Tumor cell-intrinsic programmed death-ligand 1 (PD-L1) signals mediate tumor initiation, progression and metastasis, but their effects in ameloblastoma (AM) have not been reported. In this comprehensive study, we observed marked upregulation of PD-L1 in AM tissues and revealed the robust correlation between elevated PD-L1 expression and increased tumor growth and recurrence rates. Notably, we found that PD-L1 overexpression markedly increased self-renewal capacity and promoted tumorigenic processes and invasion in hTERT⁺-AM cells, whereas genetic ablation of PD-L1 exerted opposing inhibitory effects. By performing high-resolution single-cell profiling and thorough immunohistochemical analyses in AM patients, we delineated the intricate cellular landscape and elucidated the mechanisms underlying the aggressive phenotype and unfavorable prognosis of these tumors. Our findings revealed that hTERT⁺-AM cells with upregulated PD-L1 expression exhibit increased proliferative potential and stem-like attributes and undergo partial epithelial‒mesenchymal transition. This phenotypic shift is induced by the activation of the PI3K-AKT-mTOR signaling axis; thus, this study revealed a crucial regulatory mechanism that fuels tumor growth and recurrence. Importantly, targeted inhibition of the PD-L1-PI3K-AKT-mTOR signaling axis significantly suppressed the growth of AM patient-derived tumor organoids, highlighting the potential of PD-L1 blockade as a promising therapeutic approach for AM.
Ameloblastoma/metabolism* ; Humans ; B7-H1 Antigen/metabolism* ; Neoplasm Recurrence, Local/pathology* ; Signal Transduction ; Cell Proliferation ; Up-Regulation ; TOR Serine-Threonine Kinases/metabolism* ; Proto-Oncogene Proteins c-akt/metabolism* ; Telomerase/metabolism* ; Jaw Neoplasms/metabolism* ; Epithelial-Mesenchymal Transition ; Animals ; Cell Line, Tumor ; Female ; Male

Odontogenic tumors are rare lesions with unknown etiopathogenesis. Most of them are benign, but local aggressiveness, infiltrative potential, and high recurrence rate characterize some entities. The MAP-kinase pathway activation can represent a primary critical event in odontogenic tumorigenesis. Especially, the BRAF V600E mutation has been involved in 80-90% of ameloblastic lesions, offering a biological rationale for developing new targeted therapies. The study aims to evaluate the BRAF V600E mutation in odontogenic lesions, comparing three different detection methods and focusing on the Sequenom MassARRAY System. 81 surgical samples of odontogenic lesions were subjected to immunohistochemical analysis, Sanger Sequencing, and Matrix-Assisted Laser Desorption/Ionization-Time of Flight mass spectrometry (Sequenom). The BRAF V600E mutation was revealed only in ameloblastoma samples. Moreover, the presence of BRAF V600E was significantly associated with the mandibular site (ρ = 0.627; P value <0.001) and the unicystic histotype (ρ = 0.299, P value <0.001). However, any significant difference of 10-years disease-free survival time was not revealed. Finally, Sequenom showed to be a 100% sensitive and 98.1% specific, suggesting its high-performance diagnostic accuracy. These results suggest the MAP-kinase pathway could contribute to ameloblastic tumorigenesis. Moreover, they could indicate the anatomical specificity of the driving mutations of mandibular ameloblastomas, providing a biological rational for developing new targeted therapies. Finally, the high diagnostic accuracy of Sequenom was confirmed.
Ameloblastoma/pathology* ; Carcinogenesis ; Humans ; Mitogen-Activated Protein Kinases/genetics* ; Mutation ; Odontogenic Tumors/pathology* ; Proto-Oncogene Proteins B-raf/metabolism* ; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

OBJECTIVETo study the expression of HOXC13 mRNA in ameloblastoma (AB), and to investigate its biological significance.

METHODSHOXC13 mRNA was examined in 47 cases of AB (primary AB 29 cases, recurrent AB 14 cases, malignant AB 4 cases). 2 cases of fibrous dysplasia of bone, 10 cases of keratocystic odontogenic tumor (KCOT) and 7 cases of normal oral mucosa were selected as control.

RESULTSThe positive rates of HOXC13 mRNA in AB, KCOT, and normal oral mucosa were 97.9% (46/47), 7/10 and 3/7, respectively. There was a significant difference among AB, OKC and normal mucosa (chi(2) = 21.665, P = 0.001). For HOXC13, the keratinizing cells and granulizing cells in AB were negative, some fibroblasts were positive, 2 cases of fibrous dysplasia of bone were positive.

CONCLUSIONSHOXC13 was highly expressed in AB. The expression of HOXC13 mRNA in AB had heterogeneity, which could improve the epithelial proliferation, and its loss may lead to the cornification and degeneration of epithelial cells.

Adolescent ; Adult ; Ameloblastoma ; genetics ; metabolism ; pathology ; Female ; Gene Expression ; Genes, Homeobox ; Homeodomain Proteins ; metabolism ; Humans ; Male ; Middle Aged ; Mouth Mucosa ; metabolism ; Odontogenic Tumors ; genetics ; metabolism ; RNA, Messenger ; metabolism ; Young Adult

OBJECTIVETo construct the eukaryotic expression vector of TIMP-2 gene and to explore its expression in human ameloblastoma cell in vitro.

METHODSThe aimed gene fragment was obtained by RT-PCR. And then, molecmicrolar cloning technology and enzyme digestion were used to connect the gene with the plasmid PcDNA3.1(+), which can be expressed in eukaryotic cells and a report gene: green fluorescent protein gene (GFP) was already existed in the plasmid. We named the eukaryotic expression vector, which contended our aimed gene TIMP-2 as well as report gene GFP, PcDNA3.1(+)/GFP-TIMP-2. The vector was identified by PCR analysis, EcoR I and Xho I restriction analysis and Sequence analysis. After the PcDNA3.1(+)/GFP-TIMP-2 was transfected into cultured human ameloblastoma cell, RT-PCR and Flow Cytometry (FCM) and Microscope wre respectively performed to evaluate the effect of transfection and expression.

RESULTSThe constructed vector PcDNA3.1(+)/GFP-TIMP-2 was proved correct by enzyme digestion and sequencing analysis. After PcDNA3.1(+)/GFP-TIMP-2 was trasnfected into cultured human ameloblastoma cell, the rate of transfection is 47.6% (Analysis report of FCM), the green fluorescence was found in plasm (observed with fluo-microwave), the expression of TIMP-2 mRNA was elevated 2.4 times compared with the control group.

CONCLUSIONSPcDNA3.1(+)/GFP-TIMP-2 was successfully constructed and it could be transfected into cultured human ameloblastoma cell. It may be benefit to further study of the relationship between the TIMP-2 gene and the behaviour of ameloblastoma.

Ameloblastoma ; genetics ; metabolism ; Genetic Vectors ; Green Fluorescent Proteins ; genetics ; metabolism ; Humans ; Jaw Neoplasms ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Tissue Inhibitor of Metalloproteinase-2 ; genetics ; metabolism ; Transfection ; Tumor Cells, Cultured

OBJECTIVETo investigate the expression of cyclin E mRNA, p21(WAF1) mRNA and p27(KIP1) protein in human ameloblastoma (AB), and to explore the clinical and biological characteristics of AB.

METHODSThe expression of cyclin E mRNA, p21(WAF1) mRNA and p27(KIP1) protein in 54 cases of human AB were detected by in situ hybridization or immunohistochemistry (SP method).

RESULTSThe positive expression rate of cyclin E mRNA in the cytoplasm or cell nucleus of AB was 66.7% (36/54). The expression of cyclin E mRNA increased with AB recurrence and malignant transformation, and the difference of expression among primary AB, recurrent AB, and malignant AB, was statistically significant. The positive expression ratio of cyclin E mRNA in OKC was 50.0% (8/16). The p21(WAF1) mRNA expression in the cytoplasm or cell nucleus of AB decreased, and the positive ratio was 22.6% (12/54) in AB, 37.5% (6/16) in OKC, respectively. The p27(KIP1) protein expression in the cell nucleus of AB was positive in a small number of cases, and the positive rate was 16.7% (9/54) in AB, 6.3% (1/16) in OKC, respectively.

CONCLUSIONSThe genesis and invasion of AB is associated with the cell proliferation and differentiation, and regulated by the higher expression of cyclin E and the lower expression of p21(WAF1) and p27(KIP1).

Adolescent ; Adult ; Aged ; Ameloblastoma ; metabolism ; pathology ; Child ; Cyclin E ; genetics ; metabolism ; Cyclin-Dependent Kinase Inhibitor p21 ; genetics ; metabolism ; Cyclin-Dependent Kinase Inhibitor p27 ; Female ; Humans ; Intracellular Signaling Peptides and Proteins ; genetics ; metabolism ; Jaw Neoplasms ; metabolism ; pathology ; Middle Aged ; Oncogene Proteins ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism ; Young Adult

OBJECTIVETo investigate the effect of bone resorption by odontogenic cysts and ameloblastomas in vitro.

METHODSFragments of odontogenic cysts (14 odontogenic keratocysts, 6 inflamed odontogenic keratocysts, 5 dentigerous cysts) and ameloblastomas (n = 7) were incubated in vitro for 24 h. The supernatant was then removed into the culture system of SD rat calvaria. After incubation (48 h), the calcium contents of the media were measured by atom spectrophotometer. The supernatant of odontogenic cysts and ameloblastomas was measured for the bone resorption related factors such as IL-6, TNF-alpha, PGE(2), bone Gla-containing protein (BGP) and calcitonin (CT) by a radioimmunoassay system.

RESULTSThe calcium released in the calvaria culture media by all the odontogenic lesions was significantly higher than that in the blank controls (P < 0.01). The inflamed odontogenic keratocyst group had a significantly higher calcium concentration than odontogenic keratocyst and ameloblastoma groups (P < 0.05). In addition, the concentration of IL-6, TNF-alpha, PGE(2) and CT in the culture media of all odontogenic lesions were significantly higher than that of the blank controls (P < 0.05). IL-6 concentration in the inflamed and non-inflamed odontogenic keratocyst groups were significantly higher than that of ameloblastoma group (P < 0.05). CT concentration in the inflamed odontogenic keratocyst was significantly higher than those of odontogenic keratocyst and dentigerous cyst groups (P < 0.05). Correlation and regression analysis showed that IL-6 was significantly correlated with the calcium content (P < 0.01).

CONCLUSIONSThe odontogenic lesions could promote bone resorption in vitro and it is likely to be related to some of the cytokines secreted by the lesions.

Ameloblastoma ; metabolism ; physiopathology ; Animals ; Bone Resorption ; Humans ; In Vitro Techniques ; Odontogenic Cysts ; metabolism ; physiopathology ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the expression of pRb and E2F-1, and the association between their expression and the activity of telomerase (hTERT) or cyclin E in human ameloblastoma (AB), and to explore the clinical biological characteristics of AB.

METHODSThe expressions of pRb, E2F-1, cyclin E and hTERT mRNA in human AB were detected by in situ hybridization or immunohistochemistry (SP method).

RESULTSThe positive expression ratio of pRb in the cell nucleus of AB was 20.4% (11/54). The positive ratio of E2F-1, cyclin E and hTERT mRNA was 92.6% (50/54), 66.7% (36/54) and 94.4% (51/54), respectively. With AB recurrence and malignant transformation, the expression of hTERT, E2F-1, cyclin E was up-regulated. hTERT and cyclin E or E2F-1 mRNA had high positive relation (Spearsman'r(s) = 1.000, P = 0.0001).

CONCLUSIONSThe regulatory pathway of Rb/E2F-1 is associated with the cell proliferation and in differentiation of AB. The activity or release of telomerase may be related to the lower expression of Rb and higher expression of E2F-1, and is up-regulated in G(1) late phase by cyclin E.

Adolescent ; Adult ; Aged ; Ameloblastoma ; metabolism ; pathology ; Child ; Cyclin E ; biosynthesis ; E2F1 Transcription Factor ; biosynthesis ; Female ; Humans ; Jaw Neoplasms ; metabolism ; pathology ; Male ; Middle Aged ; RNA, Messenger ; biosynthesis ; Retinoblastoma Protein ; biosynthesis ; Telomerase ; genetics ; metabolism

OBJECTIVETo study the oncogene transcriptor c-myc, stimulatory protein 1 (SP1) expression in ameloblastoma (AB) and their relation with telomerase reverse transcripase (hTERT), and to investigate the clinical biological characteristics of AB.

METHODSThe expression was observed in AB by in situ hybridization and SP method.

RESULTSThe positive rates of c-myc mRNA, hTERT mRNA and SP1 protein were 81.5% (44/54), 94.4% (51/54) and 83.3% (45/54), respectively. Their positive rates increased as AB recurred and transformed malignantly. A strong correlation was found between hTERT and c-myc, hTERT and SP1 (rs = 0.853, P < 0.001; rs = 0.900, P < 0.001).

CONCLUSIONActivity of telomerase plays an important role in the tumorigenesis development of AB. Increasing of hTERT expression may be related to c-myc and SP1. The expression of these three parameters has a significant correlation with the clinical biological characteristics of AB.

Ameloblastoma ; metabolism ; Humans ; Proto-Oncogene Proteins c-myc ; metabolism ; Sp1 Transcription Factor ; metabolism ; Telomerase ; metabolism

OBJECTIVETo study the expression of telomerase reverse transcriptase (hTERT) and bcl-2 in ameloblastoma (AB), METHODS: hTERT mRNA in 54 cases of AB (primary AB 31 cases, recurrent AB 17 cases, malignant AB 4 cases) and 7 cases of oral normal mucosa was detected by in situ hybridization, and bcl-2 by S-P method.

RESULTSThe expression of hTERT mRNA was negative or weak in normal oral mucosa (14.3%), moderate or strong in AB (94.4%). There was a significant difference in these two groups (P < 0.001). The difference between the expressions of hTERT in primary, recurrent and malignant AB was significant (P < 0.05). The positive ratio of bcl-2 in AB and normal oral mucosa was respectively 88.0%, 44.4%. There was a significant statistical difference in these two groups (P < 0.001). hTERT mRNA was stronger in recurred or malignantly transformed AB (P < 0.05).

CONCLUSIONThe expression of hTERT and bcl-2 is stronger in recurred or malignantly transformed AB, and it could be used as an indicator of AB prognosis. Telomerase activity and bcl-2 expression play an important role in genesis and development of AB.

Adolescent ; Adult ; Ameloblastoma ; enzymology ; metabolism ; Biomarkers, Tumor ; Child ; DNA-Binding Proteins ; Female ; Humans ; Jaw Neoplasms ; enzymology ; metabolism ; Male ; Middle Aged ; Neoplasm Recurrence, Local ; enzymology ; metabolism ; Proto-Oncogene Proteins c-bcl-2 ; biosynthesis ; genetics ; RNA, Messenger ; biosynthesis ; genetics ; Telomerase ; biosynthesis ; genetics

OBJECTIVEThe expression of Ki-67 antigen of ameloblastoma was examined in order to investigate the different proliferation activity of histological variants of ameloblastoma and its clinical significance.

METHODS70 cases of different histological specimen of ameloblastoma were analyzed by immunohistochemical method using Ki-67 antibody. The Label Index was calculated in percentage of Ki-67 positive cells after examined with an image analysis system.

RESULTSThe results showed that the Labeled Index in malignant ameloblastoma was the highest 14.72% +/- 2.87%. The Labeled Index in solid ameloblastoma was in the middle, among which the follicular 4.42% +/- 1.05% was higher than the plexiform 3.64% +/- 1.23%. The Labeled Index in mono-cystic ameloblastoma was the lowest 2.21% +/- 1.09%.

CONCLUSIONThe results demonstrated that the proliferation activity varied according to the histological pattern of ameloblastoma. The prognosis with different proliferation activity was also varied accordingly.

Ameloblastoma ; metabolism ; pathology ; Humans ; Image Processing, Computer-Assisted ; Jaw Neoplasms ; metabolism ; pathology ; Ki-67 Antigen ; biosynthesis ; Neoplasm Recurrence, Local ; Odontogenic Tumors ; metabolism ; pathology