Prevalence and clinical significance of Claudin-3 expression in cancer: a tissue microarray study on 14,966 tumor samples

Abstract

Background: Claudin-3 (CLDN3) participates in the formation of the tight-junctions (TJs) that regulate intercellular permeability. Altered CLDN3 expression has been linked to tumor progression in multiple tumor types. Despite its widespread expression in normal epithelial cells, CLDN3 is considered an attractive drug target candidate, since it may be more accessible in cancer cells than in normal cells due to their less orchestrated cell growth.

Methods: To comprehensively determine the prevalence of CLDN3 expression in cancer, a tissue microarray containing 14,966 samples from 133 different tumor types and subtypes as well as 608 samples of 76 different normal tissue types was analyzed by immunohistochemistry.

Results: CLDN3 immunostaining was observed in 8,479 (68.9%) of 12,314 analyzable tumors, including 11.6% with weak, 6.2% with moderate, and 51.1% with strong positivity. CLDN3 staining was found in 96 of 133 tumor categories, 80 of which contained at least one strongly positive case. CLDN3 positivity was most seen in neuroendocrine neoplasms (92-100%) and in adenocarcinomas (67-100%), tumors of the female genital tract, including various subtypes of ovarian and endometrial carcinoma (up to 100%), as well as different subtypes of breast cancer (95.3-100%). CLDN3 positivity was less common in squamous cell carcinomas (0-43.2%) and mainly absent in melanoma, mesenchymal, and hematolymphatic neoplasms. In clear cell renal cell carcinoma (ccRCC), low CLDN3 was strongly linked to poor ISUP (p < 0.0001), Fuhrman (p < 0.0001), and Thoenes (p < 0.0001) grades, advanced pT category (p < 0.0001), high UICC stage (p = 0.0006) and distant metastasis (p = 0.0011), as well as shortened overall (p = 0.0118) and recurrence-free (p < 0.0001) survival. In papillary RCC (pRCC), low CLDN3 was associated with poor grade (p < 0.05), high pT (p = 0.0273) and distant metastasis (p = 0.0357). In urothelial carcinoma high CLDN3 was linked to high grade (p < 0.0001) and nodal metastasis (p = 0.0111). The level of CLDN3 staining was unrelated to parameters of tumor aggressiveness in pancreatic, gastric, and breast cancer.

Conclusion: In conclusion, our data demonstrate significant levels of CLDN3 expression in many different tumor entities and identify reduced CLDN3 expression as a potential prognostic marker in RCC.

Keywords: Biomarker; CLDN3; Cancer; Renal cell carcinoma; Tissue microarray.

Fig. 1

CLDN3 immunostaining of normal tissues. The panels show a strong membranous CLDN3 immunostaining of the luminal cells of breast glands (a) and of the prostate (b), epithelial cells of the fallopian tube (c), a small subset of gastric epithelial cells in the neck and in glandular pits (d), epithelial cells of the colorectum (e), the upper half of urothelial cells (f), and in collecting ducts of the kidney medulla (g) while CLDN3 staining is absent in squamous epithelial cells of the epidermis (h)

Fig. 2

CLDN3 immunostaining in cancer. CLDN3 immunostaining was purely membranous in most tumors, with some showing an additional cytoplasmic positivity. The panels show a strong CLDN3 positivity in cancer cells of a neuroendocrine tumor of the appendix (a), an adenocarcinoma of the prostate (b), an endometrioid endometrial carcinoma (c), an invasive breast cancer of no special type (d), a muscle-invasive urothelial carcinoma (e), and clear cell renal cell carcinoma (f). CLDN3 staining is lacking in another clear cell renal cell carcinoma (g) and squamous cell carcinoma of the lung (h)

Fig. 3

Ranking order of CLDN3 positive immunostaining in different human tumors.In ccRCC, low CLDN3 staining was strongly linked to poor ISUP (p < 0.0001), Fuhrman (p < 0.0001), and Thoenes (p < 0.0001) grades, advanced pT stage (p < 0.0001), high UICC stage (p = 0.0006), distant metastasis (p = 0.0011), as well as shortened overall (p = 0.0118; Fig. 4a) and recurrence-free (p < 0.0001; Fig. 4b) survival

Fig. 4

CLDN3 immunostaining and recurrence-free (A) and overall survival (B) in clear cell renal cell carcinoma

Fig. 5

CLDN3 protein expression in cancer (own findings vs. literature data). Graphical representation of CLDN3 data from this study (X) compared to the previous literature. The colors of the dots represent the number of tumors analyzed in these studies: red: n ≤ 20; yellow: n = 21 to 100; green: n > 100. For raw data and references, see suppl. Tab. 1