Inducible BCC Animal Model Using Skin-Specific Ptch1 and p53 Silencing
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Solution Overview
Problem
Existing mouse models for basal cell carcinoma (BCC) are either lethal, require prolonged UV or radiation exposure, or do not accurately replicate human BCC tumors, often developing secondary pathologies.
Innovation Solution
A genetically-modified non-human animal model with inducible expression of shRNAs targeting Ptch1 and p53, using a skin cell-specific promoter and recombinase system to induce BCC tumors efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Ptch1 knockout is performed in mice, then BCC tumor development is promoted, but the model becomes lethal
Solution Approach 1:
The patent divides the Ptch1 gene into two separate alleles: one allele carries a conditional knockout allele (Ptch1 flox/flox) that can be selectively removed in specific tissues, while the other allele remains intact as a backup. This segmentation allows the model to achieve complete Ptch1 deficiency in skin cells (promoting BCC) while maintaining Ptch1 function in other tissues (preventing lethality).
Solution Approach 2:
The patent applies tissue-specific Cre recombinase expression (under keratin 14 promoter) to remove the Ptch1 gene exclusively in epidermal cells. This creates local genetic modification where Ptch1 is knocked out only in the skin tissue where BCC develops, while other tissues retain normal Ptch1 function, thus avoiding systemic lethality.
2Object-affected harmful factors
If single copy deletion of Ptch1 is used, then lethality is avoided, but Ptch1 expression is still significantly maintained
Solution Approach 1:
The patent uses two separate alleles instead of a single heterozygous deletion. The first allele (Ptch1 flox/+) provides conditional knockout capability, while the second allele (Ptch1 flox/+) serves as a backup that can also be removed. This dual-allele approach ensures complete gene deficiency when both are activated, achieving reliable knockdown without the limitations of single-copy deletion.
Solution Approach 2:
The patent pre-prepares both alleles in a heterozygous state (Ptch1 flox/+) before inducing the disease model. This preliminary genetic configuration allows controlled, sequential removal of Ptch1 function. When Cre recombinase is expressed, it can remove the stop cassette from both alleles, achieving complete knockdown that is more reliable than single-copy deletion while still maintaining one functional copy during the setup phase to prevent lethality.
3Reliability
If conventional mouse models are used, then BCC tumors can be induced, but prolonged UV or radiation exposure is required
Solution Approach 1:
The patent performs preliminary genetic modification by establishing mice with both conditional Ptch1 knockout alleles before disease induction. This pre-configured genetic state creates cells that are primed and highly susceptible to BCC transformation. When combined with minimal UV exposure or other triggers, the pre-loaded genetic vulnerability allows rapid tumor development, eliminating the need for prolonged radiation exposure required in conventional models.
Solution Approach 2:
The patent fundamentally changes the key parameter of Ptch1 expression level by achieving near-complete knockout (compared to 50% reduction in heterozygous models). This parameter change creates a threshold effect where even minimal environmental stressors (low-dose UV, chemical carcinogens) are sufficient to trigger BCC transformation, dramatically reducing the time and intensity of external induction required.
4Reliability
If prolonged UV exposure is used to induce BCC, then tumors can be formed, but secondary pathologies develop
Solution Approach 1:
The patent pre-configures the genetic vulnerability (double heterozygous Ptch1 flox/+) before disease induction, creating a model where minimal environmental triggers are sufficient. This preliminary genetic setup allows the use of low-dose, short-duration UV exposure or alternative triggers (chemical carcinogens, mechanical injury) that induce BCC without the cumulative tissue damage and secondary pathologies associated with prolonged high-dose UV exposure in conventional models.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The model accurately recapitulates human BCC tumors and allows for rapid induction of BCC, facilitating effective evaluation of therapeutic interventions.
Implementation Method 1
whose genome comprises one or more sequences encoding a short hairpin RNA (shRNA) targeting Ptch1, and a shRNA targeting p53 or other tumor suppressor genes
Implementation Method 2
a gene encoding a site-specific recombinase that cleaves the upstream cleavable sequence
Data Source
AI summary
Methods for inducing basal cell carcinoma (BCC) or BCC tumors, as well as an inducible non-human animal models of BCC, are defined herein. The methods and animal models comprise targeting Ptch1 and/or a tumor suppressor gene via conditional expression of one or more short hairpin RNAs (shRNAs) in the skin of said animals.