Mutations or deletions in TP53 or ATM are well-known determinants of poor prognosis in chronic lymphocytic leukemia (CLL), but only account for approximately 40% of chemo-resistant patients. Genome-wide sequencing has uncovered novel mutations in the splicing factor sf3b1, that were in part associated with ATM aberrations, suggesting functional synergy. We first performed detailed genetic analyses in a CLL cohort (n=110) containing ATM, SF3B1 and TP53 gene defects. Next, we applied a newly developed multiplex assay for p53/ATM target gene induction and measured apoptotic responses to DNA damage. Interestingly, SF3B1 mutated samples without concurrent ATM and TP53 aberrations (sole SF3B1) displayed partially defective ATM/p53 transcriptional and apoptotic responses to various DNA-damaging regimens. In contrast, NOTCH1 or K/N-RAS mutated CLL displayed normal responses in p53/ATM target gene induction and apoptosis. In sole SF3B1 mutated cases, ATM kinase function remained intact, and γH2AX formation, a marker for DNA damage, was increased at baseline and upon irradiation. Our data demonstrate that single mutations in sf3b1 are associated with increased DNA damage and/or an aberrant response to DNA damage. Together, our observations may offer an explanation for the poor prognosis associated with SF3B1 mutations.

• MeSH
• apoptóza MeSH
• ATM protein metabolismus   MeSH
• chronická lymfatická leukemie genetika   MeSH
• delece genu MeSH
• doxorubicin farmakologie   MeSH
• fosfoproteiny genetika   MeSH
• genom lidský MeSH
• histony metabolismus   MeSH
• imidazoly farmakologie   MeSH
• kohortové studie MeSH
• lidé MeSH
• malý jaderný ribonukleoprotein U2 genetika   MeSH
• mutace * MeSH
• mutační analýza DNA MeSH
• nádorový supresorový protein p53 genetika   MeSH
• piperaziny farmakologie   MeSH
• poškození DNA MeSH
• prognóza MeSH
• průtoková cytometrie MeSH
• receptor Notch1 genetika   MeSH
• regulace genové exprese u leukemie * MeSH
• vidarabin analogy a deriváty   farmakologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The ATM-p53 DNA-damage response (DDR) pathway has a crucial role in chemoresistance in CLL, as indicated by the adverse prognostic impact of genetic aberrations of TP53 and ATM. Identifying and distinguishing TP53 and ATM functional defects has become relevant as epigenetic and posttranscriptional dysregulation of the ATM/p53 axis is increasingly being recognized as the underlying cause of chemoresistance. Also, specific treatments sensitizing TP53- or ATM-deficient CLL cells are emerging. We therefore developed a new ATM-p53 functional assay with the aim to (i) identify and (ii) distinguish abnormalities of TP53 versus ATM and (iii) enable the identification of additional defects in the ATM-p53 pathway. Reversed transcriptase multiplex ligation-dependent probe amplification (RT-MLPA) was used to measure ATM and/or p53-dependent genes at the RNA level following DNA damage using irradiation. Here, we showed that this assay is able to identify and distinguish three subgroups of CLL tumors (i.e., TP53-defective, ATM-defective and WT) and is also able to detect additional samples with a defective DDR, without molecular aberrations in TP53 and/or ATM. These findings make the ATM-p53 RT-MLPA functional assay a promising prognostic tool for predicting treatment responses in CLL.

• MeSH
• antitumorózní látky farmakologie   MeSH
• ATM protein genetika   metabolismus   MeSH
• biotest MeSH
• chemorezistence genetika   MeSH
• chronická lymfatická leukemie farmakoterapie   genetika   metabolismus   patologie   MeSH
• doxorubicin farmakologie   MeSH
• epigeneze genetická MeSH
• lidé MeSH
• multiplexová polymerázová řetězová reakce metody   MeSH
• mutace * MeSH
• nádorový supresorový protein p53 genetika   metabolismus   MeSH
• polymerázová řetězová reakce s reverzní transkripcí metody   MeSH
• poškození DNA MeSH
• regulace genové exprese u leukemie * MeSH
• RNA nádorová genetika   MeSH
• senzitivita a specificita MeSH
• vidarabin analogy a deriváty   farmakologie   MeSH
• záření gama MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH