Conclusions PC-1NTP resulted in G0/G1 phase arrest and elicited an attenuating effect on the proliferation and apoptosis of cystic-lining epithelial ceils, which may be realized through regulating the expression of G1/S checkpoint regulation factor cyclinD1/p21~(WAF1) and apoptosis regulating protein bcl-2/bax.
PDT-mediated induction of G1/S checkpiont regulators Chk2 and p21WAF1/Cip1/Sdi1 results in the imposition of artificial checkpoint at G1-S transition thereby leading to an arrest of cells in G0-G1 phase of the cell cycle through inhibition in cyclinD1 in a time-dependent fashion;
3. With the presence of mutant p53 in SW480 cells, PDT results in the induction of p21WAF1/Cip1/Sdi1 and arrest of cell cycle in G0-G1 phase. The arrest of SW480 cell in G0-G1 phase by ALA-PDT may be mediated by activated G1-S checkpoint pathway independent of mutated p53
5. Immunocytochemistry and in situ hybridization analysis revealed that PDT resulted in an induction of G1/S checkpoint regulation factors such as Chk2 and p21WAF1/Cip1/Sdi1,and a down-regulation of cyclinD1 in a time-dependent fashion.
Results After MOLT-4 cells were irradiated by low dosage of X-ray (2,5 Gy),the content of G_1 cyclins (cyclin E) was decreased,but G_2 cyclins (Cyclin A,B1) increased quickly and accumulated distinctly in G_2 phase,indicating that G_2 checkpoint was activated.
However,after being irradiated by high dosage of X-ray(10,20 Gy),the content of G_1 cyclin (cyclin E) was increased quickly and accumulated distinctly in G_1/S phase,while G_2 cyclins (Cyclin A,B1) decreased gradually,indicating that G_1 checkpoint was activated.