Background Phosphoactivation of a DNA damage response molecule checkpoint kinase 2 (pChk2) may be a marker of oral epithelial cells that have entered the precancerous and squamous cell carcinoma (SCC) stages. to SCC (control groups) by immunohistochemical analysis. Included in both groups were lesions with histologically confirmed dysplasia and those that lacked histologic evidence of atypia. Results Subjects with pChk2-positive but histology-negative (for atypia) lesions had an 8.6 times higher risk of developing SCC compared with those with pChk2-negative and histology-negative lesions. Overall, the presence of detectable pChk2 staining was able to identify lesions at risk of developing SCC SNS-032 cost within 3 years with a sensitivity of 85.2%, specificity of 74.2%, and predictive accuracy of 78.2% (odds ratio, 19.9; 95% confidence interval, 7.3-55.5). Conclusion This is the first study to include histologically nonatypical cases in the analysis of a putative biomarker for oral precancerous lesions. Our data show that pChk2 merits further investigation as a promising biomarker that can discriminate those lesions at risk for developing SCC, regardless of histologic evidence for atypia. Introduction An estimated 400,000 people worldwide are newly diagnosed with oral squamous cell carcinoma (SCC) annually, which accounts for 5% of all cancers in men and 2% in women (1). Oral SCC poses a threat to public health SNS-032 cost as it is associated with a 50% mean 5-year survival rate (1). Due to the poor survival rate once malignant transformation occurs, considerable focus is now placed on early detection of precancerous Rabbit Polyclonal to CKLF4 oral lesions. The most common clinical SNS-032 cost presentation of oral precancerous lesion is those of leukoplakia, erythroplakias, and erythroleukoplakia. Upon biopsy, 80% of leuko/erythroplakias are nondysplastic lesions that show epithelial hyperplasia and/or hyperkeratosis. Seventeen percent are dysplastic lesions, and the remaining 3% are SCC (2, 3). However, a small portion of nondysplastic lesions progress to SCC within 3 to 6 years (4). These most likely represent the earliest form of precancerous lesion biopsied before atypical histomorphologic alterations have occurred. Clearly, a method that selectively identifies true pre-malignant lesions among the clinical leuko/erythroplakias would allow improved control of oral SCC by means of early detection. During the normal cellular response to DNA damage, the checkpoint kinase 2 (Chk2) protein is phosphorylated at threonine residue 68 to generate an enzymatically active isoform of the protein, hereafter called pChk2. Remarkably, a recent study has shown that pChk2 isoform, as well as other activated DNA damage factors, is expressed at exceptionally high levels in pre-malignant cells and continues to be expressed in cells that have undergone overt malignant transformation (5-8). This phenomenon presumably reflects induction of the DNA-damage response during the initial steps of carcinogenesis. In any event, if pChk2 expression precedes the morphologic changes of dysplastic cells and, thus, confers higher sensitivity than biopsy-based histo-logic assessment, it may then serve as an ideal marker for oral precancerous lesions and SCCs. The leading etiologic factors implicated in oral cancer, such as tobacco, alcohol, and chronic inflammation, SNS-032 cost are thought to promote DNA damage either by direct DNA modification or by abnormalities of the cell cycle checkpoint machinery. One of the well-characterized molecular pathways for oral carcinogenesis involves activation of the epidermal growth factor receptor, which in turn initiates the ras/ mitogen-activated protein SNS-032 cost kinase and PI3K/Akt-signaling cascades (9, 10). The genetic alteration and constitutive activation of oncogenic pathways can elicit unscheduled progression into the cell cycle, leading to DNA damage checkpoint activation either directly or indirectly via formation of DNA double-strand breaks (5, 6, 8). The cellular response to DNA damage is largely coordinated by the proteins ATM and ATR, two related serine/threonine kinases that are triggered early in the damage response and phosphorylate several key effectors of the response, including the Chk2 kinase (5-8). Therefore, in normal cells, pChk2 can serve as an important cellular defense against malignant progression by inducing downstream signaling pathways that halt cell cycle progression, facilitate DNA restoration, or promote apoptosis (7, 8). Despite the above findings, the possible use of pChk2 manifestation status as an early indicator of oral cancer risk has not been previously investigated. Accurate variation between oral premalignant and malignant lesions from medical leuko/erythroplakias would confer opportunities for early treatment. As an initial step in the pursuit of a reliable biomarker for SCC risk assessment with clinical energy, we examined pChk2 manifestation status in oral lesions using a retrospective cohort design. Materials and Methods Patients and Cells Samples A retrospective cohort of 145 individuals with an initial biopsied oral leukoplakias or erythroplakias that resulted in a histologic analysis of dysplasia or additional nondysplastic diagnosis, but not SCC, were included in the study. Specific histologic analysis for those or one nondysplastic lesion included epithelial hyperplasia, hyperkeratosis, mucosal swelling, candidiasis, and oral lichen planus. The individuals (= 48) who formulated SCC at a later time in the same.