Altered organization of collagen fibers in the uninvolved human colon mucosa 10 cm and 20 cm away from the malignant tumor

Abstract

Remodelling of collagen fibers has been described during every phase of cancer genesis and progression. Changes in morphology and organization of collagen fibers contribute to the formation of microenvironment that favors cancer progression and development of metastasis. However, there are only few data about remodelling of collagen fibers in healthy looking mucosa distant from the cancer. Using SHG imaging, electron microscopy and specialized softwares (CT-FIRE, CurveAlign and FiberFit), we objectively visualized and quantified changes in morphology and organization of collagen fibers and investigated possible causes of collagen remodelling (change in syntheses, degradation and collagen cross-linking) in the colon mucosa 10 cm and 20 cm away from the cancer in comparison with healthy mucosa. We showed that in the lamina propria this far from the colon cancer, there were changes in collagen architecture (width, straightness, alignment of collagen fibers and collagen molecules inside fibers), increased representation of myofibroblasts and increase expression of collagen-remodelling enzymes (LOX and MMP2). Thus, the changes in organization of collagen fibers, which were already described in the cancer microenvironment, also exist in the mucosa far from the cancer, but smaller in magnitude. Extracellular matrix (ECM) is no longer considered as an inert substrate, a three-dimensional network which only "fills the spaces" between cells and provide mechanical support 1,2. Today, ECM is known to be a complex and dynamic structure, whose chemical and biophysical properties affect cell adhesion 3 , proliferation 4 morphology 5 , migration 6 , regulate tissue morphogenesis 7,8 and fluid volume in tissues 9. The most abundant component of ECM in the lamina propria of the colon mucosa is type I collagen. Remodelling of collagen fibers has been described in almost every solid cancer, including colorectal cancer. During tumor formation and progression, collagen remodelling is constantly carried out: degradation, synthesis, cross-linking of fibers, change of fiber orientation, and interaction of cells of the innate and acquired immune system with collagen fibers 10,11. Changes in morphology, representation, and organization of collagen fibers contribute to the formation of the microenvironment that favors tumor progression, primarily through its effect on cell migration and polarization 12. Also, remodelling of collagen fibers on premetastatic sites is of great importance in determination of survival and growth of disseminated cancer cells, and thus, formation of metastasis 13,14. Remodelling of collagen fibers may be a result of changes in synthesis, degradation or cross-linking. Main cells responsible for synthesis of collagen in colon mucosa are fibroblasts and myofibroblasts. The most important enzymes for degradation of collagen fibers are matrix metalloproteinases (MMPs). It has been shown that expression of MMP2 and MMP9 is increased in colorectal cancer and influences its progression and

Polarization‐dependent second‐harmonic generation for collagen‐based differentiation of breast cancer samples

“…Samples that present more organized collagen structures lead to the increment of B values 40, 41 . This trend is also observed in studies, where anisotropy coefficient β is calculated and measured 42 . Angle δ in Equation 2 corresponds to the angle between laser's propagation and fiber's axes.…”

“…It has to be noted that in the experimental design of the current work, a forward detection scheme was employed for the collection of the SHG images from thin paraffin‐embedded sections. Although SHG anisotropy parameter values depend on the detection geometry, 49 the extracted information could be useful as a novel diagnostic tool for a quick characterization of newly excised thin biopsy samples.. A recent study using PSHG reflection measurements at colon mucosa samples shows that cancer may increase collagen fibrils organization even 20 cm away from cancerous area 42 …”

The Macro- and Micro-Mechanics of the Colon and Rectum I: Experimental Evidence

“…Second-harmonic generation (SHG) microscopy has emerged as a powerful method for imaging collagen fibers with submicron resolution in a diverse range of tissues, which is highly selective to the collagen fibril/fiber structure and can visualize collagen fibers several hundred microns deep into the tissue using excitation light at infra-red range (800–1200 nm). SHG imaging on large intestinal tissues was reported by several recent studies in the literature [ 75 , 76 , 77 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 ]. Compared with conventional staining methods on thin tissue slides of ~10 microns thick, we recently reported that SHG microscopy can visualize collagen fibers through the thickness of an intact mouse colon (~200 microns thick) and most of the rectum (300–400 microns) [ 46 ].…”

“…In addition, malignant tumor is reported to alter the organization of collagen fibers in the colonic mucosa even 10 cm to 20 cm away from its location. This tumor causes an increase in collagen fiber thickness which correlates with the formation of invadopodia, i.e., specialized cell structures that increase the migratory capacity of cancer cells [ 85 ]. In contrast, changes in collagen contents in intestinal layers other than the mucosa are rarely reported.…”

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

“…Even with a diverse and small cohort of carcinoma samples, it is not surprising that fiber width is different between these and non-malignant samples as we previously showed that collagen fiber width can predict poor outcome in canine mammary tumor patients, even when used in multivariate analysis taking clinical parameters into account. Increased collagen fiber width in the peritumor stroma in human colonic cancer 95 and in the stroma immediately surrounding neoplastic epithelium of pancreatic ductal adenocarcinoma samples was also recognized to favor cancer progression 96 and increased intratumoral collagen width was a powerful predictor of poor outcome in human gastric cancer 97 . The increased fiber width has been shown to correlate with change in cancer cell shape, formation of invadopodia and increased migration 98 , 99 and has recently been shown to mechanically activate myofibroblasts 100 .…”