miR-17-92 expression in differentiated T cells - implications for cancer immunotherapy.
BACKGROUND
Type-1 T cells are critical for effective anti-tumor immune responses. The recently discovered microRNAs (miRs) are a large family of small regulatory RNAs that control diverse aspects of cell function, including immune regulation. We identified miRs differentially regulated between type-1 and type-2 T cells, and determined how the expression of such miRs is regulated.


METHODS
We performed miR microarray analyses on in vitro differentiated murine T helper type-1 (Th1) and T helper type-2 (Th2) cells to identify differentially expressed miRs. We used quantitative RT-PCR to confirm the differential expression levels. We also used WST-1, ELISA, and flow cytometry to evaluate the survival, function and phenotype of cells, respectively. We employed mice transgenic for the identified miRs to determine the biological impact of miR-17-92 expression in T cells.


RESULTS
Our initial miR microarray analyses revealed that the miR-17-92 cluster is one of the most significantly over-expressed miR in murine Th1 cells when compared with Th2 cells. RT-PCR confirmed that the miR-17-92 cluster expression was consistently higher in Th1 cells than Th2 cells. Disruption of the IL-4 signaling through either IL-4 neutralizing antibody or knockout of signal transducer and activator of transcription (STAT)6 reversed the miR-17-92 cluster suppression in Th2 cells. Furthermore, T cells from tumor bearing mice and glioma patients had decreased levels of miR-17-92 when compared with cells from non-tumor bearing counterparts. CD4+ T cells derived from miR-17-92 transgenic mice demonstrated superior type-1 phenotype with increased IFN-gamma production and very late antigen (VLA)-4 expression when compared with counterparts derived from wild type mice. Human Jurkat T cells ectopically expressing increased levels of miR-17-92 cluster members demonstrated increased IL-2 production and resistance to activation-induced cell death (AICD).


CONCLUSIONS
The type-2-skewing tumor microenvironment induces the down-regulation of miR-17-92 expression in T cells, thereby diminishing the persistence of tumor-specific T cells and tumor control. Genetic engineering of T cells to express miR-17-92 may represent a promising approach for cancer immunotherapy.
Sasaki
Kotaro
K
Department of Immunology, University of Pittsburgh School of Medicine, PA 15213, USA.
Kohanbash
Gary
G
Hoji
Aki
A
Ueda
Ryo
R
McDonald
Heather A
HA
Reinhart
Todd A
TA
Martinson
Jeremy
J
Lotze
Michael T
MT
Marincola
Francesco M
FM
Wang
Ena
E
Fujita
Mitsugu
M
Okada
Hideho
H
D000818:Animals; D016923:Cell Death / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology; D006801:Humans; D007167:Immunotherapy / Q000379:methods*; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology; D007376:Interleukin-2 / Q000276:immunology; D015847:Interleukin-4 / Q000235:genetics / Q000276:immunology; D019169:Jurkat Cells; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D035683:MicroRNAs / Q000235:genetics / Q000276:immunology; D046228:Microarray Analysis; D009369:Neoplasms / Q000276:immunology / Q000628:therapy; D015398:Signal Transduction / Q000276:immunology; D018417:Th1 Cells / Q000166:cytology / Q000276:immunology / Q000502:physiology; D018418:Th2 Cells / Q000166:cytology / Q000276:immunology / Q000502:physiology
D007376:Interleukin-2; D035683:MicroRNAs; D015847:Interleukin-4; D007371:Interferon-gamma