PHB2-Derived Peptides Blocking BIG3-PHB2 in Breast Cancer
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Solution Overview
Problem
Current endocrine therapies for breast cancer, such as tamoxifen and aromatase inhibitors, are often ineffective against estrogen receptor-positive and triple-negative breast cancers, and the molecular mechanisms behind their efficacy are not well understood.
Innovation Solution
Development of PHB2-derived peptides that specifically inhibit the BIG3-PHB2 interaction, which are designed to target and suppress breast cancer cell growth by reactivating the tumor suppressive activity of PHB2, thereby inhibiting estrogen-dependent signaling pathways.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current endocrine therapies (tamoxifen, aromatase inhibitors) are used to treat breast cancer, then some clinical effects are achieved, but the therapies are often ineffective against estrogen receptor-positive and triple-negative breast cancers, and molecular mechanisms are not well understood
Solution Approach 1:
The patent identifies BIG3-PHB2 interaction as a key intermediary mechanism in estrogen signaling regulation. BIG3 acts as a mediator that binds to PHB2 (a tumor suppressor) to inhibit its tumor suppressive activity, thereby causing constitutive ERα activation. This intermediary mechanism explains why current endocrine therapies fail - they do not target this critical interaction pathway.
Solution Approach 2:
The patent extracts the critical functional region from PHB2 (amino acids 11-22 and 76-90) to create peptides that specifically inhibit the BIG3-PHB2 interaction. By taking out only the essential binding regions, the invention develops targeted therapeutic agents that disrupt the harmful interaction without requiring full-length PHB2 expression, thereby overcoming the limitations of current therapies.
2Reliability
If PHB2 is used as a target to suppress breast cancer growth, then tumor suppressive activity is reactivated, but PHB2 expression is found in organs throughout the human body, causing non-selective effects
Solution Approach 1:
The patent applies local quality by targeting specific local regions (amino acid sequences 11-22 and 76-90 of PHB2) rather than the entire protein. The peptides are designed to bind specifically to these local regions on PHB2 that are critical for the BIG3-PHB2 interaction, thereby disrupting the interaction locally in cancer cells without affecting PHB2 function in normal organs throughout the body.
Solution Approach 2:
The patent segments the PHB2 protein into functional regions, identifying amino acid sequences 11-22 and 76-90 as critical for binding to BIG3. By creating peptides from these segmented regions, the invention achieves selective inhibition of the harmful interaction while preserving overall PHB2 function in normal tissues, thereby reducing non-selective effects.
3Reliability
If a BIG3-derived inhibitory peptide (ERAP) is used to inhibit the BIG3-PHB2 interaction, then breast cancer cell growth is suppressed, but the peptide cannot distinguish between cancer tissue and normal tissue expressing PHB2
Solution Approach 1:
Instead of using a BIG3-derived peptide (ERAP) that binds to PHB2, the invention inverts the approach by using PHB2-derived peptides that bind to BIG3. This inversion creates a selective advantage because BIG3 is overexpressed in breast cancer cells but not in normal tissues, while PHB2 is widely expressed. The PHB2-derived peptides specifically target the cancer-specific overexpression of BIG3, thereby achieving tissue selectivity.
Solution Approach 2:
The patent changes the parameter of peptide origin from BIG3-derived to PHB2-derived, and optimizes the amino acid sequences (positions 11-22 and 76-90) to maximize binding affinity for BIG3. This parameter change, combined with the selective overexpression of BIG3 in cancer cells, enables the peptides to distinguish between cancer and normal tissues, achieving both growth suppression and tissue selectivity.
Data Source
AI summary
The present invention provides peptides containing the BIG3 polypeptide-binding site in a PHB2 polypeptide, which inhibit the binding between a PHB2 polypeptide and a BIG3 polypeptide, and pharmaceutical compositions containing the peptide. The peptides of the present invention have the ability to bind not to PHB2, whose expression is found in organs throughout the human body, but to BIG3, which is a protein highly expressed specifically in particularly estrogen receptor-positive cancer, and have excellent growth suppressive effects on BIG3-positive cancer cells. Accordingly, the peptides of the present invention are useful as therapeutic agents for breast cancer which can avoid expression of side effects.