Objective: To observe the changes in glioma growth characteristic and apoptosis of tumor cells after single handed continuous low-dose chemotherapy, cyclooxygenase-2 inhibitor treatment alone and the combination of the two treatments.
Methods: The U251MG cells in exponential phase of growth were made into 10(7)/mL cell suspension in free-serum 1640 and stored in 37 degrees C incubator. The survival rate of cells was above 95%. The U251MG cells were implanted into the right parietooccipital lobe of the 4-week old nude mouse with a 5 micro liter micro amount sample injector. The number of injected U251MG cells was 5 x 10(4) for a mouse. Twenty days after the model making, the nude mice were treated with elemene and indometacin respectively and the combination of them, twice a week. The mice were divided into four groups. Group I was treated with indometacin alone, group II elemene alone, group III low-dose elemene plus indometacin, Group IV was used as controls, including tumor control and blank control. The animals were killed on the 40th and 50th day after implantation by breaking cervical vertebra. The fixed brain was made into 3 microm slices by paraffin section. The slices were carried out with HE staining and immunohistochemical staining of glial fibrillary acidic protein(GFAP), cell proliferation-associated antigen(Ki-67), cyclooxygenase-2(COX-2), CD34, programmed cell death 5(PDCD5) and terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labeling(TUNEL).
Results: The proliferation of glioma cells was predominant in the tumor control mouse brain. Several immature blood vessels were observed in the tumor implanted for 40 days. The white matter was infiltrated by bulk glioma cells along with capillary vessel clusters in the mouse brain implanted for 50 days. In groups with combination treatment of the two drugs, 40 days after the implantation, several apoptosis cells and glioma cells were observed in tumor where the positive signal for GFAP was showed; and 50 days after the implantation, lots of apoptosis cells were observed in tumor cell implantation area where the negative signal for GFAP and positive signal for PDCD5 was showed. The volume of tumor was (29.8+/-39.1) mm(3) 40 days after the implantation, and (78.4+/-125.9) mm(3) 50 days after the implantation. There was no statistically significant difference in tumor volume among groups(P=0.11).
Conclusion: The combination of two treatments could merely prolong the survival time of the nude mouse model, without the effect of eliminating the tumor completely.