Takahiro Umemoto

Cloning and pharmacological characterization of a novel gene encoding human nucleoside transporter 1 (hNT1) from a human breast cancer cDNA library

AIMS We isolated a novel gene encoding human nucleoside transporter 1 (hNT1), from a human breast cancer cDNA library. MAIN METHODS A nondirectional cDNA library was screened by an EST clone (GenBanktrade mark/EMBL/DDBJ: BU944345). A Xenopus laevis oocyte expression system was used for functional characterization. Membrane localization in the human breast was determined by immunohistochemistry. KEY FINDINGS Isolated hNT1 cDNA consisted of 246 base pairs that encoded an 82-amino acid protein. By RT-PCR analysis, hNT1 mRNA was strongly detected in the breast cancer tissues. When expressed in X. oocytes, hNT1 mediated the high affinity transport of [(3)H]5-fluorouracil (5-FU) with a K(m) value of 69.2+/-24.5 nM in time- and pH-dependent, and Na(+)-independent manners. A cis-inhibition experiment revealed that hNT1 mediated transport of [(3)H]5-FU is strongly inhibited by various nucleosides such as pyrimidine, uracil, uridine, guanosine, inosine, thymidine, adenosine, cytidine and purine suggesting that hNT1 may be involved in the trans epithelial transport of these endogenous substrates. Immunohistochemical analysis revealed that the hNT1 protein is localized in the lactiferous duct epithelium. SIGNIFICANCE Our present results indicate that a newly isolated cDNA clone, hNT1, is a key molecule for the breast handling of 5-FU in humans.

Gastric mixed adenoneuroendocrine carcinoma occurring 50 years after a gastroenterostomy with braun anastomosis.

A 75-year-old man was diagnosed with gastric cancer. Fifty years previously, he had undergone gastroenterostomy with a Braun enteroenterostomy. At present, a distal gastrectomy and small intestinal partial resection were performed. Intraoperatively, the tumor was localized to the previous stomal site. HE staining showed that the tumor comprised two elements: a tubular adenocarcinoma on the gastric side and a neuroendocrine carcinoma (NEC) on the jejunal side. The final pathologic diagnosis was mixed adenoneuroendocrine carcinoma based on an immunohistochemical analysis of endocrine markers and an elevated Ki-67 labeling index. The risk of later cancer development cancer recurrence near the gastrojejunostomy site is well known. Potentially, chronic enterogastric bile reflux may irritate the gastric mucosa and act as a promoter. Gastric NEC has a strong malignant potential. We suspect that, in the present case, the constant exposure to secondary bile may have induced a gastric mucosal adenocarcinoma, which finally differentiated into a NEC.

Activation of Cyclosporin A Transport by a Novel λ Light Chain of Human Ig Surface Antigen-Related Gene in Xenopus laevis Oocytes

In the present study, we isolated and determined the pharmacological characteristics of a novel gene encoding the λ light chain of human Ig surface antigen-related gene (IgLC-rG). The isolated cDNA consisted of 693 base pairs that encoded a 232-amino acid protein. Northern blot analysis revealed that the IgLC-rG mRNA is expressed in the adult spleen and small intestine but not in fetal tissues. When expressed in Xenopus laevis oocytes, IgLC-rG mediated the high-affinity transport of [3H]cyclosporin A (CsA) (Km = 189.7 ± 123.5 nM) in a sodium-dependent manner; however, other organic solutes such as p-aminohippuric acid and TEA were not transported via IgLC-rG. The transport of [3H]CsA by IgLC-rG was sensitive to pH. The uptake of [3H]CsA was trans-stimulated by CsA and GSH. Immunohistochemical analysis revealed that the IgLC-rG protein is localized at the brush border membrane in the human small intestine. Although the isolated IgLC-rG gene is a member of the human Ig λ light chain surface antigen superfamily, our findings suggest that IgLC-rG functions as a novel transport peptide responsible for CsA in the human body. Our results should provide insight into the novel function of membrane-bound proteins, such as Igs.

The impact of stromal Hic-5 on the tumorigenesis of colorectal cancer through lysyl oxidase induction and stromal remodeling

Carcinoma-associated fibroblasts (CAFs) influence tumor initiation, progression, and metastasis within the tumor-associated stroma. This suggests that CAFs would be a potential target for tumor therapy. Here we found that Hydrogen peroxide-inducible clone-5 (Hic-5), also named transforming growth factor beta-1-induced transcript 1 protein (Tgfb1i1), was strongly induced in CAFs found in human colorectal cancer. To investigate the role of Hic-5 in CAFs, we isolated CAFs and the control counterpart normal fibroblasts (NFs) from human colorectal cancer and non-cancerous regions, respectively. Hic-5 was highly expressed in isolated human CAFs and strongly induced in NFs in culture by the supernatant from cultured colorectal cancer cells as well as cytokines such as TGF-β, IL-1β and stromal cell-derived factor 1 (SDF-1/CXCL12). Furthermore, tumor growth was inhibited in a co-culture assay with Hic-5 knockdown fibroblasts compared with control fibroblasts. To clarify the function and significance of Hic-5 in colorectal cancer in vivo, we utilized a mouse model of azoxymethane (AOM)-induced colorectal cancer using Hic-5-deficient mice. Lack of Hic-5 in CAFs completely prevented AOM-induced colorectal cancer development in the colon tissues of mice. Mechanistic investigation revealed that Hic-5 promoted the expression of lysyl oxidase and collagen I in human control counterpart fibroblasts. Taken together, these results demonstrate that Hic-5 in CAFs is responsible for orchestrating or generating a tumor-promoting stroma.

Toward standardized patient positioning to avoid peripheral nerve injury during laparoscopic colorectal surgery: Application of a protocol and study of the resulting relationship between total rotation time and contact pressure at the shoulder: Contact pressure during LAC

Generally, laparoscopic colorectal surgery is performed with the patient in the lithotomy and rotated positions. The lithotomy position, however, is associated with intraoperative peripheral nerve injury (IPNI). We studied the relationship between patient positioning during laparoscopic colorectal surgery, contact pressure at the shoulder, and the occurrence of IPNI and tested a positioning protocol aimed at surgical safety in addition to maintenance of a good surgical field.