Analysis of lncRNAs expression in UVB-induced stress responses of melanocytes

Long intergenic non‑coding RNA‑p21 mediates cardiac senescence via the Wnt/β‑catenin signaling pathway in doxorubicin-induced cardiotoxicity

Doxorubicin (Dox)-induced cardiotoxicity has been a well‑known phenomenon to clinicians and scientists for decades. It has been confirmed that Dox‑dependent cardiotoxicity is accompanied by cardiac cellular senescence. However, the molecular mechanisms underlying Dox cardiotoxicity remains to be fully elucidated. Long non‑coding (lnc) RNAs regulate gene transcription and the fate of post‑transcriptional mRNA, which affects a broad range of age‑associated physiological and pathological conditions, including cardiovascular disease and cellular senescence. However, the functional role of lncRNAs in Dox‑induced cardiac cellular senescence remains largely unknown. Using the reverse transcription‑quantitative polymerase chain reaction method, the present study indicated that long intergenic non‑coding (linc) RNA‑p21 was highly expressed in Dox‑treated HL‑1 murine cardiomyocytes. Dox‑induced cardiac senescence was accompanied by decreased cellular proliferation and viability, increased expression of p53 and p16, and decreased telomere length and telomerase activity, while these effects were relieved by silencing endogenous lincRNA‑p21. We found that lincRNA‑p21 interacted with β‑catenin and that silencing β‑catenin abolished the anti‑senescent effect of lincRNA‑p21 silencing. It was observed that modulating lincRNA‑p21 to exert an anti‑senescent effect was dependent on decreasing oxidant stress. To conclude, the present findings suggest that lincRNA‑p21 may be involved in Dox‑associated cardiac cellular senescence and that silencing lincRNA‑p21 effectively protects against Dox cardiotoxicity by regulating the Wnt/β‑catenin signaling pathway and decreasing oxidant stress. Furthermore, modulating lincRNA‑p21 may have cardioprotective potential in patients with cancer receiving Dox treatment.

Inhibition of REDD1 Sensitizes Bladder Urothelial Carcinoma to Paclitaxel by Inhibiting Autophagy

Purpose: Regulated in development and DNA damage response-1 (REDD1) is a stress-related protein and is involved in the progression of cancer. The role and regulatory mechanism of REDD1 in bladder urothelial carcinoma (BUC), however, is yet unidentified.Experimental Design: The expression of REDD1 in BUC was detected by Western blot analysis and immunohistochemistry (IHC). The correlation between REDD1 expression and clinical features in patients with BUC were assessed. The effects of REDD1 on cellular proliferation, apoptosis, autophagy, and paclitaxel sensitivity were determined both in vitro and in vivo Then the targeted-regulating mechanism of REDD1 by miRNAs was explored.Results: Here the significant increase of REDD1 expression is detected in BUC tissue, and REDD1 is first reported as an independent prognostic factor in patients with BUC. Silencing REDD1 expression in T24 and EJ cells decreased cell proliferation, increased apoptosis, and decreased autophagy, whereas the ectopic expression of REDD1 in RT4 and BIU87 cells had the opposite effect. In addition, the REDD1-mediated proliferation, apoptosis, and autophagy are found to be negatively regulated by miR-22 in vitro, which intensify the paclitaxel sensitivity via inhibition of the well-acknowledged REDD1-EEF2K-autophagy axis. AKT/mTOR signaling initially activated or inhibited in response to silencing or enhancing REDD1 expression and then recovered rapidly. Finally, the inhibited REDD1 expression by either RNAi or miR-22 sensitizes BUC tumor cells to paclitaxel in a subcutaneous transplant carcinoma model in vivoConclusions: REDD1 is confirmed as an oncogene in BUC, and antagonizing REDD1 could be a potential therapeutic strategy to sensitize BUC cells to paclitaxel. Clin Cancer Res; 24(2); 445-59. ©2017 AACR.

microRNA-33a-5p increases radiosensitivity by inhibiting glycolysis in melanoma

Glycolysis was reported to have a positive correlation with radioresistance. Our previous study found that the miR-33a functioned as a tumor suppressor in malignant melanoma by targeting hypoxia-inducible factor1-alpha (HIF-1α), a gene known to promote glycolysis. However, the role of miR-33a-5p in radiosensitivity remains to be elucidated. We found that miR-33a-5p was downregulated in melanoma tissues and cells. Cell proliferation was downregulated after overexpression of miR-33a-5p in WM451 cells, accompanied by a decreased level of glycolysis. In contrast, cell proliferation was upregulated after inhibition of miR-33a-5p in WM35 cells, accompanied by increased glycolysis. Overexpression of miR-33a-5p enhanced the sensitivity of melanoma cells to X-radiation by MTT assay, while downregulation of miR-33a-5p had the opposite effects. Finally, in vivo experiments with xenografts in nude mice confirmed that high expression of miR-33a-5p in tumor cells increased radiosensitivity via inhibiting glycolysis. In conclusions, miR-33a-5p promotes radiosensitivity by negatively regulating glycolysis in melanoma.

Nrf2 in keratinocytes modulates UVB-induced DNA damage and apoptosis in melanocytes through MAPK signaling

Responses of melanocytes (MC) to ultraviolet (UV) irradiation can be influenced by their neighbouring keratinocytes (KC). We investigated the role of Nrf2 in regulating paracrine effects of KC on UVB-induced MC responses through phosphorylation of MAPKs in association with oxidative stress in primary human MC cocultured with primary human KC using a transwell co-culture system and small-interfering RNA-mediated silencing of Nrf2 (siNrf2). The mechanisms by which Nrf2 modulated paracrine factors including α-melanocyte-stimulating hormone (α-MSH) and paracrine effects of KC on UVB-mediated apoptosis were also assessed. Our findings showed that co-culture of MC with siNrf2-transfected KC enhanced UVB-mediated cyclobutane pyrimidine dimer (CPD) formation, apoptosis and oxidant formation, together with phosphorylation of ERK, JNK and p38 in MC. Treatment of MC with conditioned medium (CM) from Nrf2-depleted KC also increased UVB-mediated MC damage, suggesting that KC modulated UVB-mediated MC responses via paracrine effects. Additionally, depletion of Nrf2 in KC suppressed UVB-induced α-MSH levels as early as 30min post-irradiation, although pretreatment with N-acetylcysteine (NAC) elevated its levels in CM from siNrf2-transfected KC. Furthermore, NAC reversed the effect of CM from Nrf2-depleted KC on UVB-induced apoptosis and inflammatory response in MC. Our study demonstrates for the first time that KC provided a rescue effect on UVB-mediated MC damage, although depletion of Nrf2 in KC reversed its protective effects on MC in a paracrine fashion in association with elevation of ROS levels and activation of MAPK pathways in MC. Nrf2 may indirectly regulate the paracrine effects of KC probably by affecting levels of the paracrine factor α-MSH via a ROS-dependent mechanism.

MALAT1 participates in ultraviolet B-induced photo-aging via regulation of the ERK/MAPK signaling pathway

Long non-coding RNA (lncRNA), transcripts of >200 bp in length that do not appear to exhibit any coding capacity, are important in the occurrence and development of cancer, cardiovascular and neurological diseases. However, effects of lncRNAs on photo-aging remain to be elucidated. To explore the potential effects of the lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) on photo-aging in fibroblasts, MALAT1 expression was silenced in fibroblasts using small interference RNA. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to examine MALAT1 expression in normal and silenced fibroblasts following irradiation with 60 mJ/cm² ultraviolet B (UVB) and an ELISA assay was used to identify matrix metalloproteinase-1 (MMP-1) content in the cellular supernatant. A β-galactosidase kit was applied to measure the number of senescent cells and a western blot assay was used to detect extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 phosphorylation levels. RT-qPCR was additionally used to detect changes in MALAT1 expression following suppression of UVB-induced reactive oxygen species (ROS) generation with N-acetyl-L-cysteine (NAC). Fibroblasts irradiated with 60 mJ/cm² UVB demonstrated increased MALAT1 expression, MMP-1 secretory volume and number of senescent cells, and greater levels of ERK, p38 and JNK phosphorylation. Following silencing of MALAT1 expression in photo-aged fibroblasts, decreases were observed in MMP-1 secretory volume, number of senescent cells and phosphorylation levels of ERK. NAC reduced ROS content, however, it did not affect MALAT1 expression. Therefore, it was concluded that MALAT1 may participate in UVB-induced photo-aging via regulation of the ERK/mitogen-activated protein kinase signaling pathway and UVB-induced MALAT1 expression is independent of ROS generation.