Int J Oncol 49: [Related article:] 753-762, 2016; DOI:
10.3892/ijo.2016.3558
Subsequently to the publication of the above article,
an interested reader drew to the authors' attention that,
concerning the three breast cancer cell lines investigated in their
study, it was surprising that they should have detected caspase-3
expression in the MCF-7 cell line, as reported for example in Fig.
6, since it has been shown that MCF-7 cells do not express
caspase-3 (see the paper by Reiner U. Jänicke and colleagues
entitled 'MCF-7 breast carcinoma cells do not express caspase-3'.
Breast Cancer Res Treat vol. 117.1 (2009); p. 219-221).
In their response, the authors acknowledge that the
prevailing consensus in the literature, established by the seminal
work of Jänicke et al in an article they published in 1998
in Journal of Biological Chemistry holds that MCF-7 cells
harbor a 47-bp deletion in exon 3 of the CASP3 gene, resulting in a
frameshift mutation and a premature stop codon, with consequent
absence of detectable functional protein. The authors' own article
acknowledged this controversy by citing conflicting reports
(references 13 and 39 compared with references 41-43); however,
they also recognize in retrospect that this should have prompted a
more circumspect interpretation of their own data. Following a
critical re-evaluation of their methodology, the authors wish to
draw attention to the following limitations of the present
work:
The band detected in MCF-7 cells using antibody H-277
cannot be unambiguously attributed to caspase-3, and
cross-reactivity with co-expressed proteins of similar molecular
weight, most notably caspase-7, cannot be excluded.
The DDRT-PCR amplicon obtained from MCF-7 cells with
the reported primers may correspond to the aberrant CASP3
transcript arising from the exon 3 deletion, and does not
necessarily represent a translation-competent mRNA. Sequencing of
this amplicon was not performed, and would be required to resolve
this question.
The conclusions of the article on caspase-3
expression in MCF-7 cells should therefore be read with these
methodological caveats in mind. Importantly, these limitations do
not affect the principal findings of the study concerning
MDA-MB-231 and MCF-10F cell lines, for which the experimental
evidence remains methodologically sound.
The authors are grateful to the Editorial Board of
International Journal of Oncology for the rigor of the
review process, and also for the opportunity to address these
concerns transparently. They also thank the reader of the article
for drawing these concerns to their attention.
