Abstract:

Objective

To investigate the expression of the forkhead box C1 （FOXC1） and the tight junction protein claudin-4 in triple-negative breast cancer （TNBC） and their relationships with the tumor microenvironment （TME）-related and inflammatory factors.

Methods

According to the inclusion and exclusion criteria， a retrospective study was conducted on 72 TNBC patients in the Maternal and Children's Hospital of Qinhuangdao from January 2021 to June 2023. According to the immunohistochemical results， the patients were divided into the FOXC1-positive group （40 cases） and the FOXC1-negative group （32 cases） or they were divided into the claudin-4-positive group （50 cases） and the claudin-4-negative group （22 cases）.In addition， 30 cases of non-TNBC patients admitted during the same period served as control. The levels of tumor microenvironment-related factors ［transforming growth factor-β1 （TGF-β1）， α-smooth muscle actin （α-SMA）， and type I collagen］and inflammation-related factors ［interleukin-6 （IL-6）， white blood cell count（WBC）， and tumor necrosis factor-α （TNF-α）］were compared among three groups. One-way analysis of variance was used for comparisons between groups， and the Bonferroni method was used for pairwise comparisons， with the significance level adjusted to 0.017. The Pearson method was used to analyze the correlations between FOXC1/ claudin-4 and TME-related and inflammatory factors.

Results

There were significant differences in the levels of TGF-β1， α-SMA， and type I collagen，TNF-α， IL-6， and WBC count among the FOXC1-positive group， the FOXC1-negative group and the control group （F=16.792， 18.160，14.255， 32.401， 27.269， 25.507； all P＜0.001）. The levels of all the above-mentioned parameters in the FOXC1-positive group were significantly higher than those in the FOXC1-negative group and the control group，and the values in the FOXC1-negative group were significantly higher than those in the control group （all P＜0.017）. There were significant differences in the levels of TGF-β1， α-SMA， and type I collagen，TNF-α， IL-6，and WBC count among the claudin-4-positive group， the claudin-4-negative group， and the control group （F=17.535， 13.640， 20.900， 21.351， 27.353， 24.180； all P＜0.001）. The levels of all the above-mentioned parameters in the claudin-4-positive group were significantly higher than those in the FOXC1-negative group and the control group， and the values in the claudin-4-negative group were significantly higher than those in the control group （P＜0.017）. Both FOXC1 and claudin-4 expressions were positively correlated with the expressions of TGF-β1， α-SMA and type I collagen and the levels of serum TNF-α， IL-6， and WBC count（r=0.632， 0.710， 0.667， 0.684， 0.598， 0.601， all P＜0.001； r=0.723， 0.611， 0.621， 0.702， 0.582，0.570， all P＜0.001）.

Conclusion

The proteins FOXC1 and claudin-4 are highly expressed in the TNBC tissues， which may be related to the TME-related and inflammatory factors.

Key words: Forkhead box protein 1, claudin-4, Triple negative breast cancer, Tumor microenvironment