Targeting bcl-2 by triplex-forming oligonucleotide--a promising carrier for gene-radiotherapy

Triplex forming oligonucleotides (TFO) provide a promising tool for gene therapy. DNA damaging agents have been successfully coupled to TFOs and induce site-directed DNA damages. Here, we attempted to apply this antigen strategy using a TFO incorporated with a Conversion-electron-emitter, (99m)technetium, to target bcl-2 gene, the prototypical inhibitor of apoptosis. In the bcl-2 promoter region, we found two TFO binding sites which bind corresponding TFOs with very high specificity and affinity. Both partially and completely phosphorothioated TFOs form stable triplexes and significantly inhibit gene transcription in vitro. We also found that purine motif TFO with a thymidine opposite a thymidine interruption at the polypurine strand can form a stable triplex. In addition, (99m)technetium-conjugated TFOs were found to form a stable triplex and to inhibit bcl-2 gene transcription in vitro. Our results suggest a promising application of this triplex-forming oligonucleotide based Conversion-electron-emitter mediated gene radiotherapy in diseases related to bcl-2 overexpression.

Differential expression of apoptosis receptors on diffuse and intestinal type stomach carcinoma

BACKGROUND

Intestinal and diffuse adenocarcinomas of the stomach differ in phenotypic properties, morphology, and growth behavior. Apoptosis (programmed cell death) is induced via specific cell-surface receptors (SC-1, Fas/APO-1/CD95) and coregulated by intracellular molecules (bcl-2, p53, etc.); the success of apoptotic processes is dependent on the expression of these signals. Differences in the expression of specific apoptosis receptors and intracellular-related signals might help to explain the molecular pathogenesis of these two types of stomach adenocarcinoma.

METHODS

Immunohistochemical studies were performed on frozen sections of tumor tissue using human monoclonal antibody SC-1 and murine monoclonal antibodies Fas and p53, followed by peroxidase-coupled second antibodies. To determine binding of SC-1 and Fas antibodies to stomach carcinoma cells on the molecular level, Western blot analysis was performed with cell extract preparations from stomach carcinoma cells. To investigate functional apoptotic activity, MTT assays were performed with SC-1 and Fas antibodies on stomach carcinoma cells.

RESULTS

On frozen sections intestinal type stomach carcinoma cells demonstrate little or no expression of SC-1 and Fas receptors (4 of 17 and 1 of 17, respectively). Diffuse type stomach carcinoma cells show just the opposite: greater than 50% express SC-1 and Fas at a high level (15 of 30 and 22 of 30, respectively). Normal stomach mucosa is negative with both antibodies. Expression of p53 is positively correlated with intestinal type carcinomas (11 of 17) but not with diffuse type (5 of 30). In functional studies MTT assay) the SC-1 and Fas antibodies react with stomach carcinoma by inducing apoptosis and inhibiting growth. On Western blot analysis of extracts from stomach carcinoma cells, SC-1 detects a protein of 50 kilodalton (kD) and Fas proteins of approximately 30, 45, and 60 kD.

CONCLUSIONS

These data indicate that gastric carcinoma cells of the intestinal and diffuse type differ in their expression of the apoptotic receptors SC-1 and Fas and the tumor suppressor gene product p53. These new data on phenotypic differences support the hypothesis that these two types of stomach carcinoma do not only differ in morphology, growth pattern, and risk factors but also in genetic pathways.

Differential expression of apoptosis receptors on diffuse and intestinal type stomach carcinoma

BACKGROUND

Intestinal and diffuse adenocarcinomas of the stomach differ in phenotypic properties, morphology, and growth behavior. Apoptosis (programmed cell death) is induced via specific cell-surface receptors (SC-1, Fas/APO-1/CD95) and coregulated by intracellular molecules (bcl-2, p53, etc.); the success of apoptotic processes is dependent on the expression of these signals. Differences in the expression of specific apoptosis receptors and intracellular-related signals might help to explain the molecular pathogenesis of these two types of stomach adenocarcinoma.

METHODS

Immunohistochemical studies were performed on frozen sections of tumor tissue using human monoclonal antibody SC-1 and murine monoclonal antibodies Fas and p53, followed by peroxidase-coupled second antibodies. To determine binding of SC-1 and Fas antibodies to stomach carcinoma cells on the molecular level, Western blot analysis was performed with cell extract preparations from stomach carcinoma cells. To investigate functional apoptotic activity, MTT assays were performed with SC-1 and Fas antibodies on stomach carcinoma cells.

RESULTS

On frozen sections intestinal type stomach carcinoma cells demonstrate little or no expression of SC-1 and Fas receptors (4 of 17 and 1 of 17, respectively). Diffuse type stomach carcinoma cells show just the opposite: greater than 50% express SC-1 and Fas at a high level (15 of 30 and 22 of 30, respectively). Normal stomach mucosa is negative with both antibodies. Expression of p53 is positively correlated with intestinal type carcinomas (11 of 17) but not with diffuse type (5 of 30). In functional studies MTT assay) the SC-1 and Fas antibodies react with stomach carcinoma by inducing apoptosis and inhibiting growth. On Western blot analysis of extracts from stomach carcinoma cells, SC-1 detects a protein of 50 kilodalton (kD) and Fas proteins of approximately 30, 45, and 60 kD.

CONCLUSIONS

These data indicate that gastric carcinoma cells of the intestinal and diffuse type differ in their expression of the apoptotic receptors SC-1 and Fas and the tumor suppressor gene product p53. These new data on phenotypic differences support the hypothesis that these two types of stomach carcinoma do not only differ in morphology, growth pattern, and risk factors but also in genetic pathways.

Differential expression of apoptosis receptors on diffuse and intestinal type stomach carcinoma

BACKGROUND

Intestinal and diffuse adenocarcinomas of the stomach differ in phenotypic properties, morphology, and growth behavior. Apoptosis (programmed cell death) is induced via specific cell-surface receptors (SC-1, Fas/APO-1/CD95) and coregulated by intracellular molecules (bcl-2, p53, etc.); the success of apoptotic processes is dependent on the expression of these signals. Differences in the expression of specific apoptosis receptors and intracellular-related signals might help to explain the molecular pathogenesis of these two types of stomach adenocarcinoma.

METHODS

Immunohistochemical studies were performed on frozen sections of tumor tissue using human monoclonal antibody SC-1 and murine monoclonal antibodies Fas and p53, followed by peroxidase-coupled second antibodies. To determine binding of SC-1 and Fas antibodies to stomach carcinoma cells on the molecular level, Western blot analysis was performed with cell extract preparations from stomach carcinoma cells. To investigate functional apoptotic activity, MTT assays were performed with SC-1 and Fas antibodies on stomach carcinoma cells.

RESULTS

On frozen sections intestinal type stomach carcinoma cells demonstrate little or no expression of SC-1 and Fas receptors (4 of 17 and 1 of 17, respectively). Diffuse type stomach carcinoma cells show just the opposite: greater than 50% express SC-1 and Fas at a high level (15 of 30 and 22 of 30, respectively). Normal stomach mucosa is negative with both antibodies. Expression of p53 is positively correlated with intestinal type carcinomas (11 of 17) but not with diffuse type (5 of 30). In functional studies MTT assay) the SC-1 and Fas antibodies react with stomach carcinoma by inducing apoptosis and inhibiting growth. On Western blot analysis of extracts from stomach carcinoma cells, SC-1 detects a protein of 50 kilodalton (kD) and Fas proteins of approximately 30, 45, and 60 kD.

CONCLUSIONS

These data indicate that gastric carcinoma cells of the intestinal and diffuse type differ in their expression of the apoptotic receptors SC-1 and Fas and the tumor suppressor gene product p53. These new data on phenotypic differences support the hypothesis that these two types of stomach carcinoma do not only differ in morphology, growth pattern, and risk factors but also in genetic pathways.

Apoptosis of stomach carcinoma cells induced by a human monoclonal antibody

BACKGROUND

Although stomach carcinoma is estimated to be one of the most frequent cancers worldwide, still little is known about the immunity of patients with stomach cancer. Humoral tumor immunity has been studied by isolating B cells of patients with cancer to characterize the activity of such antibodies on tumor cells. Apoptosis, programmed cell death, explains the suicide of cells by fragmentation of DNA, cell shrinkage and dilation of endoplasmatic reticulum, followed by cell fragmentation and formation of membrane vesicles called apoptotic bodies. Apoptosis serves to remove unwanted, damaged, or dangerous, e.g., precancerous cells.

METHODS

The human monoclonal antibody SC-1 was isolated from a patient with a signet ring cell carcinoma of the stomach by fusion of spleen lymphocytes to the heteromyeloma SPM4-0. The antibody was tested for growth-inhibiting effects in vitro in soft agar assays, in 3-H thymidine uptake experiments, and in a mitochondrial enzymatic activity assay. In vivo intraperitoneal tumor growth was investigated in nu-nu mice.

RESULTS

The immunoglobulin M (lambda) antibody identifies a molecule with a molecular weight of approximately 49 kilodaltons in stomach carcinoma cells. No reactivity was observed with carcinomas of other origins, melanomas, lymphomas, or normal tissue. When tested in vitro, the antibody inhibited tumor cell growth in cell culture and soft agar. In vivo growth of stomach carcinoma cells in nu-nu mice was reduced when the antibody was injected after the tumor cells. Ultrastructural and functional studies revealed that the SC-1 antibody induced apoptosis of tumor cells.

CONCLUSION

The human monoclonal antibody SC-1 described here inhibited growth of stomach carcinoma cells in vitro and in vivo by inducing apoptosis, and may, therefore, be valuable for treating patients with stomach carcinoma.

Apoptosis of stomach carcinoma cells induced by a human monoclonal antibody

BACKGROUND

Although stomach carcinoma is estimated to be one of the most frequent cancers worldwide, still little is known about the immunity of patients with stomach cancer. Humoral tumor immunity has been studied by isolating B cells of patients with cancer to characterize the activity of such antibodies on tumor cells. Apoptosis, programmed cell death, explains the suicide of cells by fragmentation of DNA, cell shrinkage and dilation of endoplasmatic reticulum, followed by cell fragmentation and formation of membrane vesicles called apoptotic bodies. Apoptosis serves to remove unwanted, damaged, or dangerous, e.g., precancerous cells.

METHODS

The human monoclonal antibody SC-1 was isolated from a patient with a signet ring cell carcinoma of the stomach by fusion of spleen lymphocytes to the heteromyeloma SPM4-0. The antibody was tested for growth-inhibiting effects in vitro in soft agar assays, in 3-H thymidine uptake experiments, and in a mitochondrial enzymatic activity assay. In vivo intraperitoneal tumor growth was investigated in nu-nu mice.

RESULTS

The immunoglobulin M (lambda) antibody identifies a molecule with a molecular weight of approximately 49 kilodaltons in stomach carcinoma cells. No reactivity was observed with carcinomas of other origins, melanomas, lymphomas, or normal tissue. When tested in vitro, the antibody inhibited tumor cell growth in cell culture and soft agar. In vivo growth of stomach carcinoma cells in nu-nu mice was reduced when the antibody was injected after the tumor cells. Ultrastructural and functional studies revealed that the SC-1 antibody induced apoptosis of tumor cells.

CONCLUSION

The human monoclonal antibody SC-1 described here inhibited growth of stomach carcinoma cells in vitro and in vivo by inducing apoptosis, and may, therefore, be valuable for treating patients with stomach carcinoma.

Human monoclonal antibodies from stomach carcinoma patients react with Helicobacter pylori and stimulate stomach cancer cells in vitro

BACKGROUND

In recent studies, an increased incidence of gastric adenocarcinomas was observed in patients with Helicobacter pylori infection. However, the extent to which this coincidence is caused by immunologic mechanisms is unknown.

METHODS

Two human monoclonal antibodies (MoAbs) from patients with stomach carcinoma and H. pylori-associated gastritis were isolated and established by fusion of spleen cells with the heteromyeloma HAB-1. The reactivity of these human MoAbs was investigated in functional adhesion assays and on Western blots of tissue, tumor cell, and bacterial extracts. Their stimulation and proliferation were tested by the MTT test and 3-H-thymidine incorporation tests.

RESULTS

The two monoclonal immunoglobulin-M antibodies, 103/51 and 105/79, inhibited adhesion of tumor cells. On bacterial extracts antibody 103/51 identified protein bands of 55 kilodaltons (kd) and 80 kd, and in tumor cell extracts, a specific protein of approximately about 110 kd and 140 kd. Antibody 105/79 identified a 55 kd protein in bacterial extracts and a 110 kd protein in tumor extracts. In addition, in the 3-H-thymidine incorporation and MTT assay the antibodies showed a stimulatory and growth-enhancing effect on tumor cells in vitro. A similar activity was observed in sera from patients with gastric carcinoma, indicating a physiologic role of such antibodies in vivo.

CONCLUSION

The human monoclonal antibodies described here react with H. pylori and cross-react with and stimulate gastric carcinoma cells. It is possible that the production of these antibodies is primarily stimulated by bacterial antigens which cause chronic gastritis and that they might be indirectly responsible for the recently described higher incidence of gastric cancer because of the simultaneous reaction and stimulation of tumor cells they cause.