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.

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.

[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.

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.

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.

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.

Effects of betulinic acid alone and in combination with irradiation in human melanoma cells.

Recently, betulinic acid was identified as a highly selective inhibitor of human melanoma growth and was reported to induce apoptosis in these cells. We have investigated the growth-inhibitory properties of this compound alone and in combination with ionizing radiation in a panel of established human melanoma cell lines as well as in normal human melanocytes. Betulinic acid strongly and consistently suppressed the growth and colony-forming ability of all human melanoma cell lines investigated. In combination with ionizing radiation the effect of betulinic acid on growth inhibition was additive in colony-forming assays. Betulinic acid also induced apoptosis in human melanoma cells as demonstrated by Annexin V binding and by the emergence of cells with apoptotic morphology. The growth-inhibitory action of betulinic acid was more pronounced in human melanoma cell lines than in normal human melanocytes. Notably, despite the induction of apoptosis, analysis of the expression of Bcl-2 family members in betulinic-acid-treated cells revealed that expression of the anti-apoptotic protein Mcl-1 was induced. Furthermore, the antiproliferative action of betulinic acid seemed to be independent of the p53 status. The properties of betulinic acid make it an interesting candidate, not only as a single agent but also in combination with radiotherapy. We conclude that the strictly additive mode of growth inhibition in combination with irradiation suggests that the two treatment modalities may function by inducing different cell death pathways or by affecting different target cell populations.

Impact of hemoglobin level and use of recombinant erythropoietin on efficacy of preoperative chemoradiation therapy for squamous cell carcinoma of the oral cavity and oropharynx.

PURPOSE: We assessed the influence of hemoglobin level and r-HuEPO administration on response to chemoradiotherapy, locoregional tumor control, and overall survival in patients treated with neoadjuvant chemoradiotherapy and surgery for a squamous cell carcinoma of the oral cavity or oropharynx. METHODS AND MATERIALS: The 191 study patients were treated with mitomycin C (15 mg/m(2) day 1), 5-fluorouracil (750 mg/m(2)/day, days 1-5), and radiotherapy (50 Gy in 25 fractions weeks 1-5), followed by resection of the primary tumor bed and neck dissection at the General Hospital Vienna, Austria, between November 1989 and October 1998 for a T2-4, N0-3, M0 SCC of the oral cavity or oropharynx. Starting in May 1996, patients with a low hemoglobin (Hgb) before or during chemoradiotherapy received r-HuEPO 10,000 IU/kg s.c. 3-6 times/week until the week of surgery. RESULTS: On multivariate analysis, Hgb level and use of r-HuEPO were independent prognostic factors for response to chemoradiotherapy and locoregional tumor control (p < 0.01). Pathologic response to neoadjuvant therapy was also predictive of locoregional control (p < 0.001). Patients with a pretreatment Hgb > or = 14.5 g/dL had significantly higher complete response, locoregional control, and survival rates than the patients with a pretreatment Hgb < 14.5 g/dL who did not receive r-HuEPO (p < 0.05). The response, control, and survival rates in patients with a pretreatment Hgb < 14.5 g/dL given r-HuEPO were significantly higher than in low Hgb patients not given r-HuEPO (p < or = 0.001) and equivalent to patients with a pretreatment Hgb > 14.5 g/dL (p > or = 0.3). CONCLUSION: Low pretreatment Hgb is a negative prognostic factor for oral cavity and oropharyngeal SCCA patients, but was completely abrogated by r-HuEpo administration during neoadjuvant chemoradiotherapy. Randomized trials of radiation and/or chemotherapy with or without r-HuEPO for patients whose Hgb level is either low at the start of therapy or is anticipated to become low during therapy are indicated.

Combined radiochemotherapy of locally advanced unresectable pancreatic adenocarcinoma with mitomycin C plus 24-hour continuous infusional gemcitabine.

BACKGROUND: In locally advanced pancreatic cancer, the combination of chemotherapy with radiotherapy is gaining increasing importance; although, in view of the reported long-term results of several contemporary trials, further improvements are certainly warranted. The aim of the present study was to evaluate the effectiveness and safety of a combined-treatment modality consisting of systemic chemotherapy with 24-h continuous infusional gemcitabine and mitomycin C, plus external beam radiotherapy in patients with localized unresectable adenocarcinoma of the pancreas. METHODS AND MATERIALS: Systemic chemotherapy consisted of mitomycin C 8 mg/m2 given as i.v. bolus injection on day 1 and gemcitabine administered as a 24-h continous infusion once weekly for 3 of 4 weeks. The starting dose of gemcitabine was 100 mg/m2 and dose levels were escalated in consecutive cohorts of 3-6 patients to 130 and 160 mg/m2, utilizing an escalating-dose Phase I trial design. Radiation therapy using megavolt irradiation (total dose, 45 Gy, 1.8 Gy/day) of 6 MV photons or greater with a 3- or 4-field technique was delivered concurrently for 5-6 weeks. RESULTS: Between January 1997 and August 1998, a total of 15 patients were enrolled in this trial, all of whom were assessable for toxicity, response, and survival. The dose-limiting toxicities at the 160 mg/m2 gemcitabine level were myelosuppression, specifically neutropenia +/- thrombocytopenia, and gastrointestinal symptoms, including stomatitis, vomiting, and diarrhea. Only 1 partial response was observed (7%), and disease was stabilized in 10 additional patients (67%). The median time to progression was 5.5 months (range, 2-12 months). Whereas all patients developed distant metastases, locoregional failure occurred in only 3. The median survival time was 8.3 months (range, 2.5 to 22.0+ months), and the 1-year survival rate was 13.3%. CONCLUSION: The MTD of gemcitabine when given as prolonged infusion in combination with mitomycin C and radiation therapy was 130 mg/m2/week. Therapeutic results suggest that combined chemoradiation with this regimen is feasible and effective for local control of pancreatic cancer, but essentially ineffective in counteracting metastatic tumor growth.

Suramin affects differentiated and undifferentiated human thyroid epithelial cells in vitro.

In the last decade, suramin has become known for its antiproliferative, differentiation-inducing effects on cells and has been successfully used in the therapy of cancer patients. The present study was undertaken to investigate the effects of suramin on normal human thyroid cells in primary monolayer culture and to analyse whether it also affected cells from thyroid carcinomas. The results show that suramin, at concentrations similar to serum levels obtainable during therapy, inhibited the proliferation of thyroid cells as well as the secretion of thyroglobulin. It suppressed the activation of adenylyl cyclase in thyroid membranes and decreased the immunogenicity of the cells by reducing their surface expression of HLA-DR and ICAM-1. Although the morphology of differentiated thyroid cells remained unaffected by suramin, morphological changes compatible with differentiation were observed in cells from undifferentiated thyroid carcinomas when suramin was added to the culture medium. In conclusion, the data demonstrate that suramin has pronounced in-vitro effects on normal and neoplastic thyroid cells. It may, therefore, also be effective in patients with thyroid cancer, for whom no other form of treatment is available.

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.

Intratumoral pO2-measurements as predictive assay in the treatment of carcinoma of the uterine cervix.

BACKGROUND: Several studies have shown that pretreatment oxygenation status of cervical tumors measured with a polarographic oxygen electrode could be a predictive factor for radiation response and survival. The purpose of this study was to evaluate the impact of intratumoral pO2 levels and hypoxic fractions on local control and disease free survival employing a standardized measuring procedure under routine conditions. MATERIALS AND METHODS: Between April 1994 and December 1997 pO2 measurements were performed prior to radiotherapy with an Eppendorf histograph in 51 evaluable patients with primary cervical carcinoma. All patients were treated with curative intent by combined external beam therapy (median total dose 49.6 Gy) and 3-6 applications of high dose rate- (7 Gy/fr. at point 'A') or pulse dose rate brachytherapy (20-25 h pulses, 1 Gy/pulse at point 'A'). Oxygenation data are given as median pO2 of pooled readings and percentage of readings below 5 mm Hg (HF 5). RESULTS: Median pO2 values ranged from 0 to 60 mm Hg (median 10). HF5 ranged from 0 to 95% (median 22%). Median follow-up was 26 months (range 9-54 months). Actuarial overall and disease-free survival rates (OS/DFS) at 3 years were 53%/50%. Comparing patients with median pO2 < or = 10 mm Hg (n = 26) to patients with higher median pO2 levels (n = 25) calculated DFS was 34 and 69%, respectively (P < 0.02). Corresponding data for local control were 47 and 84% (P = 0.053). Comparing patients with HF5 below and above the median calculated DFS was 36 and 66%, respectively (P < 0.02). Patients who had median pO2 < 10 mm Hg and HF5 > 20% had the worst prognosis (3-year DFS: 28%). Besides oxygenation status, stage and initial hemoglobin concentration were statistically significant for treatment outcome. CONCLUSIONS: This study confirms earlier data that the presence of hypoxia is associated with poor local control and survival in patients with carcinoma of the uterine cervix. Polarographic pO2 measurements are feasible under routine conditions and can be regarded as a reproducible predictive assay.

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.

Effects of type I-interferons on human thyroid epithelial cells derived from normal and tumour tissue.

Long term interferon (IFN) therapy is frequently associated with side effects which affect the thyroid gland such as hypothyroidism and thyroiditis. We have therefore tested the ability of type I-IFNs to exert direct effects on primary cultures of human thyroid epithelial cells: (i) Type I-IFNs (IFN-alpha 2b and IFN-omega) inhibit cell proliferation as determined by [3H]thymidine incorporation with a half-maximal effect at approximately 1 ng/ml (50 pM). Inhibition of cell growth is observed in cells derived from normal thyroid as well as neoplastic tissue (autonomous and non-secreting adenoma; follicular, papillary and anaplastic carcinoma). (ii) Over a similar concentration range, type I-IFNs suppressed thyroglobulin release by thyroid cells. (iii) IFN-alpha 2b stimulated surface expression of major histocompatibility class (MHC) I but not MHC II molecules, while IFN-gamma enhanced the expression of both MHC I and MHC II molecules. This effect of IFN-gamma, but not that of IFN-alpha 2b was antagonized by suramin. (iv) Incubation of thyroid cells with IFN-alpha 2b also resulted in increased cell surface levels of the intercellular adhesion molecule 1 (ICAM-1). These findings demonstrate that type I-IFNs directly affect thyroid function and explain related side effects of these cytokines. In addition, our results provide a rational basis for the possible use of type I-IFNs in the treatment of patients with advanced thyroid cancer for whom no therapeutic alternative exists.

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.