Single Amino Acid Variant Profiles of Subpopulations in the MCF‑7 Breast Cancer Cell Line

Cancers
are initiated and developed from a small population of
stem-like cells termed cancer stem cells (CSCs). There is heterogeneity
among this CSC population that leads to multiple subpopulations with
their own distinct biological features and protein expression. The
protein expression and function may be impacted by amino acid variants
that can occur largely due to single nucleotide changes. We have thus
performed proteomic analysis of breast CSC subpopulations by mass
spectrometry to study the presence of single amino acid variants (SAAVs)
and their relation to breast cancer. We have used CSC markers to isolate
pure breast CSC subpopulation fractions (ALDH+ and CD44+/CD24–
cell populations) and the mature luminal cells (CD49f–EpCAM+)
from the MCF-7 breast cancer cell line. By searching the Swiss-CanSAAVs
database, 374 unique SAAVs were identified in total, where 27 are
cancer-related SAAVs. 135 unique SAAVs were found in the CSC population
compared with the mature luminal cells. The distribution of SAAVs
detected in MCF-7 cells was compared with those predicted from the
Swiss-CanSAAVs database, where we found distinct differences in the
numbers of SAAVs detected relative to that expected from the Swiss-CanSAAVs
database for several of the amino acids.