Intermittent intense ultraviolet (UV) exposure represents an important aetiological factor in the development of malignant melanoma. The ability of UV radiation to cause tumour-initiating DNA mutations in melanocytes is now firmly established, but how the microenvironmental effects of UV radiation influence melanoma pathogenesis is not fully understood. Here we report that repetitive UV exposure of primary cutaneous melanomas in a genetically engineered mouse model promotes metastatic progression, independent of its tumour-initiating effects. UV irradiation enhanced the expansion of tumour cells along abluminal blood vessel surfaces and increased the number of lung metastases. This effect depended on the recruitment and activation of neutrophils, initiated by the release of high mobility group box 1 (HMGB1) from UV-damaged epidermal keratinocytes and driven by Toll-like receptor 4 (TLR4). The UV-induced neutrophilic inflammatory response stimulated angiogenesis and promoted the ability of melanoma cells to migrate towards endothelial cells and use selective motility cues on their surfaces. Our results not only reveal how UV irradiation of epidermal keratinocytes is sensed by the innate immune system, but also show that the resulting inflammatory response catalyses reciprocal melanoma-endothelial cell interactions leading to perivascular invasion, a phenomenon originally described as angiotropism in human melanomas by histopathologists. Angiotropism represents a hitherto underappreciated mechanism of metastasis that also increases the likelihood of intravasation and haematogenous dissemination. Consistent with our findings, ulcerated primary human melanomas with abundant neutrophils and reactive angiogenesis frequently show angiotropism and a high risk for metastases. Our work indicates that targeting the inflammation-induced phenotypic plasticity of melanoma cells and their association with endothelial cells represent rational strategies to specifically interfere with metastatic progression.

We assessed the presence of hepatitis B virus (HBV) DNA in liver or serum samples from 134 patients with hepatitis B surface antigen (HBsAg)-negative chronic liver disease, including 20 with hepatocellular carcinoma. HBV DNA sequences were detected in 52 of the 88 liver samples (59 per cent), including 17 of the 20 samples from patients with hepatocellular carcinoma. Presumably "replicative forms" of HBV DNA were detected in only 5 of the 88 liver samples, 3 of which were from patients with no serologic marker for HBV. In most of the liver samples the DNA patterns were consistent with the presence of HBV or a closely related virus. Of the 105 serum samples tested, HBV DNA sequences were identified in 10 (9.5 per cent), 6 of which had no HBV serologic marker. Moreover, HBsAg-associated determinants were detected in 5 of 17 patients who were positive for HBV DNA and in none of 14 patients who were negative. This study demonstrates the high frequency of HBsAg-negative HBV DNA-positive viral infection of the liver and suggests that multiplication of HBV may occur in the absence of any conventional serologic marker for HBV.

SUMMARYUsing the Southern blot technique, we have analysed the presence and state of hepatitis B virus (HBV) DNA in non-hepatic tissue from two human HBV carriers. HBV DNA sequences were detected in the pancreas, kidney and skin, demonstrating HBV infection of these organs. Moreover, the restriction DNA patterns were consistent with the integration of these viral sequences into high molecular weight DNA. These results demonstrate that HBV infection is not restricted to the liver.Hepatitis B virus (HBV) infects only humans and chimpanzees and is considered to be strictly hepatotropic. In the liver of chronic HBV carriers with or without hepatocellular carcinoma (HCC), integrated HBV DNA sequences have been observed (Br6chot et al., 1981 a;Shafritz et al., 1981; Chert et al., 1982). The restriction enzyme patterns obtained from cellular DNA showed the presence of delineated HBV-specific bands. HBV DNA is therefore a new marker in the study of the relationship between the viral infection and chronic liver diseases. Recent studies have demonstrated the presence of the hepatitis B surface antigen (HBsAg) in pancreatic secretions during pancreatic stimulation (Hoefs et al., 1980) and both the HBsAg and the hepatitis B core antigen (HBcAg) in the cytoplasm of pancreatic acinar cells (Shimoda et al., 1981). It was therefore of interest to investigate the possibility of HBV infection in non-hepatic tissues. For this purpose we have used the Southern blot technique (Southern, 1975;Wahl et al., 1979) with cloned viral DNA (Charnay et al., 1979) as a probe to detect HBV sequences in the DNA of various organs.Tissue samples were obtained at autopsy from two patients. Patient A was an 80 year old woman who died of cirrhosis with HCC. HBsAg, antibodies against the core antigen (anti-HBc) and the e antigen (anti-HBe) were present in her serum. The hepatitis e antigen (HBeAg) was not detected. Histological examination showed a normal pancreas and kidney without metastasis; of the liver only tumorous tissue was available. Patient B was a 67 year old man who died 5 months after the onset of a severe protracted acute hepatitis with massive renal failure due to glomerulonephritis. The acute hepatitis had occurred 2 months after blood transfusion during total pancreatectomy for a pancreatic adenocarcinoma. HBsAg, HBeAg and anti-HBc were present in the serum. A small pancreatic metastasis in the liver was carefully separated from the non-tumorous liver (as checked by histological examination). The kidney histology showed a membranous glomerulonephritis. HBsAg and HBcAg were detected in the tissues by an indirect immunoperoxidase technique using a murine monoclonal anti-HBs and human anti-HBc antibodies (Sternberger, 1979). Cellular DNAs extracted from various organs of the two patients were digested with either EcoRI, which cleaved most HBV genomes once, or HmdIII, which does not cut any of the HBV genomes so far analysed (Wain-Hobson et al., 1982). For patient A (HBsAg-positive, HBeAgnegative in the serum) the EcoRI fragment hybridiz...