Chemotherapy with paclitaxel and gemcitabine in progressive medullary and thyroid carcinoma of the follicular epithelium

Nine patients (mean age 53) with metastasizing, progressive, medullary (MTC), thyroid carcinoma and progressive, nonradioiodine accumulating thyroid carcinoma of the follicular epithelium (follicular carcinoma, FTC and papillary carcinoma, PTC) were treated with a combination of paclitaxel and gemcitabine between 2004 and 2006. Tumors were histologically classified as follicular in 5 patients (56%), as papillary in 2 patients (22%), and medullary in 2 patients (22%). Paclitaxel (90-100 mg/m (2)) and gemcitabine (1,000 mg/m (2)) were applied for two, three, or 6 cycles every three weeks, depending on response and side effects. The effect of therapy was evaluated by radiographic imaging (CT images) and [(18)F]FDG-PET. All patients with papillary, follicular, or medullary thyroid carcinoma had continuous progression during restaging 14.8+/-8.8 weeks after initiation of chemotherapy, including one patient with stable disease after 3 cycles, but continuous progression after 6 cycles of chemotherapy. Paclitaxel and gemcitabine are not a valid chemotherapy option, in particular in patients with progressive, nonradioiodine-accumulating follicular thyroid carcinoma, who were already treated by other chemotherapeutic agents.

Activity of mTOR-Inhibitor Rad001 (everolimus) in differentiated and anaplastic thyroid cancer cell lines

e14608

Background: Recent data suggest that aberrant activation of PIK3/AKT-pathway and mTOR are involved in the development of thyroid cancer, particularly of anaplastic (ATC) and follicular (FTC) subtype. Therefore, mTOR could be a potential treatment target in thyroid cancer. Methods: To asses the potential role of mTOR as target for the treatment of thyroid cancer, two human ATC cell lines SW1736 and 8505C, the papillary thyroid cancer (PTC) cell line BCPAP and the FTC cell line FTC133 were exposed for 96h to increasing concentrations of the mTOR inhibitor RAD001 (Everolimus, kindly provided by Novartis, Switzerland). For combination experiments 10 nM of RAD001 were combined with increasing concentrations of either doxorubicin (DOX) or cisplatin (CDDP) continuously. Cytotoxicity was measured using the sulforhodamine B assay. IC50-values were calculated with Sigma Plot (Jandel Scientific) and drug interaction was determined by the model of Drewinko. Results: The observed IC50-values of RAD001 were 1nM (FTC133), 10 nM (BCPAP), 1000 nM (SW1736) and 9400 nM (8505C). In contrast to the pronounced differences in sensitivity as assessed on the basis of IC50, a growth inhibitory effect ≥ 25 % was seen in all cell lines at a concentration of 1 nM of RAD001. IC50 for CDDP ranged from 1,3–4,8 μM and for DOX from 8–40 nM. Combination of 10 nM RAD001 with either DOX or CDDP resulted in additive drug interaction with the exception in cell line 8505C where significant synergy was found for the combination with CDDP. Conclusion: RAD001 exerted interesting preclinical activity in two differentiated thyroid cancer cell lines. Mainly additive drug interaction in thyroid cancer cell lines was observed for combinations with CDDP and DOX. Mechanistic investigations are underway and will be presented at the meeting. At least for differentiated thyroid cancer mTOR-inhibition appeared promising, further evaluation in thyroid cancer seems warranted.

No significant financial relationships to disclose.

Safety and efficacy of a triple antiemetic combination with the NK-1 antagonist aprepitant (APR) in high (HEC), moderate (MEC) and high dose chemotherapy (HDC) in multiple day chemotherapy (MDC)

19545

Background: 5-HT3 receptor antagonists (RA) plus dexamethasone (DEX) has been shown to induce 55–57% complete responses from emesis during the 4–5 days of cisplatin chemotherapy. The role of aprepitant in MDC remains to be defined. The antiemetic triple combination of a NK-1-RA, 5-HT3-RA and dexamethasone has not been formally investigated in more than one day chemotherapy. Methods: In this retrospective study, pts. with MDC received APR 125 mg d1, 80 mg consecutive days, granisetron (GRAN) 2 mg daily and DEX 8 mg daily for prevention of acute CINV and APR 80 mg and DEX 8 mg for 2 days for delayed CINV. Endpoints were complete response (CR, no vomiting & no use of rescue therapy) in the acute, delayed and overall phase. Results: Of 103 pts. (f/m 21/82 pts.; median age 40.6y) with various types of cancers 41 pts. (39.8%) received HEC, 44 (42.8%) MEC, and 18 pts. (17.4%) HDC. Median duration of CTX was 3.42 days (HEC 3.9 d). The most frequent regimens were ICE (35%), PEB (14.6%), I3VA (10.7%), MAID (4.9%) and IEV (5.9%). Toxicity: Singultus was reported in 6.8% and loss of appetite in 25.5%. Elevation (CTC grade 1–2) of transaminase/AP/bilirubin and creatinine were seen in comparison to pretreatment values in 15.6%/6.8%/21.1% and 7.8% of all pts.. Efficacy: Acute/delayed/overall CR in HEC was 68.3%/70.7%/63.4%, in MEC 77.3%/84.1%/77.3% and in HDC 77.8%/61.6%/55.6%. Risk factor analysis revealed that pretreatment anxiety increased the risk of vomiting significantly (p= 0.008). Conclusions: Toxicity seems not to be increased by the multiple day treatment of APR (5–7 days) in comparison to the usually used 3-day APR regimen. The CR in the acute and delayed phase in patients receiving HEC was superior to the results reported in the literature with the combination of a 5-HT3 RA and DEX. The CR in the delayed phase in MEC was better than reported by Warr et al. where pts. receiving only one day of MEC and APR mono in the delayed phase. This might be due to the combination of APR/DEX in the delayed phase in our study. These promising results have to be confirmed in a prospective randomized trial.

No significant financial relationships to disclose.

A meta-analysis comparing the efficacy of four 5-HT3-receptor antagonists for acute chemotherapy-induced emesis

GOALS OF WORK

Comparing antiemetic efficacy of different 5-HT(3)-receptor antagonists (5-HT(3)RAs) is difficult due to inter-study variability. Therefore, a meta-analysis was performed to comparatively evaluate dolasetron, granisetron, ondansetron and tropisetron for acute chemotherapy-induced nausea and vomiting (CINV).

PATIENTS AND METHODS

Comparisons between 5-HT(3)RAs were based on 44 randomized studies (including 12,343 patients) identified by MEDLINE, CANCERLIT or EMBASE searches and subcategorized by chemotherapy type (cisplatin- or non-cisplatin-based).

MAIN RESULTS

When all studies were combined, granisetron was equivalent to ondansetron (n = 27), and showed an advantage vs tropisetron (p = 0.018; n = 12). Ondansetron vs tropisetron (n = 11) and ondansetron vs dolasetron (n = 3) revealed equivalence in each comparison. An advantage for 3 mg granisetron vs 8 mg ondansetron was found in non-cisplatin-based studies (p = 0.015; n = 6). Overall equivalence was seen between ondansetron, 24 or 32 mg, and granisetron, 2 or 3 mg, for all studies (n = 13). There was a possible advantage for higher (24 or 32 mg) vs lower (8 mg) ondansetron dose regimens with cisplatin-based trials (n = 6). No differences were seen between 3 and 1 mg granisetron doses (n = 6).

CONCLUSIONS

Efficacy of 5-HT(3)RAs for preventing CINV following cisplatin- and non-cisplatin-based chemotherapy is comparable, with the exception of granisetron vs tropisetron. Some differences were noted in dosing subanalyses.

[Chemotherapy induced-vomiting--a practical guide for prevention and therapy]

Nausea and vomiting are considered as two of the most distressing side effects of chemotherapy. The frequency of nausea and vomiting depends primarily on the emetogenic potential of the chemotherapeutic agents used. With the introduction of the neurokinin-1-receptor-antagonists in combination with 5-HT(3) receptor-antagonists and steroid approximately 70-90 % of patients receiving highly emetogenic chemotherapy can be protected from emesis. Here, the most recent developments in the antiemetic therapy including the latest guidelines for antiemetic prophylaxis are described.

Enterobacterial autoinducer of growth enhances shiga toxin production by enterohemorrhagic Escherichia coli

The addition of the enterobacterial autoinducer of growth to nutrient-poor minimal medium markedly accelerated the exponential growth rates of strains of enterohemorrhagic Escherichia coli but had little or no effect on maximal cell densities in stationary phase. Growth in the presence of the autoinducer resulted in an approximately twofold enhancement in Shiga toxin production.

C-reactive protein is a strong independent predictor of death in type 2 diabetes: association with multiple facets of the metabolic syndrome

INTRODUCTION

It has been suggested that atherosclerotic vascular disease is a chronic inflammatory process. The aim of this study was to investigate the importance of C-reactive protein (CRP) as a cardiovascular risk marker and predictor of death, as well as its relation to other factors of the metabolic syndrome in a cohort of type 2 diabetic patients at high risk of severe macrovascular complications.

MATERIAL AND METHODS

592 patients, aged 55 to 74 years (311 men, 281 women), with signs and symptoms of circulation deficits were examined by duplex ultrasound for suspected cerebrovascular and peripheral arterial disease and followed over a period of 5 years. At baseline, 292 patients of the total group had type 2 diabetes (49.3%). Ischemic heart disease was present in 40.2%, internal carotid stenosis in 21.9% and peripheral arterial disease in 39.7% of the subjects.

RESULTS

During the observation period, 104 patients had died, 72 (69.2%) due to cardiovascular causes. Non-fatal myocardial infarction occurred in 39 patients (7.4%), non-fatal stroke in 70 patients (13.3%) and amputations because of gangrene were unavoidable in 24 patients (4.6%). In Cox regression analysis, CRP was the strongest predictor of death and cardiovascular death in the total cohort (RR 3.7 [95% CI 1.86-7.50] and 5.4 [2.13-13.76]), as well as in the type 2 diabetic subgroup (RR 3.3 [1.27-8.70] and 5.4 [1.44-20.0]). In contrast neither the traditional cardiovascular risk factors nor the data of diabetic metabolic control were able to improve prediction. CRP was correlated positively with plasma levels of triglycerides (r=0.19, p=0.002), C-peptide (r=0.21, p=0.004), postprandial glucose (r=0.17, p=0.009), albuminuria (r=0.16, p=0.020), and inversely with HDL cholesterol (r=-0.20, p=0.002) in type 2 diabetic patients.

CONCLUSIONS

CRP seems to be a better predictor of death and cardiovascular events than traditional risk factors or parameters of metabolic control in type 2 diabetic patients at high risk for cardiovascular endpoints. Additionally, CRP is associated with several facets of the metabolic syndrome.

Potential activity of paclitaxel, vinorelbine and gemcitabine in anaplastic thyroid carcinoma

Anaplastic thyroid carcinoma (ATC) has a rapidly fatal course in the mostly elderly patients with a median survival after diagnosis of 4-12 months. Activity of commonly used chemotherapy (doxorubicin) is low, thus more active compounds need to be introduced into the therapeutic concept of ATC. Recently, based on preclinical data Ain et al. conducted a clinical phase II study with paclitaxel 96 h infusion in ATC achieving a promising response rate of 53%. To further improve therapeutic options in ATC, we evaluated the activity of topotecan, oxaliplatin, vinorelbine, gemcitabine and paclitaxel in comparision to cisplatin and doxorubicin (1 and 96 h drug exposure) alone or in combination in the ATC cell lines SW1736 and 8505C. IC50 values were determined by the sulforhodamine B assay, potential clinical activity was estimated by relative antitumor activity (RAA) and drug interaction was analyzed using a parametric response surface approach (Greco model) of the Loewe additivity. Duration of drug effect was estimated by regrowth kinetics. We found paclitaxel, vinorelbine and gemcitabine active in ATC with RAA (1 h drug exposure) ranging from 86 to 454, 15 to 17 and 31 to 140, respectively. The activity of doxorubicin and cisplatin was moderate with RAA ranging from 1.4 to 2.2 and 0.2 to 0.3, respectively. Combined drug exposure of gemcitabine/paclitaxel and gemcitabine/vinorelbine was synergistic with a Loewe index > 0. However, these results did not reach statistical significance with p > 0.05. At clinically relevant drug concentrations paclitaxel, gemcitabine and vinorelbine but not oxaliplatin exerted a sustained growth inhibition after cessation of drug exposure for the complete assay time of 15 days. In conclusion, paclitaxel, gemcitabine and vinorelbine but not topotecan or oxaliplatin appeared to be active in anaplastic thyroid carcinoma based on RAA or growth delay at clinically relevant drug concentrations. Combinations of vinorelbine/gemcitabine and paclitaxel/gemcitabine exerted a trend to synergy. Thus, further evaluation of paclitaxel, vinorelbine and gemcitabine alone or in combination with ATC seems warranted.

Catecholate receptor proteins in Salmonella enterica: role in virulence and implications for vaccine development

Three outer membrane proteins of Salmonella enterica serovar Typhimurium function as catecholate siderophore receptors. IroN promotes uptake of enterobactin, salmochelins and 2,3-dihydroxybenzoylserine, FepA transports enterobactin and 2,3-dihydroxybenzoylserine, and Cir is a receptor for 2,3-dihydroxybenzoylserine. In addition, all three proteins are required for l-norepinephrine-facilitated iron uptake from transferrin as judged by failure of a fepA iroN cir triple mutant to grow in serum-containing medium in the presence of l-norepinephrine. Moreover, pre-treatment of mice with l-norepinephrine resulted in enhanced systemic spread of the parental strain, but had no effect on the fepA iroN cir mutant. Inoculation of mice with the triple mutant, which is significantly attenuated, elicited a significant protective effect against subsequent challenge with the parental strain.

Role of receptor proteins for enterobactin and 2,3-dihydroxybenzoylserine in virulence of Salmonella enterica

Single, double, and triple mutants of an enterobactin-deficient mutant strain of Salmonella enterica serovar Typhimurium were constructed that were defective in the expression of the iron-regulated outer membrane proteins (IROMPs) FepA, IroN, and Cir, which are proposed to function as catecholate receptors. Uptake of naturally occurring and chemically synthesized catecholate molecules by these mutants was assessed in standard growth promotion assays. Unique patterns of uptake were identified for each IROMP; specifically, FepA and IroN were confirmed to be required for transport of enterobactin, and all three proteins were shown to function as receptors for the enterobactin breakdown product 2,3-dihydroxybenzoylserine. The fepA, iroN, and cir alleles were transduced to enterobactin-proficient strains of S. enterica serovar Typhimurium and S. enterica serovar Enteritidis, and the resulting phenotypes were confirmed by analysis of outer membrane protein profiles, by sensitivity to KP-736, a catecholate-cephalosporin conjugate, and by growth promotion tests on egg white agar. Intragastric infections of mice with the S. enterica serovar Typhimurium strains indicated that the parental strain and the fepA iroN double mutant were similarly virulent but that the fepA iroN cir triple mutant was significantly attenuated. Moreover, in mixed infections, the fepA iroN mutant showed similar cecal colonization and invasion of the liver to the parental strain, while the triple mutant showed significantly reduced cecal colonization and no measurable spread to the liver. Infections of 4-day-old chicks with S. enterica serovar Enteritidis strains also indicated that mutation of the fepA iroN genes did not significantly reduce cecal colonization and systemic spread compared with those of the parental strain. The results indicate that, while enterobactin uptake is not essential for the virulence of S. enterica serovars in mouse and chicken infection models, the ability to take up 2,3-dihydroxybenzoylserine via any of the three catecholate siderophore receptors appears to play an important role, since the S. enterica serovar Typhimurium triple mutant was significantly attenuated in the mouse model. Salmochelins appear not to be involved in the virulence of S. enterica.

Clonal diversity of Shiga toxin-producing Escherichia coli O103:H2/H(-) in Germany

Shiga toxin producing Escherichia coli O103:H2/H(-) belong to the third most frequently isolated EHEC serotypes in Germany following isolates of O157:H7/H(-) and O26:H11/H(-). A total of 145 respective E. coli 103 isolates from single cases of diarrhoea and haemolytic uremic syndrome (HUS) in 1997-2000 were characterised by a range of molecular subtyping methods (PFGE, P-gene profiling, ribotyping, electrotyping) and phage typing in order to analyse their genetic relatedness and the practicability for new epidemiological tracing back. All isolates cluster into a distinct EHEC subgroup and reveal a high clonal diversity together with a considerable stability. Since strains of this serotype rank up to the third most frequently isolated EHEC in Germany a large population of this serotype, and therefore, a great supply of such strains may exist in this country.

A new chemoembolization protocol in refractory liver metastasis of colorectal cancer--a feasibility study

INTRODUCTION

In patients with advanced colorectal cancer (CRC) refractory to systemic chemotherapy including 5-fluorouracil (5-FU) / folinic acid (FA), oxaliplatin and irinotecan we assessed the feasibility, toxicity and response to hepatic transcatheter arterial chemoembolization (TACE). At the time of treatment, patients had exclusively or dominantly liver metastasis of CRC.

PATIENTS AND METHODS

The following protocol was applied via a selective transfemoral hepatic arterial approach: mitomycin C 5 mg/m(2), interferon-alpha2b 4.5 Mio IU, dexamethasone 20 mg mixed with Amilomer DSM 45/25 (Spherex((R))) days 1 and 2 i.a. (bolus), oxaliplatin 50 mg/m(2) (2 h) day 1 i.a., FA 500 mg/m(2) (2 h) day 1 i.v., and 5-FU 1.500 mg/m(2) (24 h) day 1 i.a. Cycles have been repeated at days 15-22. The dose was adjusted according to the pretreatment performance status and elevation of alkaline phosphatase, bilirubin and serum albumin. Treatment was continued until progression or emergence of intolerable toxicity.

RESULTS

11 patients received a total number of 43 TACE, with a range of 2-6 per patient. There was no TACE-related mortality. 4 patients died 5, 8, 10 and 11 months after initiation of treatment due to progression of disease. 7 patients are alive at 4+ (n = 2), 5+ (n = 1), 6+ (n = 1), 7+ (n = 1) and 11+ (n = 2) months after start of treatment. Toxicity (CTC) was mild with grade I-II asthenia (n = 10), grade I-II neurotoxicity (n = 5), grade II nausea and/or vomiting (n = 2) and grade II diarrhea (n = 1). Treatment had to be postponed due to grade I thrombocytopenia in 2 patients. No bleeding episodes or obvious infectious complications occurred during treatment intervals. 1 patient experienced an allergic reaction to oxaliplatin which led to exclusion from further therapy. Arterial catheter dislocation occurred in 3 patients. In 10 patients evaluable for response we observed 3 partial responses, 2 minor responses, and 4 times stable disease. Only 1 patient had further progression of disease under treatment.

CONCLUSION

TACE, using a combination of mitomycin C, dexamethasone and interferon-alpha2b mixed with Spherex((R)), followed by oxaliplatin, FA and 5-FU, appears to be an effective and feasible treatment option in the case of liver metastasis of CRC refractory to standard systemic chemotherapy. This treatment is associated with tolerable toxicity, which becomes apparent mainly as asthenia, neurotoxicity or thrombocytopenia. These preliminary data warrant further evaluation for patients with refractory disease and would probably also be of interest for first-line treatment in this patient population.

Brackiella oedipodis gen. nov., sp. nov., gram-negative, oxidase-positive rods that cause endocarditis of cotton-topped tamarin (Saguinus oedipus)

A gram-negative, oxidase-positive, rod-shaped bacterium isolated from the heart of a cotton-topped tamarin was characterized by 16S rDNA sequence analysis, SDS-PAGE of whole-cell proteins, fatty acid analysis and biochemical tests. Outer-membrane proteins, iron-regulated outer-membrane proteins, lipopolysaccharides and siderophore production were studied. On the basis of the results, the organism belongs to the beta-Proteobacteria where it forms a separate line of descent, for which a novel genus and species are proposed, Brackiella oedipodis (LMG 19451T = DSM 13743T = NCIMB 13739T). Nearest phylogenetic neighbours of the new genus are Taylorella, Pelistega, Bordetella, Alcaligenes and Achromobacter.

Solubility equilibria in multicomponent oceanic salt systems from t = 0 to 200 °C. Model parameterization and databases

In this paper the application of Pitzer's equations for modeling of solubility equilibria in the hexary oceanic salt system Na+, K+, Mg2+, Ca2+ // Cl­, SO42­­H2 O and its subsystems over large temperature intervals is discussed. Lack of ternary solution data considerably restricts the use of the equations as an evaluation tool for the quality of solubility data. Models optimized for the available data in two temperature intervals have been derived. Since Pitzer's model gives no guidance for temperature dependence, the number of parameters is dominated by temperature coefficients. Thus, for extended temperature intervals other approaches like the Cohen-Adad formalism can be advantageous in solubility data evaluation.

HCG induced hyperthyreosis in germ cell cancer

Human germ cell tumors have the unique capacity for totipotential differentiation. AFP (the product of normal yolk sac) and HCG (produced by trophoblastic tissues) are frequently produced by germ cell tumors. The a-subunit of the glycoprotein HCG is identical to that of several pituitary glycoprotein hormones (e.g. TSH, LH, FSH), whereas the b-subunit of HCG, TSH, LH and FSH is homologous but distinct in the terminal amino acid sequence suggesting that HCG is part of a superfamily of gestational hormones. However, the role of TSH within this hormone superfamily is still not yet established. A 24-year old patient was admitted to our clinic because of a widespread recurrence of a germ cell tumor (stage IIIC, Lugano classification). The routine hematologic and blood chemical tests were normal, yet, an elevated HCG was found. In addition, increased levels of the thyroid hormones FT3 and FT4 were seen, although, this was not associated with clinical symptoms of a hyperthyreosis. There was no history of hyperthyreosis and thyroidal autoantibody screening revealed normal titers. An ultrasound examination of the thyroid gland showed no abnormalities and no iodine exposure had occurred during the last months. To mobilize peripheral stem cells (PBSC) he was initially treated with paclitaxel (175 mg/m2) and ifosfamide (8.000 mg/m2)) followed by apheresis of PBSC. The patient was then entered in our phase-II-study for relapsing germ cell carcinomas using a high-dose chemotherapy regime (paclitaxel 175 mg/m2, ifosfamide 9.000 mg/m2, carboplatin 900 mg/m2, etoposide 900 mg/m2) with subsequent retransfusion of collected stem cells. Due to cranial metastases an cranial irradiation was also performed. After three courses of this protocol an excellent partial remission of the tumor lesions was achieved and the HCG value dramatically decreased. Due to elevated thyroidal hormones, the patient was initially treated with thiamazole (20 mg) resulting in decrease of the thyroidal hormones. Thus, the thiamazole dose was reduced to 5 mg and then omitted. The decrease of the thyroidal hormones FT3 and FT4 strongly correlated with the reduction of HCG values (r2 0.91 and 0.77, p < 0.0008). To date there is only slight evidence that enhanced HCG levels may cause, at least in part, a hyperthyreosis (e.g. gestational hyperthyreosis), however, the underlying biochemical mechanism still remains unclear. In this case report we have demonstrated a clear positive correlation between HCG levels and thyroidal hormones in a patient with germ cell tumor suggesting a direct stimulation of hormone producing thyroidal cells by HCG, however, this was not associated with clinical symptoms of hyperthyreosis. Currently, several in vitro studies are underway in our laboratory to further elucidate the biochemical mechanisms of HCG induced hyperthyreosis.

Clonal diversity of Shiga toxin-producing Escherichia coli O157:H7/H- in Germany--a ten-year study

Two hundred and ten E. coli O157:H7/H- strains isolated from single cases and outbreaks of diarrhoea and haemolytic uraemic syndrome (HUS) in Germany between 1988 and 1998 were characterised by a range of molecular subtyping methods and phage typing in order to analyse their clonal nature. A high clonal heterogeneity, together with a considerable clonal stability, has been identified among the bacterial isolates and no single clonal type appeared to be geographically dominant. It is recommended to apply pulsed-field gel electrophoresis (PFGE) together with P gene profile determination (number and genomic positions of lambdoid bacteriophages) as laboratory tools for an extended epidemiological surveillance of E. coli OOFF phage typing will remain helpful as a first line of analysis, particularly in outbreak situations.

Schedule-dependent antagonism of gemcitabine and cisplatin in human anaplastic thyroid cancer cell lines

Anaplastic thyroid carcinoma (ATC) affects primarily elderly patients, with a median survival of 4-12 months after diagnosis. Presently, under clinical investigation the combination of cisplatin (CDDP) and gemcitabine (GEM) has promising activity in several of human tumor types. To develop new approaches for therapy of ATC, we evaluated the antineoplastic activity of GEM and CDDP alone (1-h and 24-h drug exposure) or in combination in the ATC cell lines SW1736, 8505C, C643, and HTh74. IC50 values were determined by the sulforhodamine B assay, activity was evaluated by the relative antitumor activity (RAA) and drug interaction assessed by isobologram analysis. GEM seemed to be active in ATC, with RAA ranging from 12-114 and CDDP only modestly active (RAA, 0.24-1.4). In four different drug schedules tested, the drug combination was additive when GEM preceded CDDP exposure (combination index, approximately 1), whereas when CDDP preceded GEM exposure the combination was significantly antagonistic (combination index, >1). In SW1736 and 8505C cells, we observed a strong S phase arrest and DNA synthesis inhibition 24 h after a 1-h exposure to an IC50 of CDDP. On the basis of molecular drug targets, cell cycle arrest points, and DNA synthesis inhibition, a model was developed to explain the interaction observed for the combination of GEM and CDDP. In conclusion, GEM shows promising cytostatic activity in ATC. Interaction of GEM and CDDP was schedule and dose dependent, favoring a regime in which GEM is followed by CDDP. Additionally, our model system suggests that DNA-synthesis inhibition and S phase arrest may be important determinants for the drug interaction between GEM and CDDP.

Cisplatin resistance and oncogenes--a review

Cisplatin is among the most widely used broadly active cytotoxic anticancer drugs; however, its clinical efficacy is often limited by primary or the development of secondary resistance. Several mechanisms have been implicated in cisplatin resistance, including reduced drug uptake, increased cellular thiol/folate levels and increased DNA repair. More recently, additional pathways have been characterized indicating that altered expression of oncogenes that subsequently limit the formation of cisplatin-DNA adducts and activate anti-apoptotic pathways may also contribute to the resistance phenotype. Several lines of evidence suggest that expression of ras oncogenes can confer resistance to cisplatin by reducing drug uptake and increasing DNA repair; however, this is not a uniform finding. Tumor cells, in contrast to normal cells, respond to cisplatin exposure with transient gene expression to protect or repair their chromosomes. The c-fos/AP-1 complex, a master switch for turning on other genes in response to DNA-damaging agents, has been shown to play a major role in cisplatin resistance. In addition, AP-2 transcription factors, modulated by protein kinase A, are also implicated in cisplatin resistance by regulating genes encoding for DNA polymerase beta and metallothionines. Furthermore, considerable evidence indicates that mutated p53 plays a significant role in the development of cisplatin resistance since several genes implicated in drug resistance and apoptosis (e.g. mismatch repair, bcl-2, high mobility group proteins, DNA polymerases alpha and beta, PCNA, and insulin-like growth factor) are known to be regulated by the p53 oncoprotein. Improved understanding of molecular factors for the development of cisplatin resistance may allow the prediction of clinical response to cisplatin-based treatment. Furthermore, the identification of oncogenes involved in cisplatin resistance has already led to in vitro approaches which successfully inactivated these genes using ribozymes or antisense oligodeoxynucleotides, thus restoring cisplatin sensitivity. It is conceivable that these strategies, once transferred to a clinical setting, may have the potential to enhance the efficacy of cisplatin against a great variety of malignancies and thus more fully exploit the antineoplastic and curative potential of this drug.

Clonal relationship of Salmonella enterica serovar typhimurium phage type DT104 in Germany and Austria

A new epidemic clone of Salmonella enterica serovar Typhimurium designated definitive phage type (DT) 104 has been emerging since 1990 to become most common type among S. Typhimurium isolates in Germany and Austria. Molecular fingerprinting (PFGE-pattern, plasmid profiles, IS200 pattern, ribotype, ERIC-type, OMP and MLE patterns) revealed the majority of the DT104 isolates to have clonal identity; they were designated as type 1 (about 95%). Moreover, clonal type 1 of DT104 was found to occur in sensitive as well as in a range of multiply drug-resistant variants and in a variety of plasmid profile types (in particular with small cryptic plasmids in the range of 1.0 to 5.0 Md). Since the clonal type 1 of DT104 has been identified among isolates from other countries, too, including such from the United Kingdom, the United Arab Emirates, the Philippines, and the Netherlands, its pandemic spread in man indicates that the import/export of this pathogen continues. About 5% of the DT104 isolates have been identified as genetically diverse indicating the independent appearance of the same multiple drug resistance and phage pattern phenotype among different Salmonella ancestor strains.

Preferential repair of the N-ras gene in K 562 cells after exposure to cisplatin

Cisplatin is one of the most active and widely used anticancer drugs; however, its clinical efficiacy is often limited by the development of resistance. Since several studies indicated that ras oncogenes may modulate the cellular response to cisplatin or radiation, we investigated the gene-specific repair of the N-ras gene in the human K 562 cell line after exposure to cisplatin using a novel nonradioactive polymerase chain reaction inhibition assay. This assay is based on the fact that DNA lesions can block the Taq polymerase and thereby result in a decreased amplification of a damaged segment compared to the amplification of the same segment in a non-damaged template. The overall genomic repair rate was measured by atomic absorption spectroscopy. Immediately after cisplatin exposure no amplification segment was observed. However, a complete restoration of the N-ras gene (2.4 kb) was seen after 8 h posttreatment incubation. In contrast, only 60% of the overall genome was repaired at this time. Our results clearly indicate that cisplatin-induced DNA lesions are more efficiently removed from transcribed regions within the DNA, suggesting that the efficiency of DNA repair in a given gene may be correlated to its transcriptional activity. Since ras oncogenes control several cellular signal transduction pathways, known to be involved in DNA damage response, preferential repair of the N-ras gene could therefore be an important step to prevent inactivation of cellular defense mechanisms after exposure to genotoxic agents.

Salmonella typhimurium IroN and FepA proteins mediate uptake of enterobactin but differ in their specificity for other siderophores

Salmonella typhimurium possesses two outer membrane receptor proteins, IroN and FepA, which have been implicated in the uptake of enterobactin. To determine whether both receptors have identical substrate specificities, fepA and iroN mutants and a double mutant were characterized. While both receptors transported enterobactin, the uptake of corynebactin and myxochelin C was selectively mediated by IroN and FepA, respectively.

The role of insulin-like growth factor I and its receptor in cell growth, transformation, apoptosis, and chemoresistance in solid tumors

Insulin-like growth factor I (IGF-I) exerts pleiotropic effects on mammalian cells via stimulation of its receptor (IGF-IR), a receptor tyrosine kinase. In vivo, IGF-I acts both as a local tissue growth factor and as a circulating hormone. In oncological research, IGF-I has received increased attention as the activated IGF-I/IGF-IR system displays mitogeneic, transforming, and anti-apoptotic properties in various cell types by stimulating distinct intracellular signaling pathways. Recent data suggest that the anti-apoptotic effect of IGF-I may mediate decreased sensitivity to chemotherapeutic drugs in vitro and in vivo. Thus, targeting the IGF-I/IGF-IR system could serve as an approach to overcome clinical drug resistance in certain tumors.

Ocular-adnexal lymphoid tumors: a clinicopathologic and molecular genetic study of 77 patients

PURPOSE

To determine whether molecular genetic analysis of ocular-adnexal lymphoid tumors, combined with histopathology and tumor location, is helpful in predicting which patients will develop systemic lymphoma.

METHODS

A combined retrospective and prospective study of 77 patients with ocular-adnexal lymphoid tumors was performed. The tumors were subdivided into conjunctival, orbital, and eyelid lesions, and all were studied using both routine histopathology and molecular genetic analysis.

RESULTS

Most lesions (70%) were small cell lymphomas of the mucosa-associated lymphoid tissue type, and the majority of tumors (90%) contained monoclonal or oligoclonal populations of lymphocytes discovered on molecular genetic analysis. Additionally, 72% of tumors exhibiting clonality had more than one gene rearrangement. Fifty-three percent of patients developed extraocular lymphoma sometime during the course of their disease. Patients with gene rearrangements on Southern blot hybridization had a 52% incidence of nonocular disease, compared with 63% of those without rearrangements. Patients with conjunctival tumors had a 37.5% incidence of nonocular disease, those with orbital tumors had a 54% incidence, and those with eyelid tumors had a 100% incidence of nonocular lymphoma. Only two patients died as result of systemic lymphoma.

CONCLUSIONS

Most ocular-adnexal lymphoid tumors are lymphomas of the mucosa-associated lymphoid tissue type. The majority of tumors exhibit gene rearrangements on molecular genetic analysis, and this technique was not helpful in predicting which patients would develop nonocular lymphoma. Tumor location did have predictive value: Conjunctival lesions had the lowest incidence of nonocular lymphoma, and lid lesions had the highest incidence. Even with disseminated disease, most patients have a favorable prognosis with treatment.

Topoisomerase-I inhibitor SN-38 can induce DNA damage and chromosomal aberrations independent from DNA synthesis

BACKGROUND

SN-38 is the active metabolite of the topoisomerase-I (topo-I) inhibitor Irinotecan (CPT-11). Generally, topo-I inhibitors stabilize the complex between topo-I and DNA which collide with moving DNA replication forks, eventually leading to double stranded DNA damage. Therefore, topo-I inhibitors are regarded as S-phase specific. The present study investigated S-phase dependent and independent effects of SN-38.

MATERIALS AND METHODS

Effects of exposure of A2780 cells to SN-38 (2 hours) were studied by assessing DNA/protein crosslinks, DNA damage and cytogenetic aberrations.

RESULTS

A close correlation (r2 = 0.97) was established between drug-induced DNA/protein crosslinks and double stranded DNA breaks. Cytogenetic analysis revealed near maximum clastogenic effects already evident immediately following 2 hours drug exposure. However, qualitatively, chromatid breaks at 24 hours were different from those at 0 hours, in that at 24 hours they were associated with radial chromosome configurations and sister chromatid exchanges.

CONCLUSION

The data corroborate that the S-phase dependent mechanism of action of topo-I inhibitors is also applicable to SN-38. The cytogenetic data indicate two distinct interactions of SN-38 with DNA: immediate induction of chromatid breaks independent from DNA synthesis, and induction of chromatid breaks associated with radial chromosome configurations dependent on DNA synthesis.

Cellular determinants of resistance to indolocarbazole analogue 6-N-formylamino-12,13-dihydro-1,11-dihydroxy-13(beta-D-glucopyranosyl)- 5H-indolo[2,3-alpha]pyrrolo[3,4-c]carbazole-5,7(6H)-dione (NB-506), a novel potent topoisomerase I inhibitor, in multidrug-resistant human tumor cells

Membrane protein-associated alterations in cellular drug accumulation have been recently implicated in resistance to topoisomerase I (TOP-I)-interactive drugs. The present study investigated the cellular determinants of resistance to the indolocarbazole compound NB-506 [6-N-formylamino-12,13-dihydro-1,11-dihydroxy-13(beta-D-glucopyranosyl)- 5H-indolo[2,3-alpha]pyrrolo[3,4-c]carbazole-5,7(6H)-dione], a structurally novel TOP-I-interactive drug, in parental and multidrug-resistant tumor cells expressing either the P-170 glycoprotein (Pgp170) or multidrug resistance protein (MRP). MRP-expressing 250-fold doxorubicin-resistant human fibrosarcoma HT1080/DR4 tumor cells were drug sensitive to NB-506 and camptothecin (CPT) (resistance factor: 0.7 and 0.8, respectively) with no alterations of TOP-I parameters including DNA relaxation, expression of TOP-I protein and mRNA. In contrast, doxorubicin-resistant human ovarian A2780/Dx5 tumor cells [pgp170 phenotype] were 6.2-fold resistant to NB-506, whereas resistance to CPT was 2.6-fold. HPLC analysis of cellular NB-506 accumulation showed no significant differences between A2780 and A2780/Dx5 cells (peak intracellular concentrations after 120-min exposure to 10 microM NB-506: 400+/-85.0 and 352+/-95.1 nmol NB-506/mg protein, respectively). However, resistant A2780/Dx5 cells expressed a lower amount of TOP-I mRNA and 29% protein levels of TOP-I compared to parental A2780 cells, resulting in decreased TOP-I catalytic activity (3.17+/-0.02 vs. 1.16+/-0.15 rel.U/microg nuclear protein) and reduced induction of NB-506-mediated cleavable complex formation in A2780/Dx5 cells. Furthermore, the lower induction of NB-506-induced protein-linked DNA breaks (PLDB) in A2780/Dx5 cells correlated with significantly decreased DNA 12.2-440 kb size fragmentation in these cells. The present study demonstrates that expression of MRP and Pgp170 does not confer resistance to NB-506. Resistance to indolocarbazole substance NB-506 in A2780/Dx5 cells was only related to downregulation of TOP-I associated with lower induction of cleavable complex formation and DNA fragmentation. The data reported herein may indicate that the new indolocarbazole compound NB-506 has potent antitumor efficacy in membrane-associated multidrug resistance.

Novel cellular determinants for reversal of multidrug resistance in cells expressing P170-glycoprotein

The newly synthesized calcium channel blocker, Ro44-5912, significantly potentiates doxorubicin (Dox)-induced cytotoxicity at non-cytotoxic concentrations in Dox-resistant human ovarian cell line, A2780/DX5, overexpressing P170-glycoprotein (Pgp). Induction of DNA single- and double-strand breaks (ssbs and dsbs) was measured using alkaline elution and constant-field gel electrophoresis (CFGE) assays. The results indicate that potentiation of the cytotoxicity of Dox by Ro44-5912 was accompanied by significant increases in both, Dox-induced DNA ssbs and dsbs in the resistant cells. Pulsed-field gel electrophoresis (PFGE) analysis showed that Dox induced DNA fragments in the 50-800 kilobase (kb) and 0.8-5.7 megabase (Mb) ranges. The majority of the newly synthesized DNA fragments were in the 50-800 kb range. Ro44-5912 treatment resulted in significant potentiation of DNA fragmentation in the 50-800 kb range with a minor increase in 0.8-5.7 Mb DNA fragments, suggesting that the modulator functions by potentiating nascent DNA fragmentation in the resistant cells. Exposure to Dox with Ro44-5912 was associated with a prolonged blockage of cells in the S-phase. In contrast, exposure to Dox alone resulted in temporary blockage of cells in G2/M phase (approximately 24 h) followed by restoration of cell proliferation and normal DNA histograms at 48 h after 2 h drug exposure. Incorporation of BrdUrd by flow cytometric analysis was inhibited by Dox in the presence of Ro44-5912, showing that there is a block of DNA replication. An increased damage in newly synthesized DNA could concur with a blocked DNA replication. Moreover, slowing progression through the S-phase in cells exposed to Dox in combination with Ro44-5912 is accompanied by increased sensitivity of Dox poisons, indicating a correlation of specific S-phase perturbation with the reversal of Dox resistance by Ro44-5912 in cells expressing Pgp. The results suggest that drug-induced augmentation of nascent DNA fragmentation and specific cell-cycle perturbation are potentially important molecular determinants for reversal of multidrug resistance in addition to restoration of intracellular drug retention.