miR-31 shuttled by halofuginone-induced exosomes suppresses MFC-7 cell proliferation by modulating the HDAC2/cell cycle signaling axis

New uses of halofuginone to treat cancer

The small-molecule alkaloid halofuginone (HF) is obtained from febrifugine. Recent studies on HF have aroused widespread attention owing to its universal range of noteworthy biological activities and therapeutic functions, which range from parasite infections and fibrosis to autoimmune diseases. In particular, HF is believed to play an excellent anticancer role by suppressing the proliferation, adhesion, metastasis, and invasion of cancers. This review supports the goal of demonstrating various anticancer effects and molecular mechanisms of HF. In the studies covered in this review, the anticancer molecular mechanisms of HF mainly included transforming growth factor-β (TGF-β)/Smad-3/nuclear factor erythroid 2-related factor 2 (Nrf2), serine/threonine kinase proteins (Akt)/mechanistic target of rapamycin complex 1(mTORC1)/wingless/integrated (Wnt)/β-catenin, the exosomal microRNA-31 (miR-31)/histone deacetylase 2 (HDAC2) signaling pathway, and the interaction of the extracellular matrix (ECM) and immune cells. Notably, HF, as a novel type of adenosine triphosphate (ATP)-dependent inhibitor that is often combined with prolyl transfer RNA synthetase (ProRS) and amino acid starvation therapy (AAS) to suppress the formation of ribosome, further exerts a significant effect on the tumor microenvironment (TME). Additionally, the combination of HF with other drugs or therapies obtained universal attention. Our results showed that HF has significant potential for clinical cancer treatment.

Experimental study on the inhibitory effect of Halofuginone on NSCLC

In recent decades, significant advancements have been achieved in non-small cell lung cancer (NSCLC) treatment. However, drug resistance, postoperative recurrence, distant metastasis, and other critical issues arise during NSCLC treatment. Natural products play a crucial role in the development of anti-tumor drugs. Halofuginone (HF) is a derivative of Febrifugine, an extract of Dichroa febrifuga Lour, a traditional Chinese medicine. Recent studies on HF have demonstrated its antitumor activity and great potential for clinical applications. However, its antitumor effects and mechanisms in NSCLC remain unknown. This study aimed to elucidate the antitumor effect of HF on NSCLC and preliminarily explore its mechanism of action. The proliferation-related assay revealed that HF could inhibit the proliferation of lung adenocarcinoma cells HCC827 and H1975. Network pharmacology of HF and NSCLC indicated that HF could induce cellular oxidative stress, and the antitumor effect was related to autophagy, apoptosis, and cell cycle arrest. Experimental analysis using flow cytometry and western blotting confirmed that HF indeed induced autophagy, enhanced apoptosis, and caused cell cycle arrest. The addition of N-acetyl-cysteamine acid inhibits the HF-induced increase in reactive oxygen species levels, inhibits autophagy and apoptosis, and alters cell cycle distribution. The HCC827 transplantation tumor animal model established that HF substantially inhibited the growth of transplanted tumors. These findings suggest that HF exerts a significant inhibitory effect on NSCLC in vivo and in vitro. The inhibitory effect of HF on NSCLC was associated with the increase of ROS in tumor cells, induction of autophagy and apoptosis, and cell cycle arrest.

Halofuginone prevents inflammation and proliferation of high-altitude pulmonary hypertension by inhibiting the TGF-β1/Smad signaling pathway

The inflammatory response of lung tissue and abnormal proliferation of pulmonary artery smooth muscle cells are involved in the pathogenesis of high-altitude pulmonary hypertension (HAPH). Halofuginone (HF), an active ingredient derivative of Chang Shan (Dichroa febrifuga Lour. [Hydrangeaceae]), has antiproliferative, antihypertrophic, antifibrotic, and other effects, but its protective effects on HAPH remains unclear. In the present study, we evaluated the efficacy of HF on HAPH by establishing a 6000 m HAPH rat model. Male Sprague-Dawley rats were divided into normoxia, normoxia + halofuginone (1 mg/kg), hypoxia, and hypoxia + halofuginone (1 mg/kg) groups. The results showed that HF (1 mg/kg) could prevent hypoxia-induced hemodynamic abnormalities, right ventricular hypertrophy, and pulmonary vascular remodeling in rats. We further detected the expression levels of inflammatory factors interleukin (IL)-1β, IL-6, tumor necrosis factor-α (TNF-α) and proliferative/antiproliferative indicators proliferating cell nuclear antigen (PCNA), cyclin-dependent kinase 6 (CDK6), Cyclin D1, p21 in lung tissue, and found that HF could attenuate the lung tissue inflammatory response and proliferative response in HAPH rats. In addition, we also examined the expression levels of transforming growth factor-β1 (TGF-β1), Smad2/3 and p-Smad2/3 in lung tissue, and found that HF exerted therapeutic effects by inhibiting the TGF-β1/Smad signaling pathway.

Injectable nano-in situ-thermosensitive-hydrogels based on halofuginone and silver for postoperative treatment against triple-negative breast cancer

Postoperative distant metastasis and high recurrence rate causes a dilemma in treating triple-negative breast cancer (TNBC) owing to its unforeseeable invasion into various organs or tissues. The wealth of nutrition provided by vascular may facilitate the proliferation and angiogenesis of cancer cells, which further enhance the rates of postoperative metastasis and recurrence. Chemotherapy, as a systemic postoperative adjuvant therapy, is generally applied to diminish recurrence and metastasis of TNBC. Herein, an halofuginone-silver nano thermosensitive hydrogel (HTPM&AgNPs-gel) was prepared via a physical swelling method. The in vitro anticancer efficacy of HTPM&AgNPs-gel was analyzed by investigating cell proliferation, migration, invasion, and angiogenesis capacity. Furthermore, the in vivo anti-cancer activity of HTPM&AgNPs-gel was further appraised through the tumor suppression, anti-metastatic, anti-angiogenic, and anti-inflammatory ability. The optimized HTPM&AgNPs-gel, a thermosensitive hydrogel, showed excellent properties, including syringeability, swelling behavior, and a sustained release effect without hemolysis. In addition, HTPM&AgNPs-gel was confirmed to effectively inhibit the proliferation, migration, invasion, and angiogenesis of MDA-MB-231 cells. An evaluation of the in vivo anti-tumor efficacy demonstrated that HTPM&AgNPs-gel showed a stronger tumor inhibition rate (68.17%) than did HTPM-gel or AgNPs-gel used alone and exhibited outstanding biocompatibility. Notably, HTPM&AgNPs-gel also inhibited lung metastasis induced by residual tumor tissue after surgery and further blocked angiogenesis-related inflammatory responses. Taken together, the suppression of inflammation by interdicting the blood vessels adjoining the tumor and inhibiting angiogenesis is a potential strategy to attenuate the recurrence and metastasis of TNBC. HTPM&AgNPs-gel is a promising anticancer agent for TNBC as a local postoperative treatment.

Dipsacus Asperoides-Derived Exosomes-Like Nanoparticles Inhibit the Progression of Osteosarcoma via Activating P38/JNK Signaling Pathway

INTRODUCTION

Osteosarcoma is a prevalent and highly malignant primary bone tumor. However, current clinical therapeutic drugs for osteosarcoma are not suitable for long-term use due to significant side effects. Therefore, there is an urgent need to develop new drugs with fewer side effects. Dipsacus asperoides C. Y. Cheng et T. M. Ai, a traditional Chinese medicine, is commonly used for its anti-inflammatory, anti-pain, bone fracture healing, and anti-tumor effects. In this study, we investigated the effects of exosome-like nanoparticles derived from Dipsacus asperoides (DAELNs) on osteosarcoma cells in vitro and in vivo.

METHODS

DAELNs were isolated and purified from Dipsacus asperoides and their physical and chemical properties were characterized using transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). The cellular uptake of DAELNs in osteosarcoma cells was analyzed by PKH26 staining. The proliferation, invasion, migration, and apoptosis of osteosarcoma cells were assessed using CCK8 assay, EdU assay, colony-formation assay, transwell assay, wound healing assay, and mitochondrial membrane potential measurement, respectively. The regulatory mechanism of DAELNs inhibiting the progression of osteosarcoma via activating P38/JNK signaling pathway was investigated using Western blotting and immunohistochemistry. Moreover, the therapeutic effects of DAELNs were evaluated using in vivo small animal imaging assay, HE staining, and immunohistochemistry.

RESULTS

Our results showed that DAELNs inhibited the proliferation, invasion, migration, and fostered the apoptosis of osteosarcoma cells in vitro and suppressed the tumor growth of osteosarcoma cells in a xenograft nude mouse model. Furthermore, the bio-distribution of DiD-labeled DAELNs showed preferential targeting of osteosarcoma tumors and excellent biosafety in histological analysis of the liver and kidney. Mechanistically, DAELNs activated the P38/JNK signaling pathway-induced apoptosis.

CONCLUSION

Taken together, DAELNs are novel, natural, and osteosarcoma-targeted agents that can serve as safe and effective therapeutic approaches for the treatment of osteosarcoma.

SSPH I, A Novel Anti-cancer Saponin, Inhibits EMT and Invasion and Migration of NSCLC by Suppressing MAPK/ERK1/2 and PI3K/AKT/ mTOR Signaling Pathways

BACKGROUND

Saponin of Schizocapsa plantaginea Hance I (SSPH I).a bioactive saponin found in Schizocapsa plantaginea, exhibits significant anti-proliferation and antimetastasis in lung cancer.

OBJECTIVE

To explore the anti-metastatic effects of SSPH I on non-small cell lung cancer (NSCLC) with emphasis on epithelial-mesenchymal transition (EMT) both in vitro and in vivo.

METHODS

The effects of SSPH I at the concentrations of 0, 0.875,1.75, and 3.5 μM on A549 and PC9 lung cancer cells were evaluated using colony formation assay, CCK-8 assay, transwell assay and wound-healing assay. The actin cytoskeleton reorganization of PC9 and A549 cells was detected using the FITC-phalloidin fluorescence staining assay. The proteins related to EMT (N-cadherin, E-cadherin and vimentin), p- PI3K, p- AKT, p- mTOR and p- ERK1/2 were detected by Western blotting. A mouse model of lung cancer metastasis was established by utilizing 95-D cells, and the mice were treated with SSPH I by gavage.

RESULTS

The results suggested that SSPH I significantly inhibited the migration and invasion of NSCLC cells under a non-cytotoxic concentration. Furthermore, SSPH I at a non-toxic concentration of 0.875 μM inhibited F-actin cytoskeleton organization. Importantly, attenuation of EMT was observed in A549 cells with upregulation in the expression of epithelial cell marker E-cadherin and downregulation of the mesenchymal cell markers vimentin as well as Ncadherin. Mechanistic studies revealed that SSPH I inhibited MAPK/ERK1/2 and PI3K/AKT/mTOR signaling pathways.

CONCLUSION

SSPH I inhibited EMT, migration, and invasion of NSCLC cells by suppressing MAPK/ERK1/2 and PI3K/AKT/mTOR signaling pathways, suggesting that the natural compound SSPH I could be used for inhibiting metastasis of NSCLC.

Erxian Decoction-induced serum exosomes slowed bone marrow mesenchymal stem cell senescence through mitophagy

OBJECTIVE

Erxian Decoction (EXD) is traditionally employed in the treatment of menopausal syndromes, although its underlying mechanisms remain largely undefined. Given that the senescence of bone marrow mesenchymal stem cells (BMSCs) is intertwined with organismal aging and associated diseases, this study endeavored to elucidate the influence of EXD on aging BMSCs and uncover the mechanisms through which EXD impedes BMSC senescence.

METHODS

Initially, we probed the anti-senescent mechanisms of EXD on BMSCs via network pharmacology. We subsequently isolated and identified exosomes from the serum of EXD-fed rats (EXD-Exos) and administered these to H2 O2 -induced aging BMSC. Assays were conducted to assess BMSC senescence indicators and markers pertinent to mitochondrial autophagy. Treatments with mitophagy inhibitors and activators were then employed to substantiate our findings.

RESULTS

Protein-protein interaction (PPI) network analyses spotlighted AKT1, TP53, TNF, JUN, VEGFA, IL6, CASP3 and EGFR as focal targets. Gene Ontology and Kyoto Encylcopedia of Genes and Genomes pathway analyses underscored oxidative stress, mitophagy and cell proliferation as pivotal processes. Our cellular assays ascertained that EXD-Exos mitigated H2 O2 -induced senescence phenotypes in BMSCs. Moreover, EXD-Exos ameliorated disrupted mitophagy in BMSCs, as evidenced by enhanced cellular membrane potential and diminished reactive oxygen species levels. Intriguingly, EXD-Exos also preserved the osteogenic differentiation potential of BMSCs while curtailing their adipogenic propensity.

CONCLUSION

Our findings compellingly suggest that EXD counteracts BMSC senescence by fostering mitophagy.

Potential targets of natural medicines: preventing lung cancer pre-metastatic niche formation by regulating exosomes

Lung cancer is one of the most devastating diseases worldwide with high incidence and mortality, and the incidence continues to rise. Metastasis is the leading cause of death in lung cancer patients, yet the molecular effectors underlying tumor dissemination remain poorly defined. Research findings in recent years confirmed primed microenvironment of future metastatic sites, called the pre-metastatic niche, is a prerequisite for overt metastasis. Exosomes have recently emerged as important players in pre-metastatic niche formation. Natural medicines have traditionally been rich sources of drug discovery. Some of them exhibit favorable anti-lung cancer activity. The review focused on the latest advances in the regulation of the pre-metastatic niche formation in lung cancer by the contents of exosomes of representative natural medicines. Additionally, the mechanism of natural medicines was summarized in detail, which would provide new insights for anti-cancer new drug development.

Targeting tumor-derived exosome-mediated premetastatic niche formation: The metastasis-preventive value of traditional Chinese medicine

Tumor-derived exosome (TDE)-mediated premetastatic niche (PMN) formation is a potential mechanism underlying the organotropic metastasis of primary tumors. Traditional Chinese medicine (TCM) has shown considerable success in preventing and treating tumor metastasis. However, the underlying mechanisms remain elusive. In this review, we discussed PMN formation from the perspectives of TDE biogenesis, cargo sorting, and TDE recipient cell alterations, which are critical for metastatic outgrowth. We also reviewed the metastasis-preventive effects of TCM, which act by targeting the physicochemical materials and functional mediators of TDE biogenesis, regulating the cargo sorting machinery and secretory molecules in TDEs, and targeting the TDE-recipient cells involved in PMN formation.

Design, Synthesis and Antitumor Activity of FAK/PLK1 Dual Inhibitors with Quinazolinone as the Skeleton

Febrifugine is a kind of quinazolinone compound with high biological activity from a Chinese herb called Chang Shan (Dichroa febrifuga). Febrifugine and its derivatives possess extensive biological activities, some of which exhibited anti-tumor activities as FAK inhibitors. However, they are not very effective at inhibiting tumor metastasis, perhaps because tumors gain energy through compensatory activation of other signaling pathways that promote cell migration and invasion. Therefore, seventeen novel febrifugine derivatives with quinazolinone skeleton were designed, synthesized and acted as potential FAK/PLK1 dual inhibitors. These compounds were determined by ¹ H-NMR, ¹³ C-NMR and MS. Most of the compounds exhibited good inhibitory activity against cancer cell lines by computer-assisted screening, antitumor activity test and FAK/PLK1 inhibitory activity test, wherein compound 3b was screened as a high-efficiency lead compound.

Exosomes: A novel insight into traditional Chinese medicine

Exosomes are small extracellular vesicles and play an essential role in the mediation of intercellular communication both in health and disease. Traditional Chinese medicine (TCM) has historically been used to maintain human health and treat various diseases up till today. The interplay between exosomes and TCM has attracted researchers’ growing attention. By integrating the available evidence, TCM formulas and compounds isolated from TCM as exosome modulators have beneficial effects on multiple disorders, such as tumors, kidney diseases, and hepatic disease, which may associate with inhibiting cells proliferation, anti-inflammation, anti-oxidation, and attenuating fibrosis. Exosomes, a natural delivery system, are essential in delivering compounds isolated from TCM to target cells or tissues. Moreover, exosomes may be the potential biomarkers for TCM syndromes, providing strategies for TCM treatment. These findings may provide a novel insight into TCM from exosomes and serve as evidence for better understanding and development of TCM.

Orally Administered Halofuginone-Loaded TPGS Polymeric Micelles Against Triple-Negative Breast Cancer: Enhanced Absorption and Efficacy with Reduced Toxicity and Metastasis

Background

Halofuginone (HF)-loaded TPGS polymeric micelles (HTPM) were successfully fabricated using the thin-film hydration technique. HTPM via intravenous injection have been demonstrated to exert an excellent anticancer effect against triple-negative breast cancer (TNBC) cells and subcutaneous xenografts. In the present study, we further explored the potential treatment effect and mechanism of orally administered HTPM alone and in combination with surgical therapy on TNBC in subcutaneous and orthotopic mouse models.

Methods

Herein, the stability and in vitro release behavior of HTPM were first evaluated in the simulated gastrointestinal fluids. Caco-2 cell monolayers were then used to investigate the absorption and transport patterns of HF with/without encapsulation in TPGS polymeric micelles. Subsequently, the therapeutic effect of orally administered HTPM was checked on subcutaneous xenografts of TNBC in nude mice. Ultimately, orally administered HTPM, combined with surgical therapy, were utilized to treat orthotopic TNBC in nude mice.

Results

Our data confirmed that HTPM exhibited good stability and sustained release in the simulated gastrointestinal fluids. HF was authenticated to be a substrate of P-glycoprotein (P-gp), and its permeability across Caco-2 cell monolayers was markedly enhanced via heightening intracellular absorption and inhibiting P-gp efflux due to encapsulation in TPGS polymeric micelles. Compared with HF alone, HTPM showed stronger tumor-suppressing effects in subcutaneous xenografts of MDA-MB-231 cells when orally administered. Moreover, compared with HTPM or surgical therapy alone, peroral HTPM combined with partial surgical excision synergistically retarded the growth of orthotopic TNBC. Fundamentally, HTPM orally administered at the therapeutic dose did not cause any pathological injury, while HF alone led to weight loss and jejunal bleeding in the investigated mice.

Conclusion

Taken together, HTPM could be applied as a potential anticancer agent for TNBC by oral administration.

Shikonin inhibited glycolysis and sensitized cisplatin treatment in non-small cell lung cancer cells via the exosomal pyruvate kinase M2 pathway

The active ingredient of the traditional Chinese medicine comfrey is shikonin, a naphthoquinone compound. The focus of this study was to investigate the effect of shikonin on the proliferation, invasion, migration, and chemoresistance of non-small cell lung cancer (NSCLC) cells, and to explore its underlying molecular biological mechanisms. The results show that shikonin inhibited the viability, proliferation, invasion, and migration of NSCLC cells A549 and PC9, and induced apoptosis. As the inhibitor of pyruvate kinase M2 (PKM2), a key enzyme in glycolysis, shikonin inhibited glucose uptake and the production of lactate, the final metabolite of aerobic glycolysis. In vivo chemotherapeutic assay showed that shikonin reduced the tumor volume and weight in NSCLC mice model and increased the sensitivity to cisplatin chemotherapy. Histoimmunology experiments showed the combination of shikonin and cisplatin downregulated the expression of PKM2 and its transcriptionally regulated downstream gene glucose transporter 1 (Glut1) in tumor tissue. In an assessment of glucose metabolism, micro-PET/CT data showed a combination of shikonin and cisplatin inhibited the fluorodeoxy glucose (¹⁸F-FDG) uptake into tumor. Since exosomal PKM2 affected the sensitivity to cisplatin in NSCLC cells, we also demonstrated shikonin could inhibit exosome secretion and exosomal PKM2 through the administration of exosomal inhibitor GW4869. Furthermore, shikonin sensitized cisplatin treatment by reducing the extracellular secretion of exosomal PKM2. In conclusion, we suggest that shikonin not only inhibits PKM2 intracellularly but also reduces glycolytic flux and increases cisplatin sensitivity through the exosomal pathway.

MicroRNAs Are Key Molecules Involved in the Gene Regulation Network of Colorectal Cancer

Colorectal cancer (CRC) is one of the most common types of cancer and one of the leading causes of mortality worldwide. MicroRNAs (miRNAs) play central roles in normal cell maintenance, development, and other physiological processes. Growing evidence has illustrated that dysregulated miRNAs can participate in the initiation, progression, metastasis, and therapeutic resistance that confer miRNAs to serve as clinical biomarkers and therapeutic targets for CRC. Through binding to the 3′-untranslated region (3′-UTR) of target genes, miRNAs can lead to target mRNA degradation or inhibition at a post-transcriptional level. During the last decade, studies have found numerous miRNAs and their potential targets, but the complex network of miRNA/Targets in CRC remains unclear. In this review, we sought to summarize the complicated roles of the miRNA-target regulation network (Wnt, TGF-β, PI3K-AKT, MAPK, and EMT related pathways) in CRC with up-to-date, high-quality published data. In particular, we aimed to discuss the downstream miRNAs of specific pathways. We hope these data can be a potent supplement for the canonical miRNA-target regulation network.

Regulating the production and biological function of small extracellular vesicles: current strategies, applications and prospects

Numerous studies have confirmed the great application potentials of small extracellular vesicles (sEVs) in biological medical field, especially in tissue repair and regeneration. However, the production capability of sEVs by noncancerous cells is very limited, while their dosage requirements in disease treatments are usually very high. Meanwhile, as cell aging, the sEV production capability of cells decreases and the biological function of sEVs changes accordingly. In addition, for special applications, sEVs carrying desired bioactive substances should be designed to perform their expected biological function. Therefore, improving the production of sEVs and precisely regulating their biological function are of great significance for promoting the clinical applications of sEVs. In this review, some of the current classic strategies in affecting the cellular behaviors of donor cells and subsequently regulating the production and biological function of their sEVs are summarized, including gene engineering methods, stress-inducing conditions, chemical regulators, physical methods, and biomaterial stimulations. Through applying these strategies, increased yield of sEVs with required biological function can be obtained for disease treatment and tissue repair, such as bone regeneration, wound healing, nerve function recovery and cancer treatment, which could not only reduce the harvest cost of sEV but promote the practical applications of sEVs in clinic.

Tumor-Derived Exosomal Non-Coding RNAs: The Emerging Mechanisms and Potential Clinical Applications in Breast Cancer

Breast cancer (BC) is the most frequent malignancy and is ranking the leading cause of cancer-related death among women worldwide. At present, BC is still an intricate challenge confronted with high invasion, metastasis, drug resistance, and recurrence rate. Exosomes are membrane-enclosed extracellular vesicles with the lipid bilayer and recently have been confirmed as significant mediators of tumor cells to communicate with surrounding cells in the tumor microenvironment. As very important orchestrators, non-coding RNAs (ncRNAs) are aberrantly expressed and participate in regulating gene expression in multiple human cancers, while the most reported ncRNAs within exosomes in BC are microRNAs (miRNAs), long-noncoding RNAs (lncRNAs), and circular RNAs (circRNAs). Notably, ncRNAs containing exosomes are novel frontiers to shape malignant behaviors in recipient BC cells such as angiogenesis, immunoregulation, proliferation, and migration. It means that tumor-derived ncRNAs-containing exosomes are pluripotent carriers with intriguing and elaborate roles in BC progression via complex mechanisms. The ncRNAs in exosomes are usually excavated based on specific de-regulated expression verified by RNA sequencing, bioinformatic analyses, and PCR experiments. Here, this article will elucidate the recent existing research on the functions and mechanisms of tumor-derived exosomal miRNA, lncRNA, circRNA in BC, especially in BC cell proliferation, metastasis, immunoregulation, and drug resistance. Moreover, these tumor-derived exosomal ncRNAs that existed in blood samples are proved to be excellent diagnostic biomarkers for improving diagnosis and prognosis. The in-depth understanding of tumor-derived exosomal ncRNAs in BC will provide further insights for elucidating the BC oncogenesis and progress and exploring novel therapeutic strategies for combating BC.

Inhibition of the NRF2/KEAP1 Axis: A Promising Therapeutic Strategy to Alter Redox Balance of Cancer Cells

Significance: The nuclear factor erythroid 2-related factor 2/Kelch-like ECH-associated protein 1 (NRF2/KEAP1) pathway is a crucial and highly conserved defensive system that is required to maintain or restore the intracellular homeostasis in response to oxidative, electrophilic, and other types of stress conditions. The tight control of NRF2 function is maintained by a complex network of biological interactions between positive and negative regulators that ultimately ensure context-specific activation, culminating in the NRF2-driven transcription of cytoprotective genes. Recent Advances: Recent studies indicate that deregulated NRF2 activation is a frequent event in malignant tumors, wherein it is associated with metabolic reprogramming, increased antioxidant capacity, chemoresistance, and poor clinical outcome. On the other hand, the growing interest in the modulation of the cancer cells' redox balance identified NRF2 as an ideal therapeutic target. Critical Issues: For this reason, many efforts have been made to identify potent and selective NRF2 inhibitors that might be used as single agents or adjuvants of anticancer drugs with redox disrupting properties. Despite the lack of specific NRF2 inhibitors still represents a major clinical hurdle, the researchers have exploited alternative strategies to disrupt NRF2 signaling at different levels of its biological activation. Future Directions: Given its dualistic role in tumor initiation and progression, the identification of the appropriate biological context of NRF2 activation and the specific clinicopathological features of patients cohorts wherein its inactivation is expected to have clinical benefits, will represent a major goal in the field of cancer research. In this review, we will briefly describe the structure and function of the NRF2/ KEAP1 system and some of the most promising NRF2 inhibitors, with a particular emphasis on natural compounds and drug repurposing. Antioxid. Redox Signal. 34, 1428-1483.

Halofuginone inhibits tumorigenic progression of 5-FU-resistant human colorectal cancer HCT-15/FU cells by targeting miR-132-3p in vitro

5-Fluorouracil (5-FU)-based chemotherapy is the first-line option for patients with advanced colorectal cancer (CRC). However, the development of chemoresistance is the primary cause of treatment failure. Halofuginone (HF), a small molecule alkaloid derived from febrifugine, has been demonstrated to exert strong anti-proliferative effects. However, to the best of our knowledge, whether HF inhibits the progression of 5-FU-resistant human CRC HCT-15/FU cells, and the underlying mechanisms, remain unknown. In the present study, the effects of HF on HCT-15/FU cells were assessed in vitro. The results revealed that HF inhibited HCT-15/FU cell viability as demonstrated by the MTT and colony formation assays. Following treatment of HCT-15/FU cells with HF, the migratory and invasive capacities of the cells were significantly decreased. MicroRNA (miRNA/miR)-sequencing data, subsequent miRNA trend analysis and reverse transcription-quantitative PCR all demonstrated that miR-132-3p expression was increased following treatment with HF in a dose-dependent manner. Western blot analysis indicated that following treatment with HF, the expression levels of proteins associated with proliferation, invasion and metastasis in cells were markedly downregulated. These results suggested that HF inhibited the proliferation, invasion and migration of HCT-15/FU cells by upregulating the expression levels of miR-132-3p. Therefore, miR-132-3p may serve as a molecular marker, which may be used to predict CRC resistance to 5-FU, and HF may serve as a novel clinical treatment for 5-FU-resistant CRC.

SSPH I, a Novel Anti-Cancer Saponin, Inhibits Autophagy and Induces Apoptosis via ROS Accumulation and ERK1/2 Signaling Pathway in Hepatocellular Carcinoma Cells

Introduction

Saponin of Schizocapsa plantaginea Hance I (SSPH I), a novel bioactive phytochemical isolated from the rhizomes of Schizocapsa plantaginea, has been demonstrated to exhibit anti-cancer activity against various tumors in preclinical studies. However, the molecular mechanisms involved in the suppression of hepatocellular carcinoma (HCC) are poorly understood. The present study aimed at analyzing the effects of SSPH I on autophagy and apoptosis in vitro.

Methods

MTT and colony forming assays were used to detect cell viability and cell proliferation. Hoechst 33,258 staining and flow cytometry were used to determine apoptosis and ROS production. The apoptosis and autophagy-related protein expression levels were evaluated via Western blot assay. Characteristics of autophagy and apoptosis were observed by transmission electron microscopy. Lysosomal activity was stained with Lyso-Tracker Red and Magic Red Cathepsin B.

Results

The results showed that SSPH I exhibited potent anti-cancer activity and proliferation in HepG2 and BEL-7402 cells and inhibited HepG2 cells through inhibiting autophagy and promoting apoptosis. The mechanistic study indicated that the inhibition of autophagy of SSPH I was mediated by blocking autophagosome–lysosome fusion. Additionally, we found that SSPH I could mediate the activation of MAPK/ERK1/2 signaling pathway, and the use of NAC (ROS inhibitor) and U0126 (MEK1/2 inhibitor) converted the effect of SSPH I on apoptosis and autophagy in HepG2 cells.

Conclusion

These data suggest that SSPH I induces tumor cells apoptosis and reduces autophagy in vitro by inducing ROS and activating MAPK/ERK1/2 signaling pathway, indicating that SSPH I might be a novel agent for the treatment of HCC.

Proline Metabolism in Tumor Growth and Metastatic Progression

Cancer cells show a formidable capacity to survive under stringent conditions, to elude mechanisms of control, such as apoptosis, and to resist therapy. Cancer cells reprogram their metabolism to support uncontrolled proliferation and metastatic progression. Phenotypic and functional heterogeneity are hallmarks of cancer cells, which endow them with aggressiveness, metastatic capacity, and resistance to therapy. This heterogeneity is regulated by a variety of intrinsic and extrinsic stimuli including those from the tumor microenvironment. Increasing evidence points to a key role for the metabolism of non-essential amino acids in this complex scenario. Here we discuss the impact of proline metabolism in cancer development and progression, with particular emphasis on the enzymes involved in proline synthesis and catabolism, which are linked to pathways of energy, redox, and anaplerosis. In particular, we emphasize how proline availability influences collagen synthesis and maturation and the acquisition of cancer cell plasticity and heterogeneity. Specifically, we propose a model whereby proline availability generates a cycle based on collagen synthesis and degradation, which, in turn, influences the epigenetic landscape and tumor heterogeneity. Therapeutic strategies targeting this metabolic-epigenetic axis hold great promise for the treatment of metastatic cancers.

Potential Applications of NRF2 Modulators in Cancer Therapy

The nuclear factor erythroid 2-related factor 2 (NRF2)-Kelch-like ECH-associated protein 1 (KEAP1) regulatory pathway plays an essential role in protecting cells and tissues from oxidative, electrophilic, and xenobiotic stress. By controlling the transactivation of over 500 cytoprotective genes, the NRF2 transcription factor has been implicated in the physiopathology of several human diseases, including cancer. In this respect, accumulating evidence indicates that NRF2 can act as a double-edged sword, being able to mediate tumor suppressive or pro-oncogenic functions, depending on the specific biological context of its activation. Thus, a better understanding of the mechanisms that control NRF2 functions and the most appropriate context of its activation is a prerequisite for the development of effective therapeutic strategies based on NRF2 modulation. In line of principle, the controlled activation of NRF2 might reduce the risk of cancer initiation and development in normal cells by scavenging reactive-oxygen species (ROS) and by preventing genomic instability through decreased DNA damage. In contrast however, already transformed cells with constitutive or prolonged activation of NRF2 signaling might represent a major clinical hurdle and exhibit an aggressive phenotype characterized by therapy resistance and unfavorable prognosis, requiring the use of NRF2 inhibitors. In this review, we will focus on the dual roles of the NRF2-KEAP1 pathway in cancer promotion and inhibition, describing the mechanisms of its activation and potential therapeutic strategies based on the use of context-specific modulation of NRF2.

Identification of miRNA-Based Signature as a Novel Potential Prognostic Biomarker in Patients with Breast Cancer

To identify the novel, noninvasive biomarkers to assess the outcome and prognosis of breast cancer (BC), patients with high sensitivity and specificity are greatly desired. Herein, the miRNA expression profile and matched clinical features of BC patients were extracted from The Cancer Genome Atlas (TCGA) database. The preliminary candidates were screened out by the univariate Cox regression test. Then, with the help of LASSO Cox regression analysis, the hsa-let-7b, hsa-mir-101-2, hsa-mir-135a-2, hsa-mir-22, hsa-mir-30a, hsa-mir-31, hsa-mir-3130-1, hsa-mir-320b-1, hsa-mir-3678, hsa-mir-4662a, hsa-mir-4772, hsa-mir-493, hsa-mir-556, hsa-mir-652, hsa-mir-6733, hsa-mir-874, and hsa-mir-9-3 were selected to construct the overall survival (OS) predicting signature, while the hsa-mir-130a, hsa-mir-204, hsa-mir-217, hsa-mir-223, hsa-mir-24-2, hsa-mir-29b-1, hsa-mir-363, hsa-mir-5001, hsa-mir-514a-1, hsa-mir-624, hsa-mir-639, hsa-mir-659, and hsa-mir-6892 were adopted to establish the recurrence-free survival (RFS) predicting signature. Referring to the median risk scores generated by the OS and RFS formulas, respectively, subgroup patients with high risk were strongly related to a poor OS and RFS revealed by Kaplan-Meier (K-M) plots. Meanwhile, receiver operating curve (ROC) analysis validated the accuracy and stability of these two signatures. When stratified by clinical features, such as tumor stage, age, and molecular subtypes, we found that the miRNA-based OS and RFS classifiers were still significant in predicting OS/RFS and showed the best predictive values than any other features. Besides, functional prediction analyses showed that these targeted genes of the enrolled miRNAs were enriched in cancer-associated pathways, such as MAPK/RTK, Ras, and PI3K-Akt signaling pathways. In summary, our observations demonstrate that the novel miRNA-based OS and RFS signatures are independent prognostic indicators for BC patients and worthy to be validated by further prospective studies.

HDAC2-dependent miRNA signature in acute myeloid leukemia

Acute myeloid leukemia (AML) arises from a complex sequence of biological and finely orchestrated events that are still poorly understood. Increasingly, epigenetic studies are providing exciting findings that may be exploited in promising and personalized cutting‐edge therapies. A more appropriate and broader screening of possible players in cancer could identify a master molecular mechanism in AML. Here, we build on our previously published study by evaluating a histone deacetylase (HDAC)2‐mediated miRNA regulatory network in U937 leukemic cells. Following a comparative miRNA profiling analysis in genetically and enzymatically HDAC2‐downregulated AML cells, we identified miR‐96‐5p and miR‐92a‐3p as potential regulators in AML etiopathology by targeting defined genes. Our findings support the potentially beneficial role of alternative physiopathological interventions.