Effects of HIF-1alpha on human gastric cancer cell apoptosis at different CO(2) pressures

HIF in Gastric Cancer: Regulation and Therapeutic Target

HIF means hypoxia-inducible factor gene family, and it could regulate various biological processes, including tumor development. In 2021, the FDA approved the new drug Welireg for targeting HIF-2a, and it is mainly used to treat von Hippel-Lindau syndrome, which demonstrated its good prospects in tumor therapy. As the fourth deadliest cancer worldwide, gastric cancer endangers the health of people all across the world. Currently, there are various treatment methods for patients with gastric cancer, but the five-year survival rate of patients with advanced gastric cancer is still not high. Therefore, here we reviewed the regulatory role and target role of HIF in gastric cancer, and provided some references for the treatment of gastric cancer.

High-pressure artificial pneumothorax promotes invasion and metastasis of oesophageal cancer cells

OBJECTIVES

This study aimed to investigate the viability, apoptosis, invasion and metastasis of oesophageal cancer cells in a simulated artificial pneumothorax model and to explore its potential mechanism of action.

METHODS

Oesophageal cancer cells were subjected to a simulated thoracoscopic CO2 pneumothorax environment with different pressures and exposure times (low-pressure group: 8 mmHg 1 h or 8 mmHg 4 h; high-pressure group: 12 mmHg 1 h). Cell viability, apoptosis, invasive capacity and mRNA expression of adhesion- and metastasis-related molecules in each group were detected. To explore in greater detail the potential reasons for the changes in biological behaviour under the high-pressure CO2 environment, we designed 3 additional experimental groups: (i) high-pressure group, (ii) hypoxia group and (iii) pH decrease group. An miRNA microarray analysis was performed by comparing 2 paired samples of cells from the high-pressure group and the control group.

RESULTS

Treatment with high-pressure CO2 pneumothorax significantly increased the cell viability (P < 0.001) and the cell invasion (P < 0.001). Significantly higher expression of adhesive- and metastasis-related molecules was also observed. Further experiments indicated that the high-pressure CO2 pneumothorax might increase cell invasion and metastasis through the high pressure and decreased pH. The miRNA microarray analysis results suggested that several potential pathways related to cancer development: the RhoA pathway, the PI3K-Akt signalling pathway and the MAPK signalling pathway.

CONCLUSIONS

The application of high-pressure CO2 pneumothorax promoted the invasion and metastasis of oesophageal cancer cells through high pressure and decreased pH. This process might be related to several signalling pathways.

Comparison of laparoscopy-assisted and open radical gastrectomy for advanced gastric cancer: A retrospective study in a single minimally invasive surgery center

Laparoscopy-assisted gastrectomy (LAG) has gained international acceptance for the treatment of early gastric cancer (EGC). However, the use of laparoscopic surgery in the management of advanced gastric cancer (AGC) has not attained widespread acceptance. This retrospective large-scale patient study in a single center for minimally invasive surgery assessed the feasibility and safety of LAG for T2 and T3 stage AGC. A total of 628 patients underwent LAG and 579 patients underwent open gastrectomy (OG) from Jan 2004 to Dec 2011. All cases underwent radical lymph node (LN) dissection from D1 to D2+. This study compared short- and long-term results between the 2 groups after stratifying by pTNM stages, including the mean operation time, volume of blood loss, number of harvested LNs, average days of postoperative hospital stay, mean gastrointestinal function recovery time, intra- and post-operative complications, recurrence rate, recurrence site, and 5-year survival curve. Thirty-five patients (5.57%) converted to open procedures in the LAG group. There were no significant differences in retrieved LN number (30.4 ± 13.4 vs 28.1 ± 17.2, P = 0.43), proximal resection margin (PRM) (6.15 ± 1.63 vs 6.09 ± 1.91, P = 0.56), or distal resection margin (DRM) (5.46 ± 1.74 vs 5.40 ± 1.95, P = 0.57) between the LAG and OG groups, respectively. The mean volume of blood loss (154.5 ± 102.6 vs 311.2 ± 118.9 mL, P < 0.001), mean postoperative hospital stay (7.6 ± 2.5 vs 10.7 ± 3.6 days, P < 0.001), mean time for gastrointestinal function recovery (3.3 ± 1.4 vs 3.9 ± 1.5 days, P < 0.001), and postoperative complications rate (6.4% vs 10.5%, P = 0.01) were clearly lower in the LAG group compared to the OG group. However, the recurrence pattern and site were not different between the 2 groups, even they were stratified by the TNM stage. The 5-year overall survival (OS) rates were 85.38%, 79.70%, 57.81%, 34.60% and 88.31%, 75.49%, 56.84%, 33.08% in patients with stage Ib, IIa, IIb, and IIIa, respectively, in the LAG and OG groups. There were no statistically significant differences in the OS rate for patients with the same TNM stage between the 2 groups. LAG with radical LN dissection is a safe and technically feasible procedure for the treatment of AGC staged below T3.

Lethal effect of a hyperthermic CO₂ pneumoperitoneum on gastric cancer cells

OBJECTIVES

We investigated the lethal effect of a hyperthermic CO₂ pneumoperitoneum on gastric cancer cells. This could form the theoretical basis for further studies of the feasibility and safety of inflating hyperthermic CO₂ in the abdominal cavity of gastric cancer patients during laparoscopy.

METHODS

An in vitro hyperthermic CO₂ pneumoperitoneum experimental model was built, where gastric cancer cell line SGC-7901 cells were grouped according to temperature. Cytotoxicity was detected using a cell counting kit; apoptosis was detected by Annexin V-FITC/PI flow cytometry and Hoechst 33342/PI fluorescent microscopy. Morphological alterations were observed by transmission electron microscopy. Invasion and migration were detected by a scratch test and by transwell migration, respectively.

RESULTS

Cytotoxicity assays showed that a hyperthermic CO₂ pneumoperitoneum significantly inhibited the proliferation of SGC-7901 cells (P<0.05); it also significantly induced apoptosis of SGC-7901 cells (P<0.05). Morphological observations showed that the cell membrane and nucleus had an apoptotic phenotype. The invasiveness and migration ability of the gastric cancer cells subjected to hyperthermic CO₂ were significantly reduced.

CONCLUSIONS

A hyperthermic CO₂ pneumoperitoneum had a lethal effect on gastric cancer SGC-7901 cells by inhibiting their invasion and migration, and by inducing apoptosis.

GSTM3 reverses the resistance of hepatoma cells to radiation by regulating the expression of cell cycle/apoptosis-related molecules

Radiotherapy (RT) is a major modality of hepatoma treatment. However, liver tumors often acquire radioresistance, which contributes to RT failure. The exact mechanisms of the radioresistance in hepatoma cells are largely unknown. Glutathione S-transferase M3 (GSTM3) is a phase II transferase, however, recent studies have suggested that GSTM3 is a potential tumor suppressor. The purpose of the present study was to investigate the role of GSTM3 in reversing radioresistance, and to explore the molecular mechanism of this in the human radiation-resistant PRF/PLC/5R hepatocellular carcinoma (HCC) cell line. The radioresistant PLC/PRF/5R cells were used as cell model, and were derived from PLC/PRF/5 parental cells using fractionated irradiation. The radiosensitivity of the cells was tested by clonogenic assay and flow cytometry analyses. The expression of B-cell chronic lymphocytic leukemia/lymphoma 2 (Bcl-2), Bax, p21, p27 and p53 was analyzed by quantitative polymerase chain reaction and immunoblotting with or without radiation. The results showed that the expression levels of GSTM3 were significantly lower in the PLC/PRF/5R cells than in the PLC/PRF/5 parental cells. GSTM3 overexpression sensitized the PLC/PRF/5R cells to radiation mainly though induction of apoptosis. According to the evidence from Annexin-V/PI staining, it markedly increased the percentage of apoptotic PRF/PLC/5R cells. The clonogenic assay indicated that GSTM3 significantly decreased the RT survival fraction in PRF/PLC/5R cells. Furthermore, GSTM3 increased the expression of cell cycle- and apoptosis-related genes (Bcl-2, Bax, p21, p27 and p53) in PRF/PLC/5R cells with irradiation. These findings suggest that GSTM3 plays an pivotal role in reversing the radioresistance of HCC and may be a potential target for sensitizing HCC cells to RT. The underlying mechanisms may be linked to the cell cycle arrest and apoptosis facilitation.

Transcutaneous application of carbon dioxide (CO2) induces mitochondrial apoptosis in human malignant fibrous histiocytoma in vivo

Mitochondria play an essential role in cellular energy metabolism and apoptosis. Previous studies have demonstrated that decreased mitochondrial biogenesis is associated with cancer progression. In mitochondrial biogenesis, peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) regulates the activities of multiple nuclear receptors and transcription factors involved in mitochondrial proliferation. Previously, we showed that overexpression of PGC-1α leads to mitochondrial proliferation and induces apoptosis in human malignant fibrous histiocytoma (MFH) cells in vitro. We also demonstrated that transcutaneous application of carbon dioxide (CO₂) to rat skeletal muscle induces PGC-1α expression and causes an increase in mitochondrial proliferation. In this study, we utilized a murine model of human MFH to determine the effect of transcutaneous CO₂ exposure on PGC-1α expression, mitochondrial proliferation and cellular apoptosis. PGC-1α expression was evaluated by quantitative real-time PCR, while mitochondrial proliferation was assessed by immunofluorescence staining and the relative copy number of mitochondrial DNA (mtDNA) was assessed by real-time PCR. Immunofluorescence staining and DNA fragmentation assays were used to examine mitochondrial apoptosis. We also evaluated the expression of mitochondrial apoptosis related proteins, such as caspases, cytochorome c and Bax, by immunoblot analysis. We show that transcutaneous application of CO₂ induces PGC-1α expression, and increases mitochondrial proliferation and apoptosis of tumor cells, significantly reducing tumor volume. Proteins involved in the mitochondrial apoptotic cascade, including caspase 3 and caspase 9, were elevated in CO₂ treated tumors compared to control. We also observed an enrichment of cytochrome c in the cytoplasmic fraction and Bax protein in the mitochondrial fraction of CO₂ treated tumors, highlighting the involvement of mitochondria in apoptosis. These data indicate that transcutaneous application of CO₂ may represent a novel therapeutic tool in the treatment of human MFH.