Identification and characterization of autocrine-motility-factor-like activity in oral squamous-cell-carcinoma cells

Precise analysis of single small extracellular vesicles using flow cytometry

Methods that enable specific and sensitive quantification of small extracellular vesicles (sEVs) using flow cytometry are still under development. Aggregation or adsorption of antibodies causes sub-nano sized particles or non-specific binding and largely affects the results of flow cytometric analysis of single sEVs. Comparison of control IgG and target-specific IgG is inappropriate because they have different characters. Here, we evaluate four preparation methods for flow cytometry, including ultracentrifugation, density gradient centrifugation, size exclusion chromatography (SEC), and the TIM4-affinity method by using tetraspanin-deficient sEVs. The ultracentrifugation or density gradient centrifugation preparation method has large false-positive rates for tetraspanin staining. Conversely, preparation methods using SEC or the TIM4-affinity method show specific detection of single sEVs, which elucidate the roles of sEV biogenesis regulators in the generation of sEV subpopulations. The methods are also useful for the detection of rare disease-related markers, such as PD-L1. Flow cytometric analysis using SEC or the TIM4-affinity method could accelerate research into sEV biogenesis and the development of sEV-based diagnostics and therapies.

An oncolytic virus as a promising candidate for the treatment of radioresistant oral squamous cell carcinoma

We evaluated the usefulness of an oncolytic virus (Suratadenoturev; OBP-301) against radioresistant oral squamous cell carcinoma. We confirmed the expression of human telomerase reverse transcriptase and the coxsackievirus and adenovirus receptor in cell lines. Also, we examined the potential presence in a patient who has received existing therapy that is amenable to treatment with OBP-301. We evaluated: (1) the antitumor effects of OBP-301 alone and in combination with radiotherapy on radioresistant cell lines, (2) the molecular mechanism underlying the radiosensitizing effect and cell death increased by the combination therapy, and (3) the antitumor effect of the combination therapy in vivo using xenograft models (a radioresistant cell line-derived xenograft in mouse and a patient-derived xenograft). Human telomerase reverse transcriptase and the coxsackievirus and adenovirus receptor were expressed in all cell lines. OBP-301 decreased the proliferative activity of these cell lines in a concentration-dependent manner, and significantly enhanced the antitumor effect of irradiation. Phosphorylated STAT3 and its downstream molecules, which correlated with apoptosis and autophagy, showed significant changes in expression after treatment with OBP-301. The combination therapy exerted a significant antitumor effect versus radiotherapy alone in both xenograft models. Combination of OBP-301 with radiotherapy exerts a synergistic effect and may represent a promising treatment for radioresistant oral squamous cell carcinoma.

Cell culture models of oral mucosal barriers: A review with a focus on applications, culture conditions and barrier properties

Understanding the function of oral mucosal epithelial barriers is essential for a plethora of research fields such as tumor biology, inflammation and infection diseases, microbiomics, pharmacology, drug delivery, dental and biomarker research. The barrier properties are comprised by a physical, a transport and a metabolic barrier, and all these barrier components play pivotal roles in the communication between saliva and blood. The sum of all epithelia of the oral cavity and salivary glands is defined as the blood-saliva barrier. The functionality of the barrier is regulated by its microenvironment and often altered during diseases. A huge array of cell culture models have been developed to mimic specific parts of the blood-saliva barrier, but no ultimate standard in vitro models have been established. This review provides a comprehensive overview about developed in vitro models of oral mucosal barriers, their applications, various cultivation protocols and corresponding barrier properties.

Regulation of programmed-death ligand in the human head and neck squamous cell carcinoma microenvironment is mediated through matrix metalloproteinase-mediated proteolytic cleavage

Recurrent and/or metastatic head and neck squamous cell carcinoma (R/M HNSCC) is a devastating malignancy with a poor prognosis. According to recent clinical studies, tumour growth can be effectively reduced and survival can be improved by blocking the programmed death receptor-1 (PD-1)/programmed death-ligand 1 (PD-L1) pathway. PD-L1 expression has been proposed as a potential causative mechanism, as HNSCC is highly immunosuppressive. However, anti-PD-1 treatment is beneficial only for certain patients. Therefore, the mechanisms controlling PD-L1 expression warrant further investigation in order to provide a better understanding of the predicting efficacy of and optimising anti-PD-1 therapy, alone or in combination. In this study, PD-L1 protein extracted from the cell membrane was found to be downregulated in OSC-20 cells compared with OSC-19 cells, despite a higher PD-L1 expression in the total cell lysate of the OSC-20 compared with the OSC-19 cells. Several matrix metalloproteinases (MMPs) were found to be upregulated in HNSCC; in particular, MMP-7 and -13 were upregulated in the OSC-20 compared with the OSC-19 cells. Purified PD-L1 was degraded by recombinant MMP-13 and -7. The expression of PD-L1 was significantly restored by a specific inhibitor of MMP-13 (CL82198), which suggested the involvement of MMP-13 in the shedding/cleavage of PD-L1 in the OSC-20 cells. Among the anticancer drugs conventionally used in the treatment of patients with HNSCC, paclitaxel increased MMP-13 expression in R/M HNSCC cells (HOC313 cells) co-cultured without/with dendritic cells (DCs). These results suggest that the shedding/cleavage of PD-L1 by MMP-13 is one of the mechanisms behind the protective effect against invasion and metastasis. Thus, MMP-13 has potential value as a marker predictive of the decreased efficacy of anti-PD-1 therapy. In addition, paclitaxel is a particularly promising candidate for combination therapy in R/M HNSCC with anti-PD-1 therapy.

Eribulin sensitizes oral squamous cell carcinoma cells to cetuximab via induction of mesenchymal-to-epithelial transition

Inhibition of epidermal growth factor receptor (EGFR) signalling has emerged as a new treatment strategy for oral squamous cell carcinoma (OSCC). Previously, we found that loss of EGFR expression in OSCC was associated with epithelial-mesenchymal transition (EMT), and may have functional implications with regard to resistance to cetuximab, a monoclonal anti-EGFR antibody. Eribulin (a microtubule inhibitor) reportedly renders breast cancer less aggressive, and less likely to metastasise, by triggering mesenchymal-to-epithelial (MET) transition. In the present study we evaluated whether eribulin-induced MET was associated with re-sensitization of resistant OSCC cell lines to cetuximab. In vitro antiproliferative activities were determined in three human OSCC lines (OSC-20, OSC-19 and HOC313) treated with eribulin. These three human OSCC represented different EMT/MET states. Interestingly, HOC313 cells (mesenchymal phenotype) were highly sensitive to eribulin in comparison with other cell lines, and significantly enhanced the anti-proliferative effect of cetuximab in response to the drug. Eribulin also underwent a MET-associated gene switch that resulted in morphological changes and high EGFR expression in HOC313 cells, and abrogated a TGF-β-induced EMT gene expression signature. Eribulin-dependent sensitization of OSCC to cetuximab is likely due to induction of MET. Combination therapies based on eribulin and cetuximab have potential as a novel treatment regimen in OSCC.

Loss of epidermal growth factor receptor expression in oral squamous cell carcinoma is associated with invasiveness and epithelial-mesenchymal transition

Inhibition of epidermal growth factor receptor (EGFR) signaling has emerged as a novel therapeutic strategy for the treatment of oral squamous cell carcinoma (OSCC). The EGFR-directed inhibitor cetuximab is currently the only approved targeted therapy for the treatment of OSCC. EGFR status may affect the patient response to cetuximab treatment. In the present study, via analysis of the immunomarker for EGFR, it was revealed that 58.3% of the total cases investigated stained positively for EGFR expression, and furthermore, that invasiveness was inversely correlated with EGFR expression. Expression levels of EGFR were quantified, and the correlation between EGFR expression and cetuximab sensitivity was investigated using three varying grades of invasive human OSCC line. EGFR expression in high-grade invasive cells was significantly downregulated compared with that of low-grade invasive cells. There was no significant antiproliferative effect in the high-grade invasive cells treated with various concentrations of cetuximab. The EMT-associated genes, N-cadherin, vimentin and Snail, were upregulated in the high-grade invasive cells. The low-grade invasive cells exhibited characteristics of typical epithelial cells, including the expression of E-cadherin and absence of the expression of N-cadherin, vimentin and Snail. Transforming growth factor-β induced low-grade invasive cells to undergo an epithelial-mesenchymal transition (EMT)-associated gene switch, which resulted in low levels of EGFR expression. The results of the present study suggested that loss of EGFR expression in OSCC was associated with EMT, and may have functional implications with regard to tumor invasiveness and the resistance to cetuximab treatment.

Prognostic value of vascular endothelial growth factors A and C in oral squamous cell carcinoma

BACKGROUND

Vascular endothelial growth factor (VEGF) family members play a major role in angiogenesis and vascularization. VEGF-A promotes tumor angiogenesis by stimulating the growth of tumor vascular endothelial cells. In addition, VEGF-C has been identified as a potent inducer of lymphangiogenesis in tumor and lymph node metastasis. Previous studies have investigated the association between clinicopathological factors and the expression of VEGF-A and VEGF-C in oral squamous cell carcinoma cancer (OSCC), but the results are contradictory. In this study, we investigated the relationship between VEGF-A and VEGF-C expression and OSCC clinicopathological factors and prognosis.

METHODS

Expression of VEGF-A and VEGF-C was evaluated in surgical specimens from 61 patients with OSCC and three human oral cancer cell lines (OSC-19, OSC-20 and HOC313) by immunohistochemical staining and enzyme-linked immunosorbent assay, respectively. We also determined the relationship between the 5-year survival rate and clinicopathological factors, such as TNM classification (Union for International Cancer Control, UICC), lymph node metastasis, recurrence, histological differentiation, location, and mode of invasion.

RESULTS

VEGF-A expression correlated significantly with lymph node metastasis. VEGF-C expression was associated with lymph node metastasis, recurrence, and a poorer 5-year survival rate. A multivariate analysis demonstrated that VEGF-C is an independent prognostic factor for patients with OSCC. VEGF-C expression was significantly up-regulated in HOC313 cells compared to OSC-19 and OSC-20 cells.

CONCLUSIONS

These results indicate that VEGF-C may be a predictive factor for OSCC outcome, lymph node metastasis, and recurrence. Moreover, VEGF-C may be an important factor in the development of new therapies for OSCC patients.

Downregulation of Fanconi anemia genes in sporadic head and neck squamous cell carcinoma

BACKGROUND/AIMS

Much of our understanding of human cancer has come from studies of the hereditary cancer predisposition syndromes. Fanconi anemia (FA) is an autosomal recessive disorder characterized by cellular hypersensitivity to DNA crosslinking agents, progressive bone marrow failure, and cancer predisposition to solid malignancies, especially head and neck squamous cell carcinoma (HNSCC). Since FA pathway-deficient cells are hypersensitive to DNA crosslinking chemotherapy agents, the presence of somatic FA gene inactivation in sporadic cancers may be of clinical interest. This study sought to determine the frequency of FA gene downregulation in sporadic HNSCC.

METHODS

The expression of the FA genes FANCA, FANCB, FANCC, FANCD2, FANCE, FANCF, FANCG, FANCJ, FANCL and FANCM in 11 HNSCC cell lines and 49 tongue carcinoma samples was studied with quantitative real-time polymerase chain reaction.

RESULTS

Downregulation of at least one FA gene was observed in 3 of 11 HNSCC cell lines and 66% of tongue carcinoma samples. FANCB, FANCF, FANCJ and FANCM were most commonly affected by downregulation, whereas downregulation of FANCA, FANCE and FANCD2 was rare.

CONCLUSION

Our data suggest that downregulation of FA genes is common in sporadic HNSCC. The clinical implications of this finding merit further study. .

CHARACTERIZATION OF HUMAN MELANOMA CELL LINES ACCORDING TO THEIR MIGRATORY PROPERTIES IN VITRO

The migratory responses of four human melanoma cell lines (A-2058, DEMEL, HTB-63, and HTB-72), using chemotaxis (CTX) and haptotaxis (HPTX) assays, were studied. The attractants were three extracellular matrix components (EMCs), fibronectin, laminin, and collagen type IV. The conditioned media (CM) of each cell line were used to study autocrine and paracrine responses. A screening and sensitive CTX assay was performed, using pertussis toxin (PTX)- treated A-2058 as responder cells; the other melanoma cells and normal cells were used as secretory cells. Autotaxin (ATX), a purified autocrine motility factor, was also used as a chemoattractant. Reverse transcriptase-polymerase chain reaction was used to detect the expression of ATX by all cell lines. The secretion of ATX was determined by Western blot. The invasive capacity of the cell lines was evaluated using Matrigel and ATX as attractant. Chemotaxis responses to EMCs varied. Except for the A-2058 cells, HPTX migration was low. Autocrine and paracrine responses also varied. The migration of PTX-treated A-2058 cells to ATX and to their own CM was abolished. All the melanoma cells expressed ATX, and except for the HTB-72 and normal cells, all secreted ATX. Matrigel was invaded by all the melanoma cell lines except the HTB-72 and normal cells. The migratory properties of human melanoma cells in vitro suggest that they could correlate to their metastatic potential in vivo.

Tumor cell motility and metastasis : Autocrine motility factor as an example of ecto/exoenzyme cytokines

Cellular locomotion plays a critical role in such normal processes as embryonic development, tissue segregation, as well as the infiltration of fibroblasts and vascular cells during wound repair and the inflammatory responses of the adult immune system. During tumor invasion and metastasis the processes of cell migration achieve dire significance. Disruption of normal homeostatic mechanisms to benefit the survival of the individual tumor cell is a common theme discovered during the characterization of factors once thought to be tumor-specific. One such molecule, tumor cell autocrine motility factor, was so described and has only recently been identified as a normal protein involved in intracellular glycolysis as well as implicated as an extracellular effector of normal cell functions including survival of certain populations of neurons. This molecule represents a member of the newly emerging family of intracellular enzymes whose disparate functions as extracellular mediators of cellular responses defines a new class of ecto/exoenzymes which play a role in normal cellular processes and are inappropriately utilized by tumor cells to elicit new survival strategies.

Identification and characterization of motility stimulating factor secreted from pancreatic cancer cells: role in tumor invasion and metastasis

Cell motility is an important factor in the process of invasion and metastasis of tumor. In this study, the relationship between cell motility and experimental metastatic potential was examined using two human pancreatic cancer cell lines, SW1990 and PANC-1. Serum-free conditioned medium from the highly metastatic cell line SW1990 was found to contain a factor that stimulated the migration of and induced a fibroblast-like morphological change in the weakly metastatic cell line PANC-1. Preincubation of PANC-1 cells with SW1990 conditioned medium (SW-C.M.) induced liver metastasis following splenic injection of PANC-1 cells in nude mice, although no liver metastasis was observed without pretreatment of SW-C.M. This factor, temporarily termed PDMF (pancreatic cancer-derived motility factor) is a heparin non-binding protein having a molecular weight of 40 kDa calculated by gel-filtration HPLC which acts not only chemotactically but also chemokinetically, and also acts mainly in a paracrine fashion. However, this factor had no effect on the proliferation of PANC-1 cells; it therefore appears to be a so-called motility factor. Only TGF-beta1 and IL-6 were recognized in the SW-C.M. among cytokines thought to stimulate cell motility. These cytokines stimulated the motility of PANC-1 cells, but differed from PDMF in the neutralizing test with antibody against these cytokines. Results of characterization and preliminary purification suggest that this factor may be a novel motility factor. The above findings suggest that this motility factor may play an important role in the invasion and metastasis of pancreatic cancer, and complete purification of it will be useful in elucidating the mechanism of progression of cancer and designing a strategy for inhibition of invasion and metastasis of pancreatic cancer.

Regulation of the invasion suppressor function of the cadherin/catenin complex

Invasion is the cause of cancer malignancy. Invasion results from the cross-talk between cancer cells and host cells, building molecular invasion-promoter and invasion-suppressor complexes. The E-cadherin/catenin invasion-suppressor complex is regulated multifactorially, at multiple levels and sometimes in a reversible way. Mutations in the E-cadherin gene combined with loss of the wild type allele, causing irreversible downregulation, has been demonstrated only in a minority of human cancers. Posttranslational and reversible downregulation has been ascribed to tyrosine phosphorylation of beta-catenin. Phosphorylation is also implicated in transmembrane receptor signal transduction through the E-cadherin/catenin complex. E-cadherin interacts with E-cadherin on another cell through a dimeric adhesion zipper, involving the histidine-alanine-valine (HAV) sequence of the first extracellular domains. This is the major extracellular like of the E-cadherin/catenin complex, though not the only one. Intracellularly, the list of proteins that bind to or signal through the complex or through one or more of its elements is steadily growing. Extrinsic factors may influence the complex. At least in vitro, insulin-like growth factor-I, retinoic acid, tangeretin and tamoxifen were shown to upregulate the functions of the E-cadherin/catenin complex including inhibition of invasion.

Cell, tissue and organ culture as in vitro models to study the biology of squamous cell carcinomas of the head and neck

In vitro models are currently being used to study head and neck squamous cell carcinoma (HNSCC). Several hundred HNSCC cell lines have been established by various investigators and used to study a broad spectrum of questions related to head and neck cancer. The head and neck model with respect to multistage carcinogenesis is now complete. Several techniques exist for the culture of normal epithelial cells from the upper aerodigestive tract (UADT). The biology of these UADT cells (oral cavity, oropharynx, hypopharynx and larynx) is being studied. Successful culture of premalignant lesions (dysplastic mucosa, leukoplakia, erythroplakia) has resulted in establishment of a limited number of premalignant cell lines and cell cultures. HPV infection of normal oral epithelial cells for immortalization (approximately premalignant cells) coupled with transformation with carcinogens (malignant cells) has established an experimental model for progression. Two in vivo models for oral carcinogenesis, the 7,12 dimethylbenz(a)anthracene-induced hamster cheek pouch model and the 4-nitroquinoline-N-oxide rat oral model, have been established in culture. Thus, multistage carcinogenesis models have been established from both human tissues and animal models and include cultures of normal, premalignant and malignant cells. Culture techniques for growing dissociated primary tumor cells for short term experimental analysis are being used. The culture of normal or tumor tissue as organ/explant cultures allows for the maintenance of normal cell-cell and cell-matrix interaction, but limits experimentation since these cultures cannot be propagated. Several three dimensional model systems are being used to obtain this histological complexity but allow for experimentation. The ability to culture normal, premalignant and malignant cells coupled with the use of a variety of culture techniques, should allow for the continued growth and experimentation in head and neck cancer research.

Loss of cell-contact regulation and altered responses to autocrine motility factor correlate with increased malignancy in prostate cancer cells

Tumor cell migration and proliferation in new organ environments are critical steps in cancer progression and can be modulated by tumor- and host-secreted molecules. Autocrine motility factor (AMF) is a tumor-secreted cytokine which regulates growth and motility by a receptor-mediated pathway. The AMF receptor, a 78-kDa cell surface glycoprotein (gp78), is regulated by cell contact in normal fibroblastic and bladder cells; however, this mechanism is disrupted during tumor progression. A prostatic carcinoma cell line which is low- to non-metastatic in nude mice (PC-3) and a derived metastatic variant (PC-3M) were examined to determine if gp78 cell density regulation is involved in prostate cancer progression. Both cell lines expressed gp78 and, although the basal migration of the parental PC-3 cells was higher than that of the metastatic variant, only the PC-3M cells were capable of responding to tumor-derived AMF with increased motility. Furthermore, these cells exhibited differential patterns of wound closure in an experimental system whereby the low-metastatic PC-3 cells migrated primarily along the wound edge while individual high-metastatic PC-3M cells entered the cell-free wound area directly. Cell surface gp78 distribution distinguished the cell populations with a markedly concentrated display of gp78 in polarized capped regions on the surface of the metastatic cells. Cell-cell contact down-regulated gp78 expression in the parental, but not the metastatic, cells, and mitogenic responses to exogenous AMF differed between these cell lines as well. In this model, metastasis appears to be associated with aberrant regulation of gp78 expression and distribution, coupled with enhanced exploitation of AMF's locomotory and proliferative effects.

Short insertions in the partner strands greatly enhance the discriminating power of DNA heteroduplex analysis: resolution of HLA-DQB1 polymorphisms

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Enhancement of retrovirus-mediated gene transduction efficiency by transient overexpression of the amphotropic receptor, GLVR-2

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