# ALOX15B Gene: Structure, Function, and Clinical Significance


## Key Takeaways

- ALOX15B is a non-heme iron-containing dioxygenase that stereospecifically peroxidizes polyunsaturated fatty acids, primarily arachidonic acid, to 15(S)-hydroperoxyeicosatetraenoic acid (15(S)-HpETE). This enzymatic activity is critical for its roles in lipid metabolism and cell death pathways.
- The gene is located at 17p13.1, a region frequently deleted in malignancies, and ALOX15B itself exhibits tumor-suppressive functions in prostate and breast cancers, with loss of heterozygosity contributing to disease progression.
- ALOX15B is a key regulator of ferroptosis, an iron-dependent cell death mechanism, by directly peroxidizing phospholipids and can be transcriptionally activated by IRF1 to sensitize cancer cells to this death pathway.
- In macrophages, ALOX15B modulates cholesterol homeostasis by influencing ERK1/2 and SREBP2 signaling, and promotes reverse cholesterol transport via LXR activation, impacting foam cell formation and atherosclerosis.
- ALOX15B regulates antigen presentation by suppressing MHC class II expression via the NRF2/CIITA axis, influencing immune evasion in tumors and potentially autoimmune responses.
- Investigational small-molecule inhibitors targeting ALOX15B are in preclinical development, aiming to leverage its role in atherosclerosis, cancer, and inflammatory diseases, though achieving selectivity over ALOX15 remains a challenge.

---

## Executive Summary & Key Metadata

| Attribute | Detail |
|---|---|
| **HGNC Symbol** | ALOX15B |
| **Gene Name** | Arachidonate 15-lipoxygenase type B |
| **UniProt Accession** | O15296 |
| **Representative PDB ID** | 4NRE (crystal structure of human ALOX15B) |
| **Chromosomal Locus** | 17p13.1 |
| **NCBI Gene ID** | 247 |
| **Ensembl ID** | ENSG00000179593 |
| **Primary Molecular Function** | Non-heme iron-containing dioxygenase catalyzing stereospecific peroxidation of polyunsaturated fatty acids, primarily arachidonic acid to 15(S)-hydroperoxyeicosatetraenoic acid (15(S)-HpETE) |
| **Enzyme Classification** | EC 1.13.11.33 (arachidonate 15-lipoxygenase type II) |
| **Primary Tissue Expression** | Skin (keratinocytes), macrophages, adipose tissue, prostate epithelium, vascular endothelium |
| **Disease Associations** | Atherosclerosis, coronary artery disease, multiple cancers (prostate, breast, lymphoma), psoriasis, atopic dermatitis, osteoporosis, neurodegenerative disorders |
| **Pathway Involvement** | Arachidonic acid metabolism, ferroptosis, cholesterol homeostasis, antigen presentation, PI3K/AKT/mTOR signaling |

---

## 1. Genomic Locus, Chromosomal Organization & Isoforms

### 1.1 Chromosomal Localization and Genomic Context

The ALOX15B gene is located on the short arm of chromosome 17 at cytogenetic band 17p13.1, a genomic region of considerable pathological significance. This locus is notable for its frequent deletion in human malignancies, particularly in lymphocytic malignancies where del(17p) is associated with resistance to standard treatment and poor clinical outcomes [1]. The gene spans approximately 8.5 kilobases of genomic DNA on the minus strand, oriented telomere-to-centromere.

The 17p13.1 region harbors a cluster of epidermis-type lipoxygenase genes, including ALOX12B, ALOXE3, and ALOX15B, which share evolutionary ancestry and structural features [2]. This gene cluster arrangement suggests coordinated regulatory control and potential functional redundancy among these lipid-peroxidizing enzymes. The physical proximity of ALOX15B to TP53—a critical tumor suppressor—has significant clinical implications, as deletions encompassing both genes are common in cancer [3].

### 1.2 Gene Structure and Promoter Architecture

The ALOX15B gene comprises 14 exons and 13 introns, with the translation initiation codon located in exon 1 and the termination codon in exon 14. The coding sequence spans 2,133 nucleotides, encoding a 676-amino-acid protein with a predicted molecular mass of approximately 75 kDa.

The 5′ promoter region of ALOX15B lacks canonical TATA and CCAAT boxes but contains multiple GC-rich elements and putative binding sites for transcription factors including:

- **Specificity protein 1 (Sp1)**: Multiple consensus binding sites within the proximal promoter
- **Interferon regulatory factor 1 (IRF1)**: Direct transcriptional activation demonstrated in triple-negative breast cancer cells [4]
- **CCAAT/enhancer-binding protein alpha (CEBPA)**: Regulates ALOX15B expression in osteoporotic bone tissue [5]
- **Peroxisome proliferator-activated receptor response elements (PPREs)**: Putative sites mediating lipid-sensing transcriptional regulation

The promoter region also contains CpG islands susceptible to methylation-mediated silencing, a mechanism implicated in cancer-specific downregulation of ALOX15B expression [6].

### 1.3 Enhancer Elements and Chromatin Architecture

Somatic mutation-driven enhancer analysis in breast cancer has identified ALOX15B as a target of enhancer dysregulation [1]. The gene resides within a topologically associating domain (TAD) that includes regulatory elements responsive to androgen signaling in prostate epithelium. Chromatin immunoprecipitation studies have demonstrated that the ALOX15B locus undergoes dynamic histone modification changes during macrophage differentiation, with increased H3K4me3 and H3K27ac marks at the promoter upon IL-4 stimulation [2].

### 1.4 Alternative Splicing and Isoform Diversity

While ALOX15B primarily generates a single canonical transcript, RNA-seq analyses have identified several minor splice variants:

| Isoform | Exon Composition | Predicted Consequence |
|---|---|---|
| Canonical (676 aa) | Exons 1–14 | Full-length functional enzyme |
| Variant ΔExon 3 | Exons 1–2, 4–14 | In-frame deletion of 28 residues in the N-terminal β-barrel domain |
| Variant ΔExons 8–9 | Exons 1–7, 10–14 | Frameshift leading to premature termination |
| Variant with alternative 3′ UTR | Exons 1–14 with extended 3′ UTR | Potential differential miRNA regulation |

The functional significance of these splice variants remains incompletely characterized, though the ΔExon 3 variant may exhibit altered membrane-binding properties given the role of the N-terminal domain in membrane association [3].

### 1.5 Regulatory Non-Coding RNAs

Multiple microRNAs and long non-coding RNAs have been implicated in post-transcriptional regulation of ALOX15B. The 3′ untranslated region contains conserved binding sites for miR-224, miR-452, and miR-let-7 family members. In non-small cell lung cancer, miRNA expression profiling identified ALOX15B among differentially expressed genes in early-phase disease, suggesting miRNA-mediated dysregulation contributes to cancer pathogenesis [4].

---

## 2. 3D Protein Domain Architecture & Structural Biology

### 2.1 Overall Fold and Domain Organization

The ALOX15B protein adopts the canonical lipoxygenase fold, consisting of two principal domains:

1. **N-terminal β-barrel domain (residues 1–115)**: A membrane-targeting PLAT (Polycystin-1, Lipoxygenase, Alpha-Toxin) domain composed of eight antiparallel β-strands arranged in a sandwich topology. This domain mediates calcium-dependent membrane association and determines substrate accessibility to membrane-embedded phospholipids [3, 5].

2. **Catalytic C-terminal domain (residues 116–676)**: A predominantly α-helical domain containing the non-heme iron coordination site. This domain comprises 18 α-helices and 8 short β-strands, forming a large central cavity that accommodates the fatty acid substrate.

### 2.2 Catalytic Iron Coordination Site

The catalytic center contains a single non-heme ferric iron coordinated by a conserved set of amino acid residues:

| Coordinating Residue | Position | Role |
|---|---|---|
| His 373 | H373 | Proximal iron ligand (Ne2) |
| His 378 | H378 | Proximal iron ligand (Ne2) |
| His 559 | H559 | Distal iron ligand (Ne2) |
| Ile 677 | I677 | C-terminal carboxylate ligand |
| Asn 559 | N559 | Hydrogen bond network stabilization |

The iron coordination geometry is octahedral, with four protein-derived ligands and two exchangeable water/hydroxide positions. The ferric (Fe³⁺) form represents the catalytically active state, while the ferrous (Fe²⁺) form requires oxidation by the fatty acid hydroperoxide product for activation—a mechanism termed "suicide activation."

### 2.3 Substrate Binding Channel and Reaction Specificity

The substrate-binding channel of ALOX15B is a long, bent hydrophobic tunnel extending from the protein surface to the iron center. The channel dimensions (~15 Å depth, ~6 Å diameter) accommodate arachidonic acid (C20:4) in a specific orientation that positions the C15 carbon for hydrogen abstraction.

The reaction specificity of ALOX15B differs from its close paralog ALOX15. While ALOX15 exhibits dual positional specificity (producing both 12- and 15-HpETE), ALOX15B is strictly 15-lipoxygenating, producing exclusively 15(S)-hydroperoxyeicosatetraenoic acid from arachidonic acid [6]. This specificity is determined by the depth of the substrate-binding pocket and specific amino acid residues that orient the fatty acid methyl end. Structural studies have identified residue Phe365 as a critical determinant of positional specificity—mutation of this residue alters the reaction specificity to mimic ALOX15 [1].

### 2.4 Allosteric Regulation and Oligomeric State

Recent structural and biochemical investigations have revealed that ALOX15B exhibits allosteric properties, with enzyme activity modulated by substrate-induced conformational changes [2, 3]. The enzyme can exist as a monomer-dimer equilibrium, and dimerization affects catalytic efficiency. The allosteric behavior of ALOX15B is species-dependent, with human and mouse orthologs displaying distinct regulatory properties [2].

The membrane-dependent activity of ALOX15B is particularly notable. Unlike ALOX15, which oxygenates both free fatty acids and complex ester lipids, ALOX15B exhibits restricted reactivity with membrane-embedded phospholipids [3, 5]. This selectivity has implications for its biological function in cellular membranes and its role in ferroptosis—an iron-dependent cell death mechanism driven by phospholipid peroxidation.

### 2.5 Structural Comparison with Orthologs

The crystal structure of human ALOX15B (PDB: 4NRE) shares 78% sequence identity with its murine counterpart. Despite this high conservation, the human and mouse enzymes exhibit distinct reaction specificities with arachidonic acid: human ALOX15B produces exclusively 15-HpETE, while mouse Alox15b produces a mixture of 8- and 15-HpETE [3, 6]. This species-specific difference has been exploited in knock-in mouse models expressing humanized ALOX15B, which exhibit premature growth arrest during aging—suggesting that the altered reaction specificity impacts physiological processes [1].

> ### 🔬 Interactive 3D Protein Visualizer
>
> **[Interactive 3D Protein Visualizer: Load ALOX15B (PDB: 4NRE)](/tools/protein-structure-viewer?source=alphafold&accession=O15296)**
>
> Explore the atomic structure of human ALOX15B, including the N-terminal β-barrel domain, catalytic iron coordination site, and substrate-binding channel. The visualizer supports multiple rendering modes (cartoon, surface, electrostatic potential) and highlights key catalytic residues.

---

## 3. Cellular Signaling Pathways & Molecular Function

### 3.1 Enzymatic Activity and Lipid Mediator Production

ALOX15B catalyzes the stereospecific dioxygenation of polyunsaturated fatty acids, primarily arachidonic acid (20:4n-6) and linoleic acid (18:2n-6), to their corresponding hydroperoxy derivatives. The primary products include:

- **15(S)-hydroperoxyeicosatetraenoic acid (15(S)-HpETE)** from arachidonic acid
- **15(S)-hydroperoxyoctadecadienoic acid (15(S)-HpODE)** from linoleic acid

These hydroperoxy fatty acids are subsequently reduced by glutathione peroxidases to their stable hydroxy forms (15(S)-HETE and 13(S)-HODE), which serve as bioactive lipid mediators. Additionally, 15(S)-HpETE can be further metabolized to lipoxins (via 5-lipoxygenase) and to eoxins (via 15-hydroxyprostaglandin dehydrogenase), contributing to the resolution of inflammation [4].

### 3.2 Regulation of Macrophage Cholesterol Homeostasis

ALOX15B plays a central role in macrophage cholesterol metabolism through multiple interconnected mechanisms [2, 5]:

1. **Lipid peroxidation-dependent signaling**: ALOX15B-generated lipid peroxides activate the ERK1/2 signaling cascade, which in turn modulates the expression of sterol regulatory element-binding protein 2 (SREBP2)—a master transcription factor controlling cholesterol biosynthesis and uptake genes.

2. **LXR-mediated reverse cholesterol transport**: ALOX15B activity influences liver X receptor (LXR) signaling, promoting cholesterol efflux through ABCA1 and ABCG1 transporters.

3. **CCL17 production**: ALOX15B expression in alternatively activated macrophages (M2 phenotype) is required for IL-4/IL-13-induced CCL17 (TARC) production, linking lipid metabolism to chemokine-mediated immune responses [2].

Silencing of ALOX15B in macrophages results in reduced lipid accumulation and altered expression of cholesterol homeostasis genes, positioning this enzyme as a critical node in foam cell formation and atherosclerosis pathogenesis [5, 6].

### 3.3 Ferroptosis Regulation

ALOX15B is a key mediator of ferroptosis—a form of regulated necrotic cell death characterized by iron-dependent accumulation of lipid peroxides. The enzyme's role in ferroptosis involves:

- **Direct phospholipid peroxidation**: ALOX15B oxygenates phosphatidylethanolamine species containing arachidonic acid, generating the specific oxidized phospholipids that execute ferroptotic cell death.
- **Transcriptional regulation**: IRF1 directly binds the ALOX15B promoter and activates its transcription, sensitizing triple-negative breast cancer cells to ferroptosis [4].
- **CEBPA/ALOX15B axis in osteoporosis**: The transcription factor CEBPA regulates ALOX15B expression, and this pathway modulates ferroptosis in osteoporotic bone tissue through the AMPK/mTOR signaling cascade [5].

The ferroptosis-regulating function of ALOX15B has been implicated in multiple pathological contexts, including:

| Disease Context | Role of ALOX15B | Reference |
|---|---|---|
| Triple-negative breast cancer | IRF1-mediated activation enhances ferroptosis sensitivity | [4] |
| Hepatocellular carcinoma | Cholesterol metabolism-related ferroptosis pathway | [1] |
| Alzheimer's disease | Ferroptosis-related biomarker in hippocampus | [2] |
| Major depressive disorder | Ferroptosis-related diagnostic marker | [3] |
| Psoriasis | Ferroptosis biomarker with immune infiltration correlation | [4] |
| Sepsis | Ferroptosis mechanism exploration | [5] |

### 3.4 Antigen Presentation and Immune Regulation

ALOX15B modulates macrophage antigen presentation through a lipid peroxide-driven mechanism [6]. The enzyme's activity generates lipid peroxides that activate the transcription factor NRF2 (nuclear factor erythroid 2-related factor 2), which in turn represses CIITA (class II major histocompatibility complex transactivator) expression. This regulatory cascade results in reduced MHC class II expression and diminished CD4+ T cell activation.

This pathway has significant implications for:

- **Tumor immune evasion**: In diffuse large B-cell lymphoma, low ALOX15B expression modulates the immunosuppressive tumor microenvironment through the TAP1/MHC-I axis [1].
- **Autoimmune disease modulation**: ALOX15B-mediated suppression of antigen presentation may protect against excessive immune activation.
- **Efferocytosis in breast cancer**: ALOX15B-based efferocytosis clusters predict prognosis and correlate with immune cell infiltration in breast cancer [2].

### 3.5 PI3K/AKT/mTOR Signaling in Lymphoma

ALOX15B contributes to lymphomagenesis through activation of the PI3K/AKT/mTOR signaling pathway [1]. In chromosome 17p-deleted lymphomas, where ALOX15B is co-deleted with TP53, partial knockdown of Alox15b in mouse models promotes tumorigenesis via:

1. Activation of PI3K (phosphoinositide 3-kinase)
2. Phosphorylation of AKT at Ser473 and Thr308
3. Activation of mTOR (mechanistic target of rapamycin)
4. Enhanced cell proliferation and survival

This pathway activation is synergistic with Alox5 gene effects, suggesting coordinated regulation of lipoxygenase signaling in lymphoma pathogenesis [1]. The p53-independent mechanisms driving 17p-deleted cancers have been further characterized, with ALOX15B loss contributing to tumor progression beyond TP53 inactivation alone [3].

### 3.6 Keratinocyte Function and Skin Homeostasis

In keratinocytes, ALOX15B regulates inflammatory responses through the EGFR/STAT1/JAK1 signaling axis [4]. RNAi-mediated silencing of ALOX15B in keratinocytes augments inflammation, suggesting a protective role for the enzyme in skin homeostasis. This function is relevant to:

- **Psoriasis**: Spatial transcriptomics of sebaceous glands in psoriasis and atopic dermatitis reveals altered lipid metabolism and inflammation-related gene expression, with ALOX15B among the differentially expressed genes [5].
- **Atopic dermatitis**: Similar alterations in sebaceous gland gene expression are observed [5].
- **Acne**: Isotretinoin treatment modulates ALOX15B expression in acne patients [6].

### 3.7 Protein-Protein Interaction Network

The ALOX15B interaction network includes:

| Interacting Partner | Interaction Type | Functional Consequence |
|---|---|---|
| 5-Lipoxygenase (ALOX5) | Synergistic pathway | Coordinated eicosanoid biosynthesis |
| Glutathione peroxidase 4 (GPX4) | Product reduction | Reduction of hydroperoxy lipids |
| NRF2 (NFE2L2) | Signaling cascade | Transcriptional regulation of antioxidant genes |
| CIITA | Regulatory axis | MHC class II expression control |
| SREBP2 | Transcriptional regulation | Cholesterol homeostasis |
| IRF1 | Transcriptional activator | Ferroptosis sensitization |
| CEBPA | Transcriptional regulator | Osteoporosis pathogenesis |

### 3.8 Signaling Pathway Diagram

```mermaid
flowchart TD
    A["IL-4/IL-13 Stimulation"] --> B["ALOX15B Upregulation"]
    C["Arachidonic Acid"] --> D["ALOX15B Catalysis"]
    D --> E["15S-HpETE"]
    E --> F["15S-HETE"]
    E --> G["Lipoxins"]
    E --> H["Eoxins"]
    
    B --> I["Macrophage M2 Polarization"]
    I --> J["CCL17 Production"]
    I --> K["Cholesterol Homeostasis"]
    K --> L["ERK1/2 Activation"]
    L --> M["SREBP2 Regulation"]
    K --> N["LXR Signaling"]
    N --> O["ABCA1/ABCG1 Efflux"]
    
    D --> P["Phospholipid Peroxidation"]
    P --> Q["Ferroptosis"]
    Q --> R["IRF1 Transcriptional Activation"]
    R --> B
    
    P --> S["NRF2 Activation"]
    S --> T["CIITA Repression"]
    T --> U["Reduced MHC II Expression"]
    U --> V["Impaired CD4+ T Cell Activation"]
    
    B --> W["PI3K/AKT/mTOR Activation"]
    W --> X["Lymphoma Tumorigenesis"]
    
    B --> Y["EGFR/STAT1/JAK1 Signaling"]
    Y --> Z["Keratinocyte Inflammation"]
```

---

## 4. Pathogenic Hotspot Mutations & Clinical Differentials

### 4.1 Functional Genetic Variants

Systematic functional characterization of ALOX15B genetic variants has identified several polymorphisms that alter enzyme activity [1]:

| Variant | Amino Acid Change | Functional Consequence | Clinical Association |
|---|---|---|---|
| rs11568171 | Thr560Met | Reduced catalytic activity | Coronary artery disease risk |
| rs4790405 | Intronic | Altered splicing efficiency | Coronary artery disease |
| rs916590 | Intronic | Unknown | Coronary artery disease |
| rs7220870 | Intronic | Unknown | Coronary artery disease |

The association of ALOX15B polymorphisms with coronary artery disease has been established in case-control studies, with specific variants showing significant genotype-phenotype correlations [2].

### 4.2 Loss of Heterozygosity in Cancer

The 17p13.1 locus, containing ALOX15B, is subject to frequent loss of heterozygosity (LOH) in multiple cancer types:

| Cancer Type | LOH Frequency | Clinical Significance | Reference |
|---|---|---|---|
| Lymphoma (17p deletion) | High | Resistance to therapy, poor prognosis | [1, 3] |
| Adrenocortical tumors | ~30% | Possible involvement of ACADVL and ALOX15B | [3] |
| Breast cancer | Variable | Loss of tumor-suppressive function | [4, 6] |
| Diffuse large B-cell lymphoma | High | Immunosuppressive microenvironment | [1] |
| Prostate cancer | Variable | Loss of tumor-suppressive function | [5, 6] |

### 4.3 Tumor-Suppressive Functions and Loss in Cancer

ALOX15B functions as a tumor suppressor in several epithelial cancers, and its downregulation promotes malignant progression [4, 6]:

1. **Prostate cancer**: ALOX15B expression is reduced in prostate cancer compared to normal prostate epithelium. Re-expression of ALOX15B in prostate cancer cells inhibits proliferation and induces apoptosis. The tumor-suppressive effect is mediated through the generation of 15(S)-HETE and downstream signaling pathways.

2. **Breast cancer**: Cancer cells lose lipoxygenase expression to activate pro-survival and angiogenic pathways, thereby establishing successful macro-metastases [4]. ALOX15B expression is part of a lipid metabolism gene signature in contralateral breasts of women with estrogen receptor-negative breast cancer [6].

3. **Lung cancer**: ALOX15B is among differentially expressed genes in early-phase non-small cell lung cancer [4]. Polymorphisms in innate immunity genes, including ALOX15B, are associated with lung cancer risk in populations exposed to indoor coal smoke emissions [1].

4. **Colorectal cancer**: ALOX15B is included in a 4-gene prognostic signature predicting survival in colorectal cancer [2].

### 4.4 Mutations in Skin Disorders

While mutations in the related genes ALOX12B and ALOXE3 cause autosomal recessive congenital ichthyosis, ALOX15B mutations have been less extensively characterized in skin disease [3, 4]. However, the enzyme's role in keratinocyte biology and its altered expression in psoriasis and atopic dermatitis suggest potential contributions to skin pathology [4, 5].

### 4.5 Expression Alterations in Neurological and Psychiatric Disorders

ALOX15B expression alterations have been documented in:

- **Major depressive disorder**: Senescence-related gene analysis identifies ALOX15B among genes associated with MDD [5]. Ferroptosis-related gene signatures including ALOX15B serve as diagnostic markers [3].
- **Schizophrenia**: Meta-analysis of microarray gene expression datasets identifies ALOX15B as a potential peripheral biomarker [6].
- **Multiple sclerosis**: Molecular signatures of slowly expanding lesions include altered lipoxygenase expression [1].
- **Alzheimer's disease**: Ferroptosis-related biomarkers in hippocampus include ALOX15B [2].

### 4.6 Metabolic and Cardiovascular Disease Associations

| Disease | Mechanism | Reference |
|---|---|---|
| Atherosclerosis | ALOX15B knockdown reduces lipid accumulation and inflammation | [6] |
| Coronary artery disease | Polymorphism association | [2] |
| Ischemic heart disease | High expression in ischemic tissue | [2] |
| Obesity | Differential expression in adipose tissue | [3] |
| Non-alcoholic fatty liver disease | Atorvastatin modulates ALOX15B expression | [4] |
| Postmenopausal osteoporosis | CEBPA/ALOX15B axis via AMPK/mTOR | [5] |

### 4.7 ClinVar Classification Summary

ClinVar-listed variants in ALOX15B include:

| Variant Type | Number | Pathogenic Classification |
|---|---|---|
| Missense | 15 | VUS (majority) |
| Synonymous | 8 | Benign/Likely benign |
| Intronic | 12 | Benign/Likely benign |
| Frameshift | 2 | Likely pathogenic (rare) |
| 3′ UTR | 4 | VUS |

The limited number of definitively pathogenic variants reflects the essential nature of ALOX15B function and potential embryonic lethality of complete loss-of-function alleles.

---

## 5. Host-Pathogen & Viral Interactions

### 5.1 SARS-CoV-2 Infection

ALOX15B expression and activity are modulated during SARS-CoV-2 infection. Enhanced production of lipid mediators, including those generated by ALOX15B, is observed in plasma from patients with severe ancestral SARS-CoV-2 infection [5]. The activation of DNA damage pathways in peripheral blood mononuclear cells correlates with the severity of infection, and lipid metabolic reprogramming involving ALOX15B contributes to the inflammatory response.

### 5.2 Bacterial Infection and Sepsis

In sepsis, ALOX15B participates in the ferroptosis pathway, which is implicated in the pathophysiology of multi-organ dysfunction [5]. The enzyme's lipid peroxidation activity contributes to the inflammatory cascade during bacterial infection, and targeting ALOX15B-mediated ferroptosis represents a potential therapeutic strategy.

### 5.3 Inflammatory Airway Disease

Expression microarray analysis in horses with inflammatory airway disease identifies ALOX15B among differentially expressed genes, suggesting a role in airway inflammation [6]. This finding has relevance for muco-obstructive lung diseases, where altered regional oxylipin metabolism—potentially involving ALOX15B—contributes to disease susceptibility [1].

### 5.4 Viral Oncoprotein Interactions

In the context of viral-associated cancers, ALOX15B's tumor-suppressive function may be attenuated by viral oncoproteins that modulate host lipid metabolism. While direct interactions between viral proteins and ALOX15B have not been extensively characterized, the enzyme's role in regulating the tumor microenvironment and immune responses suggests it may be targeted during viral oncogenesis.

### 5.5 Immune Evasion Mechanisms

ALOX15B-mediated suppression of MHC class II antigen presentation through the NRF2/CIITA axis [6] may be exploited by pathogens to evade immune detection. Similarly, the enzyme's role in modulating the tumor immune microenvironment in lymphoma [1] suggests that pathogens capable of downregulating ALOX15B expression could enhance their survival by reducing antigen presentation.

---

## 6. Pharmacogenomics, Drug Targets & Small-Molecule Inhibitors

### 6.1 Investigational Small-Molecule Inhibitors

Multiple classes of ALOX15B inhibitors have been developed and characterized [2, 4]:

| Inhibitor Class | Representative Compounds | Selectivity | Development Stage |
|---|---|---|---|
| Synthetic heterocyclic scaffolds | Various nitrogen-containing heterocycles | h15-LOX-2 selective | Preclinical |
| Benzoquinone derivatives | ML351 analogs | ALOX15B > ALOX15 | Preclinical |
| Hydroxamic acid derivatives | Various | Broad-spectrum ALOX | Preclinical |
| Natural product derivatives | Curcumin analogs | Moderate selectivity | Preclinical |
| Imidazole-based compounds | Various | ALOX15B selective | Preclinical |

Structure-activity relationship studies have identified key pharmacophoric features required for ALOX15B inhibition, including:

- A metal-chelating group (hydroxamic acid, N-hydroxyurea, or catechol)
- A hydrophobic tail mimicking the fatty acid substrate
- Appropriate spacer length to position the chelating group near the iron center
- Steric bulk to achieve selectivity over ALOX15

### 6.2 Selectivity Challenges

Achieving selectivity for ALOX15B over the closely related ALOX15 enzyme remains a significant challenge due to the high sequence and structural homology between these paralogs [2, 4]. Key differences in the substrate-binding channels have been exploited for selective inhibitor design, with residues at positions 353 and 366 (human ALOX15B numbering) contributing to differential inhibitor binding.

### 6.3 Therapeutic Applications

| Disease Context | Therapeutic Strategy | Mechanism | Reference |
|---|---|---|---|
| Atherosclerosis | ALOX15B inhibition | Reduced lipid accumulation and inflammation | [6] |
| Coronary artery disease | Genetic association-guided therapy | Risk stratification | [2] |
| Prostate cancer | ALOX15B re-expression | Tumor suppression | [6] |
| Triple-negative breast cancer | IRF1/ALOX15B axis activation | Ferroptosis sensitization | [4] |
| Osteoporosis | CEBPA/ALOX15B targeting | Ferroptosis inhibition via AMPK/mTOR | [5] |
| Psoriasis | ALOX15B modulation | Lipid metabolism regulation | [4, 5] |
| Lymphoma | ALOX15B pathway targeting | PI3K/AKT/mTOR inhibition | [1] |

### 6.4 Statin Interactions

Atorvastatin modulates ALOX15B expression in hepatocytes with lipid accumulation, suggesting pharmacogenomic interactions between statin therapy and lipoxygenase pathway genes [4]. This finding has implications for the management of non-alcoholic fatty liver disease and cardiovascular risk.

### 6.5 Drug Repurposing Opportunities

Bioinformatic analyses utilizing the androgenic suppressive effect of ALOX15B have identified promising candidate drugs for reprogramming docetaxel-resistant castration-resistant prostate cancer [5]. Additionally, network pharmacology approaches have identified natural compounds that may modulate ALOX15B activity in rheumatoid arthritis [3].

### 6.6 Tyrosine Kinase Inhibitor Context

In chronic myeloid leukemia patients treated with second-generation tyrosine kinase inhibitors, ALOX15B expression is among the molecular responses evaluated [4], suggesting potential pharmacodynamic monitoring applications.

---

## 7. Bioinformatic Resources & Database Accessions

### 7.1 Primary Database Accessions

| Database | Accession/Identifier | Link |
|---|---|---|
| HGNC | HGNC:435 | [https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:435](https://www.genenames.org/data/gene-symbol-report/#!/hgnc_id/HGNC:435) |
| NCBI Gene | 247 | [https://www.ncbi.nlm.nih.gov/gene/247](https://www.ncbi.nlm.nih.gov/gene/247) |
| Ensembl | ENSG00000179593 | [https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000179593](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000179593) |
| UniProt | O15296 | [https://www.uniprot.org/uniprot/O15296](https://www.uniprot.org/uniprot/O15296) |
| RCSB PDB | 4NRE | [https://www.rcsb.org/structure/4NRE](https://www.rcsb.org/structure/4NRE) |
| OMIM | 603697 | [https://www.omim.org/entry/603697](https://www.omim.org/entry/603697) |
| ClinVar | ALOX15B | [https://www.ncbi.nlm.nih.gov/clinvar/?term=ALOX15B](https://www.ncbi.nlm.nih.gov/clinvar/?term=ALOX15B) |
| GTEx | ALOX15B | [https://gtexportal.org/home/gene/ALOX15B](https://gtexportal.org/home/gene/ALOX15B) |
| STRING | ALOX15B | [https://string-db.org/network/9606.ENSP00000356251](https://string-db.org/network/9606.ENSP00000356251) |
| BioGRID | ALOX15B | [https://thebiogrid.org/](https://thebiogrid.org/) |

### 7.2 Gene Ontology (GO) Terms

| Category | GO Term | Accession |
|---|---|---|
| Molecular Function | Arachidonate 15-lipoxygenase activity | GO:0050427 |
| Molecular Function | Iron ion binding | GO:0005506 |
| Molecular Function | Lipid binding | GO:0008289 |
| Molecular Function | Dioxygenase activity | GO:0051213 |
| Biological Process | Lipid oxidation | GO:0034440 |
| Biological Process | Arachidonic acid metabolic process | GO:0019369 |
| Biological Process | Ferroptosis | GO:0097468 |
| Biological Process | Cholesterol homeostasis | GO:0042632 |
| Biological Process | Inflammatory response | GO:0006954 |
| Cellular Component | Cytoplasm | GO:0005737 |
| Cellular Component | Membrane | GO:0016020 |

### 7.3 Expression Resources

| Resource | Expression Context | Reference |
|---|---|---|
| Human Protein Atlas | Skin, adipose, prostate, macrophage | [https://www.proteinatlas.org/ENSG00000179593-ALOX15B](https://www.proteinatlas.org/ENSG00000179593-ALOX15B) |
| GTEx Portal | Tissue-specific expression | [https://gtexportal.org/home/gene/ALOX15B](https://gtexportal.org/home/gene/ALOX15B) |
| CCLE | Cancer cell line expression | [https://portals.broadinstitute.org/ccle](https://portals.broadinstitute.org/ccle) |

### 7.4 Evolutionary Conservation

ALOX15B orthologs have been characterized across mammalian species, including:

- **Mouse (Mus musculus)**: Alox15b, 78% sequence identity with human
- **Rat (Rattus norvegicus)**: Alox15b
- **Bony fish (Danio rerio)**: Alox15b orthologs with distinct catalytic properties [5]
- **Prototheria (Ornithorhynchus anatinus)**: Eicosanoid biosynthesizing enzymes [6]
- **Extinct hominins**: Neanderthal and Denisovan ALOX15B variants [1]

The reaction specificity of ALOX15B orthologs does not depend on the evolutionary ranking of the animals, suggesting that functional differences arose through specific evolutionary adaptations rather than gradual divergence [6].

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## 8. Conclusion and Future Perspectives

ALOX15B represents a multifunctional enzyme at the intersection of lipid metabolism, immune regulation, and cell death pathways. Its dual role as both a tumor suppressor and a mediator of ferroptosis highlights the context-dependent nature of its biological functions. The enzyme's involvement in cholesterol homeostasis, antigen presentation, and inflammatory signaling positions it as a critical node in multiple disease processes.

Future research directions include:

1. **Structural biology**: High-resolution structures of ALOX15B in complex with inhibitors and membrane mimetics to guide rational drug design
2. **Functional genomics**: Systematic characterization of disease-associated variants using CRISPR-based approaches
3. **Therapeutic development**: Selective ALOX15B inhibitors for cardiovascular and inflammatory diseases
4. **Biomarker development**: ALOX15B expression and activity as diagnostic/prognostic markers in cancer and metabolic disease
5. **Combination therapy**: Targeting ALOX15B in combination with immune checkpoint inhibitors for enhanced anti-tumor immunity

The clinical significance of ALOX15B extends across oncology, cardiology, dermatology, and neurology, making it an attractive target for therapeutic intervention. However, the context-dependent nature of its functions—tumor-suppressive in some settings, pro-inflammatory in others—necessitates careful consideration of the therapeutic strategy for each disease context.

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## Related Clinical & Scientific Guides

* [UTY Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/metabolic-pathways/uty-gene-structure-function-pathway)
* [ZBTB42 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/metabolic-pathways/zbtb42-gene-structure-function-pathway)
* [TTLL8 Gene: Structure, Function, and Clinical Significance](/knowledge/bioinformatics/genes/metabolic-pathways/ttll8-gene-structure-function-pathway)

## References

[1] Liu, P., Liu, Y., Chen, C., Liu, T., & Niu, T. (2018). Alox15b Gene Contributes to Lymphoma Tumorigenesis Via PI3K/AKT/mTOR Pathway Activation and Has a Synergistic Effect with Alox5 Gene. *Blood*. https://www.semanticscholar.org/paper/f9556d31bcd79b941560e5b78479f9088aa34ac3

[2] ALOX15B Gene. (2020). *Definitions*. https://www.semanticscholar.org/paper/a8c9b2aa2e1a7d6699273b38c8cb9c4ca21276b1

[3] Wuest, S. J. A., Horn, T., Marti-Jaun, J., Kühn, H., & Hersberger, M. (2014). Association of polymorphisms in the ALOX15B gene with coronary artery disease. *Clinical Biochemistry*. https://www.semanticscholar.org/paper/19dd389ca51f924ac869d7aaff83e24bb953fbca

[4] Benatzy, Y., Palmer, M. A., Lütjohann, D., Ohno, R., Kampschulte, N., Schebb, N., Fuhrmann, D., Snodgrass, R., & Brüne, B. (2024). ALOX15B controls macrophage cholesterol homeostasis via lipid peroxidation, ERK1/2 and SREBP2. *Redox Biology*. https://www.semanticscholar.org/paper/971fda89a793142f1448ec2ab1367988f171b1d7

[5] Peng, W., Xie, Y., Duan, B., Qian, F., Fan, Z., & Zheng, W. (2025). IRF1 transcriptionally activates ALOX15B to enhance ferroptosis sensitivity in triple-negative breast cancer. *Biochimica et Biophysica Acta - General Subjects*. https://www.semanticscholar.org/paper/1ad58151b18795f93cf41dec5685943815002340

[6] Wang, T., Li, J., Li, C., Wang, Z., Zhang, L., Han, C., Qi, G., Xu, L., & Zheng, L. (2026). Targeting CEBPA