Cancer-associated fibroblasts in hematologic malignancies: elucidating roles and spotlighting therapeutic targets

Tuning the B-CLL microenvironment: evidence for BAG3 protein- mediated regulation of stromal fibroblasts activity

The Bcl2-associated athanogene-3 (BAG3) protein, a critical regulator of cellular survival, has been identified as a potential therapeutic target in various malignancies. This study investigates the role of BAG3 within stromal fibroblasts and its interaction with B-cell chronic lymphocytic leukemia (B-CLL) cells. Previous research demonstrated that BAG3 maintains the active state of pancreatic stellate cells (PSCs) and aids pancreatic ductal adenocarcinoma (PDAC) spread via cytokine release. To explore BAG3's role in bone marrow-derived stromal fibroblasts, BAG3 was silenced in HS-5 cells using siRNA. In co-culture experiments with PBMCs from B-CLL patients, BAG3 silencing in HS-5 cells increased apoptosis and decreased phosphorylation of BTK, AKT, and ERK in B-CLL cells, thus disrupting their pro-survival key signaling pathways. The observation of fibroblast-activated protein (FAP) positive cells in infiltrated bone marrow specimens co-expressing BAG3 further support the involvement of the protein in fibroblast-mediated tumor survival. Additionally, BAG3 appears to support B-CLL survival by modulating cytokine networks, including IL-10 and CXCL12, which are essential for leukemic cell survival and proliferation. A robust correlation between BAG3 expression and the levels of CXCL12 and IL-10 was observed in both co-cultures and patient specimens. These findings point out the need for a more in-depth comprehension of the intricate network of interactions within the tumor microenvironment and provide valuable insights for the selection of new potential therapeutic targets in the medical treatment of CLL.

Pathways to therapy resistance: The sheltering effect of the bone marrow microenvironment to multiple myeloma cells

Multiple Myeloma (MM) is a malignant expansion of plasma cells in the bone marrow (BM), resulting in a disease characterized by symptoms of end organ damage from light chain secretion, crowding of the BM, and bone lesions. Although the past two decades have been characterized by numerous novel therapies emerging, the disease remains incurable due to intrinsic or acquired drug resistance. A major player in MM's drug resistance arises from its intimate relationship with the BM microenvironment (BMME). Through stress-inducing conditions, soluble messengers, and physical adhesion to BM elements, the BMME activates numerous pathways in the myeloma cell. This not only propagates myeloma progression through survival and growth signals, but also specific mechanisms to circumvent therapeutic actions. In this review, we provide an overview of the BMME, the role of individual components in MM survival, and various therapy-specific resistance mechanisms reported in the literature.

TME-Related Biomimetic Strategies Against Cancer

The tumor microenvironment (TME) plays an important role in various stages of tumor generation, metastasis, and evasion of immune monitoring and treatment. TME targeted therapy is based on TME components, related pathways or active molecules as therapeutic targets. Therefore, TME targeted therapy based on environmental differences between TME and normal cells has been widely studied. Biomimetic nanocarriers with low clearance, low immunogenicity, and high targeting have enormous potential in tumor treatment. This review introduces the composition and characteristics of TME, including cancer‑associated fibroblasts (CAFs), extracellular matrix (ECM), tumor blood vessels, non-tumor cells, and the latest research progress of biomimetic nanoparticles (NPs) based on TME. It also discusses the opportunities and challenges of clinical transformation of biomimetic nanoparticles.