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Decreased expression of the mannose 6-phosphate/insulin-like growth factor-II receptor promotes growth of human breast cancer cells.

Chen Z, Ge Y, Landman N, Kang JX - BMC Cancer (2002)

Bottom Line: Our results showed that infection of MCF-7 cells with the adenovirus carrying a ribozyme targeted against the M6P/IGF2R mRNA dramatically reduced the level of transcripts and the functional activity of M6P/IGF2R in these cells.Furthermore, decreased expression of M6P/IGF2R enhanced IGF-II-induced proliferation and reduced cell susceptibility to TNF-induced apoptosis.This study also demonstrates that adenoviral delivery of the ribozyme provides a useful tool for investigating the role of M6P/IGF2R in regulation of cell growth.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston 02114, USA. j8018@yahoo.com

ABSTRACT

Background: Loss or mutation of the mannose 6-phosphate/insulin-like growth factor-II receptor (M6P/IGF2R) has been found in breast cancer. However, whether or not decreased levels of functional M6P/IGF2R directly contribute to the process of carcinogenesis needs to be further verified by functional studies.

Methods: In this study, using viral and ribozyme strategies we reduced the expression of M6P/IGF2R in human breast cancer cells and then examined the effect on growth and apoptosis of these cells.

Results: Our results showed that infection of MCF-7 cells with the adenovirus carrying a ribozyme targeted against the M6P/IGF2R mRNA dramatically reduced the level of transcripts and the functional activity of M6P/IGF2R in these cells. Accordingly, cells treated with a ribozyme exhibited a higher growth rate and a lower apoptotic index than control cells (infected with a control vector). Furthermore, decreased expression of M6P/IGF2R enhanced IGF-II-induced proliferation and reduced cell susceptibility to TNF-induced apoptosis.

Conclusions: These results suggest that M6P/IGF2R functions as a growth suppressor and its loss or mutation may contribute to development and progression of cancer. This study also demonstrates that adenoviral delivery of the ribozyme provides a useful tool for investigating the role of M6P/IGF2R in regulation of cell growth.

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Effects of the IGF2R ribozyme on the apoptosis induced by TNF in MCF-7 cells. Cells were infected with Ad.GFP (control, left panels) or Ad.GFP/Rz-IGF2R (right panels). 72 hrs post infection, cells were treated with TNF for one day and then cell death was examined using a fluorescence microscope. Upper panels: Cells were stained with Hoechst dye for nuclei and observed under 480 nm blue-fluorescent light. The bright blue spots are the nuclei of apoptotic cells. Lower panels: Cells were stained with Propidium Iodide dye for nuclei and observed under 565 nm red-fluorescent light. The red spots are the nuclei of dead cells.
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Figure 6: Effects of the IGF2R ribozyme on the apoptosis induced by TNF in MCF-7 cells. Cells were infected with Ad.GFP (control, left panels) or Ad.GFP/Rz-IGF2R (right panels). 72 hrs post infection, cells were treated with TNF for one day and then cell death was examined using a fluorescence microscope. Upper panels: Cells were stained with Hoechst dye for nuclei and observed under 480 nm blue-fluorescent light. The bright blue spots are the nuclei of apoptotic cells. Lower panels: Cells were stained with Propidium Iodide dye for nuclei and observed under 565 nm red-fluorescent light. The red spots are the nuclei of dead cells.

Mentions: We examined the effects of ribozyme expression on apoptosis of cultured MCF-7 cells. After treatment with TNF, as shown in Fig. 6, a large number of control cells underwent apoptosis, as indicated by morphological changes (small round shape) and bright blue nuclear staining. There were significantly more apoptotic cells in control cultures than in cultures expressing the Ad-GFP/IGF2R-Rz. Accordingly, the number of viable cells, as measured by MTT analysis, in cultures infected with Ad-GFP/IGF2R-Rz was significantly (about 40%) higher than in cultures infected with Ad-GFP (Fig. 7A). The number of apoptotic cells, as measured by the cell death ELISA assay, in cultures infected with Ad-GFP/IGF2R-Rz was significantly (about 36%) lower than in cultures infected with Ad-GFP (Fig. 7B). These results are consistent with the hypothesis that decreasing M6P/IGF2R expression by ribozyme treatment can reduce cell apoptosis.


Decreased expression of the mannose 6-phosphate/insulin-like growth factor-II receptor promotes growth of human breast cancer cells.

Chen Z, Ge Y, Landman N, Kang JX - BMC Cancer (2002)

Effects of the IGF2R ribozyme on the apoptosis induced by TNF in MCF-7 cells. Cells were infected with Ad.GFP (control, left panels) or Ad.GFP/Rz-IGF2R (right panels). 72 hrs post infection, cells were treated with TNF for one day and then cell death was examined using a fluorescence microscope. Upper panels: Cells were stained with Hoechst dye for nuclei and observed under 480 nm blue-fluorescent light. The bright blue spots are the nuclei of apoptotic cells. Lower panels: Cells were stained with Propidium Iodide dye for nuclei and observed under 565 nm red-fluorescent light. The red spots are the nuclei of dead cells.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC117795&req=5

Figure 6: Effects of the IGF2R ribozyme on the apoptosis induced by TNF in MCF-7 cells. Cells were infected with Ad.GFP (control, left panels) or Ad.GFP/Rz-IGF2R (right panels). 72 hrs post infection, cells were treated with TNF for one day and then cell death was examined using a fluorescence microscope. Upper panels: Cells were stained with Hoechst dye for nuclei and observed under 480 nm blue-fluorescent light. The bright blue spots are the nuclei of apoptotic cells. Lower panels: Cells were stained with Propidium Iodide dye for nuclei and observed under 565 nm red-fluorescent light. The red spots are the nuclei of dead cells.
Mentions: We examined the effects of ribozyme expression on apoptosis of cultured MCF-7 cells. After treatment with TNF, as shown in Fig. 6, a large number of control cells underwent apoptosis, as indicated by morphological changes (small round shape) and bright blue nuclear staining. There were significantly more apoptotic cells in control cultures than in cultures expressing the Ad-GFP/IGF2R-Rz. Accordingly, the number of viable cells, as measured by MTT analysis, in cultures infected with Ad-GFP/IGF2R-Rz was significantly (about 40%) higher than in cultures infected with Ad-GFP (Fig. 7A). The number of apoptotic cells, as measured by the cell death ELISA assay, in cultures infected with Ad-GFP/IGF2R-Rz was significantly (about 36%) lower than in cultures infected with Ad-GFP (Fig. 7B). These results are consistent with the hypothesis that decreasing M6P/IGF2R expression by ribozyme treatment can reduce cell apoptosis.

Bottom Line: Our results showed that infection of MCF-7 cells with the adenovirus carrying a ribozyme targeted against the M6P/IGF2R mRNA dramatically reduced the level of transcripts and the functional activity of M6P/IGF2R in these cells.Furthermore, decreased expression of M6P/IGF2R enhanced IGF-II-induced proliferation and reduced cell susceptibility to TNF-induced apoptosis.This study also demonstrates that adenoviral delivery of the ribozyme provides a useful tool for investigating the role of M6P/IGF2R in regulation of cell growth.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston 02114, USA. j8018@yahoo.com

ABSTRACT

Background: Loss or mutation of the mannose 6-phosphate/insulin-like growth factor-II receptor (M6P/IGF2R) has been found in breast cancer. However, whether or not decreased levels of functional M6P/IGF2R directly contribute to the process of carcinogenesis needs to be further verified by functional studies.

Methods: In this study, using viral and ribozyme strategies we reduced the expression of M6P/IGF2R in human breast cancer cells and then examined the effect on growth and apoptosis of these cells.

Results: Our results showed that infection of MCF-7 cells with the adenovirus carrying a ribozyme targeted against the M6P/IGF2R mRNA dramatically reduced the level of transcripts and the functional activity of M6P/IGF2R in these cells. Accordingly, cells treated with a ribozyme exhibited a higher growth rate and a lower apoptotic index than control cells (infected with a control vector). Furthermore, decreased expression of M6P/IGF2R enhanced IGF-II-induced proliferation and reduced cell susceptibility to TNF-induced apoptosis.

Conclusions: These results suggest that M6P/IGF2R functions as a growth suppressor and its loss or mutation may contribute to development and progression of cancer. This study also demonstrates that adenoviral delivery of the ribozyme provides a useful tool for investigating the role of M6P/IGF2R in regulation of cell growth.

Show MeSH
Related in: MedlinePlus