Background and purpose: Perivascular adipose tissue (PVAT) attenuates vascular contraction, but the mechanisms remain largely unknown. The possible involvement of endothelium (E) and hydrogen peroxide (H 2 O 2 ) was investigated. Experimental approach: Aortic rings from Wistar rats were prepared with both PVAT and E intact (PVAT þ E þ ), with either PVAT or E removed (PVAT-E þ , or PVAT þ E-), or with both removed (PVAT-E-) for functional studies. Nitric oxide (NO) production was measured. Key results: Contraction to phenylephrine and 5-HT respectively was highest in PVAT-E-, lowest in PVAT þ E þ , and intermediate in PVAT þ E-or PVAT-E þ . In bioassay experiments, transferring bathing solution incubated with a PVAT þ ring (donor) to a PVAT-ring (recipient) induced relaxation in the recipient. This relaxation was abolished by E removal, NO synthase inhibition, scavenging of NO, high extracellular K þ , or blockade of calcium-dependent K þ channels (K Ca ). The solution stimulated NO production in isolated endothelial cells and in PVAT-E þ rings. In E-rings, the contraction to phenylephrine of PVAT þ rings but not PVAT-rings was enhanced by catalase or soluble guanylyl cyclase (sGC) inhibitor, but reduced by superoxide dismutase and tiron. In PVAT-E-rings, H 2 O 2 attenuated phenylephrine-induced contraction. This effect was counteracted by sGC inhibition. NO donor and H 2 O 2 exhibited additive inhibition of the contraction to phenylephrine in PVAT-E-rings. Conclusion: PVAT exerts its anti-contractile effects through two distinct mechanisms: (1) by releasing a transferable relaxing factor which induces endothelium-dependent relaxation through NO release and subsequent K Ca channel activation, and (2) by an endothelium-independent mechanism involving H 2 O 2 and subsequent activation of sGC.

These results show that PVAT enhances the arterial contractile response to perivascular nerve stimulation through the production of superoxide mediated by NAD(P)H oxidase, and that this enhancement involves activation of tyrosine kinase and MAPK/ERK pathway.

Abstract. The ability to penetrate the dermal basement membrane and subsequently proliferate in the underlying mesenchyme is one of the key steps in malignant progression of human melanomas. We previously undertook studies aimed at assessing how normal dermal fibroblasts (one of the main cellular components of mesenchyme) may affect the growth of human melanoma cells and facilitate the overgrowth of malignant subpopulations (Comil, I., D. Theodorescu, S. Man, M. Herlyn, J. Jambrosic, and R. S. Kerbel. 1991. Proc. Natl. Acad. Sci. USA. 88:6028-6032). We found that melanoma cell lines from early-stage (metastatically incompetent) lesions were growth inhibited whereas those from advanced-stage (metastatically competent) lesions were stimulated under the same conditions by co-culture with fibroblasts; conditioned medium from such cells gave the same result.

Recently we reported that human dermal fibroblasts, or conditioned media obtained from such cells, affect the growth of human melanoma cells as a direct function of tumor progression: melanoma cells obtained from earlystage (metastatically incompetent) primary lesions were growth inhibited, whereas cells obtained from more advanced (metastaticaly competent) primary lesions, or metastases, were growth stimulated. Ion-exchange and gel-filtration chromatography of fibroblast conditioned medium revealed the inhibitor to be a protein of molecular mass between 20 and 30 kDa and distinct from the stimulator. This is the approximate molecular mass of interleukin 6 (IL-6), a ubiquitous multifunctional cytokine known to affect in particular many kinds of hemopoietic and lymphoid cells. Since this cytokine is known to be made by fibroblasts, we attempted to determine if the human fibroblast-derived growth inhibitor (hFDGI) was identical to IL-6. Neutralizing antibodies specific for IL-6 completely eliminated the inhibitory activity ofhFDGI. Moreover, exposure to human recombinant IL-6 was found to inhibit the growth of earlystage melanoma cells obtained from radial growth phase (RGP) or early vertical growth phase (VGP) primary lesions in three of four cases. In contrast, melanoma cells from a number of more advanced VGP primary lesions, or from distant metastases, were completely resistant to this IL-6-mediated growth inhibition. Acquisition of an "IL-6-resistant" phenotype by metastatically competent melanoma cell variants may provide such cells with a proliferative advantage within the dermal mesenchyme (a hallmark of melanoma cells that are malignant), helping them eventually to dominate advanced primary lesions and to establish secondary growths elsewhere.The growth and spread of cancers can be strongly influenced by surrounding normal tissues in a variety of ways. Tumor angiogenesis-i.e., the process satisfying the absolute requirement of new blood vessel capillaries for solid tumors to grow beyond 1-2 mm in diameter-is perhaps the most striking illustration of this interaction (1). Similarly, a variety of different hormones or locally produced growth factors and cytokines secreted by various normal cells can stimulate tumor growth (2, 3). In addition to stimulating the growth of tumors, surrounding normal cells can, in other circumstances, significantly suppress such growth (4); this is especially evident in the case of an interspersed minority subpopulation of tumor cells surrounded by an excess of normal cells, such as fibroblasts (5).With few exceptions the effects of a given normal cell population on the growth and behavior of a particular type of tumor have not been studied in the context of different stages of tumor progression. It is possible, for example, that the effect of normal adjacent cells on the growth of tumor cells from primary lesions early in tumor progression is quite different from the effects of more advanced (metastatically competent) primary lesions, or metastases. We recently uncover...

Ang-(1-7) released by PVAT acts on the endothelium to cause the release of nitric oxide, and nitric oxide acts as a hyperpolarizing factor through K(Ca) channels to cause relaxation of the blood vessel.

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The expression levels of miR-365 vary in different malignancies. Herein, we found that miR-365 was overexpressed in both cells and clinical specimens of cutaneous squamous cell carcinoma (SCC). We demonstrated that the HaCaTpre-miR-365-2 cell line, which overexpressed miR-365, could induce subcutaneous tumors in vivo. Antagomir-365, an anti-miR-365 oligonucleotide, inhibited cutaneous tumor formation in vivo, along with G1 phase arrest and apoptosis of cancer cells. These findings suggest that miR-365 may act as an onco-miR in cutaneous SCC both in vitro and in vivo. The present study provides valuable insight into the role of miR-365 in cutaneous SCC formation, which can help develop new drug and miR-365 target-based therapies for cutaneous SCC.

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