RESUMO
Tetracycline-3 (4-dedimethylamino sancycline, COL-3) is a non-antibiotic tetracycline derivative. COL-3 exerts potent anti-metalloproteinase activity and its antitumor effects have been reported both in vitro and in vivo. In this study, we investigated the mechanisms of COL-3-induced cytotoxicity in a chronic myeloid leukemia cell line, K562, characterized by the BCR-ABL fusion protein. COL-3 induced K562 cell death in a concentration-dependent manner with an IC50 of 10.8 µg/mL and exhibited features of both apoptosis and necrosis. However, flow cytometry analysis revealed that necrotic cells dominated over the early and late apoptotic cells upon treatment with COL-3. Transmission electron microscopy analysis in combination with Western blotting (WB) analysis revealed early mitochondrial swelling accompanied by the early release of cytochrome c and truncated apoptosis inducing factor (tAIF). In addition, ultrastructural changes were detected in the endoplasmic reticulum (ER). COL-3 affected the levels of glucose-regulated protein-94 (GRP94) and resulted in m-calpain activation. DNA double strand breaks as a signature for DNA damage was also confirmed using an antibody against γH2AX. WB analyses did not demonstrate caspase activation, while Bcl-xL protein remained unaffected. In conclusion, COL-3-induced cell death involves DNA damage as well as mitochondrial and ER perturbation with features of paraptosis and programmed necrosis.
RESUMO
Bone loss and endocrine dysfunction are potential late complications of allogeneic stem cell transplant (allo-SCT); however, scant information concerning the long-term effects in SCT adult patients is available. In the present study, we evaluated bone status, expressed as bone mineral density (BMD), and endocrine functions including PTH, TSH, free T4, testosterone, SHBG, FSH, LH, and IGF-1, in 20 adult leukemia patients >10 years after allo-SCT. A low BMD (Z score <-2.0) was observed in two patients; two patients had osteoporotic fractures, and two had a unilateral avascular necrosis of the femoral head. Elevated PTH was observed in 30% of patients, and 25-hydroxy vitamin D (25(OH)D) was low (<50 nmol/L) in 45% of the patients. The majority of the patients had thyroid tests within the reference range, while elevated FSH values were present in 8 of 12 males. We conclude that adult leukemia patients have relatively well-preserved BMD >10 years post-allo-SCT. Prophylactic treatment of osteoporosis should be individualized, but control of BMD is necessary for long-term follow-up. Control of PTH and vitamin D levels before and after allo-SCT is recommended, and vitamin D supplementation should be considered if indicated. Estrogen replacement therapy is a routine treatment in females, whereas gonadal function in males requires further investigation.
