Abstract
Recently published articles have reported the controversial data regarding expression
of aldehyde dehydrogenase isozyme 1A1 (ALDH1A1), a potential candidate marker for
normal and cancer stem cells (CSCs), in thyroid tissues. These data prompted us to
re-evaluate expression of ALDH1A1 in normal and cancerous thyroid tissues by 2 different
means. The first method was immunohistochemistry with 2 different anti-ALDH1A1 antibodies
from distinct companies. Following validating the integrity of these 2 antibodies
by Western blotting with ALDH-expressing and nonexpressing cancer cell lines and immunohistochemistry
with breast and colon tissues, we report here significant and comparable expression
of ALDH1A1 in both normal and cancerous thyroid tissues with both antibodies. Next,
relative expression levels of ALDH isozymes were evaluated by reverse transcription-polymerase
chain reaction (RT-PCR), revealing that ALDH1A1 was the most highly expressed isozyme
followed by ALDH9A1 and relative expression patterns of isozymes were very similar
in normal and cancerous tissues. All these data demonstrate that thyroid cells of
normal and cancer origins do express ALDH1A1 and to a lesser extent 9A1. Further study
will be necessary to study functional significance of ALDH1A1 in the function and
behaviors of thyroid normal and cancer stem cells.
Key words
stem cells - immunohistochemistry - thyroid cancer
