CXCR4-mediated signaling regulates autophagy and influences acute myeloid leukemia cell survival and drug resistance

CXCR4 as a therapeutic target in acute myeloid leukemia

Extensive research on the CXCL12-CXCR4 axis in acute myeloid leukemia (AML) has resulted in the incorporation of novel anti-leukemia drugs targeting this axis into therapeutic strategies. However, despite this progress, a comprehensive and up-to-date review addressing the role of the CXCL12-CXCR4 axis in AML's oncogenic processes is lacking. In this review, we examine its molecular aspects influencing cancer progression, such as its impact on autonomous proliferation, apoptotic regulation, chemoresistance mechanisms, and interactions with non-leukemic cells such as MSCs and Treg cells. Additionally, we explore clinical implications, including prognosis, correlation with WBC count, blast count in the bone marrow and peripheral blood, as well as its association with FLT3-ITD, NPM1 mutations, and FAB classification. Finally, this paper extensively discusses drugs that specifically target the CXCL12-CXCR4 axis, including plerixafor/AMD3100, ulocuplumab, peptide E5, and motixafortide, shedding light on their potential therapeutic value in the treatment of AML.

Luteolin Protects against Vascular Calcification by Modulating SIRT1/CXCR4 Signaling Pathway and Promoting Autophagy

Vascular calcification (VC) is a common pathological manifestation of atherosclerosis, hypertension, diabetes vascular disease, vascular injury, chronic kidney disease and aging, which is mainly manifested as increased stiffness of the vascular wall. Oxidative stress and autophagy dysfunction are key factors in the pathogenesis of vascular calcification, but the specific mechanisms and the therapeutic strategy of vascular calcification have not been clarified. In the present study, Sirtuin 1 (SIRT1) was screened as the therapeutic targets for vascular calcification by the bioinformatics. SIRT1 is a nicotinamide adenine dinucleotide, which plays an important role in inhibiting oxidative stress and promoting autophagy. Luteolin (LUT), a kind of natural tetrahydroxyl flavonoid, exists in many plants and has many pharmacological effects such as anti-oxidation and anti-apoptosis. We have reported that luteolin has certain anti-osteoporosis effects in the previous study, and it is accepted that the development of vascular calcification is similar to bone formation, indicating that luteolin may also resist vascular calcification. And luteolin is known to activate SIRT1 to some extent. Moreover, the molecular docking analysis predicted that SIRT1 could bind directly to luteolin. Therefore, the purpose of this study was to investigate the potential role of luteolin in inhibiting oxidative stress and promoting autophagy during vascular calcification via modulating SIRT1 expression. The results showed that luteolin significantly improved vascular calcification induced by a high-fat diet (HFD) and vitamin D3 in rats in vivo. In addition, luteolin significantly repressed the formation of mineralized nodules and ALP activity in H2O2-treated A7r5 cells. Luteolin reduced the level of MDA, LDH and ROS generation, inhibited the protein expression of cleaved caspase-3, cleaved caspase-9, β-catenin and BMP-2 in the aortic tissue of the rat and rat smooth muscle cells (A7r5) treated with hydrogen peroxide. At the same time, luteolin could promote the expression of autophagy related proteins. Moreover, luteolin also produced effects to increase the protein expression levels of SIRT1 more than 2 times both in vivo and in vitro. In terms of mechanism, luteolin attenuated vascular calcification by inhibiting oxidative stress and improving autophagy level, via modulating SIRT1 / CXCR4 signaling pathway. In conclusion, this experiment for the first time revealed that LUT protected against VC via modulating SIRT1 / CXCR4 signaling pathway to promote autophagy and inhibit vascular calcification and may be developed as a new therapeutic agent for vascular calcification and atherosclerosis.

The Role of SIRT1 in Leukemia

OPINION STATEMENT

Leukemia is a type of hematological malignancy (HM) caused by uncontrolled proliferation, apoptosis, and differentiation of hematopoietic stem cells (HSCs). Leukemia cells proliferate greatly in the bone marrow (BM), infiltrate other tissues and organs, and affect the normal hematopoietic function. Although the emergence of new targeted agents and immune agents has improved the prognosis of patients, due to the complex pathogenic factors and heterogeneity of leukemia, there are still some patients with poor prognosis. Recent studies have shown that silent information regulator 1 (SIRT1) is involved in the proliferation, apoptosis, metabolism, and senescence of leukemia cells. As a double-edged sword in leukemia cells, SIRT1 can both promote and inhibit the growth of leukemia cells. Since its mechanism of action has not been elucidated, it is urgent to explore the regulatory mechanism of SIRT1 in leukemia. In this review, we discussed the mechanisms of SIRT1 in different aspects of leukemia, providing a theoretical basis for the treatment of patients with leukemia.

Progress in the study of autophagy-related proteins affecting resistance to chemotherapeutic drugs in leukemia

Leukemia is a life-threatening malignant tumor of the hematopoietic system. Currently, the main treatment modalities are chemotherapy and hematopoietic stem cell transplantation. However, increased drug resistance due to decreased sensitivity of leukemia cells to chemotherapeutic drugs presents a major challenge in current treatments. Autophagy-associated proteins involved in autophagy initiation have now been shown to be involved in the development of various types of leukemia cells and are associated with drug resistance. Therefore, this review will explore the roles of autophagy-related proteins involved in four key autophagic processes: induction of autophagy and phagophore formation, phagophore extension, and autophagosome formation, on the development of various types of leukemias as well as drug resistance. Autophagy may become a promising therapeutic target for treating leukemia.

General anaesthetics reduce acute lymphoblastic leukaemia malignancies in vitro and in vivovia CXCR4 and osteopontin mediated mechanisms

Background

Acute lymphoblastic leukaemia (ALL) is a common type of cancer in children. General anaesthetics are often used on patients undergoing painful procedures during ALL treatments but their effects on ALL malignancy remain unknown. Herein, we aim to study the effect of propofol and sevoflurane on the migration, homing and chemoresistance of ALL cells.

Methods

NALM-6 and Reh cells were treated with propofol (5 and 10 μg/ml) or sevoflurane (3.6%) in vitro for six hours. Then, cells were harvested for adhesion assay and migration assay in vitro. In in vivo experiments, GFP-NALM-6 cells were pre-treated with propofol (10 μg/ml) or sevoflurane (3.6%) for six hours. Then, cells were injected intravenously to C57BL/6 female mice followed by intravital microscopy. For chemoresistance study, cells were treated with rising concentrations of Ara-c (0.05-50 nM) plus 10μg/ml of propofol or Ara-C plus 3.6% of sevoflurane for 4 hours, followed by the assessment of cell viability via CCK-8 assay and detection of autophagy via flow cytometry.

Results

Both anaesthetics reduced in vivo migration and in vivo homing as exemplified by 1) the reduction in the number of cells entering the bone marrow and 2) the disturbance in homing location in relation to endosteal surface. Our results indicated that general anaesthetics reduced the surface CXCR4 expression and the adhesion of leukaemia cells to thrombin cleaved osteopontin (OPN) was reduced. Those changes might result in the alterations in migration and homing. In addition, both anaesthetics sensitised ALL cells to Ara-c possibly through CXCR4 mediated mechanisms. Propofol but not sevoflurane enhanced chemo-related cell death via inducing cytotoxic autophagy.

Conclusion

Together, our data suggest that both propofol and sevoflurane could reduce ALL migration, and homing in vivo and in vitro via CXCR4 and OPN mediated mechanisms. Both anaesthetics could sensitise ALL cells to chemotherapy possibly via CXCR4 mediated mechanisms.

Unveiling autophagy complexity in leukemia: The molecular landscape and possible interactions with apoptosis and ferroptosis

Autophagy is a self-digestion multistep process in which causes the homeostasis through degradation of macromolecules and damaged organelles. The autophagy-mediated tumor progression regulation has been a critical point in recent years, revealing the function of this process in reduction or acceleration of carcinogenesis. Leukemia is a haematological malignancy in which abnormal expansion of hematopoietic cells occurs. The current and conventional therapies from chemotherapy to cell transplantation have failed to appropriately treat the leukemia patients. Among the mechanisms dysregulated in leukemia, autophagy is a prominent one in which can regulate the hallmarks of this tumor. The protective autophagy inhibits apoptosis and ferroptosis in leukemia, while toxic autophagy accelerates cell death. The proliferation and invasion of tumor cells are tightly regulated by the autophagy. The direction of regulation depends on the function of autophagy that is protective or lethal. The protective autophagy accelerates chemoresistance and radio-resistsance. The non-coding RNAs, histone transferases and other pathways such as PI3K/Akt/mTOR are among the regulators of autophagy in leukemia progression. The pharmacological intervention for the inhibition or induction of autophagy by the compounds including sesamine, tanshinone IIA and other synthetic compounds can chance progression of leukemia.

Crosstalk between autophagy and metabolism: implications for cell survival in acute myeloid leukemia

Acute myeloid leukemia (AML), a prevalent form of leukemia in adults, is often characterized by low response rates to chemotherapy, high recurrence rates, and unfavorable prognosis. A critical barrier in managing refractory or recurrent AML is the resistance to chemotherapy. Increasing evidence indicates that tumor cell metabolism plays a crucial role in AML progression, survival, metastasis, and treatment resistance. Autophagy, an essential regulator of cellular energy metabolism, is increasingly recognized for its role in the metabolic reprogramming of AML. Autophagy sustains leukemia cells during chemotherapy by not only providing energy but also facilitating rapid proliferation through the supply of essential components such as amino acids and nucleotides. Conversely, the metabolic state of AML cells can influence the activity of autophagy. Their mutual coordination helps maintain intrinsic cellular homeostasis, which is a significant contributor to chemotherapy resistance in leukemia cells. This review explores the recent advancements in understanding the interaction between autophagy and metabolism in AML cells, emphasizing their roles in cell survival and drug resistance. A comprehensive understanding of the interplay between autophagy and leukemia cell metabolism can shed light on leukemia cell survival strategies, particularly under adverse conditions such as chemotherapy. This insight may also pave the way for innovative targeted treatment strategies.

Role of SIRT1 in Chemoresistant Leukemia

Leukemias of the AML, CML, and CLL types are the most common blood cancers worldwide, making them a major global public health problem. Furthermore, less than 24% of patients treated with conventional chemotherapy (low-risk patients) and 10-15% of patients ineligible for conventional chemotherapy (high-risk patients) survive five years. The low levels of survival are mainly due to toxicity and resistance to chemotherapy or other medication, the latter leading to relapse of the disease, which is the main obstacle to the treatment of leukemia. Drug resistance may include different molecular mechanisms, among which epigenetic regulators are involved. Silent information regulator 2 homolog 1 (SIRT1) is an epigenetic factor belonging to the sirtuin (SIRT) family known to regulate aspects of chromatin biology, genome stability, and metabolism, both in homeostasis processes and in different diseases, including cancer. The regulatory functions of SIRT1 in different biological processes and molecular pathways are dependent on the type and stage of the neoplasia; thus, it may act as both an oncogenic and tumor suppressor factor and may also participate in drug resistance. In this review, we explore the role of SIRT1 in drug-resistant leukemia and its potential as a therapeutic target.

Inhibition of Dipeptidyl Peptidase-4 Activates Autophagy to Promote Survival of Breast Cancer Cells via the mTOR/HIF-1α Pathway

Autophagy plays a complex role in breast cancer cell survival, metastasis, and chemotherapeutic resistance. Dipeptidyl peptidase (DPP)-4, a therapeutic target for type 2 diabetes mellitus, is also involved in autophagic flux. The potential influence of DPP-4 suppression on cancer biology remains unknown. Here, we report that DPP-4 deficiency promotes breast cancer cell survival via the induction of autophagy by the C-X-C motif chemokine 12 (CXCL12)/C-X-C receptor 4 (CXCR4)/mammalian target of rapamycin (mTOR)/hypoxia inducible factor (HIF)-1α axis. DPP-4 knockdown and DPP-4 inhibitor KR62436 (KR) treatment both increased the levels of LC3II and HIF-1α in cultured human breast and mouse mammary cancer cells. The KR-induced autophagic phenotype in cancer cells was inhibited by treatment with the CXCR4 inhibitor AMD3100 and rapamycin. HIF-1α knockdown also suppressed breast cancer autophagy induced by KR. The autophagy inhibitor 3-methyladenine significantly blocked the KR-mediated suppression of cleaved caspase-3 levels and apoptosis in breast cancer cell lines. Finally, we found that the metformin-induced apoptosis of DPP-4-deficient 4T1 mammary cancer cells was associated with the suppression of autophagy. Our findings identify a novel role for DPP-4 inhibition in the promotion of breast cancer survival by inducing CXCL12/CXCR4/mTOR/HIF-1α axis-dependent autophagy. Metformin is a potential drug that counteracts the breast cancer cell survival system.

Advances in Understanding the Links between Metabolism and Autophagy in Acute Myeloid Leukemia: From Biology to Therapeutic Targeting

Autophagy is a highly conserved cellular degradation process that regulates cellular metabolism and homeostasis under normal and pathophysiological conditions. Autophagy and metabolism are linked in the hematopoietic system, playing a fundamental role in the self-renewal, survival, and differentiation of hematopoietic stem and progenitor cells, and in cell death, particularly affecting the cellular fate of the hematopoietic stem cell pool. In leukemia, autophagy sustains leukemic cell growth, contributes to survival of leukemic stem cells and chemotherapy resistance. The high frequency of disease relapse caused by relapse-initiating leukemic cells resistant to therapy occurs in acute myeloid leukemia (AML), and depends on the AML subtypes and treatments used. Targeting autophagy may represent a promising strategy to overcome therapeutic resistance in AML, for which prognosis remains poor. In this review, we illustrate the role of autophagy and the impact of its deregulation on the metabolism of normal and leukemic hematopoietic cells. We report updates on the contribution of autophagy to AML development and relapse, and the latest evidence indicating autophagy-related genes as potential prognostic predictors and drivers of AML. We review the recent advances in autophagy manipulation, combined with various anti-leukemia therapies, for an effective autophagy-targeted therapy for AML.

SDF-1α Promotes Chondrocyte Autophagy through CXCR4/mTOR Signaling Axis

SDF-1α, the most common isoform of stromal cell-derived factor 1, has shown vital effects in regulating chondrocyte proliferation, maturation, and chondrogenesis. Autophagy is a highly conserved biological process to help chondrocytes survive in harsh environments. However, the effect of SDF-1α on chondrocyte autophagy is still unknown. This study aims to investigate the effect of SDF-1α on chondrocyte autophagy and the underlying biomechanism. Transmission electron microscope assays and mRFP-GFP-LC3 adenovirus double label transfection assays were performed to detect the autophagic flux of chondrocytes. Western blots and immunofluorescence staining assays were used to detect the expression of autophagy-related proteins in chondrocytes. RNA sequencing and qPCR were conducted to assess changes in autophagy-related mRNA expression. SDF-1α upregulated the number of autophagosomes and autolysosomes in chondrocytes. It also increased the expression of autophagy-related proteins including ULK-1, Beclin-1 and LC3B, and decreased the expression of p62, an autophagy substrate protein. SDF-1α-mediated autophagy of chondrocytes required the participation of receptor CXCR4. Moreover, SDF-1α-enhanced autophagy of chondrocytes was through the inhibition of phosphorylation of mTOR signaling on the upstream of autophagy. Knockdown by siRNA and inhibition by signaling inhibitor further confirmed the importance of the CXCR4/mTOR signaling axis in SDF-1α-induced autophagy of chondrocytes. For the first time, this study elucidated that SDF-1α promotes chondrocyte autophagy through the CXCR4/mTOR signaling axis.

Autophagy and Its Lineage-Specific Roles in the Hematopoietic System

Autophagy is a dynamic process that regulates the selective and nonselective degradation of cytoplasmic components, such as damaged organelles and protein aggregates inside lysosomes to maintain tissue homeostasis. Different types of autophagy including macroautophagy, microautophagy, and chaperon-mediated autophagy (CMA) have been implicated in a variety of pathological conditions, such as cancer, aging, neurodegeneration, and developmental disorders. Furthermore, the molecular mechanism and biological functions of autophagy have been extensively studied in vertebrate hematopoiesis and human blood malignancies. In recent years, the hematopoietic lineage-specific roles of different autophagy-related (ATG) genes have gained more attention. The evolution of gene-editing technology and the easy access nature of hematopoietic stem cells (HSCs), hematopoietic progenitors, and precursor cells have facilitated the autophagy research to better understand how ATG genes function in the hematopoietic system. Taking advantage of the gene-editing platform, this review has summarized the roles of different ATGs at the hematopoietic cell level, their dysregulation, and pathological consequences throughout hematopoiesis.

Functions and clinical significance of circular RNAs in acute myeloid leukemia

Circular RNAs (circRNAs) are a class of covalently closed single-stranded RNA molecules. Four types of circRNAs have been reported in animal cells, and they have typical characteristics in their biogenesis, nuclear export and degradation. Advances in our understanding of the molecular functions of circRNAs in sponging microRNAs, modulating transcription, regulating RNA-binding proteins, as well as encoding proteins have been made very recently. Dysregulated circRNAs are associated with human diseases such as acute myeloid leukemia (AML). In this review, we focus on the recently described mechanisms, role and clinical significance of circRNAs in AML. Although great progress of circRNAs in AML has been achieved, substantial efforts are still required to explore whether circRNAs exert their biological function by other mechanisms such as regulation of gene transcription or serving as translation template in AML. It is also urgent that researchers study the machineries regulating circRNAs fate, the downstream effectors of circRNAs modulatory networks, and the clinical application of circRNAs in AML.

Potential role of autophagy induced by FLT3-ITD and acid ceramidase in acute myeloid leukemia chemo-resistance: new insights

Acute myeloid leukemia (AML) is a type of leukemia with a poor prognosis and survival characterized by abnormal cell proliferation and differentiation. Despite advances in treatment, AML still has a low complete remission rate, particularly in elderly patients, and recurrences are frequently seen even after complete remissions. The major challenge in treating AML is the resistance of leukemia cells to chemotherapy drugs. Thus, to overcome this issue, it can be crucial to conduct new investigations to explore the mechanisms of chemo-resistance in AML and target them. In this review, the potential role of autophagy induced by FLT3-ITD and acid ceramidase in chemo-resistance in AML patients are analyzed. With regard to the high prevalence of FLT3-ITD mutation (about 25% of AML cases) and high level of acid ceramidase in these patients, we hypothesized that both of these factors could lead to chemo-resistance by inducing autophagy. Therefore, pharmacological targeting of autophagy, FLT3-ITD, and acid ceramidase production could be a promising therapeutic approach for such AML patients to overcome chemo-resistance.

Autophagy in Hematological Malignancies

Simple Summary

Autophagy is a dynamic and tightly regulated process that seems to have dual effects in cancer. In some contexts, it can induce carcinogenesis and promote cancer cell survival, whereas in others, it acts preventing tumor cell growth and tumor progression. Thus, autophagy functions seem to strictly depend on cancer ontogenesis, progression, and type. Here, we will dive into the current knowledge of autophagy in hematological malignancies and will highlight the main genetic components involved in each cancer type.

Abstract

Autophagy is a highly conserved metabolic pathway via which unwanted intracellular materials, such as unfolded proteins or damaged organelles, are digested. It is activated in response to conditions of oxidative stress or starvation, and is essential for the maintenance of cellular homeostasis and other vital functions, such as differentiation, cell death, and the cell cycle. Therefore, autophagy plays an important role in the initiation and progression of tumors, including hematological malignancies, where damaged autophagy during hematopoiesis can cause malignant transformation and increase cell proliferation. Over the last decade, the importance of autophagy in response to standard pharmacological treatment of hematological tumors has been observed, revealing completely opposite roles depending on the tumor type and stage. Thus, autophagy can promote tumor survival by attenuating the cellular damage caused by drugs and/or stabilizing oncogenic proteins, but can also have an antitumoral effect due to autophagic cell death. Therefore, autophagy-based strategies must depend on the context to create specific and safe combination therapies that could contribute to improved clinical outcomes. In this review, we describe the process of autophagy and its role on hematopoiesis, and we highlight recent research investigating its role as a potential therapeutic target in hematological malignancies. The findings suggest that genetic variants within autophagy-related genes modulate the risk of developing hemopathies, as well as patient survival.

The dual role of autophagy in acute myeloid leukemia

Acute myeloid leukemia (AML) is a severe hematologic malignancy prevalent in older patients, and the identification of potential therapeutic targets for AML is problematic. Autophagy is a lysosome-dependent catabolic pathway involved in the tumorigenesis and/or treatment of various cancers. Mounting evidence has suggested that autophagy plays a critical role in the initiation and progression of AML and anticancer responses. In this review, we describe recent updates on the multifaceted functions of autophagy linking to genetic alterations of AML. We also summarize the latest evidence for autophagy-related genes as potential prognostic predictors and drivers of AML tumorigenesis. We then discuss the crosstalk between autophagy and tumor cell metabolism into the impact on both AML progression and anti-leukemic treatment. Moreover, a series of autophagy regulators, i.e., the inhibitors and activators, are described as potential therapeutics for AML. Finally, we describe the translation of autophagy-modulating therapeutics into clinical practice. Autophagy in AML is a double-edged sword, necessitating a deeper understanding of how autophagy influences dual functions in AML tumorigenesis and anti-leukemic responses.

Autophagy in acute myeloid leukemia: a paradoxical role in chemoresistance

Autophagy is a lysosomal degradation pathway that is constitutively active in almost every cell of our body at basal level. This self-eating process primarily serves to remove superfluous constituents of the cells and recycle the degraded products. Autophagy plays an essential role in cell homeostasis and can be enhanced in response to stressful conditions. Impairment in the regulation of the autophagic pathway is implicated in pathological conditions such as neurodegeneration, cardiac disorders, and cancer. However, the role of autophagy in cancer initiation and development is controversial and context-dependent. Evidence from various studies has shown that autophagy serves dual purpose and may assist in cancer progression or suppression. In the early stages of cancer initiation, autophagy acts as a quality control mechanism and prevents cancer development. When cancer is established and progresses to a later stage, autophagy helps in the survival of these cells through adaptation to stresses, including exposure to anti-cancer drugs. In this review, we highlight various studies on autophagic pathways and describe the role of autophagy in cancer, specifically acute myeloid leukemia (AML). We also discuss the prognostic significance of autophagy genes involved in AML leukemogenesis and implications in conferring resistance to chemotherapy.

SIRT1-SIRT7 Expression in Patients with Lymphoproliferative Disorders Undergoing Hematopoietic Stem Cell Mobilization

Sirtuins are involved in the fate of hematopoietic stem cells (HSCs), including their metabolism, stress response, differentiation, migration, and apoptosis. The aim of this study was to explore SIRT1-7 expression during HSC mobilization. The study included 50 patients with lymphoproliferative disorders (39 multiple myeloma, 11 lymphoma). Samples were taken before mobilization (day 0) and on the day of first apheresis (day A). The sirtuin expression was evaluated by the Droplet Digital PCR (ddPCR) method. A significant increase of the SIRT1, SIRT2, SIRT3, SIRT5, SIRT6, and SIRT7 levels measured at day A as compared to baseline was observed. The study revealed a positive correlation between SIRT5, SIRT6, and SIRT7 expression and the CD34+ peak value in peripheral blood and the number of CD34+ cells collected on day A. Patients from the SIRT7 “high expressors” group collected more CD34+ cells on day A than “low expressors”. Upregulated expressions of SIRT3 and SIRT7 on the day of first apheresis were observed in patients in complete remission status (CR) as compared to the non-CR group. Our results suggest that the investigated sirtuins may influence the HSC migration and hematopoietic landscape during mobilization. SIRT5, SIRT6, and SIRT7 may be associated with the efficacy of HSC mobilization.

Combined Effects of Tanshinone IIA and an Autophagy Inhibitor on the Apoptosis of Leukemia Cells via p53, Apoptosis-Related Proteins and Oxidative Stress Pathways

Background:

Acute myeloid leukemia (AML) is a kind of hematopoietic malignancy with limited response and acquired resistance to therapy. Inducing apoptosis and inhibiting autophagy in tumor cells is a combinational strategy for the development of anticancer therapeutics. Tanshinone IIA (TAIIA) is one of the major ingredients in Salvia miltiorrhiza, which is the most prescribed herb for the treatment of AML in Taiwan. Therefore, this study aimed to delineate the anticancer effects of TAIIA and its effect when combined with an autophagy inhibitor to treat AML.

Methods:

The anticancer effects of a combination of TAIIA and the autophagy inhibitor 3-methladenine (3MA) on the human monocytic leukemia cell line THP-1 were explored. The apoptosis and cell cycle of the leukemia cells were examined by Annexin V and propidium iodide staining and analyzed by flow cytometry. The oxidative stress level was determined by a malondialdehyde (MDA) colorimetric assay, nitric oxide colorimetric assay and glutathione peroxidase (GPx) colorimetric assay. The expression of apoptosis-related proteins was determined by western blotting.

Results:

TAIIA treatment significantly induced apoptosis via increased p53, Bax/Bcl, PARP, and caspase-3 signals and oxidative stress by enhancing MDA and nitrate/nitrite production and reducing GPx activity in THP-1 cells in a dose-dependent and time-dependent manner. The combination of the autophagy inhibitor 3MA enhanced TAIIA-induced apoptosis via the p53, Bax/Bcl, PARP, caspase-3, and oxidative stress pathways in THP-1 cells.

Conclusion:

The results suggest that TAIIA and autophagy inhibitors have combined effects on the apoptosis of leukemia cells, thus representing a novel and effective combination with the potential for application as a clinical therapy for AML.

Mild hyperthermia induced by gold nanorods acts as a dual-edge blade in the fate of SH-SY5Y cells via autophagy

Unraveling unwanted side effects of nanotechnology-based therapies like photothermal therapy (PTT) is vital in translational nanomedicine. Herein, we monitored the relationship between autophagic response at the transcriptional level by using a PCR array and tumor formation ability by colony formation assay in the human neuroblastoma cell line, SH-SY5Y, 48 h after being exposed to two different mild hyperthermia (43 and 48 °C) induced by PTT. In this regard, the promotion of apoptosis and autophagy were evaluated using immunofluorescence imaging and flow cytometry analyses. Protein levels of Ki-67, P62, and LC3 were measured using ELISA. Our results showed that of 86 genes associated with autophagy, the expression of 54 genes was changed in response to PTT. Also, we showed that chaperone-mediated autophagy (CMA) and macroautophagy are stimulated in PTT. Importantly, the results of this study also showed significant changes in genes related to the crosstalk between autophagy, dormancy, and metastatic activity of treated cells. Our findings illustrated that PTT enhances the aggressiveness of cancer cells at 43 °C, in contrast to 48 °C by the regulation of autophagy-dependent manner.

TCP1 increases drug resistance in acute myeloid leukemia by suppressing autophagy via activating AKT/mTOR signaling

T-complex protein 1 (TCP1) is one of the subunits of chaperonin-containing T complex (CCT), which is involved in protein folding, cell proliferation, apoptosis, cell cycle regulation, and drug resistance. Investigations have demonstrated that TCP1 is a factor being responsible for drug resistance in breast and ovarian cancer. However, the TCP1 role in acute myeloid leukemia (AML) remains elusive. In the present study, we discovered that the TCP1 expression was elevated in AML patients and high TCP1 expression was associated with low complete response rate along with poor overall survival. TCP1 showed higher expression in the adriamycin-resistant leukemia cell line HL60/A and K562/A, comparing to their respective parent cells HL60 and K562 cells. TCP1 inhibition suppressed drug resistance in HL60/A and K562/A cells, whereas TCP1 overexpression in HL60 cells incremented drug resistance, both in vitro and in vivo. Mechanistic investigations revealed that TCP1 inhibited autophagy and adriamycin-induced cell apoptosis, and TCP1-mediated autophagy inhibition conferred resistance to adriamycin-induced cell apoptosis. Furthermore, TCP1 interacted with AKT and mTOR to activate AKT/mTOR signaling, which negatively regulates apoptosis and autophagy. Pharmacological inhibition of AKT/mTOR signal particularly activated autophagy and resensitized TCP1-overexpressing HL60 cells to adriamycin. These findings identify a novel role of TCP1 regarding drug resistance in AML, which advise a new strategy for overcoming drug resistance in AML through targeting TCP1/AKT/mTOR signaling pathway.

Development and validation of a novel survival model for acute myeloid leukemia based on autophagy-related genes

Background

Acute myeloid leukemia (AML) is one of the most common blood cancers, and is characterized by impaired hematopoietic function and bone marrow (BM) failure. Under normal circumstances, autophagy may suppress tumorigenesis, however under the stressful conditions of late stage tumor growth autophagy actually protects tumor cells, so inhibiting autophagy in these cases also inhibits tumor growth and promotes tumor cell death.

Methods

AML gene expression profile data and corresponding clinical data were obtained from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, from which prognostic-related genes were screened to construct a risk score model through LASSO and univariate and multivariate Cox analyses. Then the model was verified in the TCGA cohort and GEO cohorts. In addition, we also analyzed the relationship between autophagy genes and immune infiltrating cells and therapeutic drugs.

Results

We built a model containing 10 autophagy-related genes to predict the survival of AML patients by dividing them into high- or low-risk subgroups. The high-risk subgroup was prone to a poorer prognosis in both the training TCGA-LAML cohort and the validation GSE37642 cohort. Univariate and multivariate Cox analysis revealed that the risk score of the autophagy model can be used as an independent prognostic factor. The high-risk subgroup had not only higher fractions of CD4 naïve T cell, NK cell activated, and resting mast cells but also higher expression of immune checkpoint genes CTLA4 and CD274. Last, we screened drug sensitivity between high- and low-risk subgroups.

Conclusion

The risk score model based on 10 autophagy-related genes can serve as an effective prognostic predictor for AML patients and may guide for patient stratification for immunotherapies and drugs.

LncRNA H19 Aggravates Intervertebral Disc Degeneration by Promoting the Autophagy and Apoptosis of Nucleus Pulposus Cells Through the miR-139/CXCR4/NF-κB Axis

The etiology of lumbocrural pain is closely related to intervertebral disc degeneration (IDD). Long noncoding RNAs (lncRNAs) serve crucial roles in IDD progression. This study investigated the effect of lncRNA H19 on autophagy and apoptosis of nucleus pulposus cells (NPCs) in IDD. The rat model of IDD was established. Normal NPCs and degenerative NPCs (DNPCs) were cultured in vitro. H19 expression in IDD rat was detected. DNPCs were treated with si-H19 to evaluate autophagy and apoptosis of DNPCs. The binding relationships between H19 and miR-139-3p, and miR-139-3p and CXCR4 were verified. DNPCs were co-transfected si-H19 and miR-139-3p inhibitor. The phosphorylation of NF-κB pathway-related p65 in DNPCs was detected. LncRNA H19 was upregulated in IDD rats. Downregulation of H19 inhibited autophagy and apoptosis of DNPCs. LncRNA H19 sponged miR-139-3p to inhibit CXCR4 expression. si-H19 and miR-139-3p inhibitor co-treatment induced autophagy and apoptosis, and enhanced CXCR4 expression. si-H19 decreased p-p65 phosphorylation, while si-H19 and miR-139-3p inhibitor co-treatment partially elevated p-p65 phosphorylation. In conclusion, lncRNA H19 facilitated the autophagy and apoptosis of DNPCs by the miR-139-3p/CXCR4/NF-κB axis, thereby aggravating IDD. This study may offer new insights for the management of IDD.

Retinoblastoma tumor suppressor gene 1 enhances 5-Fluorouracil chemosensitivity through SDF-1/CXCR4 axis by regulating autophagy in gastric cancer

Due to lack of effective biomarkers for early diagnosis, most patients are diagnosed with advanced gastric cancer and have lower survival rates. 5-Fluorouracil (5-FU) is one of commonly used drugs for chemotherapy of gastric cancer, but drug resistance limits the wide application of agents. Retinoblastoma tumor suppressor gene 1 (RB1) is a key regulator in the progression of various human cancers, including gastric cancer. However, the effects of RB1 on chemosensitivity and the underlying mechanisms in gastric cancer (GC) are not clear. In this study, expressions of RB1 in GC cell lines were evaluated by RT-qPCR and western blot assay. CCK-8 was applied to examine the effect of 5-FU on cell viability. Meanwhile, IC50 values were calculated. The drug-resistance protein MDR1 and autophagy-related proteins were detected by western blot assay. Flow cytometry was used to detect cell cycle. The results showed that RB1 expressions were downregulated in GC cell lines and had significant differences between 5-FU resistance cell lines (SNU-620/5-FU and NUGC-3/5-FU) and non-resistance cell lines (SNU-620 and NUGC-3). Overexpression of RB1 enhanced 5-FU sensitivity of GC cells and caused cell cycle arrest in the S phase. Meanwhile, autophagy-related proteins were downregulated. Mechanistically, SDF-1/CXCR4 participated in the regulation of RB1 on cell autophagy. Autophagy activator, SDF-1 treatment and CXCR4 activation reversed the promoted effects of RB1 on 5-FU sensitivity in GC cells. In conclusion, our data revealed that RB1 was downregulated in GC cell lines. RB1 overexpression enhanced 5-FU chemosensitivity in GC cells by regulating cell autophagy via SDF-1/CXCR4 pathway. RB1 might serve as a promising therapeutic target of GC.

CXCR4 blockade sensitizes osteosarcoma to doxorubicin by inducing autophagic cell death via PI3K‑Akt‑mTOR pathway inhibition

Doxorubicin is one of the most frequently used chemotherapy drugs in the treatment of osteosarcoma (OS), but the emergence of chemoresistance often leads to treatment failure. C-X-C motif chemokine receptor 4 (CXCR4) has been demonstrated to regulate OS progression and metastasis. However, whether CXCR4 is also involved in OS chemoresistance and its molecular mechanisms has yet to be fully elucidated. In the present study, CXCR4-mediated autophagy for OS chemotherapy was investigated by western blot analysis, transmission electron microscopy and confocal microscopy. CXCR4 silencing enhanced doxorubicin-induced apoptosis by reducing P-glycoprotein in CXCR4⁺ LM8 cells, while CXCR4 overexpression promoted OS doxorubicin resistance in CXCR4⁻Dunn cells. Furthermore, CXCR4 silencing with or without doxorubicin increased the expression of beclin 1 and light chain 3B, and the number of autophagosomes and autolysosomes, as well as induced autophagic flux activation by suppressing the PI3K/AKT/mTOR signaling pathway. In addition, pretreatment with the autophagy inhibitor bafilomycin A1 attenuated CXCR4 abrogation-induced cell death. Finally, the CXCR4 antagonist AMD3100 synergistically reinforced the antitumor effect of doxorubicin in an orthotopic OS mouse model. Taken together, the present study revealed that CXCR4 inhibition sensitizes OS to doxorubicin by inducing autophagic cell death. Therefore, targeting the CXCR4/autophagy axis may be a promising therapeutic strategy to overcome OS chemotherapy resistance.

Identification of autophagy-related gene and lncRNA signatures in the prognosis of HNSCC

OBJECTIVE

The aim of this study was to identify prognostic autophagy-related genes and lncRNAs to predict clinical outcomes in head and neck squamous cell carcinoma (HNSCC).

SUBJECTS AND METHODS

Differentially expressed autophagy-related genes and autophagy-related lncRNAs were identified by comparing pare-carcinoma and carcinoma samples of HNSCC. And then, we constructed an ARG and an AR-lncRNA signature risk score. Receiver operating characteristic (ROC) curve analyses were performed to assess the prognostic prediction capacity. Gene Set Enrichment Analysis (GSEA) and Gene Ontology (GO) functional annotation were used to analysis the functions of ARGs and AR-lncRNAs.

RESULTS

Six ARGs and thirteen AR-lncRNAs were identified in the ARG and AR-lncRNA signatures, and overall survival (OS) in the high-risk group was significantly shorter than the low-risk group. ROC analysis showed the ARG and AR-lncRNA signatures have excellent ability of predicting the total OS of patients with HNSCC. What's more, GSEA and GO functional annotation proved that autophagy-related pathways are mainly enriched in the high-risk group.

CONCLUSIONS

These findings indicated that our ARG signature and AR-lncRNA signature could be considered to predict the prognosis of patients with HNSCC and provide a deep understanding of the biological mechanisms of autophagy in HNSCC.

Association of SDF-1 Gene Polymorphism with Increased Risk of Acute Myeloid Leukemia Patients

Background:

Acute myeloid leukemia (AML) is a heterogenous group of disorders that emerge from the malignant transformation of hematopoietic stem cells. Chemokine stromal cell-derived factor 1(SDF-1) and its receptor CXC receptor 4 (CXCR4) has an essential role in dissemination of blast cells. Study aimed to detect CXCR4 expression and the SDF-1 (rs1801157) gene polymorphisms and correlate them with prognosis and outcome in AML patients.

Subjects and Methods:

The study was conducted on 60 de-novo AML patients, and 60 healthy controls. SDF-1 (rs1801157) gene polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and CXCR4 expression was done using flow cytometry analysis.

Results:

SDF-1 dominant model (AG+AA) had higher risk AML (p 0.002). CXCR4 positive cases were associated significantly with toxic manifestations (p 0.019), lower CR rates (p 0.004), and unfavorable cytogenetics (p 0.027). Multivariate analysis showed that combined CXCR4positive with dominant SDF-1 considered as independent prognostic factor for shorter overall survival (OS) in AML patients (p 0.031).

Conclusion:

SDF-1 dominant model had a higher risk to develop AML, and CXCR4 positive expression predicts poor prognosis in AML patients and it could represent a targeted therapy in AML. In addition, CXCR4 could be easily integrated into the initial routine diagnostic work up of AML.

Alzheimer's Disease Pathogenesis: Role of Autophagy and Mitophagy Focusing in Microglia

Alzheimer's disease (AD) is a debilitating neurological disorder, and currently, there is no cure for it. Several pathologic alterations have been described in the brain of AD patients, but the ultimate causative mechanisms of AD are still elusive. The classic hallmarks of AD, including amyloid plaques (Aβ) and tau tangles (tau), are the most studied features of AD. Unfortunately, all the efforts targeting these pathologies have failed to show the desired efficacy in AD patients so far. Neuroinflammation and impaired autophagy are two other main known pathologies in AD. It has been reported that these pathologies exist in AD brain long before the emergence of any clinical manifestation of AD. Microglia are the main inflammatory cells in the brain and are considered by many researchers as the next hope for finding a viable therapeutic target in AD. Interestingly, it appears that the autophagy and mitophagy are also changed in these cells in AD. Inside the cells, autophagy and inflammation interact in a bidirectional manner. In the current review, we briefly discussed an overview on autophagy and mitophagy in AD and then provided a comprehensive discussion on the role of these pathways in microglia and their involvement in AD pathogenesis.

Downregulation of long non-protein coding RNA MVIH impairs glioblastoma cell proliferation and invasion through an miR-302a-dependent mechanism

Glioblastoma (GB) is the most frequent and malignant type of brain tumor, for which no effective therapy exists. The high proliferative and invasive nature of GB, as well as its acquired resistance to chemotherapy, makes this type of cancer extremely lethal shortly after diagnosis. Long non-protein coding RNAs (lncRNA) are a class of regulatory RNAs whose levels can be dysregulated in the context of diseases, unbalancing several physiological processes. The lncRNA associated with microvascular invasion in hepatocellular carcinoma (lncRNA-MVIH), overexpressed in several cancers, was described to co-precipitate with phosphoglycerate kinase 1 (PGK1), preventing secretion of this enzyme to the extracellular environment and promoting cell migration and invasion. We hypothesized that, by silencing the expression of lncRNA-MVIH, the secretion of PGK1 would increase, reducing GB cell migration and invasion capabilities. We observed that lncRNA-MVIH silencing in human GB cells significantly decreased glycolysis, cell growth, migration, and invasion and sensitized GB cells to cediranib. However, no increase in extracellular PGK1 was observed as a consequence of lncRNA-MVIH silencing, and therefore, we investigated the possibility of a mechanism of miRNA sponge of lncRNA-MVIH being in place. We found that the levels of miR-302a loaded onto RISC increased in GB cells after lncRNA-MVIH silencing, with the consequent downregulation of several miR-302a molecular targets. Our findings suggest a new mechanism of action of lncRNA-MVIH as a sponge of miR-302a. We suggest that lncRNA-MVIH knockdown may be a promising strategy to address GB invasiveness and chemoresistance, holding potential towards its future application in a clinical context.

Challenges and Therapeutic Opportunities of Autophagy in Cancer Therapy

Simple Summary

Autophagy is a physiological process characterized by the degradation of the cell components through lysosomes due to stimuli/stress. In this study, we review the challenges and therapeutic opportunities that autophagy presents in the treatment of cancer. We discussed the results of several studies that evaluated autophagy as a therapeutic strategy in cancer, both through the modulation of therapeutic resistance and the death of cancer cells. Moreover, we discussed the role of autophagy in the biology of cancer stem cells and the inhibition of this process as a strategy to overcome resistance and progression of cancer stem cells.

Abstract

Autophagy is a physiological cellular process that is crucial for development and can occurs in response to nutrient deprivation or metabolic disorders. Interestingly, autophagy plays a dual role in cancer cells—while in some situations, it has a cytoprotective effect that causes chemotherapy resistance, in others, it has a cytotoxic effect in which some compounds induce autophagy-mediated cell death. In this review, we summarize strategies aimed at autophagy for the treatment of cancer, including studies of drugs that can modulate autophagy-mediated resistance, and/or drugs that cause autophagy-mediated cancer cell death. In addition, the role of autophagy in the biology of cancer stem cells has also been discussed.

The role of autophagy in targeted therapy for acute myeloid leukemia

Although molecular targeted therapies have recently displayed therapeutic effects in acute myeloid leukemia (AML), limited response and acquired resistance remain common problems. Numerous studies have associated autophagy, an essential degradation process involved in the cellular response to stress, with the development and therapeutic response of cancers including AML. Thus, we review studies on the role of autophagy in AML development and summarize the linkage between autophagy and several recurrent genetic abnormalities in AML, highlighting the potential of capitalizing on autophagy modulation in targeted therapy for AML.Abbreviations: AML: acute myeloid leukemia; AMPK: AMP-activated protein kinase; APL: acute promyelocytic leukemia; ATG: autophagy related; ATM: ATM serine/threonine kinase; ATO: arsenic trioxide; ATRA: all trans retinoic acid; BCL2: BCL2 apoptosis regulator; BECN1: beclin 1; BET proteins, bromodomain and extra-terminal domain family; CMA: chaperone-mediated autophagy; CQ: chloroquine; DNMT, DNA methyltransferase; DOT1L: DOT1 like histone lysine methyltransferase; FLT3: fms related receptor tyrosine kinase 3; FIS1: fission, mitochondrial 1; HCQ: hydroxychloroquine; HSC: hematopoietic stem cell; IDH: isocitrate dehydrogenase; ITD: internal tandem duplication; KMT2A/MLL: lysine methyltransferase 2A; LSC: leukemia stem cell; MDS: myelodysplastic syndromes; MTORC1: mechanistic target of rapamycin kinase complex 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; NPM1: nucleophosmin 1; PIK3C3/VPS34: phosphatidylinositol 3-kinase catalytic subunit type 3; PML: PML nuclear body scaffold; ROS: reactive oxygen species; RB1CC1/FIP200: RB1 inducible coiled-coil 1; SAHA: vorinostat; SQSTM1: sequestosome 1; TET2: tet methylcytosine dioxygenase 2; TKD: tyrosine kinase domain; TKI: tyrosine kinase inhibitor; TP53/p53: tumor protein p53; ULK1: unc-51 like autophagy activating kinase 1; VPA: valproic acid; WDFY3/ALFY: WD repeat and FYVE domain containing 3.

Casein kinase 1α inhibits p53 downstream of MDM2‑mediated autophagy and apoptosis in acute myeloid leukemia

Enhancement of autophagy serves as a promising therapeutic strategy for cancer, including acute myeloid leukemia (AML). Casein kinase 1α (CK1α), encoded by CSNK1A1, regulates Wnt/β-catenin, p53 and other key signaling pathways, and is critically involved in tumor progression. However, the relationship and mechanism of CK1α with autophagy in AML still remain unclear. In the present study, it was found that AML patients had higher expression of CSNK1A1 mRNA than healthy donors. Furthermore, we analyzed 163 cases of AML patients in the LAML database of TCGA and found that AML patients with high CSNK1A1 had shorter overall survival than those with low or medium CSNK1A1 expression. Furthermore, we demonstrated that CK1α was a negative regulator of autophagy and apoptosis. Pharmacologic inhibition of CK1α using D4476 or CK1α knockdown via lentivirus-mediated shRNA suppressed proliferation and the clone formation by enhancing autophagic flux and apoptosis in AML cell lines as well as in patient blast cells. Intriguingly, D4476-induced cell death was aggravated in combination with an autophagy inhibitor, Spautin-1, suggesting that autophagy may be a pro-survival signaling. CK1α interacted with murine double minute 2 (MDM2) and p53, and CK1α inhibitor D4476 significantly upregulated p53 and phosphorylated 5′ AMP-activated protein kinase (AMPK), and substantially inhibited the phosphorylation of mammalian target of rapamycin (mTOR). Our findings indicate that CK1α promotes AML by suppressing p53 downstream of MDM2-mediated autophagy and apoptosis, suggesting that targeting CK1α provides a therapeutic opportunity to treat AML.

Synthetic CXCR4 Antagonistic Peptide Assembling with Nanoscaled Micelles Combat Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is the most common adult acute leukemia with very low survival rate due to drug resistance and high relapse rate. The C-X-C chemokine receptor 4 (CXCR4) is highly expressed by AML cells, actively mediating chemoresistance and reoccurrence. Herein, a chemically synthesized CXCR4 antagonistic peptide E5 is fabricated to micelle formulation (M-E5) and applied to refractory AML mice, and its therapeutic effects and pharmacokinetics are investigated. Results show that M-E5 can effectively block the surface CXCR4 in leukemic cells separated from bone marrow (BM) and spleen, and inhibit the C-X-C chemokine ligand 12-mediated migration. Subcutaneous administration of M-E5 significantly inhibits the engraftment of leukemic cells in spleen and BM, and mobilizes residue leukemic cells into peripheral blood, reducing organs' burden and significantly prolonging the survival of AML mice. M-E5 can also increase the efficacy of combining regime of homoharringtonine and doxorubicin. Ribonucleic acid sequencing demonstrates that the therapeutic effect is contributed by inhibiting proliferation and enhancing apoptosis and differentiation, all related to the CXCR4 signaling blockade. M-E5 reaches the concentration peak at 2 h after administration with a half-life of 14.5 h in blood. In conclusion, M-E5 is a novel promising therapeutic candidate for refractory AML treatment.

Genetic biomarkers of drug resistance: A compass of prognosis and targeted therapy in acute myeloid leukemia

Acute myeloid leukemia (AML) is a highly aggressive hematological malignancy with complex heterogenous genetic and biological nature. Thus, prognostic prediction and targeted therapies might contribute to better chemotherapeutic response. However, the emergence of multidrug resistance (MDR) markedly impedes chemotherapeutic efficacy and dictates poor prognosis. Therefore, prior evaluation of chemoresistance is of great importance in therapeutic decision making and prognosis. In recent years, preclinical studies on chemoresistance have unveiled a compendium of underlying molecular basis, which facilitated the development of targetable small molecules. Furthermore, routing genomic sequencing has identified various genomic aberrations driving cellular response during the course of therapeutic treatment through adaptive mechanisms of drug resistance, some of which serve as prognostic biomarkers in risk stratification. However, the underlying mechanisms of MDR have challenged the certainty of the prognostic significance of some mutations. This review aims to provide a comprehensive understanding of the role of MDR in therapeutic decision making and prognostic prediction in AML. We present an updated genetic landscape of the predominant mechanisms of drug resistance with novel targeted therapies and potential prognostic biomarkers from preclinical and clinical chemoresistance studies in AML. We particularly highlight the unfolded protein response (UPR) that has emerged as a critical regulatory pathway in chemoresistance of AML with promising therapeutic horizon. Futhermore, we outline the most prevalent mutations associated with mechanisms of chemoresistance and delineate the future directions to improve the current prognostic tools. The molecular analysis of chemoresistance integrated with genetic profiling will facilitate decision making towards personalized prognostic prediction and enhanced therapeutic efficacy.

Over-expression of EGFR regulated by RARA contributes to 5-FU resistance in colon cancer

A promising new strategy for cancer therapy is to target the autophagic pathway. However, comprehensive characterization of autophagy genes and their clinical relevance in cancer is still lacking. Here, we systematically characterized alterations of autophagy genes in multiple cancer lines by analyzing data from The Cancer Genome Atlas and CellMiner database. Interactions between autophagy genes and clinically actionable genes (CAGs) were identified by analyzing co-expression, protein-protein interactions (PPIs) and transcription factor (TF) data. A key subnetwork was identified that included 18 autophagy genes and 22 CAGs linked by 28 PPI pairs and 1 TF-target pair, which was EGFR targeted by RARA. Alterations in the expression of autophagy genes were associated with patient survival in multiple cancer types. RARA and EGFR were associated with worse survival in colorectal cancer patients. The regulatory role of EGFR in 5-FU resistance was validated in colon cancer cells in vivo and in vitro. EGFR contributed to 5-FU resistance in colon cancer cells through autophagy induction, and EGFR overexpression in 5-FU resistant colon cancer was regulated by RARA. The present study provides a comprehensive analysis of autophagy in different cancer cell lines and highlights the potential clinical utility of targeting autophagy genes.

Targeted inhibition of ULK1 enhances daunorubicin sensitivity in acute myeloid leukemia

PURPOSE

In acute myeloid leukemia (AML), complete remission can be achieved in parts of patients using cytarabine/anthracycline combination-based chemotherapy, however, drug resistance-related recurrence is still a common cause of treatment failure, leading to high mortality among patients. In our research, we revealed the molecular mechanisms that were sufficient to improve sensitivity of AML cells to the anthracycline daunorubicin (DNR).

METHODS

We evaluated the effects of autophagy and apoptosis induced by DNR using two AML cell lines HL60 and U937.Western blot was preformed to analyze the apoptotic pathway protein expression and flow cytometric analysis was used to detect the level of apoptosis in AML cells. The levels of autophagy-related proteins were detected by western blotting and autophagic vesicles were observed by electron microscopy.

RESULTS

DNR effectively induced autophagy in two AML cell lines HL60 and U937 confirming by upregulation of LC3-II lipidation, formation of autophagosomes. Inhibition of autophagy by pharmacologic inhibitor HCQ promoted apoptosis induced by DNR, suggesting that autophagy played a vital role in pro-survival in AML. Furthermore, ULK1 inhibition by a highly selective kinase inhibitor SBI-0206965 and shRNA enhanced cytotoxicity of DNR against AML cells. Independent of mTOR -ULK1 signaling pathway, activation of autophagy of DNR was proved to be mediated by AMPK (pThr172)/ULK1 pathway.

CONCLUSIONS

These results revealed that pro-survival autophagy induced by ULK1 activation was one of the potential mechanisms of AML resistance to DNR. Targeting ULK1 selectively could be a promising therapeutic strategy to enhance sensitivity of DNR for AML therapy.

Clinicopathologic significance of CXCR4 expressions in patients with esophageal squamous cell carcinoma

AIMS

This study was designed to investigate the biological function of CXCR4 in esophageal squamous cell carcinoma and to explore the underlying mechanism to provide potential targets for esophageal squamous cell carcinoma.

METHODS

A total of 101 patients with esophageal squamous cell carcinoma were included, and the relationship between CXCR4 and clinicopathological factors was analyzed. Laser scanning confocal microscopy was used to observe numbers of autophagosomes in TE-1 cell line and the ability of proliferation and invasion were evaluated meanwhile.

RESULTS

CXCR4 is overexpressed in ESCC specimens and is associated with poor differentiation and lymphocyte metastasis. In the survival analysis, CXCR4 predicted a poor overall survival prognosis. The number of autophagosomes in the siR-CXCR4 group was decreased compared with negative group (P < 0.05), while was increased in the pcDNA3.1-CXCR4 group (P < 0.05).Western blot result show upregulation of LC3II, the ratio of LC3II/LC3I and Beclin1 in pcDNA3.1-CXCR4 group and decreased expression of LC3II, the ratio of LC3II/LC3I and Beclin1 in siR-CXCR4 group. Transwell assay show CXCR4 overexpression promote the invasion of TE-1 cells and was attenuated by autophagy inhibitor 3-Methyladenine.On the contrary, invasion cell numbers decreased in siR-CXCR4 group and was rescued by autophagy inducer Rapamycin.

CONCLUSION

CXCR4 is an indicator of poor prognosis for ESCC. CXCR4 promote autophagy and regulate cell invasion through autophagy in ESCC. Our study provides new insights for the treatment of esophageal squamous cell carcinoma and CXCR4 may serve as a therapeutic target for ESCC.

Ghrelin induces autophagy and CXCR4 expression via the SIRT1/AMPK axis in lymphoblastic leukemia cell lines

T cell acute lymphoblastic leukemia (T-ALL) is one of the most frequent malignancies in children, and the CXCR4 receptor plays an important role in the metastasis of this malignancy. Ghrelin is a hormone with various functions including stimulation of the release of growth hormone and autophagy in cancer cells. Moreover, SIRT1 and AMPK (AMP-activated protein kinase) stimulate expression of proteins involved in autophagy. On the other hand, autophagic cell death can be an alternative target for cancer therapy, in the absence of apoptosis. The relationship between ghrelin and the SIRT1/AMPK axis and the resulting effects on autophagy, apoptosis, proliferation, and expression of CXCR4 and the ghrelin receptor (GHS-R1a), in Jurkat and Molt-4 human lymphoblastic cell lines was not previously clear. Here we demonstrate that SIRT1 expression is upregulated during the induction of autophagy by ghrelin, an effect that is inhibited by inactivation of SIRT1/AMPK axis. In addition, ghrelin can affect CXCR4 and GHS-R1a expression. In conclusion, this work reveals that ghrelin induces autophagy, invasion, and downregulation of ghrelin receptor expression via the SIRT1/AMPK axis in lymphoblastic cell lines. However, in these cell lines ghrelin-induced autophagy does not lead to cell death due to weak induction of apoptosis.

CXCR4 signaling at the ovine fetal-maternal interface regulates vascularization, CD34+ cell presence, and autophagy in the endometrium†

Placenta development is characterized by extensive angiogenesis and vascularization but if these processes are compromised placental dysfunction occurs, which is the underlying cause of pregnancy complications such as preeclampsia and intrauterine growth restriction. Dysregulation of placental angiogenesis has emerged as one of the main pathophysiological features in the development of placental insufficiency and its clinical consequences. The signaling axis initiated by chemokine ligand 12 (CXCL12) and its receptor CXCR4 stimulates angiogenesis in other tissues, and may be central to placental vascularization. We hypothesized that CXCL12-CXCR4 signaling governs the pro-angiogenic placental microenvironment by coordinating production of central angiogenic factors and receptors and regulates endometrial cell survival essential for placental function and subsequent fetal longevity. The CXCR4 antagonist, AMD3100, was used to elucidate the role of CXCL12-CXCR4 signaling regarding uteroplacental vascular remodeling at the fetal-maternal interface. On day 12 postbreeding, osmotic pumps were surgically installed and delivered either AMD3100 or PBS into the uterine lumen ipsilateral to the corpus luteum. On day 20, endometrial tissues were collected, snap-frozen in liquid nitrogen, and uterine horn cross sections preserved for immunofluorescent analysis. In endometrium from ewes receiving AMD3100 infusion, the abundance of select angiogenic factors was diminished, while presence of CD34+ cells increased compared to control ewes. Ewes receiving AMD3100 infusion also exhibited less activation of Akt/mTOR signaling, and elevated LC3B-II, a marker of cellular autophagy in endometrium. This study suggests that CXCL12-CXCR4 signaling governs placental homeostasis by serving as a critical upstream mediator of vascularization and cell viability, thereby ensuring appropriate placental development.

Notch/CXCR4 Partnership in Acute Lymphoblastic Leukemia Progression

Acute lymphoblastic leukemia (ALL) is the most common cancer among children. Recent advances in chemotherapy have made ALL a curable hematological malignancy. In children, there is 25% chance of disease relapse, typically in the central nervous system. While in adults, there is a higher chance of relapse. ALL may affect B-cell or T-cell lineages. Different genetic alterations characterize the two ALL forms. Deregulated Notch, either Notch1 or Notch3, and CXCR4 receptor signaling are involved in ALL disease development and progression. By analyzing their relevant roles in the pathogenesis of the two ALL forms, new molecular mechanisms able to modulate cancer cell invasion may be visualized. Notably, the partnership between Notch and CXCR4 may have considerable implications in understanding the complexity of T- and B-ALL. These two receptor pathways intersect other critical signals in the proliferative, differentiation, and metabolic programs of lymphocyte transformation. Also, the identification of the crosstalks in leukemia-stroma interaction within the tumor microenvironment may unveil new targetable mechanisms in disease relapse. Further studies are required to identify new challenges and opportunities to develop more selective and safer therapeutic strategies in ALL progression, possibly contributing to improve conventional hematological cancer therapy.

Relationship between CXC chemokine receptor 4 expression and prognostic significance in acute myeloid leukemia

CXC chemokine receptor 4 (CXCR4) expression on acute myeloid leukemia (AML) cells correlated with stromal cell derived factor-1α (SDF-1α) and retained hematopoietic progenitors and leukemia cells within the bone marrow microenvironment. Here, we examined CXCR4 expression in 134 de novo AML and 21 controls by flow cytometry, evaluated the relationship between CXCR4 expression and clinical characteristics, and elucidated the prognostic significance of CXCR4 expression in AML prospectively. We found that the CXCR4 expression was significantly higher in AML patients than controls (P = .000). One hundred thirty four cases of de novo AML patients were divided into 2 groups according to the median of CXCR4 relative fluorescence intensity (RFI). CXCR4 high group (RFI >4.23) had markedly shorter overall survival (OS) and disease-free survival (DFS) than CXCR4 low group (RFI ≤4.23) in 106 AML patients who received chemotherapy (P = .002; .026, respectively). Furthermore, in the 87 non-M3 patients who received induction therapy, there was a significant decrease for OS but not for DFS in the CXCR4 high group (P = .047 and .178, respectively). Moreover, high levels of CXCR4 expression independently increased the risk of relapse in both all AML and non-M3 patients who achieved complete remission (CR) after chemotherapy (odds ratio = 1.090, P = .010; odds ratio = 1.068, P = .048, respectively). Collectively, our data suggest that CXCR4 overexpression was an independent prognostic factor for disease relapse and poorer OS in both all AML and non-M3 patients. CXCR4 expression levels can be determined at disease presentation by the flow rapidly and easily. As such, CXCR4 could be used as a potential therapeutic target in AML patients with poor prognosis.

BM-MSCs-derived ECM modifies multiple myeloma phenotype and drug response in a source-dependent manner

Multiple myeloma (MM) malignant plasma cells accumulate in the bone marrow (BM) where their interaction with the microenvironment promotes disease progression and drug resistance. Previously, we have shown that MM cells cocultured with BM-mesenchymal stem cells (MSCs) comodulated cells' phenotype in a MAPKs/translation initiation (TI)-dependent manner. Dissection of the coculture model showed that BM-MSCs secretomes and microvesicles (MVs) participate in this crosstalk. Here, we addressed the role of the BM-MSCs extracellular matrix (ECM). MM cell lines cultured on decellularized ECM of normal donors' (ND) or MM patients' BM-MSCs were assayed for phenotype (viability, cell count, death, proliferation, migration, and invasion), microRNAs (MIR125a-3p, MIR199a-3p) and targets, MAPKs, TI epithelial-to-mesenchymal transition (EMT), CXCR4, and autophagy. Drug (doxorubicin, velcade) response of MM cells cultured on ND/MM-MSCs' ECM with/without adhered MVs was also evaluated. ECM evoked opposite responses according to its origin: MM cells cultured on ND-MSCs' ECM demonstrated a rapid and continued decrease in MAPK/TI activation (↓10%-25%, P < 0.05) (15-24 hours) followed by diminished viability, cell count, proliferation, migration, and invasion (16-72 hours) (↓10%-50%, P < 0.05). In contrast, MM cells cultured on MM-MSCs' ECM displayed activated MAPK/TI, proliferation, EMT, and CXCR4 (↑15%-250%, P < 0.05). Corresponding changes in microRNAs relevant to the MM cells' altered phenotype were also determined. The hierarchy and interdependence of MAPKs/TI/autophagy/phenotype cascade were demonstrated. Finally, we showed that the ECM cooperates with MVs to modulate MM cells drug response. These data demonstrate the contribution of BM-MSCs' ECM to MM niche design and underscore the clinical potential of identifying targetable signals.

The significance of chemokines in diffuse large B-cell lymphoma: a systematic review and future insights

Despite the progress made in molecular and clinical research, patients with diffuse large B-cell lymphoma (DLBCL) still have a bad prognosis. Recently, chemokines/chemokine receptors have become the subject of interest in relation to DLBCL. Studies have demonstrated the important role of chemokines/chemokine receptors in the communication between DLBCL cells and tumor microenvironment. Studies have also reported the ability of chemokines/chemokine receptors in promoting the proliferation and invasion of DLBCL cells. Here, we summarize the data on mechanisms of DLBCL supporting the involvement of chemokine/chemokine receptor changes. We focus on the available evidence regarding chemokines/chemokine receptors as biomarkers and therapeutic targets for DLBCL.