
356 Yang et al.
Investigación Clínica 63(4): 2022
this adjustment takes place especially at two
points with extraordinary intensity and care.
The cell, first, decides to replicate its own
DNA, and second, to initiate mitotic divi-
sion. These steps are in the realm of passing
from G1 to S and from G1 to M.
The cells in each group were successi-
vely inoculated into a 96-well culture plate,
and the cell density was adjusted to 10×10
4
/
mL. The cells were observed for 5h, and the
corresponding intervention was given to
each group. Cultured again for 36 h, the
MTT assay was used to observe the situation
of each group of cells, and the proliferation
of each group was plotted. The experiment
was repeated 3 times.
Flow cytometry detection
Colorectal cancer HCT116 cells with
a concentration of 2×10
8
/L were inocula-
ted into 6-well culture plates for 12 h. The
control group was given routine culture, and
the curcumin low-dose, medium-dose and
high-dose groups were given 20, 40 and 80
μmol/L curcumin for intervention. After 48
h of intervention, the cells were collected
and centrifuged at 1000 rpm for 10 min.
The cells were washed with PBS twice, and
1ml of precooled 70% ethanol was used for
beating and dispersing. The cells were fixed
overnight at -20°C, and then mixed with 0.8
μg/mL. The cells were incubated at room
temperature for 30 min without light.
Western blot assay
Western blot analysis was performed
essentially according to standard protocol.
Briefly, the cells were solubilized in lysis
buffer (50 mM Tris, 100 mM NaCl, 2.5 mM
EDTA, 1% Triton X-100, 1% Nonidet P-40, 2.5
mM Na3O4V, 25 μg/mL aprotinin, 25 μg/mL
leupeptin, 25 μg/mL pepstatin A, and 1 mM
phenylmethylsulfonyl fluoride). After clarifi-
cation at 10,000g for 15 minutes, the super-
natant was used for Western blot analysis. In
all analyses, protein concentration, determi-
ned by the Bio-Rad Protein Assay kit (Bio-
Rad, Hercules, CA), was standardized among
the samples. Aliquots of cell lysates con-
taining 50 μg of protein were separated by
sodium dodecyl sulfate–polyacrylamide gel
electrophoresis. After electrophoresis, pro-
teins were transferred electrophoretically
onto supported nitrocellulose membranes
(Osmonics, Gloucester, MA). Membranes
were incubated for 1 hour at room tempe-
rature with blocking buffer, TBS-T (20 mM
Tris, pH7.6, 100 μMNaCl, 0.1% Tween-20)
and 5% nonfat dry milk with gentle agita-
tion. After washing the membranes with
TBS-T, they were incubated overnight at 4°C
in TBS-T buffer containing antibody dilution
buffer as suggested by the manufacturer and
with antibodies (1:1000 dilution) to CD44,
CD166 (Santa Cruz Biotechnology, Santa
Cruz, CA), or epidermal growth factor re-
ceptor (EGFR; Cell Signaling, Beverly, MA).
The membranes were washed three times
with TBS-T and subsequently incubated with
appropriate secondary antibodies (1:5000
dilutions) in TBS-T containing 5% milk for
1 to 2 hours at room temperature with gent-
le agitation. The membranes were washed
again with TBS-T, and the protein bands were
visualized by enhanced chemiluminescence
(ECL) detection system (Amersham, Pisca-
taway, NJ). The membranes containing the
electrophoresed proteins were exposed to
X-Omat film (Sigma-Aldrich, St Louis, MO).
The membranes were stripped (twice × for
15 minutes at 55°C) in stripping buffer con-
taining 100 mM 2-mercaptoethanol, 2% so-
dium dodecyl sulfate, and 62.5 mM Tris-HCl
pH 6.7, and reprobed for β-actin using the
corresponding antibodies, which were used
as a loading control. All Western blots were
performed at least three times for each expe-
riment
8
. The method used to identify prote-
ins in the membrane is the blotting method.
In this technique, protein bands are transfe-
rred from the gel to a nitrocellulose mem-
brane that can bind and stabilize proteins.
To do this, by blotting, the protein molecules
were removed from the gel and placed in the
same position on the surface of the membra-
ne, so we could easily study them, separate