Proteomic signatures of the desmoplastic invasion front reveal collagen type XII as a marker of myofibroblastic differentiation during colorectal cancer metastasis.

Cancer-associated fibroblasts (CAFs), represent a pivotal compartment of solid cancers (desmoplasia), and are causatively implicated in cancer development and progression. CAFs are recruited by growth factors secreted by cancer cells and they present a myofibroblastic phenotype, similar to the one obtained by resident fibroblasts during wound healing. Paracrine signaling between cancer cells and CAFs results in a unique protein expression profile in areas of desmoplastic reaction, which is speculated to drive metastasis. In an attempt to decipher large-scale proteomic profiles of the cancer invasive margins, we developed an in vitro coculture model system, based on tumor-host cell interactions between colon cancer cells and CAFs. Proteomic analysis of conditioned media derived from these cocultures coupled to mass spectrometry and bioinformatic analysis was performed to uncover myofibroblastic signatures of the cancer invasion front. Our analysis resulted in the identification and generation of a desmoplastic protein dataset (DPD), consisting of 152 candidate proteins of desmoplasia. By using monoculture exclusion datasets, a secretome algorithm and gene-expression meta-analysis in DPD, we specified a 22-protein "myofibroblastic signature" with putative importance in the regulation of colorectal cancer metastasis. Of these proteins, we investigated collagen type XII by immunohistochemistry, a fibril-associated collagen with interrupted triple helices (FACIT), whose expression has not been reported in desmoplastic lesions in any type of cancer. Collagen type XII was highly expressed in desmoplastic stroma by and around alpha-smooth muscle actin (α-SMA) positive CAFs, as well as in cancer cells lining the invasion front, in a small cohort of colon cancer patients. Other stromal markers, such as collagen type III, were also expressed in stromal collagen, but not in cancer cells. In a complementary fashion, gene expression meta-analysis revealed that COL12A1 is also an upregulated gene in colorectal cancer. Our proteomic analysis identified previously documented markers of tumor invasion fronts and our DPD could serve as a pool for future investigation of the tumor microenvironment. Collagen type XII is a novel candidate marker of myofibroblasts, and/or cancer cells undergoing dedifferentiation.

Early peri-implant tissue reactions on different titanium surface topographies.

OBJECTIVES: The purpose of the present study was to investigate the early peri-implant soft tissue healing on different titanium surface topographies. MATERIAL AND METHODS: Titanium implants with smooth or rough surfaces were placed in the extraction site at 1 month after the maxillary first molar extractions of 15 male Sprague-Dawley rats. At 4 and 7 days after implant surgery, the peri-implant oral mucosa was randomly harvested and analyzed for collagen fiber orientation, and expression of extracellular matrix genes. Descriptive and paired t-tests were performed where appropriate (α = 0.05). RESULTS: The laser scanning microscopic analysis of the Sirius red stained peri-implant connective tissue revealed a parallel and uniform collagen fiber orientation along the smooth implant at both 4 and 7 days. In contrast, the collagen fibers of the comparative peri-implant tissue from rough surface implants at 7 days were not arranged in parallel orientation but in an irregular a "cotton-ball-like." The levels of mRNA of types III and XII collagen and transforming growth factor-ß1 significantly increased in the smooth implant group compared with the rough implant group at both 4 and 7 days or either one of days. CONCLUSION: The results of this study suggest that implant surface characteristics may affect early events of soft tissue healing by influencing collagen fiber orientation and expression of key genes for initial healing.

Characteristic changes of periodontal ligament-derived cells during passage.

BACKGROUND AND OBJECTIVE: Although periodontal ligament-derived cells are expected to be a useful source of cells for periodontal tissue engineering, the characteristic changes of primary cultured cells have not been well studied. Therefore, the aim of this study was to investigate the characteristics of periodontal ligament-derived cells and their changes during passage. MATERIAL AND METHODS: Human periodontal ligament tissue was obtained from extracted third molars. Cells were subcultured until passage 6 and the cell characteristics from early to late passages were evaluated using immunofluorescence microscopy, alkaline phosphatase activity analyses, reverse transcription-polymerase chain reaction and quantitative real-time polymerase chain reaction. To examine the function of periodontal ligament-derived cells further, cells were transplanted into the renal subcapsule of an immunocompromised rat. RESULTS: Immunofluorescence results showed relatively uniform expression of MSX-2 and osteonectin from passage 1 until passage 6. The STRO-1-positive fraction was 33.5% at passage 0, which was reduced to 14.7% at passage 3. Cultured cells at passage 1 expressed mRNA for collagen type I, collagen type XII, Runx2, alkaline phosphatase, osteonectin, osteopontin, scleraxis, tenomodulin, Msx2, GDF5 and GDF7 genes, but not for bone sialoprotein. The level of mRNA expression from tenomodulin and collagen type XII genes decreased after passage 3. Alkaline phosphatase activity decreased in cells at later passages. Osteogenic induction of periodontal ligament-derived cells resulted in a down-regulation of the tenomodulin gene. Transplanted cells from both early and late passages produced dense collagen fiber bundles without calcified tissue. CONCLUSION: Cultured periodontal ligament-derived cells were a morphologically homogeneous population, although expression of STRO-1 was limited in primary culture. Cultured cells showed de-differentiation during passage for both osteogenesis- and tendo/ligamentogenesis-related genes.