OBJECTIVEThis paper aims to study the effects of gossypol acetic acid (GAA) on proliferation and methylation level of human MutL homologue 1 (hMLH1) gene in human tongue cancer cell line Tca8113.

METHODSThe MTT assay was used to determine the effects of the acid on the proliferation inhibition in Tca8113 cells treated with different GAA concentrations. Nested methylation-specific polymerase chain reaction (nMSP) was used to detect the change in the methylation level of hMLH1 after 48 and 72 h with 30 and 15 micro mol L(-1) GAA treatment.

RESULTSMTT assay results showed the growth and proliferation inhibition of Tca8113 cells in the experimental GAA group after 24 h to 72 h of GAA treatment. The nMSP results indicated that the average optical density of hMLH1 in the Tca8113 cells significantly changed after the GAA treatment (30 micro mol L(-1) GAA for 48 h and 15 micro mol L(-1) for 72 h) (P<0.05) compared with that of the control group.

CONCLUSIONGAA does not only inhibit Tca8113 proliferation but also has a demethylation effect on the hMLH1 gene. These phenomena may be part of an underlying tumor-suppression mechanism of GAA.

Cell Line ; Cell Line, Tumor ; Cell Proliferation ; Gossypol ; analogs & derivatives ; Humans ; Methylation ; Tongue Neoplasms

Objective To evaluate the effect of miRNA-29 (miR-29) family on the synthesis of collagen Ⅰ and Ⅲ in chronically photodamaged (photoaged) skin.Methods Some cultured human dermal fibroblasts (HDFs) were divided into 2 groups:non-irradiated group receiving no treatment,and chronic photodamage group treated with repetitive ultraviolet A (UVA) radiation,which served as a chronically photodamaged cell model and was verified by flow cytometry and β-galactosidase staining.Western blot analysis was performed to determine the protein expression of collagen Ⅰ and Ⅲ,and real-time fluorescence-based quantitative PCR (qRT-PCR) to measure expression of 3 members of the miR-29 family (miR-29a-3p,miR-29b-3p and miR-29c-3p) in the above 2 groups.The differentially expressed miR-29c-3p between the above 2 groups was chosen for further functional tests.Some HDFs were divided into 4 groups to be transfected with fluorescein-labelled miR-29c-3p mimics (overexpression group),inhibitors (inhibition group),and their control RNA oligonucleotides (negative control group and inhibitor control group) respectively.The transfection efficiency was evaluated by the proportion of fluorescent cells,and the relative expression of miR-29c-3p in the above 4 groups was measured by qRT-PCR for evaluating the RNA interference efficiency,qRT-PCR was conducted to determine the mRNA expression of collagen type Ⅰ α1 (COL1A1) and collagen type Ⅲ α1 (COL3A1) genes,and Western blot analysis to measure the protein expression of collagen Ⅰ and Ⅲ.Results Compared with the non-irradiated group,the chronic photodamage group showed significantly increased proportion of senescent cells (36.47％ ± 3.20％ vs.12.56％ ± 1.46％,P ＜ 0.01) and G1-phase cells (71.70％ ± 2.43％ vs.41.89％ ± 1.86％,P ＜ 0.01),but significantly decreased proportion of S-phase cells (10.63％ ± 0.36％ vs.36.48％ ± 1.31％,P ＜ 0.01),which indicated that the chronically photodamaged cell model was established successfully.The protein expression of collagen Ⅰ and Ⅲ was significantly lower in the chronic photodamage group (0.40 ± 0.19 and 0.52 ± 0.10) than in the non-irradiated group (1.00 ± 0.12 and 1.00 ± 0.10,respectively,both P ＜ 0.01).The expression of miR-29c-3p was significantly higher in the chronic photodamage group than in the non-irradiated group (4.42 ± 2.05 vs.0.89± 0.10,P ＜ 0.05),while there were no significant differences in the expression of miR-29a-3p or miR-29b-3p between the 2 groups (both P ＞ 0.05).Twenty-four hours after transfection,the overexpression group and inhibition group both showed more than 90％ transfection efficiency which met the interference requirements.The expression of miR-29c-3p was significantly higher in the overexpression group than in the negative control group (224.17 ± 2.00 vs.2.45 ± 0.34,P ＜ 0.01),but significantly lower in the inhibition group than in the inhibitor control group (0.20 ± 0.08 vs.2.24± 0.14,P ＜ 0.01),suggesting that a RNA interference model was successfully established.The mRNA expression of COL1A1 and COL3A1 and the protein expression of collagen Ⅰ and Ⅲ were significantly lower in the overexpression group than in the negative control group and inhibition group (all P ＜ 0.05),and significantly higher in the inhibition group than in the inhibitor control group (all P ＜ 0.01).Conclusion The expression of miR-29c-3p is up-regulated in chronically photodamaged HDFs,likely by regulating the mRNA expression of COL1A1 and COL3A1 and the protein expression of collagen Ⅰ and Ⅲ.