ABSTRACT
Differential expression of molecules in chronic lymphocytic leukemia (CLL) may define prognostic markers and suitable targets for immunotherapy. Expression of the tumor-associated antigen (TAA) RHAMM (receptor for hyaluronic acid-mediated motility) as well as RHAMM splicing variants was assessed in series of 72 CLL patients. Quantitative reverse transcriptase PCR showed higher RHAMM expression in high-risk CLL patients, as well as in the advanced stages of the disease. CLL cases with a higher RHAMM expression showed a significantly shorter median treatment-free survival. Among patients with mutated immunoglobulin heavy chain genes, an analysis of RHAMM expression enabled to distinguish subgroup of patients with favorable prognosis. In lymph nodes, RHAMM staining correlated with a higher Ki-67 index and CD40L expression. Functionally, stimulation with CD40L enhanced RHAMM expression in CLL. We further characterized RHAMM-specific CD8(+) T cells in patients with CLL, as the expression of TAAs might influence the clinical outcome by the means of immune reactions. The cytotoxic potential of RHAMM-specific T cells was shown against target cells bearing RHAMM-derived epitope as well as against CLL cells expressing RHAMM. In conclusion, RHAMM expression appears to be of prognostic value, as well as may reflect the proliferative capacity of CLL cells, and might therefore represent interesting target for immunotherapy.
Subject(s)
Extracellular Matrix Proteins/physiology , Hyaluronan Receptors/physiology , Leukemia, Lymphocytic, Chronic, B-Cell/metabolism , Neoplasm Proteins/physiology , Adult , Aged , Aged, 80 and over , CD40 Ligand/analysis , CD40 Ligand/pharmacology , CD8-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/pathology , Cell Division , Cytotoxicity, Immunologic , Disease Progression , Disease-Free Survival , Extracellular Matrix Proteins/analysis , Female , Humans , Hyaluronan Receptors/analysis , Immunoglobulin Heavy Chains/genetics , Leukemia, Lymphocytic, Chronic, B-Cell/genetics , Leukemia, Lymphocytic, Chronic, B-Cell/mortality , Leukemia, Lymphocytic, Chronic, B-Cell/pathology , Male , Middle Aged , Neoplasm Proteins/analysis , Prognosis , Protein Isoforms/analysis , Protein Isoforms/physiology , RNA Splicing , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
In mantle cell lymphoma (MCL), the translocation t(11;14) is considered the cytogenetic hallmark of the disease. Recently, however, deletion of the chromosomal region 11q22-q23 has been identified as a frequent event in this type of cancer, indicating the existence of a pathogenically relevant tumor suppressor gene in this region. The deleted segment contains the ATM (ataxia telangiectasia mutated) gene. ATM is an interesting candidate as a tumor suppressor gene because constitutive inactivation of the gene predisposes ataxia telangiectasia patients to lymphoid malignancies. To assess the potential involvement of the gene in MCL lymphomagenesis, we performed mutation analysis of ATM in 12 sporadic cases of MCL, 7 of them with a deletion of one ATM gene copy, by using single-strand conformation polymorphism analysis of reverse transcription-PCR-amplified mRNA and subsequent DNA sequencing. In all seven cases containing a deletion of one ATM allele, a point mutation in the remaining allele was detected, which resulted in aberrant transcript splicing, truncation, or alteration of the protein. In addition, biallelic ATM mutations were identified in two MCLs that did not contain 11q deletions. Interestingly, in three cases analyzed, the ATM mutations detected in the tumor cells were not present in nonmalignant cells, demonstrating their somatic rather than germ-line origin. The inactivation of both alleles of the ATM gene by deletion and deleterious point mutation in the majority of cases analyzed indicates that ATM plays a role in the initiation and/or progression of MCL.
