Autophagy-Dependent Secretion: Crosstalk between Autophagy and Exosome Biogenesis

The cellular secretome is pivotal in mediating intercellular communication and coordinating responses to stressors. Exosomes, initially recognized for their role in waste disposal, have now emerged as key intercellular messengers with significant therapeutic and diagnostic potential. Similarly, autophagy has transcended its traditional role as a waste removal mechanism, emerging as a regulator of intracellular communication pathways and a contributor to a unique autophagy-dependent secretome. Secretory authophagy, initiated by various stress stimuli, prompts the selective release of proteins implicated in inflammation, including leaderless proteins that bypass the conventional endoplasmic reticulum-Golgi secretory pathway. This reflects the significant impact of stress-induced autophagy on cellular secretion profiles, including the modulation of exosome release. The convergence of exosome biogenesis and autophagy is exemplified by the formation of amphisomes, vesicles that integrate autophagic and endosomal pathways, indicating their synergistic interplay. Regulatory proteins common to both pathways, particularly mTORC1, emerge as potential therapeutic targets to alter cellular secretion profiles involved in various diseases. This review explores the dynamic interplay between autophagy and exosome formation, highlighting the potential to influence the secretome composition. While the modulation of exosome secretion and cytokine preconditioning is well-established in regenerative medicine, the strategic manipulation of autophagy is still underexplored, presenting a promising but uncharted therapeutic landscape.

KCNQ1OT1 polymorphism rs35622507 and methylation status of KCNQ1OT1 promoter influence the drug resistance to L-OHP

Background: LncRNA potassium voltage-gated channel subfamily Q member 1 opposite strand/antisense transcript 1 (KCNQ1OT1) has been reported to promote resistance to chemotherapy in colon cancer by inhibiting the expression of miR-34a. And the methylation of KCNQ1OT1 was also reported in the pathogenesis of various diseases. In this study, we aimed to study the combined effect of allele variation of KCNQ1OT1 polymorphism rs35622507 and methylation status of KCNQ1OT1 promoter in the treatment of colon cancer.

Methods: The expression levels of KCNQ1OT1, miR-34a, and ATG4B mRNA were assessed by qRT-PCR. ATG4B protein expression was analyzed by Western blot analysis. TUNEL and MTT assay were performed to examine the cell apoptosis and viability. Luciferase assays revealed the relationship between KCNQ1OT1, miR-34a and ATG4B.

Results: Carrier of allele 10 and methylated promoter in KCNQ1OT1 was associated with decreased KCNQ1OT1/ATG4B expression, increased miR-34a expression and enhanced apoptosis in colon cancer tissue samples. And subsequent luciferase assay showed that miR-34a could bind to KCNQ1OT1 and ATG4B at specific binding sites. The knockdown of KCNQ1OT1 significantly suppressed the KCNQ1OT1/ATG4B expression, improved the miR-34a expression and reduced the viability of HCT116 and SW480 cells. The over-expression of ATG4B notably restored the cell viability loss and apoptosis increase induced by the knockdown of KCNQ1OT1. Moreover, oxaliplatin (L-OHP) treatment elevated the apoptosis of HCT116 and SW480 cells.

Conclusions: The drug resistance in the treatment of colon cancer is most reduced in patients carrying allele 10 and methylated in KCNQ1OT1 promoter. This function is accomplished by the signaling pathway of KCNQ1OT1/miR-34a/ATG4B.

Tumor treating fields: a comprehensive overview of the underlying molecular mechanism

INTRODUCTION

As a novel treatment modality, tumor treating fields (TTFields) exert low-intensity, medium-frequency electric fields on tumor cells. TTFields' effectiveness and safety have been demonstrated clinically and in the real world for treating glioblastoma, the most common and aggressive primary central nervous system tumor. TTFields therapy has also been approved for the management of malignant mesothelioma, and clinical trials are ongoing for NSCLC, gastric cancer, pancreatic cancer, and other solid tumors.

AREAS COVERED

This article comprehensively reviews the currently described evidence of TTFields' mechanism of action. TTFields' most evident therapeutic effect is to induce cell death by disrupting mitosis. Moreover, evidence suggests at additional mechanistic complexity, such as delayed DNA repair and heightened DNA replication stress, reversible increase in cell membrane and blood-brain barrier permeability, induction of immune response, and so on.

EXPERT OPINION

TTFields therapy has been arising as the fourth anti-tumor treatment besides surgery, radiotherapy, and antineoplastic agents in recent years. However, the precise molecular mechanisms underlying the effects of TTFields are not fully understood and some concepts remain controversial. An in-depth understanding of TTFields' effects on tumor cell and tumor microenvironment would be crucial for informing research aimed at further optimizing TTFields' efficacy and developing new combination therapies for clinical applications.

Autophagy Process in Trophoblast Cells Invasion and Differentiation: Similitude and Differences With Cancer Cells

Early human placental development begins with blastocyst implantation, then the trophoblast differentiates and originates the cells required for a proper fetal nutrition and placental implantation. Among them, extravillous trophoblast corresponds to a non-proliferating trophoblast highly invasive that allows the vascular remodeling which is essential for appropriate placental perfusion and to maintain the adequate fetal growth. This process involves different placental cell types as well as molecules that allow cell growth, cellular adhesion, tissular remodeling, and immune tolerance. Remarkably, some of the cellular processes required for proper placentation are common between placental and cancer cells to finally support tumor growth. Indeed, as in placentation trophoblasts invade and migrate, cancer cells invade and migrate to promote tumor metastasis. However, while these processes respond to a controlled program in trophoblasts, in cancer cells this regulation is lost. Interestingly, it has been shown that autophagy, a process responsible for the degradation of damaged proteins and organelles to maintain cellular homeostasis, is required for invasion of trophoblast cells and for vascular remodeling during placentation. In cancer cells, autophagy has a dual role, as it has been shown both as tumor promoter and inhibitor, depending on the stage and tumor considered. In this review, we summarized the similarities and differences between trophoblast cell invasion and cancer cell metastasis specifically evaluating the role of autophagy in both processes.

PKM2 promotes cell metastasis and inhibits autophagy via the JAK/STAT3 pathway in hepatocellular carcinoma

Pyruvate kinase M2 (PKM2) is a member of the pyruvate kinase family. It has been recently reported that PKM2 displays non-metabolic activities. Nevertheless, understanding of the role of PKM2 in hepatocellular carcinoma (HCC) is insufficient. Therefore, our study aimed at exploring the impact of PKM2 on malignant growth, autophagy as well as invasion in HCC. Expression of PKM2 in HCC specimens was examined by qRT-PCR and western blot. PKM2 knock down was generated in vitro by shRNA. Activities of malignant cells as well as downstream pathways were assessed. The MTT assay was carried out to evaluate HCC proliferation, and the FACS assay was conducted to study cell death. Elevated PKM2 levels were observed in HCC samples. Knockdown (KD) of PKM2 triggered apoptosis as well as autophagy and inhibited migration and proliferation of HCC cells. Furthermore, PKM2 KD reinforced JAK/STAT3 pathway stimulation. STAT3 inhibition counteracted the impact of PKM2 on proliferation, autophagy, migration as well as cell death in HCC. To conclude, the findings of our research suggest that PKM2 reinforced metastasis and inhibited autophagy in HCC through the JAK/STAT3 pathway, and that PKM2 could serve as a promising target for HCC treatment.

Crosstalk between exosomes and autophagy: A review of molecular mechanisms and therapies

Exosomes are extracellular vesicles that primarily exist in bodily fluids such as blood. Autophagy is an intracellular degradation process, which, along with exosomes, can significantly influence human health and has therefore attracted considerable attention in recent years. Exosomes have been shown to regulate the intracellular autophagic process, which, in turn, affects the circulating exosomes. However, crosstalk between exosomal and autophagic pathways is highly complex, depends primarily on the environment, and varies greatly in different diseases. In addition, studies have demonstrated that exosomes, from specific cell, can mitigate several diseases by regulating autophagy, which can also affect the excessive release of some harmful exosomes. This phenomenon lays a theoretical foundation for the improvement of many diseases. Herein, we review the mechanisms and clinical significance of the association and regulation of exosomes and autophagy, in order to provide a new perspective for the prevention and treatment of associated diseases.

Resveratrol suppresses melanoma growth by promoting autophagy through inhibiting the PI3K/AKT/mTOR signaling pathway

Resveratrol (RV) is a natural polyphenolic phytoalexin derived from peanuts, red grape skins and red wine, and has been demonstrated to alleviate multiple types of malignancies. However, how RV achieves this in melanoma is unknown. The aim of present study was to investigate the role of RV in melanoma, using Cell Counting Kit-8, flow cytometry and western blot analysis. RV inhibited melanoma cell viability, migration and invasion counteracting melanoma progression. In addition, proteins associated with autophagy, including Beclin 1 and microtubule-associated protein 1A/1B-light chain 3 (LC3)-II/I, were upregulated, whereas p62 expression was downregulated in RV-treated cells. The number of LC3+ puncta, which can be applied to represent autophagosome formation, increased following RV treatment, suggesting that RV may trigger autophagy in melanoma cells. Treatment with the autophagy inhibitor, 3-methyladenine, reversed the RV-dependent inhibition of viability, migration and invasion of melanoma cells. RV treatment also reduced the ratios of phosphorylated (p)-AKT/AKT and p-mTOR/mTOR in melanoma cells. In conclusion, these findings suggested that RV may inhibit the viability and migration of melanoma cells through inhibiting the AKT/mTOR pathway, thus triggering autophagy. This indicated that RV may serve as an innovative therapeutic for melanoma treatment.

MTMR3 is upregulated in patients with breast cancer and regulates proliferation, cell cycle progression and autophagy in breast cancer cells

As a member of the myotubularin family, myotubularin related protein 3 (MTMR3) has been demonstrated to participate in tumor development, including oral and colon cancer. However, little is known about its functional roles in breast cancer. In the present study, the expression of MTMR3 in breast cancer was evaluated by immunohistochemical staining of tumor tissues from 172 patients. Online data was then used for survival analysis from the PROGgeneV2 database. In vitro, MTMR3 expression was silenced in MDA-MB-231 cells via lentiviral shRNA transduction. MTT, colony formation and flow cytometry assays were performed in the control and MTMR3-silenced cells to evaluate the cell growth, proliferation and cell cycle phase distribution, respectively. Western blotting was used to evaluate the protein expression levels of autophagy-related markers. The results demonstrated that the expression of MTMR3 in breast cancer tissues was significantly increased compared with adjacent normal tissues. MTMR3 was highly expressed in triple-negative breast cancer and was associated with disease recurrence. MTMR3 knockdown in MDA-MB-231 cells inhibited cell proliferation and induced cell cycle arrest and autophagy. The present results indicated that MTMR3 may have an important role in promoting the progression of breast cancer, and its inhibition may serve as a promising therapeutic target for breast cancer treatment.

WZY-321, a novel evodiamine analog, inhibits glioma cell growth in an autophagy-associated manner

Glioblastoma is one of the most aggressive types of brain tumor. The median survival rate of patients with glioblastoma (World Health Organization grade IV) is <15 months. Therefore, there is an urgent requirement for the development of novel and efficient therapeutic agents against glioma. In previous studies, WZY-321 (10-hydroxy-1-methyl-8,13b-dihydro-5H,7H-benzo[e]benzofuro[2',3':3,4]pyrido[2,1-b][1,3]oxazin-5-one), a novel evodiamine (Evo) analog, was reported to exhibit enhanced pharmacological properties and improved cytotoxicity against a number of human cancer cell lines compared with Evo. In the current study, the anti-proliferative effect of WZY-321 on SHG-44 and SWO-38 glioma cells was further studied, and its mechanism of action investigated. The results indicated that WZY-321 inhibited the proliferation of SHG-44 cells in a dose- and time-dependent manner by enhancing cellular apoptosis and inducing cell cycle arrest at the G2-M phase. Treatment of glioma cells with WZY-321 concomitantly increased the expression levels of microtubule associated protein 1 light chain 3α and Beclin1, indicating enhanced autophagy. Overall, the results of the present study revealed the anti-proliferative potential of WZY-321 in glioma cells, thus providing a possible autophagy-based therapeutic strategy for the treatment of glioblastoma.

AMPK-dependent autophagy upregulation serves as a survival mechanism in response to Tumor Treating Fields (TTFields)

Tumor Treating Fields (TTFields), an approved treatment modality for glioblastoma, are delivered via non-invasive application of low-intensity, intermediate-frequency, alternating electric fields. TTFields application leads to abnormal mitosis, aneuploidy, and increased cell granularity, which are often associated with enhancement of autophagy. In this work, we evaluated whether TTFields effected the regulation of autophagy in glioma cells. We found that autophagy is upregulated in glioma cells treated with TTFields as demonstrated by immunoblot analysis of the lipidated microtubule-associated protein light chain 3 (LC3-II). Fluorescence and transmission electron microscopy demonstrated the presence of LC3 puncta and typical autophagosome-like structures in TTFields-treated cells. Utilizing time-lapse microscopy, we found that the significant increase in the formation of LC3 puncta was specific to cells that divided during TTFields application. Evaluation of selected cell stress parameters revealed an increase in the expression of the endoplasmic reticulum (ER) stress marker GRP78 and decreased intracellular ATP levels, both of which are indicative of increased proteotoxic stress. Pathway analysis demonstrated that TTFields-induced upregulation of autophagy is dependent on AMP-activated protein kinase (AMPK) activation. Depletion of AMPK or autophagy-related protein 7 (ATG7) inhibited the upregulation of autophagy in response to TTFields, as well as sensitized cells to the treatment, suggesting that cancer cells utilize autophagy as a resistance mechanism to TTFields. Combining TTFields with the autophagy inhibitor chloroquine (CQ) resulted in a significant dose-dependent reduction in cell growth compared with either TTFields or CQ alone. These results suggest that dividing cells upregulate autophagy in response to aneuploidy and ER stress induced by TTFields, and that AMPK serves as a key regulator of this process.

Microgravity induces autophagy via mitochondrial dysfunction in human Hodgkin's lymphoma cells

Gravitational forces can impose physical stresses on the human body as it functions to maintain homeostasis. It has been reported that astronauts exposed to microgravity experience altered biological functions and many subsequent studies on the effects of microgravity have therefore been conducted. However, the anticancer mechanisms of simulated microgravity remain unclear. We previously showed that the proliferation of human Hodgkin's lymphoma (HL) cells was inhibited when these cells were cultured in time-averaged simulated microgravity (taSMG). In the present study, we investigated whether taSMG produced an anticancer effect. Exposure of human HL cells to taSMG for 2 days increased their reactive oxygen species (ROS) production and NADPH oxidase family gene expression, while mitochondrial mass, ATPase, ATP synthase, and intracellular ATP levels were decreased. Furthermore, human HL cells exposed to taSMG underwent autophagy via AMPK/Akt/mTOR and MAPK pathway modulation; such autophagy was inhibited by the ROS scavenger N-acetylcysteine (NAC). These results suggest an innovative therapeutic approach to HL that is markedly different from conventional chemotherapy and radiotherapy.

Autophagy inhibition enhances radiosensitivity of Eca‑109 cells via the mitochondrial apoptosis pathway

Autophagy inhibition is crucial for the improvement of the efficacy of radiotherapy in cancer. The aim of the present study was to determine the potential therapeutic value of autophagy and its correlation with mitochondria in human esophageal carcinoma cells following treatment with ionizing radiation (IR). Autophagy in Eca-109 cells was induced under poor nutrient conditions. The formation of autophagic vacuoles was monitored using electron microscopy. In addition, cell apoptosis after IR and mitochondrial membrane potential (MMP) were analyzed by flow cytometry. LC3, beclin-1, cytochrome c and apoptosis-related proteins were assayed by western blotting. A nude mouse xenograft model was also employed to verify the biological effects and mechanisms underlying autophagy in vivo. The formed autophagic vesicles and increased LC3 II/LC3 I ratio indicated marked induction of autophagy by Earle's balanced salt solution (EBSS) in Eca-109 cells. 3-Methyladenine or LY294002 significantly antagonized EBSS-induced autophagy and increased apoptosis of irradiated cells, suggesting that autophagy inhibition conferred radiosensitivity in vitro. Notably, IR induced prominent release of cytochrome c and Bax activation, and decreased Bcl-2 and MMP expression in Eca-109 cells under poor nutrient conditions. Of note, these changes were more prominent following pretreatment with autophagy inhibitors. In vivo, IR treatment mildly delayed tumor growth, but the radiotherapeutic effect was improved significantly by abolishing autophagy. Furthermore, mitochondrial signaling was investigated in the Eca-109 xenograft nude mice model, and the results were consistent with the in vitro study. Therefore, the mitochondrial pathway may be associated with improvement of radiosensitivity in Eca-109 cells.

Selective anticancer activity of the novel thiobenzanilide 63T against human lung adenocarcinoma cells

Previously, it has been reported that molecules built on the benzanilide and thiobenzanilide scaffold are the promising groups of compounds with several biological activities including antifungal, antimycotic, antibacterial, spasmolytic, and anticancer ones. In this study the mechanism of action of one selected thiobenzanilide derivative N,N'-(1,2-phenylene)bis3,4,5-trifluorobenzothioamide (63T) with strongest cytotoxic activity has been investigated for the first time in human lung adenocarcinoma (A549) and normal lung derived fibroblast (CCD39Lu) in a cell culture model. The results demonstrated, that 63T can be considered a selective anticancer compound. Based on these results, several experiments including the analysis of cellular morphology, cell phase distribution, cytoplasmic histone-associated DNA fragmentation, apoptosis, necrosis, and autophagy detection were performed to understand better the mechanism underlying the anticancer activity. The data showed that 63T is a small molecule compound, which selectively induces cancer cell death in a caspase independent pathway; moreover, the autophagic dose-dependent processes may be involved in the mechanism of cell death.

Sorafenib-induced defective autophagy promotes cell death by necroptosis

Autophagy is one of the main cytoprotective mechanisms that cancer cells deploy to withstand the cytotoxic stress and survive the lethal damage induced by anti-cancer drugs. However, under specific conditions, autophagy may, directly or indirectly, induce cell death. In our study, treatment of the Atg5-deficient DU145 prostate cancer cells, with the multi-tyrosine kinase inhibitor, sorafenib, induces mitochondrial damage, autophagy and cell death. Molecular inhibition of autophagy by silencing ULK1 and Beclin1 rescues DU145 cells from cell death indicating that, in this setting, autophagy promotes cell death. Re-expression of Atg5 restores the lipidation of LC3 and rescues DU145 and MEF atg5−/− cells from sorafenib-induced cell death. Despite the lack of Atg5 expression and LC3 lipidation, DU145 cells form autophagosomes as demonstrated by transmission and immuno-electron microscopy, and the formation of LC3 positive foci. However, the lack of cellular content in the autophagosomes, the accumulation of long-lived proteins, the presence of GFP-RFP-LC3 positive foci and the accumulated p62 protein levels indicate that these autophagosomes may not be fully functional. DU145 cells treated with sorafenib undergo a caspase-independent cell death that is inhibited by the RIPK1 inhibitor, necrostatin-1. Furthermore, treatment with sorafenib induces the interaction of RIPK1 with p62, as demonstrated by immunoprecipitation and a proximity ligation assay. Silencing of p62 decreases the RIPK1 protein levels and renders necrostatin-1 ineffective in blocking sorafenib-induced cell death. In summary, the formation of Atg5-deficient autophagosomes in response to sorafenib promotes the interaction of p62 with RIPK leading to cell death by necroptosis.

The pancreatitis-associated protein VMP1, a key regulator of inducible autophagy, promotes Kras(G12D)-mediated pancreatic cancer initiation

Both clinical and experimental evidence have firmly established that chronic pancreatitis, in particular in the context of Kras oncogenic mutations, predisposes to pancreatic ductal adenocarcinoma (PDAC). However, the repertoire of molecular mediators of pancreatitis involved in Kras-mediated initiation of pancreatic carcinogenesis remains to be fully defined. In this study we demonstrate a novel role for vacuole membrane protein 1 (VMP1), a pancreatitis-associated protein critical for inducible autophagy, in the regulation of Kras-induced PDAC initiation. Using a newly developed genetically engineered model, we demonstrate that VMP1 increases the ability of Kras to give rise to preneoplastic lesions, pancreatic intraepithelial neoplasias (PanINs). This promoting effect of VMP1 on PanIN formation is due, at least in part, by an increase in cell proliferation combined with a decrease in apoptosis. Using chloroquine, an inhibitor of autophagy, we show that this drug antagonizes the effect of VMP1 on PanIN formation. Thus, we conclude that VMP1-mediated autophagy cooperate with Kras to promote PDAC initiation. These findings are of significant medical relevance, molecules targeting autophagy are currently being tested along chemotherapeutic agents to treat PDAC and other tumors in human trials.

Targeting autophagy to overcome drug resistance in cancer therapy

Autophagy, a catabolic process, is activated by conditions of stress and nutrient deprivation, which occurs to maintain metabolic homeostasis by performing catabolic lysis of excessive or unnecessary proteins, and injured or aged organelles. Autophagy is regulated by various signaling pathways. Main regulators of autophagy are the PI3K-Akt-mTOR pathway, Beclin1, Bcl-2, Ras and p53. Autophagy plays dual role in cancer, shows both tumor suppressive and oncogenic activity. It is accepted that drug resistance in cancer cells can be overcome by inhibition of autophagy. Herein, we summarize autophagy as a potential target of anticancer drugs and targeting autophagy provides a promising therapeutic strategy to circumvent resistance and enhance the effect of anticancer therapies for cancer patients.

Novel and emerging targeted-based cancer therapy agents and methods

After several decades of uncovering the cancer features and following the improvement of therapeutic agents, however cancer remains as one of the major reasons of mortality. Chemotherapy is one of the main treatment options and has significantly improved the overall survival of cancer patients, but chemotherapeutic agents are highly toxic for normal cells. Therefore, there is a great unmet medical need to develop new therapeutic principles and agents. Targeted-based cancer therapy (TBCT) agents and methods have revolutionized the cancer treatment efficacy. Monoclonal antibodies (mAbs) and small molecule inhibitors (SMIs) are among the most effective agents of TBCT. These drugs have improved the prognosis and survival of cancer patients; however, the therapeutic resistance has subdued the effects. Several mechanisms lead to drug resistance such as mutations in the drug targets, activation of compensatory pathways, and intrinsic or acquired resistance of cancer stem cells. Therefore, new modalities, improving current generation of inhibitors and mAbs, and optimizing the combinational therapy regimens are necessary to decrease the current obstacles in front of TBCT. Moreover, the success of new TBCT agents such as mAbs, SMIs, and immunomodulatory agents has sparked further therapeutic modalities with novel targets to inhibit. Due to the lack of cumulative information describing different agents and methods of TBCT, this review focuses on the most important agents and methods of TBCT that are currently under investigation.

The prosurvival role of autophagy in resveratrol-induced cytotoxicity in GH3 cells

In a previous study, we reported that resveratrol exerts antitumor effects through the estrogen receptor in prolactinoma. The autophagy/lysosomal degradation pathway plays an important role in damage control and energy efficiency. In this study, we investigated the involvement of autophagy and the related signaling pathways in resveratrol-induced apoptosis of GH3 cells. We demonstrate that resveratrol inhibits cell proliferation and induces apoptosis in a dose-dependent manner in GH3 cells. The cleavage of PARP was also observed, and the activation of caspase-3 and caspase-8 was detected. Consistent with this finding, the inhibition of caspase activation effectively attenuated resveratrol-induced cell apoptosis. In addition, the decreased level of Bcl-2 was also observed. The induction of autophagy was confirmed by the detection of the formation of autophagic vacuoles, and the increase in microtubule-associated protein 1 light chain 3 (LC3)-II and beclin-1 levels, two hallmarks of autophagy. Pre-treatment with bafilomycin A1 or 3-methyladenine, inhibitors of autophagy, enhanced the resveratrol-mediated caspase activation and cell death. Moreover, resveratrol induced the activation of ERK1/2, as well as the downregulation of Akt and mTOR phosphorylation. Taken together, these findings indicate that resveratrol induces caspase-dependent apoptosis and decreases Bcl-2 levels. In addition, resveratrol-induced autophagy is regulated by the PI3K/Akt/mTOR and ERK1/2 pathways. Furthermore, the inhibition of autophagy increases the cytotoxicity of resveratrol to GH3 cells.

Neuroprotective effects of autophagy induced by rapamycin in rat acute spinal cord injury model

BACKGROUND/AIMS

To explore the effects of rapamycin-induced autophagy on apoptosis in a rat model of acute spinal cord injury (SCI), and to explore the effect of rapamycin on apoptosis in primary spinal cord cell culture.

METHODS

SCI was induced at T10 in female adult Sprague-Dawley rats. After injury was induced, the rats were injected with rapamycin and/or methylprednisolone and were sacrificed at various days after injury. Apoptosis and autophagy were examined with TUNEL staining and electron microscopy. Hind limb function was assessed by the Gale scale.

RESULTS

The expression of the apoptosis-related protein caspase-3 did not significantly increase until 21 days following injury, while increases in LC3II and LC3I began 10 days after injury, but then declined. TUNEL staining and electron microscopy confirmed that following injury autophagy occurred before apoptosis, but by 14 days after the injury, the level of autophagy had decreased significantly while the level of apoptosis showed a continued increase. Following treatment with rapamycin, apoptosis was significantly higher than in the vehicle control group, but significantly lower than in the sham-operated group, showing a protective effect of rapamycin. Gale scale grades in rats treated with rapamycin were significantly higher compared with the vehicle control group, suggesting a functional effect of rapamycin-induced inhibition of apoptosis.

CONCLUSIONS

The results indicate that rapamycin significantly improved the prognosis of acute SCI in rats by inhibiting cell apoptosis. Rapamycin might be useful as a therapeutic agent for acute SCI.

Grape seed extract and resveratrol prevent 4-nitroquinoline 1-oxide induced oral tumorigenesis in mice by modulating AMPK activation and associated biological responses

Preventive measures against oral carcinogenesis are urgently warranted to lower the high morbidity and mortality associated with this malignancy worldwide. Here, we investigated the chemopreventive efficacy of grape seed extract (GSE) and resveratrol (Res) in 4-nitroquinoline-1-oxide (4NQO)-induced tongue tumorigenesis in C57BL/6 mice. Following 8 weeks of 4NQO exposure (100 µg/ml in drinking water), mice were fed with either control AIN-76A diet or diet containing 0.2% GSE (w/w) or 0.25% Res (w/w) for 8 subsequent weeks, while continued on 4NQO. Upon termination of the study at 16 weeks, tongue tissues were histologically evaluated for hyperplasia, dysplasia, and papillary lesions, and then analyzed for molecular targets by immunohistochemistry. GSE and Res feeding for 8 weeks, moderately decreased the incidence, but significantly prevented the multiplicity and severity of 4NQO-induced preneoplastic and neoplastic lesions, without any apparent toxicity. In tongue tissues, both 4NQO + GSE and 4NQO + Res treatment correlated with a decreased proliferation (BrdU labeling index) but increased apoptotic death (TUNEL-positive cells) as compared to the 4NQO group. Furthermore, tongue tissues from both the 4NQO + GSE and 4NQO + Res groups showed an increase in activated metabolic regulator phospho-AMPK (Thr172) and decreased autophagy flux marker p62. Together, these findings suggest that GSE and Res could effectively prevent 4NQO-induced oral tumorigenesis through modulating AMPK activation, and thereby, inhibiting proliferation and inducing apoptosis and autophagy, as mechanisms of their efficacy.

Autophagy during beef aging

The conversion of muscle into meat is a complex process of major concern for meat scientists due to its influence on the final meat quality. The aim of this study was to investigate the occurrence of autophagic processes in the conversion of muscle into meat. Our findings demonstrated, for the first time, the occurrence of autophagic processes in the muscle tissue at early postmortem period (2 h to 24 h) in both beef breeds studied (Asturiana de los Valles and Asturiana de la Montaña) showing significant time-scale differences between breeds, which could indicate a role of this process in meat maturation. These breeds have different physiological features: while Asturiana de los Valles is a meat-specialized breed showing high growth rate, an elevated proportion of white fibers in the muscle and low intramuscular fat level, Asturiana de la Montaña is a small- to medium-sized rustic breed adapted to less-favored areas, showing more red fibers in the muscle and a high intramuscular fat content.

High dose of extracellular ATP switched autophagy to apoptosis in anchorage-dependent and anchorage-independent hepatoma cells

Extracellular adenosine triphosphate (eATP) transduces purinergic signal and plays an important regulatory role in many biological processes, including tumor cell growth and cell death. A large amount of eATP exists in the fast-growing tumor center and inflammatory tumor microenvironment. Tumor cells could acquire anoikis resistance and anchorage independence in tumor microenvironment and further cause metastatic lesion. Whether such a high amount of eATP has any effect on the anchored and non-anchored tumor cells in tumor microenvironment has not been elucidated and is investigated in this study. Our data showed that autophagy helped hepatoma cells to maintain survival under the treatment of no more than 1 mM of eATP. Only when eATP concentration reached a relatively high level (2.5 mM), cell organelle could not be further maintained by autophagy, and apoptosis and cell death occurred. In hepatoma cells under treatment of 2.5 mM of eATP, an AMP-activated protein kinase (AMPK) pathway was dramatically activated while mTOR signaling pathway was suppressed in coordination with apoptosis. Further investigation showed that the AMPK/mTOR axis played a key role in tipping the balance between autophagy-mediated cell survival and apoptosis-induced cell death under the treatment of eATP. This work provides evidence to explain how hepatoma cells escape from eATP-induced cytotoxicity as well as offers an important clue to consider effective manipulation of cancer.

The inhibition of autophagy sensitises colon cancer cells with wild-type p53 but not mutant p53 to topotecan treatment

Background

Topotecan produces DNA damage that induces autophagy in cancer cells. In this study, sensitising topotecan to colon cancer cells with different P53 status via modulation of autophagy was examined.

Methodology/Principal Findings

The DNA damage induced by topotecan treatment resulted in cytoprotective autophagy in colon cancer cells with wild-type p53. However, in cells with mutant p53 or p53 knockout, treatment with topotecan induced autophagy-associated cell death. In wild-type p53 colon cancer cells, topotecan treatment activated p53, upregulated the expression of sestrin 2, induced the phosphorylation of the AMPKα subunit at Thr172, and inhibited the mTORC1 pathway. Furthermore, the inhibition of autophagy enhanced the anti-tumour effect of topotecan treatment in wild-type p53 colon cancer cells but alleviated the anti-tumour effect of topotecan treatment in p53 knockout cells in vivo.

Conclusions/Significance

These results imply that the wild-type p53-dependent induction of cytoprotective autophagy is one of the cellular responses that determines the cellular sensitivity to the DNA-damaging drug topotecan. Therefore, our study provides a potential therapeutic strategy that utilises a combination of DNA-damaging agents and autophagy inhibitors for the treatment of colon cancer with wild-type p53.

Targeting of distinct signaling cascades and cancer-associated fibroblasts define the efficacy of Sorafenib against prostate cancer cells

Sorafenib, a multi-tyrosine kinase inhibitor, kills more effectively the non-metastatic prostate cancer cell line 22Rv1 than the highly metastatic prostate cancer cell line PC3. In 22Rv1 cells, constitutively active STAT3 and ERK are targeted by sorafenib, contrasting with PC3 cells, in which these kinases are not active. Notably, overexpression of a constitutively active MEK construct in 22Rv1 cells stimulates the sustained phosphorylation of Bad and protects from sorafenib-induced cell death. In PC3 cells, Src and AKT are constitutively activated and targeted by sorafenib, leading to an increase in Bim protein levels. Overexpression of constitutively active AKT or knockdown of Bim protects PC3 cells from sorafenib-induced killing. In both PC3 and 22Rv1 cells, Mcl-1 depletion is required for the induction of cell death by sorafenib as transient overexpression of Mcl-1 is protective. Interestingly, co-culturing of primary cancer-associated fibroblasts (CAFs) with 22Rv1 or PC3 cells protected the cancer cells from sorafenib-induced cell death, and this protection was largely overcome by co-administration of the Bcl-2 antagonist, ABT737. In summary, the differential tyrosine kinase profile of prostate cancer cells defines the cytotoxic efficacy of sorafenib and this profile is modulated by CAFs to promote resistance. The combination of sorafenib with Bcl-2 antagonists, such as ABT737, may constitute a promising therapeutic strategy against prostate cancer.

The expression of p33(ING1), p53, and autophagy-related gene Beclin1 in patients with non-small cell lung cancer

The purpose of this study was to investigate the expressions of tumor inhibitor of growth (ING1) gene p33ING1, p53, and autophagy-related gene Beclin1 in human non-small cell lung cancer (NSCLC), and the correlation between their expressions with clinical pathological features and clinical significance. The research can provide new ideas and experimental evidence for early diagnosis and biotherapy for NSCLC in the future. The human NSCLC tissues and surrounding non-cancerous tissues were collected from surgical operation. The expressions of mRNA or protein of p33ING1, p53, and Beclin1 were detected by using of reverse transcription polymerase chain reaction or Western blot in these tissues. The results were used to analyze the relationships between these gene expressions with the developing of NSCLC and clinical pathological features. The expressions of mRNA or protein of p33ING1 and Beclin1 in NSCLC tissues were significantly lower than that in surrounding noncancerous tissues (p < 0.05). The expressions of mRNA or protein of p33ING1 and Beclin1 in well- and middle-differentiated NSCLC tissues were lower than those in poor-differentiated NSCLC tissues (p < 0.05). The expressions of mRNA or protein of p33ING1 and Beclin1 in presence of lymph nodes metastasis were lower than those in absence of lymph nodes metastasis (p < 0.05). The expressions of mRNA or protein of p33ING1 and Beclin1 in patients of pathological stage (stages I-II) were higher than those in pathological stage (stages III-IV) (p < 0.05). But the expression of protein of mutant-type p53 in NSCLC tissues was significantly higher than that in surrounding non-cancerous tissues (p < 0.05). The expressions of protein of mutant-type p53 in well- and middle-differentiated NSCLC tissues were higher than those in poor-differentiated NSCLC tissues (p < 0.05). The expressions of protein of mutant-type p53 in presence of lymph nodes metastasis were higher than those in absence of lymph nodes metastasis (p < 0.05). The expressions of protein of mutant-type p53 in patients of pathological stage (stages I-II) were lower than those in pathological stage (stages III-IV) (p < 0.05). These expression changes of p33ING1, p53, and autophagy-related Beclin1 genes were associated with tumor cell differentiation, lymph nodes metastasis, and pathological stage of NSCLC. But these expression changes of these three genes were not associated with gender, age, size of primary carcinoma, histological type of NSCLC (p > 0.05). The expression of mRNA of p53 and Beclin1 were correlated with p33ING1 mRNA expression in NSCLC tissues (p < 0.05). The activity changes of tumor inhibitor of growth, autophagy, and apoptosis may be related to the emergence and the development of NSCLC. The combined detection of p33ING1, p53, and Beclin1 genes and proteins will be helpful for early diagnosis and prognosis judgment for NSCLC, and can provide experimental evidence for biotherapy of NSCLC.

Glyoxalase in tumourigenesis and multidrug resistance

Since the discovery by Warburg of high aerobic glycolysis in most tumours in the 1920s, it has remained unclear how to exploit this in chemotherapy. The aim of this review is to assess the evidence for the involvement of the glyoxalase system in tumour growth and multidrug resistance and the importance of the glyoxalase system as a target for anticancer drug development and a source of biomarkers for tumour diagnosis. Increased expression of glyoxalase 1 appears to support the viability of tumour cells with high glycolytic rates. Multidrug resistance conferred by overexpression of glyoxalase 1 suggests mechanisms of toxicity of most current antitumour agents involve, in some part, accumulation of methylglyoxal to cytotoxic levels. The recent finding of glyoxalase 1 gene amplification in tumours and induction of increased glyoxalase 1 expression by malignant transformation and conventional antitumour drug treatment implies a critical role of glyoxalase 1 in innate and acquired multidrug resistance in cancer treatment. Improved understanding of glyoxalase 1 in cancer chemotherapy multidrug resistance is likely vital to achieve improvement of cancer patient survival rates. Advances made to counter glyoxalase 1-linked multidrug resistance with glyoxalase 1 inhibitors and related prodrugs has been translated from in vitro to pre-clinical in vivo studies. Further research is required urgently for next stage clinical translation. Finally, overexpression of glyoxalase 1 may be linked to multidrug resistance in chemotherapy of other disease - such as microbial infections.