Neo-angiogenesis and the premalignant micro-circulatory augmentation of early colon carcinogenesis

Abstract

Spectroscopic techniques have demonstrated that in the microscopically normal mucosa, there is an increase in mucosal micro-circulation in patients harboring neoplasia elsewhere in the colon (i.e. marker of field carcinogenesis). However, the physiological and molecular basis of this early increase in blood supply (EIBS) has not been elucidated. We, therefore, investigated the microvessel density (MVD) and angiogenic gene expression in the premalignant colonic mucosa from the well-validated azoxymethane (AOM)-treated rat experimental model of colon carcinogenesis. Fisher 344 rats were treated with AOM (15 mg/kg i.p.) or saline and euthanized 14 weeks later (a time-point that precedes carcinoma development). Colon sections were studied for MVD via immunohistochemical assessment for CD31 and location was compared with optical assessment of mucosal hemoglobin with low-coherence enhanced backscattering spectroscopy (LEBS). Finally, we performed a pilot real-time PCR angiogenesis microarray (84 genes) from the microscopically normal colonic mucosa of AOM and age-matched saline treated rats. AOM treatment increased MVD in both the mucosa and submucosa of the rats (125% increase in mucosa; p<0.007, and 96% increase in submucosa; p<0.02) but the increase was most pronounced at the cryptal base consistent with the LEBS data showing maximal hemoglobin augmentation at 200-225μm depth. Microarray analysis showed striking dysregulation of angiogenic and anti-angiogenic factors. We demonstrate, for the first time, that neo-angiogenesis occurs in the microscopically normal colonic mucosa and was accentuated at the bottom of the crypt. This finding has potential implications as a biomarker for risk-stratification and target for chemoprevention.

Inhibitory Activity of Indonesian Soybean in comparison with Soybean Meal on Goblet Cell Count and Micro Vessel Density in Colitis-Associated Mouse Colon Carcinogenesis

“…Previous studies showed that the micro vessel density occurs in the early colon carcinogenesis and was accentuated at the bottom of crypt 46 . MVD is a well-established technique to assess angiogenesis in colon cancer and has prognostic significance 47 .…”

“…MVD is a well-established technique to assess angiogenesis in colon cancer and has prognostic significance 47 . Neo-angiogenesis have potential implications as a target for chemoprevention 25, 46 .…”

Hemoglobin parameters from diffuse reflectance data

“…To quantify this result, we tested the hypothesis that the average hemoglobin concentration measured with a pressure <112 mN∕mm 2 was greater than the average hemoglobin concentration measured with a pressure >112 mN∕mm 2 . A T-test shows that the hypothosis is correct (α ¼ 0.01).…”

“…1 Vascular changes occur quite early in the disease progression leading to colon cancer based on a study of a well-established model system. 2 In oral tissue, microvessel density is reported to increase as pathology changes from normal to dysplastic to squamous cell carcinoma. 3,4 For breast cancer, some studies have demonstrated a correlation between angiogenesis (microvessel density) and clinicopathologic parameters, although there are discrepancies in results, some of which likely arise as a consequence of the variety of techniques (e.g., immunohistochemistry and visual microscopy) used to assess angiogenesis and microvessel density.…”

Algorithm for automated selection of application-specific fiber-optic reflectance probes

“…Our optical and histological investigations in human patients and animal models of colon carcinogenesis have shown diagnostic alterations in hemoglobin concentration that are present in the mucosa but attenuated at deeper submucosal depths. [1][2][3][4][5] Studies with angle-resolved low-coherence interferometry demonstrate that elevation of nuclear diameter associated with dysplasia in Barrett's esophagus was only detectable at a depth of 200 to 300 μm and not observable at 0 to 100 μm or 100 to 200 μm. 6 Several fiber-optic probe modalities have been developed to target the mucosal layer with a wide field of view.…”