Inhibition of RNA transcription: a biochemical mechanism of action against chronic lymphocytic leukemia cells by fludarabine

Huang, Peng; Sandoval, Alex; Neste, Éric Van Den; Keating, Michael J.; Plunkett, William

doi:10.1038/sj.leu.2401845

Cited by 76 publications

(69 citation statements)

References 27 publications

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“…It was hypothesized that blocking the background DNA repair might activate the p53 pathway in CLL cells. 21 This is consistent with resistance of del17p13 CLL cells to fludarabine and the strong induction of p21 and PUMA mRNA observed in this study. Moreover, we observed that a-amanitin can induce apoptosis in CLL cells irrespective of p53 status similar to actinomycin D, suggesting that the p53-dependent component in fludarabine induced apoptosis is not caused by transcriptional repression (Supplementary Figure 10).…”

Section: Discussionsupporting

confidence: 91%

“…19,20 In CLL, it has been compared with fludarabine as a general inhibitor of RNA synthesis; however, its differential effect on individual mRNAs has not been analyzed. 21 In this study, we demonstrate that actinomycin D induced apoptosis in CLL is independent of del17p status. On the basis of transcriptome profiling, protein quantification and intracellularstaining using fluorescence-activated cell sorting, we find that in CLL cells actinomycin D targets both survival proteins MCL1 and BCL2.…”

Section: Introductionmentioning

confidence: 49%

“…21 The degree of apoptosis induction of fludarabine and a-amanitin was directly correlated to reduction of H]uridine incorporation, suggesting that the inhibition of RNA synthesis, rather than DNA synthesis is an important mechanism of fludarabine toxicity. However, it was also noted that fludarabine, when reducing RNA synthesis to the same degree as actinomycin D, had a much stronger apoptosis-inducing effect, thereby implicating additional mechanisms of cell death induction.…”

Section: Discussionmentioning

confidence: 94%

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Actinomycin D induces p53-independent cell death and prolongs survival in high-risk chronic lymphocytic leukemia

et al. 2012

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Chronic lymphocytic leukemia (CLL) is the most prevalent lymphoid malignancy in the elderly of the Western world. Although treatment options have improved over the past two decades, 10-15% of patients still have a poor prognosis and are often resistant to therapy. Aberrations in the p53 pathway, such as a deleted (del17p13) or mutated p53 gene, are highly enriched in this class of patients. In an extensive screen for p53-independent apoptosis inducers, actinomycin D was identified from 1496 substances and shown to induce apoptosis in primary CLL cells derived from high-risk patients including those with aberrant p53, revealing a novel p53-independent mechanism of action. Both pro-survival genes BCL2 and MCL1 are targeted by actinomycin D, in contrast to fludarabine the backbone of current treatment schedules. In the well-established TCL1 transgenic mouse model for high-risk CLL, actinomycin D treatment was more effective in reducing tumor load than fludarabine, with no evidence of resistance after three treatment cycles and an overall survival increase of over 300%. Tumor load reduction was coupled to BCL2 downregulation. Our results identify the clinically approved compound actinomycin D as a potentially valuable treatment option for CLL high-risk patients.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 49%

Section: Discussionmentioning

confidence: 94%

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Actinomycin D induces p53-independent cell death and prolongs survival in high-risk chronic lymphocytic leukemia

et al. 2012

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“…Patient demographic information and relevant clinical parameters are listed in Table S1 (available on the Blood website; see the Supplemental Materials link at the top of the online article). CLL cells were isolated from blood samples by density gradient centrifugation 19 and incubated in RPMI 1640 medium supplemented with 10% FBS and penicillin (100 U/mL) ϩ streptomycin (100 g/mL) overnight before drug incubations were started. Normal lymphocytes were isolated from blood samples of 12 healthy donors using similar procedures.…”

Section: Isolation Of Cll Cells and Normal Lymphocytesmentioning

confidence: 99%

Effective elimination of fludarabine-resistant CLL cells by PEITC through a redox-mediated mechanism

Trachootham

Zhang

et al. 2008

Blood

180

179

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Chronic lymphocytic leukemia (CLL) is the most common adult leukemia, and resistance to fludarabine-based therapies is a major challenge in CLL treatment. Because CLL cells are known to have elevated levels of reactive oxygen species (ROS), we aimed to test a novel ROS-mediated strategy to eliminate fludarabine-resistant CLL cells based on this redox alteration. Using primary CLL cells and normal lymphocytes from patients (n ‫؍‬ 58) and healthy subjects (n ‫؍‬ 12), we showed that both fludarabineresistant and -sensitive CLL cells were highly sensitive to ␤-phenylethyl isothiocyanate (PEITC) with mean IC 50 values of 5.4 M and 5.1 M, respectively. Normal lymphocytes were significantly less sensitive to PEITC (IC 50 ‫؍‬ 27 M, P < .001). CLL cells exhibited intrinsically higher ROS level and lower cellular glutathione, which were shown to be the critical determinants of CLL sensitivity to PEITC. Exposure of CLL cells to PEITC induced severe glutathione depletion, ROS accumulation, and oxidation of mitochondrial cardiolipin leading to massive cell death. Such ROS stress also caused deglutathionylation of MCL1, followed by a rapid degradation of this cell survival molecule. Our study demonstrated that the natural compound PEITC is effective in eliminating fludarabine-resistant CLL cells through a redox-mediated mechanism with low toxicity to normal lymphocytes, and warrants further clinical evaluation.

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“…We are currently investigating the role of adenosine and deoxyadenosine analogues on RNA-directed mechanisms [5][6][7][8]. Our rationale for studying RNA-related processes stems from previous findings that related adenosine analogues under investigation in our laboratory inhibit polyadenylation.…”

Section: Introductionmentioning

confidence: 99%

Polyadenylation inhibition by the triphosphates of deoxyadenosine analogues

2008

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The nucleotide substrate specificity of yeast poly(A) polymerase (yPAP) was examined with various ATP analogues of clinical relevance. The triphosphate derivatives of cladribine (2-CldATP), clofarabine (Cl-F-ara-ATP), fludarabine (F-ara-ATP), and related derivatives were incubated with yPAP and 32 P-radiolabeled RNA oligonucleotide primers in the absence of ATP to assay polyadenylation. While 2-Cl-ATP resulted in primer elongation, ara-ATP and F-ara-ATP were poor substrates for yPAP. In contrast, the triphosphate derivatives of cladribine (2-Cl-dATP), clofarabine (Cl-F-ara-ATP) and its corresponding deoxyribose derivative (Cl-F-dATP) were substrates and caused chain termination in the absence of ATP. We further investigated whether analog incorporation at the 3′-terminus of RNA primers negatively impacts polyadenylation with ATP by generating RNA oligonucleotides containing either a terminal clofarabine, Cl-F-dAdo, or cladribine residue. Incorporation of any of these analogs blocks the ability of yPAP to extend RNA past the analog site, impeding the addition of a poly(A)-tail. To determine whether modified ATP analogues exhibit a concentration dependent effect on polyadenylation, poly(A)-tail synthesis by yPAP with modified ATP analogues in combination with a constant level of ATP was also examined. With all the ATP analogues assayed in these studies, there was a significant reduction in poly(A)-tail length with increasing amounts of analog triphosphate. Taken together, our results suggest that polyadenylation inhibition may be a component in the mechanism of action of adenosine analogues.

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Inhibition of RNA transcription: a biochemical mechanism of action against chronic lymphocytic leukemia cells by fludarabine

Cited by 76 publications

References 27 publications

Actinomycin D induces p53-independent cell death and prolongs survival in high-risk chronic lymphocytic leukemia

Actinomycin D induces p53-independent cell death and prolongs survival in high-risk chronic lymphocytic leukemia

Effective elimination of fludarabine-resistant CLL cells by PEITC through a redox-mediated mechanism

Polyadenylation inhibition by the triphosphates of deoxyadenosine analogues

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