The expression of hTERT mRNA and cellular immunity in gastric cancer and precancerosis

Detection of telomerase reverse transcriptase mRNA in peripheral blood mononuclear cells of patients with liver failure

BACKGROUND

Telomerase activity is closely associated with the expression of human telomerase reverse transcriptase (hTERT) mRNA; although it can be induced in hepatocytes during liver regeneration, its dynamic change in patients with liver failure has remained unclear.

OBJECTIVES

We investigated the variation and significance of hTERT mRNA expression in peripheral blood mononuclear cells (PBMCs) of the patients with liver failure.

PATIENTS AND METHODS

In this clinical experimental study, 76 Chinese patients were enrolled in the study between 2010 and 2012. The level of PBMCs hTERT mRNA was detected by relative quantitative real-time polymerase chain reaction (RT-PCR) in the samples taken before treatment and at seven-day intervals during a 28-day treatment period. The patients were divided into survivor and non-survivor groups according to the 3-months mortality after treatment. The dynamic variation of PBMCs hTERT mRNA was analyzed and its association with prognosis was assessed by the area under the receiver-operating characteristic curve.

RESULTS

The median level of PBMCs hTERT mRNA in survivors increased with treatment time and was significantly higher than the corresponding level in non-survivors after 14 days of treatment (P < 0.001). Subgroup analyses showed that the levels of PBMCs hTERT mRNA were remarkably higher in patients with acute-on-chronic liver failure than in those with chronic liver failure (P < 0.05). In patients with the same clinical type of liver failure, the level was markedly higher in survivors than in non-survivors after 14 days of treatment (P < 0.05); however, the levels were not significantly different between subgroups with different clinical type but the same prognosis. The sensitivity and specificity of PBMCs hTERT mRNA was high in evaluating the prognosis at day 14 and became much higher at days 21 and 28 post treatment. The expression of PBMCs hTERT mRNA had high sensitivity and specificity in evaluating the prognosis as early as day 14 post treatment and was significantly superior to the prognostic value of serum alpha-fetoprotein.

CONCLUSIONS

The expression of PBMCs hTERT mRNA is closely associated with patient outcome, which indicates that hTERT mRNA in PBMCs might be useful as a prognostic biomarker of liver failure.

Gastric cancer stem cells: therapeutic targets

During the past decade, a growing body of evidence has implied that cancer stem cells (CSCs) play an important role in the development of gastric cancer (GC). The notion that CSCs give rise to GC and may be responsible for invasion, metastasis, and resistance to treatment has profound implications for anti-cancer therapy. Recent major advances in the rapidly evolving field of CSCs have opened novel exciting opportunities for developing CSC-targeted therapies. Discovery of specific markers and signaling pathways in gastric CSCs (GCSCs), with the perfecting of technologies for identification, isolation, and validation of CSCs, may provide the basis for a revolutionary cancer treatment approach based on the eradication of GCSCs. Emerging therapeutic tools based on specific properties and functions of CSCs, including activation of self-renewal signaling pathways, differences in gene expression profiles, and increased activity of telomerase or chemoresistance mechanisms, are developing in parallel with advances in nanotechnology and bioengineering. The addition of GCSC-targeted therapies to current oncological protocols and their complementary application may be the key to successfully fighting GC.

Activation of STAT3 in human gastric cancer cells via interleukin (IL)-6-type cytokine signaling correlates with clinical implications

Background

The signal transducers and activators of transcription 3 (STAT3) signaling pathway plays important roles in oncogenesis, angiogenesis, immunity, and tumor cell invasion. In the present study, we investigated the association of interleukin (IL)-6/STAT3 signaling pathway with T lymphocytes and clinical implication in patients with gastric cancer.

Methods

Seventy one patients who underwent gastrectomy due to gastric adenocarcinoma were studied. Blood samples were collected before and after surgical gastrectomy to quantify the levels of IL-6, IL-10 and VEGF using an enzyme-linked immunosorbent assay, as well as T lymphocyte subsets (CD3⁺, CD4⁺, CD8⁺, CD4⁺/CD8⁺) and natural killer (NK) cells by a flow cytometry. Furthermore, the expression of IL-6, survivin, STAT3, STAT3 phosphorylation (p-STAT3), and VEGF were determined in human gastric cancer and adjacent normal mucosa through Western blot and immunohistochemistry.

Results

Postoperative levels of IL-6, IL-10 and VEGF in serum were significantly lower than preoperative levels. Percentages of T-cell subsets and NK cells in blood were significantly increased after postoperative-week 1 as compared to preoperative group, which was further augmented at 1 month after gastrectomy. In addition, the expression of IL-6, survivin, STAT3, p-STAT3, and VEGF were increased in human gastric cancer tissues as compared to adjacent normal mucosa. Their expression was associated with TNM stage of gastric cancer. The level of STAT3 activation in clinical samples was correlated with IL-6 expression. All gastric tumor samples, which expressed p-STAT3, also expressed IL-6 with weak expression detected in adjacent normal mucosa.

Conclusion

Increased IL-6-induced activation of STAT3 was observed in neoplastic gastric tissue, which positively correlated with tumor progression. Moreover, IL-6 and STAT3 downstream signals such as IL-10 and VEGF were reduced in patients after removal of gastric cancer as compared to pre-operation. Therefore, inhibition of the IL-6/STAT3 signaling pathway may provide a new therapeutic strategy against gastric cancer.

Interferon alpha on expression of hTERT mRNA in peripheral blood mononuclear cells of patients with chronic hepatitis B

Cell division is closely related to telomerase activity (hTERT mRNA). Lower expression of lymphocitic hTERT mRNA may easily cause cell aging, which is not beneficial to maintaining a durable lymphocyte division. To date, there is no study to investigate IFNα therapy on hTERT mRNA expression in PBMCs of patients with chronic hepatitis B (CHB). We quantitatively detected hTERT mRNA from study subjects and made each hTERT mRNA normalized (NhTERT mRNA). Mean NhTERT mRNA level was lower in either CHB group, but it significantly increased in IFNα-treated group compared with CHB control group, and a longer duration of IFNα therapy could increase the level. Moreover, the mean NhTERT mRNA in subgroup with HBeAg loss was significantly higher than that in subgroup without. NhTERT mRNA was markedly correlated with CD3⁺ T lymphocyte count and CD4⁺/CD8⁺ ratio. The results showed that IFNα therapy could upregulate the expression of hTERT mRNA in PBMCs.

Expression of TERT in precancerous gastric lesions compared to gastric cancer

The objective of this study was to determine the levels of TERT mRNA and TERT protein expression in stomach precancerous lesions such as intestinal metaplasia (IM) and gastric ulcer (GU) and compare them to gastric cancer (GC). Real-time PCR was performed to detect TERT mRNA expression levels in 35 biopsies of IM, 30 of GU, and 22 of GC and their respective normal mucosas. TERT protein was detected by immunohistochemistry in 68 samples, 34 of IM, 23 of GU, and 11 of GC. Increased TERT mRNA expression levels were observed in a significant number of cases, i.e., 46% of IM, 50% of GU, and 79% of GC. The relative mean level of TERT mRNA after normalization with the β-actin reference gene and comparison with the respective adjacent normal mucosa was slightly increased in the IM and GU groups, 2.008 ± 2.605 and 2.730 ± 4.120, respectively, but high TERT mRNA expression was observed in the GC group (17.271 ± 33.852). However, there were no statistically significant differences between the three groups. TERT protein-positive immunostaining was observed in 38% of IM, 39% of GU, and 55% of GC. No association of TERT mRNA and protein expression with Helicobacter pylori infection or other clinicopathological variables was demonstrable, except for the incomplete type vs the complete type of IM. This study confirms previous data of the high expression of both TERT mRNA and protein in gastric cancer and also demonstrates this type of changed expression in IM and GU, thus suggesting that TERT expression may be deregulated in precursor lesions that participate in the early stages of gastric carcinogenesis.

Premalignant lesions in gastric cancer

Despite a plateau in incidence, gastric cancer is one of the most common cancers worldwide and causes considerable morbidity and mortality. Premalignant gastric lesions are well known risk factors for the development of intestinal-type gastric adenocarcinomas. In this multistep model of gastric carcinogenesis, Helicobacter pylori causes chronic active inflammation of the gastric mucosa, which slowly progresses through the premalignant stages of atrophic gastritis, intestinal metaplasia, and adenoma/dysplasia to gastric carcinoma. This progression is paralleled by a stepwise accumulation of multiple genetic and epigenetic abnormalities. Detection, treatment, and molecular analyses of premalignant lesions may thus provide a basis for gastric cancer prevention. This review describes an overview of current knowledge on premalignant gastric lesions. It also reviews the issue of surveillance of patients with premalignant lesions in order to improve the survival of patients with gastric cancer.

Diagnostic accuracy of human telomerase reverse transcriptase mRNA in malignant pleural effusions: A preliminary report for in situ hybridization detection

BACKGROUND

Detection of human telomerase reverse transcriptase (hTERT) mRNA by in situ hybridization (ISH) may be valuable in the diagnosis of cancer. We assessed the diagnostic performance of hTERT mRNA in cells from pleural fluid in malignant pleural effusions (PEs).

METHODS

We used a 2-step ISH with digoxin-labelled oligonucleotide probes to detect hTERT mRNA in a blinded prospective study of cells from 103 unselected pleural fluid specimens. The reference standard for malignant PEs was clinical evaluation and pleural fluid cytology, combined with pleural biopsy, other examination and follow-up as needed.

RESULTS

According to the final diagnoses, there were 41 malignant PEs, 55 benign PEs and 7 cases with uncertain etiology. When the 7 cryptogenic cases were excluded, the sensitivity and specificity of detectable hTERT mRNA for malignancy were 80% and 95%, respectively. When detection of hTERT mRNA was combined with clinical repeated pleural fluid cytology, the sensitivity and specificity were 90% and 95%, respectively.

CONCLUSIONS

Detection of hTERT mRNA in cells from pleural fluid by ISH could potentially be used in diagnosing malignant PEs as an aid. Further investigations with stricter controls and cross-validation tests will be warranted.

Telomerase: is it the future diagnostic and prognostic tool in human cancer?

A number of methods exist to detect levels of telomerase activity and the presence of telomerase subunits in a variety of tissues. As telomerase activation seems to be an important step in tumorigenesis, accurate detection of the presence and activity of the enzyme and its subunits is vital. The original method of detecting telomerase activity was developed by Kim and coworkers in 1994, and was termed the telomeric repeat amplification protocol. This assay led to a staggering increase in the number of telomerase-associated publications in scientific journals (85 publications from 1974-1994, 5063 publications from 1994-2004). A number of methods have been described to detect telomeres and to measure their length, with the standard measurement of telomere length performed using a modification of the Southern blot protocol. RNA in situ hybridization can be performed to detect levels of the RNA component of telomerase, and standard in situ hybridization and immunohistochemistry can be applied to examine expression levels and localization of the catalytic subunit of the enzyme. Reverse transcriptase PCR has also been applied to assess expression levels of the telomerase components in various tissues. This review provides a synopsis of telomeres, telomerase, telomerase and cancer, and finally, methods for the detection of telomerase in cancer.

Importance of LXR-alpha transcriptome in the modulation of innate immunity

Liver-X-Receptor alpha (LXR-alpha) that belongs to nuclear receptor/transcriptional factor family has been recognized to play crucial role in the regulation of lipid metabolism and inflammation. Consequently, the present study was addressed to explore the functional genomics of LXR-alpha within human blood immunomodulatory cells. The results of such a study, which involved LXR-alpha gene silencing through siRNA approach, revealed that: (a) the mRNA expression of genes coding for IL-8, IL-4, CX3CR1, LDLR, hTERT and c-myc was significantly elevated in response to LXR-alpha gene silencing whereas mRNA expression of genes coding for PPARs(alpha, gamma), CD36 and Dicer could not be detected; (b) the expression of Receptor C( k ) protein remained unaffected; (c) the mRNA expression of IFN-gamma gene was down regulated in LXR-alpha knockdown cells. Based upon these results we propose that LXR-alpha gene plays a crucial role in the regulation of innate immunity at the genomic level.

Pathology and molecular biology of gastric cancer

Several attempts to classify gastric cancer (GCA) have been made over the past decades. Most successful, and widely used, is the classification by Laurén, which distinguishes, by microscopical morphology alone, two main cancer pathogeneses, diffuse (DGCA) and intestinal (IGCA) subtypes, which appear clearly as dissimilar clinical and epidemiological entities. Here we review the main differences in epidemiology, histopathology, and molecular pathology of the two main subtypes of gastric carcinomas based on Laurén classification. In clinical practice, however, clinical staging, particularly in predicting the survival, still remains superior to all classifications of gastric cancer independent of cancer type. The existence of local precursor lesions or conditions of IGCA tumours, i.e. Helicobacter pylori gastritis, atrophic gastritis (AG), intestinal metaplasia (IM), adenoma, dysplasia, and intramucosal neoplasia, is firmly established. The links of DGCA with intestinal-type epithelium, AG or IM are poor, or do not exist. So far, H. pylori gastritis is the only universal precursor condition for DGCA. It implies that AG and achlorhydria are of minor significance and infrequent in the development of DGCA but are important steps in that of IGCA. Despite an increasing body of data, the overall view on molecular pathology of GCA remains fragmentary. No consistent differences in the molecular pathology of GCA subtypes to meet the Laurén classification have been established. With the exception of TP53, no gene mutation occurring regularly in both histological types of GCA has been reported. Chromosomal aberrations and loss of heterozygosity seem to be non-specific and do not follow any consistent route in the progression of GCA. Microsatellite instability is more commonly found in IGCA than in DGCA. The present epigenetic data suggest that most of the decrease (or loss) of gene expression may be explained by promoter hypermethylation which is more often found in IGCA. In DGCA specific genes such as CDH1 are more often hypermethylated. Compared with GCA, in premalignant condition lesions gene mutations and chromosomal aberrations are infrequent. Epigenetic dysregulation might also represent a major mechanism for altered gene expression in premalignant stages in gastric carcinogenesis.

Gene deregulation in gastric cancer

Despite its decreasing frequency in the Western world during recent decades, gastric cancer is still one of the leading causes of cancer-related deaths worldwide. Due to the oligosymptomatic course of early gastric cancer, most cases are diagnosed in the advanced stages of the disease. The curative potential of current standard treatment continues to be unsatisfactory, despite multimodal approaches involving surgery, chemotherapy and radiotherapy. Novel therapeutics including small molecules and monoclonal antibodies are being developed and have been partially introduced into clinical use in connection with neoplastic diseases such as chronic myeloid leukemia, non-Hodgkin's lymphoma and colorectal cancer. Thorough understanding of the changes in gene expression occurring during gastric carcinogenesis may help to develop targeted therapies and improve the treatment of this disease. Novel molecular biology techniques have generated a wealth of data on up- and down-regulation, activation and inhibition of specific pathways in gastric cancer. Here, we provide an overview of the different aspects of aberrant gene expression patterns in gastric cancer.

Expression of human telomerase reverse transcriptase gene in hepatocellular carcinoma and effect of antisense telomerase gene on apoptosis of hepatocellular cancer cell line HepG2

AIM: To examine the expression of human telomerase reverse transcriptase (hTERT) gene in human hepatocellular cancer (HCC), to investigate its relevance with the carcinogenesis, development and recurrence of HCC, and to explore the potential of antisense RNA of human telemerase (hTR) gene in the treatment of HCC.

METHODS: Immunohistochemistry was used to detect the expression of hTERT protein in 42 specimens of HCC. The relationship between hTERT expression and the clinical and pathological characteristics was analyzed. HepG2 cell line was transfected with antisense hTR expression vector (pBBS-hTR) with lipofectin. The transfected cells were cultured in vitro and then inoculated into nude mice. The cell cycle, ultrastructure and tumorigenicity of the transfected cells were examined.

RESULTS: The positive rate of hTERT gene expression in HCC was significantly higher (30/42) than that in normal liver tissues (71.4% vs 0%, P < 0.01), and the positive rates were also significantly different between HCC with pathological grades I (4/10), II(14/20) and III(12/12) (40.0% vs 70.0% vs 100%, respectively, P < 0.05). The expression of hTERT was positively correlated to the recurrence of patients (P < 0.05). The transfected cells manifested typical apoptotic morphology, and the apoptotic peak appeared before G₁ phase of cell cycle. Tumorigenesis of the transfected cells in nude mice was significantly inhibited. The survival time of nude mice inoculated with transfected cells was markedly prolonged, in comparison with that of control mice.

CONCLUSION: The aberrant expression of hTERT gene may be related to the pathogenesis and progression of HCC. The highly expressed hTERT gene may be regarded as a marker for the recurrence of HCC. The growth of HepG2 cells can be effectively inhibited and the apoptosis can be promoted by transfection of antisense telomerase RNA.

Multivariate analysis of predicting lymph node metastasis in gastric cancer

AIM: To analyze the factors influencing lymph node metastasis in gastric cancer and to screen the indicators that could predict more exactly the extent of lymph node metastasis before surgery.

METHODS: The mRNA expression of heparanase, MMP-7, VEGF-C, S100A4, hRad17, hTERT, CDH1, KAI1 and nm23H1 genes were examined in 62 gastric cancer tissues by reverse transcription polymerase chain reaction (RT-PCR). In combination with clinicopathological features, univariate and multivariate analyses were carried out in order to screen the factors affecting lymph node metastasis of gastric carcinoma.

RESULTS: All the genes above were expressed more or less in gastric cancer tissues. With regard to the positive rate, S100A4 and hTERT were the highest (both 96.8%) and CDH1 was the lowest (64.5%). Multivariate analysis with binary logistic regression showed that lymphatic invasion and heparanase mRNA expression were independent factors that judged whether there was lymph node metastasis, and the odds ratios [Exp (B)] were 21.137 (95%CI 2.115-211.211) and 9.768 (95%CI 1.582-60.300) respectively. When predicting the extent of the lymph node metastasis (the number of lymph node metastasis of no more than 6 was regarded as the fewer and lighter; no less than 7 as the more and heavier), MMP-7, hTERT and CDH1 genes mRNA expression and Lauren type of carcinoma were the independent factors (P = 0.037, 0.009, 0.021 and 0.012 respectively), Exp (B) was 8.046, 9.159, 0.087 and 10.068 respectively. The area of serosa involvement was also an important factor.

CONCLUSION: Heparanase mRNA expression and lymphatic invasion of gastric cancer tissue correlate with lymph node metastasis positively. The degree of lymph node metastasis is more serious in patients with diffusive histological type, area of serosa involvement more than 20 cm2 and MMP-7, hTERT mRNA overexpression, and CDH1 loss of expression in gastric cancer. Above examinations before surgery are indicated to arrive at an optimum treatment scheme.

Clinical efficacy and mechanism of oxaliplatin in treating human gastric carcinoma

AIM

To evaluate the therapeutic effect of oxaliplatin on human gastric carcinoma and to explore the mechanisms.

METHODS

22 cases of stage IV gastric carcinoma patients received 4-6 (mean 4.6) cycles of first line combined chemotherapy with oxaliplatin (oxaliplatin 85 mg/m², ivgtt, 1 h, d 1; leukovorin 200 mg/m², iv, gtt, 1 h, d 1-5; 5-FU 300 mg/m², iv, d 1-2; 5-FU, continuously iv, gtt, 48 h; 1 cycle/2w). Response rate, progression-free survival (PFS), total survival time, toxic side effects were evaluated. The inhibitory effect of oxaliplatin on human gastric cell line SGC-7901 was calculated by MTT and IC50 was measured. Flow cytometry and TUNEL were applied to evaluate the apoptosis of cell line induced by the drug. The expression of caspase-3 mRNA was detected by RT-PCR.

RESULTS

Total response (complete and partial) occurred in 9 (40.9%) patients. Mean PFS was 4.2 months and mean total survival time was 7.2 months. Cumulative neurotoxicity (all grade I-II), vomiting and diarrhea, myelosuppression appeared in 93.5%, 20%, 32.9% of the patients, respectively. Apoptosis index was elevated after incubating with 1 mmol/L oxaliplatin for 30 min, but without statistic significance (P>0.05), but was much higher both by flowcytometry and TUNEL with statistical significance (P<0.05) after incubating with 1 mmol/L oxaliplatin for 2 days. Caspase-3 mRNA expression was elevated in oxaliplatin treated cells and correlated with apoptosis induced by the drug.

CONCLUSION

Oxaliplatin is effective and well-tolerated on human advanced gastric carcinoma. Oxaliplatin could significantly inhibit the growth of human gastric cell line SGC-7901, inducing caspase-3 mRNA expression and cell apoptosis.

Expression of estrogen inducing gene PS2/TFF1 in gastric cancer and precancerous lesions

AIM

To determine the significance of PS2/TFF1 protein expression in chronic superficial gastritis (CSG), gastric ulcer (GU),gastric mucosal intestinal metaplasia (IM), gastric mucosal dysplasia and gastric cancer(GC).

METHODS

Pathologic specimens of 121 patients with gastric mucosal diseases and 20 healthy volunteers were immunostained for PS2/TFF1.

RESULTS

Positive PS2/TFF1 staining was seen throughout all epithelia with normal gastric mucosas, CSG, GU and in complete type of intestinal metaplasia (20/21). On the contrary, 11 of 20 incomplete type of intestinal metaplasia had positive staining (P <0.01). The expressions of PS2/TFF1 protein in CSG and GU were significantly higher than that in control group (P <0.01), while the expressions of PS2/TFF1 protein in IM,gastric mucosal dysplasia and GC were obviously lower than that in control group (P <0.01).

CONCLUSION

Our results indicate that PS2/TFF1 may play an important role in gastric mucosal protection,and loss of PS2/TFF1 expression may occur as an early event in the malignant transformation process of intestinal-type tumors.

Relationship between telomerase activity and its subunit expression and inhibitory effect of antisense hTR on pancreatic carcinoma

AIM: To directly investigate the relationship between telomerase activity and its subunit expression and the inhibitory effect of antisense hTR on pancreatic carcinogenesis.

METHODS: We examined the telomerase activity and its subunit expression by cell culture, polymerase chain reaction (PCR), PCR-silver staining, PCR-ELISA, DNA sequencing, MTT and flow cytometry methods.

RESULTS: PCR-silver staining and PCR-ELISA methods had the same specificity and sensitivity as the TRAP method. Telomerase activity was detected in the extract of the 10^th, 20^thand 30^th passages of P3 cells,while it was absent in fibroblasts. Furthermore, after the 30th generation, the proliferation period of fibroblast cells was significantly prolonged. Telomerase activity and hTERTmRNA were detected in two pancreatic carcinoma cell lines, but were found to be negative in human fibroblast cells. Telomerase activity and hTERTmRNA were tested in pancreatic carcinoma specimens of 24 cases. The telomerase activity was positive in 21 of the 24 cases (87.5%), and the hTERTmRNA in 20 cases (83.3%). In adjacent normal tissues positive rates were both 12.5%. There was a significant difference between the two groups. This indicated a significant correlation between the expression level of telomerase activity and histologic differentiation, metastasis and advanced clinical stage of pancreatic carcinoma. Our findings showed that the expressions of hTR and TP1mRNA were not correlated with the activity of telomerase but the expression of hTERTmRNA was. After treatment with PS-ODNs, telomerase activity in P₃ cells weakened and the inhibiting effect became stronger with an increase in PS-ODNs concentration. There was a significant difference between different PS-ODN groups (P < 0.05). Inhibition of telomerase activity occurred most significant with PS-ODN1.The results of the FCM test of pancreatic cancer P₃ cells showed an increase in the apoptotic rate with increasing PS-ODN1 and PS-ODN2 concentrations.

CONCLUSION: The expression of telomerase activity has a significant relationship to carcinogenesis. A strong correlation exists between telomerase activity and hTERTmRNA expression. The up-regulation of hTERTmRNA expression may play a critical role in human carcinogenesis. The expression of telomerase activity and its subunit level in pancreatic carcinoma significantly correlate with the clinical stage of pancreatic carcinoma and hence, may be helpful in its diagnosis and prognosis. The anti-hTR complementary to the template region of hTR is sufficient to inhibit P3 cell telomerase activity and cell proliferation in vitro, and can lead to a profound induction of programmed cell death.

Expression of Fas ligand and Caspase-3 contributes to formation of immune escape in gastric cancer

AIM: To study the role of Fas ligand (FasL) and Caspase-3 expression in carcinogenesis and progression of gastric cancer and molecular mechanisms of relevant immune escape.

METHODS: FasL and Caspase-3 expression was studied in adjacent epithelial cells, cancer cells and lymphocytes of primary foci, and cancer cells of metastatic foci from 113 cases of gastric cancer by streptavidin-biotin-peroxidase (S-P) immunohistochemistry. Expression of both proteins in cancer cells of primary foci was compared with clinicopathological features of gastric cancer. The relationship between FasL expression in cancer cells and Caspase-3 expression in cancer cells or infiltrating lymphocytes of primary foci was investigated.

RESULTS: Cancer cells of primary foci expressed FasL in 53.98% (61/113) of gastric cancers, more than their adjacent epithelial cells (34.51%, 39/113) (P = 0.003, χ² = 8.681), while the expression of Caspase-3 in cancer cells of primary foci was detected in 32.74% (37/113) of gastric cancers, less than in the adjacent epithelial cells (50.44%, 57/113) (P = 0.007, χ² = 7.286). Infiltrating lymphocytes of the primary foci showed positive immunoreactivity to Caspase-3 in 70.80% (80/113) of gastric cancers, more than their corresponding adjacent epithelial cells (P = 0.001, χ² = 10.635) or cancer cells of primary foci (P = 0.000, χ² = 32.767). FasL was less expressed in cancer cells of metastases (51.16%, 22/43) than in those of the corresponding primary foci (81.58%, 31/38) (P = 0.003, χ² = 9.907). Conversely, Caspase-3 was more expressed in cancer cells of metastases (58.14%, 25/43) than in those of the corresponding primary foci (34.21%, 13/38) (P = 0.031, χ² = 4.638). FasL expression was significantly correlated with tumor size (P = 0.035, rs = 0.276), invasive depth (P = 0.039, rs = 0.195), metastasis (P = 0.039, rs = 0.195), differentiation (P = 0.015, rs = 0.228) and Lauren’s classification (P = 0.038, rs = 0.196), but not with age or gender of patients, growth pattern or TNM staging of gastric cancer (P > 0.05). In contrast, Caspase-3 expression showed no correlation with any clinicopathological parameters described above in cancer cells of the primary foci (P > 0.05). Interestingly, FasL expression in primary gastric cancer cells paralleled to Caspase-3 expression in infiltrating lymphocytes of the primary foci (P = 0.016, χ² = 5.825).

CONCLUSION: Up-regulated expression of FasL and down-regulated expression of Caspase-3 in cancer cells of primary foci play an important role in gastric carcinogenesis. As an effective marker to reveal the biological behaviors, FasL is implicated in differentiation, growth, invasion and metastasis of gastric cancer by inducing apoptosis of infiltrating lymphocytes. Chemical substances derived from the primary foci and metastatic microenvironment can inhibit the growth of metastatic cells by enhancing Caspase-3 expression and diminishing FasL expression.

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Telomerase as tumor marker

Telomerase, a critical enzyme responsible for continuous cell growth, is repressed in most somatic cells except proliferating progenitor cells and activated lymphocytes, and activated in approximately 85% of human cancer tissues. Telomerase activity is a useful cancer-cell detecting marker in some types of cancers in which almost all cases show telomerase activation. In other types in which telomerase becomes upregulated according to tumor progression, it is a useful prognostic indicator. Detection of human telomerase reverse transcriptase (hTERT) mRNA or protein in various clinical samples is also applicable. However, careful attention should be paid to the false negative results due to the instability of this enzyme or hTERT mRNA and the existence of polymerase chain reaction inhibitors as well as the false-positive results due to the contamination by normal cells with telomerase activity. If these pitfalls are avoided, in situ detection of hTERT mRNA or protein will facilitate the reliability of telomerase as a tumor marker.

Tributyrin inhibits human gastric cancer SGC-7901 cell growth by inducing apoptosis and DNA synthesis arrest

AIM

To evaluate the effects of tributyrin, a pro-drug of natural butyrate and a neutral short-chain fatty acid triglyceride, on the growth inhibition of human gastric cancer SGC-7901 cell.

METHODS

Human gastric cancer SGC-7901 cells were exposed to tributyrin at 0.5, 1, 2, 5, 10 and 50 mmol/L(-1) for 24-72 h. MTT assay was applied to detect the cell proliferation. [(3)H]-TdR uptake was measured to determine DNA synthesis. Apoptotic morphology was observed by electron microscopy and Hoechst-33258 staining. Flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay were performed to detect tributyrin-triggered apoptosis. The expressions of PARP, Bcl-2 and Bax were examined by Western blot assay.

RESULTS

Tributyrin could initiate growth inhibition of SGC-7901 cell in a dose- and time-dependent manner. [(3)H]-TdR uptake by SGC-7901 cells was reduced to 33.6 % after 48 h treatment with 2 mmol/L(-1) tributyrin, compared with the control (P<0.05). Apoptotic morphology was detected by TUNEL assay. Flow cytometry revealed that tributyrin could induce apoptosis of SGC-7901 cells in dose-dependent manner. After 48 hours incubation with tributyrin at 2 mmol/L(-1), the level of Bcl-2 protein was lowered, and the level of Bax protein was increased in SGC-7901, accompanied by PARP cleavage.

CONCLUSION

Tributyrin could inhibit the growth of gastric cancer cells effectively in vitro by inhibiting DNA synthesis and inducing apoptosis, which was associated with the down-regulated Bcl-2 expression and the up-regulated Bax expression. Therefore, tributyrin might be a promising chemopreventive and chemotherapeutic agent against human gastric carcinogenesis.

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Relationship between the expression of human telomerase reverse transcriptase gene and cell cycle regulators in gastric cancer and its significance

AIM: To investigate the expression of human telomerase reverse transcriptase gene (hTRT) in gastric cancer (GC) and its relevance with cell cycle regulators including P16INK4, cyclin and P53.

METHODS: In situ hybridization (ISH) for hTRT mRNA was performed in 53 cases of gastric cancer and adjacent cancerous tissues. Immunohistochemical staining (S-P method) for hTRT protein, P16INK4, cyclinD1 and P53 was performed in 53 cases of GC and adjacent cancerous tissues.

RESULTS: Of 53 cases of GC, the expression of hTRT mRNA and hTRT protein was significantly higher than the expression of hTRT mRNA and hTRT protein in adjacent canerous tissues (P < 0.01), the positive rates of hTRTmRNA and hTRT protein were 79.2% and 88.6%. There was a stastical difference of the expression of hTRT protein among well differentiated adenocarcinoma, poorly differentiated adenocarcinoma and mucoid carcinoma. And there was a highly significant positive correlation between the expression of hTRT mRNA and hTRT protein (r = 0.625, P < 0.01). However, the expression of hTRT mRNA and its protein in GC were not related with other clinicopathological parameters including gender, age, location and size of neoplasm, invasion depth, lymph node metastasis and clinical stage. There was a significant positive correlation between the expression of hTRT mRNA and cyclinD1 protein (r = 0.350, P < 0.01). There was a significant positive correlation between the expression of cyclinD1 protein and hTRT protein (r = 0.549, P < 0.01), so was between P53 and hTRT protein (r = 0.319, P < 0.05).

CONCLUSION: The expression of hTRT gene is correlated significantly to the specific defects of cell cycle on G1/S check point ; telomerase activity may depend on cell cycle in gastric cancer and it is available to clarify the molecular mechanism of telomerase activity regulation. The expression of hTRT mRNA and hTRT protein in GC is significantly different from the expression of hTRT mRNA and hTRT protein in adjacent cancerous tissue which indicates that these targets are correlated closely to the occurrence of GC and can provide important morphologic index for diagnosis of GC.

Association between pepsinogen C gene polymorphism and genetic predisposition to gastric cancer

AIM: To identify a molecular marker for gastric cancer, and to investigate the relationship between the polymorphism of pepsinogen C (PGC) gene and the genetic predisposition to gastric cancer.

METHODS: A total of 289 cases were involved in this study. 115 cases came from Shenyang area, a low risk area of gastric cancer, including 42 unrelated controls and 73 patients with gastric cancer. 174 cases came from Zhuanghe area, a high-risk area of gastric cancer, including 113 unrelated controls, and 61 cases from gastric cancer kindred families. The polymorphism of PGC gene was detected by polymerase chain reaction (PCR) and the relation between the genetic polymorphism of PGC and gastric cancer was examined.

RESULTS: Four alleles, 310 bp (allele 1), 400 bp (allele 2), 450 bp (allele 3), and 480 bp (allele 4) were detected by PCR. The frequency of allele 1 was higher in patients with gastric cancer than that in controls. Genotypes containing homogenous allele 1 were significantly more frequent in patients with gastric cancer than that in controls (0.33, 0.14, χ² = 3.86, P < 0.05). There was no significant difference between the control group of Zhuanghe and the group of gastric cancer kindred. But the frequency of allele 1 was higher in control group of Zhuanghe area than that in control group of Shenyang area and genotypes containing homogenous allele 1 were significantly more frequent in the control group of Zhuanghe area than those in control group of Shenyang area (0.33, 0.14, χ² = 4.32, P < 0.05). In the group of gastric cancer kindred the frequency of allele 1 was significantly higher than that in control group of Shenyang area (0.5164, 0.3571, χ² = 4.47, P < 0.05). Genotypes containing homogenous allele 1 were significantly more frequent in the group of gastric cancer kindred than those in control group of Shenyang area (0.36, 0.14, χ² = 4.91, P < 0.05).

CONCLUSION: These results suggest that there is some relation between pepsinogen C gene polymorphism and gastric cancer, and the person with homogenous allele 1 predisposes to gastric cancer than those with other genotypes. Pepsinogen C gene polymorphism may be used as a genetic marker for a genetic predisposition to gastric cancer. The distribution of pepsinogen C gene polymorphism in Zhuanghe, a high-risk area of gastric cancer, is different from that in Shenyang, a low risk area of gastric cancer.

Intravenous chemotherapy for resected gastric cancer: meta-analysis of randomized controlled trials

AIM: To assess the safety and efficacy of different intravenous chemotherapeutic regimens in patients with gastric carcinomas who had undergone gastrectomy.

METHODS: A meta-analysis of all the relevant randomized controlled trials (RCTs) was performed. Language was restricted to Chinese and English. RCTs were identified from Medline and Embase (1980-2001/4), and Chinese Bio-medicine Database (1990-2001/1). Literature references were checked at the same time. We included randomized and quasi-randomized trials comparing the efficacy of intravenous chemotherapy after gastrectomy with that of surgery alone in patients with confirmed gastric carcinomas who had undergone gastrectomy. Selection criteria were: randomized or quasi-randomized trials with following-up results; Trials could be double-blind, single-blind or not blind; Chemotherapy groups were given intravenous chemotherapy after gastrectomy without neo-adjuvant chemotherapy, intraperitoneal hyperthermic perfusion, radiotherapy or chemoimmunotherapy; Controlled group included those receiving gastrectomy alone. The following data were extracted: the number of survival and death by the end of the follow-up; the different agents and doses of the intravenous chemotherapy; the baseline of the chemotherapy group and the controlled arm; the serious adverse events; the statistical consideration; cost-effectiveness analysis. The statistical analysis was performed by RevMan4.1 software which was provided by the Cochrane Collaboration. A P value of < 0.05 was considered statistically significant. Meta-analysis was done with random effects model. Heterogeneity was checked by chi-square test. Sensitivity analysis was performed by excluding the trials in which Jadad-scale was only 1 score. The result was expressed with odds ratio (OR) for the categorical variable.

RESULTS: Fourteen trials involving 4543 patients were included. Meta-analysis was done with random effects model Heterogeneity and sensitivity analysis were performed also. The effect of intravenous chemotherapy after gastrectomy was better than surgery alone (odds ratio 0.56, 95%CI 0.40-0.79). There was a significant difference between the two groups by u-test (P = 0.0008). Sensitivity analysis revealed the same difference (odds ratio 0.81, 95%CI 0.70-0.94). Of fourteen trials, only three studies were of high quality according to the Jadad-scale (with three score). There was one meta-analysis trial and the others, about ten trials, were of low quality. There was no trial which mentioned sample-size calculation, allocation concealment, intention-to-treat analysis. Most of the trials didn’t describe the blind-procedure. There were five trials which detailed the side-effects according to the toxicity grade by WHO standard. The side-effects halting treatment were haematologic and biochemical toxicity, debilitating nausea and vomiting. There were two patients died of chemotherapy toxicity.

CONCLUSION: Based on the review, intravenous chemotherapy after gastrectomy may have positive treatment effect on gastric cancer. However, the evidence is not strong because of the general low methodologic quality of the RCTs. Therefore, we can’t make the conclusion that intravenous chemotherapy after gastrectomy may have better treatment effect on gastric cancer than that of surgery alone. Rigorously designed, randomised, double-blind, placebo-controlled trials are required.