Objectives: Osteonecrosis of the jaw (ONJ) is a potentially severe adverse effect of bisphosphonates (BP). Although the risk of ONJ increases with increasing duration of BP treatment, there are currently no reliable estimates of the ONJ time to onset (TTO). The objective of this study was to estimate the TTO and associated risk factors in BP-treated patients.
Subjects and methods:Retrospective analysis of data from 22 secondary care centres in 7 countries relevant to 349 patients who developed BP-related ONJ between 2004 and 2012.
Results:The median (95%CI) TTO was 6.0 years in patients treated with alendronate (n = 88) and 2.2 years in those treated with zoledronate (n = 218). Multivariable Cox regression showed that dentoalveolar surgery was inversely associated, and the use of antiangiogenics directly associated, with the TTO in cancer patients treated with zoledronate.
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Conclusions:The incidence of ONJ increases with the duration of BP therapy, with notable differences observed with respect to BP type and potency, route of administration and underlying disease. When data are stratified by BP type, a time of 6.0 and 2.2 years of oral alendronate of intravenous zoledronate therapy, respectively, is required for 50% of patients to develop ONJ. After stratification by disease, a time of 5.3 and 2.2 years of BP therapy is required for 50% of patients with osteoporosis and cancer, respectively, to develop ONJ. These findings have significant implications for the design of future clinical studies and the development of risk reduction strategies aimed at either assessing or modulating the risk of ONJ associated with BP.
Cisplatin (CDDP) is widely used to treat oral squamous cell carcinoma (OSCC), however, many patients exhibit acquired drug resistance. Yes-associated protein (YAP) is a transcriptional co-activator of the Hippo pathway that regulates organ size and promotes cell proliferation. YAP overexpression correlates with epithelial-mesenchymal transition and nodal metastasis, resulting in anti-tubulin drug resistance. Whether YAP overexpression is the cause of CDDP resistance in cancer cells is unclear, therefore, we investigated the correlation between YAP expression and CDDP sensitivity. We established three CDDP-resistant cell lines (OSC-19-R, SCCKN-R and HSC-3-R) from the OSCC parental cell lines. We also examined the expression levels of ATP7B, GST-π and ERCC1, which are strongly associated with CDDP resistance, and Hippo pathway-related proteins by western blotting. Using immunocytochemistry, we examined the cellular localization of YAP. Additionally, following knockdown of YAP using short interfering RNAs (siRNAs), we analyzed changes in sensitivity to CDDP. Compared with parental OSC-19 cells, OSC-19-R cells were obviously larger. Expression levels of YAP were not significantly different between OSC-19 and OSC-19-R. However, expression levels of phosphorylated YAP in OSC-19-R were decreased. We observed translocation of YAP from the cytoplasm to the nucleus in OSC-19-R cells. Knockdown of YAP using siRNAs revealed that sensitivity to CDDP was significantly increased. Translocation of YAP correlated with the acquisition of CDDP resistance. YAP could be a new therapeutic target for the treatment of patients with cancer that are resistant to CDDP.
Expression of COX-2 and DNA-Topo IIalpha were related to lymph node metastasis, cell proliferative activity, and overall 5-year survival rate in oral carcinoma. These enzymes may therefore be valuable diagnostic and prognostic indices in oral carcinoma.
Summary
Bisphosphonate-related osteonecrosis of the jaw (BRONJ), characterized by refractory bone exposure, has recently emerged as a serious side effect of bisphosphonate (BPs) treatment. We discuss novel insights that may help to improve the efficacy of BRONJ treatment and prevention. Our report highlights the following: (1) The presence of exposed bone in patients taking BPs does not necessarily reflect BRONJ, and diagnoses of oral ulceration with bone sequestration and malignancy must be excluded. (2) Osteonecrosis type of BRONJ is difficult to avoid using preventive dental measures alone. However, as with osteomyelitis type of BRONJ, preventive dental measures are indispensable for reducing the risk of secondary infection and disease progression. (3) The importance of tooth extraction as a risk factor for BRONJ among patients taking BPs has been overstated, particularly when they are administered at low doses. Delaying tooth extraction may increase the risk for the onset and progression of osteomyelitic BRONJ. (4) In patients taking low doses of BPs, dental implant surgery is not necessarily contraindicated if there are no other risk factors, such as combined use of corticosteroids or concomitant diabetes. However, the risk of BRONJ due to peri-implantitis must be explained when obtaining patient consent.
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