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Targeting conditioned media dependencies and FLT-3 in chronic lymphocytic leukemia

ABSTRACT: The importance of the stromal microenvironment in chronic lymphocytic leukemia (CLL) pathogenesis and drug resistance is well established. Despite recent advances in CLL therapy, identifying novel ways to disrupt interactions between CLL and its microenvironment may identify new combination partners for the drugs currently in use. To understand the role of microenvironmental factors on primary CLL cells, we took advantage of an observation that conditioned media (CM) collected from stroma was protective of CLL cells from spontaneous cell death ex vivo. The cytokine in the CM-dependent cells that most supports CLL survival in short term ex-vivo culture was CCL2. Pre-treatment of CLL cells with anti-CCL2 antibody enhanced venetoclax-mediated killing. Surprisingly, we found a group of CLL samples (9 of 23 cases) that are less likely to undergo cell death in the absence of CM support. Functional studies revealed that CM-independent (CMI) CLL cells are less sensitive to apoptosis than conventional stroma-dependent CLL. Additionally, a majority of the CMI CLL samples (80%) harbored unmutated IGHV. Bulk-RNA Seq analysis revealed upregulation of the focal adhesion and Ras signaling pathways in this group, along with expression of FLT3 and CD135 expression. Treatment with FLT3 inhibitors caused a significant reduction in cell viability among CMI samples. In summary, we were able to discriminate and target two biologically distinct subgroups of CLL based on CM dependence with distinct microenvironmental vulnerabilities.

ORGANISM(S): Homo sapiens

PROVIDER: GSE237907 | GEO | 2023/09/01

REPOSITORIES: GEO

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Project description:Breast cancers display a high degree of diversity between and within tumors due to variations in both tumor cells and non-malignant cells of the tumor microenvironment (TME). While most studies on the TME have focused on stroma located within the tumor mass, few studies have examined the peri-tumoral microenvironment, which extends beyond the tumor margins and includes the surrounding, benign-appearing tissues. Here, we examined the heterogeneity in tumors and peri-tumoral stroma from 10 ER+PR+HER2- invasive breast carcinomas, through multi-region transcriptomic profiling. Tumor samples were obtained from the center, superior, inferior, medial, and lateral (C, S, Inf, M, L) regions of each tumor. Peritumoral samples were obtained from four radial directions corresponding to the regions the tumor samples were collected from (S, Inf, M, L) and from three zones of increasing distances from the tumor margins (Zone 1: 1-3 cm, Zone 2: 3-5 cm, Zone 3: 5-7 cm). To represent the normal breast transcriptomic state, 5 non-directional samples were each obtained from 3 non-tumor bearing breasts (NTB) - 1 patient had undergone cosmetic reduction mammoplasty and 2 patients were germline BRCA2-mutation carriers who had undergone risk-reducing mammoplasties. Total RNA was isolated and microarray was performed using the human Clariom™ S Assay (ThermoFisher Scientific). In total, 144 transcriptomic profiles (47 Tumor, 82 peri-tumoral stroma, 15 NTB) were analyzed. Heterogeneity was observed both within and between the tumor samples, highlighting that unlike the histological classification, an individual tumor is often comprised of several molecular sub-types. Similarly, the peri-tumoral stroma was also heterogeneous, albeit independent of the tumor heterogeneity. Four distinct stromal clusters were noted, which differed in their molecular pathways and cell type composition. Among these, the adipose-enriched stroma that had inflammatory cancer-associated fibroblasts and innate immune cells was significantly associated with poorer overall survival, in contrast to the myofibroblast-enriched stroma. These data together suggest that the peri-tumoral heterogeneity may be an important determinant of the evolution and treatment of breast cancers.

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Targeting conditioned media dependencies and FLT-3 in chronic lymphocytic leukemia

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