Changes in leukemic cell nuclei revealed by differential scanning calorimetry

Abstract

Using differential scanning calorimetry we analyzed the thermal profiles of nuclei from normal and B-cell chronic lymphocytic leukemia mononuclear cells. Intact nuclear fraction of normal mononuclear cells is characterized by four thermal transitions, i.e., at 60, 70, 83 and 103 degrees C. Leukemic nuclear samples revealed the transitions at 67 and 83 degrees C, however, in more aggressive stage of the disease additional thermal peaks at 76 and 93 degrees C were observed. Our very preliminary results revealed that mononuclear cell nuclear fraction from blood of patients responding to the used therapy, i.e., cladribine alone or its combination with mitoxantrone and cyclophosphamide indicates decrease (or even loss) of transition at 93 degrees C concomitant with increase of transition at 76 degrees C. A complementary study showed that in mononuclear cells of patients who appeared to be sensitive to chemotherapy the decrease of antiapoptotic Bcl-2 protein expression and signs of apoptotic morphology were observed.

Relationship between in vitro drug sensitivity and clinical response of patients to treatment in chronic lymphocytic leukemia

“…as described, a significant decrease or even complete loss of thermal transition at 95±3˚C was observed in DsC scans of nuclear preparations when therapy was effective (22,24). Moreover, our results reveal that a comparison of the DSc profiles of nuclear preparations with the results of cell viability, apoptosis rate, and proteolytic degradation of the ParP-1 display a good predictive value for cll cell sensitivity to anticancer drugs.…”

“…it has been reported by our laboratory that an additional thermal transition occurs at 95±5˚C in the DsC profiles of nuclear fraction preparations obtained from the mononuclear cells of patients in an advanced stage of cll, along with the main transition at 83±3˚C characteristic for healthy donors (22,23). Moreover, the obtained results also revealed that the decrease (or even loss) of thermal transition at 95±5˚C in thermal scans of nuclear preparations of cll cells, after both in vivo and in vitro drug administration, are attributable to chromatin fragmentation during apoptosis (23,24).…”

“…Both, the pelleted control and drug-treated cll cell samples were rinsed with cold PBs and then suspended in isotonic sucrose solution containing 5 mM Mgcl 2 , 0.5% triton X-100, 50 mM tris-HCl (pH 7.4) and protease inhibitors as previously described (22). cell samples were homogenized in a Potter homogenizer, and centrifuged at 800 x g for 8 min resulting in a crude nuclear pellet.…”

Toward personalized therapy for chronic lymphocytic leukemia

“…However, we have observed a low expression of Noxa before drug exposure of patient RJ's cells and its lack after cell exposure to RCM. As previously identified, 24 the appearance of additional thermal transition at about 95 ± 5°C zone in cell nuclei obtained from PBMC samples from patients' blood could be proposed as a new parameter for the advanced stage of CLL. Interestingly, the decrease of this transition appears to have a prognostic significance and could reflect patients' potential sensitivity to the treatment in vivo.…”

“…Accordingly, in PBMCs from blood of patients who achieved CR to RCC therapy, a strong decline in thermal transition at 95 ± 5°C, accompanied by the increase of main transition at about 83 ± 3°C, was observed. 24 The differences in thermal scans of nuclear fraction from drug-treated CLL cell samples seems to be a consequence of chromatin remodeling during the apoptosis process.…”