Gene Therapy 1 Flashcards
(55 cards)
What is the aim of gene therapy?
Deliver a GENE to overcome or treat diseases (genetic or acquired)
Name the current genetic therapy targets
1) Cancer
2) Monogenic disease
3) Infectious disease
4) CVD
What can be delivered to block the expression of a faulty gene?
A different gene that produces a product blocking the faulty gene’s expression, resulting in normal cell function for cancer.
What is a suicide gene?
A gene that, when delivered to a cell, results in the production of a toxic chemical that kills the cell.
What happens after an enzyme is delivered and expressed in a targeted cell?
A substrate for that enzyme is delivered, which is converted into a toxic compound that kills the targeted cells.
What is the effect of the toxic compound produced by the targeted cells?
It will kill only the cells that are being targeted.
What is gene replacement used for?
Gene replacement is used for genetic disorders such as cystic fibrosis (CF) and sickle cell disease.
What are suicide genes?
Suicide genes encode enzymes that activate a toxic drug.
What is an example of a suicide gene therapy?
An example is HSV-TK combined with ganciclovir.
This is also known as gene-directed enzyme prodrug therapy (GDEPT).
What is the efficiency of HSV-TK compared to mammalian kinases?
HSV-TK has greater than 1,000-fold efficiency in phosphorylating ganciclovir than mammalian kinases.
How are suicide genes delivered into tumor cells?
Suicide genes are incorporated into a non-mammalian enzyme to deliver it into tumor cells.
What is required for the effectiveness of suicide gene therapy?
The tumor cells must express the gene and produce the product.
What happens to dsDNA in nucleic acid based therapy?
It is chopped up into small pieces of between 21-25 base pairs in length, forming siRNA.
What occurs if viral mRNA is found in nucleic acid based therapy?
The siRNA will be unwound into ssRNA and will bind to the complementary region within the mRNA.
What is formed during the nucleic acid based therapy process?
RNA induced silencing complexes are formed, which cleave the RNA into two and stop translation of the protein.
What is the effect of nucleic acid based therapy on viral proteins?
It stops viral proteins from being translated.
Can nucleic acid based therapy be used to knock down our own proteins?
Yes, it can be used to knock down our own proteins.
How can siRNAs be designed in nucleic acid based therapy?
They can be designed to be complementary to a region of the protein’s mRNA.
What is an example of a protein involved in a disease state that can be targeted?
VEGF protein or receptor can be targeted.
What is the outcome of delivering designed siRNA to cells?
It interferes with the mRNA, causes its cleavage, and reduces the expression of the gene ultimately at the protein level.
What is miRNA and how is it related to nucleic acid based therapy?
miRNA is derived from specific genes and codes for specific RNAs, causing destabilization and reduction of translation into protein.
Name 2 main delivery routes
Viral vectors
Non-viral vectors
Name the challenges to delivery of genetic material
Very large
Hard to get across some membranes particularly easy
Unstable in serum - chemically modify them to make them more stable
Sometimes can mature into lysosomes which can degrade once in the cytoplasm
Difficulties crossing the nuclear membrane
Can be degraded once in the cytoplasm
Name three viral vectors
Retroviruses
Adenoviruses
Adeno-associated virus (AAV)
