Long-term efficacy and safety of sonidegib in patients with advanced basal cell carcinoma: 42-month analysis of the phase II randomized, double-blind BOLT study.

BACKGROUND: Basal cell carcinomas (BCCs) exhibit aberrant activation of the hedgehog pathway. Sonidegib is a hedgehog pathway inhibitor approved for the treatment of locally advanced BCC (laBCC) and metastatic BCC (mBCC) based on primary results of the BOLT study [Basal Cell Carcinoma Outcomes with LDE225 (sonidegib) Treatment]. OBJECTIVES: This is the final 42-month analysis of the BOLT study, evaluating the efficacy and safety of sonidegib. METHODS: Adults with no prior hedgehog pathway inhibitor therapy were randomized in a 1 : 2 ratio to sonidegib 200 mg or 800 mg once daily. Treatment continued for up to 42 months or until disease progression, unacceptable toxicity, death, study termination or withdrawal of consent. The primary efficacy end point was the objective response rate (ORR) by central review, assessed at baseline; weeks 5, 9 and 17; then subsequently every 8 or 12 weeks during years 1 or 2, respectively. Safety end points included adverse event monitoring and reporting. RESULTS: The study enrolled 230 patients, 79 and 151 in the 200-mg and 800-mg groups, respectively, of whom 8% and 3.3% remained on treatment by the 42-month cutoff, respectively. The ORRs by central review were 56% [95% confidence interval (CI) 43-68] for laBCC and 8% (95% CI 0·2-36) for mBCC in the 200-mg group and 46·1% (95% CI 37·2-55·1) for laBCC and 17% (95% CI 5-39) for mBCC in the 800-mg group. No new safety concerns emerged. CONCLUSIONS: Sonidegib demonstrated sustained efficacy and a manageable safety profile. The final BOLT results support sonidegib as a viable treatment option for laBCC and mBCC. What's already known about this topic? Basal cell carcinoma (BCC) is usually treatable with surgery or radiation therapy, but there are limited treatment options for patients with advanced BCC. Sonidegib, a hedgehog pathway inhibitor approved for the treatment of advanced BCC, demonstrated clinically relevant efficacy and manageable safety in prior analyses of the phase II randomized, double-blind BOLT study [Basal Cell Carcinoma Outcomes with LDE225 (sonidegib) Treatment]. What does this study add? This final 42-month analysis of BOLT is the longest follow-up available for a hedgehog pathway inhibitor. Clinically relevant efficacy results were sustained from prior analyses, with objective response rates by central review of the approved 200-mg daily dose of 56% in locally advanced BCC and 8% in metastatic BCC. No new safety concerns were raised. The results confirmed sonidegib as a viable long-term treatment option for patients with advanced BCC.

Long-term efficacy and safety of sonidegib in patients with locally advanced and metastatic basal cell carcinoma: 30-month analysis of the randomized phase 2 BOLT study.

BACKGROUND: Patients with locally advanced basal cell carcinoma (laBCC) or metastatic BCC (mBCC), two difficult-to-treat populations, have had limited treatment options. Sonidegib, a hedgehog pathway inhibitor (HPI), was approved in laBCC based on results from the BOLT trial. OBJECTIVE: To evaluate long-term efficacy and safety of sonidegib in laBCC and mBCC in the BOLT 18- and 30-month analyses. METHODS: BOLT (NCT01327053, ClinicalTrials.gov), a double-blind phase 2 study, enrolled patients from July 2011 until January 2013. Eligible HPI-treatment-naïve patients with laBCC not amenable to curative surgery/radiotherapy or mBCC were randomized 1 : 2 to sonidegib 200 mg (laBCC, n = 66; mBCC, n = 13) or 800 mg (laBCC, n = 128; mBCC, n = 23). Tumour response was assessed per central and investigator review. RESULTS: With 30 months of follow-up, among patients treated with sonidegib 200 mg (approved dose), objective response rates were 56.1% (central) and 71.2% (investigator) in laBCC and 7.7% (central) and 23.1% (investigator) in mBCC. Tumour responses were durable as follows: median duration of response was 26.1 months (central) and 15.7 months (investigator) in laBCC and 24.0 months (central) and 18.1 months (investigator) in mBCC. Five patients with laBCC and three with mBCC in the 200-mg arm died. Median overall survival was not reached in either population; 2-year overall survival rates were 93.2% (laBCC) and 69.3% (mBCC). In laBCC, efficacy was similar regardless of aggressive or non-aggressive histology. Sonidegib 200 mg continued to have a better safety profile than 800 mg, with lower rates of grade 3/4 adverse events (43.0% vs. 64.0%) and adverse events leading to discontinuation (30.4% vs. 40.0%). CONCLUSION: Sonidegib continued to demonstrate long-term efficacy and safety in these populations. These data support the use of sonidegib 200 mg per local treatment guidelines.

Functional and symptom impact of trametinib versus chemotherapy in BRAF V600E advanced or metastatic melanoma: quality-of-life analyses of the METRIC study.

BACKGROUND: In a randomized phase III study, trametinib prolonged progression-free survival and improved overall survival versus chemotherapy in patients with BRAF V600 mutation-positive melanoma. PATIENTS AND METHODS: Patients' quality of life (QOL) was assessed at baseline and follow-up visits using the European Organisation for Research and Treatment of Cancer Core QOL questionnaire. RESULTS: In the primary efficacy population (BRAF V600E+, no brain metastases) from baseline to weeks 6 and 12, patients' global health status scores worsened by 4-5 points with chemotherapy but improved by 2-3 points with trametinib. Rapid and substantive reductions in QOL functionality (e.g. role functioning, 8-11 points at weeks 6 and 12) and symptom exacerbation (e.g. fatigue, 4-8 points; nausea and vomiting, 5 points, both at weeks 6 and 12) were observed in chemotherapy-treated patients. In contrast, trametinib-treated patients reported small improvements or slight worsening from baseline at week 12, depending on the functional dimension and symptom. The mean symptom-scale scores for chemotherapy-treated patients increased from baseline (symptoms worsened) for seven of eight symptoms at week 6 (except insomnia) and six of eight symptoms at week 12 (except dyspnea and insomnia). In contrast, at weeks 6 and 12, the mean symptom-scale scores for trametinib decreased from baseline (symptoms improved) for pain (11-12 points), insomnia (10-12 points), and appetite loss (1-5 points), whereas those for diarrhea worsened (15-16 points). Mixed-model repeated-measures analyses showed significant (P < 0.05) and/or clinically meaningful improvements (small to moderate) from baseline in favor of trametinib for global health; physical, role, and social functioning; fatigue; pain; insomnia; nausea and vomiting; constipation; dyspnea; and appetite at weeks 6 and/or 12. QOL results for the intent-to-treat population were consistent. CONCLUSIONS: This first QOL assessment for a MEK inhibitor in metastatic melanoma demonstrated that trametinib was associated with less functional impairment, smaller declines in health status, and less exacerbation of symptoms versus chemotherapy.

Differential influence of vemurafenib and dabrafenib on patients' lymphocytes despite similar clinical efficacy in melanoma.

BACKGROUND: Since the majority of melanomas eventually become resistant and progress, combining selective BRAF inhibitors (BRAFi) with immunotherapies has been proposed to achieve more durable treatment responses. Here, we explored the impact of selective BRAFi on the hosts' immune system. PATIENTS AND METHODS: Clinical data, whole blood counts (WBC) and serum lactate dehydrogenase (LDH) of 277 vemurafenib- and 65 dabrafenib-treated melanoma patients were evaluated. The frequency and phenotype of lymphocyte subpopulations were determined by flow cytometry while T cell cytokine secretion was measured by multiplex assays. RESULTS: Progression-free survival (PFS) as well as overall survival (OS) were similar in patients treated with either BRAFi. High pretreatment LDH was associated with shorter PFS and OS in both groups. During therapy, peripheral lymphocytes decreased by 24.3% (median, P < 0.0001) in vemurafenib-treated patients but remained unchanged in dabrafenib-treated patients (+1.2%, P = 0.717). Differentiation of peripheral lymphocytes of vemurafenib-treated patients showed a significant decrease in CD4(+) T cells (P < 0.05). Within CD4(+) T cells obtained during treatment, an increase in CCR7(+)CD45RA(+) (naïve) and a decrease in CCR7(+)CD45RA(-) (central memory) populations were found (P < 0.01 for both). Furthermore, secretion of interferon-γ and interleukin-9 by CD4(+) T cells was significantly lower in samples obtained during vemurafenib treatment compared with baseline samples. CONCLUSION: While both compounds have comparable clinical efficacy, vemurafenib but not dabrafenib decreases patients peripheral lymphocyte counts and alters CD4(+) T cell phenotype and function. Thus, selective BRAFi can significantly affect patients' peripheral lymphocyte populations. Fully understanding these effects could be critical for successfully implementing combinatorial therapies of BRAFi with immunomodulatory agents.

Blisters - an unusual effect during radiotherapy.

The skin reaction to radiation is regularly monitored in order to detect enhanced radiosensitivity of the patient, unexpected interactions (e.g. with drugs) or any inadvertent overdosage. It is important to distinguish secondary disease from radiation reaction to provide adequate treatment and to avoid unnecessary discontinuation of radiotherapy. A case of bullous eruption or blisters during radiotherapy of the breast is presented. Differential diagnoses bullous pemphigoid, pemphigus vulgaris, and bullous impetigo are discussed and treatment described.

A randomised, phase II study of intetumumab, an anti-αv-integrin mAb, alone and with dacarbazine in stage IV melanoma.

BACKGROUND: α(v) integrins are involved in angiogenesis and melanoma tumourigenesis. Intetumumab (CNTO 95) is a fully human anti-α(v)-integrin monoclonal antibody. METHODS: In a multicentre, randomised, phase II study, stage IV melanoma patients were randomised 1:1:1:1 to 1000 mg m(-2) dacarbazine+placebo (n=32), 1000 mg m(-2) dacarbazine+10 mg kg(-1) intetumumab (n=32), 10 mg kg(-1) intetumumab (n=33), or 5 mg kg(-1) intetumumab (n=32) q3w. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS), objective response rate (ORR), adverse events, and pharmacokinetics. RESULTS: No statistically significant differences in efficacy were observed between groups. In the dacarbazine+placebo, dacarbazine+intetumumab, 10 mg kg(-1) intetumumab, and 5 mg kg(-1) intetumumab groups, median PFS was 1.8, 2.5, 1.4, and 1.4 months; median OS was 8, 11, 15, and 9.8 months; and ORR of complete+partial response was 10, 3, 6, and 0%. Nonlinear intetumumab pharmacokinetics and potential intetumumab-dacarbazine interactions were observed. Transient, asymptomatic, nonrecurring, grade 1-2, uveitic reactions that resolved spontaneously or with topical steroids were seen in 22-30% of intetumumab-treated patients. Low-grade infusion-reaction symptoms (headache, fatigue, nausea, vomiting, fever, chills) were observed, as expected, in 16-73% of dacarbazine-treated patients. No intetumumab-related myelosuppression, laboratory/electrocardiogram abnormalities, or deaths occurred. CONCLUSION: With its favourable safety profile and a nonsignificant trend towards improved OS, intetumumab merits further investigation in advanced melanoma.

Sorafenib and pegylated interferon-α2b in advanced metastatic melanoma: a multicenter phase II DeCOG trial.

BACKGROUND: The combination of sorafenib, a multikinase inhibitor, and pegylated interferon-α2b (Peg-IFN-α2b) could potentially lead to an improved antitumoral response. Previously, combinations of interferon and sorafenib have been used in renal cell cancer. PATIENTS AND METHODS: Patients with stage IV metastatic melanoma and no previous systemic therapies apart from adjuvant immunotherapy received Peg-IFN-α2b 3 µg/kg once per week, and sorafenib 400-mg b.i.d. for a minimum of 8 weeks. The primary study end point was disease control rate (DCR). RESULTS: Between February 2008 and February 2009, 55 patients were enrolled with a median age of 64 years (20-85). At 8 weeks, 2 patients (3.6%) had a partial response (PR) and 14 patients a stable disease (25.5%), for a DCR of 29.1% in the intention-to-treat (ITT) population. The median progression-free survival in the ITT population was 2.47 months (95% confidence interval 1.22-3.72 months). The toxicity of sorafenib and Peg-IFN-α2b combination was characterized by mainly hematological side-effects, including one treatment-related bleeding complication with a fatal outcome. Other grade 3/4 toxic effects were fatigue and flu-like symptoms. CONCLUSION: The combination of sorafenib and Peg-IFN-α2b showed modest clinical activity and some serious side-effects including fatal bleeding complications.

Algorithm for detection of small-bowel metastasis in malignant melanoma of the skin.

BACKGROUND AND STUDY AIM: The aim of this study was to develop an algorithm to detect small-bowel metastasis (SBM) of melanoma by sequential laboratory parameters and pan-intestinal endoscopy (PIE) including video capsule endoscopy (VCE). PATIENTS AND METHODS: A total of 390 melanoma patients (AJCC stage I/II/III/IV, 140/80/121/49) were screened for signs of intestinal blood loss (fecal occult blood test [FOBT] or overt bleeding) in an open, multicenter, prospective study, and those who were positive underwent PIE. Independent of the presence of intestinal bleeding, all stage IV patients were offered PIE. Follow-up was obtained in 357 patients (91.5 %) for a median of 16 months. We undertook to identify possible associations between SBM and clinical and laboratory data. Survival data were analyzed with regard to clinical and laboratory data and small-bowel findings. RESULTS: Intestinal blood loss was suspected in 49 of 390 patients (12.6 %), 38 of whom (77.6 %) agreed to undergo endoscopy. In 10 patients, SBM was detected by VCE (intention-to-diagnose, 20.4 %; AJCC III, n = 2; AJCC IV, n = 8). The SBM was resected in five patients. Total detection rates of SBM were 14 of 49 patients in stage IV (28.6 %, intention-to-diagnose), 2 of 121 in stage III (1.7 %), and 0 in stage I/II. In FOBT-positive patients, SBM detection rates were 72.7 %, 14.3 %, and 0 % in tumor stages IV, III, and I/II, respectively. Positive FOBT proved to be an independent negative prognostic factor for total survival in stage III and IV melanoma. CONCLUSIONS: SBMs are frequent in advanced melanoma. In stage III patients, screening for intestinal blood loss by PIE may help to identify SBMs. In stage IV, indication for PIE should depend on the individual consequences of detecting SBM, but not on bleeding symptoms alone.

Regression of human metastatic renal cell carcinoma after vaccination with tumor cell-dendritic cell hybrids.

Reports of spontaneous regressions of metastases and the demonstration of tumor-reactive cytotoxic T lymphocytes indicate the importance of the host's immune system in controlling the devastating course of metastatic renal cell carcinoma. Recent research indicates that immunization with hybrids of tumor and antigen presenting cells results in protective immunity and rejection of established tumors in various rodent models. Here, we present a hybrid cell vaccination study of 17 patients. Using electrofusion techniques, we generated hybrids of autologous tumor and allogeneic dendritic cells that presented antigens expressed by the tumor in concert with the co-stimulating capabilities of dendritic cells. After vaccination, and with a mean follow-up time of 13 months, four patients completely rejected all metastatic tumor lesions, one presented a 'mixed response', and two had a tumor mass reduction of greater 50%. We also demonstrate induction of HLA-A2-restricted cytotoxic T cells reactive with the Muc1 tumor-associated antigen and recruitment of CD8+ lymphocytes into tumor challenge sites. Our data indicate that hybrid cell vaccination is a safe and effective therapy for renal cell carcinoma and may provide a broadly applicable strategy for other malignancies with unknown antigens.

The 55-kD tumor necrosis factor receptor on human keratinocytes is regulated by tumor necrosis factor-alpha and by ultraviolet B radiation.

In previous studies we showed that cultured human keratinocytes expressed the 55-kD TNF receptor (TNFR) and that its expression the important for TNF alpha-mediated upregulation of intercellular adhesion molecule-1 (ICAM-1) expression on keratinocytes. Because factors that either reduce or enhance TNFR expression are likely to have a major impact on the biological effects of TNF alpha on keratinocytes, these studies were conducted to determine the factors that regulate its expression on keratinocytes. Using reverse transcriptase polymerase chain reaction, human keratinocytes were shown to lack 75-kD TNFR expression, indicating that TNF responsiveness of human keratinocytes critically depended on regulation of 55-kD TNFR expression. Human keratinocyte 55-kD TNFR surface and mRNA expression was found to be regulated in vitro by recombinant human (rh) TNF alpha. Stimulation of keratinocytes with rhTNF alpha initially decreased, but later increased, 55-kD TNFR surface expression. This biphasic modulation of 55-kD TNFR surface expression was associated with concomitant changes in 55-kD TNFR mRNA expression. Ultraviolet B (UVB) radiation, a well-known inducer of synthesis and secretion of TNF alpha by human keratinocytes, was found to mimic TNF alpha-induced modulation of 55-kD TNFR surface and mRNA expression via a TNF alpha-mediated autocrine regulatory mechanism. Production of soluble 55-kD TNFR by human keratinocytes remained unaffected by TNF alpha stimulation or UVB irradiation. These studies provide clear evidence that membrane expression of the human 55-kD TNFR may be regulated in human keratinocytes by the ligand itself: TNF alpha. Since in previous studies UVB irradiation transiently inhibited TNF alpha-induced human keratinocyte ICAM-1 expression, it is proposed that UVB radiation-induced biphasic modulation of human keratinocyte 55-kD TNFR expression may affect the capacity of these cells to respond to TNF alpha.

Identification of sample-specific sequences in mammalian cDNA and genomic DNA by the novel ligation-mediated subtraction (Limes).

The representational difference analysis (RDA) and other subtraction techniques are used to enrich sample-specific sequences by elimination of ubiquitous sequences existing in both the sample of interest (tester) and the subtraction partner (driver). While applying the RDA to genomic DNA of cutaneous lymphoma cells in order to identify tumor relevant alterations, we predominantly isolated repetitive sequences and artificial repeat-mediated fusion products of otherwise independent PCR fragments (PCR hybrids). Since these products severely interfered with the isolation of tester-specific fragments, we developed a considerably more robust and efficient approach, termed ligation-mediated subtraction (Limes). In first applications of Limes, genomic sequences and/or transcripts of genes involved in the regulation of transcription, such as transforming growth factor beta stimulated clone 22 related gene (TSC-22R), cell death and cytokine production (caspase-1) or antigen presentation (HLA class II sequences), were found to be completely absent in a cutaneous lymphoma line. On the assumption that mutations in tumor-relevant genes can affect their transcription pattern, a protocol was developed and successfully applied that allows the identification of such sequences. Due to these results, Limes may substitute/supplement other subtraction/comparison techniques such as RDA or DNA microarray techniques in a variety of different research fields.

Expression of cyclooxygenase 2 in human malignant melanoma.

Cyclooxygenase (COX)-2 is an inducible enzyme involved in production of prostaglandins in inflammatory processes. There is now increasing evidence that a constitutive expression of COX-2 plays a role in development and progression of malignant epithelial tumors. In the present study we investigated expression and function of COX-2 in malignant melanoma. Expression of COX-2 was determined by immunohistochemistry in 28 cases of primary skin melanoma and 4 benign nevi. We show that COX-2 was expressed in 26 cases (93%) of melanomas, with a moderate to strong expression in 19 cases (68%). Benign nevi as well as normal epithelium were negative in all cases. A constitutive expression of COX-2 mRNA and protein was found in five melanoma cell lines (A375, MeWo, SK-Mel-13, SK-Mel-28, and IGR-37) by using Northern blot as well as immunoblotting. All melanoma cell lines produced prostaglandin (PG) E2 between 468 and 3500 pg/ml as determined by ELISA. Treatment with NS-398 (50 microM), a specific inhibitor of COX-2, suppressed PGE2 production of all melanoma cell lines by 50-96%. The IC50 for inhibition of PGE2 production by NS-398 was determined as 4 microM, indicating that NS-398 acts via inhibition of the COX-2 isoenzyme. We could show that proliferation of melanoma cell lines was not influenced by treatment with NS-398 in concentrations up to 100 microM. However, NS-398 reduced Matrigel invasion of all five malignant melanoma cell lines by 50-68%. Our results indicate that COX-2 is expressed in malignant melanomas and may be involved in regulation of melanoma invasion. It remains to be investigated whether selective inhibitors of COX-2 might be useful for prevention or treatment of malignant melanoma.

Reduced growth factor requirements and accelerated cell-cycle kinetics in adult human melanocytes transformed with SV40 large T antigen.

Melanomas develop with high frequency in transgenic mice in which oncogenic sequences of the SV40 DNA tumor virus have been specifically targeted to melanocytes. To investigate the role of SV40 in melanomagenesis, cultured human melanocytes were transformed with a retroviral shuttle vector encoding the SV40 large T antigen and examined for changes in cell-cycle kinetics and growth-factor dependence. Colonies expressing the viral oncogene were morphologically indistinguishable from their non-T-antigen-transformed counterparts. Also like normal melanocytes, the infected cells remained anchorage dependent and non-tumorigenic in nude mice. However, T-antigen-positive cultures exhibited significantly accelerated population doubling times, increased saturation densities with highly confluent monolayers and a three- to fourfold extended life span. Most interestingly, cell-cycle analysis revealed a measurable shift from quiescent to cycling cells in T-antigen-expressing cultures and an acquired ability to progress more rapidly through G1. Moreover, T-antigen-positive melanocytes proliferated in the absence of PMA and required markedly reduced levels of exogenous bFGF. These studies indicate that the viral oncogen of simian virus 40 provides melanocytes with distinct growth advantages that may render these cells unusually susceptible to additional environmental challenges necessary for full expression of the malignant phenotype.

In situ expression of a B7-like adhesion molecule on keratinocytes from human epidermis.

The B7 adhesion molecule, a member of the immunoglobulin superfamily, has previously been identified primarily on cells of hematopoietic origin. Because B7 has been shown to facilitate interactions with T cells and because cells of the epidermis are proficient at binding and activating T lymphocytes, studies were performed to determine whether B7 was expressed in human epidermis. A subpopulation of brightly staining B7-positive cells was observed in situ in normal human epidermis. Flow-cytometric examination of epidermal cell suspensions that had been cultured for 24 h or longer demonstrated that between 10 and 40% of cells expressed B7 or a closely related antigen. Immunoelectron microscopy, double-staining procedures, and examination of epidermal suspensions depleted of Langerhans cells all confirmed that the B7-positive cells were keratinocytes. These studies identify human epidermal keratinocytes, a non-hematopoietic cell population, as a cell type capable of expressing a B7-like adhesion molecule.

Ultraviolet radiation effects on human keratinocyte ICAM-1 expression: UV-induced inhibition of cytokine-induced ICAM-1 mRNA expression is transient, differentially restored for IFN gamma versus TNF alpha, and followed by ICAM-1 induction via a TNF alpha-like pathway.

Human keratinocytes (KC) during the course of inflammatory dermatoses strongly express the surface molecule ICAM-1, which plays an important role in the generation of the epidermal inflammatory infiltrate by mediating leukocyte-keratinocyte interactions. Accordingly, KC ICAM-1 expression is known to be induced in vivo and in vitro by cytokines either via the TNF alpha/TNF beta or via the IFN gamma-mediated pathway. In contrast, ultraviolet (UV) radiation previously has been found to potently inhibit cytokine-induced KC ICAM-1 surface expression by a sublethal mechanism. In order to further define this novel immunosuppressive effect of UV light, the effects of in vitro UV radiation on ICAM-1 mRNA expression in transformed human KC (KB cells) were examined. Accordingly, UV light (0-100 J/m2) inhibited IFN gamma- as well as TNF alpha-induced ICAM-1 mRNA expression, if KC were cytokine stimulated immediately after irradiation. After a 12-h incubation period, however, IFN gamma responsiveness was found to be restored in irradiated cells, whereas restoration of responsiveness to TNF alpha required at least a 24-h recovery phase. Moreover, UV light alone did not alter ICAM-1 mRNA levels after 4, 12, or 24 h. After 48 h, however, a significant increase in ICAM-1 mRNA and surface expression in UV-irradiated KC could be observed. In addition, this increase could be superinduced by stimulation of irradiated KC with IFN gamma, but not with TNF alpha. UV-induced upregulation of ICAM-1 expression could be mimicked by stimulating unirradiated cells with supernatants derived from UV-irradiated cells. Addition of biologically active anti-TNF alpha antibodies to UV-irradiated cells or to supernatants derived from UV-irradiated KC, however, did not even partially abolish this ICAM-1-inducing activity. UV light thus seems to affect KC ICAM-1 mRNA expression in a biphasic manner: an early period of inhibition of cytokine-induced ICAM-1 expression is transient and followed by restoration of responsiveness to ICAM-1-inducing cytokines. Moreover, UV itself is able to induce ICAM-1 mRNA expression at this later time point via a TNF alpha-like pathway. These studies identify UV irradiation as a potent modulator of cytokine regulated ICAM-1 gene transcription with the capacity to induce both inhibitory as well as enhancing effects.

Analysis of the mechanism of ultraviolet (UV) B radiation-induced prostaglandin E2 synthesis by human epidermoid carcinoma cells.

Stimulation of cultured human keratinocytes with interleukin (IL)-1 alpha is known to elicit prostaglandin (PG) E2 release. Ultraviolet (UV) B radiation induces keratinocyte PGE2 and cytokine production. The present study deals with the autocrine roles of UVB-induced, keratinocyte-derived cytokines IL-1 and tumor-necrosis-factor (TNF) alpha and their corresponding receptor molecules for UVB-induced PGE2 release. In vitro exposure of transformed human keratinocytes (KB cells) induced PGE2 production five- to eightfold. This increase was inhibited by 70%, if irradiated cells were cultured in presence of monoclonal antibody (MoAb) M4, which blocks IL-1 effects by binding to the type 1 IL-1 receptor (IL-1R). In contrast, MoAb M22, which blocks the type 2 IL-1R, had no significant effects. Addition of recombinant human TNF alpha to unirradiated KB cells resulted in five- to eightfold increased PGE2 synthesis, and this increase could be mimicked by stimulation of KB cells with MoAb htr-9, which exerts TNF alpha-like bioactivity by binding to the 55-kD TNF receptor (TNFR). UVB-induced PGE2 synthesis was blocked by 50% in the presence of neutralizing anti-TNF alpha-Ab, and was completely inhibited by addition of both anti-TNF alpha-Ab and MoAb M4. To elucidate a possible regulatory intracellular step in PGE2 synthesis, specific cyclooxygenase activity in KB cells was determined. Following UVB treatment, cyclooxygenase activity increased twofold, but remained unaltered, if irradiated KB cells were cultured in the presence of anti-TNF alpha-Ab plus MoAb M4. These studies indicate that keratinocyte-derived TNF alpha and IL-1 together mediate UVB-induced PGE2 release via specific cell surface receptors, and that one intracellular mechanism is an increased prostanoid-synthesizing capacity of irradiated cells.

55-kd tumor necrosis factor receptor is expressed by human keratinocytes and plays a pivotal role in regulation of human keratinocyte ICAM-1 expression.

Tumor necrosis factor alpha (TNF alpha) is a potent modulator of human keratinocyte intercellular adhesion molecule-1 (ICAM-1) expression. TNF alpha is known to exert its biologic effects by binding to specific cell-surface receptors. Two distinct TNF binding molecules, the 55-kd and the 75-kd TNF receptor (TNFR) recently have been found to be expressed by human cells. These two receptor types are independently regulated and differ markedly in their intracellular regions, indicating functional dichotomy. In order to gain further insight into the mechanisms underlying ICAM-1 regulation in human keratinocytes, in the present study, the receptor molecules mediating TNF alpha induced ICAM-1 upregulation in human keratinocytes was defined. Human keratinocyte TNFR expression was assessed using monoclonal antibodies that specifically recognize the 55-kd or the 75-kd TNFR. Using FACS analysis, normal (HNK) as well as transformed (KB) human keratinocytes were found to react with anti-55-kd TNFR, but not anti-75-kd TNFR antibodies. These immunofluorescence data were confirmed by Northern blot analysis revealing clearly detectable amounts of mRNA specific for the 55-kd TNFR in KB cells. Incubation of human keratinocytes with anti-55-kd TNFR antibodies at 37 degrees C for 24 h increased ICAM-1 expression in a TNF alpha-like fashion. Moreover, the well known synergistic effect of IFN gamma plus TNF alpha on keratinocyte ICAM-1 induction could be mimicked by stimulation of cells with IFN gamma plus anti-55-kd TNFR antibodies. Synergistic ICAM-1 induction was not associated with increased expression of the 55-kd TNFR in IFN gamma-stimulated human keratinocytes. These studies indicate that human keratinocytes express the 55-kd TNF receptor and that this surface molecule may play an important role in regulation of human keratinocyte ICAM-1 expression.