VLA-4 Induces Chemoresistance of T Cell Acute Lymphoblastic Leukemia Cells via PYK2-Mediated Drug Efflux

Focal adhesion kinase as a new player in the biology of onco-hematological diseases: the starting evidence

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase mainly found in the focal adhesion regions of the plasma membrane and it has a crucial role in migration and the remodeling of cellular morphology. FAK is also linked to several aspects of cancer biology, from cytokine production to angiogenesis, drug resistance, invasion, and metastasis, as well as epithelial-to-mesenchymal transition. The gene locus of FAK is frequently amplified in several human tumors, thus causing FAK overexpression in several cancers. Furthermore, FAK can influence extracellular matrix production and exosome secretion through cancer-associated fibroblasts, thus it has an important role in tumor microenvironment regulation. Although the role of FAK in solid tumors is well known, its importance in onco-hematological diseases remains poorly explored. This review collects studies related to FAK significance in onco-hematological diseases and their microenvironments. Overall, the importance of FAK in blood tumors is increasingly evident, but further research is required to confirm it as a new therapeutic target in hematological contexts.

CD38/NAD+ glycohydrolase and associated antigens in chronic lymphocytic leukaemia: From interconnected signalling pathways to therapeutic strategies

Chronic lymphocytic leukaemia (CLL) is a heterogenous disease characterized by the accumulation of neoplastic CD5+/CD19+ B lymphocytes. The spreading of the leukaemia relies on the CLL cell's ability to survive in the blood and migrate to and proliferate within the bone marrow and lymphoid tissues. Some patients with CLL are either refractory to the currently available therapies or relapse after treatment; this emphasizes the need for novel therapeutic strategies that improving clinical responses and overcome drug resistance. CD38 is a marker of a poor prognosis and governs a set of survival, proliferation and migration signals that contribute to the pathophysiology of CLL. The literature data evidence a spatiotemporal association between the cell surface expression of CD38 and that of other CLL antigens, such as the B-cell receptor (BCR), CD19, CD26, CD44, the integrin very late antigen 4 (VLA4), the chemokine receptor CXCR4, the vascular endothelial growth factor receptor-2 (VEGF-R2), and the neutrophil gelatinase-associated lipocalin receptor (NGAL-R). Most of these proteins contribute to CLL cell survival, proliferation and trafficking, and cooperate with CD38 in multilayered signal transduction processes. In general, these antigens have already been validated as therapeutic targets in cancer, and a broad repertoire of specific monoclonal antibodies and derivatives are available. Here, we review the state of the art in this field and examine the therapeutic opportunities for cotargeting CD38 and its partners in CLL, e.g. by designing novel bi-/trispecific antibodies.

GARNL3 identified as a crucial target for overcoming temozolomide resistance in EGFRvIII-positive glioblastoma

OBJECT

Amplification of the epidermal growth factor receptor (EGFR) and its active mutant type III (EGFRvIII), frequently occurr in glioblastoma (GBM), contributing to chemotherapy and radiation resistance in GBM. Elucidating the underlying molecular mechanism of temozolomide (TMZ) resistance in EGFRvIII GBM could offer valuable insights for cancer treatment.

METHODS

To elucidate the molecular mechanisms underlying EGFRvIII-mediated resistance to TMZ in GBM, we conducted a comprehensive analysis using Gene Expression Omnibus and The cancer genome atlas (TCGA) databases. Initially, we identified common significantly differentially expressed genes (DEGs) and prioritized those correlating significantly with patient prognosis as potential downstream targets of EGFRvIII and candidates for drug resistance. Additionally, we analyzed transcription factor expression changes and their correlation with candidate genes to elucidate transcriptional regulatory mechanisms. Using estimate method and databases such as Tumor IMmune Estimation Resource (TIMER) and CellMarker, we assessed immune cell infiltration in TMZ-resistant GBM and its relationship with candidate gene expression. In this study, we examined the expression differences of candidate genes in GBM cell lines following EGFRvIII intervention and in TMZ-resistant GBM cell lines. This preliminary investigation aimed to verify the regulatory impact of EGFRvIII on candidate targets and its potential involvement in TMZ resistance in GBM.

RESULTS

Notably, GTPase Activating Rap/RanGAP Domain Like 3 (GARNL3) emerged as a key DEG associated with TMZ resistance and poor prognosis, with reduced expression correlating with altered immune cell profiles. Transcription factor analysis suggested Epiregulin (EREG) as a putative upstream regulator of GARNL3, linking it to EGFRvIII-mediated TMZ resistance. In vitro experiments confirmed EGFRvIII-mediated downregulation of GARNL3 and decreased TMZ sensitivity in GBM cell lines, further supported by reduced GARNL3 levels in TMZ-resistant GBM cells.

CONCLUSION

GARNL3 downregulation in EGFRvIII-positive and TMZ-resistant GBM implicates its role in TMZ resistance, suggesting modulation of EREG/GARNL3 signaling as a potential therapeutic strategy.

Imaging Very Late Antigen-4 on MOLT4 Leukemia Tumors with Cysteine Site-Specific 89Zr-Labeled Natalizumab Immuno-Positron Emission Tomography

Very late antigen-4 (VLA4; CD49d) is a promising immune therapy target in treatment-resistant leukemia and multiple myeloma, and there is growing interest in repurposing the humanized monoclonal antibody (Ab), natalizumab, for this purpose. Positron emission tomography with radiolabeled Abs (immuno-PET) could facilitate this effort by providing information on natalizumab's in vivo pharmacokinetic and target delivery properties. In this study, we labeled natalizumab with 89Zr specifically on sulfhydryl moieties via maleimide-deferoxamine conjugation. High VLA4-expressing MOLT4 human T cell acute lymphoblastic leukemia cells showed specific 89Zr-natalizumab binding that was markedly blocked by excess Ab. In nude mice bearing MOLT4 tumors, 89Zr-natalizumab PET showed high-contrast tumor uptake at 7 days postinjection. Biodistribution studies confirmed that uptake was the highest in MOLT4 tumors (2.22 ± 0.41%ID/g) and the liver (2.33 ± 0.76%ID/g), followed by the spleen (1.51 ± 0.42%ID/g), while blood activity was lower at 1.12 ± 0.21%ID/g. VLA4-specific targeting in vivo was confirmed by a 58.1% suppression of tumor uptake (0.93 ± 0.15%ID/g) when excess Ab was injected 1 h earlier. In cultured MOLT4 cells, short-term 3 day exposure to the proteasome inhibitor bortezomib (BTZ) did not affect the α4 integrin level, but BTZ-resistant cells that survived the treatment showed increased α4 integrin expression. When the effects of BTZ treatment were tested in mice, there was no change of the α4 integrin level or 89Zr-natalizumab uptake in MOLT4 leukemia tumors, which underscores the complexity of tumor VLA4 regulation in vivo. In conclusion, 89Zr-natalizumab PET may be useful for noninvasive monitoring of tumor VLA4 and may assist in a more rational application of Ab-based therapies for hematologic malignancies.

WDR54 exerts oncogenic roles in T-cell acute lymphoblastic leukemia

WDR54 has been recently identified as a novel oncogene in colorectal and bladder cancers. However, the expression and function of WDR54 in T-cell acute lymphoblastic leukemia (T-ALL) were not reported. In this study, we investigated the expression of WDR54 in T-ALL, as well as its function in T-ALL pathogenesis using cell lines and T-ALL xenograft. Bioinformatics analysis indicated high mRNA expression of WDR54 in T-ALL. We further confirmed that the expression of WDR54 was significantly elevated in T-ALL. Depletion of WDR54 dramatically inhibited cell viability and induced apoptosis and cell cycle arrest at S phase in T-ALL cells in vitro. Moreover, knockdown of WDR54 impeded the process of leukemogenesis in a Jurkat xenograft model in vivo. Mechanistically, the expression of PDPK1, phospho-AKT (p-AKT), total AKT, phospho-ERK (p-ERK), Bcl-2 and Bcl-xL were downregulated, while cleaved caspase-3 and cleaved caspase-9 were upregulated in T-ALL cells with WDR54 knockdown. Additionally, RNA-seq analysis indicated that WDR54 might regulate the expression of some oncogenic genes involved in multiple signaling pathways. Taken together, these findings suggest that WDR54 may be involved in the pathogenesis of T-ALL and serve as a potential therapeutic target for the treatment of T-ALL.

T Cells Chemotaxis Migration Studies with a Multi-Channel Microfluidic Device

Immune surveillance is dependent on lymphocyte migration and targeted recruitment. This can involve different modes of cell motility ranging from random walk to highly directional environment-guided migration driven by chemotaxis. This study protocol describes a flow-based microfluidic device to perform quantitative multiplex cell migration assays with the potential to investigate in real time the migratory response of T cells at the population or single-cell level. The device also allows for subsequent in situ fixation and direct fluorescence analysis of the cells in the microchannel.

Mechanisms of Immunosuppressive Tumor Evasion: Focus on Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is a malignancy with high heterogeneity in its biological features and treatments. Although the overall survival (OS) of patients with ALL has recently improved considerably, owing to the application of conventional chemo-therapeutic agents, approximately 20% of the pediatric cases and 40-50% of the adult patients relapse during and after the treatment period. The potential mechanisms that cause relapse involve clonal evolution, innate and acquired chemoresistance, and the ability of ALL cells to escape the immune-suppressive tumor response. Currently, immunotherapy in combination with conventional treatment is used to enhance the immune response against tumor cells, thereby significantly improving the OS in patients with ALL. Therefore, understanding the mechanisms of immune evasion by leukemia cells could be useful for developing novel therapeutic strategies.