MicroRNA-21 (miR-21) is overexpressed in a wide variety of cancers and has been related to cellular proliferation, apoptosis, and invasion; however, the function of miR-21 is unknown in oral tongue squamous cell carcinoma (OTSCC). The purpose of this study was to examine miR-21 expression in OTSCC, correlate it with clinicopathological factors, and investigate its contribution to OTSCC cell invasion. MiR-21 expression in 79 primary OTSCCs was evaluated using locked nucleic acid in situ hybridization, and correlation was examined with the clinicopathological factors. To determine the miR-21 target, we searched for molecular genes involved in tumor invasion using the commonly cited prediction program miRanda. In an OTSCC cell line, SCC25 cells, we further evaluated whether miR-21 contributes to cell invasiveness by blocking its expression with a specific knockdown LNA probe and confirmed the direct target by Matrigel invasion assay and Western blotting. MiR-21 overexpression was detected in 60 of 79 cases (75.9 %) and correlated with the pattern of invasion (P = 0.016). We selected DKK2 as a Wnt/antagonist involved in tumor invasion. MiR-21 overexpression was significantly correlated with the DKK2-/β-catenin- immunohistochemical phenotype. Knockdown of miR-21 significantly decreased the invasion potential of SCC25 cells with up-regulated DKK2. It was found that miR-21 is overexpressed and associated with tumor invasion in OTSCC, and that miR-21 promotes OTSCC cell invasion via the Wnt/β-catenin pathway by targeting DKK2 in vitro. These results suggest that miR-21 may be a potential therapeutic target for OTSCC treatment.

Although lipomas are common soft tissue tumors, few cases of lipoma or its variants have been reported in the oral cavity. We here described the clinical, histological, and immunohistochemical features of 24 cases of oral lipoma obtained from medical records at Nagasaki University Hospital between 1977 and 2010, and also retrospectively reviewed 603 cases of oral lipoma reported in the English literatures. The patients examined comprised 11 men and 13 women with a mean age of 59 years, ranging from 31 to 90 years. The main sites involved were the buccal mucosa (n = 9), followed by the tongue (n = 4), lip and retromolar area (n = 3), floor of the mouth (n = 2), and gingiva (n = 1). The mean tumor size was 2.0 cm, ranging from 0.2 to 5 cm. Histological analysis revealed 20 cases of lipoma, 2 cases of fibrolipoma, and one case each of intramuscular lipoma and spindle cell lipoma. Twenty-three cases were treated surgically while one case underwent biopsy and follow-up. Recurrence was not observed in any case. We reviewed the English literatures, and similar results were obtained. In immunohistochemical analysis, PCNA and ki-67 expression indices were higher in intramuscular lipoma cases than in its variants. Especially, it showed that a long time follow-up may be necessary in ki-67 positive cases.

Recent studies suggest that cancer stem cells may be responsible for tumorigenesis and contribute to some individuals' resistance to cancer therapy. Some studies demonstrate that side population (SP) cells isolated from diverse cancer cell lines harbor stem cell-like properties; however, there are few reports examining the role of SP cells in human oral cancer. To determine whether human oral cancer cell lines contain a SP cell fraction, we first isolated SP cells by fluorescence activated cell sorting, followed by culturing in serum-free medium (SFM) using the SCC25 tongue cancer cell line, so that SP cells were able to be propagated to maintain the CSC property. Differential expression profile of stem cell markers (ABCG2, Oct-4 and EpCAM) was examined by RT-PCR in either SP cells or non-SP cells. Growth inhibition by 5-FU was determined by the MTT assay. Clonogenic ability was evaluated by colony formation assay. SCC25 cells contained 0.23% SP cells. The fraction of SP cells was available to grow in SFM cultures. SP cells showed higher mRNA expression of stem cell markers (ABCG2, Oct-4 and EpCAM) as compared with non-SP cells. Moreover, SP cells demonstrated more drug resistance to 5-FU, as compared with non-SP cells. The clone formation efficiency of SP cells was significantly higher than non-SP cells at an equal cell number (P<0.01). We isolated cancer stem-like SP cells from an oral cancer cell line. SP cells possessed the characteristics of cancer stem cells, chemoresistance, and high proliferation ability. Further characterization of cancer stem-like SP cells may provide new insights for novel therapeutic targets.

The aim of this retrospective study was to assess the efficacy and safety of cetuximab therapy for patients with locally advanced (LA) and recurrent/metastatic (R/M) oral squamous cell carcinoma (OSCC), with a specific focus on distant metastases (DMs). Data from 21 patients with unresectable LA and R/M OSCC treated with cetuximab therapy in our department between December, 2012 and July, 2015 were reviewed. The endpoint was the time-to-progression and the assessments made were tumor response rate, progression-free survival (PFS), overall survival (OS) and safety. The overall response rate was 57.1%, with a complete response (CR) rate of 33.3%. The overall median PFS and OS were 5.5 and 8.0 months, respectively. For patients with DMs, the overall response rate was 60.0%, with a CR rate of 40.0%. The median PFS and OS were 3.8 and 5.8 months, respectively. In addition, improved 1-year OS was observed following approval of cetuximab, although the differences between the group of patients treated after that time and historical controls were not statistically significantly (P=0.246). Grade 3–4 adverse events included infusion reaction (4 cases), neutropenia, hypophosphatemia, upper gastrointestinal hemorrhage, liver toxicity and mucositis (1 case each). There was one cetuximab-related death due to interstitial pneumonia. An acne-like rash was observed in all cases, but no grade 3 or 4 rash was reported. Hypomagnesemia was observed in 10 cases. Our results suggest that cetuximab may display significant therapeutic efficacy in patients with unresectable LA and R/M OSCC, including those with DMs.

Abstract. The efficacy of neoadjuvant chemotherapy (NAC) is controversial, and no report supports NAC with a high evidence level. Recently, we showed that a deep surgical margin was resected very close to the tumor site in many NAC-treated oral squamous cell carcinoma patients, suggesting that NAC may lead to local recurrence and poor outcomes. The purpose of this study was to evaluate the effect of NAC on tumor local recurrence using cancer stem cell marker immunohistochemistry. We retrospectively analyzed 89 patients who underwent radical surgery for tongue cancer, and examined the effect of NAC on tumor local recurrence. Cancer stem cell marker (CD44v6 and ABCG2) expression was detected by immunohistochemistry. In our study, the local recurrence rate was 12.4%. CD44v6 and ABCG2 expression was significantly associated with regional lymph node metastasis, pattern of invasion, depth of invasion, perineural invasion and local recurrence, respectively. Tumor local recurrence was a significant independent predictive factor of the 5-year disease specific survival. CD44v6 or ABCG2 positivity in NAC-treated patients was significantly associated with tumor local recurrence. It was suggested that local recurrence in NAC-treated cases is associated with cancer stem-like cells. We propose that NAC leads to the selection and/or residue of more aggressive cancer stem-like cells.