Background: Everlasting cellular proliferation is the fundamental feature during gliomagenesis and Ki-67 is one of the classical proliferation markers in human glioblastoma multiforme (GBM). However, the driver genes or core pathways for cellular proliferation in GBM have not been elucidated systematically.
Methods: We evaluated by immunohistochemistry the prognostic value of Ki-67 expression in the clinical outcome of 156 Chinese patients with GBM and a total of 64 GBM samples were selected for further Agilent genome-wide microarray analysis. On the basis of the microarray data from Tiantan (n = 64) and The Cancer Genome Atlas (TCGA) (n = 202) database, differentially expressed genes between the GBM subgroups with high or low level of Ki-67 expression were identified using Significance Analysis of Microarrays (SAM). Gene Ontology (GO) and KEGG Pathway analyses were then undertaken for the Ki-67 associated genes to identify the most significant biological processes and signaling pathways.
Results: We confirmed that Ki-67 was an independent prognostic indicator in the largest Chinese patient cohort of 156 GBM samples via immunohistochemical staining. Survival analysis of Ki-67 over-expression revealed a highly significant association with a worse clinical outcome (P = 0.010 for progression-free survival; P = 0.007 for overall survival). Comparative and integrated analysis between Tiantan and TCGA database identified a 247-gene "proliferation signature" (205 up-regulated and 42 down-regulated genes) that distinguished Ki-67 expression phenotypes. GO and KEGG Pathway analyses further indicated that Ki-67 expression phenotype was associated with distinct changes in gene expression associated with the regulation of cellular growth and proliferation.
Conclusions: Proliferation marker Ki-67 is an independent prognostic indicator in Chinese GBM patients. And Ki-67 associated proliferation signature identified through genome-wide microarray analysis may provide potential targets for anti-proliferation therapy in GBM.