PEBP1 Wardens Ferroptosis by Enabling Lipoxygenase Generation of Lipid Death Signals.

Ferroptosis is a form of programmed cell death that is pathogenic to several acute and chronic diseases and executed via oxygenation of polyunsaturated phosphatidylethanolamines (PE) by 15-lipoxygenases (15-LO) that normally use free polyunsaturated fatty acids as substrates. Mechanisms of the altered 15-LO substrate specificity are enigmatic. We sought a common ferroptosis regulator for 15LO. We discovered that PEBP1, a scaffold protein inhibitor of protein kinase cascades, complexes with two 15LO isoforms, 15LO1 and 15LO2, and changes their substrate competence to generate hydroperoxy-PE. Inadequate reduction of hydroperoxy-PE due to insufficiency or dysfunction of a selenoperoxidase, GPX4, leads to ferroptosis. We demonstrated the importance of PEBP1-dependent regulatory mechanisms of ferroptotic death in airway epithelial cells in asthma, kidney epithelial cells in renal failure, and cortical and hippocampal neurons in brain trauma. As master regulators of ferroptotic cell death with profound implications for human disease, PEBP1/15LO complexes represent a new target for drug discovery.

Discovering selective antiferroptotic inhibitors of the 15LOX/PEBP1 complex noninterfering with biosynthesis of lipid mediators.

Programmed ferroptotic death eliminates cells in all major organs and tissues with imbalanced redox metabolism due to overwhelming iron-catalyzed lipid peroxidation under insufficient control by thiols (Glutathione (GSH)). Ferroptosis has been associated with the pathogenesis of major chronic degenerative diseases and acute injuries of the brain, cardiovascular system, liver, kidneys, and other organs, and its manipulation offers a promising new strategy for anticancer therapy. This explains the high interest in designing new small-molecule-specific inhibitors against ferroptosis. Given the role of 15-lipoxygenase (15LOX) association with phosphatidylethanolamine (PE)-binding protein 1 (PEBP1) in initiating ferroptosis-specific peroxidation of polyunsaturated PE, we propose a strategy of discovering antiferroptotic agents as inhibitors of the 15LOX/PEBP1 catalytic complex rather than 15LOX alone. Here we designed, synthesized, and tested a customized library of 26 compounds using biochemical, molecular, and cell biology models along with redox lipidomic and computational analyses. We selected two lead compounds, FerroLOXIN-1 and 2, which effectively suppressed ferroptosis in vitro and in vivo without affecting the biosynthesis of pro-/anti-inflammatory lipid mediators in vivo. The effectiveness of these lead compounds is not due to radical scavenging or iron-chelation but results from their specific mechanisms of interaction with the 15LOX-2/PEBP1 complex, which either alters the binding pose of the substrate [eicosatetraenoyl-PE (ETE-PE)] in a nonproductive way or blocks the predominant oxygen channel thus preventing the catalysis of ETE-PE peroxidation. Our successful strategy may be adapted to the design of additional chemical libraries to reveal new ferroptosis-targeting therapeutic modalities.

Surgical Extrusion of Three Premolars to Re-establish the Biological Width: Case Series.

AIM: This case series was to describe the use of surgical extrusion for three different cases as a technique to re-establish the biological width in patients with insufficient crown height. BACKGROUND: Surgical extrusion serves as an important means to reestablishing a proper biological width. Such method provides an excellent alternative for the restoration of teeth with insufficient ferrule and ensuring a suitable dental restoration. CASES DESCRIPTIONS: This case series describes the management of three different cases with compromised teeth #25, #35, and #44, respectively. The approach involved the surgical extrusion of the compromised sites from subgingival to supragingival and the splinting of the teeth using a semi-rigid splint. A successful prognosis was observed on follow-up visits. CONCLUSION: This technique is a good alternative for general practitioners because of its easy implementation and time efficiency. In addition, the method requires less equipment and provides for adequate space for the re-establishment of biological width. CLINICAL SIGNIFICANCE: Such technique can re-establish a healthy biological width, the existing occlusion can be maintained without alterations, and it demonstrated the suitability of surgical extrusion technique in such clinical situations. Case selection is equally important. Cases with single-rooted teeth with fractures or caries in proximity to the marginal bone level without vertical root fractures generally provide positive outcomes on providing this treatment. How to cite this article: Boreak N, Al Moaleem MM, Zain AA, et al. Surgical Extrusion of Three Premolars to Re-establish the Biological Width: Case Series. J Contemp Dent Pract 2024;25(6):593-598.

Strikingly High Activity of 15-Lipoxygenase Towards Di-Polyunsaturated Arachidonoyl/Adrenoyl-Phosphatidylethanolamines Generates Peroxidation Signals of Ferroptotic Cell Death.

The vast majority of membrane phospholipids (PLs) include two asymmetrically positioned fatty acyls: oxidizable polyunsaturated fatty acids (PUFA) attached predominantly at the sn2 position, and non-oxidizable saturated/monounsaturated acids (SFA/MUFA) localized at the sn1 position. The peroxidation of PUFA-PLs, particularly sn2-arachidonoyl(AA)- and sn2-adrenoyl(AdA)-containing phosphatidylethanolamines (PE), has been associated with the execution of ferroptosis, a program of regulated cell death. There is a minor subpopulation (≈1-2 mol %) of doubly PUFA-acylated phospholipids (di-PUFA-PLs) whose role in ferroptosis remains enigmatic. Here we report that 15-lipoxygenase (15LOX) exhibits unexpectedly high pro-ferroptotic peroxidation activity towards di-PUFA-PEs. We revealed that peroxidation of several molecular species of di-PUFA-PEs occurred early in ferroptosis. Ferrostatin-1, a typical ferroptosis inhibitor, effectively prevented peroxidation of di-PUFA-PEs. Furthermore, co-incubation of cells with di-AA-PE and 15LOX produced PUFA-PE peroxidation and induced ferroptotic death. The decreased contents of di-PUFA-PEs in ACSL4 KO A375 cells was associated with lower levels of di-PUFA-PE peroxidation and enhanced resistance to ferroptosis. Thus, di-PUFA-PE species are newly identified phospholipid peroxidation substrates and regulators of ferroptosis, representing a promising therapeutic target for many diseases related to ferroptotic death.

Phospholipase iPLA2ß averts ferroptosis by eliminating a redox lipid death signal.

Ferroptosis, triggered by discoordination of iron, thiols and lipids, leads to the accumulation of 15-hydroperoxy (Hp)-arachidonoyl-phosphatidylethanolamine (15-HpETE-PE), generated by complexes of 15-lipoxygenase (15-LOX) and a scaffold protein, phosphatidylethanolamine (PE)-binding protein (PEBP)1. As the Ca2+-independent phospholipase A2ß (iPLA2ß, PLA2G6 or PNPLA9 gene) can preferentially hydrolyze peroxidized phospholipids, it may eliminate the ferroptotic 15-HpETE-PE death signal. Here, we demonstrate that by hydrolyzing 15-HpETE-PE, iPLA2ß averts ferroptosis, whereas its genetic or pharmacological inactivation sensitizes cells to ferroptosis. Given that PLA2G6 mutations relate to neurodegeneration, we examined fibroblasts from a patient with a Parkinson's disease (PD)-associated mutation (fPDR747W) and found selectively decreased 15-HpETE-PE-hydrolyzing activity, 15-HpETE-PE accumulation and elevated sensitivity to ferroptosis. CRISPR-Cas9-engineered Pnpla9R748W/R748W mice exhibited progressive parkinsonian motor deficits and 15-HpETE-PE accumulation. Elevated 15-HpETE-PE levels were also detected in midbrains of rotenone-infused parkinsonian rats and α-synuclein-mutant SncaA53T mice, with decreased iPLA2ß expression and a PD-relevant phenotype. Thus, iPLA2ß is a new ferroptosis regulator, and its mutations may be implicated in PD pathogenesis.

PEBP1 acts as a rheostat between prosurvival autophagy and ferroptotic death in asthmatic epithelial cells.

Temporally harmonized elimination of damaged or unnecessary organelles and cells is a prerequisite of health. Under Type 2 inflammatory conditions, human airway epithelial cells (HAECs) generate proferroptotic hydroperoxy-arachidonoyl-phosphatidylethanolamines (HpETE-PEs) as proximate death signals. Production of 15-HpETE-PE depends on activation of 15-lipoxygenase-1 (15LO1) in complex with PE-binding protein-1 (PEBP1). We hypothesized that cellular membrane damage induced by these proferroptotic phospholipids triggers compensatory prosurvival pathways, and in particular autophagic pathways, to prevent cell elimination through programmed death. We discovered that PEBP1 is pivotal to driving dynamic interactions with both proferroptotic 15LO1 and the autophagic protein microtubule-associated light chain-3 (LC3). Further, the 15LO1-PEBP1-generated ferroptotic phospholipid, 15-HpETE-PE, promoted LC3-I lipidation to stimulate autophagy. This concurrent activation of autophagy protects cells from ferroptotic death and release of mitochondrial DNA. Similar findings are observed in Type 2 Hi asthma, where high levels of both 15LO1-PEBP1 and LC3-II are seen in HAECs, in association with low bronchoalveolar lavage fluid mitochondrial DNA and more severe disease. The concomitant activation of ferroptosis and autophagy by 15LO1-PEBP1 complexes and their hydroperoxy-phospholipids reveals a pathobiologic pathway relevant to asthma and amenable to therapeutic targeting.

A novel XPA splice-site mutation identified in a 4-year-old Filipino girl with xeroderma pigmentosum.

We herein report a case of a 4-year-old Filipino girl initially seen through online consultation from a general physician. She was born to a 22-year-old primigravid mother, with no birth complications nor a history of consanguinity in the family. During the 1st month of life, she developed hyperpigmented macules over the face, neck, upper back, and limbs, which were exacerbated by sun exposure. At 2 years old, she developed a solitary erythematous papule on the nasal area, which gradually enlarged within one year and developed into an exophytic ulcerating tumor extending to the right supra-alar crease. Xeroderma pigmentosum and squamous cell carcinoma were confirmed by whole-exome sequencing and skin biopsy, respectively.

Redox lipid reprogramming commands susceptibility of macrophages and microglia to ferroptotic death.

Ferroptotic death is the penalty for losing control over three processes-iron metabolism, lipid peroxidation and thiol regulation-that are common in the pro-inflammatory environment where professional phagocytes fulfill their functions and yet survive. We hypothesized that redox reprogramming of 15-lipoxygenase (15-LOX) during the generation of pro-ferroptotic signal 15-hydroperoxy-eicosa-tetra-enoyl-phosphatidylethanolamine (15-HpETE-PE) modulates ferroptotic endurance. Here, we have discovered that inducible nitric oxide synthase (iNOS)/NO•-enrichment of activated M1 (but not alternatively activated M2) macrophages/microglia modulates susceptibility to ferroptosis. Genetic or pharmacologic depletion/inactivation of iNOS confers sensitivity on M1 cells, whereas NO• donors empower resistance of M2 cells to ferroptosis. In vivo, M1 phagocytes, in comparison to M2 phagocytes, exert higher resistance to pharmacologically induced ferroptosis. This resistance is diminished in iNOS-deficient cells in the pro-inflammatory conditions of brain trauma or the tumour microenvironment. The nitroxygenation of eicosatetraenoyl (ETE)-PE intermediates and oxidatively truncated species by NO• donors and/or suppression of NO• production by iNOS inhibitors represent a novel redox mechanism of regulation of ferroptosis in pro-inflammatory conditions.

Autodeubiquitination protects the tumor suppressor BAP1 from cytoplasmic sequestration mediated by the atypical ubiquitin ligase UBE2O.

The tumor suppressor BAP1 interacts with chromatin-associated proteins and regulates cell proliferation, but its mechanism of action and regulation remain poorly defined. We show that the ubiquitin-conjugating enzyme UBE2O multi-monoubiquitinates the nuclear localization signal of BAP1, thereby inducing its cytoplasmic sequestration. This activity is counteracted by BAP1 autodeubiquitination through intramolecular interactions. Significantly, we identified cancer-derived BAP1 mutations that abrogate autodeubiquitination and promote its cytoplasmic retention, indicating that BAP1 autodeubiquitination ensures tumor suppression. The antagonistic relationship between UBE2O and BAP1 is also observed during adipogenesis, whereby UBE2O promotes differentiation and cytoplasmic localization of BAP1. Finally, we established a putative targeting consensus sequence of UBE2O and identified numerous chromatin remodeling factors as potential targets, several of which tested positive for UBE2O-mediated ubiquitination. Thus, UBE2O defines an atypical ubiquitin-signaling pathway that coordinates the function of BAP1 and establishes a paradigm for regulation of nuclear trafficking of chromatin-associated proteins.

Partially Covered Versus Uncovered Self-Expandable Metal Stents: Coating Nor Diameter Affect Clinical Outcomes.

INTRODUCTION: Jaundice is a common initial presentation of malignant biliary stricture. In patients with life expectancies that are greater than 3 months, self-expanding metal stents (SEMS) offer a larger diameter stent with longer patency and fewer complications compared to plastic stents. There have been conflicting results in the published literature as to efficacy and safety between the various SEMS types and diameters. We compared stent coating (PCSEMS vs USEMS) and diameter on clinical outcomes regarding management of malignant biliary obstruction. METHODS: A retrospective cohort study was conducted using a database of consecutive patients who underwent an ERCP with biliary SEMS placement (only 8 and 10 mm) between 2009 and 2017. RESULTS: In total, 278 patients who had SEMS at ERCP for malignant biliary obstruction were included (213 PCSEMS vs 65 USEMS). The groups were demographically evenly matched. Clinical success rates and patency duration were not statistically significant between PCSEMS and USEMS (98.1% vs 95.5%, P = 0.36, and 302.5 vs 225.5 days, P = 0.72, respectively). Adverse event rates were similar between both PCSEMS and USEMS with regard to overall adverse events. Stent diameter did not have an impact on overall clinical success (98.9% vs 95.3%, P = 0.11) or patency duration (239 days vs 336 days, P = 0.51). CONCLUSIONS: Our comparison of PCSEMS versus USEMS and 8 mm versus 10 mm showed no difference in clinical efficacy or adverse events between the two SEMS coatings and diameter, illustrating that coating and size do not matter in regard to stent choice, despite prior suggestive data.

Empowerment of 15-Lipoxygenase Catalytic Competence in Selective Oxidation of Membrane ETE-PE to Ferroptotic Death Signals, HpETE-PE.

sn2-15-Hydroperoxy-eicasotetraenoyl-phosphatidylethanolamines ( sn2-15-HpETE-PE) generated by mammalian 15-lipoxygenase/phosphatidylethanolamine binding protein-1 (15-LO/PEBP1) complex is a death signal in a recently identified type of programmed cell demise, ferroptosis. How the enzymatic complex selects sn2-ETE-PE as the substrate among 1 of ∼100 total oxidizable membrane PUFA phospholipids is a central, yet unresolved question. To unearth the highly selective and specific mechanisms of catalytic competence, we used a combination of redox lipidomics, mutational and computational structural analysis to show they stem from (i) reactivity toward readily accessible hexagonally organized membrane sn2-ETE-PEs, (ii) relative preponderance of sn2-ETE-PE species vs other sn2-ETE-PLs, and (iii) allosteric modification of the enzyme in the complex with PEBP1. This emphasizes the role of enzymatic vs random stochastic free radical reactions in ferroptotic death signaling.

Antineutrino Charged-Current Reactions on Hydrocarbon with Low Momentum Transfer.

We report on multinucleon effects in low momentum transfer (<0.8 GeV/c) antineutrino interactions on plastic (CH) scintillator. These data are from the 2010-2011 antineutrino phase of the MINERvA experiment at Fermilab. The hadronic energy spectrum of this inclusive sample is well described when a screening effect at a low energy transfer and a two-nucleon knockout process are added to a relativistic Fermi gas model of quasielastic, Δ resonance, and higher resonance processes. In this analysis, model elements introduced to describe previously published neutrino results have quantitatively similar benefits for this antineutrino sample. We present the results as a double-differential cross section to accelerate the investigation of alternate models for antineutrino scattering off nuclei.

Arginase and C-reactive protein as potential serum-based biomarker of head and neck squamous cell carcinoma patients of north east India.

Head and neck squamous cell carcinoma (HNSCC) diagnosis involves histopathological investigations with intervention procedures. Widely accepted biochemical panels for HNSCC detection is not available yet. We tried to find out the effectiveness of the serum-based biochemical markers for their prognostic significance in HNSCC. We collected fresh blood samples of 80 HNSCC patients and 100 healthy subjects. Samples were analyzed for absolute levels of arginase (ARG), ornithine aminotransferase (OAT), catalase (CAT), lactate dehydrogenase (LDH), amylase (AMY) activity, and C-reactive protein (CRP). Receiver-operator characteristic curves and Fagan's nomograms were generated. Out of six parameters studied, four (OAT, CAT, LDH, and AMY) did not show biologically significant differences to be used as biomarkers. Significant elevation in serum ARG and CRP levels were observed in HNSCC. The individual estimation of ARG and CRP showed lower specificity, but their combination improved the specificity level to 95%. Our results suggest that serum ARG and CRP together can efficiently diagnose HNSCC.

Association between human leukocyte antigen-DR and demylinating Guillain-Barre syndrome.

OBJECTIVE: To find an association between human leukocyte antigen (HLA) class II DRB1, DRB3, DRB4, and DRB5 alleles frequencies in a sample of Iraqi patients with Guillain-Barre syndrome (GBS) and compare with a healthy control group. METHODS: We performed a cross-sectional study consisting of 30 Iraqi Arab patients with GBS attending the Neurological Department in the Neuroscience Hospital, Baghdad, Iraq between September 2012 and June 2013. The control group comprised 42 apparently healthy volunteers. Human leukocyte antigen genotyping for HLA DRB1, DRB3, DRB4, and DRB5 was performed using the polymerase chain reaction-sequence-specific primers method. The allele frequencies were compared across both groups. Major histocompatibility complex (MHC)-class II HLA-DR genotyping and serotyping were performed by software analysis. RESULTS: We found increased frequencies of HLA genotype DRB1*03:01 (p=0.0009), DRB1*07:01 (p=0.0015), and DRB4*01:01 (p<0.0001) in patients with GBS compared with healthy controls. The HLA DR6 was increased in the control group (p<0.0001). CONCLUSION: Our results suggest an association between HLA-DRB1*03:01, DRB1*07:01, DRB4*01:01, and HLA DR3, DR7 and a susceptibility to GBS.

Molecular identification of Entamoeba spp. in humans and cattle in Baghdad, Iraq.

Background and Aim: A total of 10% of the global population succumbs to amoebiasis yearly, equating to 50,000-100,000 recorded fatalities. It is closely associated with contaminated food and water supplies due to human feces. The disease's pathophysiology remains a subject of ongoing debate among experts. Some experts attribute the role of the host's conditions, parasite species and strain, and infection intensity in eliciting clinical symptoms. The aim of this study was to perform molecular identification of Entamoeba species isolated from humans and cattle. Materials and Methods: Stool samples from three hundred patients and one hundred cattle were collected from different regions, age groups, and sexes in Baghdad for microscopic examination. One hundred randomly chosen patient and cattle stool samples underwent microscopic examination and conventional polymerase chain reaction (PCR) targeting the 18S rRNA gene. Phylogenetic tree analyses were performed for Entamoeba species identification. Results: The infection rate in humans differed significantly (p < 0.05) between age groups and genders, totaling 38%. The infection rate in cattle, determined by conventional PCR, differed significantly (p < 0.05) between age groups and genders, amounting to 58%. Ten PCR products with positive results were sequenced and deposited in GenBank database. Sequence analysis detected that Eight sequences belong to E. histolytica (OM268853.1, OM268854.1, OM268855.1, OM268857.1, OM268858.1, OM268860.1, OM268861.1, and OM268862.1) and two sequences belong to E. dispar (OM268856.1 and OM268859.1) in humans, while 10 sequences (ON724165.1 to ON724174.1) belongs to E. histolytica in cattle. Conclusion: The increased susceptibility of cattle to E. histolytica suggests a considerable role in human infection and substantial public health risks. Further research should be conducted on the many virulence factors such as HM1:IMSS strain, cysteinprotease (Cp1), Gal/lectin, etc. of E. histolytica and E. dispar.

Enhancing orthodontic treatment control with fish scale-derived hydroxyapatite nanoparticles: Insights from an animal model study.

Objectives: This study investigates the impact of injected fish-scale-derived hydroxyapatite nanoparticles (FsHA-NPs) on orthodontic tooth movement (OTM) and the width of the periodontal ligament (PDL) space. Materials and Methods: Twenty-six Wistar rats underwent mesial orthodontic traction with a force of 50 g for 21 days. Following the application of the orthodontic appliance, the rats were randomly divided into two groups: a control group, which received a 0.3 µg saline injection, and the experimental FsHA group, which received 100 mg/0.3 ml of FsHA-NPs after thorough characterisation. Injections were administered immediately after appliance application and repeated at 7 and 14 days. Statistical analysis was conducted with a significance level of P ≤ 0.05. Result: The experimental group exhibited a significant reduction in OTM at 7-, 14-, and 21-day post-force application. Additionally, a reduction in PDL width was observed in the mesiocervical and disto-apical regions of the mesial and distal roots of the first molar. Conclusion: FsHA-NPs derived from biowaste fish scales exhibit promising potential as biomaterials for enhancing control over OTM. This study underscores the viability, accessibility, and safety of FsHA-NPs as a locally injectable material for orthodontic applications.

PHLDA2-mediated phosphatidic acid peroxidation triggers a distinct ferroptotic response during tumor suppression.

Although the role of ferroptosis in killing tumor cells is well established, recent studies indicate that ferroptosis inducers also sabotage anti-tumor immunity by killing neutrophils and thus unexpectedly stimulate tumor growth, raising a serious issue about whether ferroptosis effectively suppresses tumor development in vivo. Through genome-wide CRISPR-Cas9 screenings, we discover a pleckstrin homology-like domain family A member 2 (PHLDA2)-mediated ferroptosis pathway that is neither ACSL4-dependent nor requires common ferroptosis inducers. PHLDA2-mediated ferroptosis acts through the peroxidation of phosphatidic acid (PA) upon high levels of reactive oxygen species (ROS). ROS-induced ferroptosis is critical for tumor growth in the absence of common ferroptosis inducers; strikingly, loss of PHLDA2 abrogates ROS-induced ferroptosis and promotes tumor growth but has no obvious effect in normal tissues in both immunodeficient and immunocompetent mouse tumor models. These data demonstrate that PHLDA2-mediated PA peroxidation triggers a distinct ferroptosis response critical for tumor suppression and reveal that PHLDA2-mediated ferroptosis occurs naturally in vivo without any treatment from ferroptosis inducers.

Prevalence and molecular characterization of Giardia intestinalis isolated from children and calves in Babylon province, Iraq.

Background and Aim: Giardia intestinalis is one of the most prevalent intestinal parasites in humans and animals, and children in close contact with livestock are particularly at risk of infection. This study aimed to detect assemblages of G. intestinalis and determine the origin of zoonotic transmission of Giardia in children and calves in different parts of Babylon province, Iraq. Materials and Methods: One hundred stool samples from children (68 boys and 32 girls) and 100 fecal samples from calves (46 males and 54 females) of different ages were randomly collected. Molecular techniques were used to estimate the prevalence of G. intestinalis in children and calves. A nested polymerase chain reaction (PCR) was performed by targeting the triose phosphate isomerase gene in the samples to detect G. intestinalis assemblages. Results: The overall rates of infection with G. intestinalis in children and calves were 21% and 34%, respectively, using the conventional microscopic method. The results illustrated that 61.90% (13/21) and 38.09% (8/21) of positive samples from children were allocated to assemblages A and B, respectively (p > 0.05). In calves, assemblages A and B were detecte in 82.35% (28/34) and 17.64% (6/34) of positive samples from calves, respectively (p ≤ 0.001). Ten PCR products were sequenced and submitted to the GenBank database. Phylogenetic analysis detected five human sequences each belonging to G. intestinalis assemblages A (OM850335-OM850339) and B (OM850340-OM850344). Similarly, five calf sequences each belonged to G. intestinalis assemblages A (ON75756-ON757660) and B (ON757661-ON757665). Conclusion: The detection of large numbers of G. intestinalis assemblage A in both humans and cattle indicated that cattle could be a main source of zoonotic G. intestinalis infection in children in Babylon province, Iraq.

Correlation of amyloid and ameloblast-associated proteins to odontogenic cysts and tumors: A cross-sectional study.

Background and Aims: Odontogenic cysts and tumors often form hard and soft structures that resemble odontogenesis. It is well known that amyloid is produced in Pindborg tumors; however, it is still debatable whether it is also formed in other odontogenic tumors and cysts. This study aimed to detect the presence of amyloid in different odontogenic cysts and tumors in correlation to matrix proteins secreted during enamel formation; namely amelogenin and odontogenic ameloblast-associated protein. Methods: This study included formalin fixed paraffin embedded tissue blocks of 106 different types of odontogenic cysts and tumors. Congo red and thioflavin T were performed to confirm the presence of amyloid; immunohistochemistry was used to detect amelogenin and odontogenic ameloblast-associated protein. Results: Amyloid was detected in pindborg tumors (conventional), adenomatoid odontogenic tumors, odontogenic fibroma (Amyloid variant), follicular solid and unicystic ameloblastomas, radicular cysts, dentigerous cysts, dentinogenic ghost cell odontogenic tumor, ameloblastic fibroma, calcifying odontogenic cyst, and primordial Odontogenic tumor. Amelogenin was detected in 95.3% of the cases, while odontogenic ameloblast-associated protein was detected in 93.4% of the cases. The association between odontogenic ameloblast-associated protein and amyloid was highly significant at p < 0.01. However, there was no significant relationship between amelogenin and amyloid p > 0.05. Conclusion: Although pindborg tumor is the bonafide example of amyloid deposition in odontogenic tumors, this study concluded that amyloid may be deposited in traces to massive amounts in various odontogenic cysts and tumors, and it is significantly linked to odontogenic ameloblast-associated protein but not amelogenin matrix protein, since all amyloid cases were odontogenic ameloblast associated protein positive.