[Inhibition of COL1A1 and COL3A1 expression by RNA interference in human skin fibroblasts].

OBJECTIVE: To suppress COL1A1 and COL3A1 gene expressions in human skin fibroblasts (HSFs) by means of RNA interference (RNAi). METHODS: Three small interfering RNA (siRNA) expression cassette (SEC) sequences were designed for each of the COL1A1 and COL3A1 gene sequences available in GenBank. The synthesized SECs capable of effective gene suppression were transfected into cultured HSFs, either after cloning into the expression vector or mediated by Lipofectamine 2000, and the suppression of the target genes at both mRNA and protein levels was determined by quantitative fluorescence RT-PCR and Western blotting, respectively. RESULTS: Transfection of the SECs into HSFs resulted in specific depression of COL1A1 and COL3A1 expressions (down to 5.00% and 6.48%, respectively). The expression vector-mediated RNAi established a HSF cell line with persistent gene knockdown for over 30 days (to 25.21% and 22.12%, respectively). CONCLUSION: COL1A1 and COL3A1 gene expressions can be specifically and efficiently inhibited in HSFs by either liposome- or vector-mediated SEC transfection.

[Localization and differentiation of hair follicle stem cells].

OBJECTIVE: To identify the localization of hair follicles stem cell (HFSC) in different stages of hair and explore the differentiating capacity of HFSC into epidermis in vitro. METHODS: HFSC were detected by K19 immunostaining in normal human skin. Then, the isolated HFSC through enzyme digestion were seeded on dermal equivalent (DE) and cultured between the air-liquid interfaces for 14 days. Skin-equivalents was harvested and used for evaluation. RESULTS: HFSC mainly located in outer root sheet in hair follicle and human anagen hair follicles containing two distinct reservoirs for K19-positive cells located in the bulge and bulb of the follicle. These two reservoirs fused in line of outer root sheets during the catagen-telogen transition phase and individualized again in the newly forming anagen hair follicle. Based on DE, growing HFSC built a multilayered and confined epidermis. CONCLUSION: HFSC located in outer root sheets can promote hair cycle and differentiate into epidermis in vitro.

[Effects of histamine on proliferation, apoptosis and differentiation of human keratinocytes].

OBJECTIVE: To investigate the effects of histamine on the proliferation, apoptosis and differentiation of human keratinocytes (HKC) and the mechanisms. METHODS: The effect of histamine on the growth of HKC in vitro was examined by MTT assay and trypan blue exclusion assay. Cell cycle analysis and early apoptosis analysis by double staining with Annexin V-FITC and PI were carried out by flow cytometry. DNA ladder assay was performed for the detection of cell apoptosis. HKC free calcium concentration ([Ca(2+)](i)) was measured by laser scanning confocal microscopy in combination with calcium fluorescence probe Fluo-3/AM. HKC differentiation markers keratin 10 (K10) and involucrin was detected by streptavidinbiotin complex immunocytochemical assay. RESULTS: Histamine at high concentration inhibited the proliferation of HKC with cell viability ratio of 65.6% at 1 x 10(-4) mol/L, while histamine at low concentrations promoted proliferation of HKC with the cell viability ratio of 130.7% at 1 x 10(-8) mol/L. Histamine at 1 x 10(-4) mol/L altered cell cycle distribution of HKC with an increase in G0/G1-phase cell population to 30.97%, a decrease in S-phase population to 73.81% and inhibition of G1/S switching. Histamine at 1 x 10(-4) mol/L induced obvious apoptosis of HKC with early apoptosis ratio of 18.64% as compared with the control (5.60%, P<0.05). Histamine 1 x 10(-4) mol/L induced an increase of HKC [Ca(2+)](i) up to 58.9% and cimetidine (an H(2) receptor antagonist) decreased HKC [Ca(2+)](i) down to 25.4%. Histamine at this concentration down-regulated the expressions of K10 and involucrin of HKC but these changes were not significantly different from those of the control (P>0.05). CONCLUSIONS: Histamine at high concentrations inhibits cell cycle progress of HKC, mediates cell apoptosis and induces the increase of [Ca(2+)](i), which might be a partial explanation for growth arrest of HKC elicited by histamine. Histamine may regulate epidermal tissue turnover under physiological conditions, whereas under pathological circumstances of the skin as in trauma and inflammation, histamine at high concentrations may inhibit the regeneration of epidermis and the differentiation of HKC.

[Effects of all-trans-retinoic acid, acitretin and tazarotene on apoptosis and Bax/Bcl-2 expressions of human melanoma cells A375 and the significance].

OBJECTIVE: To investigate the effects of all-trans retinoic acid (ATRA), acitretin and tazarotene on apoptosis and Bax/Bcl-2 protein expressions of human melanoma A375 cells. METHODS: The effects of retinoids on apoptosis and Bax/Bcl-2 protein expressions of A375 cells in vitro were examined. Apoptosis analysis with double staining with annexin V-FITC and PI was performed using flow cytometer. SABC immunocytochemistry was employed for detection of Bax/Bcl-2 protein expressions. RESULTS: At the concentration of 1 x 10(-5) mol/L, ATRA, acitretin and tazarotene all induced apoptosis of A375 cells with apoptosis ratio of 5.03% (P<0.05), 13.42% (P<0.05) and 2.88% (P>0.05), respectively, and acitretin induced more significant apoptosis than the other two agents (P<0.05). In addition, all the three agents significantly increased the number of cells positive for Bax expression and decreased the number of cells expressing Bcl-2 (P<0.05), among which acitretin had the strongest effects. CONCLUSIONS: ATRA, acitretin and tazarotene mediate apoptosis of A375 cells possibly through, at least partially, the mitochondrial pathway. Acitretin may be utilized as a valuable alternative for treating melanoma.