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Cancer is a physiological condition that has both the endogenous and exogenous influences on its progression. It originatesfrom unusual cell growth, where the cells undergo massive genetic alterations, bypass the signaling machinery andcompromise its genetic cohesion. Literature has well narrated the DNA damage studies including driver mutations thatinterfere with the treatment strategies. However, with evolving medical excellence, recent day studies are trying to unveilthe contribution of RNAs in the progression of tumor malignancies. A number of non-coding RNAs have been identified asan active component in cancer genomics. This article aims to review the role of long non-coding RNAs in the spectra ofcancers and its prognostic value as the biomarkers in molecular targeting with clinical utility and therapeutic beneficence.
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Objective@#To evaluate the effects of repeated ultraviolet A (UVA) radiation on DNA damage, repair and replication processes in human skin fibroblasts, and to explore their mechanisms.@*Methods@#Fibroblasts were isolated from the circumcised foreskins of 3 children in the Department of Urological Surgery, Third Affiliated Hospital, Sun Yat-sen University, and subjected to a primary culture. Cultured human skin fibroblasts of 3rd-10th passages were divided into 2 groups: UVA group treated with repeated UVA radiation to establish a chronic photodamaged cell model, and control group receiving no treatment. Cell counting kit 8 (CCK-8) assay, β-galactosidase staining and flow cytometry were performed to assess cellular proliferative activity, and determine the proportion of photoaged cells and apoptosis rate respectively. Reverse transcription reaction was performed to establish a differentially expressed cDNA library, which was then subjected to high-throughput sequencing. The cDNA sequencing results were compared between the control group and UVA group, and the differentially expressed genes were analyzed in Kyoto Encyclopedia of Genes and Genomes (KEGG) database. The data were compared between the two groups by using two independent sample t test.@*Results@#Compared with the control group, the UVA group showed significantly decreased cellular proliferative activity (72.0% ± 5.2% vs. 96.0% ± 3.7%, t = 6.51, P < 0.05) , but significantly increased proportion of photoaged cells (79.7% ± 5.2% vs. 6.4% ± 0.8%, t=24.12, P < 0.05) and apoptosis rate (29.0% ± 3.3% vs. 6.0% ± 5.9%, t= 5.89, P < 0.05) . Among the key enzymes involved in DNA mismatch repair, replication and base excision repair processes, the expression of DNA ligase 1 (Lig1) , ribonuclease (RNase) H2A and helicase Dna2 in the UVA group was 0.47 ± 0.13, 0.44 ± 0.07 and 0.49 ± 0.11 times (all P < 0.01) that in the control group respectively. After the UVA-induced chronic photodamage in the human skin fibroblasts, After the UVA-induced chronic photodamage in the human skin fibroblasts, Lig expression decrease could block DNA single-base excision repair, Lig and Lig1 expression decrease could block DNA multiple-base excision repair, Lig1 expression decrease could block DNA mismatch repair, and RNaseH2A, Dna2 and Lig1 expression decrease could block DNA replication.@*Conclusion@#Repeated UVA radiation can change the expression of key enzymes involved in DNA base excision repair, DNA mismatch repair and DNA replication processes in skin fibroblasts, and then affect DNA repair and DNA replication processes in skin fibroblasts.
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Objective To evaluate the effects of repeated ultraviolet A (UVA) radiation on DNA damage,repair and replication processes in human skin fibroblasts,and to explore their mechanisms.Methods Fibroblasts were isolated from the circumcised foreskins of 3 children in the Department of Urological Surgery,Third Affiliated Hospital,Sun Yat-sen University,and subjected to a primary culture.Cultured human skin fibroblasts of 3rd-10th passages were divided into 2 groups:UVA group treated with repeated UVA radiation to establish a chronic photodamaged cell model,and control group receiving no treatment.Cell counting kit 8 (CCK-8) assay,β-galactosidase staining and flow cytometry were performed to assess cellular proliferative activity,and determine the proportion of photoaged cells and apoptosis rate respectively.Reverse transcription reaction was performed to establish a differentially expressed cDNA library,which was then subjected to high-throughput sequencing.The cDNA sequencing results were compared between the control group and UVA group,and the differentially expressed genes were analyzed in Kyoto Encyclopedia of Genes and Genomes (KEGG) database.The data were compared between the two groups by using two independent sample t test.Results Compared with the control group,the UVA group showed significantly decreased cellular proliferative activity (72.0％ ± 5.2％ vs.96.0％ ± 3.7％,t =6.51,P ＜ 0.05),but significantly increased proportion of photoaged cells (79.7％ ± 5.2％ vs.6.4％ ± 0.8％,t =24.12,P ＜ 0.05) and apoptosis rate (29.0％ ± 3.3％ vs.6.0％ ± 5.9％,t =5.89,P ＜ 0.05).Among the key enzymes involved in DNA mismatch repair,replication and base excision repair processes,the expression of DNA ligase 1 (Lig1),ribonuclease (RNase) H2A and helicase Dna2 in the UVA group was 0.47 ± 0.13,0.44 ± 0.07 and 0.49 ± 0.11 times (all P ＜ 0.01) that in the control group respectively.After the UVAinduced chronic photodamage in the human skin fibroblasts,After the UVA-induced chronic photodamage in the human skin fibroblasts,Lig expression decrease could block DNA single-base excision repair,Lig and Lig1 expression decrease could block DNA multiple-base excision repair,Lig1 expression decrease could block DNA mismatch repair,and RNaseH2A,Dna2 and Lig1 expression decrease could block DNA replication.Conclusion Repeated UVA radiation can change the expression of key enzymes involved in DNA base excision repair,DNA mismatch repair and DNA replication processes in skin fibroblasts,and then affect DNA repair and DNA replication processes in skin fibroblasts.
ABSTRACT
Mesenchymal stem cells (MSCs), which are multipotent and have self-renewal ability, support the regeneration of damaged normal tissue. A number of external stimuli promote migration of MSCs into peripheral blood and support their participation inwound healing. In an attempt to harness the potential beneficial effects of such external stimuli, we exposed human MSCs (hMSCs) to one such stimulus-low-dose ionizing radiation (LDIR)-and examined their biological properties. To this end, we evaluated differences in proliferation, cell cycle, DNA damage, expression of surface markers (CD29, CD34, CD90, and CD105), and differentiation potential ofhMSCs before and after irradiation with γ-rays generated using a ¹³⁷ CSirradiator.At doses less than 50 mGy, LDIR had no significant effect on the viability or apoptosis of hMSCs. Interestingly, 10 mGyofLDIR increased hMSC viability by 8% (p<0.001) comparedwith non-irradiatedhMSCs.At doses less than 50 mGy, LDIR did not induceDNA damage, including DNA strand breaks, or cause cellular senescence or cell-cycle arrest. Surface marker expression and in vitro differentiation potential of hMSCs were maintained after two exposures to LDIR at 10 mGy per dose. In conclusion, a two-dose exposure to LDIR at 10 mGy per dose not only facilitates proliferation of hMSCs, it alsomaintains the stem cell characteristics of hMSCswithout affecting their viability.These results provide evidence for the potential ofLDIRas an external stimulus for in vitro expansion of hMSCs and application in tissue engineering and regenerative medicine.