PD-L1 expression in HNPCC-associated colorectal cancer.

BACKGROUND: PD-L1 immunohistochemistry is predictive for molecular inhibitors of PD-1/PD-L1 immune checkpoint. Therefore, this study evaluated the PD-L1 expression in patients with Hereditary Non-Polyposis Colorectal Cancer (HNPCC). METHODS: Immunohistochemical expression of PD-L1 in carcinoma cells, stromal macrophages and lymphocytes of 40 HNPCC-patients with colorectal cancer was scored semi-quantitatively. RESULTS: Focal (2 cases) to extensive (2 cases) PD-L1-immunopositivity of carcinoma cells was detected in 4 out of 40 cases (10.0%). Stromal macrophages were immunopositive in 28 out of 40 cases (70.0%). Lymphocytes showed PD-L1 expression in 3 out of 40 cases (7.5%). Simultaneous immunopositivity of stromal macrophages and tumor cells was detected in two MLH1/PMS2-deficient and two MSH2/MSH6-deficient cases. CONCLUSION: A subset of HNPCC-associated colorectal cancers in this study clearly showed PD-L1 expression of tumor epithelia and immune cells, therefore, the detection of PD-L1 status is useful.

Tumoral expression of nuclear cofactor FHL2 is associated with lymphatic metastasis in sporadic but not in HNPCC-associated colorectal cancer.

BACKGROUND: Four and a half LIM domain protein-2 (FHL2) is part of the focal adhesion structures modulating cell motility. FHL2 may translocate into the nucleus serving as a transcriptional cofactor binding several transcription factors. Overexpression of FHL2 has been linked to cancer progression in various neoplasias. The aim of the present study was to determine, whether FHL2's function as nuclear cofactor plays a prognostic role in invading tumor cells of sporadic and HNPCC-associated colorectal cancer (CRC). DESIGN: Immunohistochemical staining intensity of nuclear FHL2 was quantified by Remmele score analysing 47 sporadic and 42 HNPCC-associated colorectal cancers. Analysis was restricted to carcinoma cells of the tumoral invasion front. RESULTS: Confocal microscopy detected nuclear expression of FHL2 in colon cancer cells and absence of nuclear FHL2 signal in normal colon enterocytes. In colon cancer, nuclear FHL2 expression was predominantly observed in low-differentiated, often mucinous tumor areas. 42.55% of sporadic and 54.76% of HNPCC-associated CRC showed enhanced (Remmele score 6-12) nuclear FHL2 expression in the carcinoma cells of the tumoral advancing edge. Enhanced nuclear FHL2 expression was significantly linked to lymphatic metastasis in sporadic CRC (p=0.0197) and almost reached significance in HNPCC-associated CRC (p=0.0545). In contrast, nuclear FHL2 expression was neither associated with hematogenic metastasis in sporadic (p=0.7087) nor in HNPCC-associated colorectal cancer (p=0.3007). CONCLUSIONS: We recently demonstrated that enhanced nuclear FHL2 expression in tumor stroma of sporadic colon cancer is associated with lymphatic metastasis. The results of the present study indicate a synergistic effect of nuclear cofactor FHL2 in tumor cells as well as in peritumoral stroma cells promoting lymphatic metastasis in sporadic CRC. As HNPCC-associated tumors did not show a significant association between tumoral nuclear FHL2 expression and lymphatic metastasis we speculate, that the intensive lymphocytic immune response in HNPCC precludes a direct contact of tumor cells and stromal cells resulting in reduced lymphatic spread.

TGF-ß1-dependent induction and nuclear translocation of FHL2 promotes keratin expression in pilomatricoma.

Pilomatricoma is a tumour derived from hair matrix cells, which shows progressive keratin expression. Tumorigenesis is frequently associated with activating mutations in ß-catenin gene inducing nuclear expression of ß-catenin protein. The present study analysed the role of transforming growth factor-ß1 (TGF-ß1) and four-and-a-half LIM domain protein 2 (FHL2) in pilomatricoma in synopsis with their expression patterns in human anagen hair. Human anagen hair showed TGF-ß1 and nuclear FHL2 expression in the outer root sheath layer separated from nuclear ß-catenin staining, which was observed in cells of matrix and inner root sheath layers. Correspondingly, 41 out of 50 pilomatricomas showed co-labelling of TGF-ß1 and nuclear FHL2 in tumour cells, which mostly lacked nuclear ß-catenin expression. Tumoural proliferation (ki67) was associated with nuclear ß-catenin staining but not with expression of nuclear FHL2. In early pilomatricomas, TGF-ß1 expression was observed in few peripheral tumour cells showing absent or faint nuclear FHL2 co-staining. TGF-ß1 expression extended in growing tumours going along with strong nuclear FHL2 co-labelling as well as progressive keratin 14 and keratin 1 expression. In vitro, cultured human keratinocytes showed weak to marked autocrine TGF-ß1 expression; in case of enhanced TGF-ß1 expression associated with keratin 10 staining. TGF-ß1-treatment of cultured human keratinocytes induced nuclear and cytoplasmatic FHL2 staining as well as keratin 14 staining. Accordingly, siRNA-mediated FHL2 knockdown of TGF-ß1-stimulated keratinocytes reduced keratin 14 staining. In conclusion, tumoural TGF-ß1 secretion seems to induce nuclear translocation of co-factor FHL2 mediating progressive keratin expression in pilomatricoma.