Expression and significance of PTEN, hypoxia-inducible factor-1 alpha in colorectal adenoma and adenocarcinoma

AIM: To investigate the expression and significance of PTEN,hypoxia-inducible factor-1 alpha (HIF-1α), and targeting gene VEGF during colorectal carciogenesis.METHODS: Total 71 cases colorectal neoplasms (9 cases of colorectal adenoma and 62 colorectal adenocarcinoma)were formalin fixed and paraffin-embedded, and all specimens were evaluated for PTEN mRNA, HIF-1α mRNA and VEGF protein expression. PTEN mRNA, HIF-1α mRNA were detected by in situ hybridization. VEGF protein was identified by citrate-microwave SP immunohistochemical method.RESULTS: There were significant differences in PTEN, HIF1α and VEGF expression between colorectal adenomas and colorectal adenocarcinoma (P＜0.05). The level of PTEN expression decreased as the pathologic stage increased.Conversely, HIF-1α and VEGF expression increased with the Dukes stage as follows: stage A (0.1029±0.0457:0.1207± 0.0436), stage B (0.1656±0.0329: 0.1572±0.0514),and stage C+D (0.2335±0.0748: 0.2219±0.0803). For PTEN expression, there was a significant difference among Dukes stage A, B, and C+D, and the level of PTEN expression was found to be significant higher in Dukes stage A or B than that of Dukes stage C or D. For HIF-1α expression,there was a significant difference between Dukes stage A and B, and the level of HIF-1α expression was found to be significantly higher in Dukes stage C+D than that of Dukes stage A or B. The VEGF expression had similar results as HIF-1α expression. In colorectal adenocarcinoma,decreased levels of PTEN were significantly associated with increased expression of HIF-1α mRNA (r=-0.36, P＜0.05)and VEGF protein (r=-0.48, P＜0.05) respectively. The levels of HIF-1 were positively correlated with VEGF expression (r=0.71, P＜0.01).CONCLUSION: Loss of PTEN expression and increased levels of HIF-1α and VEGF may play an important role in carcinogenesis and progression of colorectal adenocarcinoma.

Perioperative cimetidine administration promotes peripheral blood lymphocytes and tumor infiltrating lymphocytes in patients with gastrointestinal cancer:Results of a randomized controlled clinical trial

AIM: To study the effects of perioperative administration of cimetidine (CIM) on peripheral blood lymphocytes, natural killer (NK) cells and tumor infiltrating lymphocytes (TIL) in patients with gastrointestinal (GI) cancer. METHODS: Forty-nine GI cancer patients were randomized into treatment group, who took CIM in perioperative period,and control group, who did not take the drug. The treatment was initiated 7 days before operation and continued for 10 days after surgery. At baseline examination before operation, on the 2rid and 10th postoperative days, total T lymphocytes, T helper cells, T suppressor cells, and NK cells in peripheral blood were measured respectively by immunocytochemical method using mouse-anti human CD3,CD4, CD8 and CD57 monoclonal antibodies. Blood samples from 20 healthy volunteers were treated in the same way as normal controls. Surgical specimens were examined during routine histopathological evaluation for the presence of TiL in tumor margin. Immunohistochemical study was performed to measure the proportion of T and B lymphocytes in T[L population. T and B lymphocytes were detected respectively using mouse-anti-human CD3 and CD20 monoclonal antibodies. RESULTS: in comparison with normal controls, both the treatment and control groups had decreased T cells, T helper cells and NK cells at baseline. In control group, total T cells,T helper cells and NK cells declined continuously with the disease progression and the decrease became more obvious after operation. From baseline to the 2nd postoperative day,the proportion of total T cells, T helper cells, and NK cellswent down from 60.5±4.6% to 56.2±3.8%, 33.4±3.7% to28.1±3.4%, and 15.0±2.8% to 14.2±2.2%, respectively.On the other hand, there were significant improvements in these parameters after CIM treatment. On the 10th postoperative day, the treatment group had significantly higher percentages of total T cells, T helper cells and NK cells than control group. Moreover, CIM treatment also boosted TiL response, as was reflected by findings that 68%(17/25) of the patients in treatment group had significant TIL responses and only 25% (6/24) of the cases had discernible TIL responses (P<0.01). CONCLUSION: Perioperative application of CIM to GI cancer patients could help restore the diminished cellular immunity induced by tumor burden and surgical maneuver. The drug could also boost TIL responses to tumor. These effects suggest that the drug be used as an immunomodulator for GI cancer patients.

Telomerase activity and cell apoptosis in colon cancer cell by human telomerase reverse transcriptase gene antisense oligodeoxynucleotide

AIM: To evaluate the effect of human telomerase reverse transcriptase (hTERT) gene antisense oligodeoxynudeotide (As-ODN) on telomerase activity and cell apoptosis in colon cancer cell line SW480.METHODS: As-ODN was transfected into cells SW480 by liposomal transfection. Cultured cells were divided into three groups: ASODN (5′GGAGCGCGCGGCATCGCGGG-3), sense oligodeoxynucleotide (5′-CCCGCGATGCCGCGCGCTCC-3; SODN) and control. The concentration of oligodeoxynucleotide and lipsome was 10 μmol/L and 16 mg/L, respectively. The activity of telomerase was examined by telomeric repeat amplification protocol (TRAP)-enzyme-linked immunosorbent assay (ELISA), and cell apoptosis was observed by morphology and flow cytometry in each group.RESULTS: Telomerase activity began to be down-regulated or inhibited when cells SW480 were treated with As-ODN for 72 h, and cell apoptosis was induced.CONCLUSION: It is suggested that hTERT As-ODN might specially inhibit the activity of telomerase in colon cancer cells and it is further proved that the hTERT gene has a significant correlation with telomerase activity. Further evidence is needed to prove whether hTERT As-ODN is a potential tool for the treatment of colon cancer.

Effect of antisense oligodeoxynucleotide of telomerase RNA on telomerase activity and cell apoptosis in human colon cancer

AIM:To explore the effect of antisense oligocleoxynucletide (As-ODN) of telomerase RNA on telomerase activity and cell apoptosis in human colon cancer.RESULTS:The telomerase activity in SW480 cells transfected with 1.0μmol/L of As-ODN for 2-5days, was significantly decreased in a time-dependent manner, and the cells underwent apoptosis.The missense ODN (Ms-ODN) and the control group transfected with SW480 cells did not show these changes.CONCLUSION:As-ODN can specifically inhibit the telomerase activity of SW480 cells and induce apoptosis.

Syndecan-1 and E-cadherin expression in differentiated type of early gastric cancer

AIM: To elucidate the role and alterations of syndecan-1 and E-cadherin expression in different cellular phenotypes of differentiated-type gastric cancers (DGCs), METHODS: A total of 120 DGCs at an early stage, andtheir adjacent mucosa, were studied both by immunohistochemistry. Syndecan-1 and E-cadherin were assessed by immunohistochemical staining with anti-syndecan-1 and anti-E-cadherin antibodies, respectively. Based on immunohistochemistry, DGCs and their surrounding mucosa were divided into four types: gastric type (G-type),ordinary type (O-type), complete-intestinal type (CI-type),and null type (N-type).RESULTS: Syndecan-1 expression was significantly lower in G-type cancers (29.4%) than in O-type (79.6%) and CI-type cancers (90%) (P＜0.05, respectively), but E-cadherin did not show this result. In addition, syndecan-1 expression was significantly reduced in DGCs comprised partly of poorly differentiated adenocarcinoma or signet-ring cell carcinoma, compared to DGCs demonstrating papillary and/or tubular adenocarcinoma (P＜0.05). G-type intestinal metaplasia (IM) surrounding the tumors was observed in 23.8% of G-type, 4.9% of O-type, and 6.7% of CI-type cancers (P＜0.05; G-type vs O-type). Reduction of syndecan-1 expression was significant in G-type IM (25%) compared to non-G-type IM (75%; P＜0.05).CONCLUSION: Loss of syndecan-1 plays a role in the growth of G-type cancers of DGCs at an early stage, and the reduction of syndecan-1 expression in IM surrounding the tumors may influence the growth of G-type cancer.

Synergistic antitumor effect of TRAIL and doxorubicin on colon cancer cell line SW480

AIM: TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) has been reported to specifically induce apoptosis of cancer cells although only a small percentage of cell lines were sensitive to it. Cell lines not responding to TRAIL in vitro were said to be more prone to apoptosis when TRAIL was combined with another anticancer agent.Generally, factors affecting drug-sensitivity involve many apoptosis-related proteins, including p53. The expression of wild-type p53 gene was proposed as an important premise for tumor cells responding to chemotherapy. The present study was to investigate the cell killing action of TRAIL on colon cancer cell line SW480, its synergistic effect with doxorubicin, and the possible mechanisms.METHODS: SW480 cells were cultured in the regular condition and incubated with different levels of agents.Morphologic changes in these cells after treatment were observed under phase-contrast microscope and cytotoxicity by TRAIL alone and in combination with doxorubicin was quantified by a 1-day microculture tetrazolium dye (MTT) assay. In addition, flow cytometry assay (FCM) and transmission electron microscopy were used to detect apoptosis among these cells. Variation of p53 protein level among different groups according to concentrations of agents was measured by Western blot assay.RESULTS: (1) SW480 cells were not sensitive to TRAIL,with IC50>l mg·L^1 and dose-independent cytotoxicity. (2)SW480 cells were sensitive to doxorubicin at a certain degree,with dose-dependent cytotoxicity and IC50=65.25±3.48μmol·L^-1. (3) TRAIL could synergize with doxorubicin to kill SW480 cells effectively, which was represented by the boosted killing effect of doxorubicin on theses cells. IC50 of doxorubicin against SW480 cells sharply reduced when it was combined with TRAIL. (4) Subtoxic TRAIL (100 μg·L^-1),combined with subtoxic doxorubicin (0.86 μmol·L^-1), could kill SW480 cells sufficiently. Cytotoxicity by MTT assay arrived at 80.12±2.67 %, which was significantly higher than that by TRAIL or doxorubicin alone, with P=0.006 and 0.003 respectively. This killing effect was partly due to apoptosis. It was proved by large amounts of apoptotic cells under phase-contrast microscopy, cell apoptosis rate of 76.82±1.93 % by FCM assay and typical apoptotic morphology observed through transmission electron microscopy. Increase of apoptosis after combined treatment had no relation with protein level of p53 (p>0.05).CONCLUSION: SW480 cells are not sensitive to TRAIL, but TRAIL can synergize with lower concentra^on of doxorubidn to induce apoptosis effectively. The status of p53 protein is not involved in the mechanism of synergistic apoptosis. It suggests the potential therapeutic applicability of the combination of TRAIL with doxorubidn against colon cancers.

Tracing neuronal tracts in theolfactory pathway of rat anddetecting ischemic core in arat model of focal ischemiausing manganese enhancedmagnetic resonance imaging

Manganese enhanced magnetic resonance im- aging (MRI) is a novel neuroimaging technique that can be used in vivo to trace neuronal tract and to study brain func- tions dynamically. In this study, manganese enhanced MRI was used to trace the neuronal tracts between the laminar structures of the olfactory bulb (OB) in rat and to study the so-called “calcium overload” phenomenon in a rat model of cerebral ischemia. High spatial resolution images of the OB were obtained and used to measure the transportation rate of Mn2+ among the laminar structures of the OB, which was shown to be approximately 0.2 mm/h under resting condition. In the rat focal ischemia study, it was found that the total area of brain regions with Mn2+ accumulation (representing brain regions with calcium overload) was only 55%±15% of the area of the ischemic brain regions shown by diffu- sion-weighted imaging (DWI). Manganese enhanced MRI might be more accurate than DWI in detecting the ischemic core at the early stage of experimental cerebral ischemia.