P16 positivity and regression grade predict survival after neoadjuvant radiotherapy of OSCC.

OBJECTIVES: Survival after preoperative radiotherapy in locally advanced head and neck squamous cell cancer is associated with pathological response. The prognostic importance of p16 expression in these patients has not been established yet. MATERIALS AND METHODS: Ninety-seven patients with oral squamous cell carcinoma, treated preoperatively with radiotherapy in combination with chemotherapy or cetuximab, were included in this retrospective analysis. Survival rates were estimated by the Kaplan-Meyer method. Pathological response was evaluated by histological analysis and p16 expression by immunohistochemistry. RESULTS: Overall survival after 2 years was 66% for the entire group, 92% in the p16-positive and 62% in the p16-negative group, respectively. 12.4% of the tumours were p16-positive. P16 expression (HR 6.98, p = .05) and regression grade (HR 2.94, p = .001) had a statistically significant impact on prognosis. 83.3% of p16-expressing tumours were pathological responders. All p16-positive patients with pathological response were alive within the observation period. CONCLUSION: P16 expression is associated with prognosis in preoperatively irradiated OSCC patients. The association between p16 positivity, regression grade and improved survival provides a rationale for de-intensification strategies in patients with head and neck cancer who respond well to neoadjuvant therapy, a concept that is being tested in prospective clinical trials.

HCRP1 expression status is a significant prognostic marker in oral and oropharyngeal cancer.

OBJECTIVE: The hepatocellular carcinoma-related protein 1 (HCRP1) is a key factor in the degradation of the epidermal growth factor receptor. In this study, we assessed the prognostic significance of HCRP1 expression in patients with oral and oropharyngeal squamous cell carcinoma (OOSCC). METHODS: HCRP1 expression was determined by immunohistochemistry on tissue biopsy sections of 111 patients with locally advanced OOSCC undergoing neoadjuvant chemoradiotherapy followed by surgery. The Kaplan-Meier method and Cox regression models were used for survival analyses. RESULTS: Low HCRP1 expression was associated with poor recurrence-free survival (P = 0.046) and overall survival (P = 0.03). Multivariate analysis revealed that low HCRP1 expression remained an independent risk factor for relapse (HR 2.98, 95% CI 1.19-7.49, P = 0.02) and death (HR 3.04, 95% CI 1.19-7.79, P = 0.02). CONCLUSION: Low HCRP1 expression was found to be of adverse prognostic significance in patients with OOSCC who received preoperative chemoradiotherapy.

[Biological effect and tumor risk of diagnostic x-rays. The "war of the theories"]. / Biologische Wirkung und Tumorrisiko diagnostischer Röntgenstrahlen. Der "Krieg der Modelle".

Since the introduction of ionizing radiation as a treatment and diagnostic tool in humans, scientists have been trying to estimate its side effects and potential health risks. There is now ample evidence for the principal existence of a direct relationship between higher doses and the risks of side effects. Most of the uncertainties lie in the field of low-dose effects especially with respect to the risk of cancer induction. Low-dose effects are usually of relevance in diagnostic medicine while high-dose radiation effects are typically observed after radiotherapeutic treatment for cancer or after nuclear accidents. The current state of the "war of theories" may be summarized as follows: one group of scientists and health regulatory officials favors the hypothesis that there is no threshold dose, i.e. the linear-no-threshold hypothesis (LNT) of radiation which can be regarded as safe. On the contrary, the critics of this hypothesis suggest that the risks of doses below 50 mSv are not measurable or even of clinical relevance and are not adequately described by a linear dose-response relationship. The aim of this article is to summarize the major unresolved issues in this field. Arguments are presented why the validity of the LNT model in the low-dose range should be regarded as at least inconsistent and is thus questionable.

Re-irradiation combined with capecitabine in locally recurrent squamous cell carcinoma of the head and neck. A prospective phase II trial.

BACKGROUND: We performed a prospective phase II trial to investigate the safety and efficacy of radiotherapy combined with capecitabine in patients suffering from a recurrence of a squamous cell carcinoma of the head and neck (SCCHN) within a previously irradiated field. PATIENTS AND METHODS: A total of 31 evaluable patients with recurrent SCCHN received re-irradiation with a total dose of 50 Gy (25 fractions over 5 weeks) up to a maximum of 60 Gy combined with 900 mg/m(2)/day capecitabine given on the days of radiotherapy. RESULTS: The median time to relapse after the first course of radiotherapy was 15 months. The overall response rate in our study was 68% including 6 patients with a complete response. The median overall survival was 8.4 months. Grade 3 or 4 mucositis occurred in 4 patients and 1 patient, respectively. No grade 4 hematological toxicities were observed; 1 patient had grade 3 anemia. The cumulative median lifetime dose was 116 Gy. CONCLUSION: Capecitabine combined with re-irradiation is a well-tolerated treatment in patients with recurrent SCCHN. In light of its good tolerability, it appears to be a potential option for patients with a reduced performance status and may also serve as a basis for novel treatment concepts, such as in combination with targeted therapies.

Characterization of NVX-207, a novel betulinic acid-derived anti-cancer compound.

BACKGROUND: Development of betulinic acid derivatives for clinical use has been hampered by adverse pharmacological and physico-chemical characteristics of this class of compounds. We here present a novel semi-synthetic betulinic acid-derived drug candidate well suited for further clinical development. MATERIALS AND METHODS: In vitro activity and mode of action of NVX-207 were determined using normal as well as cancer cell lines. Gene expression profiling was performed with Affymetrix U133 microarrays. NVX-207 binding partners were identified using a heterobifunctional chemical crosslinker system. Potential binding proteins were identified by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis. Clinical studies were conducted in canine cancer patients suffering from spontaneously arising pre-treated tumours. RESULTS: NVX-207 showed anti-tumour activity (mean IC(50) = 3.5 microM) against various human and canine cell lines. NVX-207-induced apoptosis was associated with activation of the intrinsic apoptotic pathway via cleavage of caspases -9, -3, -7 and of poly (ADP-ribose) polymerase (PARP). Global gene expression profiling demonstrated regulation of genes associated with lipid metabolism, most notably an upregulation of genes coding for insulin-induced gene 1 (Insig-1), low-density lipoprotein receptor (LDL-R) and of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA). NVX-207 bound to apolipoprotein A-I, a major regulator of lipid metabolism and cholesterol transport. A phase I/II study in dogs suffering from naturally occurring cancer receiving local treatment of NVX-207 (10 mg mL(-1)) showed excellent clinical responses including a complete remission in so far 5/5 treated animals. CONCLUSIONS: NVX-207 is well tolerated and has significant anti-cancer activity in vitro and in vivo in dogs with treatment-resistant malignancies.

Murine mobilized peripheral blood stem cells have a lower capacity than bone marrow to induce mixed chimerism and tolerance.

Allogeneic bone marrow transplantation (BMT) under costimulation blockade allows induction of mixed chimerism and tolerance without global T-cell depletion (TCD). The mildest such protocols without recipient cytoreduction, however, require clinically impracticable bone marrow (BM) doses. The successful use of mobilized peripheral blood stem cells (PBSC) instead of BM in such regimens would provide a substantial advance, allowing transplantation of higher doses of hematopoietic donor cells. We thus transplanted fully allogeneic murine granulocyte colony-stimulating factor (G-CSF) mobilized PBSC under costimulation blockade (anti-CD40L and CTLA4Ig). Unexpectedly, PBSC did not engraft, even when very high cell doses together with nonmyeloablative total body irradiation (TBI) were used. We show that, paradoxically, T cells contained in the donor PBSC triggered rejection of the transplanted donor cells. Rejection of donor BM was also triggered by the cotransplantation of unmanipulated donor T cells isolated from naïve (nonmobilized) donors. Donor-specific transfusion and transient immunosuppression prevented PBSC-triggered rejection and mixed chimerism and tolerance were achieved, but graft-versus-host disease (GVHD) occurred. The combination of in vivo TCD with costimulation blockade prevented rejection and GVHD. Thus, if allogeneic PBSC are transplanted instead of BM, costimulation blockade alone does not induce chimerism and tolerance without unacceptable GVHD-toxicity, and the addition of TCD is required for success.

Strong evidence for up-regulation of cyclooxygenase-1 in head and neck cancer.

BACKGROUND: Cyclooxygenase-1, in contrast to cyclooxygenase-2, is generally reported to be constitutively expressed as a housekeeping enzyme in many different tissues. A number of recently published reports, however, challenge the notion that cyclooxygenase-1 expression is invariably constitutive by demonstrating that this enzyme might be up-regulated under certain pathological conditions in, for example, breast or ovarian cancer cells. In this study we investigated the expression of cyclooxygenase-1 in head and neck tumours and compared it to the cyclooxygenase-1 expression levels in normal oropharyngeal epithelial cells. MATERIAL AND METHODS: Paraffin-embedded pretreatment biopsies were obtained from head and neck tumour patients (n = 35). In addition, samples of normal oropharyngeal mucosa were taken from patients (n = 12) undergoing routine tonsillectomy. Cyclooxygenase-1 expression levels were determined by immunohistochemistry, Western blotting and real-time RT-PCR in cancerous tissue versus normal mucosa. RESULTS: Immunohistochemistry revealed overexpression of cyclooxygenase-1 in tumour biopsies compared to normal mucosa. Cyclooxygenase-1 was highly synthesized in the cytoplasm of neoplastic cells while significantly lower levels were detectable in normal mucosal cells. Western blotting and real-time RT-PCR also demonstrated higher cyclooxygenase-1 levels in tumour specimens compared to normal tissue samples. CONCLUSION: In this study we show for the first time that cyclooxygenase-1 is overexpressed in head and neck cancer cells compared to epithelial cells of normal mucosa.

Challenging a dogma--surgery yields superior long-term results for T1a squamous cell carcinoma of the glottic larynx compared to radiotherapy.

AIMS: The aim of this study was to compare laser surgery, conventional endoscopic surgery and radiotherapy in the treatment of early T1a glottic cancer. METHODS: We conducted a retrospective analysis of patients with early vocal cord cancer (who underwent either conventional surgery via endoscopy or laryngofissur, or primary radiotherapy) at the Medical University of Vienna. By univariate and multivariate Cox regression models the influence of treatment and other parameters on survival and locoregional control were analysed. RESULTS: 337 Patients were analyzed with a mean follow-up period of 133.8 months. Overall survival rates where similar in all three treatment groups. Five-year, 10-year and 15-year estimates of disease specific survival for laser-treated patients were 100%, for conventional surgery were 100%, 98% and 98%, and for radiotherapy were 96%, 92% and 91%, respectively. Locoregional recurrences were observed after laser surgery in 10%, after conventional surgery in 13% and after radiotherapy in 30% of the patients treated. According to the log-rank test, time to relapse was significantly shorter for irradiated patients compared to patients who underwent surgery (p < 0.0001). Mortality caused by the laryngeal tumour was significantly higher in the radiotherapy group (p = 0.003). CONCLUSION: Patients undergoing laser or conventional surgery have a significantly lower incidence of locoregional recurrences and longer disease-free intervals when compared to patients treated by radiotherapy.

Validity of sentinel lymph node (SLN) detection following adjuvant radiochemotherapy (RCT) in head and neck squamous cell carcinoma (HNSCC).

The effect of preoperative radio chemotherapy on lymphatic drainage and intraoperative gamma probe-guided sentinel lymph node detection has yet not been investigated. In this study, we study 13 patients with SCC. Sentinel lymph node (SLN) imaging of the patients was performed using SPECT-CT. Special care was taken to use identical injection sites for both studies. Imaging comprised planar and SPECT, iterative reconstruction and were viewed with the co-registered CT image. The results were validated by comparison with the histological results of intraoperative gamma probe detection and histology of the completed neck dissection. Identical SLNs were found in 6/13 patients. In 2/13 cases SLN biopsies were false-negative. In 4/13 patients preoperative SLN imaging identified more/additional nodes than the initial imaging, whereas fewer nodes were seen in 3/13 patients. Neither the primary tumor site nor the TNM stage was predictive for changes in the lymphatic drainage pattern. No constant effect of irradiation could be demonstrated. Preoperative radio chemotherapy has an unpredictable influence on the lymphatic drainage pattern in HNSCC. Consequently, the intraoperative gamma probe-guided sentinel lymph node detection after radio chemotherapy does not reveal the SLN of carcinogenesis. Thus, we advise fused functional/anatomical imaging (SPECT-CT) before and after radiochemotherapy if the SLN concept is utilized in HNSCC.

Expression of the target receptor CD33 in CD34+/CD38-/CD123+ AML stem cells.

BACKGROUND: CD33 (Siglec-3) is becoming increasingly important as a target of antibody-mediated therapy in acute myeloid leukaemia (AML). In normal myelopoiesis, expression of CD33 is restricted to advanced stages of differentiation, whereas primitive stem cells do not express CD33. In the present study, we asked whether leukaemic stem cells in patients with AML express CD33. MATERIALS AND METHODS: A multicolour-staining technique was applied in 11 patients with AML, and leukaemic progenitors defined as CD34(+)/CD38(-)/CD123(+) cells. AML stem cells were purified by cell sorting and were examined for expression of CD33 mRNA by reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: In all patients in whom the majority of myeloblasts expressed CD33 (n = 8), AML progenitors reacted with the CD33 antibody P67.6. Repopulation experiments utilizing irradiated NOD/SCID mice confirmed that AML stem cells in these patients reside within the CD33(+) subpopulation of the leukaemic clone. Moreover, highly purified AML stem cells (> 98% purity) from patients with CD33(+) AML were found to express CD33 mRNA in RT-PCR analyses. CD33 was neither detectable on CD34(+)/CD38(-) cells in normal bone marrow nor on leukaemic stem cells in patients with CD33-negative AML. CONCLUSIONS: Leukaemic stem cells in patients with CD33(+) AML express CD33. This observation is in favour of novel treatment concepts employing CD33-targeting antibodies in AML.

Preoperative radiochemotherapy and radical resection for stages II to IV oral and oropharyngeal cancer: grade of regression as crucial prognostic factor.

The purpose of this study was to assess the prognostic value of histological response to preoperative radiochemotherapy in an established multimodal therapy concept for advanced oral and oropharyngeal cancer. Two hundred and twenty-two patients who underwent preoperative radiochemotherapy (RCT: 50 Gy, mitomycin C and fluorouracil) and radical surgery were retrospectively evaluated. Resected tumours of all patients were histologically analysed and response to RCT was classified in histopathological grades of regression (RG). In a multivariate statistical analysis, RG was compared with established factors regarding their predictive value for overall and disease-specific survival. The 5-year overall survival probability in the different groups of histopathological regression grades were: RG1 (no vital tumour): 73.4%, RG2 (minimal tumour remnants encompassing less than 5%): 72.1%, RG3 (5-50% vital tumour cells): 41.9%, RG4 (more than 50% vital tumour): 37.9%. For disease-specific survival probability no significant differences were found between both groups of "responders" (RG1 and RG2) nor between "non-responders" (RG3 and RG4), whereas responders and non-responders differed significantly from each other (log-rank test; p < 0.001). T-classification, N-classification and disease stage, histological grading, tumour site, age, and sex had less prognostic value than RG in a Cox regression model. In the neoadjuvant multimodal therapy concept, histological response to preoperative RCT is a crucial prognostic factor even when surgical R0-resection is accomplished. Thus, non-responders have to be regarded as high-risk patients for recurrence and may benefit from further therapy.

Preoperative radiochemotherapy and radical resection for stages II-IV oral and oropharyngeal cancer: outcome of 222 patients.

To analyse survival and locoregional control in patients with advanced oral and oropharyngeal squamous cell carcinoma (SCC) after multimodal therapy with preoperative radiochemotherapy (RCT) and radical surgery. We included in this analysis 222 patients who underwent multimodal therapy between 1990 and 2000. Eligible were patients with UICC disease stages II-IV (T2: 33.3%; T3: 12.6%; T4: 54.1%; N0: 45.9%; N1: 17.6%; N2: 33.3%; N3: 3.2%; stage II: 21.1%; stage III: 14.9%; stage IV: 64%). Patients received preoperative radiochemotherapy consisting of Mitomycin C (15-20 mg/m2, day 1) plus 5-Fluorouracil (750 mg/m2/24 h-infusion, days 1-5) and concomitant radiotherapy for a total dose of 50 Gy. Radical locoregional en bloc-resection according to the pretherapeutic tumour extension was carried out in all patients. After a median surveillance period of 72.3 months (24-152 months), 131 patients (59%) were alive, and 91 (41%) patients died; 12 (5%) of them died postoperatively, 46 (21%) due to tumour recurrence, and 33 (15%) deaths were not directly related to the primary tumour. Overall survival probability was 76% after 2 years, and 62% after 5 years. Two- and 5-year local control probability were 88 and 81%, respectively. Regarding the high percentage of stage IV disease in the reported patients, the multimodal concept is an effective therapy offering excellent survival and local control probability.

Hyperfractionated accelerated radiochemotherapy (HFA-RCT) with mitomycin C for advanced head and neck cancer.

To investigate efficacy and feasibility of hyperfractionated accelerated radiotherapy combined with mitomycin C, patients with locally advanced unresectable squamous cell carcinomas of the head and neck region were administered 64-66 Gy in four weeks and mitomycin C (20 mg/m(2)) on day five. Twenty-one consecutive patients were included between November 1997 and June 1999 (median age: 57 years). All tumours were stage T3-4 and 18/21 were N2-3. Eighteen patients experienced grade 3 and three patients grade 2 mucosal toxicity. With median follow up for surviving patients of 42 months, loco-regional control was 55% at three years, overall survival was 33% at three years. This treatment is at the edge of local tolerability, but there is a good curative chance even for very advanced localised tumours, provided a complete remission is induced at primary treatment.

On the way to targeted therapy of mast cell neoplasms: identification of molecular targets in neoplastic mast cells and evaluation of arising treatment concepts.

Several emerging treatment concepts for myeloid neoplasms are based on novel drugs targeting cell surface antigens, signalling pathways, or critical effector molecules. Systemic mastocytosis is a haematopoietic neoplasm that behaves as an indolent myeloproliferative disease in most patients, but can also present as aggressive disease or even as an acute leukaemia. In patients with aggressive disease or mast cell leukaemia, the response to conventional therapy is poor in most cases, and the prognosis is grave. Therefore, a number of attempts have been made to define novel treatment strategies for these patients. One promising approach may be to identify novel targets and to develop targeted drug therapies. In this article, we support the notion that neoplastic mast cells indeed express a number of potential molecular targets including immunoreactive CD antigens, the microphthalmia transcription factor (MITF), and members of the Bcl-2 family. In addition, the tyrosine kinase receptor KIT and downstream signalling pathways have been proposed as targets of a specific pharmacological intervention. A particular challenge is the disease-related D816V-mutated variant of KIT, which is resistant against diverse tyrosine kinase inhibitors including STI571, but may be sensitive to more recently developed targeted compounds. The therapeutic potential of target-specific approaches in malignant mast cell disorders should be evaluated in forthcoming clinical trials in the near future.

The early response of p53-dependent proteins during radiotherapy in human rectal carcinoma and in adjacent normal tissue.

The aim of this study was to investigate the activation of the p53 pathway and the induction of apoptosis during preoperative radiotherapy in normal human rectal tissue and in rectal carcinoma. Twelve patients with rectal cancer of the lower third were enrolled in this study. Tumor specimens and adjacent normal tissue were obtained before radiation, after the third radiation cycle and from the surgically removed rectum. All specimens were analyzed be means of immunohistochemistry for expression of p53 and its downstream target genes MDM2 and p21. In normal mucosal crypts, irradiation led to p53 accumulation and MDM2 induction in more than 70% of the cells. The accumulation of p53 in basal crypts was associated with high expression of p21. Apoptosis was also induced in crypts and occurred in 15% of the cells. Activation of the p53 pathway was not seen in the resting cells at the luminal border of the epithelium. In interstitial cells, p21 was highly upregulated, whereas p53 and MDM2 showed weak expression. The level of bcl-2 was not altered during radiotherapy in healthy tissue. In rectal carcinoma cells, p53 expression was unaltered by irradiation in 11 out of 12 tumors. The p53 non-functional tumors were characterized by a weak induction of MDM2 and p21 and by the lack of apoptosis in the presence of bcl-2. Our findings demonstrate that sequential immunohistochemical analysis is suitable to detect a deregulation of the p53 pathway in human rectal cancer cells during radiotherapy. Further investigations are necessary to elucidate its value as a prognostic marker and potential predictor of therapy responsiveness.

Bcl-x(L) antisense oligonucleotides radiosensitise colon cancer cells.

Advanced colon cancer is a malignancy with poor response to various treatment modalities including ionising radiation (IR) and chemotherapy. Both IR and chemotherapeutic agents have been shown to act by inducing apoptosis, a type of cell death antagonised by the Bcl-x(L) gene product. Since approximately 60% of human colon cancers express Bcl-x(L), it was the aim of this study to explore the potential of Bcl-x(L) antisense oligonucleotides as a novel radiosensitisation strategy. Caco-2 colon cancer cells were treated with Bcl-x(L) antisense oligonucleotides in combination with IR or cisplatin, and Bcl-x(L) protein expression, apoptosis, cell viability and clonogenic survival were examined. Bcl-x(L) antisense oligonucleotide specifically reduced the Bcl-x(L) protein level by almost 50% in Caco-2 cells. The decreased threshold for the induction of apoptosis resulted in a 300% increase of apoptosis after IR or cisplatin treatment and led to a 60% reduction of cell proliferation beyond response rates achieved with IR. These data suggest that Bcl-x(L) is an important factor contributing to the treatment resistance of human colon cancer. Specific reduction of Bcl-x(L) protein levels by antisense oligonucleotides qualifies as a promising therapeutic strategy for colon cancer that may help overcome resistance and improve clinical outcome in this malignancy.

Phase II study with docetaxel and cisplatin in the treatment of recurrent and/or metastatic squamous cell carcinoma of the head and neck.

PURPOSE: Since the combination of cisplatin and docetaxel have demonstrated activity in squamous cell carcinomas of the lung and oesophagus before, promising results in recurrent metastatic head and neck cancer were expected. PATIENTS AND METHODS: Between September 1998 and October 2000, 40 patients entered this trial, 38 of whom were evaluable. Six patients were previously untreated, 24 had surgery and/or radiotherapy and 13 had received chemoradiation and/or surgery. Therapy consisted of 75 mg/m(2) docetaxel (1-hour infusion) and 75 mg/m(2) cisplatin (90-min infusion) on day 1, repeated every three weeks for a maximum of 6 courses. All patients received corticosteroids routinely, 5-HT3-antagonists, and hydration. RESULTS: The overall response rate was 52.5% (95% confidence interval, 36.1 to 68.5%) including 7 complete (17.5% complete response; CR) and 14 partial remissions (35% partial response; PR). The overall response rate in patients who had no prior treatment (n = 6) was 100%, including 3 CR and 3 PR. In patients who had prior surgery and/or radiotherapy (n = 21) an overall response rate of 42.8% was observed, including 2 CR and 7 PR; 8 patients (38.1%) had stable disease, while disease progressed in 3 (14.3%). Six of 13 patients (46.2%) who had prior chemoradiation +/- surgery responded, including 2 CR (15.4%) and 4 PR (30.8%), no change was seen in 4 patients (30.8%) and tumour progressed in 2 (15.4%). The median response duration for all patients was 10 months (range, 3-20), the median overall survival was 11 months (range, 1-30). Myelosuppression was commonly observed; WHO grade 3 or 4 neutropenia occurred in 12 patients (30%) each, and was complicated by septicaemia in 5 cases. WHO grade 3 anaemia was observed in only 3 patients (7.5%). Severe non-hematologic toxicity except for alopecia was rarely observed, and included diarrhea in 2 (5%), nausea/vomiting in 2 patients (5%) and stomatitis in 1 patient (2.5%). CONCLUSION: Our data suggest that docetaxel and cisplatin in combination is an effective and fairly well tolerated regimen for the treatment of head and neck cancer with an excellent response rate in previously untreated patients.

Protein kinase C isoforms in normal and transformed cells of the melanocytic lineage.

Enzymes belonging to the protein kinase C (PKC) family represent one of the major mediators of signal transduction in melanocytes. To identify PKC isoforms that may be associated with the process of malignant transformation and metastasis, we investigated the expression pattern of 11 different PKC isoforms (alpha, beta I, beta II, gamma, delta, epsilon, eta, theta, zeta, lambda, and iota) in melanoma lymph node metastases, in cell lines established from these metastases, in primary cell cultures from normal melanocytes, and in permanent cell lines established from spontaneously transformed melanocytes. PKC alpha, beta I, beta II, delta, epsilon, eta, zeta, lambda and iota were found to be expressed in total lysates from melanoma metastases. In permanent cell lines established from these metastases, the expression levels of PKC beta I, beta II, delta, epsilon, and eta were lower or undetectable when compared with initial expression in tumour lysates. In normal primary melanocyte cultures, the PKC isoforms beta II, delta, epsilon, eta and iota were undetectable. PKC gamma and theta isoforms were undetectable in all melanocytic cell types examined. PKC iota was the only isoform exclusively detected in tumour lysates, in spontaneously transformed melanoma cells and melanoma cell lines, but not in normal melanocytes, and may therefore be associated with the transformed phenotype in human melanoma in vitro and in vivo.

Effects of irradiation on 99m Tc sestamibi and 201Tl uptake in a human papillary thyroid carcinoma cell line.

Both 99mTc sestamibi and 201Tl have been used in conjunction with 131I scintigraphy for follow-up of patients with thyroid cancer. The aim of the study was to determine if irradiation affects tracer uptake in papillary thyroid cancer cells. The human papillary carcinoma cell line (PAP/ES-1) used in this study was generated from a papillary thyroid tumour obtained after surgery. For the in vitro uptake studies cells were seeded at 2 x 105 cells/well into 12-well microtitre plates. Irradiation was performed with a 60Co source (total dose, 2 Gy and 10 Gy). After incubation at 37 degrees C the supernatants were saved for determination of the unincorporated activity. The reaction was stopped by washing the cells four times in ice cold phosphate buffered saline. Total cellular uptake was determined by measuring cell lysate radioactivity in a Compugammasystem and was expressed as per cent uptake per mg of total cellular protein. At continuous incubation 201Tl uptake was significantly (P<0.01) higher after radiation whereas no effect of irradiation was found on 99mTc sestamibi uptake. Pulsed experiments revealed that irradiated cells displayed a faster 201Tl efflux. The net tracer retention at 90 min was similar to 201Tl to that of 99mTc sestamibi. We conclude that 99mTc sestamibi kinetics in thyroid cancer are not affected by irradiation and may therefore be superior to 201Tl in the follow-up of thyroid cancer shortly after radiotherapy.