Phosphorylation of cofilin-1 by ERK confers HDAC inhibitor resistance in hepatocellular carcinoma cells via decreased ROS-mediated mitochondria injury

A glimpse into cofilin-1 role in cancer therapy: A potential target to improve clinical outcomes?

Cofilin-1 (CFL1) modulates dynamic actin networks by severing and enhancing depolymerization. The upregulation of cofilin-1 expression in several cancer types is associated with tumor progression and metastasis. However, recent discoveries indicated relevant cofilin-1 functions under oxidative stress conditions, interplaying with mitochondrial dynamics, and apoptosis networks. In this scenario, these emerging roles might impact the response to clinical therapy and could be used to enhance treatment efficacy. Here, we highlight new perspectives of cofilin-1 in the therapy resistance context and discussed how cofilin-1 is involved in these events, exploring aspects of its contribution to therapeutic resistance. We also provide an analysis of CFL1 expression in several tumors predicting survival. Therefore, understanding how exactly coflin-1 plays, particularly in therapy resistance, may pave the way to the development of treatment strategies and improvement of patient survival.

Chaperone-mediated autophagy degrade Dicer to promote breast cancer metastasis

Metastasis in breast cancer usually lead to the majority of deaths on clinical patients. Accordingly, diagnosis of metastasis at the early stage in breast cancer is important to improve the prognosis. We observed that Dicer protein levels are significant decrease in highly invasive breast cancer cells and usually correlated with poor clinical outcomes. Following, we aim to clarify the molecular regulatory mechanism of this phenomenon in breast cancer to provide a new therapeutic target. In this study, we obtained that Dicer expression correlated with metastasis and invasion without affect cell stability in breast cancer cells. Importantly, we identified the regulatory mechanism of Dicer protein degradation, the chaperone-mediated autophagy (CMA)-mediated degradation that is major mechanism to decrease Dicer protein expression and lead to cancer metastasis. We discovered that heat shock cognate 71-kDa protein (Hsc70) which as a CMA-related factor interacts with the CMA-targeting motif I333A/K334A on Dicer to promote degradation through CMA. Taken together, our findings hint that Dicer highly correlated with cancer metastasis, we reveal the tumor-promoting effect of CMA-mediated Dicer degradation in breast cancer.

Small molecule RAF265 as an antiviral therapy acts against HSV-1 by regulating cytoskeleton rearrangement and cellular translation machinery

Host-targeting antivirals (HTAs) have received increasing attention for their potential as broad-spectrum antivirals that pose relatively low risk of developing drug resistance. The repurposing of pharmaceutical drugs for use as antivirals is emerging as a cost- and time- efficient approach to developing HTAs for the treatment of a variety of viral infections. In this study, we used a virus titer method to screen 30 small molecules for antiviral activity against Herpes simplex virus-1 (HSV-1). We found that the small molecule RAF265, an anticancer drug that has been shown to be a potent inhibitor of B-RAF V600E, reduced viral loads of HSV-1 by 4 orders of magnitude in Vero cells and reduced virus proliferation in vivo. RAF265 mediated cytoskeleton rearrangement and targeted the host cell's translation machinery, which suggests that the antiviral activity of RAF265 may be attributed to a dual inhibition strategy. This study offers a starting point for further advances toward clinical development of antivirals against HSV-1.

Cytoskeletal and Cytoskeleton-Associated Proteins: Key Regulators of Cancer Stem Cell Properties

Cancer stem cells (CSCs) are a subpopulation of cancer cells possessing stemness characteristics that are closely associated with tumor proliferation, recurrence and resistance to therapy. Recent studies have shown that different cytoskeletal components and remodeling processes have a profound impact on the behavior of CSCs. In this review, we outline the different cytoskeletal components regulating the properties of CSCs and discuss current and ongoing therapeutic strategies targeting the cytoskeleton. Given the many challenges currently faced in targeted cancer therapy, a deeper comprehension of the molecular events involved in the interaction of the cytoskeleton and CSCs will help us identify more effective therapeutic strategies to eliminate CSCs and ultimately improve patient survival.

Oxaloacetate acid ameliorates paraquat-induced acute lung injury by alleviating oxidative stress and mitochondrial dysfunction

Acute lung injury (ALI) is the primary cause of death among patients with acute paraquat (PQ) poisoning, whereby peroxidative damage is an important mechanism underlying PQ-induced lung injury. There is a lack of effective interventional drugs for patients with PQ poisoning. Oxaloacetic acid (OAA) participates in multiple in vivo metabolic processes, whereby it facilitates the clearance of reactive oxygen species (ROS) and improves mitochondrial function. The study aimed to assess the protective effects of OAA on PQ-induced ALI and elucidate the underlying molecular mechanism. Our data demonstrated that OAA treatment significantly alleviated PQ-induced ALI and improved the survival rate of PQ-poisoned mice, and also alleviated PQ-induced cellular oxidative stress and mitochondrial dysfunction. OAA-mediated alleviation of PQ-induced mitochondrial dysfunction depends on the following mechanisms which may explain the above findings: 1) OAA effectively cleared intracellular ROS, inhibited ROS accumulation, and mitochondrial depolarization; 2) OAA inhibited the downregulation of L-OPA1 and MFN2 caused by PQ and promoted a dynamic balance of mitochondrial fusion and fission, and 3) the expression of PGC-1α, TFAM, COX2, and COX4I1, increased significantly following OAA intervention which improved mitochondrial respiratory functions and promoted its biogenesis and energy metabolism in damaged cells. In conclusion, OAA effectively cleared ROS and improved mitochondrial dysfunction, thereby significantly improving ALI caused by PQ poisoning and the animal survival rate. Therefore, OAA may be a potential drug for the treatment of PQ poisoning.

Wrangling Actin Assemblies: Actin Ring Dynamics during Cell Wound Repair

To cope with continuous physiological and environmental stresses, cells of all sizes require an effective wound repair process to seal breaches to their cortex. Once a wound is recognized, the cell must rapidly plug the injury site, reorganize the cytoskeleton and the membrane to pull the wound closed, and finally remodel the cortex to return to homeostasis. Complementary studies using various model organisms have demonstrated the importance and complexity behind the formation and translocation of an actin ring at the wound periphery during the repair process. Proteins such as actin nucleators, actin bundling factors, actin-plasma membrane anchors, and disassembly factors are needed to regulate actin ring dynamics spatially and temporally. Notably, Rho family GTPases have been implicated throughout the repair process, whereas other proteins are required during specific phases. Interestingly, although different models share a similar set of recruited proteins, the way in which they use them to pull the wound closed can differ. Here, we describe what is currently known about the formation, translocation, and remodeling of the actin ring during the cell wound repair process in model organisms, as well as the overall impact of cell wound repair on daily events and its importance to our understanding of certain diseases and the development of therapeutic delivery modalities.

Calreticulin nuclear translocalization alleviates CaM/CaMKII/CREB signaling pathway to enhance chemosensitivity in HDAC inhibitor-resistant hepatocellular carcinoma cells

Calreticulin (CRT) is located in the endoplasmic reticulum (ER), it helps proteins fold correctly inside the ER, and acts as a modulator of Ca²⁺ homeostasis. Aberrant expression of CRT is implicated in several cancer types, qualifying CRT as a potential therapeutic target. However, it remains unclear how CRT affects specific oncogenic pathways. In this study, we used histone deacetylase inhibitors (HDACis) to establish drug-resistant liver cancer cells and further analyzed the molecular mechanism of development of drug resistance in those cells. The 2D gel electrophoresis and RT-PCR data showed that CRT was downregulated in HDACis-resistant cells by comparing with HA22T parental cells. We previously elucidated the development of drug-resistance in HCC cells via activation of PP1-eIF2α pathway, but not via ER stress pathway. Here, we show that thapsigargin induced ER stress through mechanism other than ER stress downstream protein GRP78-PERK to regulate CRT expression in HDACis-R cells. Moreover, the expression level of CRT was not the main cause of apoptosis in HDACis-resistant cells. Mechanistic studies identified the apoptosis factors in the nucleus-the HDACis-mediated overexpression of CRT, CRT translocation to the cell nucleus, and reduced CaM/CaMKII/CREB pathway-that led to chemosensitivity in HDACis-R HCC cells.

Combining histone deacetylase inhibitors (HDACis) with other therapies for cancer therapy

Histone deacetylases (HDACs) play an important role in regulating the expression of genes involved in tumorigenesis and tumor maintenance, and hence they have been considered as key targets in cancer therapy. As a novel category of antitumor agents, histone deacetylase inhibitors (HDACis) can induce cell cycle arrest, apoptosis, and differentiation in cancer cells, ultimately combating cancer. Although in the United States, the use of HDACis for the treatment of certain cancers has been approved, the therapeutic efficacy of HDACis as a single therapeutic agent in solid tumorshas been unsatisfactory and drug resistance may yet occur. To enhance therapeutic efficacy and limit drug resistance, numerous combination therapies involving HDACis in synergy with other antitumor therapies have been studied. In this review, we describe the classification of HDACs. Moreover, we summarize the antitumor mechanism of the HDACis for targeting key cellular processes of cancers (cell cycle, apoptosis, angiogenesis, DNA repair, and immune response). In addition, we outline the major developments of other antitumor therapies in combination with HDACis, including chemotherapy, radiotherapy, phototherapy, targeted therapy, and immunotherapy. Finally, we discuss the current state and challenges of HDACis-drugs combinations in future clinical studies, with the aim of optimizing the antitumor effect of such combinations.

Overexpressed Proteins in HCC Cell-Derived Exosomes, CCT8, and Cofilin-1 Are Potential Biomarkers for Patients with HCC

Protein markers of hepatocellular carcinoma (HCC)-derived exosomes (HEX) have not yet been fully evaluated. Here, we identified novel protein contents of HEX and their clinical significance as biomarkers. Exosomes were isolated from human HCC cell lines and an immortalized normal hepatocyte cell line. Proteomic analyses revealed 15 markedly overexpressed proteins in HEX. The clinical relevance of the 15 proteins was analyzed in public RNA-sequencing datasets, and 6 proteins were selected as candidate of potential biomarkers. Serum CCT8 and CFL1 were markedly overexpressed in test cohort (n = 8). In the validation cohort (n = 224), the area under the curve (AUC) of serum CCT8 and CFL1 for HCC diagnosis was calculated as 0.698 and 0.677, respectively, whereas that of serum alpha-fetoprotein (AFP) was 0.628. The combination of three serum markers (CCT8, CFL1, and AFP) demonstrated the highest AUC for HCC diagnosis. (AUC = 0.838, 95% confidence interval = 0.773–0.876) Furthermore, higher serum CCT8 and CFL1 concentrations were significantly associated with the presence of vascular invasion, advanced tumor stage, poor disease-free survival, and poor overall survival. Cofilin-1 and CCT8, enriched proteins in HEX, were identified as potential diagnostic and prognostic serum biomarkers for HCC patients.

Hsa-miR-107 regulates chemosensitivity and inhibits tumor growth in hepatocellular carcinoma cells

Hepatocellular carcinoma is a common type of liver cancer. Resistance to chemotherapeutic agents is a major problem in cancer therapy. MicroRNAs have been reported in cancer development and tumor growth; however, the relationship between chemoresistance and hepatocellular carcinoma needs to be fully investigated. Here, we treated hepatocellular carcinoma cell line (HA22T) with a histone deacetylase inhibitor to establish hepatocellular carcinoma-resistant cells (HDACi-R) and investigated the molecular mechanisms of chemoresistance in HCC cells. Although histone deacetylase inhibitor could not enhance cell death in HDACi-R but upregulation of miR-107 decreased cell viability both in parental cells and resistance cells, decreased the expression of cofilin-1, enhanced ROS-induced cell apoptosis, and dose-dependently sensitized HDACi-R to HDACi. Further, miR-107 upregulation resulted in tumor cell disorganization in both HA22T and HDACi-R in a mice xenograft model. Our findings demonstrated that miR-107 downregulation leads to hepatocellular carcinoma cell resistance in HDACi via a cofilin-1-dependent molecular mechanism and ROS accumulation.

Cyclovirobuxine D Induces Apoptosis and Mitochondrial Damage in Glioblastoma Cells Through ROS-Mediated Mitochondrial Translocation of Cofilin

Background

Cyclovirobuxine D (CVBD), a steroidal alkaloid, has multiple pharmacological activities, including anti-cancer activity. However, the anti-cancer effect of CVBD on glioblastoma (GBM) has seldom been investigated. This study explores the activity of CVBD in inducing apoptosis of GBM cells, and examines the related mechanism in depth.

Methods

GBM cell lines (T98G, U251) and normal human astrocytes (HA) were treated with CVBD. Cell viability was examined by CCK-8 assay, and cell proliferation was evaluated by cell colony formation counts. Apoptosis and mitochondrial superoxide were measured by flow cytometry. All protein expression levels were determined by Western blotting. JC-1 and CM-H₂DCFDA probes were used to evaluate the mitochondrial membrane potential (MMP) change and intracellular ROS generation, respectively. The cell ultrastructure was observed by transmission electron microscope (TEM). Colocalization of cofilin and mitochondria were determined by immunofluorescence assay.

Results

CVBD showed a greater anti-proliferation effect on the GBM cell lines, T98G and U251, than normal human astrocytes in dose- and time-dependent manners. CVBD induced apoptosis and mitochondrial damage in GBM cells. We found that CVBD led to mitochondrial translocation of cofilin. Knockdown of cofilin attenuated CVBD-induced apoptosis and mitochondrial damage. Additionally, the generation of ROS and mitochondrial superoxide was also induced by CVBD in a dose-dependent manner. N-acetyl-L-cysteine (NAC) and mitoquinone (MitoQ) pre-treatment reverted CVBD-induced apoptosis and mitochondrial damage. MitoQ pretreatment was able to block the mitochondrial translocation of cofilin caused by CVBD.

Conclusions

Our data revealed that CVBD induced apoptosis and mitochondrial damage in GBM cells. The underlying mechanism is related to mitochondrial translocation of cofilin caused by mitochondrial oxidant stress.

Hypoxia-induced cofilin 1 promotes hepatocellular carcinoma progression by regulating the PLD1/AKT pathway

BACKGROUND

Hepatocellular carcinoma (HCC) is the fourth fatal malignant tumour type worldwide. However, the exact molecular mechanism involved in HCC progression remains unclear.

METHODS

Three pairs of HCC and matched portal vein tumour thrombus (PVTT) tissue samples were analysed by isobaric tags for relative and absolute quantification (iTRAQ) assay to investigate the differentially expressed proteins. Real-time quantitative PCR, immunostaining, and immunoblotting were performed to detect cofilin 1 (CFL1) in HCC and non-tumour tissues. CCK8 and EdU, and Transwell assays, respectively, determined cell proliferation, migration, and invasion of HCC cells. Further, subcutaneous and tail vein injection were performed in nude mice for investigating HCC growth and lung metastasis in vivo. Regulatory effect of hypoxia-inducible factor-1α (HIF-1α) on CFL1 was confirmed by chromatin immunoprecipitation (ChIP) assay. Finally, interaction between CFL1 and phospholipase D1 (PLD1) was studied using immunoprecipitation (IP) assay.

RESULTS

The iTRAQ analysis identified expression of CFL1 to be significantly upregulated in PVTT than in HCC tissues. Increased expression of CFL1 was closely associated with unfavourable clinical features, and was an independent risk predictor of overall survival in HCC patients. The knockdown of CFL1 inhibited cell growth viability, invasiveness, and epithelial-mesenchymal transformation (EMT) in HCC cells. Furthermore, CFL1 silencing significantly suppressed the growth and lung metastasis of HCC cells in nude mice. Next, HIF-1α directly regulated CFL1 transcription by binding to the hypoxia-responsive element (HRE) in the promoter. Moreover, we disclosed the interaction between CFL1 and PLD1 in HCC cells using IP assay. Mechanistically, CFL1 maintained PLD1 expression by repressing ubiquitin-mediated protein degradation, thereby activating AKT signalling in HCC cells. Notably, the CFL1/PLD1 axis was found mediating the hypoxia-induced activation of the AKT pathway and EMT.

CONCLUSION

The analysis suggests that hypoxia-induced CFL1 increases the proliferation, migration, invasion, and EMT in HCC by activating the PLD1/AKT pathway.

Platycodin D reverses histone deacetylase inhibitor resistance in hepatocellular carcinoma cells by repressing ERK1/2-mediated cofilin-1 phosphorylation

BACKGROUND

Chemoresistance remains the main obstacle in hepatocellular carcinoma (HCC) therapy. Despite significant advances in HCC therapy, HCC still has a poor prognosis. Thus, there is an urgent need to identify a treatment target to reverse HCC chemotherapy resistance. Platycodon grandiflorus (PG) is a perennial herb that has been used as food and traditional Chinese medicine for thousands of years in Northeast Asia. Platycodin D (PD), a main active triterpenoid saponin found in the root of PG, has been reported to possess anticancer properties in several cancer cell lines, including HCC; however, the reversal effect of this molecule on HCC chemoresistance remains largely unknown.

PURPOSE

This study aimed to investigate the role and the mechanism of PD-mediated reversal of the histone deacetylase inhibitor (HDACi) resistance in HCC cells.

METHODS

Human HCC cells (HA22T) and HDACi-resistant (HDACi-R) cells were used. Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Combination index was used to calculate the synergism potential. Expression of ERK1/2 (total/phospho), cofilin-1 (total/phospho) and apoptosis-related protein was determined using western blotting. Mitochondrial membrane potential was assessed using the JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine iodide) probe. Apoptosis was detected using the terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Mitochondrial reactive oxygen species generation was measured using the MitoSOX Red fluorescent probe.

RESULTS

We found that PD treatment inhibited cell viability both in HA22T HCC and HDACi-R cells. Inhibition of ERK1/2 by PD98059 could reverse drug resistance in HDACi-R cells treated with PD98059 and PD. Nevertheless, pre-treatment with U46619, an ERK1/2 activator, rescued PD-induced apoptosis by decreasing levels of apoptosis-related proteins in HCC cells. The combined treatment of PD with apicidin a powerful HDACi, dramatically enhanced the apoptotic effect in HDACi-R cells.

CONCLUSION

For the first time, we showed that PD reversed HDACi resistance in HCC by repressing ERK1/2-mediated cofilin-1 phosphorylation. Thus, PD can potentially be a treatment target to reverse HCC chemotherapy resistance in future therapeutic trials.

Role of cofilin‑1 in arsenic trioxide‑induced apoptosis of NB4‑R1 cells

All-trans retinoic acid (ATRA) and arsenic trioxide (As₂O₃) are currently first-line treatments for acute promyelocytic leukemia (APL). However, a number of patients with APL are resistant to ATRA but still sensitive to As₂O₃, and the underlying mechanisms of this remain unclear. In the present study, two-dimensional gel electrophoresis, mass spectrometry and other proteomic methods were applied to screen and identify the differentially expressed proteins between the retinoic acid-sensitive cell lines and drug-resistant cell lines. The results demonstrated that in retinoic acid-resistant NB4-R1 cells, the protein expression of cofilin-1 was markedly increased compared with that in the drug-sensitive NB4 cells. Subsequently, the effects of cofilin-1 on As₂O₃-induced apoptosis in NB4-R1 cells were further investigated. The results revealed that cell viability was markedly suppressed and apoptosis was increased in the As₂O₃-treated NB4-R1 cells, with increased expression levels of cleaved-poly (ADP-ribose) polymerase and cleaved-caspase 12. Cofilin-1 expression was significantly decreased at both the mRNA and protein levels in the As₂O₃-treated group compared with the control. Western blotting further revealed that As₂O₃ treatment decreased the cytoplasmic cofilin-1 level but increased its expression in the mitochondrion. However, the opposite effects of As₂O₃ on the cytochrome C distribution were found in NB4-R1 cells. This suggested that As₂O₃ can induce the transfer of cofilin-1 from the cytoplasm to mitochondria and trigger the release of mitochondrial cytochrome C in NB4-R1 cells. Moreover, cofilin-1 knockdown by its specific short hairpin RNA significantly suppressed As₂O₃-induced NB4-R1 cell apoptosis and inhibited the release of mitochondrial cytochrome C. Whereas, overexpression of cofilin-1 using a plasmid vector carrying cofilin-1 increased the release of cytochrome C into the cytoplasm from the mitochondria in As₂O₃-treated NB4-R1 cells. In conclusion, cofilin-1 played a role in As₂O₃-induced NB4-R1 cell apoptosis and it might be a novel target for APL treatment.

Moving Pieces in a Cellular Puzzle: A Cryptic Peptide from the Scorpion Toxin Ts14 Activates AKT and ERK Signaling and Decreases Cardiac Myocyte Contractility via Dephosphorylation of Phospholamban

Cryptic peptides (cryptides) are biologically active peptides formed after proteolysis of native precursors present in animal venoms, for example. Proteolysis is an overlooked post-translational modification that increases venom complexity. The tripeptide KPP (Lys-Pro-Pro) is a peptide encrypted in the C-terminus of Ts14-a 25-mer peptide from the venom of the Tityus serrulatus scorpion that has a positive impact on the cardiovascular system, inducing vasodilation and reducing arterial blood pressure of hypertensive rats among other beneficial effects. A previous study reported that KPP and its native peptide Ts14 act via activation of the bradykinin receptor B2 (B2R). However, the cellular events underlying the activation of B2R by KPP are unknown. To study the cell signaling triggered by the Ts14 cryptide KPP, we incubated cardiac myocytes isolated from C57BL/6 mice with KPP (10^-7 mol·L^-1) for 0, 5, or 30 min and explored the proteome and phosphoproteome. Our results showed that KPP regulated cardiomyocyte proteins associated with, but not limited to, apoptosis, muscle contraction, protein turnover, and the respiratory chain. We also reported that KPP led to AKT phosphorylation, activating AKT and its downstream target nitric oxide synthase. We also observed that KPP led to dephosphorylation of phospholamban (PLN) at its activation sites (S16 and T17), leading to reduced contractility of treated cardiomyocytes. Some cellular targets reported here for KPP (e.g., AKT, PLN, and ERK) have already been reported to protect the cardiac tissue from hypoxia-induced injury. Hence, this study suggests potential beneficial effects of this scorpion cryptide that needs to be further investigated, for example, as a drug lead for cardiac infarction.

Systematical identification of cell-specificity of CTCF-gene binding based on epigenetic modifications

The CCCTC-binding factor (CTCF) mediates transcriptional regulation and implicates epigenetic modifications in cancers. However, the systematically unveiling inverse regulatory relationship between CTCF and epigenetic modifications still remains unclear, especially the mechanism by which histone modification mediates CTCF binding. Here, we developed a systematic approach to investigate how epigenetic changes affect CTCF binding. Through integration analysis of CTCF binding in 30 cell lines, we concluded that CTCF generally binds with higher intensity in normal cell lines than that in cancers, and higher intensity in genome regions closed to transcription start sites. To facilitate the better understanding of their associations, we constructed linear mixed-effect models to analyze the effects of the epigenetic modifications on CTCF binding in four cancer cell lines and six normal cell lines, and identified seven epigenetic modifications as potential epigenetic patterns that influence CTCF binding intensity in promoter regions and six epigenetic modifications in enhancer regions. Further analysis of the effects in different locations revealed that the epigenetic regulation of CTCF binding was location-specific and cancer cell line-specific. Moreover, H3K4me2 and H3K9ac showed the potential association with immune regulation of disease. Taken together, our method can contribute to improve the understanding of the epigenetic regulation of CTCF binding and provide potential therapeutic targets for treating tumors associated with CTCF.

Combinatorial photochemotherapy on liver cancer stem cells with organoplatinum(ii) metallacage-based nanoparticles

Liver cancer is a kind of lethal and aggressive malignant neoplasm with a high rate of relapse and metastasis after therapy. An important cause for the relapse and metastasis is the existence of liver cancer stem cells (CSCs), which have high resistance to chemotherapy and high tumorigenic potential. Therefore, it is crucial to develop new methods to eradicate CSCs in tumors. Herein, we develop a photodynamic therapy (PDT) that features bimodal metallacage-loaded nanoparticles (MNPs) for integrated chemotherapy. This platform achieves chemo-photodynamic combinational therapy. Organoplatinum(ii) metallacage-loaded nanoparticles show excellent ability to kill liver CSCs, decreasing their mobility and sphenoid formation ability under near-infrared laser irradiation. Importantly, MNPs can successfully penetrate into 3D tumor spheroids, which display higher drug resistance compared to traditional 2D cultured cells. This destroys CSCs and prevents subsequent tumor formation in vivo. With the excellent combinational therapeutic results in hand, the working mechanisms of MNPs were then studied. MNPs under NIR light irradiation can generate reactive oxygen species (ROS), resulting in damage of mitochondrial membrane and subsequent cell apoptosis with chemotherapeutic platinum. This study proves the great potential of MNPs for combinational cancer therapy, providing a new insight for the next generation of nanomedicines.

Hydrogen Sulfide Attenuates Hydrogen Peroxide-Induced Injury in Human Lung Epithelial A549 Cells

Lung tissues are frequently exposed to a hyperoxia environment, which leads to oxidative stress injuries. Hydrogen sulfide (H₂S) is widely implicated in physiological and pathological processes and its antioxidant effect has attracted much attention. Therefore, in this study, we used hydrogen peroxide (H₂O₂) as an oxidative damage model to investigate the protective mechanism of H₂S in lung injury. Cell death induced by H₂O₂ treatment could be significantly attenuated by the pre-treatment of H₂S, resulting in a decrease in the Bax/Bcl-2 ratio and the inhibition of caspase-3 activity in human lung epithelial cell line A549 cells. Additionally, the results showed that H₂S decreased reactive oxygen species (ROS), as well as neutralized the damaging effects of H₂O₂ in mitochondria energy-producing and cell metabolism. Pre-treatment of H₂S also decreased H₂O₂-induced suppression of endogenous H₂S production enzymes, cystathionine-beta-synthase (CBS), cystathionine-gamma-lyase (CSE), and 3-mercapto-pyruvate sulfurtransferase (MPST). Furthermore, the administration of H₂S attenuated [Ca²⁺] overload and endoplasmic reticulum (ER) stress through the mitogen-activated protein kinase (MAPK) signaling pathway. Therefore, H₂S might be a potential therapeutic agent for reducing ROS and ER stress-associated apoptosis against H₂O₂-induced lung injury.

Inhibition of protein phosphatase 1 stimulates noncanonical ER stress eIF2α activation to enhance fisetin-induced chemosensitivity in HDAC inhibitor-resistant hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC) is a common fatal type of malignant tumor that has highly metastatic and recurrent properties. Fisetin is a natural flavonoid found in various vegetables and fruits which exhibits anti-cancer and anti-inflammatory properties, as well as other effects. Thus, we hypothesized that fisetin can act as an adjuvant therapy in cancer or drug-resistant cancer cells, and further investigated the molecular mechanisms underlying the development of drug-resistance in HCC cells. We found that fisetin effectively inhibited the cell viability of not only parental cells but also histone deacetylase inhibitors-resistant (HDACis-R) cells and enhanced the chemosensitivity of HCC cells. Interestingly, fisetin did not induce cell apoptosis through the activation of the endoplasmic reticulum (ER) stress sensor of protein kinase R (PKR)-like endoplasmic reticulum kinase, but rather through the non-canonical pathway of the protein phosphatase 1 (PP1)-mediated suppression of eIF2α phosphorylation. Moreover, fisetin-induced cell apoptosis was reversed by treatment with PP1 activator or eIF2α siRNA in HCC cells. Based on these observations, we suggest that PP1-eIF2α pathways are significantly involved in the effect of fisetin on HCC apoptosis. Thus, fisetin may act as a novel anticancer drug and new chemotherapy adjuvant which can improve the efficacy of chemotherapeutic agents and diminish their side-effects.

Combination treatment strategy for pancreatic cancer involving the novel HDAC inhibitor MPT0E028 with a MEK inhibitor beyond K-Ras status

BACKGROUND

Oncogenic K-Ras signaling highly relies on the canonical Ras/MEK/ERK pathway to contribute to pancreatic cancer progression. However, numerous efforts of MEK inhibitors have failed to provide an optimal antitumor effect for pancreatic cancer in practice. The aim of the present work was to develop a more efficacious therapeutic intervention for MEK inhibitors through combination with histone deacetylase (HDAC) inhibitor MPT0E028.

METHODS

The effects of combined therapy on cell viability, apoptosis, protein, and RNA expressions were determined by MTT assay, flow cytometry, western blotting, and quantitative PCR analysis. The AsPC-1 xenograft was used to assess antitumor effects in vivo.

RESULTS

The co-administration of MPT0E028 and MEK inhibitor yielded synergistic effects on cell viability suppression both in K-Ras mutated and wild-type pancreatic cancer cells and also markedly triggered cell apoptosis. Surprisingly, ERK and epidermal growth factor receptor (EGFR) were activated by the long-term and low-concentration treatment of MPT0E028 or another HDAC inhibitor alone. Whereas, the pharmacological attenuation of ERK signaling dramatically abolished the MPTE028-induced p-ERK and EGFR expression. Overexpression of HDAC4, HDAC6, and MEK, respectively, reversed the cell death induced by the combined treatment. Finally, the combined treatment decreased the tumor volume in an AsPC-1 xenograft model compared to each individual treatment alone.

CONCLUSIONS

The synergistic anti-survival effect of the combination was suggested to occur via compensation of the MEK inhibitor for activated ERK. Our results indicate that this combination strategy could benefit patients with pancreatic cancer beyond K-Ras status.

Oxaloacetate Ameliorates Chemical Liver Injury via Oxidative Stress Reduction and Enhancement of Bioenergetic Fluxes

Chemical injury is partly due to free radical lipid peroxidation, which can induce oxidative stress and produce a large number of reactive oxygen species (ROS). Oxaloacetic acid is an important intermediary in the tricarboxylic acid cycle (TCA cycle) and participates in metabolism and energy production. In our study, we found that oxaloacetate (OA) effectively alleviated liver injury which was induced by hydrogen peroxide (H₂O₂) in vitro and carbon tetrachloride (CCl₄) in vivo. OA scavenged ROS, prevented oxidative damage and maintained the normal structure of mitochondria. We further confirmed that OA increased adenosine triphosphate (ATP) by promoting the TCA production cycle and oxidative phosphorylation (OXPHOS). Finally, OA inhibited the mitogen-activated protein kinase (MAPK) and apoptotic pathways by suppressing tumor necrosis factor-α (TNF-α). Our findings reveal a mechanism for OA ameliorating chemical liver injury and suggest a possible implementation for preventing the chemical liver injury.

Platycodin D Reverses Pathological Cardiac Hypertrophy and Fibrosis in Spontaneously Hypertensive Rats

Platycodin D (PD) is the main active saponin isolated from Platycodon grandiflorum (PG) and is reported to exhibit anticancer, anti-angiogenic, anti-inflammation and anti-obesity biological effects. The current study aims to evaluate the therapeutic efficacy of PD in cardiac fibrosis and for hypertrophy in spontaneous hypertension rats (SHRs) and to verify inhibition of the signaling pathway. Significant increases in the cardiac functional indices of left ventricular internal diameter end diastole (LVIDd) and left ventricular internal diameter end systole (LVIDs); the eccentric hypertrophy marker p-MEK5; concentric hypertrophy markers, such as CaMKII[Formula: see text] and calcineurin; and expression levels of NFATc3, p-GATA4 and BNP were observed in spontaneously hypertensive groups. PD treatment reversed these increases in SHRs. In addition, an increase in the fibrosis markers FGF2, uPA, MMP2, MMP9, TGF[Formula: see text]-1 and CTGF during cardiac hypertrophy was detected by western blotting analyses. These results demonstrated that PD treatment considerably attenuates cardiac fibrosis. Histopathological examination revealed that PD treatment remarkably reduced collagen accumulation in contrast to spontaneously hypertensive groups. This study clearly suggests that PD provides myocardial protection by alleviating two damaging responses to hypertension, fibrosis and hypertrophy, in the heart.

Cofilin-2 Acts as a Marker for Predicting Radiotherapy Response and Is a Potential Therapeutic Target in Nasopharyngeal Carcinoma

Background

The purpose of this study was to determine whether cofilin-2 could serve as a protein marker for predicting radiotherapy response and as a potential therapeutic target in nasopharyngeal carcinoma (NPC).

Material/Methods

Cofilin-2 protein levels in serum and tissue samples from patients with NPC were assessed by sandwich ELISA and IHC. In vitro, cofilin-2 levels in CNE-2R cells were significantly higher than those of CNE-2 cells. Meanwhile, CNE-2R cells were silenced for cofilin-2 to obtain a stable cofilin-2-RNAi-LV3 cell line. Then, cell proliferation, radiosensitivity, invasion and migration abilities, cell cycle, and apoptosis were evaluated by Cell Counting Kit 8 assay (CCK-8), flow cytometry (FCM), clone formation assay, and in vitro.

Results

The secreted levels of the cofilin-2 protein in radioresistant NPC patients were significantly higher than those of radiosensitive cases. After cofilin-2 knockdown in nasopharyngeal carcinoma CNE-2R cells, proliferation was decreased, while apoptosis and radiosensitivity were enhanced; cell cycle distribution was altered, and the transplanted tumors in nude mice grew significantly less.

Conclusions

Overall, our findings suggest that cofilin-2 acts as a marker for predicting radiotherapy response and is a potential therapeutic target in nasopharyngeal carcinoma.

Zinc phthalocyanine encapsulated in polymer micelles as a potent photosensitizer for the photodynamic therapy of osteosarcoma

Zinc phthalocyanine (ZnPc) is a highly potent second-generation photosensitizer for cancer photodynamic therapy (PDT) with attractive photo-physical and photo-chemical properties. However, poor solubility and strong trend of crystallization prevent it from loading in most of drug delivery systems and hamper its further application. Herein, to overcome this problem, an amphiphilic block copolymer poly(ethylene glycol)-poly[2-(methylacryloyl)ethylnicotinate] (PEG-PMAN) with aromatic nicotinate is used to load ZnPc for their π-π interactions. The formed PEG-PMAN/ZnPc nanoparticle (PPZ) dramatically increases reactive oxygen species production in osteosarcoma cells after light irradiation, causes mitochondrial injury and promotes cell cycle arrest at G2/M, leading to a 100-fold cytotoxicity improvement comparing with free ZnPc. The excellent therapeutic effectiveness and safety of PPZ are also proved by in vivo experiments operating on osteosarcoma model. The finding above indicates that PPZ has promising clinical applications as a next-generation photosensitizer in PDT of osteosarcoma.

Distinct signaling events promote resistance to mitoxantrone and etoposide in pediatric AML: a Children's Oncology Group report

Despite aggressive chemotherapy including mitoxantrone and etoposide, relapse occurs for almost half of children with acute myeloid leukemia (AML). Since both drugs inhibit topoisomerase II and cause DNA double strand breaks, resistance could be achieved by enhanced DNA damage repair (DDR), via homologous recombination (HR) and/or non-homologous end joining (NHEJ). An important source of extrinsic chemoresistance is the bone marrow stroma. We aimed to reveal intrinsic and stroma-induced signaling pathways that contribute to chemoresistance. Sixty diagnostic pediatric AML samples were cultured on or off stromal cells, with or without chemotherapy. We measured apoptosis, DNA damage signaling, and NHEJ/HR pathway activity by FACS analysis of intracellular cleaved PARP, γH2AX, pDNA-PKcs and pATM, respectively. Mitoxantrone strongly increased γH2AX and pDNA-PKcs. Neither chemotherapy drug induced pATM. DNA-PK inhibition alleviated mitoxantrone resistance for AML cells on and off stromal cells. Regarding stroma-induced signaling pathways, ERK1/2 was most consistently activated in primary AML cells by stromal cells. ERK1/2 inactivation partially restored chemosensitivity to AML cells on stromal cells. Additionally, low stroma-induced STAT3 activity and strong stroma-induced mitoxantrone resistance were associated with inferior clinical outcome. Taken together, the NHEJ DDR and ERK1/2 pathways are potential targets for reducing intrinsic and extrinsic chemotherapy resistance in pediatric AML.

Histone deacetylase inhibitor quisinostat activates caspase signaling and upregulates p53 acetylation to inhibit the proliferation of HepG2 cells

Histone deacetylase inhibitor (HDACi) has been a major target of anticancer agents. Quisinostat (JNJ‑26481585), a novel second‑generation HDACi, has previously demonstrated antiproliferative activity against non‑small cell lung cancer; however, the function of quisinostat in hepatocellular carcinoma (HCC) remains to be elucidated. In the present study, it was revealed that quisinostat suppressed the cell viability of HepG2 cells in vitro and in vivo. Increased cell apoptosis was observed in quisinostat‑treated HepG2 cells. The underlying mechanism revealed that quisinostat treatment activates the cleavage of caspase proteins. Furthermore, quisinostat upregulated p53 acetylation at K381/K382 sites by impairing the interaction between histone deacetylase 6 and p53, which resulted in the activation of p53, and triggered cell cycle arrest at the G1 phase. Collectively, the results of the present study demonstrated the antiproliferative effect of quisinostat on HepG2 cells; these results suggest that histone deacetylase may be a promising therapeutic target of HCC.

Chemotherapy for hepatocellular carcinoma: The present and the future

Hepatocellular carcinoma (HCC) is the most common primary tumor of the liver. Its relationship to chronic liver diseases, in particular cirrhosis, develops on a background of viral hepatitis, excessive alcohol intake or metabolic steatohepatitis, leads to a high incidence and prevalence of this neoplasia worldwide. Despite the spread of HCC, its treatment it’s still a hard challenge, due to high rate of late diagnosis and to lack of therapeutic options for advanced disease. In fact radical surgery and liver transplantation, the most radical therapeutic approaches, are indicated only in case of early diagnosis. Even local therapies, such as transarterial chemoembolization, find limited indications, leading to an important problem regarding treatment of advanced disease. In this situation, until terminal HCC occurs, systemic therapy is the only possible approach, with sorafenib as the only standard treatment available. Anyway, the efficacy of this drug is limited and many efforts are necessary to understand who could benefit more with this treatment. Therefore, other molecules for a targeted therapy were evaluated, but only regorafenib showed promising results. Beside molecular target therapy, also cytotoxic drugs, in particular oxaliplatin- and gemcitabine-based regimens, and immune-checkpoint inhibitors were tested with interesting results. The future of the treatment of this neoplasia is linked to our ability to understand its mechanisms of resistance and to find novel therapeutic targets, with the objective to purpose individualized approaches to patients affected by advanced HCC.

Oxidative Stress Gene Expression Profile Correlates with Cancer Patient Poor Prognosis: Identification of Crucial Pathways Might Select Novel Therapeutic Approaches

The role of altered redox status and high reactive oxygen species (ROS) is still controversial in cancer development and progression. Intracellular levels of ROS are elevated in cancer cells suggesting a role in cancer initiation and progression; on the contrary, ROS elevated levels may induce programmed cell death and have been associated with cancer suppression. Thus, it is crucial to consider the double-face of ROS, for novel therapeutic strategies targeting redox regulatory mechanisms. In this review, in order to derive cancer-type specific oxidative stress genes' profile and their potential prognostic role, we integrated a publicly available oxidative stress gene signature with patient survival data from the Cancer Genome Atlas database. Overall, we found several genes statistically significant associated with poor prognosis in the examined six tumor types. Among them, FoxM1 and thioredoxin reductase1 expression showed the same pattern in four out of six cancers, suggesting their specific critical role in cancer-related oxidative stress adaptation. Our analysis also unveiled an enriched cellular network, highlighting specific pathways, in which many genes are strictly correlated. Finally, we discussed novel findings on the correlation between oxidative stress and cancer stem cells in order to define those pathways to be prioritized in drug development.