Aldehyde biphenyl chalcones induce immunogenic apoptotic-like cell death and are promising new safe compounds against a wide range of hematologic cancers

Stimulators of immunogenic cell death for cancer therapy: focusing on natural compounds

A growing body of evidence indicates that the anticancer effect of the immune system can be activated by the immunogenic modulation of dying cancer cells. Cancer cell death, as a result of the activation of an immunomodulatory response, is called immunogenic cell death (ICD). This regulated cell death occurs because of increased immunogenicity of cancer cells undergoing ICD. ICD plays a crucial role in stimulating immune system activity in cancer therapy. ICD can therefore be an innovative route to improve anticancer immune responses associated with releasing damage-associated molecular patterns (DAMPs). Several conventional and chemotherapeutics, as well as preclinically investigated compounds from natural sources, possess immunostimulatory properties by ICD induction. Natural compounds have gained much interest in cancer therapy owing to their low toxicity, low cost, and inhibiting cancer cells by interfering with different mechanisms, which are critical in cancer progression. Therefore, identifying natural compounds with ICD-inducing potency presents agents with promising potential in cancer immunotherapy. Naturally derived compounds are believed to act as immunoadjuvants because they elicit cancer stress responses and DAMPs. Acute exposure to DAMP molecules can activate antigen-presenting cells (APCs), such as dendritic cells (DCs), which leads to downstream events by cytotoxic T lymphocytes (CTLs) and natural killer cells (NKs). Natural compounds as inducers of ICD may be an interesting approach to ICD induction; however, parameters that determine whether a compound can be used as an ICD inducer should be elucidated. Here, we aimed to discuss the impact of multiple ICD inducers, mainly focusing on natural agents, including plant-derived, marine molecules, and bacterial-based compounds, on the release of DAMP molecules and the activation of the corresponding signaling cascades triggering immune responses. In addition, the potential of synthetic agents for triggering ICD is also discussed.

Novel anthraquinone derivatives trigger endoplasmic reticulum stress response and induce apoptosis

Background: Endoplasmic reticulum (ER) stress is a therapeutic target in cancer given its regulation of bioenergetics and cell death. Methodology & results: We synthesized 14 ER stress-triggered anthraquinone derivatives by introducing an amino group at the 3-position side chain of the lead compound obtained previously. Most of the anthraquinone derivatives exhibited good antitumor activity due to their ability to induce ER damage through cytoplasmic vacuoles. The mechanisms of ER stress caused by compound KA-4c were related to increasing the expression levels of the ATF6 and Bip proteins and upregulating CHOP and cleaved PARP. Conclusion: Compound KA-4c triggers ER stress response and induces apoptosis via the ATF6-CHOP signaling pathway.

ER Stress and Unfolded Protein Response in Leukemia: Friend, Foe, or Both?

The unfolded protein response (UPR) is an evolutionarily conserved adaptive signaling pathway triggered by a stress of the endoplasmic reticulum (ER) lumen compartment, which is initiated by the accumulation of unfolded proteins. This response, mediated by three sensors-Inositol Requiring Enzyme 1 (IRE1), Activating Transcription Factor 6 (ATF6), and Protein Kinase RNA-Like Endoplasmic Reticulum Kinase (PERK)—allows restoring protein homeostasis and maintaining cell survival. UPR represents a major cytoprotective signaling network for cancer cells, which frequently experience disturbed proteostasis owing to their rapid proliferation in an usually unfavorable microenvironment. Increased basal UPR also participates in the resistance of tumor cells against chemotherapy. UPR activation also occurs during hematopoiesis, and growing evidence supports the critical cytoprotective role played by ER stress in the emergence and proliferation of leukemic cells. In case of severe or prolonged stress, pro-survival UPR may however evolve into a cell death program called terminal UPR. Interestingly, a large number of studies have revealed that the induction of proapoptotic UPR can also strongly contribute to the sensitization of leukemic cells to chemotherapy. Here, we review the current knowledge on the consequences of the deregulation of UPR signaling in leukemias and their implications for the treatment of these diseases.