Study On The Correlation Of Methylation Level Of MGMT Promoter And Ki-67 Or P53 In Pituitary Adenomas

Objectives: To examine whether MGMT promoter is methylated in pituitary adenoma,and to correlate the methylation level of MGMT promoter with the labelling indexes of Ki-67 and P53 expression if MGMT promoter is methylated,to assess whether the labelling indexes of Ki-67 and P53 as well as MGMT promoter methylation can predict the recurrence of pituitary adenoma and further guide the treatment of pituitary adenoma.Methods: Paraffin-embedded tissue sections were cut from 35 pituitary adenoma tissues that were collected from the Department of Pathology of Yijishan Hospital,Wannan Medical College from January 2020 to September 2022.Genomic DNA was extracted from these tissue sections using the DNA extraction kit for paraffin-embedded tissue and then subjected to DNA bisulfite conversion.The bisulfite converted genomic DNA samples were amplified by PCR with the methylation primer pairs of MGMT and non-methylation primer pairs for MGMT promoter,and then the PCR products were resolved by agarose gel electrophoresis to determine whether the MGMT promoter was methylated in the original pituitary adenoma samples.The labelling indexes of Ki-67 and P53 in the pituitary adenoma samples were obtained by immunohistochemical staining.Finally,the methylation level of MGMT promoter was correlated with the labelling index of Ki-67 at the intervals of <1%,1%-3%,or >3% and with the labelling index of P53 at the intervals of <50% or 50%.Results: The correlations of the MGMT promoter methylation level with the patients with pituitary adenoma at age of <60 years and 60 years were not found statistically significant(P values were 0.295 and0.420,respectively).Association of MGMT promoter methylation level with the different genders(male vs.female)were not statistically significant(P=0.226)in pituitary adenomas.The association between MGMT promoter methylation level and Ki-67 labelling index at the intervals of <1%,1-3%,or >3% were not statistically significant(P values were 0.573,0.712,0.784,respectively)in pituitary adenomas.The methylation level of MGMT promoter is not correlated with the P53 labelling indexes at the intervals of<50% or 50%(the P values were 0.608 and 0.999,respectively)in pituitary adenomas.Conclusions: 1.The recurrence of pituitary adenoma cannot be predicted by the labelling index of Ki-67 at the intervals of <1%,1%-3%,or >3%,or by the labelling index of P53 at the intervals of <50% or 50%.2.The methylation level of MGMT promoter and the labelling indexes of Ki-67 or P53 are not significantly correlated.Therefore,the labelling indexes of Ki-67 and P53 themselves as well as their correlations with the methylation level of MGMT promoter are not of great help in guiding the treatment of the patients with pituitary adenoma.