Assessment of Ovarian Tumor Growth in Wild-Type and Lumican-Deficient Mice: Insights Using Infrared Spectral Imaging, Histopathology, and Immunohistochemistry.

Pierre Nizet,Camille Boulagnon-Rombi,Ganesh D Sockalingum,Valérie Untereiner,Isabelle Proult,Stéphane Brézillon,Christèle Sellier,Lise Nannan,Romain Rivet,Laurent Ramont,Albin Jeanne,Christine Terryn

doi:10.3390/cancers13235950

Abstract

Simple SummaryLumican, a small leucine-rich proteoglycan (SLRP), maintains extracellular matrix (ECM) integrity while inhibiting melanoma primary tumor development, as well as metastatic spread. The aim of this study was to analyze the effect of lumican on tumor growth of murine ovarian carcinoma. C57BL/6 wild type mice (n = 12) and lumican-deficient mice (n = 10) were subcutaneously injected with murine ovarian epithelial carcinoma ID8 cells, and sacrificed after 18 days. Label-free infrared spectral imaging (IRSI) generated high contrast IR images allowing identification of different ECM regions of the skin and the ovarian tumor. IRSI showed a good correlation with collagen distribution as well as organization, as analyzed using second harmonic generation imaging within the tumor area. The results demonstrated that lumican inhibited the growth of ovarian cancer mainly by altering collagen fibrilogenesis.Ovarian cancer remains one of the most fatal cancers due to a lack of robust screening methods of detection at early stages. Extracellular matrix (ECM) mediates interactions between cancer cells and their microenvironment via specific molecules. Lumican, a small leucine-rich proteoglycan (SLRP), maintains ECM integrity and inhibits both melanoma primary tumor development, as well as metastatic spread. The aim of this study was to analyze the effect of lumican on tumor growth of murine ovarian epithelial cancer. C57BL/6 wild type mice (n = 12) and lumican-deficient mice (n = 10) were subcutaneously injected with murine ovarian epithelial carcinoma ID8 cells, and then sacrificed after 18 days. Analysis of tumor volumes demonstrated an inhibitory effect of endogenous lumican on ovarian tumor growth. The ovarian primary tumors were subjected to histological and immunohistochemical staining using anti-lumican, anti-αv integrin, anti-CD31 and anti-cyclin D1 antibodies, and then further examined by label-free infrared spectral imaging (IRSI), second harmonic generation (SHG) and Picrosirius red staining. The IR tissue images allowed for the identification of different ECM tissue regions of the skin and the ovarian tumor. Moreover, IRSI showed a good correlation with αv integrin immunostaining and collagen organization within the tumor. Our results demonstrate that lumican inhibits ovarian cancer growth mainly by altering collagen fibrilogenesis.

Highlights

Ovarian cancer is the gynecological malignancy with the highest case-to-mortality ratio in the western world
We investigated the effect of lumican on Extracellular matrix (ECM) organization and tumor progression in ovarian primary tumors by combining Fourier transform infrared (FTIR) and second harmonic generation (SHG) imaging with conventional histology and immunohistochemistry
Edemas were observed in tumor sections of both groups (Figure 2e,f), but were significantly predominant in Lum−/− mice (Figure 2g, p = 0.02). These differences might be explained by the loss of ECM integrity due to altered collagen fibrilogenesis caused by lumican depletion, resulting in an increased tumor growth [34,40]

Summary

Introduction

Ovarian cancer is the gynecological malignancy with the highest case-to-mortality ratio in the western world. Since ovarian cancer is often asymptomatic, it is generally diagnosed at an advanced stage, giving a poor prognosis [1]. It is the second leading cause of death among patients with gynecologic tumors in the world, as 313,959 women were diagnosed with ovarian cancer, and 207,252 (66%) died of it in 2020 [2]. Novel second line treatments and maintenance therapies (such as PARP inhibitors and anti-angiogenic antibodies) permit an improvement in survival and patient welfare [3]. Due to the rapid proliferation and spread of ovarian cancer within the abdominal cavity and its high rate of intra-abdominal recurrence, the prognosis of patients with this condition is poor. Electronic microscopy permitted a better discrimination of human ovarian cancer cells heterogeneity [5]

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