Constitutive Stat3 activation in normal mucosa and tumors from
SCCHN patients. (A) Extracts (20 μg) were prepared
from representative tumors (T1–3) and normal mucosa samples (N1–3)
from SCCHN patients as well as normal mucosa biopsies from patients
without cancer (C1–3). EMSA was performed with radiolabeled hSIE
duplex oligonucleotide. The positions of the SIF-A complex (Stat3
homodimer), SIF-B complex (Stat1/Stat3 heterodimer), and SIF-C
complex (Stat1 homodimer) are indicated on the right.
(B) cumulative results of Stat3 activation levels in
control and SCCHN tissues showing increased constitutive Stat3
activation levels (SIF-A signal) in tumors (P =
0.012) and normal mucosa from SCCHN patients (P =
0.018) compared with normal mucosa from control patients without
cancer. (C) EMSA was performed by using extracts of a
representative SCCHN tumor before and after stimulation with TGF-α
(30 ng/ml for 30 min). Extracts were preincubated with rabbit
antibody to Stat1 (C-24) or Stat3 (C-20) or no antibody, as indicated.
The position of the SIF-A, -B, and -BC complexes and the supershifted
complexes are indicated on the right.