miR-200c Modulates the Pathogenesis of Radiation-Induced Oral Mucositis

Abstract

Radiation-induced oral mucositis (RIOM) is one of the most common side effects of radiotherapy in cancer patients, especially in almost all head and neck cancer patients. It presents as severe pain and ulceration. The development of RIOM is composed of five stages: initiation, primary damage response, signal amplification, ulceration, and healing. However, the key regulators involved in the RIOM pathogenesis remain largely unknown. In this study, we reveal a novel role of miR-200c, a member of the miR-200 family, in modulating RIOM pathogenesis. Using a mouse model mimicking RIOM, we found that the miR-200 family numbers (miR-141, miR-200a, miR-200b, and miR-200c) except miR-429 were significantly induced during the RIOM formation. Besides, in RIOM mice, miR-200c expression level was also increased dramatically in the normal human keratinocytes (NHKs) after irradiation. Knockdown of miR-200c expression with miR-200c-3p-shRNA significantly reduced senescence phenotype and enhanced cell proliferation in NHKs after irradiation. The generation of reactive oxygen species (ROS) and p47 enzyme involved in ROS production was increased after irradiation but both were markedly reduced in NHKs by miR-200c inhibition. Knockdown of miR-200c expression in NHKs increased DNA double-strand break repair after irradiation compared with control NHKs. Furthermore, miR-200c inhibition repressed the production of proinflammatory cytokines (TGF-β, TNF-α, and IL-1α) via inhibiting NF-κB and Smad2 activation in NHKs exposed to IR. Additionally, miR-200c inhibition promoted NHK migration and increased the expression of molecules that regulate epithelial to mesenchymal transition, including Snail, Vimentin, Zeb1, and Bmi-1. These results not only identify the key role of miR-200c in the pathogenesis of RIOM but also provide a novel therapeutic target to treat RIOM.

Quercetin Prevents Radiation-Induced Oral Mucositis by Upregulating BMI-1

“…Our previous study demonstrated that BMI-1 was obviously reduced in RIOM mouse tongues at both the mRNA and protein expression levels [ 14 ]. BMI-1 plays a significant role in cellular radiosensitivity and has radioprotective effects on NHKs by silencing oxidase expression and enhancing DNA repair [ 18 ].…”

“…The isolation of primary NHKs from foreskin and the culture of NHKs were described previously [ 14 ]. To obtain NHK/control and NHK/shBMI-1 cells, we infected NHKs (passage 1) with lentivirus carrying a control vector (GCSIL-GFP) or BMI-1 shRNA (GCSIL-GFP-sh BMI-1 ) purchased from GeneChem (Shanghai).…”

“…Immunoblotting was performed as described in our previous study [ 14 ]. Briefly, mouse tongues and NHKs were treated with RIPA buffer.…”

Emerging Role of MicroRNA-200 Family in Dentistry

“…The miR-200 family numbers, including miR-200a, miR-200b, miR-200c, and miR-141, were all induced during the formation of radiation-induced oral mucositis in an animal model [ 65 ]. Tao et al demonstrated that the expression of miR-200c was increased dramatically in the normal human keratinocytes after irradiation.…”

“…They showed that miR-200c was involved in the regulation of cell migration, expression of EMT factors, DNA double-strand break repair, and generation of reactive oxygen species (ROS). Moreover, their results demonstrated that miR-200c participated in the production of proinflammatory cytokines through suppression of NF-κB and Smad2 activation [ 65 ].…”