There is growing evidence that nitric oxide (NO) has an important role in tumor growth. However, information on the expression of NO synthase (NOS) in colorectal cancers is scanty. We therefore investigated the distribution and expression of NOS in human colorectal cancers. The expression of three types of NOS, inducible (iNOS), endothelial (eNOS) and neuronal (nNOS), was examined by immunohistochemistry in 25 cases of colorectal cancer. The expression of iNOS was also investigated at the mRNA level using the reverse transcriptase polymerase chain reaction (RT-PCR) in 6 cases. Correlations were made between iNOS expression and the histopathological findings. Immunoreactive iNOS was detected in the tumor cells in 22 cases (88%) with diffuse cytoplasmic reactions. Expression of iNOS-mRNA detected by RT-PCR in three tumor tissues was over five-fold that in normal mucosa. Intensified immunoreactivity of iNOS was associated with vascular invasion. iNOS expression did not correlate with pathological staging, tumor size, lymph node metastasis, p53 expression or tumor vessel density. Immunoreactive eNOS stained more strongly in the endothelial cells of microvessels within and around the tumor than in the areas remote from the tumor. There is enhanced expression of iNOS and eNOS in human colorectal cancers, which may correlate with tumor growth and vascular invasion.
Abstract. Colorectal cancer is one of the most malignant neoplasms worldwide. Fucoxanthin is a carotenoid present in the chloroplasts of brown seaweeds. In the present study, the anticancer effects of fucoxanthin and its metabolite, fucoxanthinol, on 6 colorectal cancer cell lines and 20 tissue samples from surgically resected clinical colorectal cancer specimens were examined using a collagen-gel droplet embedded culture drug sensitivity test (CD-DST). The in vitro sensitivity to fucoxanthin, fucoxanthinol and the anticancer drugs is expressed as T/C (%), where T is the absorbance of cells which stained by neutral red treated with carotenoids and C is the absorbance of non-staining cells. Fucoxanthin and fucoxanthinol decreased the T/C (%) of Caco-2, WiDr, HCT116, and DLD-1 cell lines at doses of 20 µM. Fucoxanthinol also decreased the T/C (%) of SW620 cells, while the T/C (%) of Colo205 cells was not reduced by treatment with either carotenoid. Specifically, the T/C (%) of Caco-2 and WiDr cells, which were incubated in carotenoid-free medium for 6 days following treatment with 20 µM fucoxanthinol for 24 h, was markedly decreased to 1.4±0.2 and 12.0±0.3%, respectively. Furthermore, fucoxanthin and fucoxanthinol decreased the T/C (%) in colorectal cancer tissue samples. Notably, 20 µM fucoxanthinol treatment resulted in a higher proportion of colorectal cancer samples with a T/C (%) of <50% (13/20, 65%) compared with samples treated with 20 µM fucoxanthin (2/20, 10%). The median T/C (%) value of 35.1% for the 20 cancers specimens treated with 20 µM fucoxanthinol was lower than the median T/C (%) values of 86.3% and 75.8% for those treated with fluorouracil and paclitaxel, respectively. These results suggested that fucoxanthin and fucoxanthinol may be of use as chemotherapeutic agents in colorectal cancer.
To explore the relationships between polyol pathway-related enzymes and pathologic features, we examined the immunohistochemical expression of aldose reductase (AR) and sorbitol dehydrogenase (SDH) in the peripheral nerve and kidney tissues collected postmortem from diabetic patients and compared it with those from non-diabetic patients. Tissue AR protein concentrations were also quantified. In non-diabetic patients, AR distributed in pericytes, smooth muscle cells of endo- and epi-neurial microvessels, Schwann cells in the sciatic nerve, and tubular cells of the renal medulla. By contrast, positive SDH reactions were observed in tubular cells of the renal cortex but were faint in the sciatic nerve. Diabetic patients frequently showed dense AR expressions in the sciatic nerve. In nephropathic diabetic patients, the glomerular mesangial area showed diffuse positive reactions for AR. The severity of structural changes in glomeruli correlated with the intensity of immunoreactive AR (r2=0.626, P<0.01). AR contents in the renal cortex and sciatic nerve from diabetic patients were 1.5- and 1.8-fold greater than those from non-diabetic patients, respectively (P<0.05 for both). These findings are the first to demonstrate enhanced AR expressions in peripheral nerve and renal glomeruli in diabetic patients and its relevance to the characteristic pathology.
To explore the relationships between polyol pathway‐related enzymes and pathologic features, we examined the immunohistochemical expression of aldose reductase (AR) and sorbitol dehydrogenase (SDH) in the peripheral nerve and kidney tissues collected postmortem from diabetic patients and compared it with those from non‐diabetic patients. Tissue AR protein concentrations were also quantified. In non‐diabetic patients, AR distributed in pericytes, smooth muscle cells of endo‐and epi‐neurial microvessels, Schwann cells in the sciatic nerve, and tubular cells of the renal medulla. By contrast, positive SDH reactions were observed in tubular cells of the renal cortex but were faint in the sciatic nerve. Diabetic patients frequently showed dense AR expressions in the sciatic nerve. In nephropathic diabetic patients, the glomerular mesangial area showed diffuse positive reactions for AR. The severity of structural changes in glomeruli correlated with the intensity of immunoreactive AR (r(2)=0.626. P <0.01). AR contents in the renal cortex and sciatic nerve from diabetic patients were 1.5‐ and 1.8‐fold greater than those from non‐diabetic patients, respectively (P <0.05 for both). These findings are the first to demonstrate enhanced AR expressions in peripheral nerve and renal glomeruli in diabetic patients and its relevance to the characteristic pathology.
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