Efficient Sequential Co-Delivery Nanosystem for Inhibition of Tumor and Tumor-Associated Fibroblast-Induced Resistance and Metastasis

Abstract

Purpose

Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer. However, the effect of current treatment strategies by inducing tumor cell apoptosis alone is not satisfactory. The growth, metastasis and treatment sensitivity of tumors can be strongly influenced by cancer-associated fibroblasts (CAFs) in the microenvironment. Effective cancer therapies may need to target not only the tumor cells directly but also the CAFs that protect them.

Methods

Celastrol and small-sized micelles containing betulinic acid were co-encapsulated into liposomes using the thin-film hydration method (CL@BM). Folic acid was further introduced to modify liposomes as the targeting moiety (F/CL@BM). We established a novel NIH3T3+4T1 co-culture model to mimic the tumor microenvironment and assessed the nanocarrier’s inhibitory effects on CAFs-induced drug resistance and migration in the co-culture model. The in vivo biological distribution, fluorescence imaging, biological safety evaluation, and combined therapeutic effect evaluation of the nanocarrier were carried out based on a triple-negative breast cancer model.

Results

In the present study, a novel multifunctional nano-formulation was designed by combining the advantages of sequential release, co-loading of tretinoin and betulinic acid, and folic acid-mediated active targeting. As expected, the nano-formulation exhibited enhanced cytotoxicity in different cellular models and effectively increased drug accumulation at the tumor site by disrupting the cellular barrier composed of CAFs by tretinoin. Notably, the co-loaded nano-formulations proved to be more potent in inhibiting tumor growth in mice and also showed better anti-metastatic effects in lung metastasis models compared to the formulations with either drug alone. This novel drug delivery system has the potential to be used to develop more effective cancer therapies.

Conclusion

Targeting CAFs with celastrol sensitizes tumor cells to chemotherapy, increasing the efficacy of betulinic acid. The combination of drugs targeting tumor cells and CAFs may lead to more effective therapies against various cancers.

Keywords:

• liposomes
• targeted delivery
• triple-negative breast cancer
• anti-tumor
• combination therapy
• sequential drug delivery

Ethics Approval and Consent to Participate

All in vivo procedures have been approved by Animal Ethics Committee of the Center for Experimental Animal Research of Southern Medical University (number: swum 20220817033).

Acknowledgments

We gratefully acknowledge technical support by the Public Platform of Advanced Detecting Instruments, Public Center of Experimental Technology, Southwest Medical University.

Disclosure

The authors report no conflicts of interest in this work.

Additional information

Funding

This work was supported by the [Sichuan Science and Technology Program #1] under Grant [number 23NSFSC0666]; [Sichuan Science and Technology Program #2] under Grant [number 22YFS0614] and [the key research and development project fund of social development of [Luzhou Science and Technology Bureau #3] under Grant (number 2022-SYF-56).