Immunohistochemical analysis of inducible nitric oxide synthase (iNOS) and heat shock proteins (HSPs) in ameloblastomas

Assessment of nebivolol efficacy in experimental models of toxoplasmosis: insights into parasite burden reduction and neuronal protection

This study investigates the efficacy of nebivolol (NBV) in experimental models of toxoplasmosis, focusing on parasite burden reduction and neuronal protection. In the acute model of experimental toxoplasmosis, Swiss mice infected with RH strain tachyzoites received oral NBV chlorhydrate doses of 2 mg/kg/day and 4 mg/kg/day for 8 days. Treatment with NBV significantly reduced parasite burden compared to vehicle and standard drug (PYR) groups. In the chronic model of experimental toxoplasmosis, C57/BL6 mice infected with the ME49 strain received NBV chlorhydrate 41 days post-infection and were evaluated after 10 days of treatment. NBV chlorhydrate effectively reduced cyst number and area, as well as bradyzoite burden compared to controls. Histological analysis demonstrated that NBV chlorhydrate preserved neuronal count, with the 4 mg/kg/day dose yielding counts similar to non-infected mice. Statistical analysis confirmed significant differences compared to control groups. Furthermore, immunohistochemical analysis revealed a significant reduction in iNOS labeling in the brains of mice treated with NBV chlorhydrate, indicating a decrease in nitric oxide production compared to control groups. These findings suggest NBV's potential as a promising candidate for toxoplasmosis treatment, highlighting its ability to reduce parasite burden and protect neuronal integrity. Further research is warranted to elucidate NBV's mechanisms of action and its clinical application in managing toxoplasmosis.

Overexpression and extra-mitochondrial localization of the chaperonin Hsp60 in ameloblastoma

OBJECTIVES

Ameloblastoma is an odontogenic neoplasm of the mandible and maxilla with various histological types and subtypes. It has been reported that some ameloblastomas could arise from dentigerous cyst walls; thus, the development of ameloblastoma from dentigerous cysts may be due to differential protein expression. Our aim was to identify a membrane protein that is differentially expressed in ameloblastomas with respect to dentigerous cysts.

METHODS

We analyzed the SDS-PAGE profiles of membrane proteins from ameloblastomas and dentigerous cysts. The protein in a band present in the ameloblastoma sample, but apparently absent in the dentigerous cyst sample was identified via mass spectrometry as the chaperonin Hsp60. We used western blotting and immunohistochemistry to analyze its overexpression and localization in ameloblastoma.

RESULTS

We found a differential band of 95 kDa in the membrane proteins of ameloblastoma. In this band, the chaperonin Hsp60 was identified, and its overexpression was corroborated using western blotting and immunohistochemistry. Hsp60 was localized in the plasma membrane of all ameloblastoma samples studied; in addition, it was found in the cell nucleus of the plexiform subtype of conventional ameloblastoma.

CONCLUSIONS

Our results suggest that Hsp60 may be involved in ameloblastoma development, and could therefore be a potential therapeutic target for ameloblastoma treatment.

Differential Expression of Heat Shock Protein 27 in Oral Epithelial Dysplasias and Squamous Cell Carcinoma

Background:

Oral squamous cell carcinoma (OSCC) is the most devastating neoplasm with dramatic increase in morbidity and mortality. The detection and prognostic evaluation of precancerous lesions could aid in early control of cancer. Heat shock protein (HSP) 27 has found to be a biomarker and therapeutic target in different types of cancer.

Aim:

This study aims to investigate the role of HSP 27 as prognostic molecular indicator of malignant transformation in oral epithelial dysplasias.

Materials and Methods:

Thirty samples of epithelial dysplasia (10 mild dysplasia, 10 moderate dysplasia, and 10 severe dysplasia/carcinoma in situ cases), 10 samples each of well-differentiated OSCC and normal oral mucosa were routinely processed, formalin-fixed, paraffin-embedded, and analyzed for HSP27 expression by immunohistochemistry. Statistical analysis was done by one way-ANOVA and Mann–Whitney test to assess the differences between two individual groups.

Results:

Normal mucosa showed intense, but nonuniform, expression of HSP27. An initial decline was noted in dysplasias. A significant correlation of HSP27 expression was observed with the severity of dysplasia and well-differentiated OSCC (P < 0.05).

Conclusion:

Low HSP 27 expression can be considered as early molecular indicator of initial dysplastic change in normal mucosa. An overexpression of HSP 27 in clinically and histologically confirmed dysplasia could indicate likely transformation to well-differentiated OSCC and could be of prognostic value. However, further studies with a larger sample size are required to confirm the role of HSP 27 as predictive indicator.

Production and physiological role of NO in the oral cavity

Nitric oxide (NO) is a free radical which is produced from a wide variety of cells and tissues in the human body. NO is involved in the regulation of many physiological processes, such as vascular relaxation, neurotransmission, immune regulation, and cell death. NO is generated by nitric oxide synthase (NOS), which has three identified isoforms: neuronal type NOS (nNOS), endothelial type NOS (eNOS), and inducible type NOS (iNOS). Different isoforms are expressed depending on the organs, tissues, and cells, and investigation of the types and functions of enzymes expressed in various tissues is underway. The oral cavity is a space in which marked changes have been detected in NO levels, and each tissue is constantly influenced by NO. NO is a component of saliva and is produced by oral bacteria in the oral cavity and released by NOS expressed in oral mucosa. NOS isoforms expressed under normal conditions differ among the oral organs. In addition, the overexpression of NOS was involved in carcinogenesis and tumor growth progression. This review summarized the expression of NOS and functions of NO in oral cavity organs, and their roles in diseases and the influences of treatments.

HSP70 expression in dentigerous cyst, odontogenic keratocyst, and ameloblastoma

Heat shock proteins (HSPs) work as molecular chaperones that can assist cells to deal with stressful situations. Members of the HSP70 family can regulate cell growth and transformation and are involved in the maintenance of cellular homeostasis. In view of the distinct clinical behavior of odontogenic lesions, the objective of the present study was to investigate the immunohistochemical expression of HSP70 in these lesions. In this study, 70 formalin-fixed paraffin-embedded tissue blocks of odontogenic lesion-16 unicystic ameloblastomas (UAs), 17 solid ameloblastomas (SAs), 18 odontogenic keratocysts (OKCs), and 19 dentigerous cysts (DCs)-were reviewed by immunohistochemistry for HSP70 staining. In this study, HSP70 immunostaining was evident in all groups of the specimen. Mean percentage of HSP70 staining in SAs (84.2 ± 11.3) and OKCs (83.4 ± 6.8) were significantly higher than UAs (64.4 ± 9.8) and DCs (12.6 ± 10.2) (p = 0.00). But, there was no statistically significant difference between HSP70 expression in SAs and OKCs. The result of this study proposes that high expression rate of HSP70 has a role in the pathogenesis of ameloblastoma and OKC and is one of the reasons for the aggressive behavior of ameloblastoma and high recurrence role of OKC, reinforcing the classification of OKC as an odontogenic tumor.

Expression of inducible nitric oxide synthase in keratocystic odontogenic tumour and variants of ameloblastoma - a comparative study

INTRODUCTION

The odontogenic keratocyst (OKC) is a histopathologiocally and behaviourally unique and specific entity. It is the most aggressive and recurrent of all the cysts and shows characteristics resembling both cyst and a tumour. The unique nature of OKC and the recent shift of OKC as a tumour made us evaluate yet another factor, Inducible nitric oxide synthase an (iNos) enzyme which has been implicated in the tumourigenesis of various neoplasms. Aims and Objects: The objective of the study was to analyse and compare the immunohistochemical expression of iNOS in odontogenic keratocysts (OKC's) in variants of ameloblastoma affecting the oral cavity, to determine the neoplastic potential of OKC and to reinforce the classification of OKC as keratocystic odontogenic tumour.

MATERIALS AND METHODS

Thirty two specimens, eight specimens each in OKC, follicular ameloblastoma, plexiform ameloblastoma and unicystic ameloblastoma, taken from the Oral Pathology Department were randomly selected for this study and were evaluated for epithelial expression of iNOS by immunohistochemistry Results: Epithelial immunoreactivity to iNOS was strongly positive in 93.5% of follicular ameloblastomas, 68.7% of plexiform ameloblastomas, 66.9% of odontogenic keratocysts and 66.2% of unicystic ameloblastomas.

CONCLUSION

iNOS may be an important marker involved in the biological behaviour of OKC. Furthermore the presence of increased expression of iNOS in Follicular ameloblastomas followed by Plexiform ameloblastomas, OKCs and Unicystic ameloblastomas is yet another evidence to support that OKC could be considered as a neoplasm.

Heat shock protein27 expression and cell differentiation in ameloblastomas

The expression of HSP27 and some CKs were examined the 40 cases of typical solid/multicystic ameloblastoma using immunohistochemical techniques. In order to examine the relevance of HSP in cell differentiation, we focused on the cytoskeletal expression of CK. CK19 is a marker of typical odontogenic epithelium widely observed in follicular and plexiform types of ameloblastomas. Since staining with CK14 is one of the measures of the differentiation potential of squamous cells and is extensively expressed in both follicular and plexiform types, it implies that squamous differentiation of each type can occur. CK8 was strongly detected in tumor nests in plexiform type but weakly detected in follicular type. It was considered that the expression of HSP27 in plexiform type correlated with the expression of CK8 suggesting that HSP27 might have regulated the expression of CK8.

Quantitative and qualitative evaluation of iNOS expression in turbot (Psetta maxima) infected with Enteromyxum scophthalmi

Enteromyxum scophthalmi is the causative agent of turbot enteromyxosis, an intestinal parasitisation that produces severe desquamative enteritis leading to a cachectic syndrome and eventually the death. It is well known the importance of the innate immune response against parasites in fish, with the release of antimicrobial substances such as reactive oxygen and nitrogen species, produced by the inducible nitric oxide synthase (iNOS). This enzyme is mainly found in phagocytes, but also in structural cells from the intestinal mucosa. The aim of this study was to characterize iNOS in intestine and lymphohaematopoietic organs (spleen and anterior kidney) of turbot by means of immunohistochemistry in order to assess the possible changes of this enzyme through the infection. The presence of the enzyme was evaluated in control and E. scophthalmi-infected turbot. The results showed immunoreactivity in the apical border of enterocytes and mild staining of goblet cells in both control and infected turbot although it was more evident and widespread in infected turbot compared to control. Moderate numbers of iNOS+ cells were present in the lamina propria-submucosa of fish which presented moderate and severe inflammatory infiltrates at this level. In spleen and kidney, iNOS+ cells were scattered through the parenchyma and, in severely infected fish, tended to be allocated near the vascular structures and melano-macrophage centres. The number of positive cells at the lymphohaematopoietic organs was significantly higher in infected turbot and increased as infection progressed. The increase in the expression of iNOS in the tissues of E. scophthalmi-infected turbot was more evident in individuals with severer lesions. The measurement of the levels of iNOS during turbot enteromyxosis reveals a possibly delayed response that would not able to eliminate the parasites but would exacerbate mucosal injury.

Pathological changes and immunoexpression of p63 gene in dental follicles of asymptomatic impacted lower third molars: an immunohistochemical study

OBJECTIVE

The aim of this study was to examine the pathologic changes and immunoexpressivity of p63 gene in dental follicles (DFs) of asymptomatic partially and completely impacted lower third molars.

STUDY DESIGN

Clinical and radiologic examinations included 50 DFs with no signs of abnormal radiolucency (follicular space <2.5 mm), taken from 50 patients.

RESULTS

Histopathologic examinations of the specimens revealed 47 normal dental follicular tissues, 1 ameloblastoma, and 2 dentigerous cysts. p63 Immunoexpressivity was stronger in the DFs of the group with completely impacted teeth (64%),than it was in the case of DFs of the group with partially impacted teeth (40%).

CONCLUSIONS

Stronger p63 gene immunoexpression in the group with completely impacted teeth might be a consequence of bigger number of stem cells than it is in the case of the group with partially impacted teeth. This study also supports prophylactic removal of impacted teeth because of the development of pathologies associated with them.

iNOS expression in oral and gastrointestinal tract mucosa

It is known that the overproduction of nitric oxide (NO) by nitric oxide synthase (NOS) occurs during the progression of various inflammatory diseases in intestinal tract. NOS inhibitors or inducible nitric oxide synthase (iNOS) gene expression inhibitors should be considered as potential anti-inflammatory agents, as NO synthesized by iNOS is related to various pathophysiological processes including inflammation. In order to understand the relationship between iNOS and pathological reactions such as the inflammatory process and malign transformation clearly, the existence and amount of constitutive expression should be determined. It is crucial to comprehend the harmful and protective amounts of iNOS expressions in order to clarify the relationship between iNOS and pathological processes. Evidently, only after this inspection is it possible to utilize iNOS as a marker and treatment instrument during the diagnosis and treatment of malign transformation and the inflammatory process.

Altered immunolocalization of heat-shock proteins in human peri-implant gingiva

It has been suggested that heat-shock proteins (HSPs) might be involved in autoimmune disease mechanisms in humans, considering the high degree of sequence homology between bacterial and human HSPs. Several authors have postulated that HSPs might be involved in periodontal disease processes, but not specifically in peri-implantitis. Consequently, using immunohistochemical techniques, we studied the distribution of HSP25, HSP32, HSP60 and HSP72 in three groups of patients: (1) subjects with natural teeth (healthy periodontal tissue), (2) subjects with normal peri-implant mucosa and (3) subjects with clinically evident peri-implantitis. The immunolabelling for HSP25 and HSP60 was increased in the peri-implantitis group HSP32 immunolabelling slightly decreased in peri-implant and peri-implantitis gingiva. Labelling for HSP72 was undetectable in all three groups. In conclusion, we observed in peri-implantitis a clearly enhanced immunolabelling of two specific HSPs, HSP25 and HSP60, restricted to gingival epithelium and this could indicate a signal of local altered homeostasis.

Heat shock proteins in cancer: diagnostic, prognostic, predictive, and treatment implications

Heat shock proteins (Hsps) are overexpressed in a wide range of human cancers and are implicated in tumor cell proliferation, differentiation, invasion, metastasis, death, and recognition by the immune system. We review the current status of the role of Hsp expression in cancer with special emphasis on the clinical setting. Although Hsp levels are not informative at the diagnostic level, they are useful biomarkers for carcinogenesis in some tissues and signal the degree of differentiation and the aggressiveness of some cancers. In addition, the circulating levels of Hsp and anti-Hsp antibodies in cancer patients may be useful in tumor diagnosis. Furthermore, several Hsp are implicated with the prognosis of specific cancers, most notably Hsp27, whose expression is associated with poor prognosis in gastric, liver, and prostate carcinoma, and osteosarcomas, and Hsp70, which is correlated with poor prognosis in breast, endometrial, uterine cervical, and bladder carcinomas. Increased Hsp expression may also predict the response to some anticancer treatments. For example, Hsp27 and Hsp70 are implicated in resistance to chemotherapy in breast cancer, Hsp27 predicts a poor response to chemotherapy in leukemia patients, whereas Hsp70 expression predicts a better response to chemotherapy in osteosarcomas. Implication of Hsp in tumor progression and response to therapy has led to its successful targeting in therapy by 2 main strategies, including: (1) pharmacological modification of Hsp expression or molecular chaperone activity and (2) use of Hsps in anticancer vaccines, exploiting their ability to act as immunological adjuvants. In conclusion, the present times are of importance for the field of Hsps in cancer, with great contributions to both basic and clinical cancer research.

Subcellular and Functional Proteomic Analysis of the Cellular Responses Induced by Helicobacter pylori

Helicobacter pylori infection is a crucial factor in the pathogenesis of several digestive disorders, including peptic ulcers, chronic gastritis, and gastric cancer. Moreover H. pylori induces disease-specific protein expression in gastric epithelial cells. The aim of the present study was to characterize proteins differentially expressed in H. pylori-infected gastric epithelial AGS cells. An in vitro model was established using a multiplicity of infection of 100 and evaluating the effectiveness of H. pylori infection by functional analyses. Changes in protein patterns were identified using a proteomic approach consisting of two-dimensional fluorescence difference gel electrophoresis and mass spectrometry. The expression of many proteins was found to be altered, and 28 of these were identified and classified as protein synthesis- and folding-related proteins, cytoskeleton proteins, metabolic enzymes, transcription- and translation-related proteins, angiogenesis/metastasis-related proteins, cell communication/signal transduction-related proteins, or others (oxygen-regulated protein and oncoprotein). The expression profiles of eight of these proteins, laminin gamma-1 chain precursor, valosin-containing protein, heat shock 70-kDa protein, mitochondrial matrix protein P1, FK506-binding protein 4, T-complex protein 1, enolase alpha, and 14-3-3 beta were further examined in cancerous and paired surrounding normal tissues by immunoblot assay and immunohistochemical staining to identify molecular targets that may be involved in the pathogenesis of H. pylori-induced gastric diseases. On the basis of our results, valosin-containing protein, mitochondrial matrix protein P1, T-complex protein 1, enolase alpha, and 14-3-3 beta may play a crucial role in H. pylori-induced gastric carcinogenesis by mediating antiapoptotic and proliferative responses.

Detection of mitochondria-mediated apoptosis signaling molecules in ameloblastomas

BACKGROUND

To investigate the roles of the apoptosis signaling pathway mediated by mitochondria in oncogenesis and cytodifferentiation of odontogenic tumors, expression of pathway signaling molecules was analyzed in ameloblastomas as well as in tooth germs.

METHODS

Tissue specimens of 12 tooth germs, 41 benign ameloblastomas, and five malignant ameloblastomas were examined by reverse transcriptase polymerase chain reaction (RT-PCR) and immunohistochemistry to determine the expression of cytochrome c, apoptotic protease-activating factor-1 (APAF-1), caspase-9, and apoptosis-inducing factor (AIF).

RESULTS

The mRNA expression of APAF-1, caspase-9, and AIF was detected in all samples of normal and neoplastic odontogenic tissues. Immunohistochemical reactivity for cytochrome c, APAF-1, caspase-9, and AIF was detected in both normal and neoplastic odontogenic tissues. Expression of cytochrome c and AIF was evident in odontogenic epithelial cells neighboring the basement membrane, and APAF-1 and caspase-9 were detected in most odontogenic epithelial cells. Immunoreactivity for cytochrome c in tooth germs was slightly weaker than that in benign and malignant ameloblastomas. Keratinizing cells in acanthomatous ameloblastomas and granular cells in granular cell ameloblastomas showed a decrease or loss of immunoreactivity for these mitochondria-mediated apoptosis signaling molecules. Expression of AIF was obviously low in ameloblastic carcinomas.

CONCLUSION

Expression of cytochrome c, APAF-1, caspase-9, and AIF in tooth germs and ameloblastomas suggests that the mitochondria-mediated apoptotic pathway has a role in apoptotic cell death of normal and neoplastic odontogenic epithelium. Expression of these mitochondrial apoptosis signaling molecules might be involved in oncogenesis, cytodifferentiation, and malignant transformation of odontogenic epithelium.

Apoptosis in normal and diseased oral tissues

Apoptotic cell death plays an important role in maintenance of the normal physiological state and in the pathogenesis of diseases in the body. Over the last three decades the molecular mechanisms of apoptosis have been unravelled leading to development of novel therapeutic approaches. This paper aims to present current knowledge of the role of apoptosis in normal oral tissues and in the development of oral diseases.

Myofibroblasts in stroma of odontogenic cysts and tumors can contribute to variations in the biological behavior of lesions

Stromal myofibroblasts (MF) have the potential to facilitate progression of neoplastic epithelial lesions that could contribute to their biological behavior. To assess immunohistochemically the frequency of stromal MF in different odontogenic cysts and tumors and correlate it to their aggressive biological behavior. The study included cases of dentigerous cyst (DC, n = 7), odontogenic keratocyst-parakeratinized type (OKC-P, n = 8), orthokeratinized type (OKC-O, n = 9), ameloblastic fibroma/fibro-odontoma (AMF/O, n = 11), unicystic ameloblastoma (UAM, n = 6), and solid ameloblastoma (SAM, n = 7). Cases of oral squamous cell carcinoma (SCC, n = 5) served as control. Myofibroblast frequency was assessed as the number of alpha smooth muscle actin (alphaSMA)-positive stromal cells in 10 high-power fields, presented as the mean number of positive cells per field. Counts showed that mean number of positive cells in OKC-P (25.7+/-11.4) was significantly higher than in DC (8.7+/-11.6) (p = 0.024) and in SAM (29+/-7) it was significantly higher than in UAM (14.9+/-4.9) and AMF/O (5.6+/-7.5) (p < 0.001). Counts in OKC-P and SAM were not significantly different from SCC (21.3+/-5.3) (p > 0.05). The high frequency of stromal MF in known aggressive odontogenic lesions, such as OKC-P and SAM, implies that MF can contribute to the biological behavior of these odontogenic lesions. Various pharmacological agents that control stromal MF can be used as an aid to reduce extensive and mutilating surgery in cases of remarkably aggressive odontogenic lesions.

Expression of tumor necrosis factor alpha, TNF-related apoptosis-inducing ligand, and their associated molecules in ameloblastomas

BACKGROUND

To clarify the roles of the apoptosis signaling pathway mediated by death receptors in oncogenesis and cytodifferentiation of odontogenic tumors, expression of tumor necrosis factor alpha (TNFalpha), TNF-related apoptosis-inducing ligand (TRAIL), and their associated molecules was analyzed in ameloblastomas as well as in tooth germs.

METHODS

Tissue specimens of 10 tooth germs, 40 benign ameloblastomas, and five malignant ameloblastomas were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) and immunohistochemistry to determine the expression of TNFalpha, TNF receptor I (TNFRI), TRAIL, TRAIL receptor 1 (TRAIL-R1), TRAIL-R2, caspase-8, and nuclear factor-kappaB (NF-kappaB).

RESULTS

Expression of TNFalpha, TNFRI, TRAIL, TRAIL-R1, TRAIL-R2, and NF-kappaB mRNA was detected in most samples of normal and neoplastic odontogenic tissues. Expression of caspase-8 mRNA was identified in six of 33 ameloblastomas, but not in 10 tooth germs or one malignant ameloblastoma. Immunohistochemical reactivity for TNFalpha, TRAIL, their receptors, and NF-kappaB was detected in both normal and neoplastic odontogenic tissues. Epithelial expression of TNFalpha was focal in about 50% of tooth germs and ameloblastomas, and TNFalpha expression in neoplastic cells was significantly higher in follicular ameloblastomas than in plexiform ameloblastomas. TRAIL reactivity was evident in epithelial cells neighboring the basement membrane. Receptors for TNFalpha and TRAIL were diffusely expressed in both normal and neoplastic odontogenic epithelium. Expression of caspase-8 was found in some neoplastic cells in three of 37 ameloblastomas, but not in 10 tooth germs or five malignant ameloblastomas. Nuclear NF-kappaB expression was much lower than cytoplasmic expression in both normal and neoplastic odontogenic epithelium.

CONCLUSION

Expression of TNFalpha, TRAIL, and their receptors in tooth germs and ameloblastomas suggests that these death factors might be involved in cytodifferentiation of odontogenic epithelium and tissue structuring of ameloblastomas. Expression of caspase-8 and NF-kappaB suggests that signaling of TNFalpha and TRAIL minimally affects the biological properties of odontogenic epithelial components.

Immunolocalization of heat shock protein 27 in developing jaw bones and tooth germs of human fetuses

27 kDa Heat shock protein (Hsp27), which is also identified as p29 estrogen-receptor associated protein, plays a crucial role in specific growth stages. It also seems to be involved in the balance between differentiation and apoptosis. To determine whether Hsp27 is involved during craniofacial development and odontogenesis, its expression was studied through immunohistochemistry of developing jaw bone as well as the odontogenesis of heads from human fetuses. Formalin-fixed paraffin-embedded specimens of 7 human fetuses (3 female, 4 male), obtained from miscarriages occurring between the 9th and 16th weeks of pregnancy, were examined by using a monoclonal antibody against Hsp27. Staining intensity (weak, +; moderate, ++; strong, +++) was evaluated semiquantitatively. The sample slice was cut through a coronal plane, which included eyes, nasal cavities, tongue, and primitive dental lamina with tooth germs. A transient and spatially restricted expression of Hsp27 in developing human jaw bones and teeth was observed. Osteoblasts around the uncalcified bone matrix showed Hsp27 immunoreaction products (+++), whereas osteocytes were not immunolabeled. In mandibular condyle, immunolabeling was restricted to hypertrophic chondrocytes (++). In developing tooth germs, Hsp27 immunostaining was detected throughout the bud (+++). At the early cap stage, a strong immunolabeling for Hsp27 was seen in the dental lamina (+++), and a moderate staining was seen in the outer dental epithelium (++). At the late cap stage, Hsp27 expression was detected in the outer dental epithelium (++) as well as in the cells of the future stellate reticulum (++). The spatiotemporal-restricted expression of Hsp27 in craniofacial bones during development suggests that this protein could be involved in the balance between differentiation and apoptosis, by modulating the viability of osteoblasts and chondrocytes. The specific regional and temporal expression patterns of Hsp27 during tooth development sustains that this small Hsp might be related to the morphogenesis and cytodifferentiation processes of tooth germs.

Effects of lipopolysaccharide with L-arginine on proliferation and apoptosis of human hepatocellular carcinomacell line Bel-7402

AIM: To study the effect of endogenous nitric oxide (NO) on the proliferation and apoptosis in human liver carcinoma cell line 7402 through regulation of the speed limit enzyme and the concentration of substrate in the process of No production.

METHODS: The speed limit enzyme in the process of NO production in 7402 cell is inducible nitric oxide synthase (iNOS), and its substrate is L-arginine (L-Arg).The cells were cultured in the Dulbecco's modified Eagle medium, which was without L-Arg. Different concentration of L-Arg was added into the culture medium and lipopolysaccharide (LPS) of 100 ng/L was added at the same time. MTT method was adopted to describe the proliferation of the cells. Immunohistochemical method was performed to determine the expression of iNOS. The TUNEL method was used to detect the apoptosis in situ.

RESULTS: Without change of the expression and activity of iNOS, L-Arg of 0.625 mmol/L produced NO with low concentration, it could promote the proliferation of the cells. On the contrary, L-Arg of 2.5 mmol/L inhibited the proliferation of the cells and improved the apoptotic rate of the cells. LPS of 100 ng/L could promote the expression and activity of iNOS in the cells. The production of NO in unit time was increased if the substrate was enough.

CONCLUSION: Low concentration of NO promotes the proliferation of the cells. High concentration of NO can inhibit the proliferation and promote the apoptosis of the cells. Increasing the production of endogenous NO by stimulating the expression and activity of its own iNOS is an effective way to inhibit the cells proliferation and promote its apoptosis.

Expression of survivin and X chromosome-linked inhibitor of apoptosis protein in ameloblastomas

To clarify the role of apoptosis in oncogenesis and cytodifferentiation of odontogenic epithelium, expression of survivin and X chromosome-linked inhibitor of apoptosis protein (XIAP), inhibitor of apoptosis protein (IAP) family proteins, was examined in tooth germs and in benign and malignant ameloblastomas by means of immunohistochemistry and reverse-transcription polymerase chain reaction. Immunoreactivity for survivin and XIAP was detected in developing and neoplastic odontogenic epithelium. In tooth germs, survivin expression was evident in inner enamel epithelium. Follicular, plexiform and metastasizing ameloblastomas showed survivin reactivity chiefly in neoplastic cells neighboring the basement membrane, and most neoplastic cells in basal cell and desmoplastic ameloblastomas and ameloblastic carcinomas were positive for survivin. Survivin mRNA levels were slightly higher in ameloblastomas than in tooth germs, suggesting that elevation of survivin expression might be involved in oncogenesis of odontogenic epithelium. Immunoreactivity for XIAP was detected in most odontogenic epithelial cells in tooth germs and in benign and malignant ameloblastomas, and XIAP mRNA levels were significantly higher in follicular ameloblastomas than in plexiform ameloblastomas. The expression of survivin and XIAP in odontogenic tissues suggests that these IAP family proteins contribute to the biological properties of ameloblastomas, such as cell survival, proliferation, differentiation and tissue structuring, as well as to cellular regulation during tooth development.