The activity of single-agent carboplatin in advanced seminoma

Between 1982 and 1990, 70 patients with advanced metastatic seminoma were treated with 4-6 courses of single-agent carboplatin (SAC) administered at 400 mg/m2 every 3-4 weeks. Treatment was of low toxicity and no patients suffered neurotoxicity, ototoxicity or significant renal damage. There was only one episode of neutropenic sepsis and no thrombocytopenic bleeding. The median follow-up of surviving patients was 3 years. 16 patients have relapsed and 4 of these 16 have died, thus the actuarial 3-year relapse-free survival was 77% (95% CI 65-86%), cause-specific survival was 94% (95% CI 82-99%) and overall survival was 91% (95% CI 80-96%). The risk of relapse was reduced by post-chemotherapy irradiation (PCRT) to involved nodes, occurring in 1/20 patients treated with PCRT compared with 11/31 who could have been treated but were not (P = 0.04). Of the 16 patients who relapsed, 12(75%) have been salvaged with combination chemotherapy and remain free from further relapse with a median follow-up of 18 months. Though this level of survival is equivalent to that obtained with initial cisplatin-based combination chemotherapy, the recurrence rate indicates that SAC remains an investigative treatment, except for unfit patients.

UV activation of human immunodeficiency virus gene expression in transgenic mice

Human immunodeficiency virus (HIV) infection is associated with a clinical latency of as long as 10 years before the development of disease. One explanation for this delay is the requirement of cofactors such as other DNA or RNA viruses, cytokines critical for immune modulation, or environmental UV light. At least in tissue culture studies, these agents are capable of inducing HIV gene expression in cell lines which either harbor the entire viral genome or contain a reporter gene under the control of the viral long terminal repeat regulatory region. The role of these cofactors in terminating clinical latency and inducing disease has been difficult to ascertain because of the lack of an appropriate animal model. We now report that UV light can markedly induce HIV gene expression in transgenic mice carrying both the cis-acting (long terminal repeat) and trans-acting (the tat gene) elements which are essential for viral transactivation and replication in infected cells. Our finding may explain the clinical observations that cutaneous lesions in HIV-infected individuals are often seen in the sunlight exposed areas of the skin, including the face and neck.

Liver cancer in transgenic mice carrying the human immunodeficiency virus tat gene

Patients with the acquired immunodeficiency syndrome are at risk to develop a variety of different cancers. Based on epidemiological data, Kaposi's sarcoma and non-Hodgkin's lymphoma have been clearly associated with infection by the human immunodeficiency virus (HIV). Additional cancers such as basal cell and squamous cell carcinomas, melanoma, and hepatocellular carcinoma have also been reported to be associated with a diagnosis of acquired immunodeficiency syndrome. A direct causal role of HIV has yet to be established for any of these cancers. We now report that transgenic mice carrying the HIV tat gene develop a high incidence of hepatocellular carcinoma after a long latency and that these changes in the liver are likely to be initiated by extrahepatic growth signals from the tat expressing cells in these mice. We predict that as acquired immunodeficiency syndrome patients begin to respond to therapy and show prolonged survival, such "secondary" malignancies induced by HIV will become increasingly prevalent.

Transgenic mouse model for central nervous system demyelination

A common feature of demyelinating diseases such as multiple sclerosis in humans and experimental autoimmune encephalomyelitis in rodents is the marked elevation in the expression of the major histocompatibility complex (MHC) antigens in the involved sites. By specific targeting of a syngeneic MHC class I gene to oligodendrocytes, we have generated transgenic mice which not only exhibit severe involuntary tremors and develop tonic seizures but also show extensive demyelination in both the brain and the spinal cord. The fact that demyelination in these mice occurs in the absence of immune infiltration dismisses an autoimmune involvement but suggests that the MHC class I antigens play a direct role in inducing disease. Our findings lend support to the possibility that demyelinating diseases are induced by infectious agents such as viruses which can either directly activate MHC gene expression in oligodendroglia or indirectly activate expression through the release by reactive T cells of gamma interferon in the brain.

Overexpression of transforming growth factor-beta in transgenic mice carrying the human T-cell lymphotropic virus type I tax gene

Human T-cell lymphotropic virus type I (HTLV-I) has been associated with an adult form of T-cell leukemia as well as tropical spastic paraparesis, a neurodegenerative disease. Adult T-cell leukemia patients express high levels of the type 1 isoform of transforming growth factor-beta (TGF-beta 1), which is mediated by the effects of the HTLV-I Tax transactivator protein on the TGF-beta 1 promoter. To understand further the regulation of TGF-beta 1 expression by Tax, we examined its expression in transgenic mice carrying the HTLV-I tax gene. We show that tumors from these mice and other tissues, such as submaxillary glands and skeletal muscle, which express high levels of tax mRNA selectively express high levels of TGF-beta 1 mRNA and protein. Moreover, TGF-beta 1 significantly stimulated the incorporation of tritiated thymidine into one of three cell lines derived from neurofibromas of tax-transgenic mice, which suggests that the excessive production of TGF-beta 1 may play a role in tumorigenesis and that these mice may serve as a useful model for studying the biological effects of TGF-beta in vivo.

Effects of H-2Kb gene on expression of melanoma-associated antigen and lectin-binding sites on BL6 melanoma cells

An H-2Kb negative BL6 melanoma clone (BL6-8) was transfected with plasmids containing either the class I H-2Kb or class II H-2IAk gene in combination with the neor gene. The effects of the transfected genes on the expression of the melanoma-associated antigen (MAA) recognized by the monoclonal antibodies MM2-9B6 and MM2-3C6 and the cell surface carbohydrates recognized by 15 different lectins were studied. The original H-2Kb- clone or clones transfected with neor or class II H-2IAk genes expressed high levels of MAA and very low levels of soybean agglutinin (SBA), Griffonia simplicifolia I-B4 (GSIB4), and peanut agglutinin (PNA) lectin-binding sites. In contrast, clones that expressed high levels of the transfected H-2Kb gene completely lost the expression of MAA. In addition, these clones were characterized by the appearance of high levels of expression of the sugars specifically reacting with SBA, GSIB4, and PNA lectins. When the original BL6-8 clone was transfected with the H-2Kd gene, 25 clones subsequently isolated had relatively low expression of the transfected H-2Kd gene but high expression of the endogenous H-2Kb gene accompanied by an alteration in expression of the MAA and lectin binding identical with patterns common for H-2Kb+ melanoma cells. These changes were not due to the transfection, plasmid construction, or place of insertion, since similar phenotypic characteristics were found in H-2Kb+ but not H-2Kb- clones isolated from the N-methyl-N'-nitro-N-nitrosoguanidine-treated BL6T2 or parental BL6 melanoma lines. In total, 73 BL6 melanoma clones were investigated and all of the 41 H-2Kb+ clones displayed loss of MAA and appearance of SBA, GSIB4, and PNA-binding sugars. None of the 32 H-2Kb- clones showed these changes. This study indicates that the class I H-2Kb gene product might alter several phenotypic properties of BL6 melanoma cells. The mechanisms of these changes remain unknown. We consider that these effects of the class I H-2Kb gene are indirect, involving interactions with the B-tropic ecotropic retrovirus specific for melanomas of C57BL/6 mice origin.

Financial strain and psychological well-being among the American and Japanese elderly

Research in the United States indicates that stressful life events may create psychological distress among older adults by eroding their sense of personal control and by diminishing their feelings of self-worth. The purpose of this study was twofold: (a) to replicate these findings with data provided by a recent nationwide survey of elderly people in the United States (N = 1,523) and (b) to compare these findings with results obtained from a nationwide survey of older adults in Japan (N = 1,517). The findings from both surveys are quite similar. The data indicate that financial strain tends to erode feelings of control and self-worth in both cultures, and the weakening of these personal resources in turn tends to increase depressive symptoms.

Combination chemotherapy with bleomycin, etoposide and cisplatin (BEP) for metastatic testicular teratoma: long-term follow-up

127 men with previously untreated non-seminomatous germ cell tumours (NSGCT) of the testis were given BEP chemotherapy (bleomycin, etoposide and cisplatin) between 1979-1986. Long-term follow-up (median 65 months) has shown an overall 5 year survival of 87.2% (95% confidence limits 81.1%-93.3%). Outcome was related to both tumour volume and serum marker levels of alpha-fetoprotein (alpha FP) and beta human chorionic gonadotropin (HCG), with 5 year actuarial survivals of 97.8%, 72.2% and 26.7% respectively for small, large and very large volume disease defined by Medical Research Council criteria, and 91.2% and 60.8%, respectively, for men with low (alpha FP less than or equal to 500 kU/l and HCG less than or equal to 1000 iU/l) or high serum marker levels. 79 men (62%) had a complete radiological and serum marker response to chemotherapy alone; residual masses postchemotheraphy were resected in 39 patients (31%), showing undifferentiated tumour in only 6 (15%). 23 of the 127 patients (18%) failed to respond or developed recurrent disease after BEP; only 5 were successfully salvaged. Myelotoxicity of treatment was mild with grade 4 toxicity in 2% of chemotherapy courses and 3 episodes of neutropenic sepsis. Mean glomerular filtration rates fell by 15.6% between courses 1 and 4 of BEP. Bleomycin pneumonitis developed in 13% of cases with 1 fatality. So far 21 men have had children following chemotherapy, but semen analysis 12 months or more (median 36 months) after treatment showed azoospermia in 11 out of 54 (20%) men tested. BEP chemotherapy can be regarded as standard treatment for patients with metastatic NSGCT in low-risk categories, but more intensive therapy is required for advanced presentations. Strategies to develop "risk related" treatment are under investigation.

HBx gene of hepatitis B virus induces liver cancer in transgenic mice

The exact role of hepatitis B virus in the development of liver cancer is not known. The recent identification of a viral regulatory gene HBx suggests a possible direct involvement of the virus whereby the HBx protein, acting as a transcriptional transactivator of viral genes, may alter host gene expression and lead to the development of hepatocellular carcinoma. We have tested this possibility of placing the entire HBx gene under its own regulatory elements directly into the germline of mice. Transgenic animals harbouring this viral gene succumbed to progressive histopathological changes specifically in the liver, beginning with multifocal areas of altered hepatocytes, followed by the appearance of benign adenomas, and proceeding to the development of malignant carcinomas. Male mice developed disease and died much earlier than females. This transgenic animal model appears ideal for defining the molecular events that follow the expression of the viral HBx gene and are responsible for the development of liver cancer.

Effectiveness of carboplatin, etoposide, and bleomycin combination chemotherapy in good-prognosis metastatic testicular nonseminomatous germ cell tumors

The combination of carboplatin, etoposide, and bleomycin (CEB) was evaluated as initial chemotherapy in 76 patients with good-prognosis metastatic nonseminomatous germ cell tumors (NSGCT) between 1984 and 1988. The classification of eligible patients included Royal Marsden Hospital (RMH) stages IM, IIA, IIB, IIC, IIIA, IIIB, IV0ABCL1, and IV0ABL2. Four courses of combination chemotherapy were administered in a 21-day cycle, and surgical excision of residual mass was performed in 27 cases (23 laparotomies and four thoracotomies). At the time of analysis, median follow-up was 24 months from start of chemotherapy (range, 6 to 54 months). The 2-year cause-specific survival probability was 98.5%, the single cause-related mortality being caused by bleomycin pneumonitis. Five patients failed CEB chemotherapy, but all have been successfully salvaged with a combination of surgery and intensive chemotherapy, follow-up from completion of all treatment being 35 to 44 months. The toxicity of CEB included bone marrow suppression and alopecia in all patients but no significant neurotoxicity or ototoxicity, and minimal renal toxicity. Only four (5%) patients had a decrease in the glomerular filtration rate greater than 15%. In 51% of patients, the hemoglobin fell below 10 g/dL. The WBC count nadir was less than 1,500/microL in 11% of treatment cycles and in 16% the platelet nadir fell below 50,000/microL. Decreases in the WBC and platelet counts were of very brief duration. Only one of 310 CEB cycles was complicated by neutropenic sepsis, and there were no episodes of thrombocytopenic purpura or bleeding. We conclude that the CEB combination represents an effective alternative to cisplatin-based chemotherapy in good-prognosis NSGCT and that the replacement of cisplatin by carboplatin leads to reduced toxicity.

Financial strain and psychological well-being among the American and Japanese elderly

Research in the United States indicates that stressful life events may create psychological distress among older adults by eroding their sense of personal control and by diminishing their feelings of self-worth. The purpose of this study was twofold: (a) to replicate these findings with data provided by a recent nationwide survey of elderly people in the United States (N = 1,523) and (b) to compare these findings with results obtained from a nationwide survey of older adults in Japan (N = 1,517). The findings from both surveys are quite similar. The data indicate that financial strain tends to erode feelings of control and self-worth in both cultures, and the weakening of these personal resources in turn tends to increase depressive symptoms.

The molecular basis for the generation of the human soluble interleukin 2 receptor

Using an enzyme-linked immunosorbent assay (ELISA) employing two monoclonal antibodies recognizing distinct epitopes on the interleukin 2 receptor (IL2R) alpha chain (Tac molecule), we previously demonstrated that activated lymphocytes release a soluble interleukin 2 receptor molecule (sIL2R) in vitro and in vivo. The sIL2R is biochemically and structurally related to Tac, but its precise origin and functional role remain to be defined. We report here that a single IL2R cDNA is sufficient to direct the synthesis of both cell-associated and soluble released IL2R molecules. Northern analysis of IL2R cDNA transfected L-cell lines revealed the presence of mRNA species unaccounted for by known transcription termination or internal splice sites. Nevertheless, S1 nuclease digestion studies failed to detect alternately spliced mRNA transcripts that specifically lack transmembrane or cytoplasmic domains and which may encode a secreted IL2R molecule. Therefore sIL2R does not appear to be the product of a unique post-transcriptional splicing event. In the absence of any post-translational modifications, sIL2R is most likely generated by enzymatic cleavage and release of cell surface Tac. This proteolytic release of Tac may be but one example of a common cellular mechanism for regulating the membrane expression of cell surface molecules.

Increased sensitivity to MHC-nonrestricted lysis of BL6 melanoma cells by transfection with class I H-2Kb gene

An H-2Kb- negative clone of BL6 melanoma (BL6-8) was transfected with neor, H-2Kb, or H-2IAk genes. In an 18-h cytotoxicity assay clones with high levels of H-2Kb Ag expression were found more sensitive to lysis by spleen cells of syngenic and allogeneic mice than H-2Kb low clones. NK cells were involved in the lysis of H-2Kb+ BL6 melanoma clones, with spleen cell cytotoxicity of mice increased after poly I:C stimulation or decreased after pretreatment with anti-asialo GM1 serum or NK1.1 mAb. Anti-TNF Ab were also able to reduce the cytotoxicity of normal spleen cells and completely abolished the cytotoxicity of the NK-depleted spleen cells suggesting involvement of NC cells in lysis of H-2Kb+ BL6 melanoma clones. Increase in sensitivity of H-2Kb+ BL6 cells to natural cell-mediated cytotoxicity was associated with the appearance of NK recognizable determinants as assessed by the cold target inhibition assay. All BL6 clones, irrespective of sensitivity to natural cell-mediated cytotoxicity, showed high sensitivity to lysis by LGL-derived granules. In contrast, all H-2Kb low BL6 clones were resistant and all H-2Kb highly positive clones were sensitive to lysis by TNF-alpha. When an H-2Kb highly positive clone was selected in vitro for resistance to TNF, it concomitantly showed increased resistance to cytotoxicity by spleen cells, confirming the importance of TNF in spleen cell cytotoxicity against H-2Kb+ melanoma cells. Taken together, the data indicate that class I H-2Kb but not class II H-2IAk gene product could increase the sensitivity of BL6 cells to lysis by NK and natural cytotoxic cells as well as TNF. We hypothesize that these effects could be due to pleiotropic effects of H-2Kb gene products on various biologic properties of BL6 melanoma cells some of which may be more directly involved in regulation of tumor cell sensitivity to lysis by NK and/or natural cytotoxic cells.

Increased sensitivity to MHC-nonrestricted lysis of BL6 melanoma cells by transfection with class I H-2Kb gene

An H-2Kb- negative clone of BL6 melanoma (BL6-8) was transfected with neor, H-2Kb, or H-2IAk genes. In an 18-h cytotoxicity assay clones with high levels of H-2Kb Ag expression were found more sensitive to lysis by spleen cells of syngenic and allogeneic mice than H-2Kb low clones. NK cells were involved in the lysis of H-2Kb+ BL6 melanoma clones, with spleen cell cytotoxicity of mice increased after poly I:C stimulation or decreased after pretreatment with anti-asialo GM1 serum or NK1.1 mAb. Anti-TNF Ab were also able to reduce the cytotoxicity of normal spleen cells and completely abolished the cytotoxicity of the NK-depleted spleen cells suggesting involvement of NC cells in lysis of H-2Kb+ BL6 melanoma clones. Increase in sensitivity of H-2Kb+ BL6 cells to natural cell-mediated cytotoxicity was associated with the appearance of NK recognizable determinants as assessed by the cold target inhibition assay. All BL6 clones, irrespective of sensitivity to natural cell-mediated cytotoxicity, showed high sensitivity to lysis by LGL-derived granules. In contrast, all H-2Kb low BL6 clones were resistant and all H-2Kb highly positive clones were sensitive to lysis by TNF-alpha. When an H-2Kb highly positive clone was selected in vitro for resistance to TNF, it concomitantly showed increased resistance to cytotoxicity by spleen cells, confirming the importance of TNF in spleen cell cytotoxicity against H-2Kb+ melanoma cells. Taken together, the data indicate that class I H-2Kb but not class II H-2IAk gene product could increase the sensitivity of BL6 cells to lysis by NK and natural cytotoxic cells as well as TNF. We hypothesize that these effects could be due to pleiotropic effects of H-2Kb gene products on various biologic properties of BL6 melanoma cells some of which may be more directly involved in regulation of tumor cell sensitivity to lysis by NK and/or natural cytotoxic cells.

Activation of retrovirus in transgenic mice: association with development of olfactory neuroblastoma

A line of transgenic mice that express the human adenovirus type 12 E1A and E1B genes under the regulatory control of the mouse mammary tumor virus long terminal repeat was studied. Mice from this line develop olfactory neuroblastomas at approximately 6 months of age. Large numbers of type C retrovirus (ecotropic murine leukemia virus) particles were found in the tumor rosettes. No similar examples of virus activation were identified in tumors from other transgenic experiments. Examination of spontaneous olfactory neuroblastomas from three domestic cats also demonstrated retrovirus in tumor rosettes.

Orchidectomy alone for stage I seminoma of the testis

Between 1983 and 1988, 113 patients with Stage I seminoma were managed after orchidectomy by surveillance rather than adjuvant radiotherapy. The actuarial risk of relapse at 3 years was 15.8% (95% confidence interval, 7.8% to 23.8%). All 13 patients who experienced a relapse are currently in remission (4 to 45 months after salvage therapy), although 5 suffered second relapses requiring further treatment. Close surveillance is a safe alternative to adjuvant radiotherapy in Stage I seminoma. However, the policy requires prolonged observation of patients with intensive use of resources. Therefore, adjuvant radiotherapy should be considered the treatment of choice.

Glucocorticoid-enhanced neoplastic transformation of human keratinocytes by human papillomavirus type 16 and an activated ras oncogene

Human papillomaviruses (HPV) are known etiological agents of benign proliferation of the skin and mucosa (papillomas and warts). They have also been implicated in the development of cervical dysplasia and anogenital carcinoma. The close association of HPV type 16 DNA with the majority of cervical carcinomas suggests the involvement of the virus in this type of cancer. We have developed an in vitro multistep model for human epithelial cell carcinogenesis. Primary human epidermal keratinocytes acquired an indefinite lifespan in response to transfection with HPV 16 DNA but did not undergo malignant conversion. Addition of Kirsten murine sarcoma virus (Ki-MSV), which contains an activated K-ras oncogene, to these cells induced morphological alterations associated with the acquisition of neoplastic properties. The frequency of transformation by Ki-MSV was markedly enhanced by the inclusion of glucocorticoid. At optimal conditions, a 125-fold stimulation was observed. These findings demonstrate the malignant conversion of human primary epithelial cells in culture by the cooperation of HPV type 16 and an activated ras oncogene and support a multistep process for neoplastic conversion. The availability of a human epithelial cell transformation model should facilitate studies of the interaction between HPV and human epithelial cells.

Suppression of MHC class I RNA in highly oncogenic cells occurs at the level of transcription initiation

The oncogenic potential of some transformed cell lines has been shown in animal tumor models to be the direct result of MHC class I mRNA suppression. Rodent cells established with the highly oncogenic human adenovirus type 12 exhibit greatly reduced levels of class I Ag compared with cells derived with the nononcogenic adenovirus type 5. By using seven independently derived adenovirus-transformed cell lines, we have investigated the mechanism responsible for down-regulation of class I RNA expression. In all adenovirus 12-transformed cells examined, class I RNA suppression was the result of a block in transcription initiation. Highly oncogenic cell lines derived from a spontaneous melanoma and a chemically induced sarcoma also showed greatly reduced transcription of class I genes. We conclude that suppression of MHC class I RNA in a variety of highly oncogenic cells results largely from a substantial decrease in transcription initiation.

Suppression of MHC class I RNA in highly oncogenic cells occurs at the level of transcription initiation

The oncogenic potential of some transformed cell lines has been shown in animal tumor models to be the direct result of MHC class I mRNA suppression. Rodent cells established with the highly oncogenic human adenovirus type 12 exhibit greatly reduced levels of class I Ag compared with cells derived with the nononcogenic adenovirus type 5. By using seven independently derived adenovirus-transformed cell lines, we have investigated the mechanism responsible for down-regulation of class I RNA expression. In all adenovirus 12-transformed cells examined, class I RNA suppression was the result of a block in transcription initiation. Highly oncogenic cell lines derived from a spontaneous melanoma and a chemically induced sarcoma also showed greatly reduced transcription of class I genes. We conclude that suppression of MHC class I RNA in a variety of highly oncogenic cells results largely from a substantial decrease in transcription initiation.

Prevention of allogeneic bone marrow graft rejection by H-2 transgene in donor mice

Rejection of bone marrow grafts in irradiated mice is mediated by natural killer (NK) cells and is controlled by genes linked to the major histocompatibility complex (MHC). It has, however, not been possible to identify the genes or their products. An MHC class I (Dd) transgene introduced in C57BL donors prevented the rejection of their bone marrow by NK cells in irradiated allogeneic and F1 hybrid mice expressing the Dd gene. Conversely, H-2Dd transgenic C57BL recipients acquired the ability to reject bone marrow from C57BL donors but not from H-2Dd transgenic C57BL donors. These results provide formal evidence that NK cells are part of a system capable of rejecting cells because they lack normal genes of the host type, in contrast to T cells, which recognize cells that contain abnormal or novel sequences of non-host type.

trans activation of granulocyte-macrophage colony-stimulating factor and the interleukin-2 receptor in transgenic mice carrying the human T-lymphotropic virus type 1 tax gene

Three lines of transgenic mice carrying the human T-cell lymphotropic virus type 1 tax gene have previously been reported to develop neurofibromas composed of perineural fibroblasts (S. H. Hinrichs, M. Nerenberg, R. K. Reynolds, G. Khoury, and G. Jay, Science 237:1340-1343, 1987; M. Nerenberg, S. H. Hinrichs, R. K. Reynolds, G. Khoury, and G. Jay, Science 237:1324-1329, 1987). Tumors from these mice and tumor cell lines derived from them expressed high levels of tax RNA and protein. They also expressed high levels of the granulocyte-macrophage colony-stimulating factor (GM-CSF) gene as measured by proliferative responses of FD-CP1 target cells using conditioned media from tumor cells and by Northern (RNA) blot analysis of RNA from tumors and tumor cell lines. Although other tissues, such as salivary glands and muscles, in the transgenic mice also expressed high levels of tax, they did not express the gene for GM-CSF. This indicates that tissue-specific cellular factors, in addition to tax, are required for GM-CSF gene expression. Systemic effects of excessive GM-CSF production were demonstrated by infiltration of polymorphonuclear leukocytes into tumor tissues which are not necrotic, by peripheral granulocytosis, and by splenomegaly resulting from myeloid hyperplasia. The interleukin-2 (IL-2) receptor was also found to be expressed by the tumors and tumor cell lines as measured by IL-2-binding and cross-linking studies. This is the first demonstration that the IL-2 receptor can be activated by tax in a nonlymphoid cell type. These in vivo findings are consistent with other reports which have demonstrated in vitro cis-regulatory elements within the 5'-flanking regions of the genes for GM-CSF and the IL-2 receptor which are responsive to trans activation by the tax gene.

Neoplastic transformation of human keratinocytes by polybrene-induced DNA-mediated transfer of an activated oncogene

Polybrene, in conjunction with dimethyl sulfoxide (DMSO) shock has been shown to increase the frequency of DNA-mediated gene transfer to mammalian cells as compared with the frequency obtained with calcium phosphate transfection. We have successfully adapted this procedure for use with human epidermal keratinocytes. Non-tumorigenic human epidermal epithelial cells immortalized by SV40 tumor antigen were neoplastically transfected, using Polybrene at a concentration of 10 micrograms ml-1, followed by a 4 min shock, with 30% DMSO, with a plasmid carrying the activated H-ras gene from the EJ bladder carcinoma cell line. The transfected cells showed morphological alterations and induced carcinomas when transplanted into nude mice. They contained integrated copies of the transfected H-ras gene and expressed high levels of the p21 protein. Polybrene-induced DNA transfection, therefore, offers the opportunity to transfer genes effectively into human epidermal keratinocytes and should accelerate the study of the interaction between oncogenes and human epithelial cells. This study appears to represent the first neoplastic conversion of nontumorigenic, immortalized human epidermal keratinocytes by an activated human oncogene.

Exocrinopathy resembling Sjögren's syndrome in HTLV-1 tax transgenic mice

Human T-cell leukaemia virus 1 (HTLV-1) is a retrovirus aetiologically associated with adult T-cell leukaemia (ATL), tropical spastic paraparesis (TSP) and possibly multiple sclerosis (MS) in humans. Three founder lines of transgenic mice containing the HTLV-1 tax gene under the control of the viral long terminal repeat (LTR) have previously been shown to develop neurofibromas. Further analysis of these animals has now revealed that they also develop an exocrinopathy involving the salivary and lachrymal glands. This pathology resembles Sjögren's syndrome, a disease of presumed autoimmune aetiology, features of which are sometimes reported in HTLV-1 associated conditions. Mice with an HTLV-1 tax transgene might be a useful model for studying the development of Sjögren-syndrome-like pathology.