Exploring Cytotoxic mRNAs as a Novel Class of Anti-cancer Biotherapeutics
Kristin Hirschberger1, Anita Jarzebinska2, Eva Kessel2
1Ethris GmbH, Planegg 82152, Germany.
Abstract:
New treatments to overcome the obstacles of conventional anti-cancer therapy are a permanent subject of investigation. One promising approach is the application of toxins linked to cell-specific ligands, so-called immunotoxins. Another attractive option is the employment of toxin-encoding plasmids. However, immunotoxins cause hepatoxicity, and DNA therapeutics, among other disadvantages, bear the risk of insertional mutagenesis. As an alternative, this study examined chemically modified mRNAs coding for diphtheria toxin, subtilase cytotoxin, and abrin-a for their ability to reduce cancer cell growth both in vitro and in vivo. The plant toxin abrin-a was the most promising candidate among the three tested toxins and was further investigated. Its expression was demonstrated by western blot. Experiments with firefly luciferase in reticulocyte lysates and co-transfection experiments with EGFP demonstrated the capability of abrin-a to inhibit protein synthesis. Its cytotoxic effect was quantified employing viability assays and propidium iodide staining. By studying caspase-3/7 activation, Annexin V-binding, and chromatin condensation with Hoechst33258 staining, apoptotic cell death could be confirmed. In mice, repeated intratumoral injections of complexed abrin-a mRNA resulted in a significant reduction (89%) of KB tumor size compared to a non-translatable control mRNA.
Insights
Chemically modified mRNA encoding abrin-a shows promise as a novel cancer therapy. Intratumoral injection of abrin-a mRNA significantly reduced tumor size in mice, offering a potential alternative to conventional treatments.
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- Conventional anti-cancer therapies face challenges like toxicity and mutagenesis.
- Immunotoxins and toxin-encoding plasmids have limitations, including hepatotoxicity and insertional mutagenesis risk.
- Chemically modified messenger RNAs (mRNAs) offer a potential alternative for targeted cancer therapy.
Purpose of the Study:
- To evaluate the efficacy of chemically modified mRNAs encoding diphtheria toxin, subtilase cytotoxin, and abrin-a against cancer cells.
- To investigate abrin-a mRNA as a potential anti-cancer therapeutic agent.
- To assess the anti-tumor activity of abrin-a mRNA in a murine tumor model.
Main Methods:
- Chemically modified mRNAs encoding three different toxins were synthesized.
- In vitro studies included protein synthesis inhibition assays (using firefly luciferase and EGFP) and cytotoxicity assessments (viability assays, propidium iodide staining).
- Apoptosis was confirmed via caspase-3/7 activation, Annexin V-binding, and Hoechst33258 staining.
- In vivo studies involved repeated intratumoral injections of abrin-a mRNA in a KB tumor mouse model.
Main Results:
- Abrin-a mRNA demonstrated the most promising anti-cancer activity among the tested toxins.
- Abrin-a mRNA successfully inhibited protein synthesis in vitro.
- Cytotoxicity and induction of apoptotic cell death were confirmed for abrin-a.
- Intratumoral injection of abrin-a mRNA resulted in an 89% reduction in KB tumor size in mice compared to control mRNA.
Conclusions:
- Chemically modified mRNA encoding abrin-a is a potent inhibitor of cancer cell growth.
- Abrin-a mRNA represents a promising, novel therapeutic strategy for cancer treatment.
- The study validates abrin-a mRNA as a viable alternative to overcome limitations of existing cancer therapies.
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