Apoptosis-inducing effect of recombinant Caspase-3 expressed by constructed eukaryotic vector on gastric cancer cell line SGC7901

Eukaryotic expression vectors bearing genes encoding cytotoxic proteins for cancer gene therapy

Cancer gene therapy is a promising direction for the treatment of cancer patients. A primary goal of all cancer therapies is to selectively target and kill tumour cells. Such therapies are administered via different approaches, including both viral and non-viral delivery; however, both methods have advantages and disadvantages. Transcriptional targeting enables genes encoding toxic proteins to be expressed directly in cancer cells. Numerous vectors have been created with the purpose of killing cancer cells, and some have successfully suppressed malignant tumours. Data concerning the function of vectors bearing genes that encode cytotoxic proteins under the control of different promoters, including tissue/tumour specific and constitutive promoters, is summarised here. This review focuses on vectors that bear genes encoding diphtheria toxin, Pseudomonas exotoxin A, caspases, gef, streptolysin, and melittin. Data describing the efficacy of such vectors have been summarised. Notably, there are vectors that killed cancer cell lines originating from the same type of cancer with differential efficiency. Thus, there is differential inhibition of cancer cell growth dependent on the cell line. In this review, the constructs employing genes whose expression induces cell death and the efficiency with which they suppress cancer cell growth will be summarised.

Adenoviral gene therapy in gastric cancer: A review

Gastric cancer is one of the most common malignancies worldwide. With current therapeutic approaches the prognosis of gastric cancer is very poor, as gastric cancer accounts for the second most common cause of death in cancer related deaths. Gastric cancer like almost all other cancers has a molecular genetic basis which relies on disruption in normal cellular regulatory mechanisms regarding cell growth, apoptosis and cell division. Thus novel therapeutic approaches such as gene therapy promise to become the alternative choice of treatment in gastric cancer. In gene therapy, suicide genes, tumor suppressor genes and anti-angiogenesis genes among many others are introduced to cancer cells via vectors. Some of the vectors widely used in gene therapy are Adenoviral vectors. This review provides an update of the new developments in adenoviral cancer gene therapy including strategies for inducing apoptosis, inhibiting metastasis and targeting the cancer cells.

Gene therapy for gastric cancer: Is it promising?

Gastric cancer is one of the most common tumors worldwide. The therapeutic outcome of conventional therapies is inefficient. Thus, new therapeutic strategies are urgently needed. Gene therapy is a promising molecular alternative in the treatment of gastric cancer, including the replacement of defective tumor suppressor genes, the inactivation of oncogenes, the introduction of suicide genes, genetic immunotherapy, anti-angiogenetic gene therapy, and virotherapy. Improved molecular biological techniques and a better understanding of gastric carcinogenesis have allowed us to validate a variety of genes as molecular targets for gene therapy. This review provides an update of the new developments in cancer gene therapy, new principles, techniques, strategies and vector systems, and shows how they may be applied in the treatment of gastric cancer.

Significance of survivin and caspase-3 protein expression in gastric precancerous lesions and gastric cancer tissue

AIM: To detect the expression survivin and caspase-3 in the tissues of gastric cancer and precancerous lesion, and to explore their roles in the carcinogenesis gastric cancer.

METHODS: The expression of survivin and caspase-3 protein were detected by Envision immunohistochemistry in 131 cases of paraffin-embedded specimens from different gastric mucosa, including 44 cases of chronic gastritis, 31 cases of intestinal metaplasia, 40 cases of dysplasia and 16 cases of gastric cancer.

RESULTS: The positive rates of survivin expression in chronic gastritis, intestinal metaplasia, dysplasia and gastric cancer were 4.5%(2/44), 51.6%(15/31), 100.0%(40/40) and 93.8%(15/16) respectively. The positive rates of survivin protein in gastric cancer and dysplasia were significantly higher than that in intestinal metaplasia(P<0.05). The level of caspase-3 expression in positive survivin groups was significantly lower than in negative survivin group(23.1% vs 66.7%, P<0.05).

CONCLUSION: The positive rate of survivin protein in gastric cancer is similar to that in dysplasia, and higher than that in intestinal metaplasia. Survivin may promote the progression of gastric cancer by inhibiting the expression of caspase-3.

Protein expression of fragile histidine triad and non-metastasis 23-H1 and their clinicopathological significance in gastric cancer

AIM: To explore the expression of fragile histidine triad (FHIT) and non-metastasis 23-H₁ (nm23-H₁) and to investigate their relations with clinicopathological behaviors of gastric cancer.

METHODS: PV9000 two-step immunohistochemical method was employed to detect the expression of FHIT and nm23-H₁ in 98 cases of gastric cancer.

RESULTS: The positive rates of FHIT and nm23-H₁ expression were 38.8% (38/98) and 33% (28/87) respectively. The FHIT expression related to the histological classification, Lauren classification and lymph node metastasis of gastric cancer (P < 0.05). The positive rate of FHIT protein expression became higher with the development of gastric cancer, but there was no significance (P > 0.05). The nm23-H₁ expression was negatively related to clinical staging and lymph node metastasis (P < 0.05).

CONCLUSION: FHIT may be an important candidate of tumor suppressor gene in gastric cancer. The expression of FHIT and nm23-H₁ protein has close relations with lymph node metastasis in gastric cancer, and they may work synergistically and can be important markers for predicting metastasis and evaluating prognosis of gastric cancer.

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Effects of BAK gene over-expression on apoptosis in gastric cancer cells and its molecular mechanisms

AIM: To explore the apoptosis-inducing effects of extrinsic BAK gene transfer and its over-expression on gastric cancer cells and its molecular mechanisms.

METHODS: The eukaryotic expression for BAK gene was constructed and transferred into gastric cancer MKN-45 cell line. After being transferred for 1 to 5 d, cellular BAK gene expression was detected by RT-PCR and Western blotting methods. The growth activities of cancer cells were detected by cell count and MTT colorimetry. Cell cycle changes were assayed by flow cytometry. Cellular apoptosis was assayed by electronic microscopy and in situ terminally labeled transferase technique (TUNEL). Cellular caspase-3 activities were observed by colorimetric method.

RESULTS: After being transferred for 1 to 5 d, cellular BAK mRNA and protein expression levels were significantly increased (P < 0.01). In vitro growth of gastric cancer cells was inhibited by 11.6-35.3% (P < 0.01). The cellular proliferation activities were decreased by 10.2-32.4% (P < 0.01), with cell cycle being blocked at G0/G1 phase. Partial cancer cells presented the characteristic morphological changes of apoptosis, with the apoptotic rates being 21.4% (P < 0.01). The cellular caspase-3 activities were enhanced by 4.45 times (P < 0.01).

CONCLUSION: Transfection of extrinsic BAK gene, resulting in its over-expression, can significantly induce apoptosis of gastric cancer MKN-45 cells through activating caspase-3, which is a potential strategy for gene therapy of gastric cancer.

Alterations of mtDNA copy number in gastric carcinoma

AIM: To explore the relationship between mitochondrial DNA (mtDNA) and gastric cancer by comparing the difference of mtDNA copy number in gastric cancers and paracancerous tissues.

METHODS: Hypervariable reigon (HV)₁ and HV₂ of mitochondrial D-loop region from 20 cases of gastric cancer and 20 paracancerous tissues were amplified by PCR; meantime b-actin was served as a quantitative standard marker, followed by polyacrylamide gel electrophoresis (PAGE) and silver staining, in which the difference of mtDNA copy number was compared between gastric cancers and paracancerous tissues.

RESULTS: There existed significantly quantitative difference in HV₁, HV₂ (standardized with b-actin) between gastric cancers and paracancerous tissues (P < 0.01). mtDNA copy number was associated with important enzymes in nucleus such as AKP, cAMP-PDE and cGMP-PDE (P < 0.05), although not with tumor histological type and invasive depth (P > 0.05).

CONCLUSION: The occurrence of gastric cancer is closely associated with decreased mtDNA copy number, which may be a new tumor marker.

Caspase-3 inhibits the growth of breast cancer cells independent of protease activity

In this study, the MCF-7 breast cancer cells that lack caspase-3 were transfected with a wild type (WT) or mutant caspase-3 cDNA. Expression of the WT, but not of the mutant, caspase-3 was associated with increased caspase activity and susceptibility to staurosporine (STS)-induced apoptosis. Both derivatives displayed inhibition of cell growth compared with vector control cells. Growth inhibition was associated with increased expression of the cyclin dependent kinase (CDK) inhibitor p27Kip1 in the WT, but not in the mutant caspase-3 expressing cells. Cyclin D1 expression level was not affected by caspase-3 expression. Phosphorylation of the Akt protein was decreased in both WT and mutant caspase transfected cells, although Akt expression level remained unchanged. These results suggest that caspase-3 might have biological functions independent of its protease activity and that its loss might contribute to tumor development by increasing the growth potential of cancer cells.