Cellular redox changes have emerged as a pivotal and proximal event in
cancer.
PKI 166 is used to determine the effects of redox sensitive inhibition of EGFR,
metastasis and apoptosis in
epidermoid carcinoma. Cytotoxicity study of
PKI 166 (IC50 1.0 microM) treated A431 cells were performed by MTT assay for 48 and 72 hrs. Morphological analysis of
PKI 166 treated A431 cells for 48 hrs. revealed the cell shrinkage, loss of filopodia and lamellipodia by phase contrast and SEM images in dose dependent manner. It has cytotoxic effects through inhibiting cellular proliferation, leads to the induction of apoptosis, as increased fraction of sub-G1 phase of the cell cycle,
chromatin condensation and
DNA ladder. It inhibited cyclin-D1 and
cyclin-E expression and induced p53, p21 expression in dose dependent manner. Consequently, an imbalance of Bax/Bcl-2 ratio triggered
caspase cascade and subsequent cleavage of PARP, thereby shifting the balance in favour of apoptosis.
PKI 166 treatment actively stimulated
reactive oxygen species (ROS) and mitochondrial membrane depolarization. It inhibited some metastatic properties of A431 cells supressing colony formation by soft
agar assay and inhibition of
MMP 9 activity by
gelatin zymography and western blot analysis.
PKI 166 inhibited
growth factor induced phosphorylation of EGFR, Akt, MAPK, JNK and colony formation in A431 cells. Thus the inhibition of proliferation was associated with redox regulation of the
caspase cascade, EGFR, Akt/PI3K, MAPK/ ERK and JNK pathway. On the other hand, increased
antioxidant activity leads to decreased ROS generation inhibit the anti-proliferative and apoptotic properties of
PKI 166 in A431 cells. These observations indicated
PKI 166 induced redox signalling dependent inhibition of cell proliferation, metastatic properties and induction of apoptotic potential in
epidermoid carcinoma.