Modify a human embryo to prevent hereditary breast cancer when one or both parents carry the breast cancer gene. - Your Published Bio Team Output
**Pre-Project**To achieve the goal of preventing hereditary breast cancer in a human embryo from parents carrying the breast cancer gene, we can consider modifying the endogenous pathway for DNA damage repair. Specifically, we can target genes involved in homologous recombination repair, such as BRCA1 and BRCA2, which are commonly mutated in hereditary breast cancer cases.
For importing a pathway from a different species, we can look at the elephant genome, which has been found to contain multiple copies of the tumor-suppressor gene TP53. Elephants have a significantly lower incidence of cancer than expected based on their large body size and the number of cells they have, and it is hypothesized that this may be due to their abundance of TP53 copies, which helps to detect and repair DNA damage. Therefore, importing this pathway or specific proteins from elephants could potentially enhance DNA damage repair in the human embryo and reduce the risk of hereditary breast cancer.
However, it is important to note that genetic modification of human embryos raises significant ethical concerns, and these must be carefully considered and addressed before any modifications are pursued. Additionally, there may be unknown consequences or unforeseen complications from modifying these pathways, so extensive testing and monitoring would need to be performed to ensure safety and efficacy.
**Genes:** Genes to add:
1. BRCA1: This gene plays an important role in the homologous recombination repair pathway for DNA damage. Mutations in BRCA1 can significantly increase the risk of hereditary breast cancer. Adding a functional copy of BRCA1 to the embryo's genome could potentially increase the efficiency of DNA damage repair and reduce the risk of developing breast cancer.
2. BRCA2: Similar to BRCA1, this gene is critical for the homologous recombination repair pathway and is frequently mutated in hereditary breast cancer cases. Adding a functional copy of BRCA2 could provide additional support for DNA damage repair and further decrease the risk of hereditary breast cancer.
3. TP53: As previously mentioned, elephants have multiple copies of TP53, a tumor-suppressor gene that helps to detect and repair DNA damage. Adding an additional copy of TP53 to the embryo's genome could potentially enhance DNA damage repair and provide an extra layer of protection against cancer.
4. CHEK2: This gene codes for a protein that is involved in DNA damage repair and cell cycle checkpoint control. Mutations in CHEK2 have been linked to an increased risk of breast cancer. Adding a functional copy of this gene could potentially improve DNA damage response and reduce the risk of developing breast cancer.
5. PALB2: This gene plays a critical role in DNA repair, specifically in the homologous recombination repair pathway. Mutations in PALB2 have been linked to an increased risk of breast cancer, particularly in individuals with a family history of the disease. Adding a functional copy of PALB2 could help to improve the efficiency of DNA damage repair and reduce the risk of hereditary breast cancer.
Genes to tweak expression:
1. CDH1: This gene encodes a protein that helps to maintain the integrity of cell-cell junctions. Mutations in CDH1 have been associated with an increased risk of hereditary diffuse gastric cancer and breast cancer. Decreasing the expression of this gene in the embryo could potentially reduce the risk of developing breast cancer.
2. PTEN: This gene is a tumor suppressor that plays a role in cell growth regulation and DNA repair. Mutations in PTEN have been linked to an increased risk of breast cancer. Increasing the expression of PTEN in the embryo could potentially improve DNA damage repair and reduce the risk of hereditary breast cancer.
3. RAD51: This gene is involved in DNA damage repair through the homologous recombination pathway. Altering the expression of RAD51 in the embryo could potentially improve the efficiency of DNA damage repair and reduce the risk of developing breast cancer.
4. ATM: This gene codes for a protein that is involved in DNA damage repair and cell cycle checkpoint control. Mutations in ATM have been linked to an increased risk of breast cancer. Increasing the expression of ATM in the embryo could potentially improve DNA damage repair and reduce the risk of developing hereditary breast cancer.
5. NBS1: This gene is involved in DNA damage repair and maintenance of genomic stability. Mutations in NBS1 have been associated with an increased risk of cancer, including breast cancer. Increasing the expression of NBS1 in the embryo could potentially lead to better DNA damage repair and reduce the risk of hereditary breast cancer.
**Regulatory Elements:** To prevent hereditary breast cancer in an embryo, we recommend adding functional copies of BRCA1, BRCA2, TP53, CHEK2, and PALB2 genes to increase the efficiency of DNA damage repair and help prevent the development of breast cancer. Additionally, we suggest altering the expression of CDH1 to decrease the risk of developing breast cancer while increasing the expression of PTEN, RAD51, ATM, and NBS1 to improve DNA damage repair and reduce the risk of hereditary breast cancer.
These changes may provide the embryo with a better resistance to breast cancer by improving the DNA repair mechanisms and increasing the cell's likelihood of detecting and repairing DNA damage. However, these changes may not entirely prevent the likelihood of developing breast cancer; hence, regular medical surveillance for breast cancer development is still necessary.
**Vector & Delivery:** Vector: A lentiviral vector is the most appropriate for delivering the genetic modifications to the human embryo. Lentiviral vectors can efficiently transfer genetic material into dividing and non-dividing cells, and they have a reduced risk of causing insertional mutagenesis, making them ideal for applications in gene therapy.
Delivery Method: The lentiviral vector can be delivered via microinjection into the embryo during in vitro fertilization. The microinjection is a method of delivering materials directly into cells without causing significant damage, making it an ideal delivery method for embryonic modifications. The lentiviral vector can then successfully integrate into the embryonic genome and provide the necessary genetic modifications.
Modification Based on Vector and Species: The lentiviral vector can efficiently deliver the genetic modifications into the embryonic cells, providing a better chance of a successful integration of the gene into the genome. Additionally, the microinjection delivery method is highly precise, allowing for targeted delivery to specific embryonic cells.
By using these specific vectors and delivery methods, the genetic modifications will optimize the desired outcome better than other methods. Lentiviral vectors are efficient at gene transfer, and microinjection is highly precise, making them the ideal choice for delivering genetic modifications to an embryonic cell.
**Selection Marker:** If a selection marker is deemed needed for this project, we will use a fluorescence marker, such as green fluorescent protein (GFP), to aid in the identification and selection of successfully modified embryos. GFP is a widely used and well-established marker that allows for rapid and reliable identification of modified cells. The lentiviral vector can be engineered to express GFP along with the genetic modifications, and embryos that have successfully integrated the lentiviral vector will express GFP, making them easily distinguishable from non-modified embryos. Overall, the use of a fluorescence marker provides a convenient and effective way to select embryos with successful genetic modifications.
**Transformation Protocol:** Protocol for Embryonic Gene Modification to Prevent Hereditary Breast Cancer:
1. Preparation of Lentiviral Vector:
a. Obtain a lentiviral vector with the desired genetic modifications (BRCA1, BRCA2, TP53, CHEK2, PALB2, CDH1, PTEN, RAD51, ATM, and NBS1).
b. Engineer the lentiviral vector to express GFP as a selection marker.
c. Prepare the lentiviral vector for transduction according to the manufacturer's instructions.
2. In vitro Fertilization:
a. Collect eggs and sperm from donors according to standard IVF protocols.
b. Perform in vitro fertilization (IVF) by incubating the eggs with sperm and allowing for fertilization.
c. Culture the resulting embryos until the blastocyst stage.
3. Microinjection of Lentiviral Vector:
a. Prepare a microinjection system with a microinjection pipette and a holding pipette.
b. Mix the lentiviral vector with suitable diluent (such as PBS) according to the manufacturer's instructions.
c. Gently place the embryo on the holding pipette.
d. Use the microinjection pipette to accurately deliver the desired volume of the vector solution into the embryo.
e. Transfer the embryo back to culture medium.
4. Monitoring and Selection of Modified Embryos:
a. Culture the modified embryos in suitable conditions, allowing for proper development.
b. Monitor the development and growth of the embryos.
c. Screen the embryos with a fluorescence microscope to identify modified embryos expressing the GFP selection marker.
d. Select the GFP-expressing embryos for further development and transfer to the uterus.
5. Transfer of Embryo and Follow-Up:
a. Transfer the selected embryos to the uterus of the recipient mother according to standard IVF protocols.
b. Monitor the pregnancy and the health of the fetus.
c. Perform regular screening for breast cancer in the child after birth.
a. Use sterile techniques when handling embryos to avoid bacterial or viral contamination.
b. Minimize the time and disturbance of the embryos during modification to avoid damage to the embryo.
c. Follow all appropriate safety measures and regulations for genetic modifications.
a. Use high-quality lentiviral vectors with a high titer and minimal toxicity.
b. Use precise and accurate microinjection techniques to deliver the vector into the embryo.
c. Culture modified embryos in optimal conditions to maximize viability and development.
**Gene cassette**: The 5' to 3' list of elements in the multipurpose cassette are as follows:
Note: In addition to the above elements, the cassette also includes cloning sites compatible with the chosen lentiviral vector.
The cassette contains gene expression cassettes for BRCA1, BRCA2, TP53, CHEK2, PALB2, CDH1 shRNA, PTEN, RAD51, ATM, and NBS1 genes. The order of the cassettes can be altered depending on the specific requirements of the project. The use of different spacers, such as 2A, P2A, T2A, and E2A, optimizes the co-expression of the genes within the same cassette.
The cassette includes lentiviral promoters, which are compatible with the chosen lentiviral vector, to allow for efficient transcription of the modified genes. Additionally, there are 3' polyadenylation signals to ensure proper termination of the transcription process and improve gene expression.
An shRNA expression cassette for CDH1 was included in the cassette to reduce the expression of this gene and thus decrease the risk of developing breast cancer. This modification can enhance the reliability of the genetic modifications in the embryo.
The lentiviral vector can be delivered through microinjection during in vitro fertilization, and a fluorescence marker such as GFP can be used as a selection marker to identify successfully modified embryos.
**Paper Abstract:** This project aims to reduce the risk of hereditary breast cancer by genetically modifying human embryos. The main objectives are to add functional copies of genes involved in DNA damage repair, such as BRCA1, BRCA2, and TP53, and alter the expression of genes such as CDH1 and PTEN to decrease the risk of breast cancer development. The lentiviral vector is chosen as the most appropriate vector for delivery to the embryo, and microinjection is used as the delivery method due to its precision. A fluorescence marker, such as GFP, is suggested as a selection marker to aid in the identification and selection of successfully modified embryos. The implications of this work are significant, as it has the potential to significantly reduce the risk of hereditary breast cancer in offspring. However, regular medical surveillance for breast cancer development is still recommended even after genetic modifications.
The optimal conditions for embryo growth in vitro must be maintained to ensure the success of the genetic modifications. The embryos should be cultured in a sterile, nutrient-rich environment with appropriate temperature and humidity levels. The pH of the culture media should be maintained between 7.2-7.4, and CO2 levels should be maintained at 5%. Proper aseptic techniques should be followed to prevent contamination, and regular monitoring of the culture media and embryos is necessary to ensure their health.
Once the embryos have been modified and cultured, the selection and identification of successfully modified embryos can be carried out using a fluorescence marker, such as GFP. Embryos displaying GFP expression can be identified and selected for implantation. Before the selection of modified embryos, a comprehensive genetic screening is necessary to exclude any possibility of unwanted genetic modifications or alterations.
After implantation, the modified embryos should be monitored regularly for the successful integration and stability of the genetic modifications. Additionally, an extensive genetic screening and health checkup should be conducted to ensure that the modifications have not caused any unintended genetic instability or aberrations that could lead to health issues or malformations. If any unintended side-effects are observed, the modifications can be evaluated and corrected through targeted genome editing or other genetic engineering tools. Regular medical check-ups, screening, and preventative measures are also necessary to monitor the possible development of breast cancer.
**Proliferation Method:** It is important to note that the use of a selection marker is not without potential drawbacks, such as the potential for toxicity or immunogenicity. Therefore, it is important to carefully consider the risks and benefits of using a selection marker before proceeding with its inclusion. It is also important to note that the use of a selection marker may not be necessary in all cases, as some genetic modifications may not require direct selection.
**Conclusion:** In conclusion, the development of a protocol for embryonic gene modification to prevent hereditary breast cancer has significant potential applications in reducing the risk of breast cancer in offspring. The protocol involves the use of lentiviral vectors to deliver gene modifications such as BRCA1, BRCA2, TP53, CHEK2, PALB2, CDH1, PTEN, RAD51, ATM, and NBS1. The use of a selection marker such as GFP aids in the identification and selection of successfully modified embryos. The success of the protocol is dependent on the careful optimization of growth, selection, and stabilization methods. The development of a gene construct containing cassette elements for the desired genes and regulatory elements is crucial for successful gene expression. Future research into the long-term safety and effectiveness of embryonic gene modification is necessary. Overall, this project is a significant step towards reducing the risk of hereditary breast cancer, and reflects the growing potential of genetic engineering as a tool for improving human health.