An article published this year in “FRONTIERS IN ONCOLOGY” using our Annexin
V–fluorescein isothiocyanate/propidium iodide (Annexin V-FITC/PI) double
staining and our PI/RNase
staining solution, by our customers from Cancer Research Center-IBMCC
(USAL-CSIC), Institute of Biomedical Research of Salamanca (IBSAL), Hematology
Department, University Hospital of Salamanca, Salamanca, Spain, in the analysis
of Targeting Ongoing DNA Damage in Multiple Myeloma: effects of DNA Damage
response inhibitors on Plasma cell survival. Congrats and Thanks.
Summary:
Human myeloma cell lines (HMCLs)
and a subset of myeloma patients with poor prognosis exhibit high levels of
replication stress (RS), leading to DNA damage. In this study, we confirmed the
presence of DNA double-strand breaks (DSBs) in several HMCLs by measuring γH2AX and RAD51 foci and analyzed the effect of various inhibitors of the
DNA damage response on MM cell survival. Inhibition of ataxia telangiectasia
and Rad3-related protein (ATR), the main kinase mediating the response to RS,
using the specific inhibitor VE-821 induced more cell death in HMCLs than in
control lymphoblastoid cells and U266, an HMCL with a low level of DNA damage.
The absence of ATR was partially compensated by ataxia telangiectasia-mutated
protein (ATM), since chemical inhibition of both kinases using VE-821 and
KU-55933 significantly increased the death of MM cells with DNA damage. We
found that ATM and ATR are involved in DSB repair by homologous recombination
(HR) in MM. Inhibition of both kinases resulted in a stronger inhibition that
may underlie cell death induction, since abolition of HR using two different
inhibitors severely reduced survival of HMCLs that exhibit DNA damage. On the
other hand, inhibition of the other route involved in DSB repair, nonhomologous
end joining (NHEJ), using the DNA-PK inhibitor NU7441, did not affect MM cell
viability. Interestingly, we found that NHEJ inhibition did not increase cell
death when HR was simultaneously inhibited with the RAD51 inhibitor B02, but it
clearly increased the level of cell death when HR was inhibited with the MRE11
inhibitor mirin, which interferes with recombination before DNA resection takes
place. Taken together, our results demonstrate for the first time that MM cells
with ongoing DNA damage rely on an intact HR pathway, which thereby suggests
therapeutic opportunities. We also show that inhibition of HR after the initial
step of end resection might be more appropriate for inducing MM cell death,
since it prevents the occurrence of a compensatory NHEJ repair mechanism. These
preclinical observations provide the rationale for its clinical evaluation.
Reference:
Product link:
FITC Annexin V Apoptosis Detection Kit with PI: http://www.immunostep.com/apoptosis-tools/3727-anxvkf-100t.html
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