Pretranscriptional Regulation of Tgf-β1 by PI Polyamide Prevents Scarring and Accelerates Wound Healing of the Cornea After Exposure to Alkali

Abstract

Corneal alkali burns are a serious clinical problem that often leads to permanent visual impairment. In this process, transforming growth factor (Tgf)-beta1 is upregulated and involved in the response to corneal injury and the process of corneal stromal scarring. To develop an efficient compound to inhibit Tgf-beta1 in the cornea, we designed GB1201, a pyrrole-imidazole (PI) polyamide targeting rat Tgf-beta1 gene promoter to the activator protein-1 (AP-1) binding site. GB1201 showed a high binding affinity to the target DNA sequence in the gel mobility shift and Biacore assays. GB1201 significantly inhibited the rat Tgf-beta1 gene promoter activity in HEK (human embryonic kidney) 293 cells in a concentration-dependent manner. Topically administrated GB1201 was distributed immediately to the nuclei of all cell layers of the cornea and remained for 24 hours. A corneal alkali burn model in rats was used to evaluate the therapeutic efficacy of GB1201. GB1201 suppressed the upregulation of Tgf-beta1 in the burned cornea, both in the mRNA and protein levels. Moreover, daily treatment with GB1201 for a week significantly improved the corneal tissue wound healing, reduced corneal stromal scarring, and prevented corneal haze formation. Our data suggest that PI polyamide may open new opportunities for therapeutic intervention in the treatment of chemically burned corneas.

Identification of Binding Targets of a Pyrrole-Imidazole Polyamide KR12 in the LS180 Colorectal Cancer Genome

“…From paired heterocyclic amide building blocks of pyrrole and imidazole, PIPs can distinguish G/C and A/T (T/A) pairs via DNA minor groove binding with Im/Py and Py/Py pairs, respectively, down to the precision of a single hydrogen bond between the bases. Chemical functionalization provides versatility in regulating biological events [9–15] such as cell reprogramming, NF- κ B-dependent gene transcription, retinal development, and the inhibition of specific biological targets [16, 17]. Nevertheless, as PIPs principally bind typically well less than 20 bp, the impact of binding at genomic locations other than the intended design site remains unclear to-date.…”

Targeting TGF-β Signaling for Therapeutic Gain

“…2; Table 1), including a pyrrole-imidazole polyamide drug that blocks transcription of the TGFB1 target gene (Yao et al 2009;Chen et al 2010;Matsuda et al 2011;Washio et al 2011;Igarashi et al 2015), antisense RNAs that target TGFB1 or TGFB2 mRNAs for degradation (Hau et al 2009;Vallieres 2009;Schlingensiepen et al 2011), antibodies against TGF-b ligands or receptors that block ligand -receptor engagement, and many small molecule ATP-mimetic TbRI kinase inhibitors (Fig. 2).…”

Modulation of the EMT/MET process by pyrrole–imidazole polyamide targeting human transforming growth factor-β1

“…We have already demonstrated that PI polyamide targeting TGF-β1 effectively attenuates progressive renal disease , stenosis of the carotid artery after angioplasty (Yao et al, 2009), alkali burn of the cornea (Chen et al, 2010), and hypertrophic scars (Washio et al, 2011). PI polyamides targeted to TGF-β1 may thus be a potent gene silencer at the transcription level.…”