Polo like kinase 1 expression and prognostic value in gastric carcinomas / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To identify the expression of polo like kinase 1 (plk1) and to discuss its relationship with the clinicopathological parameters and prognosis in gastric carcinoma.</p><p><b>METHODS</b>Plk1 protein expression levels in 89 cases of resected gastric carcinomas were detected by immunohistochemistry method, the relations between plk1 expression levels and the survival periods were estimated by Kaplan-Meier curve.</p><p><b>RESULTS</b>The positive rate of plk1 expression in gastric cancer tissues was 42.7% (38/89), significantly higher than that (13.5%) in the adjacent noncancerous tissues (12/89) (P<0.01). The expression levels of plk1 were closely related to tumor differentiation, invasion and TNM stage (P<0.05). Patients with plk1-positive expression had worse prognosis than those with plk1-negative expression in gastric cancer patients (P<0.05).</p><p><b>CONCLUSIONS</b>Plk1 may promote carcinogenesis and gastric cancer development, its overexpression can be a novel marker for diagnosing certain biological behaviours and predicting prognosis in gastric cancer.</p>

Inhibition of polo like kinase gene expression induces apoptosis in gastric cancer cells / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To observe the effect of inhibition of polo like kinase1 (plk1) gene expression on apoptosis induction in gastric cancer cell line-MKN45 and discuss the vital role of plk1 proliferation and viability of gastric cancer cells.</p><p><b>METHODS</b>The plk1 expression was inhibited by chemically synthesized siRNA. The plk1 mRNA and protein level were respectively measured by real-time quantitative PCR and Western blotting. The spindle morphological change was observed by immunofluorescence staining and confocal microscopy. The change of cell cycle distribution and apoptosis rate was detected by flow-cytometry. Pro caspase3 level was also detected by western blotting.</p><p><b>RESULTS</b>After treatment by siRNA targeting plk1, plk1 mRNA and protein level decreased obviously, the cell mitotic spindle became obscure and lost cohesiveness, more MKN45 cells accumulated at G(2)/M phase (P< 0.05), apoptosis rate of plk1 siRNA treated MKN45 cells was higher than that of control cells at 48 h and 72 h (P< 0.05) with pro-caspase3 level decreasing at 72 h.</p><p><b>CONCLUSIONS</b>Inhibition of plk1 gene expression induces apoptosis in MKN45 cells through the pathway of caspase3. Plk1 gene play a key role in viability of MKN45 cells.</p>

Analysis of gene expression profiles in gastric cancer cell cycle / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To detect the gene expression profile in gastric cancer cell cycle and explain the mechanism of gastric cancer cell proliferation by a genomic study.</p><p><b>METHODS</b>Gastric cancer cells MKN45 were synchronized at G2/M and G1/S point by nocodazole-thymidine and double thymidine methods. The synchronizing degree of cells was monitored by flow cytometry. The gene expression profiles at G2/M point, M/G1 transition, G1 early phase, G1 late phase, G1/S point, S early phase, S late phase, G2 early phase and G2 late phase in MKN45 cell cycling were examined using cDNA microarray chips. Hierarchy analysis was conducted with a professional software package and the up-regulated genes at G1 late and G2 phase were analyzed according to gene database. Furthermore, the mRNA level of cyclin E, cyclin B, plk1 and STK15 in above mentioned nine points were measured by quatitative PCR.</p><p><b>RESULTS</b>2001 genes were detected to be available at all 9 points via software processing, out of which 959 appeared up-regulated or down-regulated. 379 genes showed to be up-regulated at late G1 (147) or G2 phases (232), 40 at S and M phases (also up-regulated at G1 late and G2 phases). The 147 up-regulated genes at G1 late phase are involved in DNA metabolism, transcription and translation, protein transportation, ubiquitination and signal transduction, etc. The 232 up-regulated genes in G2 phase are involved in RNA synthesis and processing, intracellular protein transportation, cytoskeleton synthesis, signal transduction, apoptosis and anti-apoptosis, transcription regulation, ubiquitination, mitosis regulation and oncogene expression, etc. The mRNA level of 4 genes detected by quantitative PCR during cell cycle was in agreement with that detected by microarray.</p><p><b>CONCLUSION</b>During MKN45 cell cycling, the preparation for DNA synthesis and chromosome separation are conducted in G1 and G2, which are implicated in multiple genes, may be the main impetus of driving MKN45 cell cycle. Some of these genes may be related to tumor over-proliferation. The cDNA microarray technique has characteristic features such as reliability and can provide a great deal for future research on cell cycle related genes in gastric cancer.</p>