formazans and Leukemia--Myeloid

We have found the short-term MTT assay to be a simple, reproducible chemosensitivity technique, suitable for use throughout the time course of disease. We now have 12 years' experience of using this method in a variety of tumour types, both haematological and solid malignancies. Tumour cells are isolated from bone marrow, malignant effusions or solid biopsies and subjected to drug exposure for 48-96 h. Cell survival is measured by re-incubation in MTT for 4 h. We have found a significant correlation of in vitro results with in vivo outcome for acute myeloid leukaemia (AML) and for ovarian cancer (both p < 0.0001) with an assay sensitivity of 98% for AML and 81% for ovarian cancer. Furthermore, the 5-year survival of ovarian cancer patients treated with a drug found sensitive in vitro is significantly higher than that for patients treated with a drug found resistant in vitro (p = 0.033). We have correlated assay results with drug resistance markers. For example, expression of the newly described half transporter BCRP is related to daunorubicin resistance (p < 0.05). The MTT assay is also suitable for screening for modulation of drug resistance. We have found that the DNA polymerase inhibitor aphidicolin markedly increases in vitro sensitivity to the platinum drugs in ovarian cancer and cytosine arabinoside in AML in the majority of patients. The greatest effect was seen for patients deemed resistant in vitro to these agents. We have identified novel drug combinations which demonstrate significant synergism using this methodology and have also used it to study the emergence of drug resistance in cell line models with a view to its prevention. In conclusion, we have found the MTT assay to be a simple, repeatable, adaptable technique which produces accurate information to help the clinician select suitable treatment for individual cases.

Topics: Acute Disease; Antineoplastic Agents; Biomarkers, Tumor; Cell Division; Cell Survival; Drug Resistance, Multiple; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Female; Formazans; Humans; Leukemia, Myeloid; Ovarian Neoplasms; Tetrazolium Salts

Arsenic trioxide (As(2)O(3)) has recently been shown to be effective to inhibit the growth and to induce apoptosis in acute promyelocytic leukemia (APL) but not in acute myeloid leukemia (AML) cells. Recently, we have isolated an As(2)O(3) sensitive subclone JCS-16 from the murine myeloid leukemia WEHI 3B (JCS). At the concentrations of 0.3-3 microM, As(2)O(3) induces a dose-dependent cytotoxicity and growth inhibition on the JCS-16 cells. As(2)O(3) also induces apoptotic cell death, as judged by the presence of apoptotic nuclei, at 6 h after treatment. Morphological differentiation was not observed in As(2)O(3) treated JCS cells. Neutralizing anti-TNF-alpha antibody was found to reduce the As(2)O(3)-mediated apoptotic cell death of JCS-16 cells. Growth inhibitory effect of As(2)O(3) was also reduced after the addition of anti-TNF-alpha. In addition, reverse transcription polymerase chain reaction (RT-PCR) and reverse northern blot analysis demonstrated that the expression of TNF receptor (TNF-R2), IL-4, and IL-4R was down-regulate at 1 h after As(2)O(3) treatment. The expression of TNF-alpha and TNF-R1 was not affected. Our results suggest that the autocrine action of TNF-alpha might play a role in As(2)O(3)-induced apoptotic cell death of JCS-16 leukemia cells.

Topics: Animals; Apoptosis; Arsenic Trioxide; Arsenicals; Blotting, Northern; Cell Division; Formazans; Interleukin-4; Leukemia, Myeloid; Mice; Oxides; Receptors, Interleukin-4; Receptors, Tumor Necrosis Factor; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Tetrazolium Salts; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha