CD105 expression in cancer-associated fibroblasts: a biomarker for bone metastasis in early invasive ductal breast cancer patients

Abstract

Introduction: Bone metastasis is one of the causes that mainly decrease survival in patients with advanced breast cancer. Therefore, it is essential to find prognostic markers for the occurrence of this type of metastasis during the early stage of the disease. Currently, cancer-associated fibroblasts, which represent 80% of the fibroblasts present in the tumor microenvironment, are an interesting target for studying new biomarkers and developing alternative therapies. This study evaluated the prognostic significance of the CD105 expression in cancer-associated fibroblasts in early breast cancer patients. Methods: Immunohistochemistry was used to assess CD105 expression in invasive ductal breast carcinomas (n = 342), analyzing its association with clinical and pathological characteristics. Results: High CD105 expression in cancer-associated fibroblasts was associated with an increased risk of metastatic occurrence (p = 0.0003), particularly bone metastasis (p = 0.0005). Furthermore, high CD105 expression was associated with shorter metastasis-free survival, bone metastasis-free survival, and overall survival (p = 0.0002, 0.0006, and 0.0002, respectively). CD105 expression also constituted an independent prognostic factor for metastasis-free survival, bone metastasis-free survival, and overall survival (p = 0.0003, 0.0006, and 0.0001, respectively). Discussion: The high CD105 expression in cancer-associated fibroblasts is an independent prognostic marker for bone metastasis in early breast cancer patients. Therefore, the evaluation of CD105(+) CAFs could be crucial to stratify BCPs based on their individual risk profile for the development of BM, enhancing treatment strategies and outcomes.

Keywords: CD105; bone metastasis; breast cancer; cancer-associated fibroblasts; prognosis factor.

FIGURE 1

(A) Expression of CD105 and CD34 in stromal cells from the primary tumor of breast cancer patients. Top panel: Double immunohistochemistry for CD105 and CD34 (detected by brown and red chromogen, respectively) presents a representative example of co-staining of CD105 and CD34 in endothelial cells (•) and exclusive CD105-positive staining in evaluated stromal cells () of primary tumor tissue from a breast cancer patient. Bottom panel: Negative isotype controls. Nuclei were counterstained with hematoxylin (purple). Original magnification: ×200. Scale bars represent 200 μm and 100 μm in the inset. (B) Expression of CD105 in breast cancer and its different subtypes. Association of CD105 expression in cancer-associated fibroblast with different breast cancer subtypes. Fisher’s exact test was used to assess the association between variables, * p-value <0.050. (C) Histogram representing the association of CD105 expression in these stromal cells with different breast cancer subtypes. (D) Heatmap illustrating the distribution of CD105 expression across all samples included in the study, including cases with bone, visceral, and mix metastasis (BM, VS. mix M, respectively).

FIGURE 2

Association of CD105 expression with local relapse-free survival (RFS), metastasis-free survival (MFS), bone metastasis-free survival (BMFS), visceral metastasis-free survival (VMFS), mix metastasis-free survival (mix MFS), and overall survival (OS) in patients with early invasive ductal breast cancer. (A) Kaplan-Meier curves (univariate analysis) marked in red represent data from samples with high CD105 expression, while blue curves represent samples with negative/low CD105 expression. Log Rank (Mantel-Cox) test was used to assess the Kaplan-Meier curves. * p-value < 0.050. (B) Details of local RFS, MFS, BMFS, VMFS, mix MFS, and OS correspond to the low and high CD105 expression groups.

FIGURE 3

CD105 expression in CAFs and its relationship with anarchic breast microcalcifications and bone pain. (A) Association of CD105 expression with the presence of anarchic microcalcifications and bone pain prior to bone metastasis. Fisher’s exact test was used to assess the association between variables, * p-value <0.050. (B) Graphical representation of the aforementioned associations and the presence of microcalcifications and bone metastasis (BM).

FIGURE 4

Representative images of the relationship between histological characteristics of the breast tumor and CD105 expression. Hematoxylin and eosin staining were utilized to assess the histological characteristics of the stroma in the primary breast tumor. This figure illustrates samples exhibiting different levels of intratumoral stroma, fibroblasts, desmoplasia, myxoid changes, microcalcifications, collagen deposition, lymphocytic infiltration, and blood/lymphatic vascularization in relation to the expression of CD105. The images were captured at an original magnification of ×200, and the scale bars represent 200 μm.

FIGURE 5

CD105 mRNA Expression in FSP (+), FAP (+), and CD34 (−) cells within the breast cancer tumor using a bioinformatics approach. (A) Association of CD105 expression in stromal cells (fibroblast-like) with classical prognostic markers, local relapse, metastatic occurrence, bone metastatic occurrence, visceral metastatic occurrence, and mix metastatic occurrence in 105 patients with early invasive ductal breast cancer from the METABRIC breast cancer dataset. Fisher’s exact test was utilized to assess the association between variables, with a * p-value <0.050. (B), (C) Graphical representation of the associations between CD105 expression and classical prognostic factors, as well as other clinicopathological data. (D) Kaplan-Meier curves (univariate analysis) marked in red represent data from samples with high CD105 expression, while blue curves represent samples with negative/low CD105 expression. The Log Rank (Mantel-Cox) test was employed to evaluate the Kaplan-Meier curves, with a * p-value <0.050.