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Ibrahim et al ALDHs and prostate cancer

CONCLUDING REMARKS DECLARATIONS

The number of papers that report ALDH expression Acknowledgments
in the context of cancer is largely attributable to the We wish to acknowledge Prostate Cancer UK (RIA15-
use of the Aldefluor assay as a means to identify and ST2-022 & PhD grant S12-027) for financial support
isolate subpopulations with particularly stemness and sponsorship, and Yaqeen Sawalha for producing
characteristics. However, selected ALDH isoforms figures for this manuscript.
are also emerging as critical players in chemo-
and radioresistance and a signature of tumour Author’s contributions
aggressiveness in conjunction with cells capable Manuscript writting and revision: Ibrahim AIM, Sadiq
of migration, invasion and metastasis. Still, as is
clear from this review of ALDH expression and M, Frame FM, Maitland NJ, Pors K
function in PCa and other recent reviews [45,46,87,222] ,
the ever increasing number of publications that Availability of data and materials
reveal inconsistent and sometimes contradictory Not applicable.
information is not helpful in clarifying ALDHs as
potential biomarkers of specific cancer types or CSC Financial support and sponsorship
population; e.g., many early studies that reported on None.
ALDHs, utilised antibodies that only stained for e.g.
ALDH1 but were not selective for 1A1, 1A2, 1A3, Conflicts of interest
1B1, 1L1 or 1L2. Equally the Aldefluor assay is not The authors declare there are no conflicts of interest.
isoform-selective and has contributed to inefficient
validation of these enzymes. Furthermore, previous Ethical approval and consent to participate
studies were carried out when the understanding of Not applicable.
cancer cell subtypes, and the involvement of TME
was limited, resulting in incomplete ALDH profiling. Consent for publication
Bearing this in mind, currently emerging evidence in Not applicable.
PCa suggests the dominant isoforms are ALDH1A1,
1A2, 1A3, 3A1 and 7A1. The expression and Copyright
function have been demonstrated using a number © The Author(s) 2018.
of different 2D and 3D cancer models as well as
clinical samples. Further investigations of these
isoforms are required in order to fully validate their REFERENCES
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10 Journal of Cancer Metastasis and Treatment ¦ Volume 4 ¦ Aug 21, 2018