Expression of Akt (protein kinase B) and its isoforms in malignant lymphomas.

Akt (protein kinase B) is a serine/threonine kinase involved in the regulation of cell survival signals. Akt is expressed in T- and B-lymphocytes and is activated in response to cytokine and antigen-receptor stimulation. Three isoforms of Akt have been identified, Akt-1, -2 and -3, but the expression pattern and specific functions of each have not yet been determined for many cell types. To determine whether Akt signaling is enhanced in human malignant lymphomas and to analyse the expression pattern of Akt isoforms in these neoplasms, Akt-1, -2 and -3 expression was studied in 38 cell lines derived from hematopoietic neoplasms, by RT-PCR and western blot analysis. The level of phosphorylated (active) Akt was also analysed in cell lines as well as in 72 human malignant non-Hodgkin's lymphoma tissues. The results suggest that there is constitutive activation of Akt in the majority of primary human lymphomas and hematopoietic cell lines and support its proposed key role in lymphoma cell survival.

An in vitro animal study of the biomechanical responses of anulus fibrosus with aging.

STUDY DESIGN: In vitro biomechanical tests were performed on aged (group A) and young (group B) porcine intervertebral discs. OBJECTIVES: The in vitro biomechanical responses of aged and young porcine intervertebral discs were measured under designated axial compressive loads and analyzed. SUMMARY OF BACKGROUND DATA: From the biomechanical point of view, the major biomechanical functions of intervertebral discs are to absorb and distribute external loadings. Although the histological observation of intervertebral discs on the effect of aging and related degeneration has been extensively studied and described, the changes in those biomechanical functions attributable to aging are still left to be studied. METHODS: Two groups were set for mechanical tests. Group A consisted of 24 motion segments obtained from female porcine lumbar (44.0 +/- 2.8-months old). The group B consisted of 30 motion segments from female porcine lumbar (6.2 +/- 1.3 months old). The specimens were chosen randomly from all levels. For the measurements of biomechanical responses, a pressure transducer was placed on anterior and posterolateral locations of anulus fibrosus. Morphological and histological observations were carried out to confirm any age-related changes in both groups. Intradiscal pressures and relaxation times were measured and calculated at points in the anulus fibrosus under designated axial compressive loads. RESULTS: Morphological and histological difference between group A and group B were confirmed with H&E staining and other measurements. Group A showed a lower ratio of nucleus pulposus area to total disc area than did group B. There was no significant difference in the intradiscal pressure between groups as measured in the anterior zone, except at an axial load of 740 N. However, a significant pressure difference was found in the posterolateral zone when the axial load was 542 N or greater (P < 0.05). At 740 N, the average relaxation time for group A was significantly longer than that for group B (P < 0.05). CONCLUSIONS: Differences in biomechanical responses between groups were confirmed. Group A was less flexible and slower at energy relaxation under axial loading. A larger proportion of the external load was taken by the posterolateral part of the degenerative discs. These results were consistent with clinical experiences: 1) most hernias are observed more often at the posterolateral side than other sides, and 2) the degeneration attributable to age reduces the function of absorbing and distribution of external loadings.

p53, K-ras, c-kit and beta-catenin gene mutations in sinonasal NK/T-cell lymphoma in Korea and Japan.

Mutations of p53, K-ras, c-kit, and beta-catenin gene were examined in 100 cases of sinonasal NK/T-cell lymphoma (NKTCL) from Korea and Japan. Age of patients ranged from 12 to 72 (median 41.0) in Korea and 27 to 82 (median 61.0) years in Japan. Gene mutations were analyzed on paraffin-embedded specimens by PCR-SSCP followed by direct sequencing. p53 is a well-known tumor suppressor gene. c-kit gene encodes a receptor tyrosine kinase, which plays a crucial role in proliferation and differentiation of hematopoietic stem cells. Mutations of K-ras and beta-catenin are frequently observed in cancers. Thirteen of 42 (31.0%) cases from Korea and 36 of 58 (62.1%) from Japan had p53 mutations, showing significant differences in the incidence of p53 mutation between two countries. Of the Japanese cases 18 (31.0%) had mutations in exon 4, while only 3 cases (7.1%) were found in Korea cases (p<0.01 by chi2 test). K-ras, c-kit and beta-catenin mutations were also found in higher incidence in Japanese cases. In conclusion, different frequency of p53 mutations with different pattern of exon involvement and difference in age of disease onset is evident between sinonasal NKTCL in Korea and Japan.

Gene expression profiling of cell lines derived from T-cell malignancies.

The expression profiles of eight cell lines derived from T-cell malignancies were compared to CD4-positive T-cells using cDNA microarray technology. Unsupervised hierarchical clustering of 4364 genes demonstrated substantial heterogeneity resulting in four distinct groups. While no genes were found to be uniformly up- or down-regulated across all cell lines, we observed 111 over-expressed genes (greater than two-fold) and 1118 down-regulated genes (greater than two-fold) in the lymphomas as a group when compared to CD4-positive T-cells. These included genes involved in cytokine signaling, cell adhesion, cytoskeletal elements, nuclear transcription factors, and known oncogenes and tumor suppressor genes. Quantitative fluorescent reverse transcription-polymerase chain reaction analysis demonstrated 70% concordance with the microarray results. While freshly isolated malignant cells may differ in their individual expression patterns relative to established cell lines from the same diagnoses, we feel that the variety of different lymphocytic cell lines that we examined provides a representative picture of the molecular pathogenesis of T-cell malignancies.