In contrast, OE33 and markedly OE19 and EPC hTERT cells had a high G0 G1 phase population, with reduced S and G2 M phase populations. Aurora kinases in normal esophageal epithelial cells and esophageal cancer cells For Aurora A, fluorescence in situ hybridization revealed sellectchem chromosome 20 polysomy with concomitantly elevated Aurora A gene copy num bers in OE21, OE33 and OE19 cells and an Aurora A gene amplification with up to nine Aurora A gene copies in Kyse 410 cells. In view of their Aurora A gene amplification, Kyse 410 cells also showed highest Aur ora A mRNA and high protein expression. In contrast, OE21, OE33 and OE19 cells exhibited lower Aurora A mRNA expression, despite chromosome 20 polysomy. Still, high Aurora A protein expression was seen in OE33, but not OE21 and OE19 cells.
Active Aurora A was hardly detectable in immunoblot analysis, but weak Aur ora A phosphoT288 levels were seen in OE21, Kyse 410 and OE33 cells. Control EPC hTERT cells had normal diploid Aurora A gene copy numbers, lowest Aurora A mRNA expression, but detectable strong Aurora A and weak Aurora A phosphoT288 protein levels. For Aurora B, chromosome 17 polysomy and concomitantly elevated Aurora B gene copy numbers were observed by FISH in the ESCC cell lines OE21 and Kyse 410. Interestingly, in the BAC cell lines OE33 and OE19 elevated chromosome 17 specific signals with lower Aurora B gene specific signals, result ing in Aurora B to chromosome 17 ratios below 1, were observed. Accordingly, both ESCC cell lines had slightly higher Aurora B mRNA and protein expression than the BAC cell lines.
Active Aurora B was apparent in OE21, Kyse 410 and OE33 cells. Control EPC hTERT cells had normal diploid Aurora B gene copy numbers, similar Aurora B mRNA as BAC cell lines, but undetectable Aurora B protein expression or activity. The low Aurora B gene copy numbers and protein expression in the two BAC cell lines were not due to a general phenomenon of entire chromosome 17 altera tions, since HER2 gene copy numbers were highly amplified in these two cell lines. Thus, Aurora A and B gene copy numbers are linked to mRNA expression patterns, but this is not directly translated into altered protein or activity levels. Whilst high Aurora A and Aurora B protein levels largely reflect DNA copy numbers as well as cell cycle distribu tion in some cell lines, decoupling of Aurora A and or B gene copy numbers with expression and cell cycle distribution occurs in other cell lines.
High Aurora A expression alone is not associated with occurrence of multipolar mitoses in esophageal cancer cells Aurora A gene amplification Batimastat and protein overexpression have been linked to the occurrence of supernumerary centrosomes, formation of multipolar mitoses and aneu ploidy. We therefore next examined the occur rence of Aurora A positive multipolar mitoses in the EPC hTERT as well as the four esophageal cancer cell lines.