Combination treatment of docetaxel with caffeic acid phenethyl ester suppresses the survival and the proliferation of docetaxel-resistant prostate cancer cells via induction of apoptosis and metabolism interference

Prostate cancer cells elevate glycolysis and G6PD in response to caffeic acid phenethyl ester-induced growth inhibition

BACKGROUND

Caffeic acid phenethyl ester (CAPE) is the main bioactive component of poplar type propolis. We previously reported that treatment with caffeic acid phenethyl ester (CAPE) suppressed the cell proliferation, tumor growth, as well as migration and invasion of prostate cancer (PCa) cells via inhibition of signaling pathways of AKT, c-Myc, Wnt and EGFR. We also demonstrated that combined treatment of CAPE and docetaxel altered the genes involved in glycolysis and tricarboxylic acid (TCA) cycle. We therefore suspect that CAPE treatment may interfere glucose metabolism in PCa cells.

METHODS

Seahorse Bioenergetics platform was applied to analyzed the extra cellular acidification rate (ECAR) and oxygen consumption rate (OCR) of PCa cells under CAPE treatment. UPLC-MSMS with Multiple Reaction Monitoring (MRM), PCR, and western blot were used to analyze the effects of CAPE on metabolites, genes, and proteins involved in glycolysis, TCA cycle and pentose phosphate pathway in PCa cells. Flow cytometry and ELISA were used to determine the level of reactive oxygen species in PCa cells being treated with CAPE.

RESULTS

Seahorse Bioenergetics analysis revealed that ECAR, glycolysis, OCR, and ATP production were elevated in C4-2B cells under CAPE treatment. Protein levels of glucose-6-phosphate dehydrogenase (G6PD), phosphogluconate dehydrogenase (PGD), glutaminase (GLS), phospho-AMPK Thr172 as well as abundance of pyruvate, lactate, ribulose-5-phosphate, and sedoheptulose-7-phosphate were increased in CAPE-treated C4-2B cells. ROS level decreased 48 h after treatment with CAPE. Co-treatment of AMPK inhibitor with CAPE exhibited additive growth inhibition on PCa cells.

CONCLUSIONS

Our study indicated that PCa cells attempted to overcome the CAPE-induced stress by upregulation of glycolysis and G6PD but failed to impede the growth inhibition caused by CAPE. Concurrent treatment of CAPE and inhibitors targeting glycolysis may be effective therapy for advanced PCa.

Analysis and functional validations of multiple cell death patterns for prognosis in prostate cancer

Prostate cancer (PCa) has garnered significant attention due to its rising incidence, variable therapeutic outcomes, and the absence of reliable prognostic markers. The significance of different cell death patterns in tumor development underscores their potential as predictors of PCa prognosis. This study utilized The Cancer Genome Atlas (TCGA) datasets to evaluate the prognostic capabilities of 15 cell death patterns and established a Cell Death Index (CDI) signature based on necrosis and cuproptosis-related genes. The predictive efficacy of the CDI signature was validated in our PCa cohort and in two public datasets: Deutsches Krebsforschungszentrum (DKFZ) and Memorial Sloan-Kettering Cancer Center (MSKCC) PCa cohorts. Our comprehensive analysis examined the relationship between CDI signature and clinical characteristics, published prognostic signatures, gene mutations, immune cell infiltration, enrichment pathways, and drug sensitivity in PCa. In vitro and in vivo studies assessed the impact of EDA2R and LOXL2 on PCa progression. The CDI signature exhibited robust predictive performance across three independent validation sets, with 1-, 2-, 3-, 4-, and 5-year area under the curve (AUC) values in the TCGA cohort of 0.866, 0.77, 0.836, 0.776, and 0.787, respectively. Higher CDI scores were correlated with advanced T and N stages, elevated Gleason scores, increased immune cell infiltration, gene mutations, and drug sensitivity. EDA2R inhibited PCa cell proliferation and migration, related to tumor necrosis, while LOXL2 promoted these processes and was associated with cuproptosis. In summary, our study identified a novel CDI signature as an effective indicator for diagnosis, personalized treatment, and prognostic assessment in PCa.

A Novel PPARγ Modulator Falcarindiol Mediates ER Stress-Mediated Apoptosis by Regulating NOX4 and Overcomes Radioresistance in Breast Cancer

The extract of the rhizome of Cnidium officinale Makino has potential anti-cancer and anti-inflammatory effects in many diseases, such as cancer. However, the biological functions of falcarindiol (FAD) in breast cancer are not fully understood. This study proved the anti-inflammatory and anti-cancer effects of FAD in breast cancer. Breast cancer models confirmed that FAD reduces cell viability and decreases the tumor volume of xenograft mouse models in a dose-dependent manner. FAD mediated caspase-3-dependent apoptosis in MDA-MB-231 and MCF-7 cells, whereas Z-VAD-FMK in combination with FAD inhibited caspase-3-induced apoptosis. FAD mediates apoptosis through cytosolic reactive oxygen species (ROS) and calcium (Ca2+) production and ER stress signaling pathways. In addition, FAD combined with thapsigargin (TG) exerts a synergistic apoptotic cell death effect. In the loss-of-function experiments, PERK or CHOP ablation suppressed intracellular ROS and Ca2+ release and ER stress-induced apoptosis in FAD-treated breast cancer models. Since there is a relationship between ROS and NADPH Oxidase 4 (NOX4), Nox4 ablation blocked ER stress-mediated apoptotic cell death by inhibiting ROS release in FAD-induced breast cancer models. Radioresistant models, such as MCF-7R and MDA-MB-231R, were developed to address the cellular radioresistance in clinical radiotherapy. FAD combined with radiation (2 Gy) overcame radioresistance via the inhibition of the epithelial-mesenchymal transition (EMT) phenomenon, such as the upregulation of PPARγ, VIM, and CDH2 and the downregulation of CDH1. Consequently, these results show that FAD may be a novel treatment as a breast cancer therapy.

Caffeic acid phenethyl ester promotes oxaliplatin sensitization in colon cancer by inhibiting autophagy

Colon cancer ranks as the third most prevalent form of cancer globally, with chemotherapy remaining the primary treatment modality. To mitigate drug resistance and minimize adverse effects associated with chemotherapy, selection of appropriate adjuvants assumes paramount importance. Caffeic acid phenethyl ester (CAPE), a naturally occurring compound derived from propolis, exhibits a diverse array of biological activities. We observed that the addition of CAPE significantly augmented the drug sensitivity of colon cancer cells to oxaliplatin. In SW480 and HCT116 cells, oxaliplatin combined with 10 µM CAPE reduced the IC50 of oxaliplatin from 14.24 ± 1.03 and 84.16 ± 3.02 µM to 2.11 ± 0.15 and 3.92 ± 0.17 µM, respectively. We then used proteomics to detect differentially expressed proteins in CAPE-treated SW480 cells and found that the main proteins showing changes in expression after CAPE treatment were p62 (SQSTM1) and LC3B (MAP1LC3B). Gene ontology analysis revealed that CAPE exerted antitumor and chemotherapy-sensitization effects through the autophagy pathway. We subsequently verified the differentially expressed proteins using immunoblotting. Simultaneously, the autophagy inhibitor bafilomycin A1 and the mCherry-EGFP-LC3 reporter gene were used as controls to detect the effect of CAPE on autophagy levels. Collectively, the results indicate that CAPE may exert antitumor and chemotherapy-sensitizing effects by inhibiting autophagy, offering novel insights for the development of potential chemosensitizing agents.

Epigenetic activation of METTL14 promotes docetaxel resistance in prostate cancer by promoting pri-microRNA-129 maturation

The development of resistance to Docetaxel (DTX) compromises its therapeutic efficacy and worsens the prognosis of prostate cancer (PCa), while the underlying regulatory mechanism remains poorly understood. In this study, METTL14 was found to be upregulated in DTX-resistant PCa cells and PCa tissues exhibiting progressive disease during DTX therapy. Furthermore, overexpression of METTL14 promoted the development of resistance to DTX in both in vitro and in vivo. Interestingly, it was observed that the hypermethylation of the E2F1 targeting site within DTX-resistant PCa cells hindered the binding ability of E2F1 to the promoter region of METTL14, thereby augmenting its transcriptional activity. Consequently, this elevated expression level of METTL14 facilitated m6A-dependent processing of pri-miR-129 and subsequently led to an increase in miR-129-5p expression. Our study highlights the crucial role of the E2F1-METTL14-miR-129-5p axis in modulating DTX resistance in PCa, underscoring METTL14 as a promising therapeutic target for DTX-resistant PCa patients.

Caffeic acid phenethyl ester inhibits neuro-inflammation and oxidative stress following spinal cord injury by mitigating mitochondrial dysfunction via the SIRT1/PGC1α/DRP1 signaling pathway

BACKGROUND

The treatment of spinal cord injury (SCI) has always been a significant research focus of clinical neuroscience, with inhibition of microglia-mediated neuro-inflammation as well as oxidative stress key to successful SCI patient treatment. Caffeic acid phenethyl ester (CAPE), a compound extracted from propolis, has both anti-inflammatory and anti-oxidative effects, but its SCI therapeutic effects have rarely been reported.

METHODS

We constructed a mouse spinal cord contusion model and administered CAPE intraperitoneally for 7 consecutive days after injury, and methylprednisolone (MP) was used as a positive control. Hematoxylin-eosin, Nissl, and Luxol Fast Blue staining were used to assess the effect of CAPE on the structures of nervous tissue after SCI. Basso Mouse Scale scores and footprint analysis were used to explore the effect of CAPE on the recovery of motor function by SCI mice. Western blot analysis and immunofluorescence staining assessed levels of inflammatory mediators and oxidative stress-related proteins both in vivo and in vitro after CAPE treatment. Further, reactive oxygen species (ROS) within the cytoplasm were detected using an ROS kit. Changes in mitochondrial membrane potential after CAPE treatment were detected with 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-imidacarbocyanine iodide. Mechanistically, western blot analysis and immunofluorescence staining were used to examine the effect of CAPE on the SIRT1/PGC1α/DRP1 signaling pathway.

RESULTS

CAPE-treated SCI mice showed less neuronal tissue loss, more neuronal survival, and reduced demyelination. Interestingly, SCI mice treated with CAPE showed better recovery of motor function. CAPE treatment reduced the expression of inflammatory and oxidative mediators, including iNOS, COX-2, TNF-α, IL-1β, 1L-6, NOX-2, and NOX-4, as well as the positive control MP both in vitro and in vivo. In addition, molecular docking experiments showed that CAPE had a high affinity for SIRT1, and that CAPE treatment significantly activated SIRT1 and PGC1α, with down-regulation of DRP1. Further, CAPE treatment significantly reduced the level of ROS in cellular cytoplasm and increased the mitochondrial membrane potential, which improved normal mitochondrial function. After administering the SIRT1 inhibitor nicotinamide, the effect of CAPE on neuro-inflammation and oxidative stress was reversed.On the contrary, SIRT1 agonist SRT2183 further enhanced the anti-inflammatory and antioxidant effects of CAPE, indicating that the anti-inflammatory and anti-oxidative stress effects of CAPE after SCI were dependent on SIRT1.

CONCLUSION

CAPE inhibits microglia-mediated neuro-inflammation and oxidative stress and supports mitochondrial function by regulating the SIRT1/PGC1α/DRP1 signaling pathway after SCI. These effects demonstrate that CAPE reduces nerve tissue damage. Therefore, CAPE is a potential drug for the treatment of SCI through production of anti-inflammatory and anti-oxidative stress effects.

Targeting the Warburg effect: A revisited perspective from molecular mechanisms to traditional and innovative therapeutic strategies in cancer

Cancer reprogramming is an important facilitator of cancer development and survival, with tumor cells exhibiting a preference for aerobic glycolysis beyond oxidative phosphorylation, even under sufficient oxygen supply condition. This metabolic alteration, known as the Warburg effect, serves as a significant indicator of malignant tumor transformation. The Warburg effect primarily impacts cancer occurrence by influencing the aerobic glycolysis pathway in cancer cells. Key enzymes involved in this process include glucose transporters (GLUTs), HKs, PFKs, LDHs, and PKM2. Moreover, the expression of transcriptional regulatory factors and proteins, such as FOXM1, p53, NF-κB, HIF1α, and c-Myc, can also influence cancer progression. Furthermore, lncRNAs, miRNAs, and circular RNAs play a vital role in directly regulating the Warburg effect. Additionally, gene mutations, tumor microenvironment remodeling, and immune system interactions are closely associated with the Warburg effect. Notably, the development of drugs targeting the Warburg effect has exhibited promising potential in tumor treatment. This comprehensive review presents novel directions and approaches for the early diagnosis and treatment of cancer patients by conducting in-depth research and summarizing the bright prospects of targeting the Warburg effect in cancer.

Ultrasound image-guided cancer gene therapy using iRGD dual-targeted magnetic cationic microbubbles

The gene therapy attracted more and more attention for the tumor therapy. To obtain a safe gene therapy system, the new gene vectors beyond the virus were developed for a high gene therapy efficiency. The ultrasound mediated gene therapy was safer and the plasmid DNA could be delivered by the microbubbles and combined with the ultrasound to increase the gene transfection efficiency. In this work, the cationic microbubbles decorated with Cyclo(Cys-Arg-Gly-Asp-Lys-Gly-Pro-AspCys) (iRGD peptides) and magnetic Fe3O4 nanoparticles (MBiM) was designed for targeted ultrasound contrast imaging guided gene therapy of tumors. The ultrasound image intensity was dramatically enhanced at the tumor site that received MBiM with the magnet applied, compared to those administrated the non-targeted microbubbles (MBb) or the microbubbles with only one target material on the surface (MBM and MBbi). The pGPU6/GFP/Neo-shAKT2 was used as a sample gene, which down regulate the AKT2 protein expression for the cancer therapy. It illustrated that MBiM/AKT2 had the highest gene transfection efficiency in the studied microbubbles mediated by the ultrasound, leading to the AKT2 protein expression downregulation and the strongest tumor killing effect in vitro and in vivo. In summary, a novel and biocompatible gene delivery platform via MBiM with both the endogenous and external targeting effects for breast cancer theranostics was developed.

Methylation of GPRC5A promotes liver metastasis and docetaxel resistance through activating mTOR signaling pathway in triple negative breast cancer

AIMS

This study aims to explore the function and mechanism of G Protein-coupled receptor class C group 5 member A (GPRC5A) in docetaxel-resistance and liver metastasis of breast cancer.

METHODS

Single-cell RNA transcriptomic analysis and bioinformatic analysis are used to screen relevant genes in breast cancer metastatic hepatic specimens. MeRIP, dual-luciferase analysis and bioinformation were used to detect m6A modulation. Mass spectrometry (MS), co-inmunoprecipitation (co-IP) and immunofluorescence colocalization were executed to explore the mechanism of GPRC5A in breast cancer cells.

RESULT

GPRC5A was upregulated in triple-negative breast cancer (TNBC) and was associated with a poor prognosis. In vitro and in vivo experiments demonstrated that knockdown of GPRC5A alleviated metastasis and resistance to docetaxel in TNBC. Overexpression of GPRC5A had the opposite effects. The m6A methylation of GPRC5A mRNA was modulated by METTL3 and YTHDF1, which facilitates its translation. GPRC5A inhibited the ubiquitination-dependent degradation of LAMTOR1, resulting in the recruitment of mTORC1 to lysosomes and activating the mTORC1/p70s6k signaling pathway.

CONCLUSION

METTL3/YTHDF1 axis up-regulates GPRC5A expression by m6A methylation. GPRC5A activates mTORC1/p70s6k signaling pathway by recruiting mTORC1 to lysosomes, consequently promotes docetaxel-resistance and liver metastasis.

Exploring the Prospective Role of Propolis in Modifying Aging Hallmarks

Aging populations worldwide are placing age-related diseases at the forefront of the research agenda. The therapeutic potential of natural substances, especially propolis and its components, has led to these products being promising agents for alleviating several cellular and molecular-level changes associated with age-related diseases. With this in mind, scientists have introduced a contextual framework to guide future aging research, called the hallmarks of aging. This framework encompasses various mechanisms including genomic instability, epigenetic changes, mitochondrial dysfunction, inflammation, impaired nutrient sensing, and altered intercellular communication. Propolis, with its rich array of bioactive compounds, functions as a potent functional food, modulating metabolism, gut microbiota, inflammation, and immune response, offering significant health benefits. Studies emphasize propolis' properties, such as antitumor, cardioprotective, and neuroprotective effects, as well as its ability to mitigate inflammation, oxidative stress, DNA damage, and pathogenic gut bacteria growth. This article underscores current scientific evidence supporting propolis' role in controlling molecular and cellular characteristics linked to aging and its hallmarks, hypothesizing its potential in geroscience research. The aim is to discover novel therapeutic strategies to improve health and quality of life in older individuals, addressing existing deficits and perspectives in this research area.

8-Br-cGMP activates HSPB6 and increases the antineoplastic activity of quinidine in prostate cancer

Heat shock protein family B [small] member 6 (HSPB6), widely found in various muscles, has been recently identified as a tumor suppressor gene. However, its role in prostate cancer remains unexplored. Herein, we investigated the expression of HSPB6 in prostate cancer and its association with prognosis. Our findings revealed that HSPB6 downregulation in prostate cancer correlated with a poor prognosis. Moreover, we discovered that HSPB6 can be phosphorylated and activated by 8-Br-cGMP, leading to apoptosis in prostate cancer cells by activating Cofilin. Additionally, we demonstrated that knocking down E2F1 by quinidine administration enhances the transcriptional level of HSPB6. Furthermore, we evaluated the combination of quinidine and 8-Br-cGMP as a potential therapeutic strategy for prostate cancer. Our results revealed that the combined treatment was more effective than either treatment alone in inhibiting the growth of prostate cancer through the HSPB6 pathway, both in vitro and in vivo. Overall, our study provides compelling evidence that HSPB6 suppresses malignant behavior in prostate cancer by inducing apoptosis. The combination of quinidine and 8-Br-cGMP emerges as a promising approach for the treatment of prostate cancer.

Serine/threonine kinase 36 induced epithelial-mesenchymal transition promotes docetaxel resistance in prostate cancer

To investigate the role and potential mechanism of serine/threonine kinase 36 (STK36) in docetaxel resistance-prostate cancer (PCa). The expression of STK36 in PCa and the correlation with clinicopathological characteristics of PCa patients were analyzed using the data from different databases and tissue microarrays. To investigate the role of STK36 on cell proliferation, invasion, and migration, STK36 was overexpressed and silenced in DU-145 and PC-3 cell lines. Cell counting kit-8 (CCK8) was used to test cell proliferation. Cell invasion and migration were detected by cell wound scratch assay and trans well, respectively. The expression profile of STK36, E-Cadherin, and Vimentin was analyzed by Western blot. Cell apoptosis was detected by the TUNEL assay. STK36 expression was upregulated in PCa tissue compared with adjacent benign PCa tissue; it was higher in patients with advanced stages compared with lower stages and was significantly correlated with decreased overall survival. Up-regulation of STK36 significantly promoted the proliferation, invasion, and migration of DU-145 and PC-3 cells and compensated for the suppression caused by docetaxel treatment in vitro. A striking apoptosis inhibition could be observed when dealing with docetaxel, although the apoptosis of DU-145 and PC-3 cells was not affected by the STK36 exclusive overexpression. Besides, E-Cadherin expression was restrained while the expression levels of vimentin were all enhanced. The knockdown of STK36 reversed the above process. STK36 up-regulation could accelerate the biological behavior and docetaxel resistance of PCa by epithelial-mesenchymal transition (EMT) activation. STK36 may be potentially used as a target in PCa resolvent with docetaxel.

DHCR24 in Tumor Diagnosis and Treatment: A Comprehensive Review

As an important nutrient in the human body, cholesterol can not only provide structural components for the body's cells, but also can be transformed into a variety of active substances to regulate cell signaling pathways. As an important cholesterol synthase, DHCR24 participates in important regulatory processes in the body. The application of DHCR24 in tumor clinical diagnosis and treatment also attracts much attention. This article reviews the structure and regulatory characteristics of DHCR24, and the research of DHCR24 on tumor progression. We summarize the possible mechanisms of DHCR24 promoting tumor progression through reactive oxygen species (ROS), p53, Ras and PI3K-AKT pathways. Through our review, we hope to provide more research ideas and reference value for the application of DHCR24 in tumor prevention and treatment.

Comparison of PLLA-PEG and PDLLA-PEG micelles for co-encapsulation of docetaxel and resveratrol

The interest in combining chemosensitizers with cytostatics in cancer therapy is growing, which causes also a need to develop their delivery systems. Example of the combination with beneficial therapeutic effects is docetaxel (Dtx) and resveratrol (Res). Although poly(lactide)-co-poly(ethylene glycol) (PLA-PEG) micelles have been considered as one of the most promising platforms for drug delivery, their properties may depend on the stereoisomeric form of hydrophobic block. Therefore, the aim of this study was evaluation of the effect of PLA block on co-encapsulation and release rate of Dtx and Res, which has not been studied so far. This article presents a comparison of single- (Dtx or Res) and dual-drug (Dtx and Res) loaded micelles obtained from poly(l,l-lactide)-co-poly(ethylene glycol) (PLLA-PEG) and poly(d,l-lactide)-co-poly(ethylene glycol) (PDLLA-PEG). The analyzes of the micelles have been conducted including morphology, drug(s) encapsulation efficiency, intermolecular interactions, in vitro drug release, and cytotoxicity. Differences in drug loading ability and release profile have been observed between Res and Dtx but also depending on the polymer and number of drugs in micelles (single vs. dual loaded). The PLLA-PEG micelles have a significantly higher Dtx encapsulation capacity than PDLLA-PEG micelles. The highest cytotoxicity was shown for Dtx and Res dual-loaded micelles, regardless of the polymer. The findings may be used for selection of PLA-based drug delivery systems containing Dtx and Res.

Caffeic Acid Phenethyl Ester: A Potential Therapeutic Cancer Agent?

BACKGROUND

Propolis and its major phenolic compound, caffeic acid phenethyl ester (CAPE), have garnered considerable scientific interest due to their anti- inflammatory properties and potential therapeutic applications.

OBJECTIVES

This narrative review explores the potential utility of CAPE in cancer treatment.

METHODS

We comprehensively reviewed relevant studies from scientific databases (PubMed and Web of Science) from 2000 to 2022. Our search focused on keywords such as cancer, natural drugs, caffeic acid phenethyl ester, CAPE, cancer cell lines, antitumor effects, and propolis.

RESULTS

CAPE exhibits diverse biological benefits, including antimicrobial, antioxidant, antiviral, anti-inflammatory, cytotoxic, and potentially anti-carcinogenic properties. Numerous studies have demonstrated its wide-ranging antitumor effects on various cancer cell lines, including growth inhibition, apoptosis induction, tumor invasiveness prevention, malignancy suppression, and anti-angiogenic activity.

CONCLUSION

Following comprehensive preclinical toxicity assessments, further evaluation of CAPE's efficacy and safety through clinical trials is highly recommended to elucidate its potential health benefits in diverse forms of human cancer.

Antitumor Effect of Poplar Propolis on Human Cutaneous Squamous Cell Carcinoma A431 Cells

Propolis is a gelatinous substance processed by western worker bees from the resin of plant buds and mixed with the secretions of the maxillary glands and beeswax. Propolis has extensive biological activities and antitumor effects. There have been few reports about the antitumor effect of propolis against human cutaneous squamous cell carcinoma (CSCC) A431 cells and its potential mechanism. CCK-8 assays, label-free proteomics, RT-PCR, and a xenograft tumor model were employed to explore this possibility. The results showed that the inhibition rate of A431 cell proliferation by the ethanol extract of propolis (EEP) was dose-dependent, with an IC50 of 39.17 μg/mL. There were 193 differentially expressed proteins in the EEP group compared with the control group (p < 0.05), of which 103 proteins (53.37%) were upregulated, and 90 proteins (46.63%) were downregulated. The main three activated and suppressed Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were extracellular matrix (ECM)-receptor interaction, amoebiasis, cell adhesion molecules (CAMs), nonalcoholic fatty liver disease (NAFLD), retrograde endocannabinoid signaling, and Alzheimer's disease. The tumor volume of the 100 mg/kg EEP group was significantly different from that of the control group (p < 0.05). These results provide a theoretical basis for the potential treatment of human CSCC A431 cell tumors using propolis.

Inhibiting MEK1 R189 citrullination enhances the chemosensitivity of docetaxel to multiple tumour cells

Drug resistance is still a big challenge for cancer patients. We previously demonstrated that inhibiting peptidylarginine deiminase 2 (PADI2) enzyme activity with Cl-amine increases the efficacy of docetaxel (Doc) on tamoxifen-resistant breast cancer cells with PADI2 expression. However, it is not clear whether this effect applies to other tumour cells. Here, we collected four types of tumour cells with different PADIs expression and fully evaluated the inhibitory effect of the combination of PADIs inhibitor (BB-Cla) and Doc in vitro and in vivo on tumour cell growth. Results show that inhibiting PADIs combined with Doc additively inhibits tumour cell growth across the four tumour cells. PADI2-catalysed citrullination of MEK1 Arg 189 exists in the four tumour cells, and blocking the function of MEK1 Cit189 promotes the anti-tumour effect of Doc in these tumour cells. Further analysis shows that inhibiting MEK1 Cit189 decreases the expression of cancer cell stemness factors and helps prevent cancer cell stemness maintenance. Importantly, this combined treatment can partially restore the sensitivity of chemotherapy-resistant cells to docetaxel or cisplatin in tumour cells. Thus, our study provides an experimental basis for the combined therapeutic approaches using docetaxel- and PADIs inhibitors-based strategies in tumour treatment. This article is part of the Theo Murphy meeting issue 'The virtues and vices of protein citrullination'.

Rational Design of Bioorthogonally Activatable PROTAC for Tumor-Targeted Protein Degradation

Protein degradation mediated by the proteolysis-targeting chimera (PROTAC) has emerged as an efficient strategy to accurately control intracellular protein levels. However, the development of PROTACs is limited by their systemic toxicity. Herein, we report a bioorthogonally activatable prodrug (BT-PROTAC) strategy to accurately control the activity of PROTACs. As a proof of concept, we introduced the highly reactive trans-cyclooctene into PROTAC molecule MZ1, the structure-acitivity relationships of which were well characterized previously, to construct the bioorthogonally activatable prodrug BT-PROTAC. Compared with MZ1, BT-PROTAC is incapable of degradation of BRD4 protein. However, BT-PROTAC can be activated by highly active tetrazine compound BODIPY-TZ in vitro. Furthermore, we could selectively degrade BRD4 protein in tumor tissue enabled by tumor-targeted tetrazine compound IR808-TZ. This strategy may represent an alternative to existing strategies and may be widely applied in the design of BT-PROTAC targeting other proteins.

Transforming growth factor-β and bone morphogenetic protein signaling pathways in pathological cardiac hypertrophy

Pathological cardiac hypertrophy (referred to as cardiac hypertrophy) is a maladaptive response of the heart to a variety of pathological stimuli, and cardiac hypertrophy is an independent risk factor for heart failure and sudden death. Currently, the treatments for cardiac hypertrophy are limited to improving symptoms and have little effect. Elucidation of the developmental process of cardiac hypertrophy at the molecular level and the identification of new targets for the treatment of cardiac hypertrophy are crucial. In this review, we summarize the research on multiple active substances related to the pathogenesis of cardiac hypertrophy and the signaling pathways involved and focus on the role of transforming growth factor-β (TGF-β) and bone morphogenetic protein (BMP) signaling in the development of cardiac hypertrophy and the identification of potential targets for molecular intervention. We aim to identify important signaling molecules with clinical value and hope to help promote the precise treatment of cardiac hypertrophy and thus improve patient outcomes.

Skin cancer: understanding the journey of transformation from conventional to advanced treatment approaches

Skin cancer is a global threat to the healthcare system and is estimated to incline tremendously in the next 20 years, if not diagnosed at an early stage. Even though it is curable at an early stage, novel drug identification, clinical success, and drug resistance is another major challenge. To bridge the gap and bring effective treatment, it is important to understand the etiology of skin carcinoma, the mechanism of cell proliferation, factors affecting cell growth, and the mechanism of drug resistance. The current article focusses on understanding the structural diversity of skin cancers, treatments available till date including phytocompounds, chemotherapy, radiotherapy, photothermal therapy, surgery, combination therapy, molecular targets associated with cancer growth and metastasis, and special emphasis on nanotechnology-based approaches for downregulating the deleterious disease. A detailed analysis with respect to types of nanoparticles and their scope in overcoming multidrug resistance as well as associated clinical trials has been discussed.

Molecular Insight into Prostate Cancer: Preventive Role of Selective Bioactive Molecules

Prostate cancer (CaP) is one of the most prevalent male malignancies, accounting for a considerable number of annual mortalities. However, the prompt identification of early-stage CaP often faces delays due to diverse factors, including socioeconomic inequalities. The androgen receptor (AR), in conjunction with various other signaling pathways, exerts a central influence on the genesis, progression, and metastasis of CaP, with androgen deprivation therapy (ADT) serving as the primary therapeutic strategy. Therapeutic modalities encompassing surgery, chemotherapy, hormonal intervention, and radiotherapy have been formulated for addressing early and metastatic CaP. Nonetheless, the heterogeneous tumor microenvironment frequently triggers the activation of signaling pathways, culminating in the emergence of chemoresistance, an aspect to which cancer stem cells (CSCs) notably contribute. Phytochemicals emerge as reservoirs of bioactive agents conferring manifold advantages against human morbidity. Several of these phytochemicals demonstrate potential chemoprotective and chemosensitizing properties against CaP, with selectivity exhibited towards malignant cells while sparing their normal counterparts. In this context, the present review aims to elucidate the intricate molecular underpinnings associated with metastatic CaP development and the acquisition of chemoresistance. Moreover, the contributions of phytochemicals to ameliorating CaP initiation, progression, and chemoresistance are also discussed.

Androgen receptor knockdown enhances prostate cancer chemosensitivity by down-regulating FEN1 through the ERK/ELK1 signalling pathway

PURPOSE

Flap endonuclease 1 (FEN1) is highly upregulated in prostate cancer and promotes the growth of prostate cancer cells. Androgen receptor (AR) is the most critical determinant of the occurrence, progression, metastasis, and treatment of prostate cancer. However, the effect of FEN1 on docetaxel (DTX) sensitivity and the regulatory mechanisms of AR on FEN1 expression in prostate cancer need to be further studied.

METHODS

Bioinformatics analyses were performed using data from the Cancer Genome Atlas and the Gene Expression Omnibus. Prostate cancer cell lines 22Rv1 and LNCaP were used. FEN1 siRNA, FEN1 overexpression plasmid, and AR siRNA were transfected into cells. Biomarker expression was evaluated by immunohistochemistry and Western blotting. Apoptosis and the cell cycle were explored using flow cytometry analysis. Luciferase reporter assay was performed to verify the target relationship. Xenograft assays were conducted using 22Rv1 cells to evaluate the in vivo conclusions.

RESULTS

Overexpression of FEN1 inhibited cell apoptosis and cell cycle arrest in the S phase induced by DTX. AR knockdown enhanced DTX-induced cell apoptosis and cell cycle arrest at the S phase in prostate cancer cells, which was attenuated by FEN1 overexpression. In vivo experiments showed that overexpression of FEN1 significantly increased tumour growth and weakened the inhibitory effect of DTX on prostate tumour growth, while AR knockdown enhance the sensitivity of DTX to prostate tumour. AR knockdown resulted in FEN1, pho-ERK1/2, and pho-ELK1 downregulation, and the luciferase reporter assay confirmed that ELK1 can regulate the transcription of FEN1.

CONCLUSION

Collectively, our studies demonstrate that AR knockdown improves the DTX sensitivity of prostate cancer cells by downregulating FEN1 through the ERK/ELK1 signalling pathway.

Caffeic acid phenethyl ester suppresses EGFR/FAK/Akt signaling, migration, and tumor growth of prostate cancer cells

BACKGROUND

Epidermal growth factor receptor (EGFR) is upregulated in prostate cancer (PCa). However, suppression of EGFR did not improve the patient outcome, possibly due to the activation of PI3K/Akt signaling in PCa. Compounds able to suppress both PI3K/Akt and EGFR signaling may be effective for treating advanced PCa.

PURPOSE

We examined if caffeic acid phenethyl ester (CAPE) simultaneously suppresses the EGFR and Akt signaling, migration and tumor growth in PCa cells.

METHODS

Wound healing assay, transwell migration assay and xenograft mice model were used to determine the effects of CAPE on migration and proliferation of PCa cells. Western blot, immunoprecipitation, and immunohistochemistry staining were performed to determine the effects of CAPE on EGFR and Akt signaling.

RESULTS

CAPE treatment decreased the gene expression of HRAS, RAF1, AKT2, GSK3A, and EGF and the protein expression of phospho-EGFR (Y845, Y1069, Y1148, Y1173), phospho-FAK, Akt, and ERK1/2 in PCa cells. CAPE treatment inhibited the EGF-induced migration of PCa cells. Combined treatment of CAPE with EGFR inhibitor gefitinib showed additive inhibition on migration and proliferation of PCa cells. Injection of CAPE (15 mg/kg/3 days) for 14 days suppressed the tumor growth of prostate xenografts in nude mice as well as suppressed the levels of Ki67, phospho-EGFR Y845, MMP-9, phospho-Akt S473, phospho-Akt T308, Ras, and Raf-1 in prostate xenografts.

CONCLUSIONS

Our study suggested that CAPE can simultaneously suppress the EGFR and Akt signaling in PCa cells and is a potential therapeutic agent for advanced PCa.

Active Targeting of P-Selectin by Fucoidan Modulates the Molecular Profiling of Metastasis in Docetaxel-Resistant Prostate Cancer

The standard of care for prostate cancer (PCa) is androgen deprivation therapy (ADT). Although hormone-sensitive PCa is curable by ADT, most conditions progress to castration-resistant prostate cancer (CRPCa) and metastatic CRPCa (mCRPCa). Front-line docetaxel has been administered to patients with CRPCa and mCRPCa. Nevertheless, docetaxel resistance after half a year of therapy has emerged as an urgent clinical concern in patients with CRPCa and mCRPCa. We verified the mechanism by which docetaxel-resistant PCa cells (DU/DX50) exhibited significant cell migration and expression of malignant tumor-related proteins. Our study shows that the biological activity of fucoidan has an important application for docetaxel-resistant PCa cells, inhibiting IL-1R by binding to P-selectin and reducing the expression levels of NF-κB p50 and Cox2 in this metastasis-inhibiting signaling pathway. Furthermore, the combined treatment of fucoidan and docetaxel showed significant anticancer and synergistic effects on the viability of DU/DX50 cells, which is relevant for overcoming the current limitations and improving treatment outcomes. Overall, fucoidan-based combination chemotherapy may exert beneficial effects and facilitate the treatment of docetaxel-resistant PCa.

An Insight into Anticancer Effect of Propolis and Its Constituents: A Review of Molecular Mechanisms

Propolis is a natural compound collected by honeybees from different parts of plants. Honeybees produce a sticky component besides honey by mixing the tree resin and other botanical sources with saliva called propolis or bee glue. Propolis was traditionally used as a wound healing substance, cosmetic, medicine, and many other conditions. Till now, there is no definite curable treatment for most cancers and chemotherapeutic drugs and drugs used for targeted therapies have serious side effects. According to a recent research, natural products are becoming increasingly essential in cancer prevention. Natural products are a great source of potential therapeutic agents, especially in the treatment of cancer. Previous studies have reported that the presence of caffeic acid phenethyl ester (CAPE), artepillin C, and chrysin is responsible for the anticancer potential of propolis. Most of the previous studies suggested that propolis and its active compounds inhibit cancer progression by targeting multiple signaling pathways including phosphoinositide 3-kinases (PI3K)/Akt and mitogen-activated protein kinase (MAPK) signaling molecules, and induce cell cycle arrest. Induction of apoptosis by propolis is mediated through extrinsic and intrinsic apoptotic pathways. The aim of this review is to highlight and summarize the molecular targets and anticancer potential of propolis and its active compounds on cell survival, proliferation, metastasis, and apoptosis in cancer cells.