In vitro assays suggest Shenqi Fuzheng Injection has the potential to alter melanoma immune microenvironment

Abstract

Ethnopharmacological relevance

A modern agent Shenqi Fuzheng Injection (SFI), prepared from Codonopsis Radix and Astragali Radix, has been commonly used as a supplementary therapy for cancers including melanoma. This agent was derived from a formula documented in the “National Collection of Chinese Medicine Prescriptions”. The formula has long been used as a remedy for Qi deficiency that is closely associated with cancer-related fatigue and poor quality of life. However, the antimelanoma mechanisms of SFI remain unclear. Here we tested if SFI exerted antimelanoma effects by reprograming the tumour immune microenvironment using in vitro assays.

Materials and methods

The cytotoxic activities of Jurkat T cells when co-cultured with A375 cells were determined in the presence or absence of SFI. The migratory activities of Jurkat T cells were examined in the transwell assay system. The mRNA expression and production of cytokines (IL-10, TGF β and VEGF) in A375 cells in the presence or absence of SFI were determined by real-time PCR and ELISA, respectively.

Results

When A375 cells were co-cultured with Jurkat T cells in the presence of SFI (220 µg/mL), a potent cytotoxicity effect against A375 cells was observed. Supernatants from A375 cells that were treated with SFI (110 and 220 µg/mL) significantly increased the migratory capacity of Jurkat T cells in transwell assays. SFI also markedly reduced the mRNA expression levels and the release of immunosuppressive cytokines IL-10, TGF-β and VEGF in A375 cells in a concentration-dependent manner.

Conclusions

SFI enhanced the cytotoxic and migratory activities of Jurkat T cells towards A375 melanoma cells. The effects were associated with SFI's suppression on immunosuppressive cytokines for their release from and gene expressions in A375 melanoma cells. These in vitro findings suggested that SFI might reprogramme the immunosuppressive melanoma microenvironment in vivo to enhance the cytotoxicity of tumour-infiltrating immune cells. This study provides a pharmacological basis for the adjunctive use of SFI in melanoma treatment.

Introduction

Melanoma, a highly malignant tumour, accounts for the vast majority (80%) of skin cancer related-deaths (Bertolotto, 2013). During the past decade, the incidence of cutaneous malignant melanoma is increasing tremendously (Merrill et al., 2015). The clinical use of targeted therapy and immunotherapy is challenged by their emerging resistance and toxicity (Chapman, 2013, Grossmann and Margolin, 2015). Therefore, novel inexpensive, safe and effective therapeutic approaches for melanoma are urgently needed.

Traditional Chinese medicine (TCM) has grabbed appreciable attention in recent years as it is a safe and inexpensive option complementary to Western medicine in managing cancer (Liang et al., 2014). A modern TCM agent Shenqi Fuzheng Injection (參芪扶正注射液, SFI), prepared from Codonopsis Radix (the dried roots of Codonopsis pilosula (Franch.) Nannf., 黨參) and Astragali Radix (the dried roots of Astragalus membranaceus (Fisch.) Bge. var. mongholicus (Bge.) Hsiao, 蒙古黃芪) at a ratio of 1:1, has been commonly used as a supplementary therapy for cancer patients concurrent with or after radio- and/or chemotherapies. The agent was derived from a formula consisting of the mentioned two herbs (參芪膏, Shenqigao) that is documented in the “National Collection of Chinese Medicine Prescriptions” (全國中藥成藥處方集) (issued in 1962) as a remedy for Qi deficiency that is closely associated with cancer-related fatigue and poor quality of life (Chien et al., 2012). These two herbs have traditionally been used for treating vital energy deficiency (Qi deficiency in TCM) with minimal toxicities. Both herbs are capable of inhibiting growth and metastasis of various types of cancer in vitro and in vivo (Cho and Leung, 2007, Qi et al., 2015, Woo et al., 2013, Xin et al., 2012, Yin et al., 2015). The two herbs are clinically used in conjunction with other Chinese medicinal materials for managing cancers including melanoma (Cassileth et al., 2009, Huo et al., 2013). SFI has been shown to improve the quality of life in cancer patients received conventional therapies (Bo et al., 2007, Liang et al., 2009, Zheng et al., 2007) and exhibit synergistic antitumour effects with chemical drugs in cancer models (Dong et al., 2010a, Dong et al., 2010b). However, the mode and mechanism of action of SFI in melanoma treatment remain unclear. Some studies suggested that SFI can enhance the immunity of cancer patients and tumour-bearing animals (Guo et al., 2015, Wang and DuBois, 2015, Yin et al., 2013). For instance, SFI has been shown to increase the phagocytic activity of macrophage in immunosuppressed mice (Wang et al., 2012).

Like other solid tumours, melanoma can create an immunosuppressive microenvironment by i) secreting immunosuppressive cytokines such as transforming growth factor β (TGF-β) and interleukin-10 (IL-10) (Sun et al., 2014); ii) releasing vascular endothelial growth factor (VEGF) to suppress immune-cell infiltration (Ott et al., 2015); iii) impairing the functions of tumour-infiltrating immune cells (Whiteside, 1998) and so on. In this study, for the first time, we using in vitro assays tested if SFI exerted anti-melanoma effects by altering the tumour immune microenvironment.