Yasuyuki Michi

Comprehensive keratin profiling reveals different histopathogenesis of keratocystic odontogenic tumor and orthokeratinized odontogenic cyst

Keratocystic odontogenic tumor is a cystic lesion that behaves more aggressively than other jaw cysts. One of its characteristic histologic features is a parakeratinized uniform layer of lining epithelium. A jaw cyst lined with orthokeratinized epithelium is called an orthokeratinized odontogenic cyst. These keratinized jaw cysts are thought to be separate entities, although their histopathogenesis has not been fully assessed. To better understand these lesions, we performed comprehensive immunohistochemical profiling of the keratin expression of each. Orthokeratinized odontogenic cysts expressed keratin 1, keratin 2, keratin 10, and loricrin, suggesting differentiation toward normal epidermis. Keratocystic odontogenic tumors expressed keratin 4, keratin 13, keratin 17, and keratin 19, which is a unique expression pattern reminiscent of a mucosal squamous epithelium and an epithelial appendage. In neonatal rat tooth germ, cells strongly positive for keratin 17 and keratin 19 were observed, specifically in the dental lamina, implying the origin of keratocystic odontogenic tumor. GLI2, a downstream effector of hedgehog signaling, was significantly expressed in keratocystic odontogenic tumor and basal cell carcinoma, accompanied with robust expression of keratin 17, mammalian target of rapamycin, and BCL2. The expression of these GLI2- or keratin 17-related factors was not significantly observed in orthokeratinized odontogenic cysts. These findings provide evidence to support the viewpoint that keratocystic odontogenic tumor and orthokeratinized odontogenic cyst are separate entities, and furthermore suggest their characteristic histology, pathogenesis, and biological behaviors.

CXCL2 synthesized by oral squamous cell carcinoma is involved in cancer-associated bone destruction

To explore the mechanism of bone destruction associated with oral cancer, we identified factors that stimulate osteoclastic bone resorption in oral squamous cell carcinoma. Two clonal cell lines, HSC3-C13 and HSC3-C17, were isolated from the maternal oral cancer cell line, HSC3. The conditioned medium from HSC3-C13 cells showed the highest induction of Rankl expression in the mouse stromal cell lines ST2 and UAMS-32 as compared to that in maternal HSC3 cells and HSC3-C17 cells, which showed similar activity. The conditioned medium from HSC3-C13 cells significantly increased the number of osteoclasts in a co-culture with mouse bone marrow cells and UAMS-32 cells. Xenograft tumors generated from these clonal cell lines into the periosteal region of the parietal bone in athymic mice showed that HSC3-C13 cells caused extensive bone destruction and a significant increase in osteoclast numbers as compared to HSC3-C17 cells. Gene expression was compared between HSC3-C13 and HSC3-C17 cells by using microarray analysis, which showed that CXCL2 gene was highly expressed in HSC3-C13 cells as compared to HSC3-C17 cells. Immunohistochemical staining revealed the localization of CXCL2 in human oral squamous cell carcinomas. The increase in osteoclast numbers induced by the HSC3-C13-conditioned medium was dose-dependently inhibited by addition of anti-human CXCL2-neutralizing antibody in a co-culture system. Recombinant CXCL2 increased the expression of Rankl in UAMS-32 cells. These results indicate that CXCL2 is involved in bone destruction induced by oral cancer. This is the first report showing the role of CXCL2 in cancer-associated bone destruction.

Unusual expression of red fluorescence at M phase induced by anti-microtubule agents in HeLa cells expressing the fluorescent ubiquitination-based cell cycle indicator (Fucci)

Plinabulin (NPI-2358) is a novel microtubule-depolymerizing agent. In HeLa cells, plinabulin arrests the cell-cycle at M phase and subsequently induces mitotic catastrophe. To better understand the effects on this compound on the cell-cycle, we used the fluorescent ubiquitination-based cell cycle indicator (Fucci), which normally enables G1 and S/G2/M cells to emit red and green fluorescence, respectively. When HeLa-Fucci cells were treated with 50 nM plinabulin, cells began to fluoresce both green and red in an unusual pattern; most cells exhibited the new pattern after 24 h of treatment. X-irradiation efficiently induced G2 arrest in plinabulin-treated cells and significantly retarded the emergence of the unusual pattern, suggesting that entering M phase is essential for induction of the pattern. By simultaneously visualizing chromosomes with GFP-histone H2B, we established that the pattern emerges after nuclear envelope breakdown but before metaphase. Pedigree assay revealed a significant relationship between the unusual expression and mitotic catastrophe. Nocodazole, KPU-133 (a more potent derivative of plinabulin), and paclitaxel also exerted similar effects. From these data, we conclude that the unusual pattern may be associated with dysregulation of late M phase-specific E3 ligase activity and mitotic catastrophe following treatment with anti-microtubule agents.

Complications and Outcome of Free Flap Transfers for Oral and Maxillofacial Reconstruction: Analysis of 213 Cases

Abstract Microvascular free flap transfers have become a preferred reconstructive technique; however, rare complications may still prove devastating. This study reviewed 213 consecutive freetissue transfers in order to assess the incidence and causes of complications in patients undergoing microvascular free flap reconstruction in the oral and maxillofacial region. In most cases, reconstruction was undertaken after resection of a malignant tumor. The flap donor sites were the radial forearm (n=111), rectus abdominis (n=88), scapula (n=13), and latissimus dorsi (n=1). The superior thyroid artery and the external jugular vein were commonly used as recipient vessels for anastomosis. The overall flap success rate was 99%. There were 7 cases of postoperative vascular thrombosis (6 venous and 1 arterial), constituting 3.3% of the entire series. Five flaps were salvaged, representing a 71.4% successful salvage rate in cases of vascular complications. Most of the successful salvage attempts were made within 24 hours of the end of the initial operation, and the successful salvage rate for re-exploration was 100%. Finally, the total flap loss rate was 0.9% and the partial flap loss rate was 2.3%. We conclude that early re-exploration should be the first choice for management of vascular compromised flaps. Complications at the donor site occurred in 17 cases (8.0%), the most common complication of which was partial skin graft loss after harvesting a radial forearm flap (n=10; 9.0%). Recipient and donor site morbidity was limited and considered acceptable.

Acerogenin A, a natural compound isolated from Acer nikoense Maxim, stimulates osteoblast differentiation through bone morphogenetic protein action

We investigated the effects of acerogenin A, a natural compound isolated from Acer nikoense Maxim, on osteoblast differentiation by using osteoblastic cells. Acerogenin A stimulated the cell proliferation of MC3T3-E1 osteoblastic cells and RD-C6 osteoblastic cells (Runx2-deficient cell line). It also increased alkaline phosphatase activity in MC3T3-E1 and RD-C6 cells and calvarial osteoblastic cells isolated from the calvariae of newborn mice. Acerogenin A also increased the expression of mRNAs related to osteoblast differentiation, including Osteocalcin, Osterix and Runx2 in MC3T3-E1 cells and primary osteoblasts: it also stimulated Osteocalcin and Osterix mRNA expression in RD-C6 cells. The acerogenin A treatment for 3days increased Bmp-2, Bmp-4, and Bmp-7 mRNA expression levels in MC3T3-E1 cells. Adding noggin, a BMP specific-antagonist, inhibited the acerogenin A-induced increase in the Osteocalcin, Osterix and Runx2 mRNA expression levels. These results indicated that acerogenin A stimulates osteoblast differentiation through BMP action, which is mediated by Runx2-dependent and Runx2-independent pathways.

Clinical study on mandibular fracture after marginal resection of the mandible.

OBJECTIVES Postoperative mandibular fracture (PMF) after marginal resection (MR) of the mandible remains an unresolved issue, and it has been reported that at least 10 mm of postoperative mandibular body height (PMBH) is required to prevent PMF. This study evaluated the clinical, physical, and structural risk factors for PMF in MR patients and determined appropriate preventive measures for PMF. STUDY DESIGN This retrospective study included 44 patients with lower gingival carcinoma who underwent MR. PMF occurred in four of these patients. Thirteen associated factors identified from medical records and radiographs were statistically analyzed. RESULTS Mandibular body height (MBH) preservation ratio originally evaluated as less than 0.3, more than 20 remaining teeth after surgery, and inferior alveolar canal (IAC) exposure were significant risk factors for PMF. Prostheses and number of remaining teeth were also correlated with PMF. CONCLUSIONS The preserved mandibular bone should be reinforced in patients with an MBH preservation ratio of less than 0.3, more than 20 remaining teeth after surgery, and intraoperative IAC exposure. Patients with prostheses are at an increased risk of PMF compared with those without because of stable occlusion and a strong occlusal force. Our novel findings provide useful reference standards for PMF prevention in MR patients.

Clinical usefulness of 2-deoxy-2-[18F] fluoro-d-glucose-positron emission tomography/computed tomography for assessing early oral squamous cell carcinoma (cT1-2N0M0)

Background Positron emission tomography with 2-deoxy-2-[18F] fluoro-d-glucose integrated with computed tomography (FDG-PET/CT) is a useful method to evaluate patients with oral squamous cell carcinoma (OSCC). However, the prognostic significance of FDG-PET/CT for assessing early OSCC remains unclear. Methods Pretreatment FDG-PET/CT of 205 consecutive patients (125 men, 80 women, mean age 59.7 year old) with early OSCC (cT1-2N0M0) between June 2010 and December 2014 were retrospectively analyzed. FDG avidity in primary lesions was assessed by visual interpretation. Thereafter, maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were measured in primary lesions. The relationship between each parameter and recurrence free survival (RFS) was assessed using the log-rank test. The performance of FDG-PET/CT for diagnosing metastatic lesions and synchronous cancer was also assessed. Results During the follow-up period (mean 32.9 months), 43 patients developed recurrences (21.0%). Patients with visually positive FDG uptake in primary lesions showed significantly shorter RFS than the others (63.0 months vs. 52.9 months, P = 0.005). In those patients, greater SUVmax, MTV, and TLG did not significantly predict shorter RFS. The sensitivity and specificity of FDG-PET/CT for cervical nodal metastases detection were 32.3% and 77.6%, respectively. FDG-PET/CT detected eight synchronous cancers (3.9%) and overlooked six synchronous cancers (2.9%). Conclusions Although its utility for detecting cervical nodal metastases and synchronous cancers is limited, FDG-PET/CT is a potentially prognostic indicator in early OSCC.

First signs of late-presenting cervical lymph node metastasis in oral cancers during follow-up

One of the most important prognostic factors in oral squamous cell carcinoma (OSCC) is the presence of lymph node metastasis. Therefore, the early detection of late-presenting cervical lymph node metastasis is important. Although many studies have assessed diagnostic modalities for detecting metastatic cervical lymph nodes, no study has evaluated the process, especially first signs, for detecting late-presenting cervical lymph node metastasis. A retrospective analysis comparing methods for detecting the first signs of late-presenting lymph node metastasis was performed. A total of 65 OSCC patients were assessed. These patients were identified retrospectively as having presented late metastasis during follow-up after initial treatment with curative intent. The findings of four detection methods were analyzed: palpation, ultrasonography, computed tomography, and subjective symptoms. The numbers of cases identified by each method were as follows: palpation, 31 (47.7%); ultrasonography, 17 (26.1%); computed tomography, 12 (18.5%); and subjective symptoms, 5 (7.7%). Palpation played a major role in the discovery of late-presenting lymph node metastasis. In contrast, metastatic lymph nodes were detected by other methods in about half of the cases. The results suggest a possible stratification of the various methods used for metastatic lymph node detection, depending on the characteristics of individual cases.

A Neuroendocrine Tumor in the Maxilla

A 39-year-old man was referred to the Department of Oral and Maxillofacial Surgery at the Graduate School of Tokyo Medical and Dental University Hospital, Tokyo, Japan. He had begun to have painless swelling of the left side of the maxilla 3 months earlier, and the swelling had recently grown noticeably larger. The facial configuration was symmetric on clinical examination, but an intraoral examination showed a hard, well-defined, elastic swelling with a smooth surface on the hard palate. The lesion measured 38 35 20 mm (Fig 1). Contrast-enhanced computed tomography (CT) depicted a mass lesion of 35 mm in diameter expanding to the left sinus. The lesion manifested as an irregular slight enhancement. No metastatic images were observed in the head, neck, or lung. Contrast-enhanced magnetic resonance imaging showed an indistinctly bordered lesion measuring 41 31 28 mm extending from the left maxillary alveolar process in the left palate. This lesion showed intermediate signal intensity on the T1-weighted image and homogeneous high signal intensity on the T2-weighted image (Fig 2). During the patient’s first visit, our clinical impression was suspected salivary tumor of the left maxilla. One week fter the first visit, a small biopsy specimen was collected rom the left hard palatal swelling. Then, at 2 weeks after he first visit, the lesion was preliminarily diagnosed as a uspected synovial sarcoma or undifferentiated carcinoma f the left maxilla based on the first interim biopsy report. About 4 weeks after the first visit, evidence of rapid umor growth prompted us to initiate urgent treatment of he suspected sarcoma. The patient was hospitalized and cheduled for a therapeutic operation. Chemotherapy was dministered for 3 weeks (5-fluorouracil, 250 mg/fr, 5 fr/w, 4,100 mg) after cannulation of the left superficial temporal rtery for delivering 5-fluorouracil through the artery into

Detection of Second Primary Malignancies of the Esophagus and Hypophraynx in Oral Squamous Cell Carcinoma Patients: Detection of second primary malignancies

To assess the usefulness of modified esophagogastroduodenoscopy (EGD) for the detection of second primary malignancies of the esophagus or hypopharynx in patients with oral squamous cell carcinoma and determine the association between the oral lesion subsite and esophageal or hypopharyngeal lesion occurrence.