Generation of a Genetically Engineered Aggressive Nk-Cell Leukemia Cell Line with Stable IL2 Expression.

Introduction: Aggressive NK-cell leukemia (ANKL) is a highly aggressive disease with extremely poor prognosis. A few malignant NK cell lines reflecting ANKL biology have been generated; however, these NK cell lines require the inclusion of exogeneous IL2 in the culture medium continuously, which increases the cost of cell culture significantly. Methods: IL2 coding sequenced was cloned into MSCV-IRES-YFP (PMIY) vector by directional PCR-cloning. IL2 was ectopically expressed in KHYG1 cell line through retroviral transduction. The transduced cells were cultured in limiting IL2 concentrations during which they were quantified with flow cytometry in regular time intervals to track the transduced population. IL2 transduced KHYG1 cells were then sorted to generate IL2-KHYG1 cells. PRDM1 was ectopically expressed in IL2-KHYG1 cells through retroviral transduction. Trypan blue count was performed to test proliferation of IL2-KYHG1 cells in the absence of IL2. Results: IL2-KHYG1 cells were enriched (from ~7% to ~16% YFP+ cells) during cell culture in limiting (6.25IU) IL2 concentrations. Complete removal of IL2 further enriched the transduced portion to 27% YFP-positivity, which did not increase with additional culturing. IL2 expressing KHYG1 cells were further enriched by sorting transduced IL2-KHYG1 cells with high level IL2 expression. IL2-KHYG1 cells survived and continued to grow without IL2. IL2-KHYG1 cells were transduced successfully using a PRDM1 construct having GFP as a marker under cell culture conditions having no IL2. Conclusion: IL2-KHYG1 cell line may decrease the cost associated with culturing ANKL cell lines, and it may facilitate in vitro investigation of the molecular basis of this malignancy.

Clinical implication of genome-wide profiling in diffuse large B-cell lymphoma and other subtypes of B-cell lymphoma.

The differentiation of lymphoid cells is tightly regulated by transcription factors at various stages during their development. During the maturation processes, different genomic alterations or aberrations such as chromosomal translocation, mutation and deletions may occur that can eventually result in distinct biological and clinical tumors. The different differentiation stages create heterogeneity in lymphoid malignancies, which can complicate the diagnosis. The initial diagnostic scheme for lymphoid diseases was coined by Rappaport followed by Revised European and American Classification of Lymphoid Neoplasms (REAL) and World Health Organization (WHO) classifications. These classification methods were based on histological, immunophenotypic and cytogenetic markers and widely accepted by pathologists and oncologists worldwide. During last several decades, great progress has been made in understanding the etiology, pathogenesis and molecular biology of malignant lymphoma. However, detailed knowledge in the molecular mechanism of lymphomagenesis is largely unknown. New therapeutic protocols based on the new classification have been on clinical trials, but with little success. Therefore, it is imperative to understand the basic biology of the tumor at molecular level. One important approach will be to measure the activity of the tumor genome and this can partly be achieved by the measurement of whole cellular mRNA. One of the key technologies to perform a high-throughput analysis is DNA microarray technology. The genome-wide transcriptional measurement, also called gene expression profile (GEP) can accurately define the biological phenotype of the tumor. In this review, important discoveries made by genome-wide GEP in understanding the biology of lymphoma and additionally the diagnostic and prognostic value of microarrays are discussed.