Bcl-2 inhibition of autophagy: a new route to cancer?

Small molecules targeting HDAC6 for cancer treatment: Current progress and novel strategies

Histone deacetylase 6 (HDAC6) plays a crucial role in the initiation and progression of various cancers, as its overexpression is linked to tumor growth, invasion, migration, survival, apoptosis, and angiogenesis. Therefore, HDAC6 has emerged as an attractive target for anticancer drug discovery in the past decade. However, the development of conventional HDAC6 inhibitors has been hampered by their limited clinical efficacy, acquired resistance, and inability to inhibit non-enzymatic functions of HDAC6. To overcome these challenges, new strategies, such as dual-acting inhibitors, targeted protein degradation (TPD) technologies (including PROTACs, HyT), are essential to enhance the anticancer activity of HDAC6 inhibitors. In this review, we focus on the recent advances in the design and development of HDAC6 modulators, including isoform-selective HDAC6 inhibitors, HDAC6-based dual-target inhibitors, and targeted protein degraders (PROTACs, HyT), from the perspectives of rational design, pharmacodynamics, pharmacokinetics, and clinical status. Finally, we discuss the challenges and future directions for HDAC6-based drug discovery for cancer therapy.

Ursodeoxycholic acid loaded dual-modified graphene oxide nanocomposite alleviates cholestatic liver injury through inhibiting hepatocyte apoptosis

Ursodeoxycholic acid (UDCA) is the preferred treatment for various types of cholestasis, however, its effectiveness is limited because of its insolubility in water. We used polyethylene glycol (PEG) and cationic polymer polyethylenimine (PEI) to double-modify graphite oxide (PPG) as a drug delivery system. UDCA was successfully loaded onto PPG through intermolecular interactions to form UDCA-PPG nanoparticles. UDCA-PPG nanoparticles not only improve the solubility and dispersibility of UDCA, but also have good biocompatibility and stability, which significantly improve the delivery rate of UDCA. The results indicated that UDCA-PPG significantly reduced ROS levels, promoted cell proliferation, protected mitochondrial membrane potential, reduced DNA damage and reduced apoptosis in the DCA-induced cell model. In a mouse cholestasis model established by bile duct ligation (BDL), UDCA-PPG improved liver necrosis, fibrosis, and mitochondrial damage and reduced serum ALT and AST levels, which were superior to those in the UDCA-treated group. UDCA-PPG reduced the expression of the apoptosis-related proteins, Caspase-3 and Bax, increased the expression of Bcl-2, and reduced the expression of the oxidative stress-related proteins, NQO and HO-1, as well as the autophagy-related proteins LC3, p62 and p-p62. Therefore, UDCA-PPG can enhance the therapeutic effect of UDCA in cholestasis, by significantly improving drug dispersibility and stability, extending circulation time in vivo, promoting absorption, decreasing ROS levels, enhancing autophagy flow and inhibiting apoptosis via the Bcl-2/Bax signaling pathway.

Natural products targeting autophagy and apoptosis in NSCLC: a novel therapeutic strategy

Lung cancer is the leading cause of cancer-related mortality worldwide, with non-small cell lung cancer (NSCLC) being the predominant type. The roles of autophagy and apoptosis in NSCLC present a dual and intricate nature. Additionally, autophagy and apoptosis interconnect through diverse crosstalk molecules. Owing to their multitargeting nature, safety, and efficacy, natural products have emerged as principal sources for NSCLC therapeutic candidates. This review begins with an exploration of the mechanisms of autophagy and apoptosis, proceeds to examine the crosstalk molecules between these processes, and outlines their implications and interactions in NSCLC. Finally, the paper reviews natural products that have been intensively studied against NSCLC targeting autophagy and apoptosis, and summarizes in detail the four most retrieved representative drugs. This paper clarifies good therapeutic effects of natural products in NSCLC by targeting autophagy and apoptosis and aims to promote greater consideration by researchers of natural products as candidates for anti-NSCLC drug discovery.

Natural products targeting macroautophagy signaling in hepatocellular carcinoma therapy: Recent evidence and perspectives

Hepatocellular carcinoma (HCC), presently the second leading cause of global cancer-related mortality, continues to pose significant challenges in the realm of medical oncology, impacting both clinical drug selection and mechanistic research. Recent investigations have unveiled autophagy-related signaling as a promising avenue for HCC treatment. A growing body of research has highlighted the pivotal role of autophagy-modulating natural products in inhibiting HCC progression. In this context, we provide a concise overview of the fundamental autophagy mechanism and delineate the involvement of autophagic signaling pathways in HCC development. Additionally, we review pertinent studies demonstrating how natural products regulate autophagy to mitigate HCC. Our findings indicate that natural products exhibit cytotoxic effects through the induction of excessive autophagy, simultaneously impeding HCC cell proliferation by autophagy inhibition, thereby depriving HCC cells of essential energy. These effects have been associated with various signaling pathways, including PI3K/AKT, MAPK, AMPK, Wnt/β-catenin, Beclin-1, and ferroautophagy. These results underscore the considerable therapeutic potential of natural products in HCC treatment. However, it is important to note that the present study did not establish definitive thresholds for autophagy induction or inhibition by natural products. Further research in this domain is imperative to gain comprehensive insights into the dual role of autophagy, equipping us with a better understanding of this double-edged sword in HCC management.

Autophagy activity is increased in the cumulus cells of women with poor ovarian response

OBJECTIVE

To evaluate the autophagy status of cumulus cells (CCs) in women with poor ovarian response (POR).

MATERIALS AND METHODS

CCs were divided into normal ovarian response (NOR) group and POR group. The ultrastructure of autophagy was analyzed by transmission electron microscopy (NOR: n = 18, POR: n = 26). The mRNA and protein of autophagy markers were detected by Quantitative real-time polymerase chain reaction (NOR: n = 15, POR: n = 19) and Western blotting (NOR: n = 41, POR: n = 38), respectively.

RESULTS

Transmission electron microscopy demonstrated abundant autophagosomes and even autophagic death in the POR group. There were no differences in LC3 and P62 mRNA expression between the two groups (p > 0.05). The BCL2 mRNA expression was lower in the POR group (p < 0.05). Moreover, the LC3 II/I ratio and the P62 protein expression were significantly higher in the POR group (p < 0.05).

CONCLUSIONS

Autophagy in CCs of POR women is activated and the autophagic flux is blocked. The up-regulation of autophagy in CCs may be related to the pathogenesis of POR.

Deregulation of circRNA hsa_circ_0009109 promotes tumor growth and initiates autophagy by sponging miR-544a-3p in gastric cancer

Background

Autophagy death of cancer cells is detrimental to apoptosis induced by therapeutic drugs, which promotes tumor progression to a certain extent. Increasing reports have demonstrated the regulatory role of circular RNAs (circRNAs) in autophagy. Here, we aimed to determine the role of hsa_circ_0009109 in autophagy in gastric cancer (GC).

Methods

The effects of hsa_circ_0009109 on autophagy were examined using quantitative real-time polymerase chain reaction (qPCR), transmission electron microscopy, Western blot, and immunofluorescence. The mechanism of hsa_circ_0009109 regulating the miR-544a-3p/bcl-2 axis was analysed using fluorescence in situ hybridization, dual-luciferase reporter, and rescue experiments.

Results

Functional testing indicated that hsa_circ_0009109 was significantly down-expressed in GC tissues and cell lines. A reduction in cytoplasmic-derived hsa_circ_0009109 could promote GC progression by accelerating cell proliferation, enhancing migration and invasion, inhibiting apoptosis, and accelerating the cell cycle progression. Besides, hsa_circ_0009109 was found to exert the effect of an autophagy inhibitor such as 3-Methyladenine (3-MA), which was manifested by the weakening of the immunofluorescence of LC3B and the reduction in autophagy-related proteins after overexpression of hsa_circ_0009109, while increased autophagosomes were observed after interference with hsa_circ_0009109. Subsequently, the crosstalk between hsa_circ_0009109 and miR-544a-3p/bcl-2 was verified using dual-luciferase reporter assay. The autophagy status was altered under the regulation of the hsa_circ_0009109-targeted miR-544a-3p/bcl-2 axis.

Conclusions

The hsa_circ_0009109 mediated a novel autophagy regulatory network through targeting the miR-544a-3p/bcl-2 axis, which may shed new light on the exploration of therapeutic targets for the clinical treatment of GC.

Resistance to abemaciclib is associated with increased metastatic potential and lysosomal protein deregulation in breast cancer cells

Cyclin dependent kinase 4 and 6 inhibitors such as abemaciclib are routinely used to treat metastatic estrogen receptor positive (ER+) breast cancer. However, adaptive mechanisms inhibit their effectiveness and allow for disease progression. Using ER+ breast cancer cell models, we show that acquired resistance to abemaciclib is accompanied by increase in metastatic potential. Mass spectrometry-based proteomics from abemaciclib sensitive and resistant cells showed that lysosomal proteins including CTSD (cathepsin D), cathepsin A and CD68 were significantly increased in resistant cells. Combination of abemaciclib and a lysosomal destabilizer, such as hydroxychloroquine (HCQ) or bafilomycin A1, resensitized resistant cells to abemaciclib. Also, combination of abemaciclib and HCQ decreased migration and invasive potential and increased lysosomal membrane permeability in resistant cells. Prosurvival B cell lymphoma 2 (BCL2) protein levels were elevated in resistant cells, and a triple treatment with abemaciclib, HCQ, and BCL2 inhibitor, venetoclax, significantly inhibited cell growth compared to treatment with abemaciclib and HCQ. Furthermore, resistant cells showed increased levels of Transcription Factor EB (TFEB), a master regulator of lysosomal-autophagy genes, and siRNA mediated knockdown of TFEB decreased invasion in resistant cells. TFEB was found to be mutated in a subset of invasive human breast cancer samples, and overall survival analysis in ER+, lymph node-positive breast cancer showed that increased TFEB expression correlated with decreased survival. Collectively, we show that acquired resistance to abemaciclib leads to increased metastatic potential and increased levels of protumorigenic lysosomal proteins. Therefore, the lysosomal pathway could be a therapeutic target in advanced ER+ breast cancer.

Crucial role of autophagy in propofol-treated neurological diseases: a comprehensive review

Neurological disorders are the leading cause of disability and death globally. Currently, there is a significant concern about the therapeutic strategies that can offer reliable and cost-effective treatment for neurological diseases. Propofol is a widely used general intravenous anesthetic in the clinic. Emerging studies demonstrate that propofol exerts neuroprotective effects on neurological diseases and disorders, while its underlying pathogenic mechanism is not well understood. Autophagy, an important process of cell turnover in eukaryotes, has been suggested to involve in the neuroprotective properties developed by propofol. In this narrative review, we summarized the current evidence on the roles of autophagy in propofol-associated neurological diseases. This study highlighted the effect of propofol on the nervous system and the crucial roles of autophagy. According to the 21 included studies, we found that propofol was a double-edged sword for neurological disorders. Several eligible studies reported that propofol caused neuronal cell damage by regulating autophagy, leading to cognitive dysfunction and other neurological diseases, especially high concentration and dose of propofol. However, some of them have shown that in the model of existing nervous system diseases (e.g., cerebral ischemia-reperfusion injury, electroconvulsive therapy injury, cobalt chloride-induced injury, TNF-α-induced injury, and sleep deprivation-induced injury), propofol might play a neuroprotective role by regulating autophagy, thus improving the degree of nerve damage. Autophagy plays a pivotal role in the neurological system by regulating oxidative stress, inflammatory response, calcium release, and other mechanisms, which may be associated with the interaction of a variety of related proteins and signal cascades. With extensive in-depth research in the future, the autophagic mechanism mediated by propofol will be fully understood, which may facilitate the feasibility of propofol in the prevention and treatment of neurological disorders.

Cowanin induces apoptosis in breast cancer cells via Bcl-2 signaling pathway

OBJECTIVES

This study aimed to investigate the effect of cowanin the mechanism of cowanin toward cell death and BCL-2 protein (antiapoptotic) expression of T47D breast cancer.

METHODS

The cell death was evaluated by double staining, namely acridine orange and propidium iodide, and then observed under a fluorescence microscope. Meanwhile, the BCL-2 protein expression was determined by western blotting with measurement of protein area and protein density.

RESULTS

The result found T47D breast cancer cells were viable, apoptosis, and necrosis after treatment with cowanin. The average viable cells, apoptosis, and necrosis percentages were 54.13 %, 45.43 %, and 0.44 %, respectively. Statistical analysis showed cowanin could significantly induce death in T47D breast cancer cells by apoptosis (p<0.05). It was also revealed that cowanin and positive control (doxorubicin) treatment had a significantly decreased protein area and protein density (p<0.05).

CONCLUSIONS

It can be concluded that cowanin can induce death in T47D breast cancer cells by apoptosis and affect the expression of Bcl-2 protein in T47D breast cancer cells.

High BECN1 Expression Negatively Correlates with BCL2 Expression and Predicts Better Prognosis in Diffuse Large B-Cell Lymphoma: Role of Autophagy

Diffuse large B-cell lymphoma (DLBCL) is characterized by high molecular and clinical heterogeneity. Autophagy, a lysosome-driven catabolic process devoted to macromolecular turnover, is fundamental in maintaining normal hematopoietic stem cells and progenitors homeostasis, and its dysregulation plays a critical role in the initiation and progression of hematological malignancies. One main regulator of autophagy is BECLIN-1, which may interact alternatively with either BCL-2, thus allowing apoptosis, or PI3KC3, thus promoting autophagy. The altered expression of BCL2 and BECN1 correlates with lymphoma outcomes, but whether this is associated with dysregulated cross-talk between autophagy and apoptosis remains to be elucidated. Analysis of the TCGA database revealed that BCL2 and BECN1 mRNA expression were inversely correlated in DLBCL patients. In representative DLBCL cell lines exposed to doxorubicin, the cells highly expressing BCL-2 were resistant, while the ones highly expressing BECLIN-1 were sensitive, and this correlated with low and high autophagy flux, respectively. Venetoclax targeting of BCL-2 increased while the spautin-1-mediated inhibition of BECLIN-1-dependent autophagy reversed doxorubicin sensitivity in the former and in the latter, respectively. By interrogating the TCGA DLBCL dataset, we found that BCL2 and BECN1 acted as negative and positive prognostic markers for DLBCL, respectively. The differentially expressed gene analysis in the respective cohorts revealed that BCL2 positively correlated with oncogenic pathways (e.g., glucose transport, HIF1A signaling, JAK-STAT signaling, PI3K-AKT-mTOR pathway) and negatively correlated with autophagy-related transcripts, while BECN1 showed the opposite trend. Notably, patients with high BECN1 expression displayed longer survival. Our data reveal, for the first time, that the modulation of BECLIN-1-dependent autophagy influences the prognosis of DLBCL patients and provide a mechanistic explanation supporting the therapeutic use of drugs that, by stimulating autophagy, can sensitize lymphoma cells to chemotherapy.

MicroRNAs as the critical regulators of autophagy-mediated cisplatin response in tumor cells

Chemotherapy is one of the most common therapeutic methods in advanced and metastatic tumors. Cisplatin (CDDP) is considered as one of the main first-line chemotherapy drugs in solid tumors. However, there is a high rate of CDDP resistance in cancer patients. Multi-drug resistance (MDR) as one of the main therapeutic challenges in cancer patients is associated with various cellular processes such as drug efflux, DNA repair, and autophagy. Autophagy is a cellular mechanism that protects the tumor cells toward the chemotherapeutic drugs. Therefore, autophagy regulatory factors can increase or decrease the chemotherapy response in tumor cells. MicroRNAs (miRNAs) have a pivotal role in regulation of autophagy in normal and tumor cells. Therefore, in the present review, we discussed the role of miRNAs in CDDP response through the regulation of autophagy. It has been reported that miRNAs mainly increased the CDDP sensitivity in tumor cells by inhibition of autophagy. PI3K/AKT signaling pathway and autophagy-related genes (ATGs) were the main targets of miRNAs in the regulation of autophagy-mediated CDDP response in tumor cells. This review can be an effective step to introduce the miRNAs as efficient therapeutic options to increase autophagy-mediated CDDP sensitivity in tumor cells.

Natural Compounds Targeting the Autophagy Pathway in the Treatment of Colorectal Cancer

Autophagy is a highly conserved intracellular degradation pathway by which misfolded proteins or damaged organelles are delivered in a double-membrane vacuolar vesicle and finally degraded by lysosomes. The risk of colorectal cancer (CRC) is high, and there is growing evidence that autophagy plays a critical role in regulating the initiation and metastasis of CRC; however, whether autophagy promotes or suppresses tumor progression is still controversial. Many natural compounds have been reported to exert anticancer effects or enhance current clinical therapies by modulating autophagy. Here, we discuss recent advancements in the molecular mechanisms of autophagy in regulating CRC. We also highlight the research on natural compounds that are particularly promising autophagy modulators for CRC treatment with clinical evidence. Overall, this review illustrates the importance of autophagy in CRC and provides perspectives for these natural autophagy regulators as new therapeutic candidates for CRC drug development.

SYP-3343 drives abnormal vascularization in zebrafish through regulating endothelial cell behavior

SYP-3343 is a novel strobilurin fungicide with excellent and broad-spectrum antifungal activity, and its potential toxicity raises public health concerns. However, the vascular toxicity of SYP-3343 to zebrafish embryos is still not well understood. In the present study, we investigated the effects of SYP-3343 on vascular growth and its potential mechanism of action. SYP-3343 inhibited zebrafish endothelial cell (zEC) migration, altered nuclear morphology, and triggered abnormal vasculogenesis and zEC sprouting angiogenesis, resulting in angiodysplasia. RNA sequencing showed that SYP-3343 exposure altered the transcriptional levels of vascular development-related biological processes in zebrafish embryos including angiogenesis, sprouting angiogenesis, blood vessel morphogenesis, blood vessel development, and vasculature development. Whereas, the addition of NAC exerted an improvement effect on zebrafish vascular defects owing to SYP-3343 exposure. Additionally, SYP-3343 altered cell cytoskeleton and morphology, obstructed migration and viability, disrupted cell cycle progression, and depolarized mitochondrial membrane potential, as well as promoted apoptosis and reactive oxygen species (ROS) in HUVEC. SYP-3343 also caused an imbalance of the oxidation and antioxidant systems and irritated the alterations in the cell cycle- and apoptosis-related genes in HUVECs. Collectively, SYP-3343 has high cytotoxicity, possibly by up-regulating p53 and caspase3 expressions and bax/bcl-2 ratio via ROS, leading to malformed vascular development.

Impaired Autophagy in Krabbe Disease: The Role of BCL2 and Beclin-1 Phosphorylation

Autophagic impairment was identified in many lysosomal storage diseases and adult neurodegenerative diseases. It seems that this defect could be directly related to the appearance of a neurodegenerative phenotype and could contribute to worsen metabolite accumulation and lysosomal distress. Thus, autophagy is becoming a promising target for supportive therapies. Autophagy alterations were recently identified also in Krabbe disease. Krabbe disease is characterized by extensive demyelination and dysmyelination and it is due to the genetic loss of function of the lysosomal enzyme galactocerebrosidase (GALC). This enzyme leads to the accumulation of galactosylceramide, psychosine, and secondary substrates such as lactosylceramide. In this paper, we induced autophagy through starvation and examined the cellular response occurring in fibroblasts isolated from patients. We demonstrated that the inhibitory AKT-mediated phosphorylation of beclin-1 and the BCL2-beclin-1 complex concur to reduce autophagosomes formation in response to starvation. These events were not dependent on the accumulation of psychosine, which was previously identified as a possible player in autophagic impairment in Krabbe disease. We believe that these data could better elucidate the capability of response to autophagic stimuli in Krabbe disease, in order to identify possible molecules able to stimulate the process.

Deubiquitylase PSMD14 inhibits autophagy to promote ovarian cancer progression via stabilization of LRPPRC

Autophagy is a key cellular process, which exists in many tumors and plays dual roles in tumor promotion and suppression. However, the role and mechanism of aberrant autophagy in ovarian cancer remains unclear. Ubiquitin-proteasome pathway is the most important pathway for specific protein degradation. Deubiquitinases (DUBs) have crucial roles in all the stages of tumorigenesis and progression. Herein, we explore the DUBs which contribute to aberrant autophagy in ovarian cancer. TCGA data analysis shows that the autophagy level is suppressed, and the selective autophagy receptor SQSTM1/p62 is abnormally high expressed in ovarian cancer. We screen and identify that the deubiquitinase PSMD14 negatively regulates autophagy level. Functional studies show that increased PSMD14 expression remarkably enhances ovarian cancer cells malignancy, whereas knockdown of PSMD14 has the opposite effect. Furthermore, in vivo assays show that knockdown of PSMD14 inhibits the growth, lung and abdominal metastasis of ovarian cancer. Mechanistically, PSMD14 directly interacts with LRPPRC and inhibits its ubiquitination, thereby inhibiting autophagy through LRPPRC/Beclin1-Bcl-2/SQSTM1 signaling pathway. Next, we demonstrate that PSMD14 is upregulated in ovarian cancer and high expression of PSMD14 positively correlates with LRPPRC. Taken together, we clarify the role of autophagy in regulating the ovarian cancer phenotype and provide insights into regulatory mechanism of autophagy in ovarian cancer.

The telomeric protein TERF2/TRF2 impairs HMGB1-driven autophagy

TERF2/TRF2 is a pleiotropic telomeric protein that plays a crucial role in tumor formation and progression through several telomere-dependent and -independent mechanisms. Here, we uncovered a novel function for this protein in regulating the macroautophagic/autophagic process upon different stimuli. By using both biochemical and cell biology approaches, we found that TERF2 binds to the non-histone chromatin-associated protein HMGB1, and this interaction is functional to the nuclear/cytoplasmic protein localization. Specifically, silencing of TERF2 alters the redox status of the cells, further exacerbated upon EBSS nutrient starvation, promoting the cytosolic translocation and the autophagic activity of HMGB1. Conversely, overexpression of wild-type TERF2, but not the mutant unable to bind HMGB1, negatively affects the cytosolic translocation of HMGB1, counteracting the stimulatory effect of EBSS starvation. Moreover, genetic depletion of HMGB1 or treatment with inflachromene, a specific inhibitor of its cytosolic translocation, completely abolished the pro-autophagic activity of TERF2 silencing. In conclusion, our data highlighted a novel mechanism through which TERF2 modulates the autophagic process, thus demonstrating the key role of the telomeric protein in regulating a process that is fundamental, under both physiological and pathological conditions, in defining the fate of the cells.Abbreviations: ALs: autolysosomes; ALT: alternative lengthening of telomeres; ATG: autophagy related; ATM: ATM serine/threonine kinase; CQ: Chloroquine; DCFDA: 2',7'-dichlorofluorescein diacetate; DDR: DNA damage response; DHE: dihydroethidium; EBSS: Earle's balanced salt solution; FACS: fluorescence-activated cell sorting; GFP: green fluorescent protein; EGFP: enhanced green fluorescent protein; GSH: reduced glutathione; GSSG: oxidized glutathione; HMGB1: high mobility group box 1; ICM: inflachromene; IF: immunofluorescence; IP: immunoprecipitation; NAC: N-acetyl-L-cysteine; NHEJ: non-homologous end joining; PLA: proximity ligation assay; RFP: red fluorescent protein; ROS: reactive oxygen species; TIF: telomere-induced foci; TERF2/TRF2: telomeric repeat binding factor 2.

Codelivery of HBx-siRNA and Plasmid Encoding IL-12 for Inhibition of Hepatitis B Virus and Reactivation of Antiviral Immunity

Chronic hepatitis B is a critical cause of many serious liver diseases such as hepatocellular carcinoma (HCC). The main challenges in hepatitis B treatment include the rebound of hepatitis B virus (HBV)-related antigen levels after drug withdrawal and the immunosuppression caused by the virus. Herein, we demonstrate that the HBV-related antigen can be effectively inhibited and antiviral immunity can be successfully reactivated through codelivery of the small interfering RNA (siRNA) targeting HBV X protein (HBx) and the plasmid encoding interleukin 12 (pIL-12) to hepatocytes and immune cells. After being treated by the siRNA/pIL-12 codelivery system, HBx mRNA and hepatitis B surface antigen (HBsAg) are dramatically reduced in HepG2.215 cells. More importantly, the downregulated CD47 and programmed death ligand 1 (PD-L1) and the upregulated interferon-β promoter stimulator-1 (IPS-1), retinoic acid-inducible gene-1 (RIG-1), CD80, and human leukocyte antigen-1 (HLA-1) in treated HepG2.215 cells indicate that the immunosuppression is reversed by the codelivery system. Furthermore, the codelivery system results in inhibition of extracellular regulated protein kinases (ERK) and phosphoinositide-3-kinase (PI3K)/protein kinase B (Akt) pathways, as well as downregulation of B-cell lymphoma-2 (Bcl-2) and upregulation of p53, implying its potential in preventing the progression of HBV-induced HCC. In addition, J774A.1 macrophages treated by the codelivery system were successfully differentiated into the M1 phenotype and expressed enhanced cytokines with anti-hepatitis B effects such as interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α). Therefore, we believe that codelivery of siRNA and pIL-12 can effectively inhibit hepatitis B virus, reverse virus-induced immunosuppression, reactivate antiviral immunity, and hinder the progression of HBV-induced hepatocellular carcinoma. This investigation provides a promising approach for the synergistic treatment of HBV infection.

Alisol B 23-Acetate Increases the Antitumor Effect of Bufalin on Liver Cancer through Inactivating Wnt/β-Catenin Axis

Objective

Liver cancer seriously threatens the health of people. Meanwhile, it has been reported that bufalin could act as an inhibitor in liver cancer. In addition, alisol B 23-acetate is a natural product derived from Alisma plantago-aquatica Linn which has an antitumor effect. In this study, we aimed to explore whether alisol B 23-acetate could increase the antitumor effect of bufalin on liver cancer.

Methods

In order to detect the effect of alisol B 23-acetate in combination with bufalin on liver cancer, human liver cancer SMMC-7721 and MHCC97 cells were used as subjects. Bufalin and alisol B 23-acetate were performed on cells. Cell viability was tested by MTT assay. In addition, flow cytometry was performed to assess the cell apoptosis. Autophagy-related protein levels were tested by western blotting.

Results

The data revealed that bufalin significantly decreased the viability of liver cancer cells, and the inhibitory effect was further increased by alisol B 23-acetate. In addition, alisol B 23-acetate notably enhanced the apoptotic effect of bufalin on liver cancer cells through mediation of Mcl-1, Bax, Bcl-2, and cleaved caspase-3. Meanwhile, alisol B 23-acetate in combination with bufalin induced the autophagy in liver cancer cells through mediation of Beclin-1 and p62. Furthermore, alisol B 23-acetate in combination with bufalin significantly downregulated the level of GSK-3β and increased the expression of β-catenin in liver cancer cells.

Conclusion

In summary, these findings provide the first evidence that alisol B 23-acetate improves the anticancer activity of bufalin on liver cancer through activation of the Wnt/β-catenin axis, and these outcomes might shed new lights on exploring the new methods against liver cancer.

TRIM65 Promotes Cervical Cancer Through Selectively Degrading p53-Mediated Inhibition of Autophagy and Apoptosis

Tripartite motif containing 65 (TRIM65) is an E3 ubiquitin ligase that has been implicated in a variety of cellular processes as well as tumor progression, but its biological role and the underlying mechanism in cervical cancer is unclear. Here, we reported that TRIM65 expression in human cervical cancer tissues was significantly higher than that in the adjacent normal cervical tissues, and TRIM65 knockdown enhanced autophagic flux and cell apoptosis, but not cell cycle, to dramatically inhibit the proliferation and migration of cervical cancer cells. Furthermore, our experiments showed that TRIM65 exhibited oncogenic activities via directly targeting p53, a tumor suppressor and a common upsteam regulator between autophagy and apoptosis, promoting ubiquitination and proteasomal degradation of p53. Taken together, our studies demonstrated that TRIM65 knockdown promotes cervical cancer cell death through enhancing autophagy and apoptosis, suggesting that TRIM65 may be a potential therapeutic target for cervical cancer clinically.

The molecular regulation of autophagy in antimicrobial immunity

Autophagy is a catabolic process that can degrade worn-out organelles and invading pathogens. The activation of autophagy regulates innate and adaptive immunity, playing a key role in the response to microbial invasion. Microbial infection may cause different consequences such as the elimination of invaders through autophagy or xenophagy, host cell death, and symbiotic relationships. Pathogens adapt to the autophagy mechanism and further relieve intracellular stress, which is conducive to host cell survival and microbial growth. The regulation of autophagy forms a complex network through which host immunity is modulated, resulting in a variety of pathophysiological manifestations. Modification of the autophagic pathway is an essential target for the development of antimicrobial drugs.

TERT Promoter Revertant Mutation Inhibits Melanoma Growth through Intrinsic Apoptosis

Simple Summary

TERT -146 C>T frequently occurs in many cancer cells. Research targeting the telomerase reverse transcriptase (TERT) promoter contributes to a better understanding of cancer development and treatment. Many conventional cancer treatments aim to develop new drugs targeting TERT. Here, for TERT -146 we converted T to C. The proliferation, migration and invasion of melanoma cells in vitro, and the growth of the tumor in vivo were inhibited. Moreover, the downregulated protein expression of B-cell lymphoma 2 (Bcl-2) indicated that the TERT promoter revertant mutation abrogated the inhibitory effect of mutant TERT on apoptosis. These data elucidated the relationship between the TERT promoter revertant mutations and apoptosis for the first time, and also implied that TERT -146 may be a causal mutation of melanoma. This study provides a new insight into the TERT promoter revertant mutations and apoptosis. The TERT promoter provides preliminary validation of the potential tumor treatment.

Abstract

Human telomerase is a specialized DNA polymerase whose catalytic core includes both TERT and human telomerase RNA (hTR). Telomerase in humans, which is silent in most somatic cells, is activated to maintain the telomere length (TEL) in various types of cancer cells, including melanoma. In the vast majority of tumor cells, the TERT promoter is mutated to promote proliferation and inhibit apoptosis. Here, we exploited NG-ABEmax to revert TERT -146 T to -146 C in melanoma, and successfully obtained TERT promoter revertant mutant cells. These TERT revertant mutant cells exhibited significant growth inhibition both in vitro and in vivo. Moreover, A375^−146C/C cells exhibited telomere shortening and the downregulation of TERT at both the transcription and protein levels, and migration and invasion were inhibited. In addition, TERT promoter revertant mutation abrogated the inhibitory effect of mutant TERT on apoptosis via B-cell lymphoma 2 (Bcl-2), ultimately leading to cell death. Collectively, the results of our work demonstrate that reverting mutations in the TERT promoter is a potential therapeutic option for melanoma.

Treatment With Glycogen Synthase Kinase 3β Inhibitor Decreases Apoptotic and Autophagic Reactions in Rat Rotator Cuff Tears

Background:

Apoptosis and autophagy are known to be correlated with the extent of damage in torn rotator cuffs, and there is no biological evidence for self-recovery or healing of the rotator cuff tear.

Purpose:

To establish in a rat model of partial- and full-thickness rotator cuff tears how a glycogen synthase kinase 3β (GSK-3β) inhibitor affects the expression of apoptotic and autophagic markers.

Study Design:

Controlled laboratory study.

Methods:

Twelve-week-old Sprague Dawley rats were divided into 3 groups (n = 16 per group). Group 1 acted as the control, with no treatment; group 2 received partial-thickness (right side) and full-thickness (left side) rotator cuff tears only; and group 3 received the same rotator cuff injuries, with GSK-3β inhibitor injected afterward. The tendons from each group were harvested 42 days after surgery. Evaluation of gene expression, immunohistochemistry, and TUNEL staining (terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling) were performed for the following markers: caspases 3, 8, and 9 as well as Bcl-2 (B-cell lymphoma 2); BAX (Bcl-2-associated X protein); beclin 1; p53; and GSK-3β; which represented apoptotic and autophagic reactions. Statistical analysis was performed using 1-way analysis of variance.

Results:

In the group 2 rats with partial- and full-thickness tears, there were significant increases in the mRNA levels (fold changes) of all 8 markers as compared with group 1 (control). All these increased markers showed significant downregulation by the GSK-3β inhibitor in partial-thickness tears. However, the response to the GSK-3β inhibitor in full-thickness tears was not as prominent as in partial-thickness tears. The number of TUNEL-positive cells in group 2 (partial, 35.08% ± 1.625% [mean ± SE]; full, 46.92% ± 1.319%) was significantly higher than in group 1 (18.02% ± 1.036%; P < .01) and group 3 (partial, 28.04% ± 2.607% [P < .01]; full, 38.97% ± 2.772% [P < .01]), and immunohistochemistry revealed increased expression of all the markers in group 2 as compared with control.

Conclusion:

The apoptotic and autophagic activity induced in a rat model of an acute rotator cuff tear was downregulated after treatment with a GSK-3β inhibitor, particularly with partial-thickness rotator cuff tears.

Clinical Relevance:

A GSK-3β inhibitor may be able to modulate deterioration in a torn rotator cuff.

Molecular Effectors of Photodynamic Therapy-Mediated Resistance to Cancer Cells

Photodynamic therapy (PDT) is currently enjoying considerable attention as the subject of experimental research to treat resistant cancers. The preferential accumulation of a non-toxic photosensitizer (PS) in different cellular organelles that causes oxidative damage by combining light and molecular oxygen leads to selective cell killing. However, one major setback, common among other treatment approaches, is tumor relapse and the development of resistance causing treatment failure. PDT-mediated resistance could result from increased drug efflux and decreased localization of PS, reduced light exposure, increased DNA damage repair, and altered expression of survival genes. This review highlights the essential insights of PDT reports in which PDT resistance was observed and which identified some of the molecular effectors that facilitate the development of PDT resistance. We also discuss different perceptions of PDT and how its current limitations can be overturned to design improved cancer resistant treatments.

LncRNA OTUD6B-AS1 promotes paclitaxel resistance in triple negative breast cancer by regulation of miR-26a-5p/MTDH pathway-mediated autophagy and genomic instability

Genomic instability (GIN) is pivotal in regulating tumor drug resistance, which blocked the treatment of triple negative breast cancer (TNBC). Although recent studies implied that non-coding RNA (ncRNA)-mediated autophagy abolishment promoted tumorigenesis by up-regulation of GIN, autophagy was known as a risk factor in tumor drug resistance. However, previous study also pointed that up-regulation of autophagy promoted GIN. Therefore, the relationship between autophagy and GIN is not clear, and more work is needed. And, if an ncRNA is identified to be a co-regulator of autophagy and GIN, it will be a potential therapy target of chemotherapy resistance in TNBC. In our study, we recognized both autophagy-GIN-associated microRNA (mi-26a-5p) by big data analysis, which was prognosis-correlated in breast cancer. Next, we identified the up-stream regulators (long non-coding RNA, lncRNA) and down-stream targets of miR-26a-5p by bioinformatics analysis (online public databases). Finally, we established lncRNA OTUD6B-AS1/miR-26a-5p/MTDH signaling pathway, and verified their functions by cytological, molecular biological and zoological experiments. In general, our study found (1) miR-26a-5p was a protective factor of breast cancer, while OTUD6B-AS1 and MTDH were risk factors; (2) OTUD6B-AS1 was the up-stream regulator of miR-26a-5p verified by luciferase; (3) up-regulation of miR-26a-5p and down-regulation of MTDH promoted cellular cytotoxicity of paclitaxel (PTX) in vitro and in vivo. (4) down-regulation of miR-26a-5p, overexpression of MTDH and OTUD6B-AS1 promoted autophagy and DNA damage; (5) up-regulation of OTUD6B-AS1 and MTDH inhibited DNA damage response (DDR) by inhibiting the phosphorylated activation of RAD51, ATR and ATM.

Mechanism Involved in Fortification by Berberine in CDDP-Induced Nephrotoxicity

BACKGROUND

The activation of Nrf2/HO-1 pathway has been shown to protect against cisplatin- induced nephrotoxicity by reducing oxidative stress. Berberine (Ber), an isoquinoline alkaloid, has demonstrated antioxidant, anti-inflammatory and anti-apoptotic activities in various experimental models.

AIM

To check the effect of Ber on cisplatin-induced nephrotoxicity and to explore the involved mechanism.

METHODS

Adult male Wistar rats were divided into 6 groups: Normal, cisplatin-control, treatment groups and per se group. Normal saline and Ber (20, 40 and 80 mg/kg; p.o.) was administered to rats for 10 days. A single intraperitoneal injection of cisplatin (8 mg/kg) was injected on 7th day to induced nephrotoxicity. On 10th day, rats were sacrificed, the kidney was removed and stored for the estimation of various parameters.

RESULTS

As compared to cisplatin-control group, Ber pretreatment improved renal function system and preserved renal architecture. It also diminished oxidative stress by upregulating the expression of Nrf2/HO-1 proteins. In addition, Ber attenuated the cisplatin mediated inflammation and apoptosis. Furthermore, it also reduced the phosphorylation of p38/JNK and PARP/Beclin-1 expression in the kidney.

CONCLUSION

Ber attenuated renal injury by activating Nrf2/HO-1 and inhibiting JNK/p38MAPKs/ PARP/Beclin-1 expression which prevented oxidative stress, inflammation, apoptosis and autophagy in renal tissue.

Circular RNAs in Lung Cancer: Recent Advances and Future Perspectives

Globally, lung cancer is the most commonly diagnosed cancer and carries with it the greatest mortality rate, with 5-year survival rates varying from 4–17% depending on stage and geographical differences. For decades, researchers have studied disease mechanisms, occurrence rates and disease development, however, the mechanisms underlying disease progression are not yet fully elucidated, thus an increased understanding of disease pathogenesis is key to developing new strategies towards specific disease diagnoses and targeted treatments. Circular RNAs (circRNAs) are a class of non-coding RNA widely expressed in eukaryotic cells, and participate in various biological processes implicated in human disease. Recent studies have indicated that circRNAs both positively and negatively regulate lung cancer cell proliferation, migration, invasion and apoptosis. Additionally, circRNAs could be promising biomarkers and targets for lung cancer therapies. This review systematically highlights recent advances in circRNA regulatory roles in lung cancer, and sheds light on their use as potential biomarkers and treatment targets for this disease.

A functional outside-in signaling network of proteoglycans and matrix molecules regulating autophagy

Proteoglycans and selected extracellular matrix constituents are emerging as intrinsic and critical regulators of evolutionarily conversed, intracellular catabolic pathways. Often, these secreted molecules evoke sustained autophagy in a variety of cell types, tissues, and model systems. The unique properties of proteoglycans have ushered in a paradigmatic shift to broaden our understanding of matrix-mediated signaling cascades. The dynamic cellular pathway controlling autophagy is now linked to an equally dynamic and fluid signaling network embedded in a complex meshwork of matrix molecules. A rapidly emerging field of research encompasses multiple matrix-derived candidates, representing a menagerie of soluble matrix constituents including decorin, biglycan, endorepellin, endostatin, collagen VI and plasminogen kringle 5. These matrix constituents are pro-autophagic and simultaneously anti-angiogenic. In contrast, perlecan, laminin α2 chain, and lumican have anti-autophagic functions. Mechanistically, each matrix constituent linked to intracellular catabolic events engages a specific cell surface receptor that often converges on a common core of the autophagic machinery including AMPK, Peg3 and Beclin 1. We consider this matrix-evoked autophagy as non-canonical given that it occurs in an allosteric manner and is independent of nutrient availability or prevailing bioenergetics control. We propose that matrix-regulated autophagy is an important outside-in signaling mechanism for proper tissue homeostasis that could be therapeutically leveraged to combat a variety of diseases.

MiR-140-3p Impedes Gastric Cancer Progression and Metastasis by Regulating BCL2/BECN1-Mediated Autophagy

Introduction

MiRNAs have been proven to modulate the progression of gastric cancer (GC). In this field, we evaluated the role and mechanism of miR-140-3p in GC.

Methods

Western blotting and qRT-PCR were used to detect the levels of miR-140-3p and BCL2. The interaction of miR-140-3p and BCL2 was confirmed by dual-luciferase reporter and miRNA pull-down assays. CCK-8, EdU, wound healing, and Transwell invasion assays were performed to evaluate cell proliferation, migration and invasion. Autophagy was analyzed using Western blot analysis of the LC3-II/I ratio and immunofluorescence staining. A xenograft model was established to reveal the role of miR-140-3p in tumorigenesis.

Results

In GC cell lines and tissues, miR-140-3p was highly expressed, and BCL2 was expressed at low levels. MiR-140-3p directly inhibited BCL2 expression and indirectly promoted BECN1 expression, and BCL2 inhibited BECN1 expression. MiR-140-3p overexpression or silencing restrained or facilitated migration, invasion and EMT in GC cells. Moreover, we noticed that overexpression or downregulation of miR-140-3p promoted or suppressed BECN1-dependent autophagy in GC cells. BCL2 introduction or BECN1 silencing in GC cells partially blocked the effects of miR-140-3p. In conclusion, miR-140-3p directly downregulated the expression of BCL2, BCL2 downregulation further activated BECN1-dependent autophagy, and autophagy activation further inhibited EMT.

Conclusion

miR-140-3p may act as a tumor suppressor by targeting BCL2 and regulating downstream BECN1-induced autophagy and metastasis in GC progression.

Repurposing of FDA-approved drugs as autophagy inhibitors in tumor cells

Autophagy and apoptosis are the two crucial processes of programmed cell death found in all eukaryotic cells; however, the elevated physiological stress in the tumor microenvironment leads to uncontrolled up-regulation in the process of autophagy. Available literatures suggest that inhibiting up-regulated autophagy in the cancerous cells may lead to the apoptosis and thereby culminate to tumor clearance. Several studies have been performed to design autophagy-inhibitors using either Beclin-1 or Bcl-2 as a target in isolation. However, to overcome the constraints of the availability of small and potent autophagy inhibitors, we have attempted extensive computational approach of repurposing the FDA-approved drugs from the ZINC database in order to inhibit the interaction between the Beclin1 and Bcl-2. Out of 1565 FDA-approved drugs used in our computational work, we sorted the drugs Ponatinib, Simeprevir, and Nilotinib through various methods viz. molecular docking, Lipinski's filter, MD simulation and MM/PBSA, and we found these aforementioned drugs to show good binding energy and favorable interaction with the BH3 domain of Beclin1. We anticipate from our computational results that these drugs may become potent candidates to inhibit autophagy and exhibit the apoptosis in the tumor microenvironment and combat the current limitation of potent autophagy inhibitors; however, to substantiate our in-silico results, further experimental validations of these drug molecules are currently in progress.Communicated by Ramaswamy H. Sarma.

Role of Bcl-2 Family Proteins in Photodynamic Therapy Mediated Cell Survival and Regulation

Photodynamic therapy (PDT) is a treatment modality that involves three components: combination of a photosensitizer, light and molecular oxygen that leads to localized formation of reactive oxygen species (ROS). The ROS generated from this promising therapeutic modality can be lethal to the cell and leads to consequential destruction of tumor cells. However, sometimes the ROS trigger a stress response survival mechanism that helps the cells to cope with PDT-induced damage, resulting in resistance to the treatment. One preferred mechanism of cell death induced by PDT is apoptosis, and B-cell lymphoma 2 (Bcl-2) family proteins have been described as a major determinant of life or death decision of the death pathways. Apoptosis is a cellular self-destruction mechanism to remove old cells through the biological event of tissue homeostasis. The Bcl-2 family proteins act as a critical mediator of a life–death decision of cells in maintaining tissue homeostasis. There are several reports that show cancer cells developing resistance due to the increased interaction of the pro-survival Bcl-2 family proteins. However, the key mechanisms leading to apoptosis evasion and drug resistance have not been adequately understood. Therefore, it is critical to understand the mechanisms of PDT resistance, as well as the Bcl-2 family proteins, to give more insight into the treatment outcomes. In this review, we describe the role of Bcl-2 gene family proteins’ interaction in response to disease progression and PDT-induced resistance mechanisms.

Proteoglycan-driven Autophagy: A Nutrient-independent Mechanism to Control Intracellular Catabolism

Proteoglycans are rapidly emerging as versatile regulators of intracellular catabolic pathways. This is predominantly achieved via the non-canonical induction of autophagy, a fundamentally and evolutionarily conserved eukaryotic pathway necessary for maintaining organismal homeostasis. Autophagy facilitated by either decorin, a small leucine-rich proteoglycan, or perlecan, a basement membrane heparan sulfate proteoglycan, proceeds independently of ambient nutrient conditions. We found that soluble decorin evokes endothelial cell autophagy and breast carcinoma cell mitophagy by directly interacting with vascular endothelial growth factor receptor 2 (VEGFR2) or the Met receptor tyrosine kinase, respectively. Endorepellin, a soluble, proteolytic fragment of perlecan, induces autophagy and endoplasmic reticulum stress within the vasculature, downstream of VEGFR2. These potent matrix-derived cues transduce key biological information via receptor binding to converge upon a newly discovered nexus of core autophagic machinery comprised of Peg3 (paternally expressed gene 3) for autophagy or mitostatin for mitophagy. Here, we give a mechanistic overview of the nutrient-independent, proteoglycan-driven programs utilized for autophagic or mitophagic progression. We propose that catabolic control of cell behavior is an underlying basis for proteoglycan versatility and may provide novel therapeutic targets for the treatment of human disease.

The role of cell signaling in the crosstalk between autophagy and apoptosis in the regulation of tumor cell survival in response to sorafenib and neratinib

The molecular mechanisms by which tumor cells survive or die following therapeutic interventions are complex. There are three broadly defined categories of cell death processes: apoptosis (Type I), autophagic cell death (Type II), and necrosis (Type III). In hematopoietic tumor cells, the majority of toxic stimuli cause these cells to undergo a death process called apoptosis; apoptosis specifically involves the cleavage of DNA into large defined pieces and their subsequent localization in vesicles. Thus, 'pure' apoptosis largely lacks inflammatory potential. In carcinomas, however, the mechanisms by which tumor cells ultimately die are considerably more complex. Although the machinery of apoptosis is engaged by toxic stimuli, other processes such as autophagy ("self-eating") and replicative cell death can lead to observations that do not simplistically correspond to any of the individual Type I-III formalized death categories. The 'hybrid' forms of cell death observed in carcinoma cells result in cellular materials being released into the extracellular space without packaging, which promotes inflammation, potentially leading to the accelerated re-growth of surviving tumor cells by macrophages. Drugs as single agents or in combinations can simultaneously initiate signaling via both apoptotic and autophagic pathways. Based on the tumor type and its oncogene drivers, as well as the drug(s) being used and the duration and intensity of the autophagosome signal, apoptosis and autophagy have the potential to act in concert to kill or alternatively that the actions of either pathway can act to suppress signaling by the other pathway. And, there also is evidence that autophagic flux, by causing lysosomal protease activation, with their subsequent release into the cytosol, can directly mediate killing. This review will discuss the interactive biology between apoptosis and autophagy in carcinoma cells. Finally, the molecular actions of the FDA-approved drugs neratinib and sorafenib, and how they enhance both apoptotic and toxic autophagic processes, alone or in combination with other agents, is discussed in a bench-to-bedside manner.

Decorin in the Tumor Microenvironment

The tumor microenvironment plays a determining role in cancer development through a plethora of interactions between the extracellular matrix and tumor cells. Decorin is a prototype member of the SLRP family found in a variety of tissues and is expressed in the stroma of various forms of cancer. Decorin has gained recognition for its essential roles in inflammation, fibrotic disorders, and cancer, and due to its antitumor properties, it has been proposed to act as a "guardian from the matrix." Initially identified as a natural inhibitor of transforming growth factor-β, soluble decorin is emerging as a pan-RTK inhibitor targeting a multitude of RTKs, including EGFR, Met, IGF-IR, VEGFR2, and PDGFR. Besides initiating signaling, decorin/RTK interaction can induce caveosomal internalization and receptor degradation. Decorin also triggers cell cycle arrest and apoptosis and evokes antimetastatic and antiangiogenic processes. In addition, as a novel regulatory mechanism, decorin was shown to induce conserved catabolic processes, such as endothelial cell autophagy and tumor cell mitophagy. Therefore, decorin is a promising candidate for combatting cancer, especially the cancer types heavily dependent on RTK signaling.

Disulfiram potentiates docetaxel cytotoxicity in breast cancer cells through enhanced ROS and autophagy

BACKGROUND

Recent studies have demonstrated that autophagy plays a critical role in reducing the drug sensitivity of docetaxel (DTX) therapy. Disulfiram (DSF) has exhibited potent autophagy inducing activity in multiple studies. We hypothesized that DSF co-treatment could sensitize breast cancer cells to DTX therapy via autophagy modulation.

METHODS

Breast cancer cells, MCF7, and 4T1, were treated with DTX and DSF, alone and in combination. The effects were analyzed by evaluating cytotoxicity, induction of apoptosis, induction of autophagy, and reactive oxygen species (ROS) generation. In addition, the consequence of autophagy and ROS inhibition on the DTX + DSF mediated cytotoxicity was also evaluated.

RESULTS

Significant synergism in cytotoxicity was observed with DTX + DSF combination in breast cancer cells, MCF7, and 4T1. Hyper induction of ROS and autophagy was also found with the combination treatment. ROS inhibition by N-Acetyl Cysteine (NAC), as well as autophagy inhibition by ATG5 silencing significantly reduced the autophagy level as well as cytotoxicity of the DTX + DSF combination, indicating that the induction of autophagy mediated by high ROS generation played a critical role behind the synergistic cytotoxicity.

CONCLUSIONS

This study indicates that DTX + DSF combination therapy can effectively sensitize cancer cells by hyper inducing autophagy through ROS generation and can be developed as a therapeutic strategy for cancer treatment in the future.

Oncogenic BRAF, endoplasmic reticulum stress, and autophagy: Crosstalk and therapeutic targets in cutaneous melanoma

BRAF is a member of the RAF family of serine/threonine-specific protein kinases. Oncogenic BRAF, in particular, BRAF V600E, can disturb the normal protein folding machinery in the endoplasmic reticulum (ER) leading to accumulation of unfolded/misfolded proteins in the ER lumen, a condition known as endoplasmic reticulum (ER) stress. To alleviate such conditions, ER-stressed cells have developed a highly robust and adaptable signaling network known as unfolded protein response (UPR). UPR is ordinarily a cytoprotective response and usually operates through the induction of autophagy, an intracellular lysosomal degradation pathway that directs damaged proteins, protein aggregates, and damaged organelles for bulk degradation and recycling. Both ER stress and autophagy are involved in the progression and chemoresistance of melanoma. Melanoma, which arises as a result of malignant transformation of melanocytes, exhibits exceptionally high therapeutic resistance. Many mechanisms of therapeutic resistance have been identified in individual melanoma patients and in preclinical BRAF-driven melanoma models. Recently, it has been recognized that oncogenic BRAF interacts with GRP78 and removes its inhibitory influence on the three fundamental ER stress sensors of UPR, PERK, IRE1α, and ATF6. Dissociation of GRP78 from these ER stress sensors prompts UPR that subsequently activates cytoprotective autophagy. Thus, pharmacological inhibition of BRAF-induced ER stress-mediated autophagy can potentially resensitize BRAF mutant melanoma tumors to apoptosis. However, the underlying molecular mechanism of how oncogenic BRAF elevates the basal level of ER stress-mediated autophagy in melanoma tumors is not well characterized. A better understanding of the crosstalk between oncogenic BRAF, ER stress and autophagy may provide a rationale for improving existing cancer therapies and identify novel targets for therapeutic intervention of melanoma.

Progressive lysosomal membrane permeabilization induced by iron oxide nanoparticles drives hepatic cell autophagy and apoptosis

Iron oxide nanoparticles (IONs) are frequently used in various biomedical applications, in particular as magnetic resonance imaging contrast agents in liver imaging. Indeed, number of IONs have been withdrawn due to their poor clinical performance. Yet comprehensive understanding of their interactions with hepatocytes remains relatively limited. Here we investigated how iron oxide nanocubes (IO-cubes) and clusters of nanocubes (IO-clusters) affect distinct human hepatic cell lines. The viability of HepG2, Huh7 and Alexander cells was concentration-dependently decreased after exposure to either IO-cubes or IO-clusters. We found similar cytotoxicity levels in three cell lines triggered by both nanoparticle formulations. Our data indicate that different expression levels of Bcl-2 predispose cell death signaling mediated by nanoparticles. Both nanoparticles induced rather apoptosis than autophagy in HepG2. Contrary, IO-cubes and IO-clusters trigger distinct cell death signaling events in Alexander and Huh7 cells. Our data clarifies the mechanism by which cubic nanoparticles induce autophagic flux and the mechanism of subsequent toxicity. These findings imply that the cytotoxicity of ION-based contrast agents should be carefully considered, particularly in patients with liver diseases.

Antimicrobial, Antioxidant, and Anti-Tumor Activities of Sargassum linearifolium and Cystoseira crinita from Egyptian Mediterranean Coast

Brown algae earned importance by virtue of their promising secondary metabolites of reasonable biological activities. Herein, the antioxidant, antimicrobial, and anticancer effects of crude extracts obtained from two Egyptian brown seaweeds, Sargassum linearifolium and Cystoseira crinita were evaluated. Phytochemical and GC-MS analyses revealed numerous active secondary metabolites in C. crinita cold methanolic extract (CCME) and S. linearifolium hot aqueous extract (SHAE). Both SHAE and CCME exhibited comparable DPPH (124.5 vs 125.6 µg/ml) and ABTS (257.1 vs 254.8 µg/ml) scavenging activities, respectively. Moreover, both crude extracts exhibited antimicrobial activity against various pathogenic microorganisms. Interestingly, employing MTT assay revealed cytotoxic effects of both extracts against a panel of cancer cells, where CCME showed a strong cytotoxic activity against MCF-7 cells (IC50 = 18.0 ± 0.74 µg/ml), while SHAE exhibited a moderate effect (IC50 = 31.1 ± 1.04 µg/ml). Increased mRNA and protein expression of Bax and Beclin-1 as well as the decreased expression of Bcl-2 revealed the ability of both extracts to induce apoptosis and autophagy in MCF-7 cells. Collectively, these findings provide evidence for antioxidant, antimicrobial, as well as anticancer effects driven by the two brown seaweeds that may underlay their plausible application in the therapeutic uses.

Protein Kinase C Isozymes and Autophagy during Neurodegenerative Disease Progression

Protein kinase C (PKC) isozymes are members of the Serine/Threonine kinase family regulating cellular events following activation of membrane bound phospholipids. The breakdown of the downstream signaling pathways of PKC relates to several disease pathogeneses particularly neurodegeneration. PKC isozymes play a critical role in cell death and survival mechanisms, as well as autophagy. Numerous studies have reported that neurodegenerative disease formation is caused by failure of the autophagy mechanism. This review outlines PKC signaling in autophagy and neurodegenerative disease development and introduces some polyphenols as effectors of PKC isozymes for disease therapy.

Remote Actuation of Apoptosis in Liver Cancer Cells via Magneto-Mechanical Modulation of Iron Oxide Nanoparticles

Lysosome-activated apoptosis represents an alternative method of overcoming tumor resistance compared to traditional forms of treatment. Pulsed magnetic fields open a new avenue for controlled and targeted initiation of lysosomal permeabilization in cancer cells via mechanical actuation of magnetic nanomaterials. In this study we used a noninvasive tool; namely, a benchtop pulsed magnetic system, which enabled remote activation of apoptosis in liver cancer cells. The magnetic system we designed represents a platform that can be used in a wide range of biomedical applications. We show that liver cancer cells can be loaded with superparamagnetic iron oxide nanoparticles (SPIONs). SPIONs retained in lysosomal compartments can be effectively actuated with a high intensity (up to 8 T), short pulse width (~15 µs), pulsed magnetic field (PMF), resulting in lysosomal membrane permeabilization (LMP) in cancer cells. We revealed that SPION-loaded lysosomes undergo LMP by assessing an increase in the cytosolic activity of the lysosomal cathepsin B. The extent of cell death induced by LMP correlated with the accumulation of reactive oxygen species in cells. LMP was achieved for estimated forces of 700 pN and higher. Furthermore, we validated our approach on a three-dimensional cellular culture model to be able to mimic in vivo conditions. Overall, our results show that PMF treatment of SPION-loaded lysosomes can be utilized as a noninvasive tool to remotely induce apoptosis.

Magnoflorine improves sensitivity to doxorubicin (DOX) of breast cancer cells via inducing apoptosis and autophagy through AKT/mTOR and p38 signaling pathways

Breast cancer is a leading cause of cancer death among women worldwide. Doxorubicin (DOX) is a broad-spectrum anti-breast cancer agent, but its clinical use is restricted due to irreversible tissue toxicity. Thereby, new therapeutic approaches are urgently required to promote the sensitivity of breast cancer cells to DOX. Magnoflorine (Mag), a quaternary alkaloid isolated from Chinese herb Magnolia or Aristolochia, has various biological activities, such as anti-inflammation, anti-cancer, and anti-anxiety. In the study, we explored the effects Mag on the sensitivity of breast cancer cells to DOX. We demonstrated that Mag strongly promoted DOX-induced anti-proliferative effects in breast cancer cells while not in normal cells. Mag addition markedly promoted the effects of DOX on the inhibition of migration and invasion in breast cancer cells. DOX-triggered DNA damage in breast cancer cells was further accelerated by combination with Mag. DOX-induced cell distribution in G2/M phase was markedly elevated when co-treated with Mag. Additionally, DOX/Mag combinational treatment significantly induced apoptosis in breast cancer cells when compared to DOX alone group through inducing Caspase-3 cleavage. Moreover, Mag markedly promoted the role of DOX in autophagy induction by elevating light chain 3 (LC3)-II expression. Combination treatment with DOX and Mag significantly inhibited the activation of phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling, and promoted p38 mitogen-activated protein kinase (MAPK) pathway. In addition, treatment with wortmannin (Wor, a blocker of autophagosome formation) markedly reduced DOX/Mag-induced p38 MAPK activation and LC3 conversion in breast cancer cells. Further, in MCF-7 xenograft model, DOX combined with Mag displayed a significant anti-tumor effect with little toxicity to organs such as liver, heart, kidney and spleen. These findings suggested that Mag promoted the anti-cancer effects of DOX to induce cellular apoptosis and autophagy in breast cancer cells.

B-cell lymphoma-2-associated transcription factor 1 is overexpressed and contributes to sorafenib resistance in hepatocellular carcinoma

AIM

B-cell lymphoma-2-associated transcription factor 1 (BCLAF1) is involved in various biological processes including tumorigenesis, but its function and expression in hepatocellular carcinoma (HCC) is little known, and its clinical value in HCC has not yet been defined.

METHODS

The protein level of BCLAF1 in HCC specimens and paired adjacent normal tissues was examined by immunohistochemical staining. The effects of BCLAF1 on autophagy in HCC cells were detected by confocal microscopy, transmission electron microscopy, and western blot analysis. Cell proliferation and tumorigenicity assays were carried out in vitro and in vivo. Flow cytometry assay was used to determine the apoptosis level of HCC cells. The correlation of BCLAF1 and sorafenib resistance in HCC was analyzed by the Kaplan-Meier survival method.

RESULTS

High expression of BCLAF1 was found in HCC tissues compared with adjacent normal tissues, and higher BCLAF1 expression was correlated with higher tumor-node-metastasis stage, worse differentiation, and worse prognosis of HCC patients. BCLAF1 could induce autophagy in HCC cells in response to starvation and BCLAF1-mediated autophagy could enhance cell proliferation and impede cell apoptosis under stress conditions. Animal experiments indicated that BCLAF1 promoted tumorigenicity of HCC cells in vivo. More importantly, high expression of BCLAF1 might contribute to sorafenib resistance in HCC patients.

CONCLUSIONS

BCLAF1 is a potential oncogene in HCC by inducing autophagy to maintain tumor cell growth in response to stress conditions, and it could serve as a potential biomarker for predicting the prognosis of HCC patients and screening patients who are suitable for sorafenib therapy.

Chicoric acid (CA) induces autophagy in gastric cancer through promoting endoplasmic reticulum (ER) stress regulated by AMPK

Gastric cancer is one of the most common cancers leading to tumor-related deaths worldwide. Chicoric acid (CA) exhibits a variety of protective effects in different diseases. However, its role in regulating tumor progression has not been reported. Autophagy, as a conserved catabolic process, sustains cellular homoeostasis responding to stress to modulate cell fate. In the study, the effects of CA on gastric cancer were investigated. The results indicated that CA treatment markedly reduced the cell viability and induced apoptosis in gastric cancer cells, and prevented tumor growth in an established xenograft gastric cancer model. Furthermore, CA exposure significantly induced autophagy both in gastric cancer cells and tumor samples, as evidenced by the up-regulated expression of LC3II. Moreover, phosphorylated AMP-activated protein kinase (AMPK) and p70S6 kinase (p70s6k) expression were obviously promoted by CA in vitro and in vivo. Importantly, blocking AMPK activation abrogated CA-induced expression of LC3II in gastric cancer cells. In addition, endoplasmic reticulum (ER) stress in tumor samples or cells was markedly induced by CA treatment through promoting the expression of associated signals such as Parkin, protein kinase RNA-like ER kinase (PERK), activating transcription factors 4 (ATF4) and ATF6. Importantly, these effects were abolished by the inhibition of AMPK signaling. Collectively, our findings indicated that CA prevents human gastric cancer progression by inducing autophagy partly through the activation of AMPK, and represents an effective therapeutic strategy against gastric cancer development.

The PARK10 gene USP24 is a negative regulator of autophagy and ULK1 protein stability

Recent studies indicate a causative relationship between defects in autophagy and dopaminergic neuron degeneration in Parkinson disease (PD). However, it is not fully understood how autophagy is regulated in the context of PD. Here we identify USP24 (ubiquitin specific peptidase 24), a gene located in the PARK10 (Parkinson disease 10 [susceptibility]) locus associated with late onset PD, as a novel negative regulator of autophagy. Our data indicate that USP24 regulates autophagy by affecting ubiquitination and stability of the ULK1 protein. Knockdown of USP24 in cell lines and in human induced-pluripotent stem cells (iPSC) differentiated into dopaminergic neurons resulted in elevated ULK1 protein levels and increased autophagy flux in a manner independent of MTORC1 but dependent on the class III phosphatidylinositol 3-kinase (PtdIns3K) activity. Surprisingly, USP24 knockdown also improved neurite extension and/or maintenance in aged iPSC-derived dopaminergic neurons. Furthermore, we observed elevated levels of USP24 in the substantia nigra of a subpopulation of idiopathic PD patients, suggesting that USP24 may negatively regulate autophagy in PD.

Abbreviations: Bafilomycin/BafA: bafilomycin A₁; DUB: deubiquitinating enzyme; iPSC: induced pluripotent stem cells; MTOR: mechanistic target of rapamycin kinase; MTORC1: MTOR complex 1; nt: non-targeting; PD: Parkinson disease; p-ATG13: phospho-ATG13; PtdIns3P: phosphatidylinositol 3-phosphate; RPS6: ribosomal protein S6; SNPs: single nucleotide polymorphisms; TH: tyrosine hydroxylase; USP24: ubiquitin specific peptidase 24