Collagen molecular phenotypic switch between non-neoplastic and neoplastic canine mammary tissues

Masahiko Terajima,Shunji Hattori,Katsuhiro Uzawa,Amy C Durham,Becky K Brisson,Tomoaki Saito,Yuki Taga,Susan W Volk,Karin U Sørenmo,Kotaro Sato,Mitsuo Yamauchi

doi:10.1038/s41598-021-87380-y

Abstract

In spite of major advances over the past several decades in diagnosis and treatment, breast cancer remains a global cause of morbidity and premature death for both human and veterinary patients. Due to multiple shared clinicopathological features, dogs provide an excellent model of human breast cancer, thus, a comparative oncology approach may advance our understanding of breast cancer biology and improve patient outcomes. Despite an increasing awareness of the critical role of fibrillar collagens in breast cancer biology, tumor-permissive collagen features are still ill-defined. Here, we characterize the molecular and morphological phenotypes of type I collagen in canine mammary gland tumors. Canine mammary carcinoma samples contained longer collagen fibers as well as a greater population of wider fibers compared to non-neoplastic and adenoma samples. Furthermore, the total number of collagen cross-links enriched in the stable hydroxylysine-aldehyde derived cross-links was significantly increased in neoplastic mammary gland samples compared to non-neoplastic mammary gland tissue. The mass spectrometric analyses of type I collagen revealed that in malignant mammary tumor samples, lysine residues, in particular those in the telopeptides, were markedly over-hydroxylated in comparison to non-neoplastic mammary tissue. The extent of glycosylation of hydroxylysine residues was comparable among the groups. Consistent with these data, expression levels of genes encoding lysyl hydroxylase 2 (LH2) and its molecular chaperone FK506-binding protein 65 were both significantly increased in neoplastic samples. These alterations likely lead to an increase in the LH2-mediated stable collagen cross-links in mammary carcinoma that may promote tumor cell metastasis in these patients.

Highlights

In spite of major advances over the past several decades in diagnosis and treatment, breast cancer remains a global cause of morbidity and premature death for both human and veterinary patients
Areas of non-neoplastic mammary tissue, mammary adenoma and mammary carcinoma were identified from hematoxylin and eosin (H&E)-stained histologic slides obtained from biopsy samples from dogs undergoing treatment for mammary tumors and fibrillar collagen was imaged in corresponding regions using second harmonic generation (SHG) microscopy
When the individual fiber characteristics were analyzed in SHG images using the CT-FIRE program, significant differences were noted associated with malignancy, while values between non-neoplastic and adenoma samples were similar (Fig. 1j–m)

Summary

Introduction

In spite of major advances over the past several decades in diagnosis and treatment, breast cancer remains a global cause of morbidity and premature death for both human and veterinary patients. Consistent with these data, expression levels of genes encoding lysyl hydroxylase 2 (LH2) and its molecular chaperone FK506-binding protein 65 were both significantly increased in neoplastic samples These alterations likely lead to an increase in the LH2-mediated stable collagen cross-links in mammary carcinoma that may promote tumor cell metastasis in these patients. Collagen cross-linking is initiated in the extracellular space by the oxidative deamination of Lys and Hyl residues in the N- and C-telo domains (α1-9N/16C and α2-5N in the case of type I collagen) to the respective aldehydes, L ysald or Hylald, through the action of lysyl oxidases (LOX, LOXL1-4). The quantity and quality/stability of collagen cross-links are mainly determined by LOX/LOXLs and LHs (LH2 in particular) activities, respectively

Methods

Results

Conclusion