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Long noncoding RNAs (lncRNAs) are deeply involved in cancer development. We previously reported that DLEU1 (deleted in lymphocytic leukemia 1) is one of the lncRNAs overexpressed in oral squamous cell carcinoma (OSCC) cells, where it exhibits oncogenic activity. In the present study, we further clarified the molecular function of DLEU1 in the pathogenesis of OSCC. Chromatin immunoprecipitation-sequencing (ChIP-seq) analysis revealed that DLEU1 knockdown induced significant changes in the levels of histone H3 lysine 4 trimethylation (H3K4me3) and H3K27 acetylation (H3K27ac) in OSCC cells. Notably, DLEU1 knockdown suppressed levels of H3K4me3/ H3K27ac and expression of a number of interferon-stimulated genes (ISGs), including IFIT1, IFI6 and OAS1, while ectopic DLEU1 expression activated these genes. Western blot analysis and reporter assays suggested that DLEU1 upregulates ISGs through activation of JAK-STAT signaling in OSCC cells. Moreover, IFITM1, one of the ISGs induced by DLUE1, was frequently overexpressed in primary OSCC tumors, and its knockdown inhibited OSCC cell proliferation, migration and invasion. These findings suggest that DLEU1 exerts its oncogenic effects, at least in part, through activation of a series ISGs in OSCC cells.

Background/aim The role of tumour-infiltrating CD45Ro+ T-cells in oral squamous cell carcinoma (OSCC) is unclear. This study aimed to evaluate prognostic biomarkers for OSCC. Patients and methods We determined the density of tumour-infiltrating CD45Ro+ T cells in the parenchyma and stroma at the tumour centre (TCe) and invasive front (IF) and examined the association between the density of these cells and histopathological status in 142 patients. Results Five-year overall survival (OS) and recurrence-free survival were favourable in patients with high CD45Ro+ T-cell density in the TCe stroma. OS was favourable in patients with high CD45Ro+ T-cell density in the IF stroma. Stepwise Cox regression model analysis indicated that CD45Ro+ T-cells in the stroma of the IF and TCe were an independent prognostic factor for OS. Conclusion CD45Ro+ T-cells in the stroma of the IF and TCe play a role in cancer immune surveillance and may be a useful prognostic factor.

The CXCL12/CXCR4 axis plays a pivotal role in the progression of various malignancies, including oral squamous cell carcinoma (OSCC). In this study, we aimed to clarify the biological and clinical significance of CXCL12 in the tumor microenvironment of OSCCs.Publicly available single-cell RNA-sequencing (RNA-seq) datasets were used to analyze CXCL12 expression in head and neck squamous cell carcinomas (HNSCC). Immunohistochemical analysis of CXCL12, α-smooth muscle antigen (α-SMA), fibroblast activation protein (FAP) and CD8 was performed in a series of 47 surgically resected primary tongue OSCCs. Human skeletal muscle cells were co-cultured with or without OSCC cells, after which CXCL12 expression was analyzed using quantitative reverse-transcription PCR.Analysis of the RNA-seq data suggested CXCL12 is abundantly expressed in stromal cells within HNSCC tissue. Immunohistochemical analysis showed that in grade 1 primary OSCCs, CXCL12 is expressed in both tumor cells and muscle cells. By contrast, grade 3 tumors were characterized by disruption of muscle structure and reduced CXCL12 expression. Quantitative analysis of CXCL12-positive areas within tumors revealed that reduced CXCL12 expression correlated with poorer overall survival. Levels of CXCL12 expression tended to inversely correlate α-SMA expression and positively correlate with infiltration by CD8+ lymphocytes, though these relations did not reach statistical significance. CXCL12 was significantly upregulated in muscle cells co-cultured with OSCC cells.Our results suggest that tongue OSCC cells activate CXCL12 expression in muscle cells, which may contribute to tumor progression. However, CXCL12 is reduced in advanced OSCCs due to muscle tissue destruction.

Human leukocyte antigen (HLA) class Ⅰ molecules play a central role in anticancer immunity, but their prognostic value in oral squamous cell carcinoma (OSCC) remains unclear. We examined HLA class I expression in 2 distinct tumor compartments, namely, the tumor center and invasive front, and evaluated the association between its expression pattern and histopathological status in 137 cases with OSCC. Human leukocyte antigen class Ⅰ expression was graded semiquantitatively as high, low, and negative. At the invasive front of the tumor, HLA class I expression was high in 72 cases (52.6%), low in 44 cases (32.1%), and negative in 21 cases (15.3%). The HLA class I expression in the tumor center was high in 48 cases (35.0%), low in 58 cases (42.4%), and negative in 31 cases (22.6%). The 5‐year overall survival and disease‐specific survival rates were good in cases with high HLA class I expression at the invasive front; however, there was no significant difference in survival based on HLA class I expression in the tumor center. In addition, high HLA class I expression was correlated with high CD8+ T cell density, whereas negative HLA class I expression was correlated with low CD8+ T cell density at the invasive front. These results suggest that it is easier for CD8+ T cells to recognize presented peptides in the case of high HLA class Ⅰ expression at the tumor invasive front and could be a prognostic factor for OSCC., Human leukocyte antigen class Ⅰ expression at the tumor invasive front could be a useful prognostic factor for oral squamous cell carcinoma.

Objective Epithelial–mesenchymal transition (EMT) plays an important role in cancer invasion and metastasis induced by hypoxia. Here, we examined whether phosphorylation of GSK3-β via phosphoinositide 3-kinase (PI3 K)/Akt signaling is involved in enhancing the hypoxia-induced EMT in oral squamous cell carcinoma (OSCC). Study Design Experiments were performed in OSCC cell lines (HSC-2, HSC-3, HSC-4, SAS, and HO-1-U-1) under normoxic or hypoxic conditions. The EMT was assessed by Matrigel invasion assays and wound healing assays. OSCC cell lines (HSC-2 and HSC-4) overexpressing hypoxia-inducible factor (HIF)-1α were established to examine the effects of HIF-1α on EMT-related factors. Immunohistochemical staining was performed to examine phosphorylation of GSK3-β in 33 cases of tongue squamous cell carcinoma. Results Under hypoxic conditions, OSCC cell lines exhibited HIF-1α expression and showed evidence of the EMT. In cells overexpressing HIF-1α, the levels of phospho-Akt and phospho-GSK3-β were increased, resulting in induction of the EMT. Inhibition of GSK3-β phosphorylation suppressed these effects. Moreover, the intensity of pGSK3-β staining was significantly increased with cN stage and cTNM stage in patients with tongue squamous cell carcinoma. Conclusions Our data showed that the hypoxia-induced EMT in OSCC was enhanced by GSK3-β phosphorylation, suggesting that GSK3-β may be important in the invasion and metastasis of OSCC.

Background Tumor-infiltrating lymphocytes include tumor-reactive lymphocytes and regulatory T-cells. However, the prognostic value of tumor-infiltrating lymphocytes in oral squamous cell carcinoma (OSCC) remains unclear. Methods We used immunohistochemistry to evaluate the presence of tumor-infiltrating FoxP3⁺ T-cells and CTLA-4⁺ cells in four distinct histological compartments (tumor parenchyma and stroma at the tumor center, and parenchyma and stroma at the invasive front) and assessed the association between the prevalence of these cells and the histopathological status of 137 patients with OSCC. Results Five-year overall survival, disease-specific survival, and recurrence-free survival were favorable in patients with high numbers of FoxP3⁺ T-cells in the parenchyma of the invasive front. Recurrence-free survival and metastasis-free survival were decreased in patients with high numbers of CTLA-4⁺ cells in the parenchyma of the invasive front. Conclusions The presence of FoxP3⁺ T-cells in the parenchyma of the invasive front may be a useful prognostic factor. Our results indicate that FoxP3⁺ T-cells may exert site-specific anti-tumor effects but may not play an immunosuppressive role in OSCC. In addition, our results suggest that CTLA-4+ cells suppress the function of FoxP3+ T-cells and promote anti-tumor immunity in OSCC.

Recent studies have shown that long noncoding RNAs (lncRNAs) have pivotal roles in human malignancies, although their significance in oral squamous cell carcinoma (OSCC) is not fully understood. In the present study, we identified lncRNAs functionally associated with OSCC. By analyzing RNA-seq datasets obtained from primary head and neck squamous cell carcinoma (HNSCC), we identified 15 lncRNAs aberrantly expressed in cancer tissues. We then validated their expression in 18 OSCC cell lines using qRT-PCR and identified 6 lncRNAs frequently overexpressed in OSCC. Among those, we found that knocking down DLEU1 (deleted in lymphocytic leukemia 1) strongly suppressed OSCC cell proliferation. DLEU1 knockdown also suppressed migration, invasion, and xenograft formation by OSCC cells, which is suggestive of its oncogenic functionality. Microarray analysis revealed that DLEU1 knockdown significantly affects expression of a number of cancer-related genes in OSCC cells, including HAS3, CD44, and TP63, suggesting that DLEU1 regulates HA-CD44 signaling. Expression of DLEU1 was elevated in 71% of primary OSCC tissues, and high DLEU1 expression was associated with shorter overall survival of HNSCC patients. These data suggest that elevated DLEU1 expression contributes to OSCC development, and that DLEU1 may be a useful therapeutic target in OSCC.

Gene targeting using short interfering RNA (siRNA) has become a common strategy to explore gene function because of its prominent efficacy and specificity. For the application of siRNA technology to gene therapy, however, still more efficient transduction of siRNA into target cells is needed. In this study, we developed an adenoviral vector harboring a tandem-type siRNA expression unit, in which sense and antisense strands composing the siRNA duplex were separately transcribed by two human U6 promoters. Targeting survivin, an antiapoptotic molecule widely overexpressed in malignancies but not detected in terminally differentiated adult tissues, this type of adenoviral vector (Adv-siSurv) successfully exerted a gene knockdown effect and induced apoptosis in HeLa, U251, and MCF-7 cells. These cancer cells, once infected with Adv-siSurv, displayed remarkably attenuated growth potential, both in vitro and in vivo. Moreover, intratumoral injection of Adv-siSurv significantly suppressed tumor growth in a xenograft model using U251 glioma cells. This novel modality may be a promising tool for cancer therapy.

Interferon-gamma (IFN-gamma) induced cell death in five oral squamous cell carcinoma (SCC) lines. Cell death was specific to IFN-gamma treatment and did not occur with either IFN-alpha or TNF-alpha. IFN-gamma did not induce typical apoptotic phenotype in cells, such as morphological changes and DNA ladder formation. Caspase-3 was partially activated by IFN-gamma. Protein levels of molecular chaperones were examined in cells treated with IFN-gamma. Among these, levels of heat shock protein 27 (Hsp27) were specifically reduced upon IFN-gamma treatment of oral SCC cells. Recombinant clones overexpressing Hsp27 were more resistant to IFN-gamma-induced cell death than parent cells. Conversely, cells expressing a dominant-negative mutant of Hsp27, in which three serine residues (15, 78 and 82) were replaced by glycine, were hypersensitive to the effects of IFN-gamma and exhibited a typical apoptotic phenotype. Pretreatment of cells with IFN-gamma enhanced apoptotic cell death induced by cisplatin. Our data suggest that IFN-gamma suppresses Hsp27 expression in oral SCC cells and blocks the inhibitory effects of this molecular chaperone on apoptotic cell death. Moreover, IFN-gamma initiates the transition of oral SCC cells to the proapoptotic and/or aborted apoptotic state. Hsp27 plays a crucial role in the inhibition of apoptosis of oral SCC cells. Our findings highlight the importance of employing IFN-gamma in combination with certain anticancer drugs as treatments for oral cancer. We suggest that Hsp27 plays a significant role in the IFN-gamma-induced sensitization of oral SCC cells to anticancer drugs.

Background During tumor development, cells are exposed to a hypoxic microenvironment. Tumor hypoxia also has a profound influence on the sensitivity of cancer chemotherapy. The objective of this study was to investigate the mechanism of cisplatin (CDDP) resistance of oral squamous cell carcinoma (OSCC) cells under hypoxia by analyzing gene expression profiles to identify key genes and factors involved. Methods Cell viability was measured following culture of the cells in the presence or absence of CDDP, under normoxic or hypoxic conditions, using a CCK-8 assay. Analysis of the expression of HIF target genes in hypoxia-treated cells was performed using an HIF-regulated cDNA plate array. Changes in the mRNA expression of selected HIF target genes were analyzed using RT-PCR, and changes in the protein levels of these genes were analyzed by Western blotting. Tumor cell apoptosis was assessed by flow cytometry. Results The OSCC cell lines responded differently to CDDP under normoxic and hypoxic conditions. The expression of glucose transporter protein-1 (GLUT-1) was up-regulated in human squamous cell carcinoma of mouth (HSC-2) cells under hypoxia. Furthermore, there was little correlation between the cisplatin sensitivity of human squamous cell carcinoma of tongue (SAS) in normoxia and hypoxia. After GLUT-1 knockdown, CDDP treatment resulted in increased rates of apoptosis under hypoxia as compared with normoxia in cell lines HSC-2, Ca9-22, and SAS (P = 0.025). Conclusion The results of this study suggest that knockdown of GLUT-1 inhibits sensitization of oral squamous cells to CDDP during hypoxia in HSC-2, Ca9-22, and SAS cells.

Summary The purpose of this clinical trial was to assess the toxicity and efficacy of docetaxel plus nedaplatin induction chemotherapy in patients with locally advanced oral squamous cell carcinoma (OSCC). Twenty-one patients were enrolled in this phase I/II clinical study. The toxicities, response rates, and the maximum tolerated dose of nedaplatin that could be safely given preoperatively were assessed. Patients received escalating doses of nedaplatin (60, 70, 80, 90 mg/m 2 ) combined with a fixed dose of docetaxel (60 mg/m 2 ) on day one. Dose-limiting toxicity (DLT), grade 4 leukopenia lasting for two days or more, was seen in one patient at dose level 3; no other DLT was observed at any dose level. The overall response rate was 66.7%. The response rate was 100% at nedaplatin dose level 4, while that at dose level 1 was low (33.3%). Given these results, the recommended dose of nedaplatin in this regimen combined with fixed dose docetaxel (60 mg/m 2 ) was determined to be 90 mg/m 2 . Docetaxel 60 mg/m 2 plus nedaplatin 90 mg/m 2 induction chemotherapy can be recommended for patients with locally advanced oral squamous cell carcinoma. Based on these results, an early phase II clinical study using this dose level was conducted; docetaxel plus nedaplatin induction chemotherapy appears to be a useful regimen for the treatment of OSCC. A late phase II clinical study is warranted.

Objective. To compare the hematopoietic support provided by telomerized human mesenchymal stem cells (MSCs) and telomerized MSC-derived stromal cells. Methods. We transfected the human telomerase catalytic subunit (hTERT) gene into primary MSCs to establish hTERT-transduced MSCs (hTERT-MSCs). Stromal induction of hTERT-MSCs was performed by replacing the culture medium with Dexter-type culture medium. Hematopoietic support was examined by coculture with cord blood CD34 + cells. Results. The hTERT-MSCs were morphologically identical with the primary MSCs and expressed surface antigens including CD105, CD73, and CD166. hTERT-MSCs showed a similar doubling time as primary MSCs and continued to proliferate to over 80 population doublings (PD), although the primary MSCs underwent crisis in vitro at 16 PD. The osteogenic, chondrogenic, adipogenic, neurogenic, and stromal differentiation potential of hTERT-MSCs were maintained up to at least 40 PD. The degree of expansion of CD34 + cells and total number of colony-forming units in culture (CFU-C) upon 12-day coculture with the hTERT-MSC–derived stromal cells were nearly the same as those upon 12-day coculture with hTERT-MSCs (CD34, 33.0-fold±2.8-fold vs 36.1-fold±1.7-fold of the initial cell number; CFUs, 344.4-fold±62.5-fold vs 239.3-fold±87.0-fold; CFU-mix, 368.4-fold±113.7-fold vs 341.3-fold±234.3-fold). However, on day 18 of coculture, the number of cobblestone areas (CA) observed beneath the stromal cells was 15 times higher than that beneath hTERT-MSCs (CA, 146.9±54.6 vs 9.4±8.1, p Conclusion. Stromal induction of hTERT-MSCs exclusively enhanced the support of CA formation provided by hTERT-MSCs. Our human hTERT-MSCs will be useful for elucidating the mechanism of the formation of CAs.

Current clinical success rates of adenoviral vector (Adv)-based gene therapy of squamous cell carcinoma (SCC) of the head and neck remain unsatisfactory. A major problem with this approach is thought to be related to low Adv transduction efficiency due to weak expression of the adenovirus receptor, coxsackie-adenovirus receptor (CAR), in SCC. To improve the limited infectivity of Adv in oral SCC, we constructed mutated Adv incorporating the integrin-binding motif, RGD, in the HI loop of the fiber knob. The mutated Adv infected target cells through integrins commonly expressed in oral SCC. LacZ marker gene expression after infection with this mutated Adv (Adv-F/RGD) in oral SCC cell lines that showed reduced expression of CAR was approximately 5-10 times higher than that obtained with the parental Adv containing wild-type fiber knob (Adv-F/wt). In an in vitro study, transduction of oral cancer cell lines with Adv-F/RGD expressing human IL-2 (AxCAhIL2-F/RGD) resulted in greater production of cytokine than AxCAhIL2-F/wt infection. In an in vivo therapeutic xenograft model of oral SCC in nude mice, AxCAhIL2-F/RGD demonstrated antitumor effects superior to those of AxCAhIL2-F/wt. These data suggest that exploitation of genetically altered adenovirus vectors with integrin-binding motifs may offer significant improvements in oral SCC gene therapy.

BACKGROUND pRb2/p130 is one of the retinoblastoma (Rb) gene family and a suppressor oncogene. Immunohistochemically, the expression of pRb2/p130 was reported to be correlated inversely with the degree of malignancy in lung carcinoma and endometrial carcinoma. In the current study, the correlation between expression of pRb2/p130 and clinicopathologic factors in oral squamous cell carcinoma was investigated. METHODS One hundred twenty-two specimens from patients with oral squamous cell carcinoma were investigated by staining with a polyclonal antibody against pRb2/p130. The correlation between the expression of pRb2/p130 and various clinicopathologic factors was studied. RESULTS Positive staining for pRb2/p130 was observed in 61 of 122 cases (50.0%). pRb2/p130 expression was found to be correlated significantly with clinical stage (P = 0.050), cervical lymph node metastasis (P = 0.035), and tumor differentiation (P = 0.050). In the entire group a significantly reduced 5-year cumulative survival rate was observed in patients with pRb2/p130-negative tumors compared with patients whose tumors positively expressed pRb2/p130 (P = 0.0004). When tested with Cox proportional hazards regression analysis, the most significant independent prognostic factor for the entire group of 122 patients was found to be pRb2/p130 expression. CONCLUSIONS Expression of pRb2/p130 may be a good prognostic indicator in patients with oral squamous cell carcinoma and also may be utilized for the subclassification of tumors with the Grade 3 mode of carcinoma invasion. Cancer 2001;92:2117–25. © 2001 American Cancer Society.

We previously reported that pRb2/p130 gene, one of the Rb family members, was immunohistochemically abundantly expressed in well-differentiated oral squamous cell carcinomas, whereas in undifferentiated ones the expression was low. Oral malignant melanoma is extremely rare, however the prognosis is poor because it tends to locally invade tissue or metastasize and its biological behavior appears to be different from cutaneous malignant melanoma. The present study dealt with the expression of pRb2/p130, Rb, p53, and p16 in 13 cases of malignant melanoma of oral mucosa as revealed by immunohistochemical staining. The stage classification of the 13 patients was as follows; stage II: eight patients, stage III: three patients, and stage IV: two patients. pRb2/p130 was expressed in only two stage II-cases, neither of which have shown any evidence of recurrence or metastasis for over 14 years. Positive staining for Rb was found in three cases consisting of one stage II-case, one stage III-case, and one stage IV-case. p53 was expressed in two cases, one a stage II and the other a stage IV. Positive staining for p16 was found in seven cases consisting of four stage II-cases, two stage III-cases, and one stage IV-case. pRb2/p130 may be inversely correlated with the malignancy of oral malignant melanoma, but further study is needed.