Expression of interferon regulatory factor 5 is regulated by the Sp1 transcription factor

The Reciprocal Interaction Between LncRNA CCAT1 and miR-375-3p Contribute to the Downregulation of IRF5 Gene Expression by Solasonine in HepG2 Human Hepatocellular Carcinoma Cells

Solasonine (SS), a natural glycoalkaloid component, has been shown to have potent inhibitory activity and cytotoxicity against many cancer types. However, the precise mechanisms underlying this, particularly in hepatocellular carcinoma (HCC) are poorly understood. In this study, we showed that SS inhibited growth of HCC cells. Mechanistically, we observed that SS increased the expression of miR-375-3p, whereas reducing levels of long non-coding RNAs (lncRNAs) CCAT1 was noticed in HepG2 HCC and other cells. In addition, we found that SS repressed transcription factors, SP1 and interferon regulatory factor 5 (IRF5), protein expressions. There was a reciprocal interaction among miR-375-3p, CCAT1, and SP1. Moreover, SS inhibited IRF5 promoter activity, which was not observed in cells transfected with excessive expressed SP1 vectors. Interestingly, exogenously expressed IRF5 was shown to reverse expressions of SS-inhibited CCAT1 and induced-miR-375-3p; and neutralized SS-inhibited growth of HCC cells. Similar results were also found in vivo mouse model. Collectively, our results show that SS inhibits HepG2 HCC growth through the reciprocal regulation between the miR-375-3p and lncRNA CCAT1, and this results in transcription factor SP1-mediated reduction of IRF5 expression. The regulations and interactions among miR-375-3p, CCAT1, SP1, and IRF5 axis unveil a novel molecular mechanism underlying the anti-HCC growth by SS. IRF5 may be a potential target for treatment of HCC.

Transcription factor E2F1 positively regulates interferon regulatory factor 5 expression in non-small cell lung cancer

Purpose

Lung cancer is the most common malignant tumor in the world, and its incidence and mortality are very high. This study focuses on the mechanism of non-small cell lung cancer to find new therapeutic targets.

Methods

We used RT-PCR and Western blot to verify the linear relationship between E2F1 and IRF5 in normal lung tissue and lung cancer tissues. Secondly, we used overexpression and knock down E2F1 in cell lines to detect the expression of IRF5. The prime enzyme reporter plasmid verified that E2F1 binds to the core promoter region of IRF5; finally, CHIP experiments demonstrated that E2F1 binds directly to IRF5.

Results

We verified that E2F1 and IRF5 are decreased in patient tissues, and there is a strong linear relationship between E2F1 and IRF5. Secondly, we used overexpression of E2F1 or E2F1 siRNA transfected into HCC827 cells and found that E2F1 positively regulates the activity of the IRF5 promoter and the mRNA level of IRF5. Finally, the results of a chromatin immunoprecipitation assay demonstrated that E2F1 bound to the promoter region of IRF5 in vitro. These results suggested that the E2F1 transcription factor is the primary determinant for activating the basal transcription of the IRF5.

Conclusion

The transcription factor E2F1 positively regulates IRF5 in non-small cell lung cancer.

Potential role of the HOXD8 transcription factor in cisplatin resistance and tumour metastasis in advanced epithelial ovarian cancer

Few studies have examined the potential transcription factor (TF) simultaneously associated with cisplatin resistance and metastasis in ovarian cancer. To assess a related mechanism, a 345-channel protein/DNA array and transcriptional activity ELISA were performed to compare the TF activities in the cisplatin-sensitive SKOV3 and cisplatin-resistant SKOV3-DDP cells and in HO-8910 and the homologous highly metastatic HO-8910PM cells. In SKOV3-DDP vs. SKOV3 cells, 43 TFs were up-regulated, while 31 were down-regulated. In HO-8910PM vs. HO-8910 cells, 13 TFs were up-regulated, while 18 were down-regulated. In these two models, 4 TFs (HOXD8(1), HOXD8(2), RB, RFX1/2/3) were simultaneously up-regulated, and 9 TFs (SRE, FKHR, Angiotensinogen ANG-IRE, Pax2, CD28RC/NF-IL2B, HLF, CPE, CBFB and c-Ets-1) were down-regulated. HOXD8 mRNA and protein expression levels measured by reverse transcription polymerase chain reaction and ELISA, respectively, were significantly higher in SKOV3-DDP and HO-8910PM than in their corresponding cell lines (both p < 0.05). In 52 cases of different ovarian disease, the patients with recurrent and cisplatin-resistant ovarian cancer had higher expression levels of HOXD8 than patients with primary malignant tumours (p = 0.018, p = 0.001) or benign tumours (p = 0.001, p < 0.001). Taken together, these results suggest that HOXD8 is potentially associated with both cisplatin resistance and metastasis in advanced ovarian cancer.

IRF5 is elevated in childhood-onset SLE and regulated by histone acetyltransferase and histone deacetylase inhibitors

Interferon regulatory factor 5 (IRF5) plays a critical role in the induction of type I interferon, proinflammatory cytokines and chemokines, and participates in the pathogenesis of autoimmune diseases such as systemic lupus erythematosus (SLE). However, the relationship between IRF5 and childhood-onset SLE remains elusive. In the present study, we demonstrated that levels of mRNA expression of IRF5, IFN-α, and Sp1 were significantly increased in childhood-onset SLE, as seen on quantitative real-time PCR, and the expression of Sp1 and IFN-α was positively correlated with IRF5. In addition to being used as antitumor drugs, a number of histone deacetylase inhibitors (HDACi) display potent anti-inflammatory properties; however, their effects on IRF5 expression remain unclear. In this study, we identified that HDACi trichostatin A (TSA) and histone acetyltransferase (HAT)-p300 downregulated IRF5 promoter activity, mRNA expression, and protein level, whereas the HAT-p300/CBP-associated factor had no effect. Moreover, TSA inhibited the production of TNF-α and IL-6 in differentiated THP-1cells. Furthermore, chromatin immunoprecipitation assays revealed that TSA inhibited DNA binding of Sp1, RNA polymerase II, HDAC3, and p300 to the core promoter region of IRF5. Our results suggest that HDACi may have therapeutic potential in patients with autoimmune diseases such as SLE through repression of IRF5 expression.