Proposed Implementation

Colorectal cancer is one of the leading causes of cancer-related mortality worldwide(Dekker et al., 2019). Colorectal cancer remains a significant challenge, especially when using non-targeted treatments like traditional chemotherapy. While chemotherapy with drugs such as 5-Fluorouracil (5-FU) and oxaliplatin has been effective in reducing tumor size and improving survival, it faces several limitations. One major issue is the lack of specificity, which means these drugs not only attack cancer cells but also harm healthy cells, leading to severe side effects like nausea, fatigue, and immune suppression.

Moreover, many patients eventually develop chemoresistance, rendering these treatments less effective over time. This lack of precision, combined with the toxic side effects, creates a significant challenge in colorectal cancer treatment, highlighting the need for more effective and personalized approaches.

Targeted therapies, such as anti-VEGF and anti-EGFR drugs, have improved colorectal cancer treatment by inhibiting specific molecular pathways. However, their efficacy is limited by factors like gene mutations and acquired resistance, restricting their benefit to certain patient groups.

In contrast, siRNA-based therapies represent a promising new approach. siRNA (small interfering RNA) works by silencing specific genes involved in cancer progression, offering precise control over oncogenic pathways at the genetic level. We propose siRNA therapy targeting TEAD4 to treat colorectal cancer. RNAi-based therapy offers several advantages over traditional treatments, such as small molecules and protein-based drugs(Debele et al., 2023). Firstly, siRNA therapies typically exhibit only antagonistic effects, in contrast to conventional therapies that may produce both agonistic and antagonistic effects. Secondly, siRNA can target intracellular, extracellular, and even “undruggable” targets, unlike small molecules and protein-based therapies, which are often more restricted. Thirdly, siRNA shows high specificity, comparable to protein-based therapies but superior to small molecules. Lastly, siRNAs are relatively easy to synthesize, similar to small molecules, but unlike protein-based therapies. The siRNA-based approach provides a highly specific, effective, and patient-friendly option for cancer treatment(Nakamura et al., 2011).

One major limitation of siRNA therapy in cancer treatment is the difficulty in delivering the siRNA molecules effectively to tumor cells due to issues like poor stability in the bloodstream and potential off-target effects. Additionally, ensuring efficient and targeted delivery without triggering immune responses remains a significant challenge. To enhance siRNA functionality and improve properties such as stability and delivery efficiency, various chemical modifications have been implemented. These modifications have been shown to increase the half-life of siRNA, improve its stability in the bloodstream, modulate immune responses, and reduce off-target effects. By employing such modifications, we expect to develop a highly effective siRNA-based therapy for colorectal cancer. Figure 1 outlines the relevant oligonucleotide chemical modifications for siRNA optimization(Pendergraff et al., 2016).

Intravenous administration is the preferred route for delivering siRNA therapies. Once administered, the modified siRNA is protected from degradation and aggregation in the bloodstream, allowing it to reach the tumor cells via the circulatory system. Upon entering the target cells, siRNAs bind with the RNA-induced silencing complex (RISC), which degrades the sense strand and incorporates the antisense strand.

In our main experiment, we designed two plasmids that effectively suppress TEAD4 expression. Our data demonstrate that elevated levels of TEAD4-targeting siRNAs in the colorectal cancer cell line SW480 result in reduced tumor cell proliferation and migration, along with increased reactive oxygen species (ROS) production. These findings suggest that this RNA interference (RNAi) vector is a promising therapeutic candidate for colorectal cancer treatment. The plasmids successfully facilitate the incorporation of the RISC complex, which subsequently cleaves TEAD4 mRNA, effectively downregulating its expression. This mechanism underscores the potential of siRNA therapy in the clinical management of cancer. (Friedrich and Aigner, 2022).

As siRNA technology continues to evolve, significant efforts are focused on optimizing gene silencing while minimizing adverse effects in vivo. Despite challenges such as delivery efficiency and off-target effects, several siRNA-based therapies have already gained clinical approval, with numerous others progressing through late-stage clinical trials. Targeting non-coding RNAs with siRNAs or constructing recombinant oncolytic viruses may open new avenues for cancer therapy(Shchaslyvyi et al., 2023).

Debele, T.A., Chen, C.K., Yu, L.Y., and Lo, C.L. (2023). Lipopolyplex-Mediated Co-Delivery of Doxorubicin and FAK siRNA to Enhance Therapeutic Efficiency of Treating Colorectal Cancer. Pharmaceutics 15. 10.3390/pharmaceutics15020596.

Dekker, E., Tanis, P.J., Vleugels, J.L.A., Kasi, P.M., and Wallace, M.B. (2019). Colorectal cancer. Lancet 394, 1467-1480. 10.1016/S0140-6736(19)32319-0.

Friedrich, M., and Aigner, A. (2022). Therapeutic siRNA: State-of-the-Art and Future Perspectives. BioDrugs 36, 549-571. 10.1007/s40259-022-00549-3.

Nakamura, K., Abu Lila, A.S., Matsunaga, M., Doi, Y., Ishida, T., and Kiwada, H. (2011). A double-modulation strategy in cancer treatment with a chemotherapeutic agent and siRNA. Mol Ther 19, 2040-2047. 10.1038/mt.2011.174.

Pendergraff, H.M., Debacker, A.J., and Watts, J.K. (2016). Single-Stranded Silencing RNAs: Hit Rate and Chemical Modification. Nucleic Acid Ther 26, 216-222. 10.1089/nat.2015.0557.

Shchaslyvyi, A.Y., Antonenko, S.V., Tesliuk, M.G., and Telegeev, G.D. (2023). Current State of Human Gene Therapy: Approved Products and Vectors. Pharmaceuticals (Basel) 16. 10.3390/ph16101416.