Figure 7.

Deficiency of LKB1 leads to nuclear abnormalities and multiploidy and correlates with elevated levels of phospho-PLK1 in colon and esophageal cancers. (a) Primary wild-type and null-LKB1 cells were fixed and the DNA was stained with DAPI. Morphology of nucleus was analyzed. Nuclear abnormalities were categorized as: mitotic delay, binuclear, polylobed, grape, large, and micronuclear. White arrows show the micronuclear or lagged nuclear components during the mitosis. (b) MEFs were transfected twice with siRNA LKB1 or control for a total of 96 h. The cells were then fixed and stained with propidium iodide and subjected to flow cytometry analysis for cell cycle distribution. (c) The average fold change of multiploidy cells in siRNA LKB1-treated MEFs as compared with control siRNA-treated MEFs. Error bar represents S.D. of three independent experiments. *P<0.05. (d) Representative IHC staining of LKB1 and PLK1 in serial human esophageal tissues from healthy controls and benign diseases (n=28) or cancers (n=52). Scale bar=80 μm. (e) Quantitation of LKB1 and PLK1 expression in human esophageal disease spectrum tissues. Masked reading was performed by three different investigators with the same criteria to evaluate the staining (low, overall negative, or weak staining; high, overall moderate, or strong staining). Pearson's χ²-test was used to analyze the distribution difference of PLK1 or LKB1 between benign and cancer tissues (P>0.05). (f) Assessment of phospho-PLK1-T210 in esophageal tissues in (e) by IHC. H-scores of phospho-PLK1 in LKB1 low- and high-expression cells were calculated (see Materials and Methods for an explanation of H-scores). Pearson's χ²-test was used to analyze the significance of the correlation (*P<0.05)