<p class="first" id="d505954e164">Uterine fibroids (UFs) are clonal, hormonally regulated,
benign smooth-muscle myometrial
tumors that severely affect female reproductive health, although their unknown etiology
limits effective care. UFs occur fourfold more commonly in African American women
than in Caucasian women, and African American women generally have earlier disease
onset and greater UF tumor burden, although the mechanism of this ethnic disparity
has not been identified. Recent findings have linked cancer (ie, tumor) risk to increased
tissue-specific stem cell division and self-renewal and suggest that somatic mutations
in myometrial stem cells (MyoSCs) convert them into tumor-initiating cells, leading
to UF. Specifically, preliminary results in paraffin-embedded myometrial tissues have
shown increased STRO-1
<sup>+</sup>/CD44
<sup>+</sup> MyoSCs in African American versus Caucasian women. Using specific methods
of flow
cytometry and automated quantitative pathology imaging, a large cohort of myometrial
samples were investigated to determine how the STRO-1
<sup>+</sup>/CD44
<sup>+</sup> MyoSCs change with regard to a patient's race, age, parity, fibroid and
hormone statuses,
and the location of UFs within the uterus. We confirmed that the STRO-1
<sup>+</sup>/CD44
<sup>+</sup> MyoSC population is expanded in African American women, is correlated
with parity
and fibroid number, and fluctuates with cyclic menstrual cycle hormone changes and
age. Our data suggest that an expanded MyoSC population increases the formation of
tumor-initiating cells, ultimately contributing to increased UF prevalence and burden
in African American women.
</p>