JNK initiates Beclin-1 dependent autophagic cell death against Akt activation

Combination treatment with Phloretin enhances the anti-tumor efficacy of radiotherapy in lung cancer models

INTRODUCTION

Phloretin (Ph), an apple polyphenol, has been shown to possess anti-tumor effects. This study aimed to investigate the anti-tumor effects of the combination of Ph and radiotherapy on lung cancer.

METHODS

The proliferative rate of Lewis lung carcinoma (LLC) cells treated with Ph was evaluated using the MTT assay. The radiosensitization effect of Ph was assessed using the clone formation assay. Additionally, the anti-tumor and radiosensitization effects of Ph were explored in LLC xenografts in mice.

RESULTS

Ph inhibited the proliferation of LLC cells in a time- and dose-dependent manner (p < 0.05). Moreover, the combination of Ph with radiotherapy significantly inhibited LLC cell colony formation (p < 0.05). In vivo studies demonstrated that the combination of Ph with radiotherapy significantly inhibited tumor growth, achieving a tumor inhibition rate of 74.44% compared to the control group (p < 0.01). This combination also prolonged the median survival times of mice by 31 days compared to the control group (p < 0.01), reduced tumor glucose uptake, promoted tumor cell apoptosis, and suppressed tumor cell proliferation.

CONCLUSION

This study suggests that the combination of Ph with radiotherapy exhibits promising activity against lung cancer, potentially through mechanisms including inhibition of glucose transport and promotion of apoptosis. These findings may provide a new therapeutic strategy for improving lung cancer treatment.

Autophagy fine-tuning by angiotensin-(1-9) in cultured rat cardiomyocytes

Background

The renin-angiotensin system (RAS) plays a pivotal role in regulating blood volume, systemic vascular resistance, and electrolyte balance, serving as a key component of cardiovascular health. Recent findings highlight the role of angiotensin II (Ang II) in inducing autophagy through angiotensin II receptor type 1 (AT1R). Autophagy, a process of self-degradation and turnover of cellular components, is a homeostatic response that eliminates superfluous materials. Abnormal autophagy promotes cardiomyocyte loss and is critical in hypertrophy and heart failure progression. The RAS's non-canonical axis, which includes the angiotensin 1-9 peptide [Ang-(1-9)], has an anti-hypertrophic effect in cardiomyocytes via an unknown mechanism. In the present study, we aimed to elucidate the effect of Ang-(1-9) on cardiomyocyte autophagy.

Methods

We isolated and cultured neonatal ventricular cardiomyocytes and then co-treated them with Ang-(1-9) in the presence of chloroquine (CQ), Ang-II, and chemical inhibitors of different signaling pathways. After treatment, total RNA and protein extracts were obtained to analyze the abundance of different autophagy markers. Likewise, cells were fixed, and autophagy was analyzed through epifluorescence microscopy.

Results

Our findings show that CQ leads to a reduction in autophagy markers, such as microtubule-associated protein 1 light chain 3-II (LC3-II) and total LC3, suggesting Ang-(1-9)'s regulatory role in basal autophagy levels. Furthermore, Ang-(1-9) opposes Ang-II-induced autophagy and induces the phosphorylation of the S234 residue of Beclin-1 (BCN1) via an angiotensin II receptor type 2 (AT2R)/Akt-dependent pathway.

Conclusions

This reduction of Ang-II-induced autophagy by Ang-(1-9) unveils a novel aspect of its action, potentially contributing to its cardioprotective effects.

Uncovering the Significance of JNK/AKT Axis in the Autophagic Regulation of Leishmania major Infection

The role of autophagy in host induced by infection of parasites of the Leishmania genus remains inadequately understood. Leishmania parasites modulate host macrophages to promote its survival by inducing autophagy response in the host cell. In this study, we conducted an investigation of L. major infection, focusing on host autophagy processes where we reconstructed two mathematical models elucidating autophagy induction and inhibition processes and its impact on parasite survival. Our models presented systems modulatory dynamics of the parasite-mediated host autophagy. Our work highlighted the pivotal role of signaling molecules associated with the immune response which included signaling induced by Toll-like receptor (TLR), specifically through regulation of JNK and AKT. Both molecules emerged as key regulators of host autophagy process, highlighting that JNK/AKT signaling axis may be a potential avenue for innovative therapeutic approaches in targeting leishmaniasis. Also, ATG16L complex was identified as a critical determinant in shaping the course of leishmanial infection through formation of autophagosomes. Through in vitro analyses in differentiated human monocyte cell line, we observed an increase in nitric oxide synthase (iNOS) concentration upon autophagy inhibition, while autophagy induction resulted in decreased iNOS concentration. This suggested that autophagy induction favors parasite survival in the host, potentially by providing a nutrient source that may be advantageous for the parasite. Inhibition of host autophagy promoted parasite elimination. Hence, our work proposed an avenue for strategically blocking host autophagy which enumerates a targeted approach for combating leishmaniasis.

Beclin-1: a therapeutic target at the intersection of autophagy, immunotherapy, and cancer treatment

The significant identification of Beclin-1's function in regulating autophagy flow signified a significant progression in our understanding of cellular operations. Beclin-1 acts as a scaffold for forming the PI3KC3 complex, controlling autophagy and cellular trafficking processes in a complicated way. This intricate protein has garnered considerable attention due to its substantial impact on the development of tumors. Strong evidence indicates Beclin-1 plays a critical role in controlling autophagy in various human cancer types and its intricate connection with apoptosis and ferroptosis. The potential of Beclin-1 as a viable target for cancer therapy is highlighted by its associations with key autophagy regulators such as AMPK, mTOR, and ATGs. Beclin-1 controls the growth and dissemination of tumors by autophagy. It also affects how tumors react to therapies such as chemotherapy and radiation therapy. The role of Beclin-1 in autophagy can influence apoptosis, depending on whether it supports cell survival or leads to cell death. Beclin-1 plays a crucial role in ferroptosis by increasing ATG5 levels, which in turn promotes autophagy-triggered ferroptosis. Finally, we analyzed the possible function of Beclin-1 in tumor immunology and drug sensitivity in cancers. In general, Beclin-1 has a significant impact on regulating autophagy, offering various potentials for medical intervention and altering our understanding of cancer biology.

Usnic Acid Targets 14-3-3 Proteins and Suppresses Cancer Progression by Blocking Substrate Interaction

The anticancer therapeutic effects of usnic acid (UA), a lichen secondary metabolite, have been demonstrated in vitro and in vivo. However, the mechanism underlying the anticancer effect of UA remains to be clarified. In this study, the target protein of UA was identified using a UA-linker-Affi-Gel molecule, which showed that UA binds to the 14-3-3 protein. UA binds to 14-3-3, causing the degradation of proteasomal and autophagosomal proteins. The interaction of UA with 14-3-3 isoforms modulated cell invasion, cell cycle progression, aerobic glycolysis, mitochondrial biogenesis, and the Akt/mTOR, JNK, STAT3, NF-κB, and AP-1 signaling pathways in colorectal cancer. A peptide inhibitor of 14-3-3 blocked or regressed the activity of UA and inhibited its effects. The results suggest that UA binds to 14-3-3 isoforms and suppresses cancer progression by affecting 14-3-3 targets and phosphorylated proteins.

Arabidopsis BECLIN1-induced autophagy mediates reprogramming in tapetal programmed cell death by altering the gross cellular homeostasis

In flowering plants, the tapetum degeneration in post-meiotic anther occurs through developmental programmed cell death (dPCD), which is one of the most critical and sensitive steps for the proper development of male gametophytes and fertility. Yet the pathways of dPCD, its regulation, and its interaction with autophagy remain elusive. Here, we report that high-level expression of Arabidopsis autophagy-related gene BECLIN1 (BECN1 or AtATG6) in the tobacco tapetum prior to their dPCD resulted in developmental defects. BECN1 induces severe autophagy and multiple cytoplasm-to-vacuole pathways, which alters tapetal cell reactive oxygen species (ROS)-homeostasis that represses the tapetal dPCD. The transcriptome analysis reveals that BECN1- expression caused major changes in the pathway, resulting in altered cellular homeostasis in the tapetal cell. Moreover, BECN1-mediated autophagy reprograms the execution of tapetal PCD by altering the expression of the key developmental PCD marker genes: SCPL48, CEP1, DMP4, BFN1, MC9, EXI1, and Bcl-2 member BAG5, and BAG6. This study demonstrates that BECN1-mediated autophagy is inhibitory to the dPCD of the tapetum, but the severity of autophagy leads to autophagic death in the later stages. The delayed and altered mode of tapetal degeneration resulted in male sterility.

Multiple forms of cell death: A focus on the PI3K/AKT pathway

Cell death is a natural biological process that occurs in living organisms. Since 1963, extensive research has shed light on the occurrence, progress, and final outcome of cell death. According to different cell phenotypes, it is classified into different types, including apoptosis, pyroptosis, necroptosis, autophagy, ferroptosis, cuproptosis, and so on. However, regardless of the form of cell death, what we ultimately expect is the disappearance of abnormal cells, such as tumor cells, while normal cells survive. As a result, it is vital to investigate the details of cell death, including death triggers, potent regulators, and executioners. Although significant progress has been made in understanding molecular pathways of cell death, many aspects remain unclear because of the complex regulatory networks in cells. Among them, the phosphoinositide-3-kinase (PI3K)/protein kinase B(AKT) pathway is discovered to be a crucial regulator of the cell death process. AKT, as a proto-oncogene, has become a major focus of attention in the medical community due to its role in regulating a multiplicity of cellular functions counting metabolism, immunity, proliferation, survival, transcription, and protein synthesis. Here, we explored the connection between the PI3K/AKT pathway and cell death, aiming to enhance our comprehension of the mechanism underlying this process. Such knowledge may pave the way for the subsequent development of more effective disease treatments, such as finding suitable targets for drug intervention.

Endoplasmic Reticulum Stress in Chronic Obstructive Pulmonary Disease: Mechanisms and Future Perspectives

The endoplasmic reticulum (ER) is an integral organelle for maintaining protein homeostasis. Multiple factors can disrupt protein folding in the lumen of the ER, triggering ER stress and activating the unfolded protein response (UPR), which interrelates with various damage mechanisms, such as inflammation, apoptosis, and autophagy. Numerous studies have linked ER stress and UPR to the progression of chronic obstructive pulmonary disease (COPD). This review focuses on the mechanisms of other cellular processes triggered by UPR and summarizes drug intervention strategies targeting the UPR pathway in COPD to explore new therapeutic approaches and preventive measures for COPD.