Structural and Ultrastructural Analysis of the Multiple Myeloma Cell Niche and a Patient-Specific Model of Plasma Cell Dysfunction

Autophagy-related mechanisms for treatment of multiple myeloma

Multiple myeloma (MM) is a type of hematological cancer that occurs when B cells become malignant. Various drugs such as proteasome inhibitors, immunomodulators, and compounds that cause DNA damage can be used in the treatment of MM. Autophagy, a type 2 cell death mechanism, plays a crucial role in determining the fate of B cells, either promoting their survival or inducing cell death. Therefore, autophagy can either facilitate the progression or hinder the treatment of MM disease. In this review, autophagy mechanisms that may be effective in MM cells were covered and evaluated within the contexts of unfolded protein response (UPR), bone marrow microenvironment (BMME), drug resistance, hypoxia, DNA repair and transcriptional regulation, and apoptosis. The genes that are effective in each mechanism and research efforts on this subject were discussed in detail. Signaling pathways targeted by new drugs to benefit from autophagy in MM disease were covered. The efficacy of drugs that regulate autophagy in MM was examined, and clinical trials on this subject were included. Consequently, among the autophagy mechanisms that are effective in MM, the most suitable ones to be used in the treatment were expressed. The importance of 3D models and microfluidic systems for the discovery of new drugs for autophagy and personalized treatment was emphasized. Ultimately, this review aims to provide a comprehensive overview of MM disease, encompassing autophagy mechanisms, drugs, clinical studies, and further studies.

Autophagy: A Potential Therapeutic Target to Tackle Drug Resistance in Multiple Myeloma

Multiple myeloma (MM) is the second most prevalent hematologic malignancy. In the past few years, the survival of MM patients has increased due to the emergence of novel drugs and combination therapies. Nevertheless, one of the significant obstacles in treating most MM patients is drug resistance, especially for individuals who have experienced relapses or developed resistance to such cutting-edge treatments. One of the critical processes in developing drug resistance in MM is autophagic activity, an intracellular self-digestive process. Several possible strategies of autophagy involvement in the induction of MM-drug resistance have been demonstrated thus far. In multiple myeloma, it has been shown that High mobility group box protein 1 (HMGB1)-dependent autophagy can contribute to drug resistance. Moreover, activation of autophagy via proteasome suppression induces drug resistance. Additionally, the effectiveness of clarithromycin as a supplemental drug in treating MM has been reported recently, in which autophagy blockage is proposed as one of the potential action mechanisms of CAM. Thus, a promising therapeutic approach that targets autophagy to trigger the death of MM cells and improve drug susceptibility could be considered. In this review, autophagy has been addressed as a survival strategy crucial for drug resistance in MM.

Autophagy and the Bone Marrow Microenvironment: A Review of Protective Factors in the Development and Maintenance of Multiple Myeloma

The role of the unfolded protein response (UPR) in plasma cells (PC) and their malignant multiple myeloma (MM) counterparts is a well described area of research. The importance of autophagy in these cells, as well as the interplay between autophagy and the UPR system, has also been well studied. In this review, we will discuss the relationship between these two cellular responses and how they can be utilized in MM to account for the high levels of monoclonal immunoglobulin (Ig) protein synthesis that is characteristic of this disease. Interactions between MM cells and the bone marrow (BM) microenvironment and how MM cells utilize the UPR/autophagy pathway for their survival. These interacting pathways form the foundation for the mechanism of action for bortezomib, a proteasome inhibitor used to modify the progression of MM, and the eventual drug resistance that MM cells develop. One important resistance pathway implicated in MM progression is caspase 10 which attenuates autophagy to maintain its prosurvival function and avoid cell death. We lay a groundwork for future research including 3D in vitro models for better disease monitoring and personalized treatment. We also highlight pathways involved in MM cell survival and drug resistance that could be used as new targets for effective treatment.