Inhibition of chemotherapy-related breast tumor EMT by application of redox-sensitive siRNA delivery system CSO-ss-SA/siRNA along with doxorubicin treatment

A Comprehensive Review of Small Interfering RNAs (siRNAs): Mechanism, Therapeutic Targets, and Delivery Strategies for Cancer Therapy

Small interfering RNA (siRNA) delivery by nanocarriers has been identified as a promising strategy in the study and treatment of cancer. Short nucleotide sequences are synthesized exogenously to create siRNA, which triggers RNA interference (RNAi) in cells and silences target gene expression in a sequence-specific way. As a nucleic acid-based medicine that has gained popularity recently, siRNA exhibits novel potential for the treatment of cancer. However, there are still many obstacles to overcome before clinical siRNA delivery devices can be developed. In this review, we discuss prospective targets for siRNA drug design, explain siRNA drug properties and benefits, and give an overview of the current clinical siRNA therapeutics for the treatment of cancer. Additionally, we introduce the siRNA chemical modifications and delivery systems that are clinically sophisticated and classify bioresponsive materials for siRNA release in a methodical manner. This review will serve as a reference for researchers in developing more precise and efficient targeted delivery systems, promoting ongoing advances in clinical applications.

Cucurbitacin B inhibits TGF-β1-induced epithelial–mesenchymal transition (EMT) in NSCLC through regulating ROS and PI3K/Akt/mTOR pathways

Background

Lung cancer is the leading cause of cancer mortality worldwide, and most of the patients after treatment with EGF-TKIs develop drug resistance, which is closely correlated with EMT. Cucurbitacin B (CuB) is a natural product of the Chinese herb Cucurbitaceae plant, which has a favorable role in anti-inflammation and anti-cancer activities. However, the effect of CuB on EMT is still far from fully explored. In this study, the inhibition effect of CuB on EMT was investigated.

Methods

In this study, TGF-β1 was used to induce EMT in A549 cells. MTS assay was used to detect the cell viability of CuB co-treated with TGF-β1. Wound healing assay and transwell assay were used to determine the migration and invasion capacity of cells. Flow cytometry and fluorescence microscope were used to detect the ROS level in cells. Western blotting assay and immunofluorescence assay were used to detect the proteins expression. Gefitinib was used to establish EGF-TKI resistant NSCLC cells. B16-F10 intravenous injection mice model was used to evaluate the effect of CuB on lung cancer metastasis in vivo. Caliper IVIS Lumina and HE staining were used to detect the lung cancer metastasis of mice.

Results

In this study, the results indicated that CuB inhibited TGF-β1-induced EMT in A549 cells through reversing the cell morphology changes of EMT, increasing the protein expression of E-cadherin, decreasing the proteins expression of N-cadherin and Vimentin, suppressing the migration and invasion ability. CuB also decreased the ROS production and p-PI3K, p-Akt and p-mTOR expression in TGF-β1-induced EMT in A549 cells. Furthermore, Gefitinib resistant A549 cells (A549-GR) were well established, which has the EMT characteristics, and CuB could inhibit the EMT in A549-GR cells through ROS and PI3K/Akt/mTOR pathways. In vivo study showed that CuB inhibited the lung cancer metastasis effectively through intratracheal administration.

Conclusion

CuB inhibits EMT in TGF-β1-induced A549 cells and Gefitinib resistant A549 cells through decreasing ROS production and PI3K/Akt/mTOR signaling pathway. In vivo study validated that CuB inhibits lung cancer metastasis in mice. The study may be supporting CuB as a promising therapeutic agent for NSCLC and Gefitinib resistant NSCLC.

Erratum to: Inhibition of chemotherapy-related breast tumor EMT by application of redox-sensitive siRNA delivery system CSO-ss-SA/siRNA along with doxorubicin treatment

The online version of the original article can be found at https://doi.org/10.1631/jzus.B1900468 The original version of this article (Liu et al., 2020) unfortunately contained some mistakes. 1. Figs. 7c and 7d in p.229 were incorrect. The upper left and bottom left pictures in Fig. 7c were accidentally duplicated with the pictures at the same position of Fig. 1a. The upper right and bottom right pictures were mistakenly placed in Fig. 7c. Therefore, the calculation results in Fig. 7d were also mistaken. The correct versions should be as follows: 2. Because of the wrong pictures of Fig. 7c, the calculated results of "42.5%" in Abstract, Sections 3.9 and 5 are also mistaken. The correct result should be "45.2%." (1) Lines 10-12 of Abstract in p.218: "CSO-ss-SA/siRNA could effectively transmit siRNA into tumor cells, reducing the expression of RAC1 protein by 38.2% and decreasing the number of tumor-induced invasion cells by 42.5%." was incorrect. The correct version should be "CSO-ss-SA/siRNA could effectively transmit siRNA into tumor cells, reducing the expression of RAC1 protein by 38.2% and decreasing the number of tumor-induced invasion cells by 45.2%." (2) Lines 23-26 of Section 3.9 in p.227: "It was shown that the number of invasive tumor cells induced by DOX was reduced by 42.5% since CSO-ss-SA/siRNA downregulated the expression of RAC1 protein." was incorrect. The correct version should be "It was shown that the number of invasive tumor cells induced by DOX was reduced by 45.2% since CSO-ss-SA/siRNA downregulated the expression of RAC1 protein." (3) Lines 4-8 of Section 5 in p.231: "CSO-ss-SA, as an efficient redox-sensitive carrier for delivering siRNA silencing RAC1 into tumor cells, reduced the expression of RAC1 by 38.2% and decreased DOX-induced tumor invasion cells by 42.5% in vitro." was incorrect. The correct version should be "CSO-ss-SA, as an efficient redox-sensitive carrier for delivering siRNA silencing RAC1 into tumor cells, reduced the expression of RAC1 by 38.2% and decreased DOX-induced tumor invasion cells by 45.2% in vitro."

The involvement of epithelial-to-mesenchymal transition in doxorubicin resistance: Possible molecular targets

Considering the fact that cancer cells can switch among various molecular pathways and mechanisms to ensure their progression, chemotherapy is no longer effective enough in cancer therapy. As an anti-tumor agent, doxorubicin (DOX) is derived from Streptomyces peucetius and can induce cytotoxicity by binding to topoisomerase enzymes to suppress DNA replication, leading to apoptosis and cell cycle arrest. However, efficacy of DOX in suppressing cancer progression is restricted by development of drug resistance. Cancer cells elevate their metastasis in triggering DOX resistance. The epithelial-to-mesenchymal transition (EMT) mechanism participates in transforming epithelial cells into mesenchymal cells that have fibroblast-like features. The EMT diminishes intercellular adhesion and enhances migration of cells that are necessary for carcinogenesis. Various oncogenic molecular pathways stimulate EMT in cancer. EMT can induce DOX resistance, and in this way, upstream mediators such as ZEB proteins, microRNAs, Twist1 and TGF-β play a significant role. Identification of molecular pathways involved in EMT regulation and DOX resistance has resulted in using gene therapy such as microRNA transfection and siRNA in overcoming chemoresistance. Furthermore, curcumin and formononetin, owing to their cytotoxicity against cancer cells, can suppress EMT in mediating DOX sensitivity. For promoting efficacy in DOX sensitivity, nanoparticles have been developed for boosting ability in EMT inhibition.

Resveratrol and Its Analogs: Potent Agents to Reverse Epithelial-to-Mesenchymal Transition in Tumors

Epithelial-to-mesenchymal transition (EMT), a complicated program through which polarized epithelial cells acquire motile mesothelial traits, is regulated by tumor microenvironment. EMT is involved in tumor progression, invasion and metastasis via reconstructing the cytoskeleton and degrading the tumor basement membrane. Accumulating evidence shows that resveratrol, as a non-flavonoid polyphenol, can reverse EMT and inhibit invasion and migration of human tumors via diverse mechanisms and signaling pathways. In the present review, we will summarize the detailed mechanisms and pathways by which resveratrol and its analogs (e.g. Triacetyl resveratrol, 3,5,4'-Trimethoxystilbene) might regulate the EMT process in cancer cells to better understand their potential as novel anti-tumor agents. Resveratrol can also reverse chemoresistance via EMT inhibition and improvement of the antiproliferative effects of conventional treatments. Therefore, resveratrol and its analogs have the potential to become novel adjunctive agents to inhibit cancer metastasis, which might be partly related to their blocking of the EMT process.

Progress in Natural Compounds/siRNA Co-delivery Employing Nanovehicles for Cancer Therapy

Chemotherapy using natural compounds, such as resveratrol, curcumin, paclitaxel, docetaxel, etoposide, doxorubicin, and camptothecin, is of importance in cancer therapy because of the outstanding therapeutic activity and multitargeting capability of these compounds. However, poor solubility and bioavailability of natural compounds have limited their efficacy in cancer therapy. To circumvent this hurdle, nanocarriers have been designed to improve the antitumor activity of the aforementioned compounds. Nevertheless, cancer treatment is still a challenge, demanding novel strategies. It is well-known that a combination of natural products and gene therapy is advantageous over monotherapy. Delivery of multiple therapeutic agents/small interfering RNA (siRNA) as a potent gene-editing tool in cancer therapy can maximize the synergistic effects against tumor cells. In the present review, co-delivery of natural compounds/siRNA using nanovehicles are highlighted to provide a backdrop for future research.