Chloroquine affects autophagy to achieve an anticancer effect in EC109 esophageal carcinoma cells in vitro

Construction of a Multifunctional Upconversion Nanoplatform Based on Autophagy Inhibition and Photodynamic Therapy Combined with Chemotherapy for Antitumor Therapy

Inhibition of autophagy increases the sensitivity of tumor cells to radiotherapy and chemotherapy and improves the therapeutic effect on tumors. Recently, photodynamic therapy (PDT) combined with chemotherapy has been proven to further improve the efficiency of cancer treatment. As such, combining autophagy inhibition with PDT and chemotherapy may represent a potentially effective new strategy for cancer treatment. However, currently widely studied autophagy inhibitors inevitably produce various toxic side effects due to their inherent pharmacological activity. To overcome this constraint, in this study, we designed an ideal multifunctional upconversion nanoplatform, UCNP-Ce6-EPI@mPPA + NIR (MUCEN). Control, UCNP-EPI@mPPA (MUE), UCNP-EPI@mPPA + NIR (MUEN), Ce6-EPI@mPPA (MCE), Ce6-EPI@mPPA + NIR (MCEN), and UCNP-Ce6-EPI@mPPA (MUCE) groups were set up separately as controls. Based on a combination of autophagy inhibition and PDT, the average particle size of MUCEN was 197 nm, which can simultaneously achieve the double encapsulation of chlorine e6 (Ce6) and epirubicin (EPI). In vitro tests revealed that MUCE was efficiently endocytosed by 4T1 cells under near-infrared light irradiation. Further, in vivo tests revealed that MUCE dramatically inhibited tumor growth. Immunohistochemistry results indicated that MUCE efficiently increased the expression of autophagy inhibitors p62 and LC3 in tumor tissues. The synergistic effect of autophagy inhibition and PDT with MUCE exhibited superior tumor suppression, providing an innovative approach to cancer treatment.

Chloroquine Sensitizes Esophageal Carcinoma EC109 Cells to Paclitaxel by Inhibiting Autophagy

As an autophagy inhibitor, chloroquine (CQ) showed anti-tumor effect on several types of cancer and paclitaxel (PTX) is widely used in the treatment of esophageal carcinoma patients, but chemoresistance remains a major hurdle for PTX application due to the cytoprotective autophagy. Therefore, the aim of this study was to investigate whether CQ could elevate the anti-tumor effect of PTX on esophageal carcinoma cell line EC109 and explore the potential molecular mechanisms. We confirmed the suppressive effect of PTX on EC109 by MTT, scratch test, transwell and soft agar assay. And, we detected the key proteins in Akt/mTOR pathway, as well as the autophagy marker LC3 and p62 through Western Blot. In addition, GFP-LC3 plasmid was transfected into EC109 cells to monitor the autophagosome after CQ and PTX treatment. Ultimately, we observed the alterations in the proliferation and colony formation abilities of EC109 after knocking down mTOR by shRNA. We confirmed PTX could suppress the proliferation, migration and colony formation (all P < 0.05) abilities of EC109, and CQ could sensitize the inhibition effect of PTX by inhibiting autophagy through Akt/mTOR pathway. Furthermore, inhibiting Akt/mTOR pathway initiated autophagy and enhanced the sensitivity of EC109 to CQ and PTX. In summary, we suggest CQ could be used as a potential chemosensitizer for PTX in esophageal carcinoma treatment.

An Alternative Autophagy-Related Mechanism of Chloroquine Drug Resistance in the Malaria Parasite

We generated highly chloroquine (CQ)-resistant (ResCQ) Plasmodium yoelii parasites by stepwise exposure to increasing concentrations of CQ and CQ-sensitive parasites (SenCQ) by parallel mock treatments. No mutations in genes that are associated with drug resistance were detected in ResCQ clones. Autophagy-related genes were highly upregulated in SenCQ compared to ResCQ parasites during CQ treatment. This indicates that CQ resistance can be developed in the malaria parasite by the inhibition of autophagy as an alternative drug resistance mechanism.

Chloroquine regulates the proliferation and apoptosis of palate development on mice embryo by activating P53 through blocking autophagy in vitro

Cleft lip and palate is one of the most frequent congenital developmental defects. Autophagy is a highly conserved process of cell self-degradation in eukaryotes, involving multiple biological processes in which chloroquine (CQ) is the most common inhibitor. However, whether CQ affects and how it affects palate development is unknown. Mouse embryonic palatal cells (MEPCs) were treated with CQ to observe cell viability, apoptosis, migration, osteogenic differentiation by cell proliferation assay, flow cytometric analysis, scratch assay, and alizarin red staining. PI staining was used to measure cell cycle distribution. Immunofluorescence (IF) assay and transmission electron microscopy were used to detect autophagosomes. The autophagy-related factors (LC3 and P62), apoptosis-related markers (P53, caspase-3 cleaved caspase-3, BAX, and BCL-2), and cell cycle-related proteins (P21, CDK2, CDK4, cyclin D1, and cyclin E) were all measured by western blot. CQ inhibited the proliferation of MEPCs by arresting the G0/G1 phase of the cell cycle in a concentration- and time-dependent manner with cell cycle-related proteins P21 upregulated and CDK2, CDK4, cyclin D1, and cyclin E downregulated. Then we detected CQ also induced cell apoptosis in a dose-dependent manner by decreasing the BCL-2/BAX ratio and increasing cleaved caspase-3. Next, it was investigated that migration and osteogenesis of MEPCs decreased with CQ treatment in a dose-dependent manner. Meanwhile, CQ blocked the autophagy pathway by upregulating LC3II and P62 expressions which activated the P53 pathway. CQ activates P53 which affects MEPC biological characteristics by changing the proliferation and apoptosis of MEPCs through inhibiting autophagy.

Extracellular DNA Traps: Origin, Function and Implications for Anti-Cancer Therapies

Extracellular DNA may serve as marker in liquid biopsies to determine individual diagnosis and prognosis in cancer patients. Cell death or active release from various cell types, including immune cells can result in the release of DNA into the extracellular milieu. Neutrophils are important components of the innate immune system, controlling pathogens through phagocytosis and/or the release of neutrophil extracellular traps (NETs). NETs also promote tumor progression and metastasis, by modulating angiogenesis, anti-tumor immunity, blood clotting and inflammation and providing a supportive niche for metastasizing cancer cells. Besides neutrophils, other immune cells such as eosinophils, dendritic cells, monocytes/macrophages, mast cells, basophils and lymphocytes can also form extracellular traps (ETs) during cancer progression, indicating possible multiple origins of extracellular DNA in cancer. In this review, we summarize the pathomechanisms of ET formation generated by different cell types, and analyze these processes in the context of cancer. We also critically discuss potential ET-inhibiting agents, which may open new therapeutic strategies for cancer prevention and treatment.

A Review: PI3K/AKT/mTOR Signaling Pathway and Its Regulated Eukaryotic Translation Initiation Factors May Be a Potential Therapeutic Target in Esophageal Squamous Cell Carcinoma

Esophageal squamous cell carcinoma (ESCC) is a malignant tumor developing from the esophageal squamous epithelium, and is the most common histological subtype of esophageal cancer (EC). EC ranks 10th in morbidity and sixth in mortality worldwide. The morbidity and mortality rates in China are both higher than the world average. Current treatments of ESCC are surgical treatment, radiotherapy, and chemotherapy. Neoadjuvant chemoradiotherapy plus surgical resection is recommended for advanced patients. However, it does not work in the significant promotion of overall survival (OS) after such therapy. Research on targeted therapy in ESCC mainly focus on EGFR and PD-1, but neither of the targeted drugs can significantly improve the 3-year and 5-year survival rates of disease. Phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway is an important survival pathway in tumor cells, associated with its aggressive growth and malignant progression. Specifically, proliferation, apoptosis, autophagy, and so on. Related genetic alterations of this pathway have been investigated in ESCC, such as PI3K, AKT and mTOR-rpS6K. Therefore, the PI3K/AKT/mTOR pathway seems to have the capability to serve as research hotspot in the future. Currently, various inhibitors are being tested in cells, animals, and clinical trials, which targeting at different parts of this pathway. In this work, we reviewed the research progress on the PI3K/AKT/mTOR pathway how to influence biological behaviors in ESCC, and discussed the interaction between signals downstream of this pathway, especially eukaryotic translation initiation factors (eIFs) and the development and progression of ESCC, to provide reference for the identification of new therapeutic targets in ESCC.

Differences in Cellular Clearing Mechanisms of Aggregates of Two Subtypes of HLA-B27

Ankylosing spondylitis (AS) belongs to a group of diseases, called spondyloarthropathies (SpA), that are strongly associated with the genetic marker HLA-B27. AS is characterized by inflammation of joints and primarily affects the spine. Over 160 subtypes of HLA-B27 are known, owing to high polymorphism. Some are strongly associated with disease (e.g., B*2704), whereas others are not (e.g., B*2709). Misfolding of HLA-B27 molecules [as dimers, or as high-molecular-weight (HMW) oligomers] is one of several hypotheses proposed to explain the link between HLA-B27 and AS. Our group has previously established the existence of HMW species of HLA-B27 in AS patients. Still, very little is known about the mechanisms underlying differences in pathogenic outcomes of different HLA-B27 subtypes. We conducted a proteomics-based evaluation of the differential disease association of HLA B*2704 and B*2709, using stable transfectants of genes encoding the two proteins. A clear difference was observed in protein clearance mechanisms: whereas unfolded protein response (UPR), autophagy, and aggresomes were involved in the degradation of B*2704, the endosome–lysosome machinery was primarily involved in B*2709 degradation. These differences offer insights into the differential disease association of B*2704 and B*2709.

Therapeutic Approach of KRAS Mutant Tumours by the Combination of Pharmacologic Ascorbate and Chloroquine

The Warburg effect has been considered a potential therapeutic target to fight against cancer progression. In KRAS mutant cells, PKM2 (pyruvate kinase isozyme M2) is hyper-activated, and it induces GLUT1 expression; therefore, KRAS has been closely involved in the initiation of Warburg metabolism. Although mTOR (mammalian target of rapamycin), a well-known inhibitor of autophagy-dependent survival in physiological conditions, is also activated in KRAS mutants, many recent studies have revealed that autophagy becomes hyper-active in KRAS mutant cancer cells. In the present study, a mathematical model was built containing the main elements of the regulatory network in KRAS mutant cancer cells to explore the further possible therapeutic strategies. Our dynamical analysis suggests that the downregulation of KRAS, mTOR and autophagy are crucial in anti-cancer therapy. PKM2 has been assumed to be the key switch in the stress response mechanism. We predicted that the addition of both pharmacologic ascorbate and chloroquine is able to block both KRAS and mTOR pathways: in this case, no GLUT1 expression is observed, meanwhile autophagy, essential for KRAS mutant cancer cells, is blocked. Corresponding to our system biological analysis, this combined pharmacologic ascorbate and chloroquine treatment in KRAS mutant cancers might be a therapeutic approach in anti-cancer therapies.

Chloroquine Inhibits Stemness of Esophageal Squamous Cell Carcinoma Cells Through Targeting CXCR4-STAT3 Pathway

Esophageal squamous cell carcinoma (ESCC) is one of the most prevalent cancers worldwide. Recent studies have shown that cancer stem cells (CSCs) are present in ESCC, are thought to lead to aggressive tumor behavior and the prognosis. The CXC chemokine receptor 4 (CXCR4), is regarded as a putative CSCs marker in various malignancies. Here, we demonstrate that CXCR4 played a key role in ESCC progression and CXCR4 positive ESCC cells possessed stem-like properties. Furthermore, the anti-malarial agent chloroquine (CQ) targeted CXCR4-positive ESCC cells via STAT3 pathway. Therefore, CQ with anti-CSCs effects may be an effective adjunct to current ESCC chemotherapy regimens.

The Role of Autophagy in the Resistance to BRAF Inhibition in BRAF-Mutated Melanoma

Malignant melanoma is the most aggressive and notorious skin cancer, and metastatic disease is associated with very poor long-term survival outcomes. Although metastatic melanoma patients with oncogenic mutations in the BRAF gene initially respond well to the treatment with specific BRAF inhibitors, most of them will eventually develop resistance to this targeted therapy. As a highly conserved catabolic process, autophagy is responsible for the maintenance of cellular homeostasis and cell survival, and is involved in multiple diseases, including cancer. Recent study results have indicated that autophagy might play a decisive role in the resistance to BRAF inhibitors in BRAF-mutated melanomas. In this review, we will discuss how autophagy is up-regulated by BRAF inhibitors, and how autophagy induces the resistance to these agents.

In Situ Autophagy Disruption Generator for Cancer Theranostics

Cancer remains a serious clinical disease awaiting new effective treatment strategies. Autophagy modulation has emerged as a novel and promising pharmacologic target critical to future drug development and anti-cancer therapy applications. Herein, we constructed an in situ autophagy disruption generator to break the balance of autophagy flow for tumor-targeting therapy. Hollow mesoporous manganese trioxide (Mn₂O₃) nanoparticles (NPs) were synthesized and conjugated with hyaluronic acid (HA) to form tumor-targeting drug carriers. Then, traditional autophagy inhibitor hydroxychloroquine (HCQ) was loaded into the hollow core of HA-Mn₂O₃, to form a multifunctional theranostics platform (HA-Mn₂O₃/HCQ). This nanoplatform displayed specific localization and retention in lysosomes after entering tumor cells. The synchronous release of HCQ and manganese ion (Mn²⁺) induced lysosomal alkalization and osmotic pressure elevation. Significantly greater lysosomal deacidification and autophagy blockade effect emerged after treatment by this nanoplatform, with in vitro tumor inhibition rate of 92.2%. Imaging experiment proved that it could selectively deliver HCQ to tumor sites and further degrade to realize simultaneous release of Mn²⁺ and HCQ. Micromorphological and immunofluorescence analysis demonstrated that in situ high concentrations of these two substances would achieve effective autophagy blockade. Pharmacodynamics test showed that this nanogenerator displayed the best therapeutic efficacy with 5.08-fold tumor inhibition ratio compared with the HCQ group. Moreover, the generated Mn²⁺ can be used as T1 contrast agent for visualizing tumor lesions and monitoring therapeutic effects. Overall, the as-made multifunctional drug-delivery system might provide a promising platform for cancer theranostics upon in situ autophagy disruption.