3.2. Cell Functions Involved in the Action
The major cell functions analyzed by DMA for TCM include: adipogenesis, anti-atherosclerosis, anti-carcinogenesis, anti-inflammation, apoptosis, carcinogenesis, chemoprevention, hypoxia, and life-span extension (Table 2; Figure 1).
Adipogenesis is a cellular differentiation process in whichpreadipocytes are transformed into differentiated adipocyte cells, and involves features such as morphological change, growth arrest, lipogenic gene expression, and the production of hormones and growth factors (such as leptin and TNF-α). Among the components found in the extract of Toddalia asiatica, aculeatin was found to promote the differentiation of mouse 3T3-L1 preadipocytes into adipocytes [132]. DMA revealed the involvement of PPAR-γ target genes in the process of activation by aculeatin, which is not a ligand of PPAR-γ, suggesting the presence of additional signaling mechanisms.
Atherosclerosis is a chronic inflammatory response of white blood cells in arterial blood vessels, which is promoted by low-density lipoproteins (LDLs), carriers of cholesterol, and triglycerides, and results in the formation of atherosclerotic plaques that are rich in macrophages and foam cells. Estrogenic activity was detected by DMA-based gene expression profiling in the extract of Agaricus blazei, which was attributable to brefeldin A [138]. The extract has no estrogen receptor-dependent cell proliferation activity, while showing activation of estrogen signaling (such as activation of ERK, Akt and P70S6K) and beneficial effects for patients with high levels of oxidized LDLs (see Section 3.3).
Carcinogenesis, alternatively referred to as oncogenesis or tumorigenesis, is a process by which normal cells are transformed into cancer cells characterized by uncontrolled cell division; it involves a progression of changes at the cellular, genetic, and epigenetic levels. Several chemicals exhibiting anti-carcinogenic effects were isolated or identified from natural products, such as 3,3′-diindolylmethane from cruciferous vegetables [145], grifolin from Albatrellus confluens [153], paeoniflorin from Paeonia lactiflora [161], and quercetin from various dietary plants [161], and further analyzed by DMA. 3,3′-Diindolylmethane is estrogenic and shows gene expression profiles favoring tumor promotion [145]. Grifolin acts negatively against the cell cycle and cell growth through inhibiting ERK and Rb pathways, and downregulates the expression of cyclin D1, cyclin E, and CDK4 (a gene for a cyclin-dependent kinase), and upregulates the expression of CKI (a CDK inhibitor gene) [153]. Paeoniflorin enhances the expression of HSP70, which helps to protect cells from stress, and modulates the expression of CDC2, FOSL1, and EGR1, regulators of cell growth and proliferation [161]. Quercetin, on the other hand, induces p53-independent apoptosis by enhancing the expression of death-receptor or TNFR signaling genes, such as the genes for caspase-10, DFF45, FAS, IκBα, IL1R (Interleukin-1 receptor), TNFR1, and TRAILR [171].
Inflammation is a protective response to cell injury, and involves the local vascular system, the immune system, and various cells within the injured tissue. Ergosterol peroxide produced by Sarcodon aspratus suppresses inflammatory response in macrophages by inhibiting TNF-α secretion and down-regulating the expression of interleukin1α/β (IL-1α/β) through pathways such as C/EBPβ, ERK, JNK, MAPK, and NF-κB [147].
Apoptosis is the process of programmed cell death that may occur in multicellular organisms in response to various stresses, such as heat, hypoxia, increased intracellular calcium concentration, nutrient deprivation, receptor–ligand binding, radiation, and viral infection. Several chemicals are related to the promotion of apoptosis and thus have been used as effective components in herbal medicine. Emodin extracted from the rhizomes of Rheum palmatum showed testicular toxicity, including the induction of apoptosis, most likely through pathways such as IGF-1, TGF/Wnt, and TNFR1 signaling [146]. β-Hydroxyisovalerylshikonin extracted from Lithospermum erythrorhizon is an inhibitor of protein-tyrosine kinases and induces apoptosis by suppressing TRAP1, a TNF-associated protein and a member of the HSPs, as well as the production of ROS [155]. Tanshinone IIA found in the root of Salvia miltiorrhiza induces peroxisome proliferator-activated receptor (PXR)/NF-κB/CCL2-mediated apoptosis in leukemia cells [180]. 2,4,3′,5′-Tetramethoxystilbene extracted from fruit, berries, and grapes is a derivative of resveratrol and a strong inducer of apoptosis by increasing the expression of tubulin, stress response, and pro-apoptotic genes [178].
Chemoprevention refers to the administration of a medication, such as drugs and vitamins, for the purpose of preventing disease or infection, and various chemicals have been developed especially for cancer chemoprevention. Myricetin [158] and sulforaphane [177] isolated from dietary plants show chemopreventive activity against cancer through activating Nrf2-mediated antioxidant response or PI3K/Akt signaling pathways, respectively.
Hypoxia is a condition in which a cell is deprived of adequate oxygen supply and has been shown to stimulate various biological and physiological responses. Paeonol isolated from Paeonia suffruticosa induces the expression of hypoxia-inducible genes, including hypoxia-inducible factor 1 (HIF-1)-target genes, through suppressing the NF-κB signaling pathway and inhibiting amyloid precursor protein (APP) activity [162].
Life extension has been studied in terms of slowing down or reversing the processes of aging in order to extend both the maximum and the average lifespan, and the effects of anti-aging products, nutrition, physical fitness, skin care, hormone replacements, vitamins, supplements, and herbs have been examined. Diallyl trisulfide isolated from garlic increases the longevity of nematodes through activation of the pro-longevity transcription factor gene skn-1 and the products of its target genes [144].
Conditions such as chronic (arthritis, asthma, cancer, diabetes, and viral diseases) and neurodegenerative (Parkinson’s and Alzheimer’s diseases) diseases have been treated with TCM [1], among which some were investigated by DMA and explored by animal tests and/or clinical studies to eventually achieve clinical applications. Other than the cell functions discussed above, the diseases with extensive impacts were also investigated. For example, antidepressant, anti-diabetic, anti-obesity, neuromodulation, and neuroprotection effects, and the treatments of neurological, Parkinson’s, and Alzheimer’s diseases associated with TMC and/or constituent herbs/mushrooms/dietary plants were studied by means of DMA (Table 1), or their effective components, such as ginsenosides (for diabetes), (−)-hydroxycitric acid (for obesity), obovatol (for neuroinflammation), and salvianolic acid B (for neuroprotection), were studied by means of DMA (Table 2).