Areca nut exposure increases secretion of tumor‐promoting cytokines in gingival fibroblasts that trigger DNA damage in oral keratinocytes

Abstract

Molecular crosstalk between cancer cells and fibroblasts has been an emerging hot issue in understanding carcinogenesis. As oral submucous fibrosis (OSF) is an inflammatory fibrotic disease that can potentially transform into squamous cell carcinoma, OSF has been considered to be an appropriate model for studying the role of fibroblasts during early stage carcinogenesis. In this sense, this study aims at investigating whether areca nut (AN)‐exposed fibroblasts cause DNA damage of epithelial cells. For this study, immortalized hNOF (hTERT‐hNOF) was used. We found that the levels of GRO‐α, IL‐6 and IL‐8 increased in AN‐exposed fibroblasts. Cytokine secretion was reduced by antioxidants in AN‐exposed fibroblasts. Increase in DNA double strand breaks (DSB) and 8‐oxoG FITC‐conjugate was observed in immortalized human oral keratinocytes (IHOK) after the treatment of cytokines or a conditioned medium derived from AN‐exposed fibroblasts. Cytokine expression and DNA damage were also detected in OSF tissues. The DNA damage was reduced by neutralizing cytokines or antioxidant treatment. Generation of reactive oxygen species (ROS) and DNA damage response, triggered by cytokines, were abolished when NADPH oxidase (NOX) 1 and 4 were silenced in IHOK, indicating that cytokine‐triggered DNA damage was caused by ROS generation through NOX1 and NOX4. Taken together, this study provided strong evidence that blocking ROS generation might be a rewarding approach for cancer prevention and intervention in OSF.

Growth‐regulated oncogene‐α from oral submucous fibrosis fibroblasts promotes malignant transformation of oral precancerous cells

“…The levels of GRO‐α, IL‐6, and IL‐8 were three most increased chemokines in OSF‐associated fibroblasts. This result is supported by a previous report of the cytokines increased in areca nut (AN)‐exposed fibroblasts and OSFs . The levels of IL‐6 and IL‐8 were also demonstrated to be significantly increased in the serum and saliva of patients with oral precancer lesions .…”

“…This result is supported by a previous report of the cytokines increased in areca nut (AN)-exposed fibroblasts and OSFs. 21 The levels of IL-6 and IL-8 were also demonstrated to be significantly increased in the serum and saliva of patients with oral precancer lesions. 22,23 Therefore, further longitudinal studies are needed to substantiate the utility of these cytokines as diagnostic or prognostic markers for oral cancer and precancer.…”

An Evaluation of Clinical and Histopathological Aspects of Patients with Oral Submucous Fibrosis in the Background of Oral Squamous Cell Carcinoma

“…Carcinogenesis in OSF is also attributed to several biochemical mechanisms [ 4 , 10 – 13 ]. The main contributors are described as arecoline-induced inactivation of tumor suppressor genes (P16) [ 13 ], damage to DNA (loss of heterozygosity and DNA double strand breakage) due to reactive oxygen species (ROS) [ 11 , 14 ], epithelial and extracellular matrix interactions, and copper-induced angiogenesis along with abnormal collagen formation [ 4 , 5 ]. Hypoxia, resulting from reduced vascularity, further promotes malignant transformation where hypoxia-induced factor – α (HIF- α ) is known to be a key factor [ 4 , 5 , 10 ].…”

Bcl‐2 is a prognostic marker and its silencing inhibits recurrence in ameloblastomas

“…Ten percent fetal bovine serum and 1% penicillin/streptomycin were supplemented to the F medium. A normal human epidermal keratinocytes cell line (HEK) was previously described (Illeperuma et al, ) and maintained in keratinocyte growth media with supplements and growth factors provided by KGM TM BulletKit TM (Lonza, Walkersville, MD). All cells were cultured at 37°C in a 5% CO 2 incubator.…”