Related Experiment Videos
Plasmid expression of a peptide that selectively blocks oncogenic ras-p21-induced oocyte maturation
1Department of Biology Chemistry, Long Island University, Brooklyn, NY 11201, USA.
Purpose:
We have previously found that a synthetic peptide corresponding to ras-p21 residues 96 110 (PNC2) selectively blocks oncogenic (Val 12-containing) ras-p21 protein-induced oocyte maturation. With a view to introducing this peptide into ras-transformed human cells to inhibit their proliferation, we synthesized an inducible plasmid that expressed this peptide sequence. Our purpose was to test this expression system in oocytes to determine if it was capable of causing selective inhibition of oncogenic ras-p21.
Methods:
We injected this plasmid and a plasmid expressing a control peptide into oocytes either together with oncogenic p21 or in the presence of insulin (that induces maturation that is dependent on normal cellular ras-p21) in the presence and absence of the inducer isopropylthioglucose (IPTG).
Results:
Microinjection of this plasmid into oocytes together with Val 12-p21 resulted in complete inhibition of maturation in the presence of inducer. Another plasmid encoding the sequence for the unrelated control peptide, X13, was unable to inhibit Val 12-p21-induced maturation. In contrast, PNC2 plasmid had no effect on the ability of insulin-activated normal cellular or wild-type ras-p21 to induce oocyte maturation, suggesting that it is selective for blocking the mitogenic effects of oncogenic (Val 12) ras p21.
Conclusion:
We conclude that the PNC2 plasmid selectively inhibits oncogenic ras-p21 and may therefore be highly effective in blocking proliferation of ras-induced cancer cells. Also, from the patterns of inhibition, by PNC2 and other ras- and raf-related peptides, of raf- and constitutively activated MEK-induced maturation, we conclude that PNC2 peptide inhibits oncogenic ras p21 downstream of raf.
Insights
A novel peptide plasmid selectively inhibits oncogenic ras-p21, offering a potential strategy to block cancer cell proliferation. This peptide targets oncogenic ras-p21 downstream of raf, demonstrating specificity for cancer-driving mutations.
Area of Science:
- Molecular Biology
- Cell Biology
- Oncology
Background:
- The ras-p21 protein plays a critical role in cell signaling pathways.
- Oncogenic mutations in ras-p21, such as the Val 12 mutation, are frequently found in various cancers.
- Targeting these oncogenic forms of ras-p21 is a key strategy for cancer therapy.
Purpose of the Study:
- To synthesize an inducible plasmid expressing a peptide (PNC2) that targets oncogenic ras-p21.
- To evaluate the efficacy of this expression system in oocytes for selective inhibition of oncogenic ras-p21.
- To determine if the PNC2 peptide can inhibit proliferation of ras-transformed human cells.
Main Methods:
- Oocytes were microinjected with a plasmid expressing the PNC2 peptide or a control peptide.
- Experiments involved co-injection with oncogenic (Val 12) ras-p21 or induction with insulin.
- The role of isopropylthioglucose (IPTG) as an inducer was investigated.
Main Results:
- The PNC2 peptide plasmid completely inhibited Val 12-p21-induced oocyte maturation in the presence of the inducer.
- A control peptide (X13) did not inhibit Val 12-p21-induced maturation.
- The PNC2 plasmid did not affect maturation induced by normal cellular or wild-type ras-p21, indicating selectivity for oncogenic ras-p21.
Conclusions:
- The PNC2 plasmid selectively inhibits oncogenic ras-p21, showing promise for blocking proliferation in ras-induced cancers.
- The PNC2 peptide acts downstream of raf in the signaling pathway.
- This peptide-based system offers a potential therapeutic avenue for cancers driven by oncogenic ras-p21.