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Increasing DNA repair capacity in bone marrow by gene transfer as a prospective tool in cancer therapy
1Cancer Research Institute, Slovak Academy of Sciences, Bratislava.
Abstract:
Resistance of tumor cells to alkylating anticancer agents that produce adducts at the O6 position of guanine in DNA, the O6-alkylating agents, correlates with the expression of O6-alkylguanine-DNA alkyltransferase (ATase). O6-benzylguanine and related pseudosubstrates are able to inactivate human ATase in vitro and in vivo and they are being tested as chemotherapeutic adjuvants for enhancing the effectiveness of O6-alkylating drugs. On the other hand, the clinical consequences of ATase depletion may be fatal for some sensitive systems e.g. hematopoiesis. To overcome this problem, strategies for the protection of primary bone marrow cells by targeted transfer of pseudosubstrate-resistant ATase genes have been considered and recently achieved at the laboratory level. This approach could therefore be now extended to a clinical cancer gene therapy program.
Insights
Tumor cells resist O6-alkylating anticancer drugs via O6-alkylguanine-DNA alkyltransferase (ATase). Pseudosubstrates inactivate ATase, but protecting bone marrow cells with resistant ATase genes offers a promising cancer gene therapy approach.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Genetics
Background:
- Tumor cell resistance to O6-alkylating anticancer agents is linked to O6-alkylguanine-DNA alkyltransferase (ATase) expression.
- O6-benzylguanine and similar compounds inactivate ATase, showing potential as chemotherapeutic adjuvants.
- Depletion of ATase can cause severe side effects, particularly impacting hematopoiesis.
Purpose of the Study:
- To explore strategies for protecting normal tissues from ATase-inhibiting chemotherapy.
- To investigate the feasibility of using pseudosubstrate-resistant ATase genes for bone marrow cell protection.
- To assess the potential for clinical translation of gene therapy for enhancing chemotherapy safety.
Main Methods:
- In vitro and in vivo studies using O6-benzylguanine and related pseudosubstrates to inactivate human ATase.
- Development and testing of strategies for targeted gene transfer of pseudosubstrate-resistant ATase.
- Laboratory-level validation of bone marrow cell protection using gene therapy approaches.
Main Results:
- O6-benzylguanine effectively inactivates human ATase, enhancing the efficacy of O6-alkylating drugs.
- Successful laboratory-level demonstration of protecting primary bone marrow cells through targeted transfer of resistant ATase genes.
- Identification of a viable strategy to mitigate the toxic effects of ATase-depleting therapies.
Conclusions:
- Targeted gene transfer of pseudosubstrate-resistant ATase offers a potential method to protect critical tissues like bone marrow during chemotherapy.
- This approach holds promise for improving the safety and applicability of O6-alkylating agents in cancer treatment.
- The findings support the extension of this gene therapy strategy to clinical cancer treatment programs.