RhoA/ROCKs signaling is increased by treatment with TKI-258 and leads to increased apoptosis in SCC-4 oral squamous cell carcinoma cell line

BACKGROUND

This study evaluated the effect of treatment with TKI-258 on apoptosis, involving Rho GTPases and their effectors in SCC-4 cells of oral squamous cell carcinoma.

METHODS

Markers of cell death and apoptosis were analyzed in control and TKI-258-treated SCC-4 cells by flow cytometry. The involvement of Rho GTPases and effectors in the induction of apoptosis by TKI-258 was evaluated by quantification of cleaved PARP. Also, gene expression analysis of those proteins was performed.

RESULTS

The treatment with TKI-258 led to a significant increase in cell death (7-AAD) and apoptosis (annexin V and cleaved PARP). When Rho GTPases were stimulated with LPA and inhibited with toxin A Clostridium difficile, the percentage of apoptotic cells increased and decreased, respectively. A similar effect was found when the treatment was with TKI-258 combined with LPA and toxin A. Treatment with TKI-258 significantly increased RhoA gene expression, while RhoB, RhoC, Rac1, and Cdc42 decreased significantly. ROCKs inhibitors (Y-27632 and HA-1077) reduced apoptosis compared with control. TKI-258 combined with Y-27632 or HA-1077 led to an increase in apoptosis compared with inhibitors only. Treatment with TKI-258 led to an increase in ROCK1 and ROCK2 gene expression, and a decrease in PAK1 and PAK2 gene expression.

CONCLUSIONS

TKI-258 stimulates apoptosis in SCC-4 cells of oral squamous cell carcinoma. Possibly, RhoA GTPase and their effectors ROCKs participate in the signaling pathway inhibited by TKI-258.

CLINICAL RELEVANCE

Therapies with multi-target inhibitors, such as TKI-258, may be promising alternatives for the clinical treatment of oral squamous cell carcinoma.

Cetuximab has an inhibitory effect on cell motility in SCC-4 oral squamous cell carcinoma cell line

Cetuximab is a chimeric monoclonal antibody that acts as a competitive antagonist, by binding to EGFR. This cell signalling pathways regulates tumor progression. The oral squamous cell carcinoma undergoes to regional spreading and distant metastasis. This study aimed to evaluate the effect of treatment with Cetuximab on cell migration and invasion in OSCC cells, by using the SCC-4 cell line. Cell migration and cell invasion assay were performed and actin cytoskeleton of control and treated with Cetuximab cells were evaluated. Differences were considered significant when p<0.05.Cetuximab inhibited the migration of SCC-4 cells at three concentrations: 1 µg/mL, 50 µg/mL and 100 µg/mL (p<0.0001) in a dose-dependent manner. The number of SCC-4 treated cells with 1 μg/mL that migrated through the membrane was statistically different from 50 μg/mL (p<0.001) and 100 μg/mL (p<0.0001), and between 50 μg/mL and 100 μg/mL (p<0.01). Cetuximab 50 μg/mL inhibited cell invasion through the MatrigelTM compared with SCC-4 control cells (p<0.01). Cetuximab 50 μg/mL affected the organization of the actin cytoskeleton. Cetuximab has an inhibitory effect on actin cytoskeleton organization, cell migration and invasion, suggesting that Cetuximab treatment can be important to avoid oral squamous cell carcinoma metastasis.

Tyrosine kinase inhibitor TKI-258 inhibits cell motility in oral squamous cell carcinoma in vitro

BACKGROUND

Oral squamous cell carcinoma is extremely invasive, and this behavior is regulated by binding of extracellular molecules to the cell membrane receptors. The TKI-258 inhibits phosphorylation of FGFRs VEGFRs and PDGFRs. Our aim was to analyze the effect of TKI-258 treatment in cell movement using SCC-4 cell line from human oral squamous cell carcinoma.

METHODS

F-actin was stained with rhodamine phalloidin, and confocal analysis was performed. The migration and invasion (membrane covered with Matrigel^™ ) three-dimensional assays were performed, and control and cells treated with TKI-258 that migrated through the membrane were counted after 24 h.

RESULTS

Control cells presented abundant cytoplasm with F-actin wide distributed and evident cell cortex; however, treated (1, 5 and 10 μM TKI-258) cells showed round morphology, scanty cytoplasm, F-actin disorganized and preserved cell cortex. TKI-258 (1, 5, and 10 μM) treatment inhibits migrating cells (ANOVA, F = 97.749, d.f. = 3, 10; P < 0.0001), and it was concentration dependent. Invading cell treated with 5 μM TKI-258 was significantly lower (t = 6.708, d.f. = 5, P < 0.001).

CONCLUSIONS

These results suggest that the tyrosine kinase inhibitor TKI-258 has an inhibitory effect on cell motility, affecting F-actin, cell migration, and cell invasion, and probably, these processes are regulated by signaling pathways FGFRs and/or PDGFRs and/or VEGFRs.

Immunohistochemical study of RhoC GTPase in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a disease with high mortality and morbidity. Metastasis is a significant prognostic factor of the OSCC patients. The Rho GTPases are signaling proteins that controls important cellular processes in various complex mechanisms involved in carcinogenesis. This study aimed to evaluate the expression pattern of RhoC in OSCC protein by immunohistochemistry in situ. Immunohistochemical reactions were performed for RhoC by the method of avitina-biotin-peroxidase activity in samples OSCC: well differentiated (BD, n=6), moderately differentiated (MD, n=24) and poorly differentiated (PD, n=13). The morphometry was taken by QuickScore (percentage and intensity of staining) and only intensity staining. There was no statistical difference (p>0.05) through none of the modes of morphometric analysis between BD, MD and PD. And the RhoC staining was not associated with the histopathologic grading (χ2 = 4.65, p>0.05). However, the morphological evaluation of immunostained for RhoC in cases BD, MD, PD OSCC, regardless of histopathologic grading. These results suggest that there is no correlation between the RhoC immunoexpression and histopathological grading of OSCC.

Depressive behavior induced by social isolation of predisposed female rats

Depression is a mood disorder that is more prevalent in women and has been closely associated with chronic stress. Many models of depression have been suggested that consider different forms of stress. In fact, stress is present in the life of every human being, but only a few develop depression. Accordingly, it seems wrong to consider all stressed animals to be depressed, emphasizing the importance of predisposition for this mood disorder. Based on this finding, we evaluated a predisposition to depressive behavior of female rats on the forced swim test (FST), and the more immobile the animal was during the FST, the more predisposed to depression it was considered to be. Then, animals were subjected to the stress of social isolation for 21 days and were re-evaluated by the FST. The Predisposed/Isolated rats presented higher immobility times. Once all the rats had prior experience in the FST, we calculated an Index of Increase by Isolation, confirming the previous results. Based on this result, we considered the Predisposed/Isolated group as presenting depressive behavior ('Depressed') and the Nonpredisposed/Nonisolated group as the control group ('Nondepressed'). The animals were distributed into 4 new groups: Nondepressed/Vehicle, Nondepressed/Amitriptyline, Depressed/Vehicle, Depressed/Amitriptyline. After 21 days of treatment, only the Depressed/Vehicle group differed from the other 3 groups, demonstrating the efficacy of amitriptyline in treating the depressive behavior of the Depressed animals, validating the model. This study shows that conducting an FST prior to any manipulation can predict predisposition to depressive behavior in female rats and that the social isolation of predisposed animals for 21 days is effective in inducing depressive behavior. This behavior can be considered real depressive behavior because it takes into account predisposition, chronic mild stress, and the prevalent gender.

Immunolocalization of RhoA and RhoB GTPases in pleomorphic adenoma of the parotid

The pleomorphic adenoma of the parotid (PA) is characterized by the high tissues diversity. Rho GTPases participate in signal transduction pathways that regulate several biological processes, including cell differentiation. A quantitative analysis of RhoA and RhoB GTPases immunoexpression was performed in healthy parotids and in 23 PA cases, predominantly epithelial (PE) or mesenchymal (PM), followed by Student's t test. In PE cases, RhoA immunoexpression was higher in sheets and trabeculae (p < 0.05), whereas RhoB only in sheets (p < 0.05). In normal parotids, RhoA and RhoB were not detected in acinar cells. Ducts have expressed RhoA and RhoB in normal parotids and PA. RhoB was detected in myxoid and chondromyxoid cells. Normal parotids do not express RhoA and RhoB proteins in acinar cells, indicating a lack of function in secretory cells. Despite RhoA and RhoB GTPases are different in their biological roles, no significant difference in immunoexpression of the RhoA and RhoB GTPases in epithelial and mesenchymal structures of PA.

A study on biocompatibility of three endodontic sealers: intensity and duration of tissue irritation

INTRODUCTION

Several studies have evaluated the inflammatory reaction triggered by Epiphany (EPH), a contemporary endodontic sealer. However, they used conventional parameters, which need additional analysis to better understand the reactions induced by this sealer compared to other traditional sealers.

METHODS AND MATERIALS

The intensity and time span of tissue irritations for three endodontic sealers were assessed by inflammatory reactions, fibrous capsule measurement and mast cell counts. Tubes containing freshly mixed EPH, AH plus (AHP) and Endofill (ENF) were subcutaneously implanted into the backs of 28 Wistar rats. The side wall of the tube was used as the control. At 14, 21, 42 and 60 days, the connective tissue surrounding the implants (n=7) was stained for histopathological analysis. The Friedman test was applied to compare the results. The level of significance was set at 0.05.

RESULTS

At days 14 and 21, a significant difference among the groups was observed, with the ENF showing the worst tissue response (P<0.001). ENF remained the most aggressive sealer at 42 and 60 days, compared with EPH (P<0.05). No differences were found for the fibrous capsule thicknesses among the groups in each period. The number of mast cells per field did not show difference among the sealers at 21 and 60 days.

CONCLUSIONS

EPH and AHP elicited similar patterns of irritation, as demonstrated by the inflammatory scores and fibrous capsule thicknesses. ENF caused the highest degree of tissue damage. The increase in mast cell counts observed during the early and late periods shows the possibility of late hypersensitivity to the test materials.

GTPases Rho distribution in intraepithelial and invasive neoplasias of the uterine cervix

PURPOSE OF INVESTIGATION

To evaluate the distribution of GTPases RhoA, RhoB, and Cdc42 in cervical intraepithelial neoplasias (CIN) and invasive neoplasias of the uterine cervix.

MATERIALS AND METHODS

samples of neoplastic lesions of the uterine cervix of 44 patients were classified in: CIN I (n = 10), CIN II (n = 10), CIN III (n = 09), and invasive carcinoma (n = 15). Antibodies anti-RhoA, anti-RhoB, and anti-Cdc42 were used and staining was classified as: negative, mild, moderate, and intense positive.

RESULTS

When compared with dysplastic cells, superficial cells showed: higher expression of RhoB in CIN I (p = 0.0018), and lower expression of Cdc42 in CIN I (p = 0.0225). The authors observed higher expression of RhoA (p = 0.0002) and RhoB (p = 0.0046) in CIN dysplastic cells when compared with invasive carcinoma cells.

CONCLUSIONS

GTPases Rho may be involved with the regulation of biological processes, important to the progression of cervical neoplasias. Probably, RhoA is important for maintenance of cell differentiation and RhoB protects cells from malignant cervical neoplasia.

Immunohistochemical expression of Rho GTPases in ameloblastomas

Rho GTPases are proteins that regulate cell cycle, shape, polarization, invasion, migration, and apoptosis, which are important characteristics of normal and neoplastic cells. Rho GTPases expression has been reported in normal tooth germ and several pathologies; however, it has not been evaluated in ameloblastomas. The aim of this study was to analyze the expression and distribution of RhoA, RhoB, Rac1, and Cdc42 Rho GTPases in solid and unicystic ameloblastomas. Three-micrometer sections from paraffin-embedded specimens were evaluated by using an avidin-biotin immunohistochemical method with antibodies against the proteins mentioned above. RhoA and RhoB staining was observed in a high number of cells (P < 0.05) and greater intensity in non-polarized ones. Rac1 was not observed, and Cdc42 did not show any statistical differences between the number of non-polarized and basal positive cells (P > 0.05). Upon comparing the studied ameloblastomas, a higher number of positive cells in the unicystic variant was observed than that in the solid one (P < 0,05). The results obtained suggest that these GTPases could play a role in the ameloblastoma neoplastic epithelial cell phenotype determination (polarized or non-polarized), as well as in variant (solid or unicystic) and subtype (follicular or plexiform) determination. Furthermore, they could participate in solid ameloblastoma invasion mechanisms.

A mandibular propulsive appliance modulates collagen-binding integrins distribution in the young rat condylar cartilage

We have previously shown that a mandibular propulsive appliance (MPA) stimulates cell proliferation and the synthesis of growth factors in the rat condylar cartilage. The aim of this study was to evaluate the effects of a MPA in the distribution of the integrin subunits alpha1 and alpha2 in this cartilage. Twenty eight days-old male Wistar rats were divided into treated (T) and age-matched control groups (C). Treated rats wore the appliance during 3, 5, 7, 9, 11, 15, 20, 30 and 35 days. The condyles were fixed, decalcified and paraffin-embedded. The distribution of alpha1 and alpha2 was studied by immunohistochemistry. Alpha1 distribution was uniform along the cartilage, increasing in 48 days-old rats (C20). Treated animals anticipated this increase to the age of 36 days (T9). The number of alpha2-positive cells was increased in C9 in the anterior condylar region, in C9 and C20 in the middle region and showed no differences in the posterior region. The MPA apparently abolished all variations, leading to a single increase at T30 in all regions. These results suggest that integrins containing the alpha1 and alpha2 subunits are modulated by forces promoted by the MPA, participating of the biological response to this therapy.