Importance of Stem Cell Biology
Stem cells are undifferentiated cells that can differentiate into specialized cells which include
embryonic stem, adult stem cells, and induced pluripotent stem cells. Embryonic stem cells are
pluripotent, which means they can develop into any specialized cell in the body. Adult stem cells exist in
certain tissues that help with regenerative functions, while iPSCs are stem cells that genetically
programmed to behave like embryonic stem cells. Being able to control their gene expression and
identify and discriminate these cells from the surrounding cells can be crucially beneficial to future
medicinal research. The first study was based on how Numb family proteins affect radiosensitivity of
non-small cell lung cancer cells. Numb is reported to function as a component of the adherens junction
to regulate cell adhesion and migration and to get involved in the ubiquitylation of p53 (Trp53) and Gli1
to regulate cancer initiation. The second study is using cell markers to differentiate between
mesenchymal stem cells and non-mesenchymal stem cells. The third study test and correlates the
Sox21a protein with its role regarding intestinal regeneration and tumorigenesis.
Numb family proteins are known to be involved in differentiation and specification of CSCs and
have multiple roles in disease conditions. CSCs recognized as tumorigenic cells that have the ability of
differentiating and self-renewing and that are resistant to conventional therapy, including
chemotherapy and radiation therapy. Proteins and radioresistance-related factors as therapeutic targets
are not fully understood, this study by Shan was done to see how the Numb gene affected radiation
sensitivity (1).
To show this correlation, Human lung adenocarcinoma A549 cell line was obtained and then
sorted and stained through flow cytometry. Eukaryotic expression plasmid pcDNA3.1 was used to
construct shRNA-Numb and pcDNA-Numb. Vacant pcDNA3.1, over-expressed pcDNANumb, and gene
knockout shRNA-Numb were transfected with A549-SP cells in the logarithmic growth phase,
respectively; then, the cells were grouped into pcDNA3.1 group, pcDNA-Numb group and shRNA-Numb
group (1).
Numb expression was determined using real-time quantitative PCR and a Western Blot. mRNA
expression was .25% for the knockdown group which was considerably less than the pcDNA3.1 group
which was .75% and pcDNA-Numb group which had a mRNA expression of 1.25%. These results were
similar in protein expression as the knockout had the lowest protein expression, while the pcDNA3.1
group, pcDNA-Numb group had considerably more protein being expressed (1).
For proliferation activity, MTT method was used to measure the change of the NSCLC stem cells
both before and after irradiation with different doses of 60Coc ray. To detect the apoptosis of the NSCLC
stem cells Hoechst staining and Annexin V-FITC/PI was used. To determine the effect of Numb
