Tumor Suppressor miR-184 Enhances Chemosensitivity by Directly Inhibiting SLC7A5 in Retinoblastoma.

The expression patterns and functional roles of miRNAs in retinoblastoma (RB) are poorly understood, especially those involved in chemoresistance. Here, we validated the expression pattern of 20 potential RB-suppressive miRNAs and confirmed that miR-184 is the most significantly decreased miRNA in human RB tissues, as well as chemoresistant cell line. Bioinformatic and molecular analyses revealed that SLC7A5 has three binding sites of miR-184 and significantly increased in RB tissues. miR-184 negatively correlated with SLC7A5 expression in RB tissues and mainly target position 2494-2513 of the SLC7A5 3'UTR to inhibit its expression. Furthermore, enforced expression of miR-184 reversed the oncogenic roles of SLC7A5 on proliferation, migration, and invasion of RB cells. In addition, miR-184 also enhances chemosensitivity of RB cells via inducing apoptosis and G2/M cell cycle arrest. Molecular studies revealed that miR-184-decreased phosphorylation status of known DNA damage repair sensors of the ATR/ATM pathways and induced persistent formation of γH2AX foci depend on targeting SLC7A5, leading to persistent DNA damage. Thus, targeting the miR-184/SLC7A5 pathway will provide new opportunities for drug development to reverse chemotherapeutic resistance in RB.

Whole-exome sequencing identifies novel mutations in genes responsible for retinitis pigmentosa in 2 nonconsanguineous Chinese families.

AIM: To detect the pathogenetic mutations responsible for nonsyndromic autosomal recessive retinitis pigmentosa (RP) in 2 nonconsanguineous Chinese families. METHODS: The clinical data, including detailed medical history, best corrected visual acuity (BCVA), slit-lamp biomicroscope examination, fundus photography, optical coherence tomography, static perimetry, and full field electroretinogram, were collected from the members of 2 nonconsanguineous Chinese families preliminarily diagnosed with RP. Genomic DNA was extracted from the probands and other available family members; whole-exome sequencing was conducted with the DNA samples provided by the probands, and all mutations detected by whole-exome sequencing were verified using Sanger sequencing in the probands and the other available family members. The verified novel mutations were further sequenced in 192 ethnicity matched healthy controls. RESULTS: The patients from the 2 families exhibited the typical symptoms of RP, including night blindness and progressive constriction of the visual field, and the fundus examinations showed attenuated retinal arterioles, peripheral bone spicule pigment deposits, and waxy optic discs. Whole-exome sequencing revealed a novel nonsense mutation in FAM161A (c.943A>T, p.Lys315*) and compound heterozygous mutations in RP1L1 (c.56C>A, p.Pro19His; c.5470C>T, p.Gln1824*). The nonsense c.5470C>T, p.Gln1824* mutation was novel. All mutations were verified by Sanger sequencing. The mutation p.Lys315* in FAM161A co-segregated with the phenotype, and all the nonsense mutations were absent from the ethnicity matched healthy controls and all available databases. CONCLUSION: We identify 2 novel mutations in genes responsible for autosomal recessive RP, and the mutation in FAM161A is reported for the first time in a Chinese population. Our result not only enriches the knowledge of the mutation frequency and spectrum in the genes responsible for nonsyndromic RP but also provides a new target for future gene therapy.

[Protective effects of melatonin on cultural human retinal pigment epithelial cells against oxidative damage in vitro].

OBJECTIVE: To investigate the protective effects of melatonin on the retinal pigment epithelium (RPE) against oxidative damage induced by hydrogen dioxide (H2O2) and its mechanism. METHODS: The RPE cells were seeded and divided into normal control group, oxidative damage group and the treatment group (treated with melatonin at the concentration of 1 x 10(-7) mol/L, 1 x 10(-6) mol/L, 1 x 10(-5) mol/L and 1 x 10(-4) mol/L). The model of oxidative damage on the RPE cells was established by culturing the RPE cells with H2O2 at the concentration of 600 micromol/L for 1 hour in vitro. The cell viability of RPE cells was detected by the methyl thiazolyl tetrazolium (MTT) method. The degree of oxidative damage was evaluated by detecting the superoxide dismutase (SOD) and maleic dialdehyde (MDA). Apoptosis was detected qualitatively using the DNA Ladders electrophoretic method, and quantitatively using the Annexin V-FITC/PI double staining flow cytometry. RESULTS: Compared with normal control group, the oxidative damage group had low cell viability, low SOD and high MDA contents, and high apoptosis rate (t = 2.25, 39.50, 68.42; P < 0.05). Compared with oxidative damage group, the treatment group had high cell viability, high SOD and low MDA contents, and low apoptosis rate (P < 0.05). CONCLUSIONS: Melatonin has a protective effect on the RPE against oxidative damage induced by H2O2. The mechanism may involve in reinforcing the cell viability, strengthening the activity of antioxidase, and reducing the apoptosis.