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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 ribozyme on the proliferation of MCF-7 cells. Cells were infected with Ad.GFP/IGF2R-Rz or Ad.GFP treated with or without IGF-II and then analyzed by MTT assay. Each point, the mean of three separate experiments (n = 3; *, p < 0.05; **, p < 0.01 versus control).
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Figure 5: Effects of the ribozyme on the proliferation of MCF-7 cells. Cells were infected with Ad.GFP/IGF2R-Rz or Ad.GFP treated with or without IGF-II and then analyzed by MTT assay. Each point, the mean of three separate experiments (n = 3; *, p < 0.05; **, p < 0.01 versus control).

Mentions: We examined the effects of ribozyme-induced M6P/IGF2R down-regulation on the growth of cultured MCF-7 cells. We did not observe any difference in cell growth between GFP-only infected and non-infected cells (data not shown). Thus, all subsequent experiments were performed using GFP-only infected cells as control. Assessment of cell proliferative activity by MTT assay and counting of viable cells (data not shown) indicated that the number of MCF-7 cells in ribozyme-expressing cultures was significantly higher than that in control cultures (Fig. 5). These differences in growth pattern and cell number were even more significant when the cultures were treated with exogenous IGF-II (50 ng/ml, supplemented to culture medium) (Fig. 5). These results suggest that decreasing M6P/IGF2R expression by the ribozyme can enhance proliferation of human breast cancer MCF-7 cells via an IGF-II-related mechanism.


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 ribozyme on the proliferation of MCF-7 cells. Cells were infected with Ad.GFP/IGF2R-Rz or Ad.GFP treated with or without IGF-II and then analyzed by MTT assay. Each point, the mean of three separate experiments (n = 3; *, p < 0.05; **, p < 0.01 versus control).
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Related In: Results  -  Collection

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

Figure 5: Effects of the ribozyme on the proliferation of MCF-7 cells. Cells were infected with Ad.GFP/IGF2R-Rz or Ad.GFP treated with or without IGF-II and then analyzed by MTT assay. Each point, the mean of three separate experiments (n = 3; *, p < 0.05; **, p < 0.01 versus control).
Mentions: We examined the effects of ribozyme-induced M6P/IGF2R down-regulation on the growth of cultured MCF-7 cells. We did not observe any difference in cell growth between GFP-only infected and non-infected cells (data not shown). Thus, all subsequent experiments were performed using GFP-only infected cells as control. Assessment of cell proliferative activity by MTT assay and counting of viable cells (data not shown) indicated that the number of MCF-7 cells in ribozyme-expressing cultures was significantly higher than that in control cultures (Fig. 5). These differences in growth pattern and cell number were even more significant when the cultures were treated with exogenous IGF-II (50 ng/ml, supplemented to culture medium) (Fig. 5). These results suggest that decreasing M6P/IGF2R expression by the ribozyme can enhance proliferation of human breast cancer MCF-7 cells via an IGF-II-related mechanism.

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