The Most Competent Plant-Derived Natural Products for Targeting Apoptosis in Cancer Therapy

Cancer is a challenging problem for the global health community, and its increasing burden necessitates seeking novel and alternative therapies. Most cancers share six basic characteristics known as "cancer hallmarks", including uncontrolled proliferation, refractoriness to proliferation blockers, escaping apoptosis, unlimited proliferation, enhanced angiogenesis, and metastatic spread. Apoptosis, as one of the best-known programmed cell death processes, is generally promoted through two signaling pathways, including the intrinsic and extrinsic cascades. These pathways comprise several components that their alterations can render an apoptosis-resistance phenotype to the cell. Therefore, targeting more than one molecule in apoptotic pathways can be a novel and efficient approach for both identifying new anticancer therapeutics and preventing resistance to therapy. The main purpose of this review is to summarize data showing that various plant extracts and plant-derived molecules can activate both intrinsic and extrinsic apoptosis pathways in human cancer cells, making them attractive candidates in cancer treatment.

C₁₈H₁₇NO₆ Inhibits Invasion and Migration of Human MNNG Osteosarcoma Cells via the PI3K/AKT Signaling Pathway

Background

Osteosarcoma (OS) is a highly aggressive, metastatic bone tumor with a poor prognosis, and occurs more commonly in children and adolescents. Therefore, new drugs and treatments are urgently needed. In this study, we investigated the effect and potential mechanisms of C₁₈H₁₇NO₆ on osteosarcoma cells.

Material/Methods

Human MNNG osteosarcoma cells were treated with different concentrations of C₁₈H₁₇NO₆. The proliferation of the MNNG cells was examined via CCK-8 assay. Cell migration and invasion were tested via wound-healing assay and Transwell migration and invasion assays. ELISA was used to detect MMP-2, MMP-9, and VEGF secretion. Finally, Western blotting and qRT-PCR were used to detect protein and mRNA expressions, respectively.

Results

C₁₈H₁₇NO₆ inhibited MNNG proliferation in a dose- and time-dependent manner and inhibited MMP-2, MMP-9, and VEGF secretion. C₁₈H₁₇NO₆ treatment significantly downregulated N-cadherin and Vimentin expression levels and upregulated E-cadherin expression levels in vitro and in vivo. C₁₈H₁₇NO₆ inhibited tumor growth in a MNNG xenograft. We also found that C₁₈H₁₇NO₆ can significantly reduce the phosphorylation of the PI3K/AKT signaling pathway in vivo and in vitro. However, 740Y-P (a PI3K agonist) had the opposite effect on proliferation, migration and invasion of MNNG cells treated with C₁₈H₁₇NO₆. LY294002 (a PI3K inhibitor) downregulated p-PI3K and p-AKT could mimic the inhibitory effect of C₁₈H₁₇NO₆.

Conclusions

Our results suggest that C₁₈H₁₇NO₆ can inhibit human MNNG osteosarcoma cell invasion and migration via the PI3K/AKT signaling pathway both in vivo and in vitro. C₁₈H₁₇NO₆ may be a highly effective and low-toxicity natural drug for the prevention or treatment of OS.

Ethnopharmacology, phytochemistry, and pharmacology of Cornus officinalis Sieb. et Zucc

ETHNOPHARMACOLOGICAL RELEVANCE

Cornus officinalis (Cornaceae), known in Chinese as "Shanzhuyu," is a frequently used traditional Chinese medicine. It tastes sour and is astringent and slightly warm in nature. Its fruits have long been used to treat kidney deficiency, high blood pressure, waist and knee pain, dizziness, tinnitus, impotence, spermatorrhea, menorrhagia, and other diseases in China. The main distribution areas are Shanxi and Gansu.

AIM OF THE STUDY

This review focused on the ethnopharmacological uses of the herb. We also focus on the phytochemical, pharmacological, and toxicological studies on C. officinalis. The recent analytical methods developed for the quality control of the herb's constituents are also reviewed. Additionally, future trends and prospects in the study of this herb are proposed.

MATERIALS AND METHODS

Information on C. officinalis was gathered by searching the internet (PubMed, ScienceDirect, Wiley, ACS, CNKI, Scifinder, Web of Science, Google Scholar, and Baidu Scholar) and libraries.

RESULTS

This review compiled the ethnopharmacological uses, including the classic prescriptions and historical applications. Approximately 300 chemical compounds have been isolated and identified from C. officinalis. The major active components of the plant are organic acids and iridoids, among which morroniside and loganin have been extensively investigated. The fruit of the plant has been used in treating many diseases in traditional medicine. Scientific studies indicated the herb's wide range of pharmacological activities, such as hepatic and renal protection, antidiabetes activity, cardioprotection, antioxidation, neuroprotection, antitumor activity, anti-inflammation, analgesic effects, antiaging activity, antiamnesia, antiosteoporosis, and immunoregulation. The analytical methods developed for the quantitative and qualitative determination of various compounds in the herb were further reviewed.

CONCLUSIONS

In this paper, we reviewed various studies conducted on C. officinalis, especially in areas of its ethnopharmacological use, as well as on its phytochemistry, pharmacology, and modern analytical methods used. Some of the herb's ethnomedical indications have been confirmed by the herb's pharmacological effects, such as its hepatic and renal protection and the antidiabetic effects. In particular, the crude extract and its chemical composition have exerted good therapeutic effect in diabetic treatment. C. officinalis entails additional attention on its pharmacological effects and drug development to expand its effective use clinically. Many advanced technologies are used for quality testing, but the detection component is exceedingly scarce for synthetically evaluating the quality of C. officinalis herbs. Thus, further research is necessary to investigate the quality control and toxicology of the plant, to further elucidate its clinical use, and to control herbal quality.

Ethyl acetate extract of Peperomia tetraphylla induces cytotoxicity, cell cycle arrest, and apoptosis in lymphoma U937 cells

The current study evaluated the cytotoxicity and the mechanism of apoptotic induction by Peperomia tetraphylla in U937 lymphoma cells. The results showed that P. tetraphylla ethyl acetate extract (EAEPT) inhibited the cell growth in U937 cells by MTT assay. After the U937 cells were treated with EAEPT, the cells exhibited marked morphological features of apoptosis (Hoechst 33342 staining) and the number of apoptotic cell (Annexin V-FITC/PI staining) increased. The treatment of EAEPT could induce loss of mitochondrial membrane potential (MMP) and increase the ROS level. Moreover, EAEPT treatment resulted in the accumulation of cells at S phase. We found that EAEPT could induce the cleavage of the caspase 3, caspase 8, caspase 9 and Bid. And the treatment of EAEPT could increase expression of Bax and down-regulate the expression of CCNB1, CCND1 and CDK1. The sub-fraction of EAEPT, namely EASub1 demonstrated the highest cytotoxicity activity on U937 cells. It was confirmed that EAEPT could inhibit the growth of U937 cells by blocking the cell cycle and prompted apoptosis via the ROS-medicated mitochondria pathway in vitro.

Antitumor effects of traditional Chinese medicine targeting the cellular apoptotic pathway

Defects in apoptosis are common phenomena in many types of cancer and are also a critical step in tumorigenesis. Targeting the apoptotic pathway has been considered an intriguing strategy for cancer therapy. Traditional Chinese medicine (TCM) has been used in the People’s Republic of China for thousands of years, and many of the medicines have been confirmed to be effective in the treatment of a number of tumors. With increasing cancer rates worldwide, the antitumor effects of TCMs have attracted more and more attention globally. Many of the TCMs have been shown to have antitumor activity through multiple targets, and apoptosis pathway-related targets have been extensively studied and defined to be promising. This review focuses on several antitumor TCMs, especially those with clinical efficacy, based on their effects on the apoptotic signaling pathway. The problems with and prospects of development of TCMs as anticancer agents are also presented.