Kallikrein-related peptidase 7 (KLK7) is a proliferative factor that is aberrantly expressed in human colon cancer.

Emerging evidence indicates that serine proteases of the tissue kallikrein-related peptidases family (KLK) are implicated in tumorigenesis. We recently reported the ectopic expression of KLK4 and KLK14 in colonic cancers and their signaling to control cell proliferation. Human tissue kallikrein-related peptidase 7 (KLK7) is often dysregulated in many cancers; however, its role in colon tumorigenesis has not yet been established. In the present study, we analyzed expression of KLK7 in 15 colon cancer cell lines and in 38 human colonic tumors. In many human colon cancer cells, KLK7 mRNA was observed, which leads to KLK7 protein expression and secretion. Furthermore, KLK7 was detected in human colon adenocarcinomas, but it was absent in normal epithelia. KLK7 overexpression in HT29 colon cancer cells upon stable transfection with a KLK7 expression plasmid resulted in increased cell proliferation. Moreover, subcutaneous inoculation of transfected cells into nude mice led to increased tumor growth that was associated with increased tumor cell proliferation as reflected by a positive Ki-67 staining. Our results demonstrate the aberrant expression of KLK7 in colon cancer cells and tissues and its involvement in cell proliferation in vitro and in vivo. Thus, KLK7 may represent a potential therapeutic target for human colon tumorigenesis.

Novel DOTA-neurotensin analogues for 111In scintigraphy and 68Ga PET imaging of neurotensin receptor-positive tumors.

Overexpression of the high affinity neurotensin receptor 1 (NTSR1), demonstrated in several human cancers, has been proposed as a new marker for human ductal pancreatic carcinoma and as an independent factor for poor prognosis for ductal breast cancer, head and neck squamous cell carcinoma, and non-small cell lung cancer. The aim of the present study was to develop new DOTA-neurotensin analogues for positron emission tomography (PET) imaging with (68)Ga and for targeted radiotherapy with (90)Y or (177)Lu. We synthesized a DOTA-neurotensin analogue series. Two of these peptides bear two sequence modifications for metabolic stability: DOTA-NT-20.3 shares the same peptide sequence as the previously described DTPA-NT-20.3. In the sequence of DOTA-NT-20.4, the Arg(8)-Arg(9) bond was N-methylated instead of the Pro(7)-Arg(8) bond in DOTA-NT-20.3. An additional sequence modification was introduced in DOTA-LB119 to increase stability. A spacer was added between DOTA and the peptide sequence to increase affinity. Binding to HT29 cells, which express NTSR1, in vivo stability, and biodistribution of the various analogues were compared, and the best candidate was used to image tumors of various sizes with the microPET in mice. (111)In-DOTA-NT-20.3, in spite of a relatively high uptake in kidneys, showed specific tumor uptake and elevated tumor to other organ uptake ratios. High contrast images were obtained at early time points after injection that allowed tumor detection at a time interval postinjection appropriate for imaging with the short-lived radionuclide (68)Ga. (111)In-DOTA-NT-20.4 displayed inferior binding to HT29 cells and reduced tumor uptake. (111)In-DOTA-LB119 displayed at early time points a significantly lower renal uptake but also a lower tumor uptake than (111)In-DOTA-NT-20.3, although binding to HT29 cells was similar. (68)Ga-DOTA-NT-20.3 displayed higher tumor uptake than (68)Ga-DOTA-LB119 and allowed the detection of very small tumors by PET. In conclusion, DOTA-NT-20.3 is a promising candidate for (68)Ga-PET imaging of neurotensin receptor-positive tumors. DOTA-NT-20.3 may also be considered for therapy, as the yttrium-labeled peptide has higher affinity than that of the indium-labeled one. A prerequisite for therapeutic application of this neurotensin analogue would be to lower kidney uptake, for example, by infusion of basic amino acids, gelofusin, or albumin fragments, to prevent nephrotoxicity, as with radiolabeled somatostatin analogues.

Pseudomonas fluorescens alters the intestinal barrier function by modulating IL-1ß expression through hematopoietic NOD2 signaling.

BACKGROUND: Ileal Crohn's disease is related to NOD2 mutations and to a gut barrier dysfunction. Pseudomonas fluorescens has also been associated with ileal Crohn's disease. The aim of this study was to determine the impact of P. fluorescens on the paracellular permeability in ileum and Peyer's patches. METHODS: To explore this question, in vivo and ex vivo experiments were performed in wild-type, Nod2, Nod2, and IL-1R mice together with in vitro analyses using the Caco-2 (epithelial) and the THP-1 (monocyte) human cell lines. RESULTS: Pseudomonas fluorescens increased the paracellular permeability of the intestinal mucosa through the secretion of IL-1ß by the immune cell populations and the activation of myosin light chain kinase in the epithelial cells. Induction of the IL-1ß pathway required the expression of Nod2 in the hematopoietic compartment, and muramyl dipeptide (a Nod2 ligand) had an inhibitory effect. CONCLUSIONS: Pseudomonas fluorescens thus alters the homeostasis of the epithelial barrier function by a mechanism similar to that previously observed for Yersinia pseudotuberculosis. This work further documents a putative role of psychrotrophic bacteria in Crohn's disease.