OBJECTIVETo observe the effect of polo like kinase 1 (plk1) gene depletion on the growth of gastric cancer cell line-MKN45 cells in vitro and vivo and discuss the feasibility and effectiveness of arranging plk1 as gene therapeutic target for gastric cancer.

METHODSThe plk1 expression of MKN45 cells was inhibited by RNA interference (RNAi). The plk1 mRNA and protein level were measured by real-time quantitative PCR and western blotting, and the change of cell cycle distribution and apoptosis rate were detected by flow-cytometry, and the MKN45 cells proliferation was measured by MTT method. MKN45 cells treated with plk1 siRNA were transplanted subcutaneously in nude mice and their tumorgenesis ability were observed, the plk1 protein levels of the samples from nude mice in different groups were compared.

RESULTSAfter treatment with plk1 siRNA, plk1 mRNA and protein level decreased obviously in certain time, more MKN45 cells accumulated at G(2)/M (P < 0.05). Apoptosis rate of MKN45 cells treated with plk1 siRNA was higher than that of control cells at 48 h and 72 h (P < 0.05), and MKN45 cells proliferated slowly than control groups (P < 0.05), while the tumorgenesis ability obviously decreased, but the plk1 protein levels of the samples from nude mice in different groups were not different.

CONCLUSIONSsiRNA targeting plk1 can inhibit the proliferation of MKN45 cells in vitro and vivo. Plk1 may be a novel therapeutic target for gastric cancer.

Animals ; Apoptosis ; drug effects ; Cell Cycle Proteins ; drug effects ; genetics ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Male ; Mice ; Mice, Nude ; Protein-Serine-Threonine Kinases ; drug effects ; genetics ; Proto-Oncogene Proteins ; drug effects ; genetics ; RNA Interference ; RNA, Small Interfering ; genetics ; pharmacology ; Stomach Neoplasms ; drug therapy ; enzymology ; pathology ; Transfection

Although medical treatment has been shown to improve quality of life and prolong survival, no significant progress has been made in the treatment of advanced gastric cancer (AGC) within the last two decades. Thus, the optimum standard first-line chemotherapy regimen for AGC remains debatable, and most responses to chemotherapy are partial and of short duration; the median survival is approximately 7 to 11 months, and survival at 2 years is exceptionally > 10%. Recently, remarkable progress in tumor biology has led to the development of new agents that target critical aspects of oncogenic pathways. For AGC, many molecular targeting agents have been evaluated in international randomized studies, and trastuzumab, an anti-HER-2 monoclonal antibody, has shown antitumor activity against HER-2-positive AGC. However, this benefit is limited to only ~20% of patients with AGC (patients with HER-2-positive AGC). Therefore, there remains a critical need for both the development of more effective agents and the identification of molecular predictive and prognostic markers to select those patients who will benefit most from specific chemotherapeutic regimens and targeted therapies.
Angiogenesis Inhibitors/therapeutic use ; Animals ; Antineoplastic Agents/*therapeutic use ; Humans ; *Molecular Targeted Therapy ; Protein Kinase Inhibitors/therapeutic use ; Receptor, Epidermal Growth Factor/antagonists & inhibitors/metabolism ; Receptor, erbB-2/antagonists & inhibitors/metabolism ; Signal Transduction/drug effects ; Stomach Neoplasms/*drug therapy/enzymology/genetics/pathology ; Treatment Outcome