No abstract

Most oral cancers are oral squamous cell carcinoma (OSCC). The anatomical features of OSCC have been histochemically evaluated with hematoxylin and eosin. However, the border between the cancer and stromal regions is unclear and large portions of the cancer and stromal regions are resected in surgery. To reduce the resected area and maintain oral function, a new method of diagnosis is needed. In this study, we tried to clearly distinguish the border on the basis of biomolecule distributions visualized by imaging mass spectrometry (IMS). In the IMS dataset, eleven signals were significantly different in intensity (p < 0.01) between the cancer and stromal regions. Two signals at m/z 770.5 and m/z 846.6 were distributed in each region, and a clear border was revealed. Tandem mass spectrometric (MS/MS) analysis identified these signals as phosphatidylcholine (PC) (16:0/16:1) at m/z 770.5 in the cancer region and PC (18:1/20:4) at m/z 846.6 in the stromal region. Moreover, the distribution of PC species containing arachidonic acid in the stromal region suggests that lymphocytes accumulated in response to the inflammation caused by cancer invasion. In conclusion, the cancer and stromal regions of OSCCs were clearly distinguished by use of these PC species and IMS analysis, and this molecular identification can provide important information to elucidate the mechanism of cancer invasion.

Overexpression of epidermal growth factor receptor (EGFR) has been found in various epithelial malignancies, including head and neck squamous cell carcinoma (HNSCC), and is associated with increased tumor growth, metastasis, resistance to chemotherapeutic agents and poor prognosis. As such, EGFR is a potential target for antitumor therapy and several EGFR inhibitors have been investigated in preclinical or clinical settings. In the present study, we used small interfering RNA (siRNA) to downregulate EGFR expression while evaluating the effect of EGFR siRNA on cell proliferation, and the combined effects with cisplatin, 5-fluorouracil (5-FU) and docetaxel in HNSCC. Furthermore, HNSCC xenografts were treated with EGFR siRNA alone or in combination with cisplatin, and tumor growth was examined. EGFR expression, proliferation, angiogenesis and apoptosis index were evaluated by immunohistochemistry. The results showed that EGFR siRNA efficiently downregulated EGFR expression and inhibited cell growth of HNSCC. Treatment with EGFR siRNA in combination with cisplatin, 5-FU and docetaxel enhanced chemosensitivity with a significant increase in apoptosis. EGFR siRNA delivered by atelocollagen enhanced the antitumor effect of cisplatin in the HNSCC xenograft model. These cumulative results suggest that EGFR siRNA combined with cisplatin, 5-FU and docetaxel may be a feasible strategy to enhance the effects of chemotherapy in patients with HNSCC.

Periodontal disease is a serious dental problem because it does not heal naturally and leads to tooth loss. In periodontal disease, inflammation at periodontal tissue is thought as predominant, and its effect against tooth itself remains unclear. In this study, we applied matrix-assisted laser desorption/ionization imaging mass spectrometry (IMS) to teeth for the first time. By comparing anatomical structure of tooth affected with periodontal disease with normal ones, we analyzed traces of the disease on tooth. We found signals characteristic of enamel, dentin, and dental pulp, respectively, in mass spectra obtained from normal teeth. Ion images reconstructed using these signals showed anatomical structures of the tooth clearly. Next, we performed IMS upon teeth of periodontal disease. Overall characteristic of the mass spectrum appeared similar to normal ones. However, ion images reconstructed using signals from the tooth of periodontal disease revealed loss of periodontal ligament visualized together with dental pulp in normal teeth. Moreover, ion image clearly depicted an accumulation of signal at m/z 496.3 at root surface. Such an accumulation that cannot be examined only from mass spectrum was revealed by utilization of IMS. Recent studies about inflammation revealed that the signal at m/z 496.3 reflects lyso-phosphatidylcholine (LPC). Infiltration of the signal is statistically significant, and its intensity profile exhibited the influence has reached deeply into the tooth. This suggests that influence of periodontal disease is not only inflammation of periodontal tissue but also infiltration of LPC to root surface, and therefore, anti-inflammatory treatment is required besides conventional treatments.