Modulation of RTK by sEcad: a putative mechanism for oncogenicity in oropharyngeal SCCs.

OBJECTIVE: Heightened levels of sEcad are found in the serum of patients with cancer and correlate with an unfavorable prognosis and later-stages of disease. In this study, we explored whether sEcad is elevated in human OPSCC specimens and FaDu cells. Additionally, we investigated sEcad-EGFR and sEcad-IGF-1R interactions and performed a functional analysis of sEcad in OPSCC cancers. MATERIALS AND METHODS: sEcad, EGFR, and IGF-1R levels were examined in human OPSCC specimens and cells by immunoblotting. sEcad-EGFR and sEcad-IGF-1R interactions were examined by immunoprecipitation and immunoblot assays. Levels of sEcad on EGFR and IGF-1R pathway components were evaluated by IB. The effects of sEcad on OPSCC proliferation, migration, and invasion were assessed using standard cellular assays. RESULTS: Statistical analysis demonstrated that sEcad levels were significantly higher in OPSCC primary tumors and cells compared with normal controls. IP studies indicated that sEcad associated with EGFR and IGF-1R, and addition of sEcad resulted in a statistically significant increase in downstream signaling. Finally, cell-based assays demonstrated enhanced sEcad-induced proliferation, migration, and invasion, which was blocked by EGFR and IGF-1R inhibitors. CONCLUSIONS: These findings suggest that sEcad may play an important role in OPSCC oncogenicity via its interaction and activation of EGFR and IGF-1R.

Soluble E-cadherin: a critical oncogene modulating receptor tyrosine kinases, MAPK and PI3K/Akt/mTOR signaling.

E-cadherin, a cell-cell adhesion glycoprotein, is frequently downregulated with tumorigenic progression. The extracellular domain of E-cadherin is cleaved by proteases to generate a soluble ectodomain fragment, termed sEcad, which is elevated in the urine or serum of cancer patients. In this study, we explored the functional role of sEcad in the progression of skin squamous cell carcinomas (SCCs). We found that full-length E-cadherin expression was decreased and sEcad increased in human clinical tumor samples as well as in ultraviolet (UV)-induced SCCs in mice. Interestingly, sEcad associated with members of the human epidermal growth factor receptor (HER) and insulin-like growth factor-1 (IGF-1R) family of receptors in human and UV-induced mouse tumors. Moreover, in both E-cadherin-positive (E-cadherin(+)) and -negative (E-cadherin(-)) cells in vitro, sEcad activated downstream mitogen-activated protein (MAP) kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling and enhanced tumor growth, motility and invasion, the latter via activation of matrix metalloproteinase-2 (MMP-2) and MMP-9. To this end, HER, PI3K or MEK inhibitors suppressed sEcad's tumorigenic effects, including proliferation, migration and invasion. Taken together, our data suggest that sEcad contributes to skin carcinogenesis via association with the HER/IGF-1R-family of receptors and subsequent activation of the MAPK and PI3K/Akt/mTOR pathways, thereby implicating sEcad as a putative therapeutic target in cutaneous SCCs.

IL-1beta inhibits TGFbeta in the temporomandibular joint.

Similarly to humans, healthy, wild-type mice develop osteoarthritis, including of the temporomandibular joint (TMJ), as a result of aging. Pro-inflammatory cytokines, such as IL-1beta, IL-6, and TNFalpha, are known to contribute to the development of osteoarthritis, whereas TGFbeta has been associated with articular regeneration. We hypothesized that a balance between IL-1beta and TGFbeta underlies the development of TMJ osteoarthritis, whereby IL-1beta signaling down-regulates TGFbeta expression as part of disease pathology. Our studies in wild-type mice, as well as the Col1-IL1beta(XAT) mouse model of osteoarthritis, demonstrated an inverse correlation between IL-1beta and TGFbeta expression in the TMJ. IL-1beta etiologically correlated with joint pathology, whereas TGFbeta expression associated with IL-1beta down-regulation and improvement of articular pathology. Better understanding of the underlying inflammatory processes during disease will potentially enable us to harness inflammation for orofacial tissue regeneration.

Strain differences in the expression of corticotropin-releasing hormone immunoreactivity in nerves that supply the spleen and thymus.

The existence of nerve fibers containing corticotropin-releasing hormone (CRH) immunoreactivity in primary and secondary lymphoid organs from three strains of young adult male rats was examined. Spleens and thymuses from Fischer 344 (F344), Sprague-Dawley (SD) and Lewis (LEW) rats were prepared for immunocytochemistry using antisera directed against CRH. In F344 and SD rats, we were unable to demonstrate CRH-immunoreactive nerves in either the thymus or the spleen. Despite the lack of CRH-containing nerves, CRH immunoreactivity was present in pleotropic cells in the septum, cortex and medulla of the thymus, and in the red and white pulp of spleens from F344 and SD rats. In contrast, CRH+ nerves were found in thymuses and spleens from LEW rats. CRH+ nerves coursed in the interlobular septa, capsule, cortex and medulla of the LEW rat thymus. Large CRH-immunoreactive nerve bundles were present in the hilar region of the LEW rat spleen, and individual CRH+ fibers coursed in the capsule, trabeculae, red pulp, venous sinuses and marginal zone of the white pulp of the spleen. These findings indicate strain differences in neurotransmitter-specific nerves that innervate the rat spleen and thymus under basal conditions.

Localization of corticotropin-releasing factor in primary and secondary lymphoid organs of the rat.

Cells of the immune system produce a variety of neuropeptides or peptide hormones, either constitutively or upon induction, and possess specific neuropeptide receptors that display ligand-receptor interactions similar to those described in the central nervous system (CNS). These findings suggest that specific subsets of lymphoid cells can produce and respond to peptides previously thought to be principally neural mediators. Recently, corticotropin releasing factor (CRF) mRNA was detected in the rat thymus and spleen, although the cells that synthesize CRF were not identified. We examined the localization of CRF and its mRNA in the rat spleen, thymus, and mesenteric lymph nodes using immunocytochemistry (ICC) and in situ hybridization (ISH), respectively. Immunoreactive CRF was present in cells in the marginal zone and red pulp of the spleen, in connective tissue septa and the subcapsular region of the thymus, and in the medullary cords and sinuses of the mesenteric lymph nodes. Dual ICC/ISH for CRF and its mRNA, respectively, demonstrated CRF mRNA over CRF-immunoreactive cells, suggesting CRF synthesis. Double-label ICC for CRF and markers for specific immunocyte subsets suggest that CRF+ cells in the spleen and thymus are macrophages. CRF+ cells in primary and secondary lymphoid organs reside in compartments that are innervated by sympathetic nerves, and some cells appears to be contacted by noradrenergic sympathetic nerve fibers, suggesting that CRF release may be influenced by the sympathetic nervous system, as it is in the hypothalamo-pituitary-adrenal axis. The presence of CRF in organs of the immune system suggests that this neuropeptide may modulate immune functions after paracrine release.