Biomedical subjects

Ashani Weeraratna

Publications and source records attributed to Ashani Weeraratna.

3 recordsLinked to original sources

PubMed2024

Oncogene-induced matrix reorganization controls CD8+ T cell function in the soft-tissue sarcoma microenvironment.

CD8+ T cell dysfunction impedes antitumor immunity in solid cancers, but the underlying mechanisms are diverse and poorly understood. Extracellular matrix (ECM) composition has been linked to impaired T cell migration and enhanced tumor progression; however, impacts of individual ECM molecules on T cell function in the tumor microenvironment (TME) are only beginning to be elucidated. Upstream regulators of aberrant ECM deposition and organization in solid tumors are equally ill-defined. Therefore, we investigated how ECM composition modulates CD8+ T cell function in undifferentiated pleomorphic sarcoma (UPS), an immunologically active desmoplastic tumor. Using an autochthonous murine model of UPS and data from multiple human patient cohorts, we discovered a multifaceted mechanism wherein the transcriptional coactivator YAP1 promotes collagen VI (COLVI) deposition in the UPS TME. In turn, COLVI induces CD8+ T cell dysfunction and immune evasion by remodeling fibrillar collagen and inhibiting T cell autophagic flux. Unexpectedly, collagen I (COLI) opposed COLVI in this setting, promoting CD8+ T cell function and acting as a tumor suppressor. Thus, CD8+ T cell responses in sarcoma depend on oncogene-mediated ECM composition and remodeling.

CD8-Positive T-Lymphocytes↗

PubMed2006

Direct and indirect effects of retinoic acid on human Th2 cytokine and chemokine expression by human T lymphocytes.

BACKGROUND: Vitamin A (VA) deficiency induces a type 1 cytokine response and exogenously provided retinoids can induce a type 2 cytokine response both in vitro and in vivo. The precise mechanism(s) involved in this phenotypic switch are inconsistent and have been poorly characterized in humans. In an effort to determine if retinoids are capable of inducing Th2 cytokine responses in human T cell cultures, we stimulated human PBMCs with immobilized anti-CD3 mAb in the presence or absence of all-trans retinoic acid (ATRA) or 9-cis-RA. RESULTS: Stimulation of human PBMCs and purified T cells with ATRA and 9-cis-RA increased mRNA and protein levels of IL-4, IL-5, and IL-13 and decreased levels of IFN-gamma, IL-2, IL-12p70 and TNF-alpha upon activation with anti-CD3 and/or anti-CD28 mAbs. These effects were dose-dependent and evident as early as 12 hr post stimulation. Real time RT-PCR analysis revealed a dampened expression of the Th1-associated gene, T-bet, and a time-dependent increase in the mRNA for the Th2-associated genes, GATA-3, c-MAF and STAT6, upon treatment with ATRA. Besides Th1 and Th2 cytokines, a number of additional proinflammatory and regulatory cytokines including several chemokines were also differentially regulated by ATRA treatment. CONCLUSION: These data provide strong evidence for multiple inductive roles for retinoids in the development of human type-2 cytokine responses.

Adult↗

PubMed2002

Trk receptor inhibition induces apoptosis of proliferating but not quiescent human osteoblasts.

Prostate cancer frequently metastasizes to the skeleton, producing painful osteoblastic lesions, which are associated with significant morbidity and mortality. This bone tropism involves the bidirectional paracrine interactions between prostate cancer cells and osteoblasts. These interactions enhance prostate cancer cell survival and proliferation of osteoblasts. Therefore, agents that can induce apoptosis of prostate cancer cells and proliferating osteoblasts would be highly advantageous. Previously, we have documented that the unique survival pathway for prostate cancer cells involves a neurotrophin/Trk receptor autocrine pathway. The indocarbazole compounds, CEP-701 and CEP-751, are potent inhibitor of this Trk receptor survival signaling and thus selectively induces apoptosis of prostate cancer cells in various in vitro and in vivo models. In this study, we documented the effects of CEP-751 on the conditionally immortalized osteoblastic cell line, hFOB, in vitro. At the permissive temperature of 34 degrees C, these cells express large T antigen, inducing their continuous proliferation, whereas at 39 degrees C, T antigen is degraded and the cells stop proliferating without undergoing apoptosis. Trk receptors are expressed in hFOB cells, as determined both by reverse transcription-PCR and Western blots. These osteoblasts were shown to produce nerve growth factor and brain-derived neurotrophic factor but not neurotrophin-3, as measured by ELISA. hFOB osteoblasts, cultured at 34 degrees C, secreted significantly (P < 0.01) more brain-derived neurotrophic factor and nerve growth factor into the medium than hFOB cells cultured at 39 degrees C. Because the Trk/neurotrophin axis is present in both proliferating and quiescent (i.e., nonproliferating) osteoblasts, the effects of 48 h of exposure to various doses of CEP-751 on cell viability and apoptosis of hFOB cells were assessed by trypan blue exclusion assays and 4',6-diamidino-2-phenylindole nuclear staining. Cell viability and apoptosis of hFOB cells at 34 degrees C were significantly and dose-dependently decreased compared with untreated proliferating cells. In contrast, even the highest concentration of CEP-751 (200 nM) did not affect cell viability and apoptosis of quiescent hFOB cells cultured at 39 degrees C. This trk inhibition-induced cytotoxicity was confirmed using early-passage, proliferating normal (i.e., non-SV40-transformed) human osteoblasts, which also express Trk receptor protein. These combined results demonstrate that proliferating osteoblasts acquire a sensitivity to trk inhibition- induced apoptosis not shared with normally quiescent osteoblasts.

Antineoplastic Agents↗