Apoptosis and cell cycle aberrations in epithelial odontogenic lesions: An evidence by the expression of p53, Bcl-2 and Bax

Does YAP influence cell proliferation and apoptosis in benign epithelial odontogenic lesions?

OBJECTIVE

To analyze the immunohistochemical expression of YAP and its correlation with markers involved in cell proliferation and apoptosis in benign epithelial odontogenic lesions.

STUDY DESIGN

The sample consisted of 95 cases of odontogenic lesions (25 dentigerous cysts, 30 non-syndromic odontogenic keratocysts, 30 conventional ameloblastomas, and 10 unicystic ameloblastomas) and 10 dental follicles used as normal odontogenic tissue. The histological sections were submitted to immunohistochemistry with YAP, cyclin D1, Ki-67, and Bcl-2 antibodies. Immunoexpression was analyzed qualitatively and quantitatively using an adapted method. The collected data were analyzed descriptively and statistically (p ≤ 0.05).

RESULTS

The highest YAP expression was observed in odontogenic keratocysts, followed by unicystic ameloblastomas and conventional ameloblastomas, which exhibited moderate immunoreactivity predominantly in peripheral cells. Furthermore, significant differences in YAP immunoexpression were observed between the groups analyzed, with significant positive correlations between YAP and cyclin D1 in dentigerous cysts and unicystic ameloblastomas and between YAP and Ki-67 in unicystic ameloblastomas (p < 0.05). However, there were no statistically significant correlations between YAP and Bcl-2 immunoexpression in the groups studied.

CONCLUSION

YAP may influence epithelial cell proliferation in odontogenic cysts and tumors, suggesting its possible participation in the progression of the odontogenic lesions studied.

Aberrant immunoexpression of p53 tumour-suppressor and Bcl-2 family proteins (Bcl-2 and Bax) in ameloblastomas and odontogenic keratocysts

Background

The growth of ameloblastomas (odontogenic tumours) and odontogenic keratocyst (OKC) (developmental cyst) is associated with the expression of proteins related to cell survival and apoptosis. Bcl-2-associated protein X (Bax) and the tumour suppressor protein p53 collectively promote p53-mediated apoptosis. This study aimed to assess the immunohistochemical expression of p53, Bcl-2 and Bax in conventional ameloblastoma (CA), unicystic ameloblastoma (UA) types, and OKC sporadic (OKC-NS/S) and syndromic (OKC-NBSCC).

Material and Methods

Paraffinized blocks of CA (n=18), UA (n=15), OKC-NS/S (n=18) and OKC-NBSCC (n=15) fixed in 10% formalin were used. After diagnosis, tissue specimens were stained by immunohistochemistry for p53, Bcl-2 and Bax marker. Stained cells were randomly counted in five high power fields. The data analysis was performed via Shapiro-Wilk test, ANOVA with Tukey's multiple comparisons or Kruskal-Wallis with Dunn's multiple comparisons. Statistical significance was defined as p<0.05.

Results

We did not observe differences between p53 expression in CA, mural UA (MUA), intraluminal/luminal UA (I/LUA), OKC-NS/S, and OKC-NBSCC (19.69%, 18.74%, 16.76%, 12.35% and 9.04%, respectively). Similar results were recognized for Bax expression in CA, MUA, I/LUA, OKC-NS/S, and OKC-NBSCC (33.72%, 34.95%, 22.94, 21.58% and 20.76%, respectively). However, we recognized significant differences between Bcl-2 expression in OKC-NS/S vs MUA, OKC-NS/S vs I/LUA, OKC-NS/S vs CA, OKC-NBSCC vs MUA, OKC-NBSCC vs I/LUA, and I/LUA vs CA. P53, Bcl-2 and Bax levels were higher in mural morphological areas versus intraluminal and luminal morphological areas in UA.

Conclusions

There is a tendency for an increased expression of p53, Bcl-2, and Bax proteins in CA, and mural proliferation of UA, compared to lesions with a cystic morphology, which could be associated with a local aggressive behaviour. Key words:p53, Bcl-2, Bax protein, apoptosis, odontogenic tumour, odontogenic cyst.

CDC7 Expression in Selected Odontogenic Tumors

Objectives. CDC7 is a serine-threonine kinase that plays a key role in initiating DNA replication. It has been implicated in the growth and invasion of many pathologic lesions and suggested as a diagnostic marker. The aim of this study was to evaluate CDC7 in some odontogenic tumors. Materials and Methods. In this cross-sectional study, 45 cases, including 19 ameloblastomas, 15 dentigerous cysts, 7 ameloblastic fibromas, and 4 adenomatoid odontogenic tumors (AOT), were studied immunohistochemically. ANOVA and post hoc methods were used for statistical analysis. Results. CDC7 expression was observed in 93% of tumors and all dentigerous cysts. The expression rate was low. The results showed a higher expression rate of CDC7 in ameloblastoma and ameloblastic fibroma compared to AOT ( $p=0.009$ and $p=0.048$ , respectively). Ameloblastoma and ameloblastic fibroma were not significantly different in CDC7 expression ( $p=0.6$ ). Conclusion. According to the results, the expression of the CDC7 protein in odontogenic tumors is low. The higher expression of CDC7 in ameloblastoma and ameloblastic fibroma in comparison with AOT confirms the hamartomatous growth of the latter, so it can be considered as a potential diagnostic marker. Future studies with a larger sample size are suggested to obtain a cut-off point for diagnostic purposes.

Decompression induces inflammation but do not modify cell proliferation and apoptosis in odontogenic keratocyst

BACKGROUND

Odontogenic keratocyst (OKC) is a development cyst, of odontogenic origin, that differs from other entities by its infiltrating and aggressive biological behavior. Among conservative treatments for large lesions, surgical decompression stands out, with a variable recurrence rate. Aim: To evaluate the histological effects of decompression treatment on OKC, including cell proliferation and apoptosis of epithelial cyst.

MATERIAL AND METHODS

21 OKC cases were included. Samples were taken before and after surgical decompression for histological evaluation and immunohistochemical staining of Ki-67, MCM4/7, Bax and Bcl2. Data were analyzed and compared using Student's t and Wilcoxon tests for related samples, and p values <0,05 were considered statistically significant.

RESULTS

After decompression treatment an increase in inflammation of the cystic wall (p=0,029), loss of parakeratinization of the epithelium (p=0,007) and absence of palisade cell distribution in the basal layer were observed (p=0,002). There were no statistically significant changes in the expression of Ki-67 (p=0,323), MCM4/7 (p=0,079), Bax (p=0,392) or Bcl-2 when compared before and after decompression.

CONCLUSIONS

Surgical decompression generates histological structural changes in OKC both in the epithelium and connective wall, however, these findings do not seem to alter induction of the cell cycle or epithelial apoptosis. Key words:Odontogenic keratocyst, MCM, Bax, Bcl2, Ki-67, apoptosis, decompression.

Apoptosis-antagonizing transcription factor is involved in rat post-traumatic epilepsy pathogenesis

The present study aimed to explore the pathogenesis behind post-traumatic epilepsy (PTE). In the present study, a chloride ferric injection-induced rat PTE model was established. The expression levels of apoptosis-antagonizing transcription factor (AATF), cleaved caspase-3, p53, Bcl-2 and Bax were measured by western blotting or immunofluorescence staining (IF). The expression of AATF in vivo was downregulated by microinjection of lentiviral-mediated short-hairpin RNA. Compared with control and sham groups, at day 5 after PTE, neuron apoptosis was significantly increased and the expression levels of AATF, p53, cleaved caspase-3 and Bax were significantly upregulated. In addition, IF revealed co-localization of AATF and cleaved caspase-3 in the cortex. Additionally, AATF was expressed mainly in neurons and astrocytes. Following AATF inhibition, the expression levels of p53 and cleaved caspase-3 were significantly reduced as compared with the control group. Taken together, these findings suggested that following PTE, AATF is involved in neuronal apoptosis and may serve as a potential target for its alleviation.

The role of oxidative stress-mediated apoptosis in the pathogenesis of uric acid nephropathy

Objective: By copying the uric acid nephropathy rat model, the oxidative stress injury of mitochondria was caused in renal tubular epithelial cells and the relationship between the injury and the induction of cell apoptosis was identified.

Methods: All rats were randomly divided into NC (normal control, NC) group, HUA (high uric acid, HUA) group and GSH (reductive glutathione, GSH) group. The values were quantitatively tested in the kidney tissues, including 24-h urinary protein quantity, serum creatinine, blood uric acid, the MDA (malondialdehyde, MDA) and SOD (superoxide dismutase, SOD) oxidative stress indicators. The expression of p53, Bax and caspase-9/-3 were detected by immunoblotting. TUNEL assays were used to detect the apoptosis of renal tubular epithelial cells.

Result: In HUA and GSH groups, the 24-h urinary protein(24UTP), serum creatinine, and blood uric acid increased gradually with the increase of the replication cycle and the increase was significant compared to the NC group (p < .05). Compared to the NC group, MDA increased whereas SOD decreased. The expression of apoptotic proteins, such as p53, Bax, and caspase-9/-3 in the mitochondria was significantly different (p < .05). TUNEL assay revealed that the renal tubular epithelial cells in HUA group were largely apoptotic, whereas the GSH group improved significantly.

Conclusion: Mitochondria incurred the substantial damage due to being in a state of oxidative stress, which was the primary cause of apoptosis in the renal tubule epithelial cells. GSH exhibited the effective resistance to the influence of oxidative stress and can restore the damage in the renal tubular epithelial cells.