Cancer:
Lung, leukemia, cervical, breast, leukemia/lymphoma, choriocarcinoma
Action: Demethylation, anti-tumor immunity, induces apoptosis
Breast
The 27-kDa trichosanthin (TCS) is a ribosome inactivating protein purified from tubers of the Chinese herbal plant Trichosanthes kirilowii Maximowicz (tian hua fen). Fang et al. (2012) extended the potential medicinal applications of TCS from HIV, ferticide, hydatidiform moles, invasive moles, to breast cancer. They found that TCS manifested anti-proliferative and apoptosis-inducing activities in both estrogen-dependent human MCF-7 cells and estrogen-independent MDA-MB-231 cells.
Leukemia/Lymphoma, Cervical Cancer, Choriocarcinoma
Trichosanthin (TCS) as a midterm abortifacient medicine has been used clinically in traditional Chinese medicine for centuries. Additionally, TCS manifests a host of pharmacological properties, for instance, anti-HIV and anti-tumor activities. TCS has been reported to inhibit cell growth of a diversity of cancers, including cervical cancer, choriocarcinoma, and leukemia/lymphoma, etc. Sha et al. (2013) reviewed the various anti-tumor activities of TCS and the mechanism of apoptosis it induced in these tumor cells.
Lung, Anti-tumor Immunity
In this study, Cai et al. (2011) focused on the effect of TCS on murine anti-tumor immune response in the 3LL Lewis lung carcinoma tumor model and explored the possible molecular pathways involved. In addition to inhibiting cell proliferation and inducing apoptosis in the 3LL tumor, TCS retarded tumor growth and prolonged mouse survival more significantly in C57BL/6 immunocompetent mice than in nude mice. Data demonstrate that TCS not only affects tumor cells directly, but also enhances anti-tumor immunity via the interaction between TSLC1 and CRTAM.
Induce Apoptosis
Over the past 20 years, TCS has been the subject of much research because of its potential anti-tumor activities. Many reports have revealed that TCS is cytotoxic in a variety of tumor cell lines in vitro and in vivo. Monoclonal antibody-conjugated TCS could enhance its anti-tumor efficacy; thus, TCS is considered to be a potential biological agent for cancer treatment. TCS is able to inhibit protein synthesis and consequently induce necrosis. Recent studies have demonstrated that TCS does indeed induce apoptosis in several tumor cell lines (Li et al., 2010).
Leukemia
Cultured human leukemia K562 cells treated with trichosanthin were examined. Analysis of the cells by single laser flow cytometry showed the sub-G1 peak. DNA extracted from these cells formed a characteristic 'ladder' on agarose gel electrophoresis. Under electromicroscope, typical morphological changes of apoptosis were also observed. From all of these findings, Kang et al. (1998) concluded that trichosanthin was able to induce apoptosis in K562 cells.
Cervical Cancer, Demethylation Activity
Epigenetic silencing of tumor suppressor genes is a well-established oncogenic process and the reactivation of tumor suppressor genes that have been silenced by promoter methylation is an attractive molecular target for cancer therapy. In this study, Huang et al. (2012) investigated the demethylation activity of trichosanthin and its possible mechanism of action in cervical cancer cell lines. HeLa human cervical adenocarcinoma and CaSki human cervical squamous carcinoma cells were treated with various concentrations (0, 20, 40 and 80 µg/ml) of TCS for 48 hours and the mRNA and protein expression levels of the tumor suppressor genes adenomatous polyposis coli (APC) and tumor suppressor in lung cancer 1 (TSLC1) were detected using reverse transcription (RT)-PCR and Western blotting, respectively.
TCS induced demethylation in HeLa and CaSki cells and this demethylation activity was accompanied by the decreased expression of DNMT1 and reduced DNMT1 enzyme activity. Results demonstrate for the first time that TCS is capable of restoring the expression of methylation-silenced tumor suppressor genes and is potentially useful as a demethylation agent for the clinical treatment of human cervical cancer.
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