XAGE1A Human

What is XAGE1A and what protein family does it belong to?

XAGE1A (X antigen family member 1) is a member of the XAGE subfamily, which belongs to the larger GAGE family of proteins . It is classified as a cancer/testis antigen (CTA), a group of proteins predominantly expressed in testis tissue and various cancer types . XAGE1A contains a nuclear localization signal and shares sequence similarity with other GAGE/PAGE proteins . The gene is located on the X chromosome, with the full-length cDNA containing 611 bp that encodes a protein of approximately 16.3 kDa . The protein exhibits potential transmembrane domains at the N-terminus and shares homology with GAGE/PAGE proteins at the C-terminal end .

What are the known transcript variants of XAGE1A and their expression patterns?

Four transcript variants of XAGE1 have been identified: XAGE-1a, XAGE-1b, XAGE-1c, and XAGE-1d . These variants result from alternative splicing and alternative transcription start sites . Research utilizing reverse transcription-PCR analysis of non-small cell lung cancer (NSCLC) specimens has demonstrated that XAGE-1b and XAGE-1d mRNA are the predominantly expressed variants in cancer tissues, detected in 15 and 6 of 49 lung cancer specimens, respectively . Notably, XAGE-1a and XAGE-1c mRNA expression was not observed in these samples . The XAGE-1b variant shows particularly high expression in lung adenocarcinoma, found in 45% (14 of 31) of adenocarcinoma samples compared to only 6% (1 of 18) in other histological types of lung cancer .

What cancer types commonly express XAGE1A?

XAGE1A demonstrates a distinctive expression pattern across various cancer types:

XAGE1 shows particularly high expression in lung adenocarcinoma and Ewing's sarcoma . The protein was originally identified through expressed sequence tag database analysis searching for PAGE/GAGE-related genes, revealing its frequent presence in Ewing's sarcoma and alveolar rhabdomyosarcoma . Northern blot and RNA dot blot analyses have confirmed high expression in normal testis tissue alongside these cancer types .

How does XAGE1A expression correlate with clinical outcomes in cancer patients?

What methods are most effective for detecting XAGE1A expression in research and clinical samples?

Multiple complementary techniques are recommended for comprehensive XAGE1A detection:

Transcriptional Analysis:

• Conventional 30-cycle reverse transcription-PCR detects XAGE1 mRNA variants

• Real-time reverse transcription-PCR provides quantitative assessment of expression levels

• Northern blots and RNA dot blots can confirm expression in tissue samples

Protein Detection:

• Immunohistochemistry using XAGE1-specific monoclonal antibodies is effective for tissue samples and correlates well with mRNA expression (14 of 15 XAGE1b mRNA-positive specimens showed protein expression by IHC)

• Western blot analysis can be used to confirm antibody specificity and for serum antibody detection

• ELISA assays are effective for screening humoral immune responses against XAGE1

When performing these analyses, researchers should note that different transcript variants show distinct expression patterns. Studies have found that while XAGE-1b and XAGE-1d are detected in cancer samples, XAGE-1a and XAGE-1c are generally not observed .

What experimental models are appropriate for studying XAGE1A function?

Based on the search results, several experimental models have proven effective:

Cell Line Models:

• Ewing's sarcoma cell lines show high XAGE1 expression (7 of 8 tested lines)

• Lung adenocarcinoma cell lines expressing XAGE1 can be used for functional studies

Recombinant Protein Systems:

• E. coli expression systems yield functional recombinant XAGE1A protein with >85% purity

• His-tagged versions facilitate purification and detection in experimental settings

Clinical Sample Analysis:

• Patient tumor specimens (particularly lung adenocarcinoma and Ewing's sarcoma)

• Matched serum samples for humoral immune response assessment

• Peripheral blood lymphocytes for T-cell response analysis

When establishing new experimental models, researchers should consider the variant-specific expression patterns and select appropriate detection methods based on whether they are investigating transcriptional regulation, protein function, or immunological responses.

What is known about humoral immune responses against XAGE1A in cancer patients?

XAGE1A is highly immunogenic, triggering measurable antibody responses in a subset of cancer patients. The prevalence of XAGE1 antibody responses varies by cancer stage and type:

• In pathological stage I-IIIA lung adenocarcinoma: 6% (9/155) of patients develop antibody responses

• In clinical stage IIIB-IV lung adenocarcinoma: 20% (34/167) of patients show antibody responses

• Higher antibody response rates correlate with more advanced disease stages

Methods for detecting humoral immune responses include ELISA and Western blot techniques, with concordant results between these approaches .

How does XAGE1A affect T-cell responses in cancer patients?

XAGE1A not only triggers humoral immunity but also elicits significant T-cell responses. In patients who develop XAGE1 antibodies, both CD4+ and CD8+ T-cell responses are frequently observed . Phenotypic and functional analyses of T cells from these patients demonstrate indicators of immune activation .

These findings suggest that XAGE1A can induce coordinated immune responses involving both humoral and cellular immunity. The presence of both antibody and T-cell responses likely contributes to the improved clinical outcomes observed in antibody-positive patients .

What properties make XAGE1A a potential target for cancer immunotherapy?

XAGE1A possesses several characteristics that make it an attractive immunotherapy target:

• Restricted expression pattern: XAGE1A is predominantly expressed in testis (an immune-privileged site) and cancer tissues, minimizing the risk of autoimmune reactions

• High immunogenicity: XAGE1A can naturally induce both antibody and T-cell responses in patients

• Prevalence in specific cancers: High expression in approximately 40% of lung adenocarcinomas and many Ewing's sarcomas provides a substantial patient population

• Correlation with outcomes: The presence of anti-XAGE1 immune responses correlates with improved survival, suggesting therapeutic potential

• Variant-specific targeting: The predominant expression of specific variants (particularly XAGE-1b in lung adenocarcinoma) allows for precise targeting

These properties collectively suggest that XAGE1A-targeted immunotherapies could be effective, particularly for lung adenocarcinoma patients whose tumors express this antigen .

What methodological challenges exist in developing XAGE1A-targeted therapies?

Several technical challenges need to be addressed when developing XAGE1A-targeted therapies:

• Variant specificity: Different XAGE1 variants show distinct expression patterns, requiring variant-specific targeting strategies

• Expression heterogeneity: Variable expression levels across tumors and patients necessitate robust detection methods

• Immune escape mechanisms: The correlation between XAGE1 and immune checkpoint molecules suggests potential immune resistance that may require combination approaches

• Patient selection: The need to identify patients with XAGE1-positive tumors who might benefit from targeted therapies requires reliable biomarker assays

• Monitoring immune responses: Developing standardized methods to assess both humoral and cellular immune responses against XAGE1 during treatment

Researchers developing XAGE1A-targeted therapies should consider these challenges when designing clinical trials and selecting appropriate patient populations.

What are the optimal conditions for handling recombinant XAGE1A protein?

Recombinant XAGE1A protein requires specific handling conditions for optimal stability and experimental utility:

• Storage conditions: Store at 4°C if using within 2-4 weeks; for longer periods, store frozen at -20°C

• Buffer composition: Typically supplied in 20mM Tris-HCl buffer (pH 8.0), 0.2M NaCl, 20% glycerol, and 2mM DTT at a concentration of 0.25mg/ml

• Stability enhancement: For long-term storage, adding a carrier protein (0.1% HSA or BSA) is recommended

• Freeze-thaw management: Multiple freeze-thaw cycles should be avoided to maintain protein integrity

• Purity considerations: Commercially available recombinant proteins typically have >85% purity as determined by SDS-PAGE

These handling recommendations ensure that the recombinant protein maintains its structural integrity and functional properties for experimental applications.

What experimental applications can utilize recombinant XAGE1A protein?

Recombinant XAGE1A protein can be used in various research applications:

• Protein interaction studies: Identifying binding partners and molecular interactions

• Antibody production: Generating and validating antibodies for detection and functional studies

• Immunological assays: Serving as a target antigen in T-cell activation assays or antibody detection assays

• Structural analysis: Mass spectrometry and other structural biology techniques

• Vaccine development: Testing potential cancer vaccine formulations targeting XAGE1A

• Biomarker validation: Establishing and validating assays for XAGE1A detection in clinical samples

When designing experiments using recombinant XAGE1A, researchers should consider the specific variant being used and ensure appropriate controls to account for the presence of fusion tags (such as His-tags) that may affect protein behavior .