Rituximab Senzitizes B-CLL Cells with Inactived p53 to fludarabine
TRBUŠEK, Martin, Soňa ČEJKOVÁ, Jitka CHUMCHALOVÁ, Zdeněk POSPÍŠIL, Jana ŠMARDOVÁ, Petr KUGLÍK, Michael DOUBEK, Yvona BRYCHTOVÁ, Šárka POSPÍŠILOVÁ and Jiří MAYER. Rituximab Senzitizes B-CLL Cells with Inactived p53 to fludarabine. 2006. |
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Basic information | |
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Original name | Rituximab Senzitizes B-CLL Cells with Inactived p53 to fludarabine |
Name in Czech | Rituximab senzitivizuje B-CLL buňky s inaktivovaným p53 k fludarabinu |
Authors | TRBUŠEK, Martin (203 Czech Republic, guarantor), Soňa ČEJKOVÁ (203 Czech Republic), Jitka CHUMCHALOVÁ (203 Czech Republic), Zdeněk POSPÍŠIL (203 Czech Republic), Jana ŠMARDOVÁ (203 Czech Republic), Petr KUGLÍK (203 Czech Republic), Michael DOUBEK (203 Czech Republic), Yvona BRYCHTOVÁ (203 Czech Republic), Šárka POSPÍŠILOVÁ (203 Czech Republic) and Jiří MAYER (203 Czech Republic). |
Edition | 2006. |
Other information | |
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Original language | English |
Type of outcome | Conference abstract |
Field of Study | 30200 3.2 Clinical medicine |
Country of publisher | United States of America |
Confidentiality degree | is not subject to a state or trade secret |
RIV identification code | RIV/00216224:14310/06:00019160 |
Organization unit | Faculty of Science |
UT WoS | 000242440402092 |
Keywords in English | B-CLL p53 rituximab fludarabine in vitro |
Tags | Reviewed |
Changed by | Changed by: prof. RNDr. Zdeněk Pospíšil, Dr., učo 707. Changed: 1/4/2010 18:31. |
Abstract |
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Background: Defects in the p53 gene predispose B CLL patients for an inferior outcome, particularly a resistance to treatment by conventional chemotherapeutics. Very little data exist, however, about the efficacy of monoclonal antibody rituximab on B CLL cells bearing p53 abnormalities. One reason for that might be a methodological: rituximab alone does not have virtually any effect on the viability of B CLL cells when cultivated in vitro, unless an active human plasma is added. After that, however, the cells are quickly lysed by complement, what is a process independent on p53. Aims: We used an in vitro system (not containing the active human plasma) to monitor a rituximab activity on B CLL cells with p53 inactivation in relation to subsequently used nucleoside analog fludarabine, which demonstrably acts through the p53 in B CLL cells. Methods: The p53 abnormalities in blood samples of B-CLL patients were detected by FISH and by functional yeast analysis coupled to sequencing, as described previously (Trbusek et al., Leukemia 2006, 20: 1159 to 1161[Medline]). Vitally frozen samples were used in all cases, after 24h precultivation. Mononuclear cells were cultivated for 72h with or without 20ug/ml of rituximab and subsequently for another 48h with four different concentrations of fludarabine (40ug/ effect of rituximab pretreatment was determined by an ANOVA analysis, with the value p=0,05 being a threshold for a statistical significance. To monitor an apoptosis (a suppossed mechanism of fludarabine action), the Western blotting was used for the caspase3 cleavage, which was proved previously to occur in drug treated B CLL cells. Results: In the subgroup of eleven p53/wt samples the three cases manifested sensitization by rituximab for fludarabine activity, one case showed an oposite (antagonistic) effect, while there was no significant difference for another seven samples. Among ten p53mutated samples there was just one case exhibiting no influence of rituximab pretreatment (with the p53 alleles being deletion / 281 Asp:Glu), one sample manifested with antagonistic effect (del / 220 Tyr:Cys), while the remaining eight cases showed a statistically significant sensitization by rituximab (del / truncated protein aa 314, del / no protein, del/ wt protein, del / 248 Arg:Gln, del / 249 Arg:Gly, del / del aa 252, del / del aa 252 to 254, and a composed mutant 281Asp:Asn / 254 Ile:Thr). We noticed a statistically significant potentiation also in three out of four ATM deleted samples (ATM is the p53regulatory kinase). An apoptosis occured after fludarabine addition both in pretreated and control cells, as evidenced by the caspase3 cleavage in some (but not all) samples. Conclusions: We show, to our konwledge for the first time, that rituximab can significantly sensitize the B CLL cells bearing different types of p53 mutations to fludarabine. This result warrants further investigation of the mechanism behind. ml to 0,625ug/ml). The cell viability was determined by a WST1 assay. A sensitization |
Abstract (in Czech) |
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Background: Defects in the p53 gene predispose B CLL patients for an inferior outcome, particularly a resistance to treatment by conventional chemotherapeutics. Very little data exist, however, about the efficacy of monoclonal antibody rituximab on B CLL cells bearing p53 abnormalities. One reason for that might be a methodological: rituximab alone does not have virtually any effect on the viability of B CLL cells when cultivated in vitro, unless an active human plasma is added. After that, however, the cells are quickly lysed by complement, what is a process independent on p53. Aims: We used an in vitro system (not containing the active human plasma) to monitor a rituximab activity on B CLL cells with p53 inactivation in relation to subsequently used nucleoside analog fludarabine, which demonstrably acts through the p53 in B CLL cells. Methods: The p53 abnormalities in blood samples of B-CLL patients were detected by FISH and by functional yeast analysis coupled to sequencing, as described previously (Trbusek et al., Leukemia 2006, 20: 1159 to 1161[Medline]). Vitally frozen samples were used in all cases, after 24h precultivation. Mononuclear cells were cultivated for 72h with or without 20ug/ml of rituximab and subsequently for another 48h with four different concentrations of fludarabine (40ug/ effect of rituximab pretreatment was determined by an ANOVA analysis, with the value p=0,05 being a threshold for a statistical significance. To monitor an apoptosis (a suppossed mechanism of fludarabine action), the Western blotting was used for the caspase3 cleavage, which was proved previously to occur in drug treated B CLL cells. Results: In the subgroup of eleven p53/wt samples the three cases manifested sensitization by rituximab for fludarabine activity, one case showed an oposite (antagonistic) effect, while there was no significant difference for another seven samples. Among ten p53mutated samples there was just one case exhibiting no influence of rituximab pretreatment (with the p53 alleles being deletion / 281 Asp:Glu), one sample manifested with antagonistic effect (del / 220 Tyr:Cys), while the remaining eight cases showed a statistically significant sensitization by rituximab (del / truncated protein aa 314, del / no protein, del/ wt protein, del / 248 Arg:Gln, del / 249 Arg:Gly, del / del aa 252, del / del aa 252 to 254, and a composed mutant 281Asp:Asn / 254 Ile:Thr). We noticed a statistically significant potentiation also in three out of four ATM deleted samples (ATM is the p53regulatory kinase). An apoptosis occured after fludarabine addition both in pretreated and control cells, as evidenced by the caspase3 cleavage in some (but not all) samples. Conclusions: We show, to our konwledge for the first time, that rituximab can significantly sensitize the B CLL cells bearing different types of p53 mutations to fludarabine. This result warrants further investigation of the mechanism behind. ml to 0,625ug/ml). The cell viability was determined by a WST1 assay. A sensitization |
Links | |
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LC06024, research and development project | Name: Centrum Jaroslava Hájka pro teoretickou a aplikovanou statistiku |
Investor: Ministry of Education, Youth and Sports of the CR, Jaroslav Hájek Center for Theoretical and Applied Statistics | |
NR8445, research and development project | Name: In vitro sensitivita/resistence CLL buněk s inaktivovaným p53 na moderní léčbu |
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