• Origin: The MC38 cell line is derived from C57BL/6 murine colon adenocarcinoma cells. The cell line is a commonly used murine model for colorectal carcinoma.
• Background Information: Protein tyrosine kinase 7 (PTK7) is a Wnt co-receptor that is expressed at low levels in epithelial, endothelial, and hematopoietic tissues. However, its mRNA levels are significantly elevated in colon cancer, gastric cancer, lung cancer, and acute myeloid leukemia, making it a potential target for anti-cancer therapies. Several drugs are currently being developed that target PTK7.. 
• Gene targeting strategy: The exogenous promoter, human PTK7 coding sequence and puromycin resistance gene were inserted to replace part of murine exon 2 and all of exon 3 to exon 5. The insertion disrupts the endogenous murine Ptk7 gene, resulting in a non-functional transcript.
• Tumorigenicity: Confirmed in C57BL/6 mice, B-hPTK7 mice.
• Application: The B-hPTK7 MC38 tumor models can be used for preclinical evaluation of monoclonal antibody drugs targeting human PTK7.
• Notes: 

        When B-hPTK7 MC38 cells were implanted into heterozygous B-hPTK7 mice, one mouse exhibited tumor regression at the endpoint of the experiment. It is recommended that each group contain at least 8 mice.
         The growth rate of B-hPTK7 MC38 in C57BL/6J mice is slower than that of MC38, indicating the possibility of immunogenicity.

PTK7 expression analysis in B-hPTK7 MC38 cells by flow cytometry. Single cell suspensions from wild-type MC38 and B-hPTK7 MC38 #2-B09 cultures were analyzed with anti-human PTK7 antibody Cofetuzumab analog (in house) by flow cytometry. Human PTK7 was detected on the surface of B-hPTK7 MC38 cells but not wild-type MC38 cells. 

Subcutaneous tumor growth of B-hPTK7 MC38 cells. B-hPTK7 MC38 cells (5x10⁵) and wild-type MC38 cells (5x10⁵) were subcutaneously implanted into heterozygous B-hPTK7 mice (7-week-old, n=5). Tumor volume and body weight were measured twice a week. (A) Average tumor volume. (B) Body weight. Volume was expressed in mm³ using the formula: V=0.5 X long diameter X short diameter². Results indicate that B-hPTK7 MC38 cells were able to establish tumors in vivo and can be used for efficacy studies. Values are expressed as mean ± SEM. 

Tumor growth curve & body weight changes

Subcutaneous tumor growth of B-hPTK7 MC38 cells. B-hPTK7 MC38 cells (5x10⁵) and wild-type MC38 cells (5x10⁵) were subcutaneously implanted into heterozygous C57BL/6J mice (7-week-old, n=5). Tumor volume and body weight were measured twice a week. (A) Average tumor volume. (B) Body weight. Volume was expressed in mm³ using the formula: V=0.5 X long diameter X short diameter². Results indicate that B-hPTK7 MC38 cells were able to establish tumors in vivo and can be used for efficacy studies. Values are expressed as mean ± SEM.