Development of membrane anatomy theory in gastric cancer surgery / 中华胃肠外科杂志

In the past decade, the concept of membrane anatomy has been gradually applied in gastric cancer surgery. Based on this theory, D2 lymphadenectomy plus complete mesogastric excision (D2+CME) has been proposed, which has been demonstrated to significantly reduce intraoperative bleeding and intraperitoneal free cancer cells during surgery, decrease surgical complications, and improve survival. These results indicate that membrane anatomy is feasible and efficacious in gastric cancer surgery. In this review, we will describe the important contents of membrane anatomy, including "Metastasis V"(2013, 2015), proximal segmentation of dorsal mesogastrium (2015), D2+CME procedure (2016), "cancer leak"(2018), and surgical outcomes of D2+CME (2022).

Demonstration and significance on proximal segment of dorsal mesogastrium / 中华胃肠外科杂志

In radical gastrectomy, D2 systemic lymphadenectomy, which includes complete resection of the bursa sac and omentum, and D2 extended lymphadenectomy outside the bursa sac, is a standard procedure accepted by gastrointestinal surgeons generally. However, a series of clinical trials showed that both D2 extended lymphadenectomy and bursectomy could not improve oncologic benefit, but increase surgical risk. These findings showed a lot of conflicts in gastric cancer surgery, gastrointestinal surgery, even in oncological surgery. It was demonstrated that bursa sac and greater omentum were neither mesogastrium nor the proximal segment of dorsal mesogastrium (PSDM), which has been identified recently. Local physiological structures (such as blood vessels and lymphatic nodes) and pathological events (such as lymph nodes metastasis and metastasis V) only occur in mesentery in broad sense (i.e. PSDM). Broken PSDM during radical gastrectomy can result in cancer cell leakage into the operational field. Therefore, complete PSDM excision in the D2 field (D2+CME) is suggested as a better procedure for local advanced gastric cancer, which can get benefits not only in surgical hazard, but also in oncologic result. The results of PSDM research could lead to three changes: (1) resolving some long standing problems in gastric cancer surgery, gastrointestinal surgery, and even oncologic surgery; (2) opening an new era for finding and utilizing extra-intestinal mesentery in broad sense; (3) formulating the theory of membrane anatomy which may update, iterate and upgrade related information of classical anatomy, pathology, surgery and oncology.

Silencing of cell cycle checkpoint kinase gene enhances cisplatin-induced apoptosis of lung cancer cells / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the changes in cell cycle induced by cisplatin (DDP) and the effect of antisense oligonucleotide (AsODN) targeting Chk1/2 on DDP-induced apoptosis in lung cancer cell line A549 cells.</p><p><b>METHODS</b>The characteristics of cell cycle and apoptosis induced by DDP were detected by flow cytometry using SubG1 method. Chk1/2 mRNA and protein expression were assayed by RT-PCR and Western blot under best condition of transfection of AsODN targeting Chk1/2 by lipofection. Apoptosis of A549 cells induced by DDP was determined by flow cytometry using AnnexinV-FITC staining after transfection of Chk1/2 AsODN.</p><p><b>RESULTS</b>Asynchronized A549 cells were treated with 10 micromol/L DDP, and significant S-phase arrest was observed at 12 h later. Transfection with antisense oligonucleotide targeting Chk1/2 inhibited the Chk1/2 expression at both mRNA and protein levels. Either Chk1 or Chk2-specific AsODN consistently enhanced DNA damage-induced apoptosis by 100% - 200%, compared with that in the sODN control (P < 0.05), but combined use of Chk1- and Chk2-specific AsODN did not show synergistic effects as compared with that induced by treatment with Chk1- or Chk2-specific AsODN alone (P > 0.05).</p><p><b>CONCLUSION</b>Chk1 and Chk2 may be regarded as effective targets of chemotherapy for lung cancer. Silencing the key effector Chk1 and Chk2 genes may significantly increase the chemosensitivity of lung cancer cells.</p>

Down-regulation of Chk1/Chk2 gene expression increases apoptosis in irradiated HeLa cells and its mechanism / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To explore the increasing effect of blocking Chk1 and /or Chk2 gene by Chk1 or Chk2-specific antisense oligodeoxynucleotides (AsODN) on apoptosis in HeLa cell line after irradiation and its mechanism of action.</p><p><b>METHODS</b>Asynchronized HeLa cells were exposed to (60)Co-irradiation at different dosage to activate G(2)/M checkpoint arrest. The cell cycle profiles were observed in HeLa cells after irradiation at a range of various doses and different time points by flow cytometry. In the experimental groups, Chk1/2 sODN and AsODN alone or in combination were transfected into HeLa cells, and the cells were exposed to (60)Co-irradiation at 24 h after transfection. The changes of Chk1/2 protein expression were assayed by Western blot and confocal laser scanning microscopy (Confocal), and the cell cycles, apoptosis rates and cell cycle specific apoptosis were detected by annexin V-PI labeling and flow cytometry.</p><p><b>RESULTS</b>Apoptotic response was significantly increased in the Hela cells after G(2)/M arrest and was inversed to activation of G(2)/M checkpoint. Either Chk1 or Chk2-specific AsODN consistently enhanced DNA damage-induced apoptosis by 90% approximately 120%, compared to corresponding sODN control (P < 0.05). Unexpectedly, combined use of Chk1- and Chk2-specific AsODN did not produce synergistic effect as compared to treatment with Chk1- or Chk2-specific AsODN alone (P > 0.05). While irradiated HeLa cells underwent apoptosis preferentially in G(1)-phase, apoptosis occurred in either of G(1)-, S- or G(2)/M -phase in the presence of Chk1 and/or Chk2 AsODN.</p><p><b>CONCLUSION</b>The radioresistance is mainly induced by activating the cell cycle checkpoint signal transduction pathway after irradiation, and abrogating of the key effector Chk1 and Chk2 may increase the apoptotic sensitivity to irradiation due to changes of the pattern of cell cycle specific apoptosis.</p>

PTEN induces anoikis through its phosphatase activity in hepatocellular carcinoma cells / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To investigate the effect and mechanisms of tumor suppressor gene PTEN on the induction of anoikis of hepatocellular carcinoma SMMC-7721 cells.</p><p><b>METHODS</b>SMMC-7721 cells were transfected with GFP plasmids containing wild-type PTEN or phosphatase inactivating mutant PTEN (C124A-PTEN) in vitro; The PTEN expression and the phosphorylation levels of focal adhesion kinase (FAK) and protein kinase B (PKB/Akt) were detected by Western blotting; Flow cytometry assay and laser scanning confocal microscopy were used to analyze apoptosis in adherent and non-adherent cells.</p><p><b>RESULTS</b>Compared with the control, PTEN expression in the cells transfected with wild-type PTEN increased to 248%, while the phosphorylation level of FAK and Akt decreased 65.2% and 89.1%, respectively; and the anoikis percentage increased from 9.5% to 31.3%. In the cells transfected with C124A-PTEN, neither the phosphorylation of FAK and Akt nor the anoikis percentage had obviously changed, although the PTEN expression enhanced dramatically in comparison with the control.</p><p><b>CONCLUSION</b>Through its phosphatase activity, tumor suppressor gene PTEN can suppress the phosphorylation of FAK and Akt, and induce anoikis in hepatocellular carcinoma cells.</p>

PTEN induces apoptosis and up-regulates p53 expression in HepG2 cells / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the effects of tumor suppressor gene PTEN on apoptosis and protein expression of p53 in HepG2 cells, as well as to explore its mechanisms.</p><p><b>METHODS</b>HepG2 cells were transfected with GFP plasmids containing wild-type PTEN or G129E-PTEN and C124A-PTEN in vitro. Both the expression of wild-type p53 and the phosphorylation of protein kinase B (PKB/Akt) and focal adhesion kinase (FAK) were detected by Western blotting. Flow cytometry and confocal microscopy were used to analyze apoptosis of the transfected cells.</p><p><b>RESULTS</b>Compared with the control, the expression of phosphorylated FAK and phosphoylated Akt were down-regulated in HepG2 cells transfected with wild-type PTEN (-65%, -93%) and G129E-PTEN (-65%, -35%), whereas the apoptosis percentage increased to (19.8+/-1.2)% and (9.2+/-0.6)%, and p53 expression was up-regulated by 120% and 50%, respectively. However, in the cells transfected with C124A-PTEN, neither the phosphorylation of FAK and Akt nor the apoptosis percentage and p53 expression had changed.</p><p><b>CONCLUSION</b>PTEN can dephosphrylate FAK through its protein phosphatase activity, and suppress phosphorylation of Akt mainly through its lipid phosphatase activity. Consequently, it can induce apoptosis of HepG2 cells and up-regulate p53 expression.</p>