Deletion or lack of expression of CDKN2 (CDK4I/MTS1/INK4A) and MTS2 (INK4B) in acute lymphoblastic leukemia cell lines reflects the phenotype of the uncultured primary leukemia cells.

The CDKN2 gene has been recently localized to a chromosomal region found to be deleted in leukemias and solid tumors. CDKN2 encodes a 16 kDa protein product (p16INK4A), which functions as a specific inhibitor or the cyclin-dependent kinases 4 and 6. There have been many reports indicating a higher frequency of deletions of the CDKN2 gene in a variety of tumor cell lines, in comparison to primary tumors. These studies raise the possibility that deletions of CDKN2 may be a rare event in primary tumors, and in fact arise in vitro, during the establishment of permanent cell lines. To address this issue, we determined whether the CDKN2 gene deletions found in acute lymphoblastic leukemia (ALL) cell lines are also detected in the primary leukemia samples. Eleven cell lines were identified which had available frozen primary samples of their original leukemic tissue. Five out of 11 of these cell lines, as well as their primary samples had homozygous CDKN2 deletions. The remaining six cell lines and their primary samples retained at least one copy of the CDKN2 gene. Of the six CDKN2+ cell lines, five expressed CDKN2 mRNA, but only one of these expressed the p16 protein product (as did its primary sample). Our results indicate that CDKN2 deletions present in the studied ALL cell lines arose in the primary leukemic cells, and not during cell line establishment or prolonged in vitro culture.

Growth inhibition of B-cell precursor acute lymphoblastic leukemia cell lines by monocytes: a role for prostaglandin E2.

Leukemic cell lines have proven invaluable in the molecular analysis of recurring chromosomal translocations but the optimal methods for leukemia cell line establishment are unknown. During in vitro culture, most B-cell precursor acute lymphoblastic leukemia (BCP-ALL) cells die within 1 week at least partially mediated by inhibitors elaborated by peripheral blood mononuclear cells (PB MNCs) present within the leukemia sample. In experiments reported here, cyclooxygenase inhibitors (indomethacin and meclofenamic acid) blocked the PB MNC-mediated inhibition of BCP-ALL proliferation. Also, prostaglandin E2 (PGE2) was detected in supernatants from PB MNC cultures. When PGE2 was mixed directly with BCP-ALL cells, proliferation decreased significantly. Under the culture conditions used, PB MNCs secreted PGE2 which appears to be one of the major inhibitors of BCP-ALL growth in vitro.

Myelodysplastic syndrome with t(5;12)(q31;p12-p13) and eosinophilia: a pediatric case with review of literature.

PURPOSE: Myelodysplastic syndrome with chromosomal translocation t(5;12)(q31-33;p12-13) and eosinophilia is a new entity recently described. Nine cases have been described in adults. We report the first pediatric case with a long follow-up (7 years). PATIENTS AND METHODS: An 8-year-old girl presented with hyperleukocytosis, eosinophilia, and no clinical symptoms. Bone marrow investigations revealed myeloid hyperplasia and clonal chromosomal translocation t(5;12)(q31;p12-13). No treatment was prescribed, but 4 years later the white blood cell count reached 144 X 10(9)/L with immature myeloid cells and splenic enlargement. Hydroxyurea chemotherapy led to a hematopoietic remission. The patient is now 16 years old and well, >7 years after the initial diagnosis. RESULTS: The association: myelodysplastic syndrome, eosinophilia and translocation t(5;12)(q31-33;p12-13), seems to be a specific hematologic disorder. Study of cases previously reported in the literature shows the most important characteristics of this disease. However, there are still a number of questions about the disease itself (especially its treatment) and the significance of the chromosomal abnormalities. CONCLUSION: This case seems to be the first report of the disease in a child and has had the longest follow-up. Other data should be collected to improve our knowledge of this hematopoietic disorder.