1/TGFβ/SMAD2 Signaling Pathway

Metastases and drug resistance are the major risk factors associated with breast cancer (BC), which is the most common type of tumor affecting females. Icariin (ICA) is a traditional Chinese medicine compound that possesses significant anticancer properties. Long non-coding RNAs (lncRNAs) are involved in a wide variety of biological and pathological processes and have been shown to modulate the effectiveness of certain drugs in cancer. The purpose of this study was to examine the potential effect of ICA on epithelial mesenchymal transition (EMT) and stemness articulation in BC cells, as well as the possible relationship between its inhibitory action on EMT and stemness with the NEAT1/transforming growth factor β (TGFβ)/SMAD2 pathway. The effect of ICA on the proliferation (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony assays), EMT (Western blotting, immunofluorescence, and wound healing), and stemness (mammosphere formation assays, Western blotting) of BC cells were examined. According to the findings, ICA suppressed the proliferation, EMT, and stem cell-like in MDA-MB-231 cells, and exerted its inhibitory impact by downregulating the TGFβ/SMAD2 signaling pathway. ICA could significantly downregulate the expression of lncRNA NEAT1, and silencing NEAT1 enhanced the effect of ICA in suppressing EMT and expression of different stem cell markers. In addition, silencing NEAT1 was found to attenuate the TGFβ/SMAD2 signaling pathway, thereby improving the inhibitory impact of ICA on stemness and EMT in BC cells. In conclusion, ICA can potentially inhibit the metastasis of BC via affecting the NEAT1/TGFβ/SMAD2 pathway, which provides a theoretical foundation for understanding the mechanisms involved in potential application of ICA for BC therapy.

Icariin inhibits prostate cancer bone metastasis and destruction via suppressing TAM/CCL5-mediated osteoclastogenesis

BACKGROUND

Bone metastasis occurs in nearly 70% of patients with metastatic prostate cancer (PCa), and represents the leading cause of death in patients with PCa. Emerging evidence has demonstrated the potential activities of icariin in modulating bone metabolism and remodelling the tumor microenvironment (TME). However, whether icariin could inhibit PCa bone metastasis and destruction by modulating the TME as well as the underlying mechanisms remains unclear.

PURPOSE

This study investigated whether icariin could inhibit PCa bone metastasis and destruction by modulating the bone TME as well as the underlying mechanisms.

METHODS

Osteoclasts were induced from mouse bone marrow-derived macrophages (BMMs) or Raw264.7 cells. PCa cells were cultured in the conditional medium (CM) of macrophages in vitro or co-injected with macrophages in vivo to simulate their coexistence in the TME. Multiple molecular biology experiments and the mouse RM1-Luc PCa bone metastasis model were used to explore the inhibitory activity and mechanism of icariin on PCa metastasis and bone destruction.

RESULTS

Icariin treatment significantly suppressed PCa growth, bone metastasis and destruction as well as osteoclastogenesis in vivo. Furthermore, icariin remarkably inhibited osteoclast differentiation, even in the presence of the CM of tumor-associated macrophages (TAMs), while exhibiting no obvious effect on osteoblasts. Moreover, icariin suppressed the M2 phenotype polarization of Raw264.7-derived TAMs and transcriptionally attenuated their CC motif chemokine ligand 5 (CCL5) expression and secretion via inhibiting SPI1. Additionally, CCL5 induced the differentiation and chemotaxis of osteoclast precursor cells by binding with its receptor CCR5. The clinicopathological analysis further verified the positive correlation between the TAM/CCL5/CCR5 axis and osteoclastogenesis within the TME of PCa patients. More importantly, icariin remarkably suppressed PCa metastasis-induced bone destruction in vivo by inhibiting osteoclastogenesis via downregulating the TAM/CCL5 pathway.

CONCLUSION

Altogether, these results not only implicate icariin as a promising candidate immunomodulator for PCa bone metastasis and destruction but also shed novel insight into targeting TAM/CCL5-mediated osteoclastogenesis as a potential treatment strategy for osteolytic bone metastasis. This study helps to advance the understanding of the crosstalk between bone TME and bone homeostasis.

Jatrophone: a cytotoxic macrocylic diterpene targeting PI3K/AKT/NF-κB pathway, inducing apoptosis and autophagy in resistant breast cancer cells

BACKGROUND

Breast cancer is a prevalent malignant tumor that affects women worldwide. The primary challenge in treating breast cancer is combating drug resistance, which contributes to relapse and metastasis. Jatrophone is a unique macrocyclic jatrophane diterpene found in various Jatropha and Euphorbia species. It possesses diverse biological and pharmacological activities, including anticancer activity. However, it is unclear whether jatrophone can overcome drug resistance in breast cancer.

METHODS

This study includes the investigation of the cytotoxicity of jatrophone on doxorubicin-resistant breast cancer cells (MCF-7ADR) and the underlying molecular mechanisms. The effects of jatrophone on cell viability were determined using the sulforhodamine B (SRB) assay, while flow cytometry was used to evaluate cell cycle progression, apoptosis, and autophagy. A scratch assay was conducted to observe cell migration, and western blotting was used to measure downstream protein levels (PI3K, AKT, and NF-κB). Unpaired Student's t-tests were used for comparison between the two groups and the results were analyzed by one-way ANOVA with Tukey- Kremer post hoc test.

RESULTS

It was shown that jatrophone exhibited potent cytotoxic activity on MCF-7ADR cells in a dose-dependent manner, with an IC50 value of 1.8 µM. It also significantly induced cell cycle S and G/M phase arrest. Interestingly, jatrophone induced both early and late apoptotic cell death, as well as autophagic cell death, with negligible necrosis. Furthermore, jatrophone treatment diminished the migration of MCF-7ADR cells. At the molecular level, jatrophone treatment significantly down-regulated the expression levels of PI3K, AKT, and NF-κB. β.

CONCLUSIONS

The results of the study suggest that jatrophone decreases the proliferation of MCF-7/ADR cells at a low micromolar concentration; induces cell cycle arrest; promotes apoptotic, and autophagic cell death; inhibits migration and EMT; and works on resistance by a mechanism involving the inhibition of the PI3K/Akt/ NF-κB pathway. These findings provide evidence of the potential of jatrophone to be a promising lead compound for targeting doxorubicin-resistant breast cancer cells and could be further investigated for its clinical application as a chemotherapy adjuvant.

Towards dual function of autophagy in breast cancer: A potent regulator of tumor progression and therapy response

As a devastating disease, breast cancer has been responsible for decrease in life expectancy of females and its morbidity and mortality are high. Breast cancer is the most common tumor in females and its treatment has been based on employment of surgical resection, chemotherapy and radiotherapy. The changes in biological behavior of breast tumor relies on genomic and epigenetic mutations and depletions as well as dysregulation of molecular mechanisms that autophagy is among them. Autophagy function can be oncogenic in increasing tumorigenesis, and when it has pro-death function, it causes reduction in viability of tumor cells. The carcinogenic function of autophagy in breast tumor is an impediment towards effective therapy of patients, as it can cause drug resistance and radio-resistance. The important hallmarks of breast tumor such as glucose metabolism, proliferation, apoptosis and metastasis can be regulated by autophagy. Oncogenic autophagy can inhibit apoptosis, while it promotes stemness of breast tumor. Moreover, autophagy demonstrates interaction with tumor microenvironment components such as macrophages and its level can be regulated by anti-tumor compounds in breast tumor therapy. The reasons of considering autophagy in breast cancer therapy is its pleiotropic function, dual role (pro-survival and pro-death) and crosstalk with important molecular mechanisms such as apoptosis. Moreover, current review provides a pre-clinical and clinical evaluation of autophagy in breast tumor.

Therapeutic Properties of Flavonoids in Treatment of Cancer through Autophagic Modulation: A Systematic Review

Cancers have high morbidity and mortality rates worldwide. Current anticancer therapies have demonstrated specific signaling pathways as a target in the involvement of carcinogenesis. Autophagy is a quality control system for proteins and plays a fundamental role in cancer carcinogenesis, exerting an anticarcinogenic role in normal cells and can inhibit the transformation of malignant cells. Therefore, drugs aimed at autophagy can function as antitumor agents. Flavonoids are a class of polyphenolic secondary metabolites commonly found in plants and, consequently, consumed in diets. In this review, the systematic search strategy was used, which included the search for descriptors "flavonoids" AND "mTOR pathway" AND "cancer" AND "autophagy", in the electronic databases of PubMed, Cochrane Library, Web of Science and Scopus, from January 2011 to January 2021. The current literature demonstrates that flavonoids have anticarcinogenic properties, including inhibition of cell proliferation, induction of apoptosis, autophagy, necrosis, cell cycle arrest, senescence, impaired cell migration, invasion, tumor angiogenesis and reduced resistance to multiple drugs in tumor cells. We demonstrate the available evidence on the roles of flavonoids and autophagy in cancer progression and inhibition. (Registration No. CRD42021243071 at PROSPERO).

Therapeutic effects of icariin and icariside II on diabetes mellitus and its complications

Diabetes mellitus (DM) is a global health issue in the twenty-first century, and there are numerous challenges in preventing and alleviating its chronic complications. The herb Epimedium has beneficial therapeutic effects on various human diseases, including DM. Its major flavonoid component, icariin, has significant anti-DM activity and may help improve pancreatic β-cell dysfunction and insulin resistance. Furthermore, preclinical evidence has shown that icariin and its in vivo bioactive form, icariside II, have preventive and therapeutic effects on several diabetic complications, including diabetic cardiomyopathy, diabetic vascular endothelial disorder, diabetic nephropathy, and diabetic erectile dysfunction. In this review, we present the general and toxicological information concerning icariin and icariside II and review the anti-DM effects of icariin from a molecular perspective. Additionally, we discuss the potential benefits of icariin and icariside II on the important pathological mechanisms of various diabetic complications. Despite positive preclinical evidence, additional investigations are needed before relevant clinical studies can be conducted. Therefore, we conclude with suggestions for future research. Hopefully, this review will provide a comprehensive molecular perspective for future research and product development related to icariin and icariside II in treating DM and diabetic complications.

Icariin as an emerging candidate drug for anticancer treatment: Current status and perspective

Icariin (ICA) is a kind of natural flavonoid compound monomer, which is derived from the extract of dried stems and leaves of Epimedium. Modern pharmacological studies have found that ICA has broad bioactive function in affecting the biological processes of a variety of cancers, including breast cancer, colorectal cancer, hepatocellular carcinoma, esophageal cancer and other cancers, which indicates that ICA has promising application value in the treatment of cancer patients in the future. Nevertheless, the targets and molecular mechanisms of ICA in cancer treatment have not been elucidated in detail. Therefore, in this review, we systematically summarizes the current research progress of ICA in a series of cancers. In particular, an emphasis is placed on the mechanism of ICA and its future development direction, aiming at providing relevant theoretical basis for the development and application of ICA in the future cancer treatment strategies.

Retraction

Han N, Zhang B, Wei X, Yu L. The inhibitory function of icariin in cell model of benign prostatic hyperplasia by upregulation of miR-7. BioFactors. 2023;49:203. https://doi.org/10.1002/biof.1591 This article, published online on 29 November 2019 in Wiley Online Library, has been retracted by agreement between the International Union of Biochemistry and Molecular Biology, the Editor in Chief (Dr. Angelo Azzi), and Wiley Periodicals LLC. The retraction has been agreed following an investigation based on allegations raised by a third party. Evidence for image manipulation was found in figures 1, 3, 4, 5, 6, and 7. As a result, the conclusions of this article are considered to be invalid.

Sanyin Formula Enhances the Therapeutic Efficacy of Paclitaxel in Triple-Negative Breast Cancer Metastases through the JAK/STAT3 Pathway in Mice

Sanyin formula (SYF) is used as a complementary treatment for triple-negative breast cancer (TNBC). The purpose of this study was to identify the potential functional components and clarify the underlying molecular mechanisms of SYF in TNBC. High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to identify the main components of SYF extracts. Network pharmacology and bioinformatic analyses were carried out to identify potential candidate targets of SYF in TNBC. Cell proliferation was determined with a Celigo imaging cytometer. Wound-healing and Transwell assays were adopted to evaluate cell migration. A Transwell cell-invasion assay was performed with Matrigel-coated membranes. In vivo bioluminescence imaging (BLI) and pathological analyses illustrated the effect of SYF on cancer cell metastasis in tumour-bearing mice. The inhibitory mechanism of SYF was investigated via quantitative PCR (qPCR) and Western blotting. We found that 3,4-dihydroxyphenyllactic acid, kaempferol, p-coumaric acid, and vanillic acid may be the active components of SYF. Molecular docking confirmed that kaempferol, p-coumaric acid, vanillic acid, and 3,4-dihydroxyphenyllactic acid bound stably to proteins such as AKR1C3, MMPs, and STAT3. SYF extract suppressed TNBC cell proliferation, migration, invasion, and metastasis by inhibiting JAK/STAT3 signalling and then regulating downstream genes, such as MMP-2/MMP-9. SYF regulates the expression of genes involved in cell proliferation, migration, and invasion by regulating the JAK/STAT3 signalling pathway and finally inhibits tumour cell metastasis in TNBC. The present study clarifies the mechanism by which SYF inhibits TNBC metastasis and lays an experimental foundation for the continued clinical development of SYF targeting the JAK/STAT3 pathway.

Icariin-Mediated miR-875-5p Inhibits Autophagy and Epithelial-Mesenchymal Transition by Regulation of MDM4 in Cervical Cancer

MicroRNAs, one type of non-coding RNA, and Icariin have attracted tremendous attention concerning various diseases, especially cancers. Also, the function of Icariin on malignant behaviors by targeting miR-875-5p/MDM4 axis in cervical cancer remains unknown. MiR-875-5p analogs combined with MDM4 or Icariin were used to explore autophagy and epithelial-mesenchymal transition in cancer cells. Xenograft mice were highlighted to elucidate the influences of Icariin and miR-875-5p in vivo. As a result, miR-875-5p was cut down in cervical cancer cells, which promoted malignant phenotype, autophagy, and limited apoptosis in cervical cancer cells. Contrarily,miR-875-5p overexpression had a contrary performance in cervical cancer cells. miR-875-5p was validated as a sponge of MDM4. Enhanced expression of MDM4 weakened the performance of miR-875-5p mimic on autophagy and epithelial-mesenchymal transition. Moreover, Icariin reversed the stimulative action of the inhibitor on autophagy and xenograft tumor growth. Generally, These findings imply that Icariin could be identified as a curative avenue for cervical cancer via miR-875-5p/MDM4 axis.

Focusing on the Role of Natural Products in Overcoming Cancer Drug Resistance: An Autophagy-Based Perspective

Autophagy is a critical cellular adaptive response in tumor formation. Nutritional deficiency and hypoxia exacerbate autophagic flux in established malignancies, promoting tumor cell proliferation, migration, metastasis, and resistance to therapeutic interventions. Pro-survival autophagy inhibition may be a promising treatment option for advanced cancer. Furthermore, excessive or persistent autophagy is cytotoxic, resulting in tumor cell death. Targeted autophagy activation has also shown significant promise in the fight against tumor drug resistance. Several research groups have examined the ability of natural products (NPs) such as alkaloids, terpenoids, polyphenols, and anthraquinones to serve as autophagy inhibitors or activators. The data support the capacity of NPs that promote lethal autophagy or inhibit pro-survival autophagy from being employed against tumor drug resistance. This paper discusses the potential applications of NPs that regulate autophagy in the fight against tumor drug resistance, some limitations of the current studies, and future research needs and priorities.

MED16 Promotes Tumour Progression and Tamoxifen Sensitivity by Modulating Autophagy through the mTOR Signalling Pathway in ER-Positive Breast Cancer

Recent studies have shown that the mediator complex (MED) plays a vital role in tumorigenesis and development, but the role of MED16 (mediator complex subunit 16) in breast cancer (BC) is not clear. Increasing evidence has shown that the mTOR pathway is important for tumour progression and therapy. In this study, we demonstrated that the mTOR signalling pathway is regulated by the expression level of MED16 in ER+ breast cancer. With the analysis of bioinformatics data and clinical specimens, we revealed an elevated expression of MED16 in luminal subtype tumours. We found that MED16 knockdown significantly inhibited cell proliferation and promoted G1 phase cell cycle arrest in ER+ BC cell lines. Downregulation of MED16 markedly reduced the sensitivity of ER+ BC cells to tamoxifen and increased the stemness and autophagy of ER+ BC cells. Bioinformatic analysis of similar genes to MED16 were mainly enriched in autophagy, endocrine therapy and mTOR signalling pathways, and the inhibition of mTOR-mediated autophagy restored sensitivity to tamoxifen by MED16 downregulation in ER+ BC cells. These results suggest an important role of MED16 in the regulation of tamoxifen sensitivity in ER+ BC cells, crosstalk between the mTOR signalling pathway-induced autophagy, and together, with the exploration of tamoxifen resistance, may indicate a new therapy option for endocrine therapy-resistant patients.

Cyclin-dependent kinases in breast cancer: expression pattern and therapeutic implications

Presently, breast cancer (BC) is one of the most common malignancies diagnosed and the leading cause of tumor-related deaths among women worldwide. Cell cycle dysregulation is one of the hallmarks of cancer, resulting in uncontrolled cell proliferation. Cyclin-dependent kinases (CDKs) are central to the cell cycle control system, and deregulation of these kinases leads to the development of malignancies, including breast cancer. CDKs and cyclins have been reported as crucial components involved in tumor cell proliferation and metastasis. Given the aggressive nature, tumor heterogeneity, and chemoresistance, there is an urgent need to explore novel targets and therapeutics to manage breast cancer effectively. Inhibitors targeting CDKs modulate the cell cycle, thus throwing light upon their therapeutic aspect where the progression of tumor cells could be inhibited. This article gives a comprehensive account of CDKs in breast cancer progression and metastasis and recent developments in the modulation of CDKs in treating malignancies. We have also explored the expression pattern and prognostic significance of CDKs in breast cancer patients. The article will also shed light on the Implications of CDK inhibition and TGF-β signaling in breast cancer.

Tumor-derived extracellular vesicles containing long noncoding RNA PART1 exert oncogenic effect in hepatocellular carcinoma by polarizing macrophages into M2

AIM

We explored whether tumor-derived extracellular vesicles (EVs) could deliver long noncoding RNA (lncRNA) PART1 into macrophage to orchestrate macrophage polarization in the progression of hepatocellular carcinoma (HCC).

METHOD

The expression patterns of PART1, microRNA (miR)-372-3p and TLR4 were detected by RT-qPCR in the HCC tissues and HCC cells. PART1 was silenced or overexpressed in HCC cells to assess its effects on the HCC cell process. EVs were isolated from PART1-overexpressed HCC cells, and co-cultured with macrophages, and gain- and loss-of-function assays were implemented in macrophages to evaluate their role in macrophage polarization. Relationship among PART1, miR-372-3p, and TLR4 was evaluated. Effect of EV-PART1 on tumorigenicity in vivo was detected by subcutaneous tumorigenicity test in nude mice.

RESULT

PART1 and TLR4 were upregulated while miR-372-3p was downregulated in HCC tissues and cells. PART1 increased HCC cell proliferation, migration, invasion, and EMT. Mechanistically, PART1 bound to miR-372-3p to downregulate its expression, whereas TLR4 was negatively targeted by miR-372-3p in the macrophages. EVs containing PART1, TLR4 overexpression, or miR-372-3p inhibition induced M2 polarization of macrophages. Also, EVs containing PART1 promoted M2 polarization of macrophages and the occurrence of HCC by affecting miR-372-3p/TLR4 axis.

CONCLUSION

HCC cell-derived EVs might up-regulate TLR4 by inhibiting miR-372-3p via PART1 delivery to promote macrophage M2 polarization in HCC.

Promoting Apoptosis, a Promising Way to Treat Breast Cancer With Natural Products: A Comprehensive Review

Breast cancer is one of the top-ranked malignant carcinomas associated with morbidity and mortality in women worldwide. Chemotherapy is one of the main approaches to breast cancer treatment. Breast cancer initially responds to traditional first- and second-line drugs (aromatase inhibitor, tamoxifen, and carboplatin), but eventually acquires resistance, and certain patients relapse within 5 years. Chemotherapeutic drugs also have obvious toxic effects. In recent years, natural products have been widely used in breast cancer research because of their low side effects, low toxicity, and good efficacy based on their multitarget therapy. Apoptosis, a programmed cell death, occurs as a normal and controlled process that promotes cell growth and death. Inducing apoptosis is an important strategy to control excessive breast cancer cell proliferation. Accumulating evidence has revealed that natural products become increasingly important in breast cancer treatment by suppressing cell apoptosis. In this study, we reviewed current studies on natural product–induced breast cancer cell apoptosis and summarized the proapoptosis mechanisms including mitochondrial, FasL/Fas, PI3K/AKT, reactive oxygen species, and mitogen-activated protein kinase–mediated pathway. We hope that our review can provide direction in the search for candidate drugs derived from natural products to treat breast cancer by promoting cell apoptosis.

Cardioprotective effect of icariin against myocardial fibrosis and its molecular mechanism in diabetic cardiomyopathy based on network pharmacology: Role of ICA in DCM

BACKGROUND

Diabetic cardiomyopathy (DCM) is one of the most severe symptoms of diabetes. It continues to be a major clinical problem, but our knowledge of its molecular mechanisms and effective treatments are limited. Traditional Chinese medicine has been shown to be a pool of novel drugs for diabetes.

PURPOSE

Herein, we aim to define the molecular mechanism of icariin (ICA), an extract from a traditional Chinese medicine herb, in protecting cardiac structures and restoring cardiac functions of in a rat model of type 2 diabetes mellitus (T2DM).

STUDY DESIGN AND METHODS

Candidate genes related to T2DM were identified through bioinformatics screening and their interactions were constructed by molecule docking technique, followed by pathway enrichment analyses of their cellular functions. A T2DM rat model was then established to evaluate the effects of ICA on cardiac structures, myocardial fibrosis, and cellular Ca²⁺ inflow, as reflected by HE and Masson staining, qRT-PCR and Western blot determination of related genes, and measurement of the L-type Ca²⁺ current.

RESULTS

Four potential target genes (Jun, p65, NOS3, and PDE5A) were identified. ICA ameliorated the structural damage and myocardial fibrosis in T2DM rats. Intracellular Ca2+ hyperactivities and dysfunction in myocardium of T2DM rats were also repressed by ICA treatment. Furthermore, ICA-induced inhibition of Jun and p65 ameliorated the irregular collagen metabolism and myocardial fibrosis. NOS3, PDE5A and the related sGC-cGMP-PKG signaling pathway mediated the ICA-induced improvement of intracellular Ca²⁺ inflow.

CONCLUSION

In conclusion, these results demonstrate the regulatory roles of potential target genes in DCM and suggest ICA as an effective treatment of DCM by targeting these genes specifically.

Microbial transformation of icariin and its derivatives

Microbial transformation is an important tool to perform selective conversion of compounds to derivatives which are difficult to produce synthetically. In order to obtain icariside II and icaritin, the active components in Herba Epimedii in vivo, biotransformation studies using microbes as biocatalysts were carried out. Icariside II (2) and icaritin (3) were produced through biotransformation of icariin (1) using the fungi Hormoconis resinae and Mortierella ramanniana var. angulispora in 98% and 92% yields, respectively. In the subsequent transformation studies, 2 was deglycosylated to form 3 by Gliocladium deliquescens, whereas 3 was further converted to a novel compound icaritin-3-O-β-d-glucopyranoside (4) and previously known icaritin-3,7-O-β-d-diglucopyranoside (5) by Mucor hiemalis. Biological evaluation of these compounds using MTT assay exhibited potent cytotoxic activities against human cancer cell lines A549, A375P, and MCF-7, with icariin being the most active, indicating that glycosylation plays a role in the cytotoxic activity.

Icariin, an Up-and-Coming Bioactive Compound Against Neurological Diseases: Network Pharmacology-Based Study and Literature Review

Icariin is a biologically active substance in Epimedii herba that is used for the treatment of neurologic disorders. However, a comprehensive analysis of the molecular mechanisms of icariin is lacking. In this review, we present a brief history of the use of icariin for medicinal purposes; describe the active chemical components of Epimedii herba; and examine the evidence from experimental studies that have uncovered molecular targets of icariin in different diseases. We also constructed a protein–protein interaction network and carried out Gene Ontology and Kyoto Encyclopedia of Genes and Genomes functional enrichment analyses to predict the therapeutic actions of icariin in nervous system diseases including Alzheimer disease, Parkinson disease, ischemic stroke, depressive disorder, multiple sclerosis, glioblastoma, and hereditary spastic paraplegias. The results of our analyses can guide future studies on the application of icariin to the treatment of neurologic disorders.

Essential role of protein kinase C βI in icariin-mediated protection against atherosclerosis

OBJECTIVES

This study aimed to clarify the superior beneficial effects of icariin on atherosclerosis, as well as to explore the possible underlying mechanisms for its effect via the modulation of protein kinase C βI.

METHODS

Lipid profiles were determined while dissected aortas were prepared of ApoE-/- mice. The expression of protein kinase C βI and phosphorylation of protein kinase C βI were determined by immunohistochemistry analysis. Human vascular smooth muscle cells were subjected to ox-LDL stimulation. MTS assay was conducted to detect cell proliferation. A transwell migration assay was performed to evaluate migration capacity. Flow cytometric analysis was used to determine cell cycle progression. Quantitative real-time PCR and western blot were performed to assess gene expression.

RESULTS

Icariin significantly alleviated atherogenesis, as well as protein levels of protein kinase C βI and phosphorylated protein kinase C βI in the aorta. Icariin effectively suppressed cell proliferation and migration. protein kinase C βI, cyclin D1 and matrix metalloproteinase-9 were modulated in response to treatment with icariin. Protein kinase C activator reversed the protective effect of icariin on human vascular smooth muscle cells against ox- low-density lipoprotein, protein kinase C β inhibitor augmented the inhibitory effect of icariin.

CONCLUSIONS

Our findings highlight the probable application of icariin in atherosclerotic therapy and reveal that protein kinase C βI acts as a crucial regulator in the anti-atherosclerotic action of icariin.

MicroRNAs involved in drug resistance of breast cancer by regulating autophagy

Autophagy is a conserved catabolic process characterized by degradation and recycling of cytosolic components or organelles through a lysosome-dependent pathway. It has a complex and close relationship to drug resistance in breast cancer. MicroRNAs (miRNAs) are small noncoding molecules that can influence numerous cellular processes including autophagy, through the posttranscriptional regulation of gene expression. Autophagy is regulated by many proteins and pathways, some of which in turn have been found to be regulated by miRNAs. These miRNAs may affect the drug resistance of breast cancer. Drug resistance is the main cause of distant recurrence, metastasis and death in breast cancer patients. In this review, we summarize the causative relationship between autophagy and drug resistance of breast cancer. The roles of autophagy-related proteins and pathways and their associated miRNAs in drug resistance of breast cancer are also discussed.

Cyclin-Dependent Kinase 4 and 6 Inhibitors in Cell Cycle Dysregulation for Breast Cancer Treatment

In cell development, the cell cycle is crucial, and the cycle progression’s main controllers are endogenous CDK inhibitors, cyclin-dependent kinases (CDKs), and cyclins. In response to the mitogenic signal, cyclin D is produced and retinoblastoma protein (Rb) is phosphorylated due to activated CDK4/CDK6. This causes various proteins required in the cell cycle progression to be generated. In addition, complexes of CDK1-cyclin A/B, CDK2-cyclin E/A, and CDK4/CDK6-cyclin D are required in each phase of this progression. Cell cycle dysregulation has the ability to lead to cancer. Based on its role in the cell cycle, CDK has become a natural target of anticancer therapy. Therefore, understanding the CDK structures and the complex formed with the drug, helps to foster the development of CDK inhibitors. This development starts from non-selective CDK inhibitors to selective CDK4/CDK6 inhibitors, and these have been applied in clinical cancer treatment. However, these inhibitors currently require further development for various hematologic malignancies and solid tumors, based on the results demonstrated. In drug development, the main strategy is primarily to prevent and asphyxiate drug resistance, thus a determination of specific biomarkers is required to increase the therapy’s effectiveness as well as patient selection suitability in order to avoid therapy failure. This review is expected to serve as a reference for early and advanced-stage researchers in designing new molecules or repurposing existing molecules as CDK4/CDK6 inhibitors to treat breast cancer.

Autophagy-related signaling pathways are involved in cancer (Review)

Autophagy is a self-digestion process in cells that can maintain energy homeostasis under normal circumstances. However, misfolded proteins, damaged mitochondria and other unwanted components in cells can be decomposed and reused via autophagy in some specific cases (including hypoxic stress, low energy states or nutrient deprivation). Therefore, autophagy serves a positive role in cell survival and growth. However, excessive autophagy may lead to apoptosis. Furthermore, abnormal autophagy may lead to carcinogenesis and promote tumorigenesis in normal cells. In tumor cells, autophagy may provide the energy required for excessive proliferation, promote the growth of cancer cells, and evade apoptosis caused by certain treatments, including radiotherapy and chemotherapy, resulting in increased treatment resistance and drug resistance. On the other hand, autophagy leads to an insufficient nutrient supply in cancer cells and the destruction of energy homeostasis, thereby inducing cancer cell apoptosis. Therefore, understanding the mechanism of the double-edged sword of autophagy is crucial for the treatment of cancer. The present review summarizes the signaling pathways and key factors involved in autophagy and cancer to provide possible strategies for treating tumors.

Isolation, characterization and in vitro cytotoxicity studies of bioactive compounds from Alseodaphne semecarpifolia Nees

Alseodaphne semecarpifolia (Lauraceae) is a traditional medicinal plant historically used in Indian Western Ghats to treat various human diseases. From the past few decades it has been traditionally recognized as an effective agent in cancer treatment. The phytochemical investigation of the stem bark and leaves of A. semecarpifolia led to the isolation of bioactive flavonoid compounds Icariin and Baicalein. Their structures were elucidated from obtained spectral data (¹H NMR, ¹³C NMR, ¹H ¹H COSY, FTIR and MS). Cytotoxic activity of Icariin and Baicalein evaluated against MCF-7 cells revealed their potent activity with an IC₅₀ of 42.15 ± 4.78 μg/ml and 44.37 ± 3.46 μg/ml, respectively, while very least effect was observed on normal cells (L6). Present study has suggested that both Icariin and Baicalein have potent cytotoxic activity against MCF-7 cells.

Therapeutic effects and mechanism of ferulic acid and icariin in mammary gland hyperplasia model rats via regulation of the ERK pathway

Background

Ferulic acid (FA) and icariin (ICA), as the active compounds derived from Angelica sinensis and Epimedium brevicornum Maxim, respectively, have been shown to promote blood circulation, regulate menstruation, exhibit anti-inflammatory effects, and modulate estrogen levels. The aim of this study was to elucidate the possible mechanism of FA, ICA, and FA-ICA on estrogen-induced mammary gland hyperplasia (MGH) in rats.

Methods

Hematoxylin and eosin (HE) staining was performed to record the pathological changes in breast tissue, and enzyme-linked immunosorbent assay (ELISA) was utilized to determine the serum levels of luteinizing hormone (LH), PRL (prolactin), testosterone (T), estradiol (E2), follicular stimulating hormone (FSH), and progesterone (P). The message RNA (mRNA) expression levels of extracellular signal-regulated kinase 1 (ERK1), extracellular signal-regulated kinase 2 (ERK2), estrogen receptor (ER), and progesterone receptor (PR) were detected by real-time reverse transcription-polymerase chain reaction (RT-PCR) analysis. Furthermore, ER, phosphorylated-ER, PR, p-PR, ERK1/2, and p-ERK1/2 protein factors in the ERK signaling pathway were evaluated by Western blotting. Simultaneously, changes in breast height, diameter, body weight, and organ index were all recorded.

Results

We found that FA and ICA could modulate the degree of breast swelling, and reduce the body weight, thymus index, and uterus index. Furthermore, it could also block the pathological changes of MGH, including the number of mammary lobules, and the proliferation or expansion of acini and ducts. Moreover, treatment with FA and ICA remarkably down-regulated the serum expression levels of LH, PRL, T, and E2, as well as the mRNA expression levels of ERα, PR, ERK1, and ERK2. Additionally, protein levels of ERα, p-ERα, PR, p-PR, ERK1/2, and p-ERK1/2 in breast tissue were down-regulated, however the serum content of FSH and P was up-regulated.

Conclusions

Our outcomes revealed that FA and ICA might potentially inhibit ERα, PR, ERK1/2, and their phosphorylated proteins via the ERK signaling pathway, thus indicating a positive feedback control for the degree of breast hyperplasia.

FV-429 induces autophagy blockage and lysosome-dependent cell death of T-cell malignancies via lysosomal dysregulation

It is widely accepted that lysosomes are essential for cell homeostasis, and autophagy plays an important role in tumor development. Here, we found FV-429, a synthetic flavonoid compound, inhibited autophagy flux, promoted autophagosomes accumulation, and inhibited lysosomal degradation in T-cell malignancies. These effects were likely to be achieved by lysosomal dysregulation. The destructive effects of FV-429 on lysosomes resulted in blockage of lysosome-associated membrane fusion, lysosomal membrane permeabilization (LMP), and cathepsin-mediated caspase-independent cell death (CICD). Moreover, we initially investigated the effects of autophagy inhibition by FV-429 on the therapeutic efficacy of chemotherapy and found that FV-429 sensitized cancer cells to chemotherapy agents. Our findings suggest that FV-429 could be a potential novel autophagy inhibitor with notable antitumor efficacy as a single agent.

Optimized Icariin Cubosomes Exhibit Augmented Cytotoxicity against SKOV-3 Ovarian Cancer Cells

Clinical application of icariin (ICA) is limited, despite its activity against cancer growth, because of the low solubility of ICA in an aqueous environment. Therefore, the present study attempted to develop and optimize ICA-loaded cubosome delivery and to explore its efficacy and possible mechanism of action against ovarian cancer. The optimization of the cubosome formulation was performed using the Box‒Behnken statistical design; during the characterization, the particle sizes were in the range of 73 to 183 nm and the entrapment efficiency was 78.3% to 97.3%. Optimized ICA-loaded cubosomes (ICA-Cubs) exhibited enhanced cytotoxicity and apoptotic potential, compared with ICA-raw, against ovarian cancer cell lines (SKOV-3 and Caov 3). The optimized ICA-Cubs showed a relatively non-cytotoxic effect on normal EA.hy926 endothelial cells. Further analysis of cell cycle arrest suggested a potential role in the pre-G1 and G2/M phases for ICA-Cubs in comparison with ICA-raw. ICA-Cubs increased the generation of reactive oxygen species (ROS) and the overexpression of p53 and caspase-3 in the SKOV-3 cell line. In conclusion, the cubosomal delivery of ICA might provide a prospective approach towards the superior control of ovarian cancer cell growth. Its improved efficacy compared with that of the free drug might be due to the improved solubility and cellular permeability of ICA.

miR-30d-5p suppresses proliferation and autophagy by targeting ATG5 in renal cell carcinoma

Previous reports have shown that miR-30d-5p functions as a tumor suppressor in prostate cancer and gallbladder carcinoma, but its role in renal cell carcinoma (RCC) remains elusive. This study was designed to explore the functional role of miR-30d-5p in proliferation and autophagy of RCC. Our results show that miR-30d-5p is significantly down-regulated in RCC tissues compared with normal tissues. miR-30d-5p overexpression suppressed cell proliferation, cell-cycle G1/S transition and autophagy, but promoted apoptosis in RCC cell lines (786-O and ACHN). Intriguingly, autophagy-related gene 5 (ATG5) was directly targeted by miR-30d-5p, as shown using luciferase reporter assay and biotin-avidin pull-down assay. Moreover, overexpression of ATG5 attenuated the inhibitory effect of miR-30d-5p on proliferation and autophagy in 786-O cells. These results suggest that miR-30d-5p suppresses proliferation and autophagy in RCC cells by targeting ATG5, and this pathway may be a suitable basis for the design of novel cancer therapeutics.

Progress in the Understanding of the Mechanism of Tamoxifen Resistance in Breast Cancer

Tamoxifen is a drug commonly used in the treatment of breast cancer, especially for postmenopausal patients. However, its efficacy is limited by the development of drug resistance. Downregulation of estrogen receptor alpha (ERα) is an important mechanism of tamoxifen resistance. In recent years, with progress in research into the protective autophagy of drug-resistant cells and cell cycle regulators, major breakthroughs have been made in research on tamoxifen resistance. For a better understanding of the mechanism of tamoxifen resistance, protective autophagy, cell cycle regulators, and some transcription factors and enzymes regulating the expression of the estrogen receptor are summarized in this review. In addition, recent progress in reducing resistance to tamoxifen is reviewed. Finally, we discuss the possible research directions into tamoxifen resistance in the future to provide assistance for the clinical treatment of breast cancer.

Mechanistic studies of cytotoxic activity of the mesoionic compound MIH 2.4Bl in MCF-7 breast cancer cells

In the present study, the cytotoxic effects of a 1,3-thiazolium-5-thiolate derivative of a mesoionic compound, MIH 2.4Bl, were assessed in the MCF-7 breast cancer cell line. The cytotoxic effects of MIH 2.4Bl were determined using a crystal violet assay. Using a dose-response curve, the IC₅₀ value of MIH 2.4Bl was determined to be 45.8±0.8 µM. Additionally, the effects of MIH 2.4Bl on mitochondrial respiration were characterized using oxygen consumption rate analysis. Treating MCF-7 cells with increasing concentrations of MIH 2.4Bl resulted in a significant reduction in all mitochondrial respiratory parameters compared with the control cells, indicative of an overall decrease in mitochondrial membrane potential. The induction of autophagy by MIH 2.4Bl was also examined by measuring changes in the expression of protein markers of autophagy. As shown by western blot analysis, treatment of MCF-7 cells with MIH 2.4Bl resulted in increased protein expression levels of Beclin-1 and ATG5, as well as an increase in the microtubule-associated protein 1A/1B light chain 3B (LC3B)-II to LC3B-I ratio compared with the control cells. Microarray analysis of changes in gene expression following MIH 2.4Bl treatment demonstrated 3,659 genes exhibited a fold-change ≥2. Among these genes, 779 were up-regulated, and 2,880 were down-regulated in cells treated with MIH 2.4Bl compared with the control cells. Based on the identity of the transcripts and fold-change of expression, six genes were selected for verification by reverse transcription-quantitative (RT-q)PCR; activating transcription factor 3, acidic repeat-containing protein, heparin-binding EGF-like growth factor, regulator of G-protein signaling 2, Dickkopf WNT signaling pathway inhibitor 1 and adhesion molecule with Ig like domain 2. The results of RT-qPCR analysis of RNA isolated from control and MIH 2.4Bl treated cells were consistent with the expression changes identified by microarray analysis. Together, these results suggest that MIH 2.4Bl may be a promising candidate for treating breast cancer and warrants further in vitro and in vivo investigation.

Molecular and cellular basis of the anticancer activity of the prenylated flavonoid icaritin in hepatocellular carcinoma

The prenylated flavonoid icaritin (ICT) is currently undergoing phase 3 clinical trial for the treatment of advanced hepatocellular carcinoma (HCC), based on a solid array of preclinical and clinical data. The antitumor activity originates from the capacity of the drug to modulate several signaling effectors in cancer cells, mainly the estrogen receptor splice variant ERα36, the transcription factors STAT3 and NFκB, and the chemokine receptor CXCR4. Recent studies have implicated additional components, including different microRNAs, the generation of reactive oxygen species and the targeting of sphingosine kinase-1. ICT also engages the RAGE-HMGB1 signaling route and modulates the apoptosis/autophagy crosstalk to promote its anticancer activity. In addition, ICT exerts profound changes on the tumor microenvironment to favor an immune-response. Collectively, these multiple biochemical and cellular characteristics confer to ICT a robust activity profile which can be exploited to treat HCC, as well as other cancers, including glioblastoma and onco-hematological diseases such as chronic myeloid leukemia. This review provides an update of the pharmacological properties of ICT and its metabolic characteristics. It also addresses the design of derivatives, including both natural products and synthetic molecules, such as SNG1153 also in clinical trial. The prenylated flavonoid ICT deserves attention as a multifunctional natural product potentially useful to improve the treatment of advanced hepatocellular carcinoma.

Icariin affects cell cycle progression and proliferation of human retinal pigment epithelial cells via enhancing expression of H19

Background

Aberrant proliferation of retinal pigment epithelial (RPE) cells under pathologic condition results in the occurrence of proliferative vitreoretinopathy (PVR). Icariin (ICA)-a flavonol glucoside-has been shown to inhibit proliferation of many cell types, but the effect on RPE cells is unknown. This study aimed to clarify the inhibitory effects of ICA on RPE cells against platelet-derived growth factor (PDGF)-BB-induced cell proliferation, and discuss the regulatory function of H19 in RPE cells.

Methods

MTS assay was conducted to determine the effects of ICA on cell proliferation. Flow cytometry analysis was performed to detect cell cycle progression. Quantitative real-time PCR and western blot assay were used to measure the expression patterns of genes in RPE cells.

Results

ICA significantly suppressed PDGF-BB-stimulated RPE cell proliferation in a concentration-dependent manner. Moreover, since administration of ICA induced cell cycle G0/G1 phase arrest, the anti-proliferative activity of ICA may be due to G0/G1 phase arrest in RPE cells. At molecular levels, cell cycle regulators cyclin D1, CDK4, CDK6, p21 and p53 were modulated in response to treatment with ICA. Most importantly, H19 was positively regulated by ICA and H19 depletion could reverse the inhibitory effects of ICA on cell cycle progression and proliferation in PDGF-BB-stimulated RPE cells. Further mechanical explorations showed that H19 knockdown resulted in alternative expressions levels of cyclin D1, CDK4, CDK6, p21 and p53 under ICA treatment.

Conclusions

Our findings revealed that ICA was an effective inhibitor of PDGF-BB-induced RPE cell proliferation through affecting the expression levels of cell cycle-associated factors, and highlighted the potential application of ICA in PVR therapy. H19 was described as a target regulatory gene of ICA whose disruption may contribute to excessive proliferation of RPE cells, suggesting that modulation of H19 expression may be a novel therapeutic approach to treat PVR.

The Roles of Cyclin-Dependent Kinases in Cell-Cycle Progression and Therapeutic Strategies in Human Breast Cancer

Cyclin-dependent kinases (CDKs) are serine/threonine kinases whose catalytic activities are regulated by interactions with cyclins and CDK inhibitors (CKIs). CDKs are key regulatory enzymes involved in cell proliferation through regulating cell-cycle checkpoints and transcriptional events in response to extracellular and intracellular signals. Not surprisingly, the dysregulation of CDKs is a hallmark of cancers, and inhibition of specific members is considered an attractive target in cancer therapy. In breast cancer (BC), dual CDK4/6 inhibitors, palbociclib, ribociclib, and abemaciclib, combined with other agents, were approved by the Food and Drug Administration (FDA) recently for the treatment of hormone receptor positive (HR+) advanced or metastatic breast cancer (A/MBC), as well as other sub-types of breast cancer. Furthermore, ongoing studies identified more selective CDK inhibitors as promising clinical targets. In this review, we focus on the roles of CDKs in driving cell-cycle progression, cell-cycle checkpoints, and transcriptional regulation, a highlight of dysregulated CDK activation in BC. We also discuss the most relevant CDK inhibitors currently in clinical BC trials, with special emphasis on CDK4/6 inhibitors used for the treatment of estrogen receptor-positive (ER+)/human epidermal growth factor 2-negative (HER2−) M/ABC patients, as well as more emerging precise therapeutic strategies, such as combination therapies and microRNA (miRNA) therapy.