GPC3: GPC3 is a tumor-associated heparan sulfate proteoglycan that promotes cancer growth and serves as a therapeutic target.

• Gene Information: GPC3 (Glypican-3) is a GPI-anchored cell surface heparan sulfate proteoglycan encoded on human chromosome X and a well-known tumor-associated antigen.
• Protein Expression: GPC3 is highly expressed during embryonic development and is largely absent in most normal adult tissues. It is frequently re-expressed in cancers, especially hepatocellular carcinoma, making it an attractive tumor-associated antigen.
• Signaling Pathway: GPC3 modulates oncogenic signaling pathways, particularly Wnt/β-catenin signaling, to promote tumor cell proliferation and survival. It also interacts with growth factors and contributes to tumor progression.
• Therapeutic Targeting: GPC3-targeted antibodies, ADCs, bispecific antibodies, TCE and CAR-T cells selectively eliminate GPC3-positive tumor cells.

GPC3

• The human GPC3 CDS was inserted after the exon 3 of mouse Gpc3 gene in B-hGPC3 mice. The insertion disrupts the endogenous murine Gpc3 gene.
• The chimeric GPC3 protein expression will be driven by endogenous mouse Gpc3 promoter, while mouse Gpc3 gene transcription and translation will be disrupted.

• Mouse Gpc3 mRNA was detectable only in kidney of wild-type C57BL/6 mice.
• Human GPC3 mRNA was detectable only in homozygous B-hGPC3 mice, but not in wild-type mice.

mRNA GPC3 was detectable in B-hGPC3 mice by RT-PCR and sequencing. Kidney tissues were isolated from wild-type C57BL/6 mice (+/+) and homozygous B-hGPC3 mice (H/H). Primers were designed to detect the human and mouse GPC3. Sequencing of the PCR products confirmed that the amplified sequences were consistent with database reference sequences.

• Human GPC3 was detectable in homozygous B-hGPC3 mice, but not in wild type mice. 

Immunohistochemical (IHC) analysis of GPC3 protein expression in C57BL/6 wild-type mice and B-hGPC3 mice. The liver and fetal liver were collected from C57BL/6 (+/+) and homozygous B-hGPC3 mice (H/H) and analyzed by IHC with anti-GPC3 antibody (GC33-hIgG1 analog, in house). The arrow indicates tissue cells with positive GPC3 staining (brown).

• Human GPC3 was detected in the fetal liver (H) of homozygous B-hGPC3 mice.
• There was no detectable expression of hGPC3 in various tissues of C57BL/6.

Immunohistochemical (IHC) analysis of GPC3 protein expression in C57BL/6 wild-type mice and B-hGPC3 mice. Nine major tissues were collected from C57BL/6 mice and homozygous B-hGPC3 mice (female/male, 8-week-old), and analyzed by IHC with anti-GPC3 antibody (GC33-hIgG1 analog, in house).  Human GPC3 was detected in the fetal liver (H) of homozygous B-hGPC3 mice (Figure 2). There was no detectable expression of hGPC3 in various tissues of C57BL/6 (Figure 1). A summary of the expression levels in various tissues of C57BL/6 and B-hGPC3 is presented in Table 1.

Note: In both C57BL/6 and B-hGPC3 mice, staining can be observed in the heart. however, since the positive tissue (fetal liver) specifically recognizes hGPC3 with the antibody, it can be inferred that the staining in the heart is non-specific.