Targeting autophagy to modulate cell survival: a comparative analysis in cancer, normal and embryonic cells

Zebrafish live imaging: a strong weapon in anticancer drug discovery and development

Developing anticancer drugs is a complex and time-consuming process. The inability of current laboratory models to reflect important aspects of the tumor in vivo limits anticancer medication research. Zebrafish is a rapid, semi-automated in vivo screening platform that enables the use of non-invasive imaging methods to monitor morphology, survival, developmental status, response to drugs, locomotion, or other behaviors. Zebrafish models are widely used in drug discovery and development for anticancer drugs, especially in conjunction with live imaging techniques. Herein, we concentrated on the use of zebrafish live imaging in anticancer therapeutic research, including drug screening, efficacy assessment, toxicity assessment, and mechanism studies. Zebrafish live imaging techniques have been used in numerous studies, but this is the first time that these techniques have been comprehensively summarized and compared side by side. Finally, we discuss the hypothesis of Zebrafish Composite Model, which may provide future directions for zebrafish imaging in the field of cancer research.

Future prospects of bacteria-mediated cancer therapies: Affliction or opportunity?

Cancer, as a disease characterized by uncontrolled growth of cells, is recognized as one of the significant challenges in the field of health and medicine. There are various treatments for cancer like surgery, hormone therapy, chemotherapy, etc., but they have negative effects on the patient's lifestyle. Numerous side effects, and recently the emergence of drug resistance to these methods are weaknesses of these treatments. The utilization of bacteria as a treatment for cancer has attracted scientists' attention in the last decade. There are various methods of using bacteria to treat cancer, including the use of live, attenuated, or genetically engineered microbes, the use of bacterial toxins as an immunotoxin or conjugated to tumor antigens, bacteria-based cancer immunotherapy, bacterial vectors for gene-directed enzyme prodrug, and also the undeniable role of probiotics in treatment, are the cases that today are used for treatment. Bacterial therapy has shown a greater promise in cancer treatment due to its ability to lyse the tumor cells and deliver therapeutic products. However, the potential cytotoxicity of bacteria for healthy tissues, their inability to entirely lyse cancerous cells, and the possibility of mutations in their genomes are among the challenges of bacteriotherapy for cancer. Herein, we summarize the mechanism of bacteria, their potential benefits and harms, and the future of research in this field.

Albendazole-induced autophagy blockade contributes to elevated apoptosis in cholangiocarcinoma cells through AMPK/mTOR activation

Albendazole (ABZ) is a broad-spectrum anti-parasitic drug that exhibits antitumor effects against several carcinomas. The effects of ABZ on cholangiocarcinoma (CCA) and its underlying mechanisms are still unclear. Our study aims to investigate the role of ABZ in inducing autophagy-mediated apoptosis of cholangiocarcinoma cells. The antitumor effects of ABZ were evaluated against CCA cells and HIBEC intrahepatic biliary epithelial cells. Furthermore, the apoptosis rates, and autophagy flux in RBE and FRH-0201 cells treated with ABZ were investigated. ABZ inhibited proliferation, induced cell death and apoptosis in CCA cells in vitro. In vivo, tumors from ABZ- treated BALB/c nude mice were significantly smaller than untreated mice. ABZ also induced the initiation of autophagy via AMPK/mTOR pathways, resulting in the formation of autophagosome. In addition, ABZ blocked autophagic flux by inhibiting the fusion of autophagosome-lysosome, which increased the apoptotic death of CCA cells. However, the apoptotic death of CCA cells induced by ABZ was reversed by 3-methyladenine (3-MA), an autophagosome formation inhibitor, but increased by chloroquine (CQ), an autophagosome-lysosome fusion inhibitor.Our work provides novel mechanisms for anti-tumor effects of ABZ on CCA, suggesting that ABZ may be used as a potent autophagy inhibitor in the treatment of CCA.

Autophagy modulating agents as chemosensitizers for cisplatin therapy in cancer

Although cisplatin is one of the most common antineoplastic drug, its successful utilisation in cancer treatment is limited by the drug resistance. Multiple attempts have been made to find potential cisplatin chemosensitisers which would overcome cancer cells resistance thus improving antineoplastic efficacy. Autophagy modulation has become an important area of interest regarding the aforementioned topic. Autophagy is a highly conservative cellular self-digestive process implicated in response to multiple environmental stressors. The high basal level of autophagy is a common phenomenon in cisplatin-resistant cancer cells which is thought to grant survival benefit. However current evidence supports the role of autophagy in either promoting or limiting carcinogenesis depending on the context. This encourages the search of substances modulating the process to alleviate cisplatin resistance. Such a strategy encompasses not only simple autophagy inhibition but also harnessing the process to induce autophagy-dependent cell death. In this paper, we briefly describe the mechanism of cisplatin resistance with a special emphasis on autophagy and we give an extensive literature review of potential substances with cisplatin chemosensitising properties related to autophagy modulation.

Repurposing old drugs to fight multidrug resistant cancers

Overcoming multidrug resistance represents a major challenge for cancer treatment. In the search for new chemotherapeutics to treat malignant diseases, drug repurposing gained a tremendous interest during the past years. Repositioning candidates have often emerged through several stages of clinical drug development, and may even be marketed, thus attracting the attention and interest of pharmaceutical companies as well as regulatory agencies. Typically, drug repositioning has been serendipitous, using undesired side effects of small molecule drugs to exploit new disease indications. As bioinformatics gain increasing popularity as an integral component of drug discovery, more rational approaches are needed. Herein, we show some practical examples of in silico approaches such as pharmacophore modelling, as well as pharmacophore- and docking-based virtual screening for a fast and cost-effective repurposing of small molecule drugs against multidrug resistant cancers. We provide a timely and comprehensive overview of compounds with considerable potential to be repositioned for cancer therapeutics. These drugs are from diverse chemotherapeutic classes. We emphasize the scope and limitations of anthelmintics, antibiotics, antifungals, antivirals, antimalarials, antihypertensives, psychopharmaceuticals and antidiabetics that have shown extensive immunomodulatory, antiproliferative, pro-apoptotic, and antimetastatic potential. These drugs, either used alone or in combination with existing anticancer chemotherapeutics, represent strong candidates to prevent or overcome drug resistance. We particularly focus on outcomes and future perspectives of drug repositioning for the treatment of multidrug resistant tumors and discuss current possibilities and limitations of preclinical and clinical investigations.

Autophagy modulators for the treatment of oral and esophageal squamous cell carcinomas

Oral squamous cell carcinomas (OSCC) and esophageal squamous cell carcinomas (ESCC) exhibit a survival rate of less than 60% and 40%, respectively. Late-stage diagnosis and lack of effective treatment strategies make both OSCC and ESCC a significant health burden. Autophagy, a lysosome-dependent catabolic process, involves the degradation of intracellular components to maintain cell homeostasis. Targeting autophagy has been highlighted as a feasible therapeutic strategy with clinical utility in cancer treatment, although its associated regulatory mechanisms remain elusive. The detection of relevant biomarkers in biological fluids has been anticipated to facilitate early diagnosis and/or prognosis for these tumors. In this context, recent studies have indicated the presence of specific proteins and small RNAs, detectable in circulating plasma and serum, as biomarkers. Interestingly, the interplay between biomarkers (eg, exosomal microRNAs) and autophagic processes could be exploited in the quest for targeted and more effective therapies for OSCC and ESCC. In this review, we give an overview of the available biomarkers and innovative targeted therapeutic strategies, including the application of autophagy modulators in OSCC and ESCC. Additionally, we provide a viewpoint on the state of the art and on future therapeutic perspectives combining the early detection of relevant biomarkers with drug discovery for the treatment of OSCC and ESCC.

Morin Hydrate Reverses Cisplatin Resistance by Impairing PARP1/HMGB1-Dependent Autophagy in Hepatocellular Carcinoma

Chemoresistance is a major obstacle that limits the benefits of cisplatin-based chemotherapy in various cancers, including hepatocellular carcinoma. De-regulation of the poly(ADP-ribose) polymerase 1 (PARP1)/high-mobility group box 1 (HMGB1) signaling pathway has been proposed as an important mechanism involved in cisplatin-resistance. In this study, we investigated therapeutic potential of a natural flavonoid Morin hydrate against cisplatin-induced toxicity using the HepG2^DR multi-drug resistant cell line, which is derived from the HepG2 human hepatocellular carcinoma cell line. HepG2^DR cells were exposed to cisplatin and Morin hydrate alone or together after which autophagy and apoptotic signaling pathways were monitored by fluorometric assay and Western blot analysis. Xenograft mouse models were performed to confirm the in vitro effect of Morin hydrate. PARP1 was hyper activated in cisplatin-resistant HepG2^DR cells. Cisplatin-induced PARP1 activation resulted in chemoresistance via increased autophagy. The cisplatin/Morin hydrate combination was effective in the reversal of the HepG2^DR cell resistance via suppression of PARP1-mediated autophagy by regulating the HMGB1 and microtubule-associated protein 1A/1B light chain 3B (LC3) I/II. Moreover, PARP1 inhibition by 4-amino-1,8-naphthalimide or autophagy inhibition by a knockdown of the autophagy-related 5 (ATG5) gene resulted in sensitizing the HepG2^DR cells to cisplatin (CP) through activation of the c-Jun N-terminal kinase (JNK) pathway. In a mouse xenograft model, the treatment of cisplatin with Morin hydrate reversed the increased expression of PARP and HMGB1 and significantly suppressed tumor growth. These findings indicate dysregulated expression of PARP1 confers cisplatin-resistance via autophagy activation in HepG2^DR cells. Morin hydrate inhibits cisplatin-mediated autophagy induction, resulting in increased susceptibility of HepG2^DR cells to cisplatin cytotoxicity. The combination of Morin hydrate with cisplatin may be a promising therapeutic strategy to enhance the efficacy of conventional chemotherapeutic drugs.

Isatin inhibits the invasion of human neuroblastoma SH‑SY5Y cells, based on microarray analysis

Neuroblastoma is the fourth most common type of extracranial malignant solid tumor in children. Isatin had been demonstrated to have inhibitory effects on neuroblastoma tumors in vivo and in vitro. The aim of the present study was to investigate the molecular mechanism related to the anti-invasion effect of isatin on SH-SY5Y cells using microarray analysis. The microarray data identified a number of genes to be differentially upregulated or downregulated between isatin-treated cells and untreated controls. A large number of these genes were associated with the mTOR signaling pathway. The differentially expressed genes involved in the mTOR signaling pathway were verified further, as well as their downstream genes associated with autophagy. The results of the present study provided an insight into the potential inhibitory mechanism of isatin on neuroblastoma metastasis.

A curcumin derivative, WZ35, suppresses hepatocellular cancer cell growthviadownregulating YAP-mediated autophagy

HCC is a common cancer type in the world. Here, we found WZ35, a novel derivative of curcumin, could notably suppress HCC cell growthviainhibiting YAP controlled autophagy, highlighting the potent anti-tumor activity of WZ35 in liver cancer therapy.

Comparative toxicity evaluation of targeted anticancer therapeutics in embryonic zebrafish and sea urchin models

Cancer drug resistance and poor selectivity towards cancer cells demand the constant search for new therapeutics. PI3K-Akt-mTOR and RAS-MAPK-ERK signaling pathways are key mechanisms involved in cell survival, proliferation, differentiation, and metabolism and their deregulation in cancer can promote development of therapy resistance. We investigated the effects of targeted inhibitors (wortmannin, GSK690693, AZD2014 and tipifarnib) towards these two pathways on early zebrafish and sea urchin development to assess their toxicity in normal, fast proliferating cells. PI3K inhibitor wortmannin and RAS inhibitor tipifarnib displayed highest toxicity while GSK690693, a pan-Akt kinase inhibitor, exhibited a less significant impact on embryo survival and development. Moreover, inhibition of the upstream part of the PI3K-Akt-mTOR pathway (wortmannin/GSK690693 co-treatment) produced a synergistic effect and impacted zebrafish embryo survival and development at much lower concentrations. Dual mTORC1/mTORC2 inhibitor AZD2014 showed no considerable effects on embryonic cells of zebrafish in concentrations substantially toxic in cancer cells. AZD2014 also caused the least prominent effects on sea urchin embryo development compared to other inhibitors. Significant toxicity of AZD2014 in human cancer cells, its capacity to sensitize resistant cancers, lower antiproliferative activity against human normal cell lines and fast proliferating embryonic cells could make this agent a promising candidate for anticancer therapy.