Compound K suppresses ultraviolet radiation-induced apoptosis by inducing DNA repair in human keratinocytes.

Ultraviolet (UV)-induced DNA damage is a crucial molecular trigger for sunburn cell formation and skin cancer. Nucleotide excision repair (NER) is the main mechanism in repairing UVB-induced DNA damage of mammalian cells. The purpose of this study is to investigate the functional role of ginsenoside compound K on HaCaT cells (a keratinocyte-derived permanent cell line) irradiated by UV. Hoechst 33258 staining were performed in analyzing UV-induced apoptosis on keratinocytes which were treated with compound K. ImmunoDotBlot assay was used in detecting cyclobutane pyrimidine dimers, the main DNA damage. Western blot analysis was applied for analyzing XPC and ERCC1, two of the NER proteins. Compound K inhibited UV-induced apoptosis of keratinocytes and caused a notable reduction in UV-specific DNA lesions which was due to induction of DNA repair. In agreement with this, compound K induced the expression of particular components of the NER complex, such as XPC and ERCC1. Our results demonstrate that compound K can protect cells from apoptosis induced by UV radiation by inducing DNA repair.

Inhibitory effects of Baicalin on ultraviolet B-induced photo-damage in keratinocyte cell line.

Baicalin, one kind of Chinese herbal medicine with anti-inflammatory and anti-oxidant property, has been commonly used as a clinical medicine. However, little has been known about the effects of Baicalin on ultraviolet (UV) induced photo-aging and photo-carcinogenesis. The photoproduct is critical to the initial event of UV-induced photo-carcinogenesis. The purpose of the present study was to investigate whether Baicalin, in immortalized human keratinocyte HaCaT cells, could inhibit ultraviolet-B (UVB) induced skin damage and its possible underlying mechanisms, such as inhibiting UVB-induced cytotoxicity and apoptosis, cyclobutane pyrimidine dimers (CPDs), down-regulating the expression of regulatory proteins which are related to cell apoptosis and DNA damage/repair. Our study revealed that Baicalin treatment could inhibit the UVB-induced cytotoxicity, apoptosis and CPD level. It also decreased the mRNA expression of apoptosis-regulatory genes (p53-p21 and c-fos), the protein levels of p53, proliferating cell nuclear antigen (PCNA) and repair protein A (RPA), and the secretion of cytokines [interleukin(IL)-6 and tumor necrosis factor (TNF-alpha)]. These results suggested that Baicalin may have an inhibitory effect on the UVB-induced photo-damage by blocking the relevant cytokine secretion and expression of p53-p21, c-fos, PCNA and RPA genes.

Hesperidin ameliorates UV radiation-induced skin damage by abrogation of oxidative stress and inflammatory in HaCaT cells.

Ultraviolet A (UVA) radiation contributes to skin photoaging. Hesperidin which is a flavanone glycoside found in citrus fruit peels, have been intensively studied for their UVA-protective activity, but its effects and mechanisms on UVA irradiation-induced inflammation and oxidative stress have never been described. Thus, the purpose of this study was to evaluate the effects of hesperidin in skin oxidative stress and inflammation induced by UVA irradiation. In this study, we firstly examined whether hesperidin may exert direct protective effects on the UVA-induced in human keratinocytes (HaCaT) cell injury in vitro. Cell viability was determined by MTT assay. The levels of superoxide dismutase (SOD), malondialdehyde (MDA) and total antioxidative capacity (T-AOC) were measured by using a commercially available kits. Quantitative reverse transcriptase PCR (qRT-PCR) and ELISA were used to determine messenger RNA (mRNA) and protein levels of the tumor necrosis factor (TNF)-α, interleukin (IL)-1ß and IL-6. UVA significantly decreased the cell viability (P<0.05). In our study, hesperidin (220µg/ml) significantly reduced UVA-induced oxidative stress and inflammatory response. In conclusion, hesperidin treatment effectively protected HaCaT keratinocytes from these UVA radiation-induced skin injuries, suggesting that the underlying mechanism involves the anti-oxidative and anti-inflammatory capacities, it is possible to be used as a sunscreen agent.

Ginsenoside Rb1 suppresses ultraviolet radiation-induced apoptosis by inducing DNA repair.

Ultraviolet (UV)-induced DNA damage is a crucial molecular trigger for sunburn cell formation and skin cancer. Nucleotide excision repair (NER) is the main mechanism in repairing UVB-induced DNA damage to mammalian cells. The purpose of this study was to investigate the functional role of ginsenoside Rb1 in UV-induced DNA damage and apoptosis in HaCaT (keratinocyte cell line) cells, and Xpc(-) knockout mouse keratinocytes. Flow cytometry and Hoechst 33258 staining were performed in analyzing UV-induced apoptosis in keratinocytes treated with ginsenoside Rb1. The ImmunoDotBlot assay was used to detect cyclobutane pyrimidine dimers, the main sign of DNA damage. Western blot analysis was applied for analyzing Xeroderma pigmentosum-C (XPC) and excision repair cross-complementing 1 (ERCC1), two of the NER proteins. Ginsenoside Rb1 inhibited UV-induced apoptosis of keratinocytes and caused a notable reduction in UV-specific DNA lesions which was due to induction of DNA repair. This reduction was not observed in Xpc(-) knockout keratinocytes. Ginsenoside Rb1 induced the expression of specific components of the NER complex, such as XPC and ERCC1. Our results demonstrate that ginsenoside Rb1 can protect cells from apoptosis induced by UV radiation by inducing DNA repair.

Effect of epigallocatechingallate on ultraviolet B-induced photo-damage in keratinocyte cell line.

One type of traditional Chinese medicines, epigallocatechingallate (EGCG) has been commonly used as a clinical and skin health protective ingredient. It has been known to have photo-protective, anti-inflammatory, and anti-oxidant effects. However, little is known about the mechanisms of EGCG on UV-induced photo-aging and photo-carcinogenesis. In the present study, we investigated the photo-protective mechanisms of EGCG on UVB-induced skin damage, including the potency of EGCG to inhibit the UVB-induced cytotoxicity, secretion of cytokine (IL-6 and TNF-alpha), cellular apoptosis, expression of apoptosis-regulatory genes (p53-p21) and c-fos gene in cultured immortalized human keratinocyte HaCaT cells. EGCG treatment decreased UVB- induced cell cytotoxicity and apoptosis. It also inhibited the mRNA expressions of apoptosis-regulatory gene (p53 and p21) and c-fos gene. These results suggest that EGCG may have an inhibitory effect on UVB-induced photo-damage and apoptosis by blocking the cytokine secretion and the mRNA expressions of p53, p21 and c-fos genes.