ABSTRACT
The tumor suppressor gene von Hippel-Lindau (VHL) is involved in the development of sporadic clear-cell renal cell carcinoma (RCC). VHL interferes with angiogenesis and also controls cell adhesion and invasion. Therapies that target VHL-controlled genes are currently being evaluated in RCC patients. RCC is a immunogenic tumor and treatment with interleukin-2 (IL2) or interferon (IFN)-α results in regression in some patients. We used two renal tumor cell lines (RCC6 and RCC4) carrying VHL loss-of-function mutations to investigate the role of mutant VHL in susceptibility to natural killer (NK) cell-mediated lysis. The RCC6 and RCC4 cell lines were transfected with the wild-type gene to restore the function of VHL. The presence of the gene in RCC cells downregulated hypoxia-inducible factor (HIF)-1α and subsequently decreased vascular endothelial growth factor (VEGF) production. Relative to control transfectants and parental cells, pVHL-transfected cell lines activated resting and IL2-activated NK cells less strongly, as assessed by IFNγ secretion, NK degranulation and cell lysis. NKG2A, a human leukocyte antigen (HLA)-I-specific inhibitory NK receptor, controls the lysis of tumor targets. We show that HLA-I expression in RCC-pVHL cells is stronger than that in parental and controls cells, although the expression of activating receptor NK ligands remains unchanged. Blocking NKG2A/HLA-I interactions substantially increased lysis of RCC-pVHL, but had little effect on the lysis of VHL-mutated RCC cell lines. In addition, in response to IFNα, the exponential growth of RCC-pVHL was inhibited more than that of RCC-pE cells, indicating that VHL mutations may be involved in IFNα resistance. These results indicate that a decreased expression of HLA-I molecules in mutated VHL renal tumor cells sensitizes them to NK-mediated lysis. These results suggest that combined immunotherapy with anti-angiogenic drugs may be beneficial for patients with mutated VHL.
Subject(s)
Cytotoxicity, Immunologic/genetics , Killer Cells, Natural/metabolism , Mutation , Von Hippel-Lindau Tumor Suppressor Protein/genetics , Blotting, Western , Carcinoma, Renal Cell/genetics , Carcinoma, Renal Cell/immunology , Carcinoma, Renal Cell/pathology , Cell Hypoxia , Cell Line, Tumor , Cell Proliferation/drug effects , Cytotoxicity, Immunologic/immunology , Genetic Complementation Test , Histocompatibility Antigens Class I/metabolism , Humans , Hypoxia-Inducible Factor 1, alpha Subunit/genetics , Hypoxia-Inducible Factor 1, alpha Subunit/immunology , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Interferon-alpha/pharmacology , Interferon-gamma/immunology , Interferon-gamma/metabolism , Kidney Neoplasms/genetics , Kidney Neoplasms/immunology , Kidney Neoplasms/pathology , Killer Cells, Natural/immunology , NK Cell Lectin-Like Receptor Subfamily C/metabolism , RNA Interference , Transfection , Vascular Endothelial Growth Factor A/immunology , Vascular Endothelial Growth Factor A/metabolism , Von Hippel-Lindau Tumor Suppressor Protein/metabolismABSTRACT
The focus of this study was to investigate NK cell reconstitution early after hematopoietic stem cell transplantation (HSCT). We were particularly interested in acute myeloid leukemia (AML) since patients with this disease may display an altered NK cell function. The function and the phenotype of donor-derived NK cells obtained from 35 allografted patients 30 and 60 days after HSCT for AML or other-than-AML hematological malignancies has been assessed. NK functional status was investigated by measuring the degranulation capacity (externalization of CD107a) of NK cells against human K562. We also concomitantly determined the concentration of selected cytokines known to modulate NK function and/or receptor expression. At day 30, donor-derived AML and non-AML NK cells could efficiently degranulate when exposed to leukemic K562 targets. At day 60, we observed a reduced NK degranulation potential in AML patients only. Decreased NK activity in AML patients was concomitant to NKp46 and NKp30 down-regulation. AML NK cells were chronically exposed to low IL-2 levels following HSCT. TGF-beta(1) was undetectable in all patients. In AML, the functional activity of donor-derived NK cells is remarkable at day 30 but may strongly decrease two months after HSCT. Therefore, in this condition, early NK immune-modulation might improve HSCT outcome.
Subject(s)
Hematopoietic Stem Cell Transplantation , Killer Cells, Natural/immunology , Leukemia, Myeloid, Acute/immunology , Adolescent , Adult , Aged , Female , Humans , Leukemia, Myeloid, Acute/therapy , Male , Middle Aged , Phenotype , Tissue Donors , Treatment Outcome , Young AdultABSTRACT
ApoJ/Clusterin (CLU) is a heterodimeric protein localized in the nucleus, cytoplasm or secretory organelles and involved in cell survival and neoplastic transformation. Its function in human cancer is still highly controversial. In this study, we examined the prostate of mice in which CLU has been genetically inactivated. Surprisingly, we observed transformation of the prostate epithelium in the majority of CLU knockout mice. Either PIN (prostate intraepithelial neoplasia) or differentiated carcinoma was observed in 100 and 87% of mice with homozygous or heterozygous deletion of CLU, respectively. Crossing CLU knockout with TRAMP (prostate cancer prone) mice results in a strong enhancement of metastatic spread. Finally, CLU depletion causes tumourigenesis in female TRAMP mice, which are normally cancer free. Mechanistically, deletion of CLU induces activation of nuclear factor-kB, a potentially oncogenic transcription factor important for the proliferation and survival of prostate cells.
