Stromal myofibroblasts and malignant transformation in a 4NQO rat tongue carcinogenesis model

4-nitroquinoline 1-oxide-induced oral epithelial lesions exhibit time- and stage-dependent changes in the tumor immune microenvironment

Oral tongue squamous cell carcinoma (OTSCC) is the most common cancer of the oral cavity and is associated with high morbidity due to local invasion and lymph node metastasis. Tumor infiltrating lymphocytes (TILs) are associated with good prognosis in oral cancer patients and dictate response to treatment. Ectopic sites for immune activation in tumors, known as tertiary lymphoid structures (TLS), and tumor-associated high-endothelial venules (TA-HEVs), which are specialized lymphocyte recruiting vessels, are associated with a favorable prognosis in OSCC. Why only some tumors support the development of TLS and HEVs is poorly understood. In the current study we explored the infiltration of lymphocyte subsets and the development of TLS and HEVs in oral epithelial lesions using the 4-nitroquinoline 1-oxide (4NQO)-induced mouse model of oral carcinogenesis. We found that the immune response to 4NQO-induced oral epithelial lesions was dominated by T cell subsets. The number of T cells (CD4+, FoxP3+, and CD8+), B cells (B220+) and PNAd+ HEVs increased from the earliest to the latest endpoints. All the immune markers increased with the severity of the dysplasia, while the number of HEVs and B cells further increased in SCCs. HEVs were present already in early-stage lesions, while TLS did not develop at any timepoint. This suggests that the 4NQO model is applicable to study the dynamics of the tumor immune microenvironment at early phases of oral cancer development, including the regulation of TA-HEVs in OTSCC.

Voltage-Dependent Anion Channel 1 Expression in Oral Malignant and Premalignant Lesions

BACKGROUND

The voltage-dependent anion channel 1 protein (VDAC1) plays a role in cellular metabolism and survival. It was found to be down or upregulated (overexpressed) in different malignancies but it was never studied in application to oral lesions. The purpose of this study was to retrospectively evaluate the expression of VDAC1 in biopsies of oral premalignant, malignant, and malignancy-neutral lesions and to examine the possible correlations to their clinicopathological parameters.

MATERIALS AND METHODS

103 biopsies including 49 oral squamous cell carcinoma, 33 epithelial dysplasia, and 21 fibrous hyperplasia samples were immunohistochemically stained with anti-VDAC1 antibodies for semi-quantitative evaluation. The antibody detection was performed with 3,3'-diaminobenzidine (DAB). The clinicopathological information was examined for possible correlations with VDAC1.

RESULTS

VDAC1 expression was lower in oral squamous cell carcinoma 0.63 ± 0.40 and in oral epithelial dysplasia 0.61 ± 0.36 biopsies compared to fibrous hyperplasia biopsies 1.45 ± 0.28 (p < 0.01 for both; Kruskal-Wallis test).

CONCLUSION

Oral squamous cell carcinoma and epithelial dysplasia tissues demonstrated decreased VDAC1 protein expression if compared to fibrous hyperplasia samples, but were not different from each other, suggesting that the involvement of VDAC1 in oral carcinogenesis is an early stage event, regulating cells to live or die.

4-nitroquinoline-1-oxide (4NQO) induced oral carcinogenesis: A systematic literature review

OBJECTIVE

Based on a critical review of published studies, we aimed to develop a good practice guide for using 4-nitroquinoline-1-oxide (4NQO) as an inducer of oral carcinogenesis in Wistar rats.

DESIGN

A systematic search was performed on Medline Ovid, PubMed, Embase, Web of Science, and Scopus databases. The SYRCLE's risk of bias tool was used to assess the quality of the studies.

RESULTS

Thirty-five articles met the selection criteria; 22 (62.9%) of them administered 4NQO systemically in drinking water, with a mean concentration of 30.2 ppm (SD±15.9) and during a mean period of 20.8 (SD±7.8) weeks. The other 13 (37.1%) studies performed topical applications of 4NQO painting the oral mucosa of the animals three times a week (100%) with a mean period of administration of 16.8 (SD±7.0) weeks. Different 4NQO concentrations used for other periods achieved significant tumor development. Most studies didn't perform quantitative clinical analysis, and the histopathological diagnosis/grading criteria varied considerably.

CONCLUSIONS

A poor description of solution care, adverse effects, and the number of losses were observed, and the reporting of these features needs to be improved. Suggestions to guide the development of future research are provided.

Tacrolimus inhibits oral carcinogenesis through cell cycle control

Tacrolimus (TAC, FK506) is a major calcineurin inhibitor and has been commonly used in treatments of patients with organ transplants and immune diseases. Moreover, tacrolimus is recommended by the treatment guidelines for oral potentially malignant disorders (OPMDs) such as oral lichen planus (OLP). However, whether tacrolimus increases the risk of cancer remains controversial. We observed that in a 4-Nitroquinoline N-oxide (4NQO)-induced oral carcinogenesis model, tacrolimus treatment was associated with a significantly lower ratio of cancer formation (52.94% vs. 90%) and a lower proportion of Ki67 and proliferation cell nuclear antigen (PCNA) -positive cells in lesion areas (P < 0.001). Liver, kidney, and lung functions of rats and the tumor immune microenvironment of the tongue were not affected. These observations suggest that tacrolimus blocked oral carcinogenesis through epithelial cell proliferation inhibition, independent of its immunosuppressive effects. As a processing factor, tacrolimus decreased tumor formation and cell proliferation in different stages of oral squamous cell carcinoma (OSCC) progression in vivo and in vitro. Furthermore, we investigated effects on the cell cycle and expression of related proteins. Tacrolimus induced G1/S phase arrest and significantly downregulated the expression of cyclinD1, cyclinE1, and c-Myc. These results suggest that tacrolimus induces G1/S phase arrest via inhibition of cyclinD1, cyclinE1, and c-Myc expression and retards oral cell carcinogenesis in vitro and in vivo. Thus, application of tacrolimus is a safe therapeutic strategy for treating OPMDs.

Cancer-Associated Fibroblast Density, Prognostic Characteristics, and Recurrence in Head and Neck Squamous Cell Carcinoma: A Meta-Analysis

Introduction

The progression and clinical course of head and neck squamous cell carcinoma (HNSCC) relies on complex interactions between cancer and stromal cells in the tumor microenvironment (TME). Among the most abundant of these stromal cells are cancer-associated fibroblasts (CAFs). While their contribution to tumor progression is widely acknowledged, and various CAF-targeted treatments are under development, the relationship between CAF density and the clinicopathologic course of HNSCC has not been clearly defined. Here we examine the published evidence investigating the relationship of cancer-associated fibroblasts to local recurrence and indicators of prognostic significance in HNSCC.

Methods

We conducted a meta-analysis of existing publications that compare the relationship between CAF density, local recurrence, and clinically significant pathologic criteria of disease development (T stage, nodal positivity, clinical stage, vascular invasion, perineural invasion, Ki67 expression, and differentiation). Thirteen studies met the selection criteria, providing a total study population of 926 patients. Forest plots and risk ratios were generated to illustrate overall relationships.

Results

Higher CAF density within the tumor microenvironment is associated with advanced T stage, nodal infiltration, clinical stage, vascular invasion, perineural invasion, Ki67 expression, and differentiation (p <0.05). High CAF density is also associated with increased rates of local recurrence (p <0.001).

Conclusions

Across multiple studies, increased CAF density is correlated with histopathological criteria of poor prognosis in HNSCC. These findings highlight that CAFs may play a pivotal role in HNSCC development and progression. Staining for CAFs may represent a valuable addition to current pathologic analysis and help to guide prognosis and treatment. Understanding the mechanisms by which CAFs reciprocally interact with cancer cells will be crucial for optimization of TME-focused treatment of HNSCC.

The Histopathology of Oral Cancer Pain in a Mouse Model and a Human Cohort

Oral cancer patients often have severe, chronic, and mechanically induced pain at the site of the primary cancer. Oral cancer pain is initiated and maintained in the cancer microenvironment and attributed to release of mediators that sensitize primary sensory nerves. This study was designed to investigate the histopathology associated with painful oral cancers in a preclinical model. The relationship of pain scores with pathologic variables was also investigated in a cohort of 72 oral cancer patients. Wild-type mice were exposed to the carcinogen, 4-nitroquinoline 1-oxide (4NQO). Nociceptive (pain) behavior was measured with the dolognawmeter, an operant device and assay for measuring functional and mechanical allodynia. Lesions developed on the tongues and esophagi of the 4NQO-treated animals and included hyperkeratoses, papillomas, dysplasias, and cancers. Papillomas included lesions with benign and dysplastic pathological features. Two histologic subtypes of squamous cell carcinomas (SCCs) were identified-SCCs with exophytic and invasive components associated with papillary lesions (pSCCs) and invasive SCCs without exophytic histology (iSCCs). Only the pSCC subtype of tongue cancer was associated with nociceptive behavior. Increased tumor size was associated with greater nociceptive behavior in the mouse model and more pain experienced by oral cancer patients. In addition, depth of invasion was associated with patient-reported pain. The pSCC histology identifies 4NQO-induced tongue cancers that are expected to be enriched for expression and release of nociceptive mediators.

Ki67, CD105 and α-smooth muscle actin expression in disease progression model of oral submucous fibrosis

AIM

The aim of this study was to investigate the expression of Ki67, CD105 and α-smooth muscle actin (α-SMA) expression in oral submucous fibrosis (OSF) and oral squamous cell carcinoma in the background of OSF (OSCC-SMF).

METHODS

The study was carried out on paraffin-embedded tissues of 30 normal oral mucosa (NOM), 50 OSF cases and 105 OSCC-SMF. The immunohistochemistry was carried out to evaluate the expression of Ki67, CD105 and α-SMA antigen.

RESULTS

Ki67 labelling index (LI), CD105 and α-SMA expression showed increasing trend from NOM, low-risk epithelial dysplasia (LRED), high-risk epithelial dysplasia (HRED), well-differentiated squamous cell carcinoma (WDSCC), moderately differentiated squamous cell carcinoma to poorly differentiated squamous cell carcinoma. However, there was no significant difference of α-SMA expression between HRED and WDSCC. In OSCC-SMF, Ki67 LI, CD105 and α-SMA were significantly higher in advanced clinical TNM stage, metastasis and less than 3 years patient survival as compared with early clinical TNM stage, non-metastasis and 3 years or more patient survival.

CONCLUSION

Ki67 LI, α-SMA and CD105 expression alone or together correspond with the disease progression model of SMF. Hence, expression of these markers can be used as a predictive marker of clinical outcome of OSCC-SMF.

MTA3-SOX2 Module Regulates Cancer Stemness and Contributes to Clinical Outcomes of Tongue Carcinoma

Cancer cell plasticity plays critical roles in both tumorigenesis and tumor progression. Metastasis-associated protein 3 (MTA3), a component of the nucleosome remodeling and histone deacetylase (NuRD) complex and multi-effect coregulator, can serve as a tumor suppressor in many cancer types. However, the role of MTA3 in tongue squamous cell cancer (TSCC) remains unclear although it is the most prevalent head and neck cancer and often with poor prognosis. By analyzing both published datasets and clinical specimens, we found that the level of MTA3 was lower in TSCC compared to normal tongue tissues. Data from gene set enrichment analysis (GSEA) also indicated that MTA3 was inversely correlated with cancer stemness. In addition, the levels of MTA3 in both samples from TSCC patients and TSCC cell lines were negatively correlated with SOX2, a key regulator of the plasticity of cancer stem cells (CSCs). We also found that SOX2 played an indispensable role in MTA3-mediated CSC repression. Using the mouse model mimicking human TSCC we demonstrated that the levels of MTA3 and SOX2 decreased and increased, respectively, during the process of tumorigenesis and progression. Finally, we showed that the patients in the MTA3^low/SOX2^high group had the worst prognosis suggesting that MTA3^low/SOX2^high can serve as an independent prognostic factor for TSCC patients. Altogether, our data suggest that MTA3 is capable of repressing TSCC CSC properties and tumor growth through downregulating SOX2 and MTA3^low/SOX2^high might be a potential prognostic factor for TSCC patients.

Immunohistochemical Expression of Myofibroblasts Using Alpha-smooth Muscle Actin (SMA) to Assess the Aggressive Potential of Various Clinical Subtypes of Ameloblastoma

Objective:

Ameloblastoma is a rare odontogenic neoplasm with high recurrence rates if improperly treated. If left untreated (or is treated inadequately), it can cause substantial morbidity, disfigurement, and even death. Hence, there is a need to explore the stromal cells too, which might play an important role in assessing its aggressive behavior and may help to predict the recurrence of different clinical variants of ameloblastoma. Myofibroblasts (MFs) are such cells which have been studied in various lesions.

Materials and Methods:

This retrospective study involved archival tissues of ameloblastoma. Among a total of 40 cases, 12 cases of SMA (solid multicystic ameloblastoma), 10 cases of unicystic ameloblastoma (UA), 8 cases of desmoplastic ameloblastoma, and 10 cases of oral squamous cell carcinoma were selected as control. Immunohistochemical staining with anti-alpha-smooth muscle actin antibody was done. Interpretation of ten examined fields was counted by three observers.

Results:

Significant difference in the number of MFs in SMA and UA and desmoplastic ameloblastoma and UA (P < 0.05) was found. However, there was no statistically significant difference in MFs of SMA and desmoplastic ameloblastomas (P > 0.05). In addition, there was no statistically significant difference in the staining intensity between the three variants (P > 0.05).

Conclusion:

A significant correlation was obtained between the number of MF in all the three clinical variants, i.e., SMA, UA, and desmoplastic ameloblastoma (P = 0.02), which is the unique feature of the study.

Identification and characterization of a highly metastatic epithelial cancer cell line from rat tongue cancer

OBJECTIVES

Tongue squamous cell carcinoma (TSCC) is a clinically devastating disease. However, most established TSCC cell lines currently show undesirable malignant behaviours. The purpose of this study is to establish a highly metastatic TSCC cell line to serve as a useful tool for basic research.

MATERIALS AND METHODS

TSCCs were induced by 4-nitroquinoline-1-oxide (4NQO) in Sprague-Dawley rats. Tumor cells were obtained from the cancer tissues by primary culture and were then purified by an in vitro invasion assay and a limiting dilution assay. The growth rate, cell cycle distribution, apoptotic rate, tumorigenicity and distant metastatic phenotypes of the rat tongue cancer cells were fully investigated and characterized.

RESULTS

To date, the rat tongue cancer cell line, named Rca-T, has been continuously cultured in vitro for over 210 passages and exhibit a long spindle-shaped morphology, adherent growth, and a stable epithelial phenotype. The population doubling time of Rca-T cells is 23.35 h. Approximately 39.8% of these cells are in S phase, and the apoptosis rate of Rca-T cells is 7.46%. Furthermore, in immunodeficient nude mice, both the xenograft rate and the incidence of experimental lung metastasis are 100%. The in vitro assays further reveal the highly malignant and epithelial-mesenchymal transition-like properties of Rca-T cells.

CONCLUSION

In this study, the tumorigenic and highly distant metastatic TSCC cell line Rca-T was established. The malignant features of this cell line, especially its metastatic potential, will enable a wealth of functional studies on the molecular mechanisms of TSCC metastasis in the future.

Combination of structural and vascular optical coherence tomography for differentiating oral lesions of mice in different carcinogenesis stages

Differentiating between early malignancy and benign lesions in oral cavities is difficult using current optical tools. As has been shown in previous studies, microvascular changes in squamous epithelium can be regarded as a key marker for diagnosis. We propose the combination of structural and vascular optical coherence tomography (OCT) imaging for the investigation of disease related changes. Progressive thickness changes of epithelium and the destruction of underlying lamina propria was observed during cancer development in a 4- nitroquinoline-1-oxide (4NQO) mouse model. At the same time, microvascular changes in hyperplasia, dysplasia, carcinoma in situ and advanced cancer were observed. Findings from OCT imaging were compared with histology.

Modulation of IL-1β reprogrammes the tumor microenvironment to interrupt oral carcinogenesis

Head and neck squamous cell carcinoma (HNSCC) development is a multistage process includes the normal, dysplasia and squamous cell carcinoma (SCC) stages. Recently, increasing evidence has suggested that the tumor microenvironment (TME) is an integral part of malignant transformation. Exploring certain key node genes in TME for future intervention in dysplasia to interrupt oral carcinogenesis was the primary goal of this research. To achieve this goal, systems biology approaches were first applied to the epithelia and fibroblasts collected at sequential stages in a 4-nitroquinoline-1-oxide (4NQO) - induced rat oral carcinogenesis model. Through bioinformatics network construction, IL-1β was identified as one of the key node genes in TME during carcinogenesis. Immunohistochemical staining of human and rat samples demonstrated that IL-1β expression patterns were parallel to the stages of malignant transformation. Silencing IL-1β with lentivirus-delivered shRNA significantly inhibited oral squamous cell carcinoma cell growth both in vivo and in vitro. Based on these findings, we hypothesized that IL-1β may be a chemoprevention target in TME during oral carcinogenesis. Therefore, we targeted IL-1 in the TME by oral mucosal injection of an IL-1 receptor antagonist in 4NQO rats. The results demonstrated that targeting IL-1 could interrupt oral carcinogenesis by reprogramming the TME.

Overexpression of Bcl-2, SOCS 1, 3 and Cdh 1, 2 are associated with the early neoplasic changes in modified 4-nitroquinoline 1-oxide-induced murine oral cancer model

BACKGROUND

The objective was to assess histopathological changes and the expression of proliferating cell nuclear antigen (PCNA), Bcl-2, suppressor of cytokine signaling (SOCS) 1 and 3, Vimentin, TWIST1, and Cdh 1 and 2 in early stages of experimental oral carcinogenesis process using a shorter period of exposure to 4-nitroquinoline oxide (4-NQO) model.

METHODS

In this study, 20 rats were divided into control group (n = 10), sacrificed on the first day of the experiment, and experimental group (n = 10) treated with 50 ppm of 4-NQO solution dissolved in drinking water for 8 and 12 weeks. The histological sections were stained with H&E or subjected to immunohistochemistry for detecting PCNA, Bcl-2, SOCS 1 and 3, and STAT 3. Some specimens were used for verification of Vimentin expression, Cdh 1, Cdh 2, and TWIST1 by RT-qPCR.

RESULTS

At both 8 and 12 weeks, morphological changes occurred mainly in the posterior portion of the tongue and were limited to the epithelial tissue, including moderate to severe dysplasia at 8 weeks, and severe dysplasia with exacerbation of atypical cells at 12 weeks. Expression of SOCS 1 and 3 increased from 8 to 12 weeks (P < 0.05), whereas STAT 3 expression was reduced mainly at 12 weeks (P < 0.05) in comparison with the control group. The expression of all epithelial-mesenchymal transition markers (EMT) was increased after 12 weeks, reaching statistical significance (P < 0.05) for Cdh 1 and 2.

CONCLUSIONS

Together, the results suggested that overexpression of Bcl-2, SOCS 1 and 3, and Cdh 1 and 2 is associated with the early neoplasic changes in modified 4-nitroquinoline 1-oxide-induced murine oral cancer model.

Myofibroblast presence in apparently normal mucosa adjacent to oral squamous cell carcinoma associated with chronic tobacco/areca nut use: evidence for field cancerization

OBJECTIVE

Myofibroblasts are primary cellular components of activated tumor stroma, associated with poor prognosis in oral squamous cell carcinoma (OSCC). However, their role in field cancerization has not been addressed. This study aims to evaluate the presence of myofibroblasts in patient-matched histologically normal mucosa adjacent to oral squamous cell carcinoma (HNMAOSCC) and OSCC tissues.

MATERIALS AND METHODS

Fifty patient-matched tissues of OSCC and HNMAOSCC associated with chronic areca nut/tobacco use were subjected to immunohistochemistry using α-SMA for detection of myofibroblasts. Normal oral mucosa (n = 15) were stained as controls.

RESULTS

The number of α-SMA stained myofibroblasts in OSCC and HNMAOSCC were significantly increased as compared to that of the normal controls (p < 0.001). Further, a significant correlation was established for the presence of myofibroblasts in the stroma of OSCC and HNMAOSCC.

CONCLUSIONS

Myofibroblasts are an early stromal change in the HNMAOSCC, highlighting the possible role of myofibroblasts as likely mediators for field cancerization and their potential use as a field effect marker.

Stromal myofibroblasts in squamous cell carcinoma of the tongue in young patients - a multicenter collaborative study

OBJECTIVE

The purpose of this study was to evaluate the presence of myofibroblasts, frequently associated with a more aggressive neoplastic behavior, in oral tongue squamous cell carcinoma (TSCC) of young patients and to compare with the distribution observed in older patients.

STUDY DESIGN

Tumor samples from 29 patients younger than 40 years old affected by TSCC were retrieved and investigated for the presence of stromal myofibroblasts by immunohistochemical reactions against α smooth muscle actin, and the results obtained were compared to TSCC cases affecting older patients.

RESULTS

No positive reaction could be found in the stromal areas devoid of neoplastic tissue, whereas myofibroblasts were present in 58.6% of the lesions in young patients and in 75.9% of the older ones. No significant difference was found when comparing the invasive front and the overall stroma of both groups, and no correlation could be obtained with stromal α smooth muscle actin expression, higher tumor grades or clinical stage (P > .05).

CONCLUSION

There was no significant difference between the presence of stromal myofibroblasts of TSCC affecting young and old individuals.

Myofibroblasts in oral lesions: A review

Myofibroblasts (MFs) are modified fibroblasts that express features of smooth muscle differentiation and were first observed in granulation tissue during wound healing. These cells play a key role in physiologic and pathologic processes like wound healing and tumorigenesis. The presence of MFs has been reported in normal oral tissues and pathologic conditions like reactive lesions, benign tumors, locally aggressive tumors and malignancies affecting the oral cavity. This article briefly reviews the important hallmarks related to the discovery, characterization and tissue distribution of MFs in oral health and disease.

Use of high frequency ultrasound to monitor cervical lymph node alterations in mice

Cervical lymph node evaluation by clinical ultrasound is a non-invasive procedure used in diagnosing nodal status, and when combined with fine-needle aspiration cytology (FNAC), provides an effective method to assess nodal pathologies. Development of high-frequency ultrasound (HF US) allows real-time monitoring of lymph node alterations in animal models. While HF US is frequently used in animal models of tumor biology, use of HF US for studying cervical lymph nodes alterations associated with murine models of head and neck cancer, or any other model of lymphadenopathy, is lacking. Here we utilize HF US to monitor cervical lymph nodes changes in mice following exposure to the oral cancer-inducing carcinogen 4-nitroquinoline-1-oxide (4-NQO) and in mice with systemic autoimmunity. 4-NQO induces tumors within the mouse oral cavity as early as 19 wks that recapitulate HNSCC. Monitoring of cervical (mandibular) lymph nodes by gray scale and power Doppler sonography revealed changes in lymph node size eight weeks after 4-NQO treatment, prior to tumor formation. 4-NQO causes changes in cervical node blood flow resulting from oral tumor progression. Histological evaluation indicated that the early 4-NQO induced changes in lymph node volume were due to specific hyperproliferation of T-cell enriched zones in the paracortex. We also show that HF US can be used to perform image-guided fine needle aspirate (FNA) biopsies on mice with enlarged mandibular lymph nodes due to genetic mutation of Fas ligand (Fasl). Collectively these studies indicate that HF US is an effective technique for the non-invasive study of cervical lymph node alterations in live mouse models of oral cancer and other mouse models containing cervical lymphadenopathy.

α-Smooth muscle actin-positive myofibroblasts, in association with epithelial-mesenchymal transition and lymphogenesis, is a critical prognostic parameter in patients with oral tongue squamous cell carcinoma

BACKGROUND

α-Smooth muscle actin (α-SMA)-positive myofibroblasts play a pivotal role in progression and metastasis of solid carcinomas. Epithelial-mesenchymal transition (EMT) of cancer cells and lymphogenesis of tumor microenvironment are the important events in tumor metastasis. This study aimed to investigate the relationship between the expression of myofibroblasts marker, α-SMA, and clinicopathological features, EMT, lymphogenesis, and prognostic status in oral tongue squamous cell carcinoma (OTSCC).

METHODS

Immunohistochemisty was used to detect α-SMA expression in 50 OTSCCs. EMT and lymphogenesis were also identified by immunostaining with N-cadherin, vimentin, and lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1).

RESULTS

There was a significant correlation respectively between the α-SMA (P = 0.002), vimentin (P < 0.001), N-cadherin (P = 0.025) expression and cervical lymph node metastasis of OTSCC. Carcinomas with α-SMA (P = 0.001), vimentin (P = 0.003), and N-cadherin (P = 0.012) expression were more advanced in terms of tumor-node-metastases status. Univariate analysis showed that pathologic node status (P < 0.001), α-SMA (P = 0.001), and vimentin expression (P = 0.044) was significantly associated with overall survival time, but multivariate analysis just showed the α-SMA expression (P = 0.008) and pathologic node status (P = 0.003) was independently predictive of prognosis. Furthermore, statistical analysis showed significant correlation between α-SMA expression and vimentin (P = 0.037), N-cadherin (P = 0.019), or LYVE-1 positive vessel count (P = 0.041).

CONCLUSION

Our results indicate that α-SMA-positive myofibroblasts have important impacts on cancer progression, metastasis, and survival prognosis of patients with OTSCC. The functions of α-SMA-positive myofibroblasts in OTSCC may be associated with promoting EMT of tumor cells and lymphogenesis of metastasis microenvironment.

Myofibroblasts and their relationship with oral squamous cell carcinoma

Myofibroblasts are hybrid-phenotype differentiated cells in between fibroblasts and smooth muscle cells. Due to their contractile features and ability to synthesize extracellular matrix components, cytokines, proteases, and proangiogenic factors, myofibroblasts have been implicated in the pathogenesis of fibrocontractive diseases and in the progression of many tumors, including oral squamous cell carcinoma (SCC).

Objective

To perform a literature review on the origin of myofibroblasts, their main morpho-physiological and immunohistochemical aspects, and to discuss the correlations with oral SCC.

Method

A search was made on the PUBMED database to select the main papers in the literature in English related to the subject, published between January 1991 and December 2011.

Conclusion

Myofibroblasts are an important component of the stroma of oral SCCs, although they are not present in all tumors. Abundant presence of myofibroblasts may be associated with local disease recurrence and decreased patient survival. However, given the relatively limited number of studies on the subject, further research is needed to clarify the molecular mechanisms by which myofibroblasts influence the biological behavior of oral SCC.

Development of a 4-nitroquinoline-1-oxide model of lymph node metastasis in oral squamous cell carcinoma

OBJECTIVES

Lymph node metastasis is one of the most important prognostic factors in oral squamous cell carcinoma. However, regional lymph node metastasis from oral cancer has barely been investigated in 4-nitroquinoline-1-oxide (4NQO) models. In this study, we developed a 4NQO-treated mouse model of oral squamous cell carcinoma that displayed lymph node metastasis and examined the occurrence and timing of the lymph node metastasis.

MATERIALS AND METHODS

BALB/c mice were treated with 200 μg/ml 4NQO in drinking water for 20 weeks and then followed for 4 weeks. Four mice were sacrificed bi-weekly, and oral lesion and regional lymph node metastasis were assessed during the week 25-32 and week 33-40 observation periods.

RESULTS

Tumor formation and local lymph enlargement were observed from 25 weeks onwards. The presence of metastatic tumor cells in the enlarged lymph nodes was confirmed via the detection of tumor infiltration by HE staining and cytokeratin positivity by immunostaining at both 28 and 36 weeks. The incidence rates of oral squamous cell carcinoma and local lymph node metastasis were 68.8% and 12.5% in the week 25-32 observation period, and 100% and 100% in the week 33-40 observation period, respectively.

CONCLUSIONS

A lymph node metastasis model involving mice being subjected to high-dose 4NQO treatment for a long period and then followed for a prolonged period was established. This model might provide a platform for studying the mechanism of lymphatic metastasis in oral carcinoma, leading to the development of new therapies for advanced oral carcinoma.

Stromal myofibroblasts in oral leukoplakia and oral squamous cell carcinoma

Objectives: Oral leukoplakia (OL) is the main potentially malignant disorder and oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral mucosa. Stromal myofibroblasts play an important role in tumor invasion and metastasis, due to its ability to modify the extracellular matrix. This study aimed to evaluate the presence of stromal myofibroblasts in OL and OSCC. Differences in the presence of myofibroblasts among OL with distinct grades of epithelial dysplasia as well as between histologically high- and low-invasive OSCC were also assessed. Study Design: A total of 30 OL and 41 OSCC from archival formalin-fixed, paraffin-embedded specimens were evaluated. 10 samples of normal oral mucosa were used as a control. Myofibroblasts were identified by immunohistochemical detection of alpha smooth muscle actin and its presence was classified as negative, scanty or abundant. Differences in the presence of myofibroblasts among OL with distinct grades of epithelial dysplasia as well as between high- and low-invasive OSCC were analyzed using the Mann-Whitney test. Results: Myofibroblasts were not detected in normal oral mucosa and OL, whatever its histological grade. In OSCC, the presence of stromal myofibroblasts was classified as negative in 11 (26.8%), scanty in 15 (36.6%), and abundant in 15 samples (36.6%). The presence of stromal myofibroblasts was statistically higher in high-invasive OSCC than in low-invasive OSCC (p<0.05). Conclusions: Stromal myofibroblasts were not detected in OL, indicating that these cells are not important during oral carcinogenesis. Nevertheless, stromal myofibroblasts were heterogeneously detected in OSCC and its presence was higher in tumors with a more diffuse histological pattern of invasion. These findings suggest that myofibroblasts are associated with the creation of a permissive environment for tumor invasion in OSCC.

Key words:Leukoplakia, oral squamous cell carcinoma, myofibroblast.

Warburg meets autophagy: cancer-associated fibroblasts accelerate tumor growth and metastasis via oxidative stress, mitophagy, and aerobic glycolysis

SIGNIFICANCE

Here, we review certain recent advances in oxidative stress and tumor metabolism, which are related to understanding the contributions of the microenvironment in promoting tumor growth and metastasis. In the early 1920s, Otto Warburg, a Nobel Laureate, formulated a hypothesis to explain the "fundamental basis" of cancer, based on his observations that tumors displayed a metabolic shift toward glycolysis. In 1963, Christian de Duve, another Nobel Laureate, first coined the phrase auto-phagy, derived from the Greek words "auto" and "phagy," meaning "self" and "eating."

RECENT ADVANCES

Now, we see that these two ideas (autophagy and aerobic glycolysis) physically converge in the tumor stroma. First, cancer cells secrete hydrogen peroxide. Then, as a consequence, oxidative stress in cancer-associated fibroblasts drives autophagy, mitophagy, and aerobic glycolysis.

CRITICAL ISSUES

This "parasitic" metabolic coupling converts the stroma into a "factory" for the local production of recycled and high-energy nutrients (such as L-lactate)-to fuel oxidative mitochondrial metabolism in cancer cells. We believe that Warburg and de Duve would be pleased with this new two-compartment model for understanding tumor metabolism. It adds a novel stromal twist to two very well-established cancer paradigms: aerobic glycolysis and autophagy.

FUTURE DIRECTIONS

Undoubtedly, these new metabolic models will foster the development of novel biomarkers, and corresponding therapies, to achieve the goal of personalized cancer medicine. Given the central role that oxidative stress plays in this process, new powerful antioxidants should be developed in the fight against cancer.

Immunohistochemical features of 3,3',4,4'-tetrachloroazobenzene-induced rat gingival lesions

Gingival lesions of squamous hyperplasia, cystic keratinizing hyperplasia (CKH), and squamous cell carcinoma (SCC) can be induced in rats treated by chronic gavage with 10-100 mg/kg 3,3',4,4'-tetrachloroazobenzene. We evaluated gingival squamous hyperplasia (GSH), CKH, and SCC for the immunohistochemical pattern of expression of carcinogenesis-associated markers. The 3 types of lesions and controls were stained with proliferation markers (proliferating cell nuclear antigen [PCNA] and cyclin-D1), tumor-suppressor markers (β-catenin and mammary serine protease inhibitor [maspin]) and stroma-related markers (α-smooth muscle actin [SMA] and osteonectin/SPARC). The lesions had common immunohistochemical characteristics that differed in their expression patterns among the various diagnoses. PCNA and cyclin-D1 expression was higher in GSH, CKH, and SCC than in controls. The normal membranous expression of β-catenin was lower in GSH, and almost absent in CKH and SCC. Maspin expression was similar in GSH and controls, whereas both CKH and SCC showed decreased expression. SMA and/or osteonectin/SPARC were seen in stromal cells in CKH and SCC. Collectively, there appears to be a progression from hyperplastic and cystic lesions toward malignancy based on the morphological changes, supported by the expression of carcinogenesis-associated proteins. The exact sequence of events leading to SCC remains to be defined in a time-dependent manner.

Cancer-associated fibroblasts, a parameter of the tumor microenvironment, overcomes carcinoma-associated parameters in the prognosis of patients with mobile tongue cancer

Mobile tongue squamous cell carcinoma (MTSCC) is known for its strong propensity for regional metastasis and poor patient survival despite aggressive treatment, thus calling for new and reliable markers for predicting prognosis and guiding therapeutic management. Towards this end, three classes of markers were investigated: cancer-associated fibroblasts (CAFs; α-SMA positivity) as a representative of the tumor microenvironment, maspin (mammary serine protease inhibitor) as a tumor marker likely to be modulated by factors within the tumor microenvironment, and DNA content and Ki-67 labeling index as inbuilt tumor markers in 128 cases of MTSCC using immunohistochemistry and image cytometry. Of these markers, only CAF density was independently and relatively strongly associated with elevated mortality from MTSCC. The hazard ratio in the CAF-rich type of tumor microenvironment was 4.85 (95% CI 1.41-16.6, versus the CAF-poor) when adjusted by proportional hazards modeling for the center where the patient was managed, gender, tumor stage, presence of neck metastasis and age at diagnosis. CAF density was unrelated to non-MTSSC mortality. Given the strong association between increased CAF density and higher mortality in MTSCC, routine assessment of CAF density for disease course prognosis and inclusion as an integral part of treatment protocols are recommended.

Cancer-associated fibroblasts and epithelial-mesenchymal transition in metastatic oral tongue squamous cell carcinoma

We examined cancer-associated fibroblasts (CAFs) and a panel of immunohistochemical markers of epithelial-mesenchymal transition (EMT) in 19 pair-matched oral tongue squamous cell carcinoma (SCC) and metastatic tumors to regional lymph nodes (RLNs). alpha-Smooth muscle actin (alpha-SMA) was studied to identify CAFs. EMT was studied with syndecan-1, Cadherin-11, fibroblast-specific protein (FSP)-1, secreted protein acidic and rich in cysteine (SPARC) and Twist. Triple immunostaining in RLNs was used to highlight the carcinoma cells (E-cadherin and Ki-67) and their relationship to the CAFs (alpha-SMA). We found that metastatic RLNs hosted CAFs similarly as in pair-matched primary tumors. Expression of EMT markers is common in both primary and metastatic tumors. We demonstrate that metastatic carcinoma cells (Ki-67 positive) downregulate E-cadherin expression at the periphery of cancer islands, where they are in direct contact with CAFs. The supporting connective tissue microenvironment also commonly expresses syndecan-1, Cadherin-11, FSP-1, and SPARC. In conclusion, CAFs are common to both primary and metastatic SCC. We hypothesize that CAFs not only promote tumor invasion but also facilitate metastases, either by cometastasizing and/or being recruited to lymph nodes. Evidence of EMT is common within primary tumors and metastatic SCC and may be further modulated by CAFs.

The effect of desalivation on the malignant transformation of the tongue epithelium and associated stromal myofibroblasts in a rat 4-nitroquinoline 1-oxide-induced carcinogenesis model

The aim of our study was to analyse desalivated rat tongue epithelium for histopathological changes, proliferating cell nuclear antigen (PCNA), and epithelium-associated stromal myofibroblasts [SMF; alpha-smooth muscle actin (alphaSMA)] following 0.001% 4-nitroquinoline 1-oxide (4NQO) administration in drinking water. Results were compared with those of identically treated but salivated specimens. 4NQO was administered for 7, 14, 22 and 28 weeks. Tongue length was divided into anterior, middle and posterior 'thirds'. The histopathological changes per 'third' were scored as normal epithelium, hyperplasia, dysplasia, carcinoma-in-situ, and superficial and invasive carcinoma. The PCNA and alphaSMA stains were assessed by a point-counting method. At all time points, the histopathological changes in the anterior and middle thirds were higher in the desalivated than in the salivated group (P < 0.05) but almost identical in the posterior third (P > 0.05). PCNA scores were significantly lower in the desalivated vs. the salivated group at almost all time points and tongue thirds (P < 0.05). SMF were usually scarce in both groups, but there was a significant surge in the posterior third at 28 weeks: the score in the desalivated group was only about one-half that of the salivated group (P < 0.05). The absence of saliva seems to promote malignant transformation of the tongue epithelium in the early stages. PCNA cannot be regarded as a marker of proliferation and probably contributes to this process by other mechanisms. Emergence of SMF seems to be highly dependent on growth factors from saliva in addition to factors from cancerous cells.

Stromal myofibroblasts accompany modifications in the epithelial phenotype of tongue dysplastic and malignant lesions

Stromal myofibroblasts (SMF) associated with various types of carcinomas are believed to emerge under the influence of the tumor cells. Recent studies have shown that SMF may originate from fibroblasts within the tumor stroma or even from carcinoma cells by the process of epithelial-mesenchymal transition. The aim of this study was to investigate the concomitant expression of epithelial membrane antigen and α-smooth muscle actin in cells at the tumor-connective tissue interface in human tongue carcinoma, as a possible reflection of epithelial-mesenchymal transition. Given its key role in this process, expression of transforming growth factor-β in the malignant cells was assessed as well. Immunostaining with α-smooth muscle actin was performed on cases of hyperplasia (n = 16), mild dysplasia (n = 12), moderate-to-severe dysplasia (n = 11) and carcinoma (n = 22). Transforming growth factor-β assessment and double immunostaining with epithelial membrane antigen and α-smooth muscle actin were performed only in cases of carcinoma. SMF were significantly associated with carcinomas, while their number in pre-malignant lesions (hyperplasia and dysplasia) was significantly lower (P < 0.001). Although SMF were found in all carcinomas, they were heterogeneous in their frequency and patterns of distribution. In addition, 95% of the carcinomas expressed transforming growth factor-β and 41% exhibited cells positive for both epithelial membrane antigen and α-smooth muscle actin. SMF were almost exclusively associated with established carcinomas and not with pre-malignant lesions. Cells that co-expressed epithelial membrane antigen and α-smooth muscle actin can be a manifestation of epithelial-mesenchymal transition and, as such, may serve as a source for SMF in these tumors. These findings appear to be linked to the frequent expression of transforming growth factor-β by the malignant cells.

The presence of Merkel cells and CD10- and CD34-positive stromal cells compared in benign and malignant oral tumors

BACKGROUND

To describe sequential changes in Merkel cells (MC), and CD10(+) and CD34(+) stromal cells (SC) during the transition from benign to malignant oral lesions and correlate with clinicopathologic parameters.

MATERIALS AND METHODS

Changes in cytokeratin 20-positive (CK20(+)) Merkel cells, CD10(+) and CD34(+) SC were immunohistochemically examined in specimens of 28 oral verrucous carcinomas (VC), 32 squamous cell carcinomas (SCC) and 36 benign squamous lesions (BSL). Immunoreactivity and localized inflammation were measured quantitatively and/or semiquantitatively, and between-group results were statistically compared.

RESULTS

The mean number of CD34(+) SC was significantly lower in VC (57.36) and SCC (33.81) than BSL (351.56, P < 0.001). However, the three tumor types had similar staining level and number of CD10(+) SC. We found a significant difference in the density of MC between BSL and VC (P < 0.001) or SCC (P < 0.001). The number of CK20(+) MC was significantly lower in highly inflamed specimens than mildly inflamed specimens (P = 0.001).

CONCLUSION

CD34(+) SC and to a lesser extent MC, but not CD10(+) SC, reveal statistically different density during the transition from benign to malignant oral lesions. The correlations between the CD34(+) SC expression and squamous lesions may be associated with epithelial dysplasia and/or tumor invasion.

Recent advances in Oral Oncology 2007: epidemiology, aetiopathogenesis, diagnosis and prognostication

This paper provides a synopsis of the main papers on epidemiology, diagnosis and prognosis of oral and oropharyngeal squamous cell carcinoma (OSCC) and head and neck SCC (HNSCC) published in 2007 in Oral Oncology - an international interdisciplinary journal which publishes high quality original research, clinical trials and review articles, and all other scientific articles relating to the aetiopathogenesis, epidemiology, prevention, clinical features, diagnosis, treatment and management of patients with neoplasms in the head and neck, and orofacial disease in patients with malignant disease.