Downregulation of cystine transporter xc by irinotecan in human head and neck cancer FaDu xenografts.

BACKGROUND: The purpose of this study was: (1) to document the critical requirement of cystine for growth of human tumor cells in vitro, and (2) to determine the effect of the anticancer agent irinotecan on the cystine transporter x(c)(-) in head and neck FaDu xenografts. METHODS: Cell growth was measured by sulforhodamine B assay. xCT protein, glutathione (GSH) and DNA damage were determined using Western blot, spectrophotometry, and immunohistochemistry, respectively. RESULTS: Depletion of cystine from the medium inhibited tumor cell growth. Treatment of FaDu tumor with a therapeutic dose of irinotecan resulted in depression of xCT protein levels, leading to tumor growth retardation and downregulation of GSH with increased reactive oxygen species (ROS). The accumulation of ROS correlated with increased DNA damage as evidenced by increased H2AX. CONCLUSION: Depression of xCT protein by irinotecan resulted in downregulation of GSH and increase in ROS, which could be the other possible mechanisms of DNA damage by irinotecan.

Hypoxia-specific drug tirapazamine does not abrogate hypoxic tumor cells in combination therapy with irinotecan and methylselenocysteine in well-differentiated human head and neck squamous cell carcinoma a253 xenografts.

Well-differentiated hypoxic regions in head and neck squamous cell carcinoma like in A253 xenografts are avascular and, therefore, hinder drug delivery leading to drug resistance and tumor regrowth. Methylselenocysteine (MSC, 0.2 mg/mouse per day per oral for 35 days starting 7 days before the first irinotecan (CPT-11)) has been found to increase efficacy of a wide variety of chemotherapeutic agents including CPT-11 (100 mg/kg per week x 4 intravenously). Whereas CPT-11 leads to a 10% complete response (CR) in A253 xenografts, the combination of MSC and CPT-11 increased the CR to 70%. Surviving tumors were found to consist largely of avascular hypoxic regions. Here, we investigated the combination of tirapazamine (TPZ, 70 mg/kg per week intraperitoneal x 4 administered 3 or 72 hours before CPT-11), a bioreductive drug in clinical trial with selective toxicity for hypoxic cells, with MSC and CPT-11 in further enhancing the cure rates. Tumor response, change in tumor hypoxic regions, and DNA damage were monitored in vivo. Tirapazamine administered 3 hours before CPT-11 in combination with MSC + CPT-11 led to a lower tumor burden. Tirapazamine did not increase cure rate beyond that of MSC + CPT-11 combination and was instead found to decrease cures with no evidence of an increased DNA damage or a significant reduction in avascular hypoxic tumor regions. CD31 immunostaining in A253 demonstrated disruption of tumor vessels by TPZ that could lower cytotoxic drug delivery to carbonic anhydrase IX-positive hypoxic tumor cells and may explain at least partially these unexpected results.

Potential tumor markers for human gastric cancer: an elevation of glycan:sulfotransferases and a concomitant loss of alpha1,2-fucosyltransferase activities.

PURPOSE: Several reports indicate a complexity in glycosyltransferase activities which lead to several tumor associated carbohydrate structures in gastric carcinoma. The present study was aimed to identify the carbohydrate associated transferases which exhibit the most marked and consistent change of activity in gastric tumorigenesis. METHODS: We examined the levels of fucosyl, beta-galactosyl-, beta-N-acetylgalactosaminyl, sialyl- and glycan:sulfotransferase activities, which generate the outer ends of oligosaccharide chains in tumorous and adjacent normal gastric tissues of the same patient in ten gastric carcinoma cases by using well defined specific synthetic acceptors utilized in our several earlier published studies as referenced in the text (e.g. Chandrasekaran et al. in J Biol Chem 279:10032-10041, 2004; Biochemistry 44:15619-15635, 2005; Carbohydr Res 341:983-994, 2006). RESULTS: Among glycosyltransferases only alpha1,2-fucosyltransferase (FT) was unique in showing a remarkable 40-90% decrease of activity in seven cases. Uniquely several fold elevation of Gal3Sulfo-T(2) (1.9 --> 156.7 fold) and Gal3Sulfo-T(4) (2.4 --> 149.0 fold) activities in all ten cases and moderate elevation of GlcNAc6Sulfo-T (1.3 --> 37.5 fold) activities in nine cases were identified. Poorly differentiated Signet ring cell carcinoma expresses mainly Gal3Sulfo-T(2) activity whereas poorly differentiated adenocarcinoma express predominantly Gal3Sulfo-T(4) activity and also GlcNAc6Sulfo-T activity. But, very low level of these sulfotransferase activities were identified in moderately differentiated gastric carcinomas as well as non-epithelial gastric stromal sarcoma. CONCLUSION: Up regulation of glycan:sulfotransferase activities and down regulation of alpha1,2-fucosyltransferase activity are apparently associated with human gastric tumorigenesis.

The mechanism of methylselenocysteine and docetaxel synergistic activity in prostate cancer cells.

The study was designed to evaluate the combination treatment of methylselenocysteine (MSeC) and docetaxel and to delineate the underlying mechanism associated with observed in vitro synergy between MSeC and docetaxel in prostate cancer cells. Cells were treated with different concentrations and schedules (concurrent or sequential) of MSeC and docetaxel alone or in combination. Cell growth/death was assessed with sulforhodamine B assay, trypan blue assay, and time-lapse video. Loewe synergism/antagonism model was used to determine whether the combination effect was additive, synergistic, or antagonistic. Apoptosis and caspase-3 activity were evaluated with cell death ELISA assay and caspase activity assay, respectively. Synergy between MSeC and docetaxel was further assessed in the presence and absence of z-VAD-fmk, a pan-caspase inhibitor. Effect of MSeC and docetaxel alone or in combination on the cellular expression of the antiapoptotic protein survivin was measured with Western blot analyses. Pretreatment with MSeC was crucial to enhance docetaxel antitumor activity. The enhanced antitumor activity of the sequential combination treatment of MSeC and docetaxel (MSeC/docetaxel) was highly synergistic. Apoptosis increased after MSeC/docetaxel, compared with each drug alone or concurrent treatment. Pretreatment with z-VAD-fmk converted the synergy into antagonism, suggesting that the synergy is caspase-dependent apoptosis. The survivin level was down-regulated following MSeC/docetaxel treatment when compared with each drug alone. In conclusion, pretreatment with MSeC was essential to markedly sensitize cells to docetaxel. The synergy between MSeC and docetaxel in C2G prostate cancer cells is associated with increased level of caspase-dependent apoptosis and decreased level of survivin.

Effect of amphotericin B and micafungin combination on survival, histopathology, and fungal burden in experimental aspergillosis in the p47phox-/- mouse model of chronic granulomatous disease.

Chronic granulomatous disease (CGD) is an inherited disorder of the NADPH oxidase characterized by recurrent life-threatening bacterial and fungal infections. We characterized the effects of single and combination antifungal therapy on survival, histopathology, and laboratory markers of fungal burden in experimental aspergillosis in the p47phox-/- knockout mouse model of CGD. CGD mice were highly susceptible to intratracheal Aspergillus fumigatus challenge, whereas wild-type mice were resistant. CGD mice were challenged intratracheally with a lethal inoculum (1.25 x 10(4) CFU/mouse) of A. fumigatus and received one of the following regimens daily from day 0 to 4 after challenge (n = 19 to 20 per treatment group): (i) vehicle, (ii) amphotericin B (intraperitoneal; 1 mg/kg of body weight), (iii) micafungin (intravenous; 10 mg/kg), or (iv) amphotericin B plus micafungin. The rank order of therapeutic efficacy based on prolonged survival, from highest to lowest, was as follows: amphotericin B plus micafungin, amphotericin B alone, micafungin alone, and the vehicle. Lung histology showed pyogranulomatous lesions and invasive hyphae, but without hyphal angioinvasion or coagulative necrosis. Treatment with micafungin alone or combined with amphotericin B produced swelling of invasive hyphae that was not present in mice treated with the vehicle or amphotericin B alone. Assessment of lung fungal burden by quantitative PCR showed no significant difference between treatment groups. Serum galactomannan levels were at background despite documentation of invasive aspergillosis by histology. Our findings showed the superior efficacy of the amphotericin B and micafungin combination compared to either agent alone after A. fumigatus challenge and also demonstrated unique features of CGD mice as a model for experimental aspergillosis.

Differential expression of survivin-2B and survivin-DeltaEx3 is inversely associated with disease relapse and patient survival in non-small-cell lung cancer (NSCLC).

Although it was observed that inhibition of the antiapoptotic protein survivin expression in lung cancer cells induces apoptosis, the expression and role of survivin variants (survivin-2B and survivin-DeltaEx3) in lung cancer have not yet been characterized. We analyzed 24 non-small-cell lung cancer (NSCLC) samples by semi-quantitative RT-PCR. Surprisingly, our results revealed that high-level expression of survivin-2B is significantly associated with the patient category of "no relapse and alive" (p-value<0.0001). In contrast, high-level expression of survivin-DeltaEx3 is highly associated with the patient category of "relapse and dead" (p-value<0.0001). Consistent with this observation, exogenous expression of survivin-2B in A549 lung cancer cells inhibited cell growth, disrupted the mitochondria potential, and induced apoptotic cell death, while expression of survivin-DeltaEx3 protected the mitochondria potential and facilitated cell survival. These findings provide evidence that survivin-2B and survivin-DeltaEx3 play opposite roles in disease relapse and NSCLC cell survival, which is likely through the differential modulation of mitochondrial potential. Thus, controlling the differential expression of survivin-2B and survivin-DeltaEx3 may represent novel approaches for cancer therapeutics in NSCLC.

Image analysis using the fluorochromasia assay to quantify tumor drug sensitivity.

A method of assessing chemosensitivity of tissue utilizing tissue fluorescence and image analysis was implemented to provide a rapid and quantitative means of assessing the effect of drugs on tissue metabolic activity and proliferative capacity. The fluorescent microscopic image captured by a silicon-intensified target (low-light-detecting) camera and linked to an image- processing unit was measured for fluorescent brightness and tumor image area. An established rodent model served to characterize the system's ability to measure serially the tumor's metabolic activity and growth. Further studies on fresh human tumors were conducted with a novel topoisomerase II inhibitor, NC-190. Tumor image area and fluorescent brightness were measured 24 h pretreatment, 48 h posttreatment, and 48 h post-drug removal. Fifty-five percent (28/51) of fresh human tumors showed sensitivity to 48-h exposure to 10, 30, or 100 microM NC-190. The potential benefit of this technique is the ability to predict the response of tumors to chemotherapeutic agents as a laboratory tool for preclinical drug evaluation and clinically prior to the commencement of therapy.

Lack of microvessels in well-differentiated regions of human head and neck squamous cell carcinoma A253 associated with functional magnetic resonance imaging detectable hypoxia, limited drug delivery, and resistance to irinotecan therapy.

PURPOSE: Combination chemotherapy with irinotecan (CPT-11; 50 mg/kg/week x 4 intravenously), followed 24 hour later by 5-fluorouracil (50 mg/kg/week x 4 intravenously), results in 10 and 100% cure rates of animals bearing human head and neck squamous cell carcinoma xenografts A253 and FaDu, respectively. A253 consists of 30% well-differentiated and avascular and 70% poorly differentiated regions with low microvessel density (10/x400), whereas FaDu is uniformly poorly differentiated with higher microvessel density (19/x400). Studies were carried out for determining the role of well-differentiated and avascular regions in drug resistance in A253 and detection of such regions with noninvasive functional magnetic resonance (fMR) imaging. EXPERIMENTAL DESIGN: Tumors were harvested for histopathologic evaluation and immunohistochemistry (CD31, CD34; differentiation marker: involucrin; hypoxia markers: carbonic anhydrase IX, pimonidazole; vascular endothelial factor (VEGF) and Ki67) immediately after fMR imaging following the 3rd dose of chemotherapy. High-performance liquid chromatography determination of intratumoral drug concentration of 7-ethyl-10-hydroxyl-camptothecin and autoradiography with (14)C-labeled CPT-11 was done 2 hours after CPT-11 administration. RESULTS: Although A253 xenografts showed three times higher concentration of 7-ethyl-10-hydroxyl-camptothecin, FaDu was more responsive to therapy. After therapy, A253 tumor consisted mostly (approximately 80%) of well-differentiated regions (positive for involucrin) lacking microvessels with a hypoxic rim (positive for carbonic anhydrase IX and pimonidazole) containing few proliferating (Ki67 positive) poorly differentiated cells. Autoradiography revealed that well-differentiated A253 tumor regions showed 5-fold lower (14)C-labeled CPT-11 concentrations compared with poorly differentiated areas (P < 0.001). Blood oxygen level dependant fMR imaging was able to noninvasively distinguish the hypoxic and well-vascularized regions within the tumors. CONCLUSION: Avascular-differentiated regions in squamous cell carcinoma offer sanctuary to some hypoxic but viable tumor cells (carbonic anhydrase IX and Ki67 positive) that escape therapy because of limited drug delivery. This study provides direct evidence that because of a specific histologic structure, avascular, well-differentiated hypoxic regions in tumors exhibit low drug uptake and represent a unique form of drug resistance.

Upregulation of the tissue inhibitor of metalloproteinase-1 protein is associated with progression of human non-small-cell lung cancer.

PURPOSE: Tissue inhibitors of metalloproteinases (TIMPs) are naturally occurring inhibitors of matrix metalloproteinases (MMPs). It has been shown that TIMP-1 may be a multifunctional protein. Little is known about the role of TIMP-1 in progression and metastasis of human lung cancer (tumor inhibiting or tumor promoting), although studies using a variety of techniques have analyzed the expression of TIMP-1 mRNA and/or protein in human cancers. PATIENTS AND METHODS: We examined the expression of TIMP-1 protein by immunohistochemistry in patients (n = 160) with primary respectable (stage I to IIIA) non-small-cell lung cancer (NSCLC). RESULTS: Twenty-seven percent of the tumors (43 of 160) demonstrated elevated expression of this protein. We demonstrate that overexpression of TIMP-1 protein is associated with an adverse outcome. In addition, disease stage, patient's age, and performance status were all significantly related to survival. In multivariate analyses, patients with high TIMP-1 expression had a 90% increased risk of death when compared with those with low expression (relative risk, 1.92; 95% CI, 1.19 to 3.09; P =.008). TIMP-1 expression did not correlate with expression of MMP-2 and MMP-9. CONCLUSION: These results suggest that TIMP-1, independent of its inhibiting activity of MMPs, may have other function(s) critical for NSCLCs. The significance of our results is two-fold. The adverse outcome in patients with overexpression of TIMP-1 indicates its potential prognostic value in NSCLC. Thus, TIMP-1 overexpression may serve to help identify patients with particularly aggressive disease for adjuvant treatments. In addition, the TIMP-1 molecule may represent a novel therapeutic target for treatment of some NSCLCs.

Definition of a region of loss of heterozygosity at chromosome 11q23.3-25 in head and neck squamous cell carcinoma using laser capture microdissection technique.

To date, loss of heterozygosity (LOH) studies on HNSCC have had limited success in identifying a confined region of loss on chromosome 11q partially due to the heterogeneous nature of tumor tissue examined. Additionally, little is known about the role of the 11q allelic deletion in HNSCC tumorigenesis and current reports are conflicting. The aim of this study was to better define LOH at distal 11q by using combination of a pure cell population procured by laser capture microdissection (LCM) and subsequent sensitive PCR amplification of polymorphic microsatellites. This study analyzed HNSCC for LOH using a panel of 5 microsatellite markers spanning 11q23-25. Thirty-four paired DNA samples from tumor and autologous normal tissue were harvested by LCM technique to ensure a pure cell population for PCR amplification. Approximately 2000 to 3000 cells were procured from each sample. Twenty-one of 34 cases (62%, P < 0.001) showed LOH on at least one of the loci examined. The highest frequency of LOH was found at the 11q23.3-25 segment, with 44% at marker D11S968 and 35% at marker D11S1316. A distinct novel region of frequent LOH at 11q23.3-25, defined by D11S1316 and D11S968, was identified. No allelic loss was found in any normal squamous tissue samples. To study LOH in HNSCC, combination of pure cell population procurement by LCM and sensitive PCR provides a more accurate approach than the conventional method using a bulk of heterogeneous tissue. A novel region of LOH at 11q23.3-25 was defined. LOH in this region may harbor putative tumor suppressor gene(s) critical for HNSCC. Furthermore, these allelic losses were not found in any non-neoplastic squamous tissue samples, clarifying prior discrepant data.

Therapeutic synergy between irinotecan and 5-fluorouracil against human tumor xenografts.

PURPOSE: Although the combination of irinotecan and 5-Fluorouracil is clinically active, it is associated with significant toxicity and resistance. Studies were carried out to define the optimal dosage, sequence, and timing for the combination in mice bearing xenografted human tumors. EXPERIMENTAL DESIGN: The maximum tolerated dose of irinotecan and 5-Fluorouracil in combination was determined in nude mice. Therapeutic efficacy against established human colon carcinoma xenografts, HCT-8 and HT-29, and human head and neck squamous cell carcinoma xenografts, FaDu and A253, was determined using the rugs individually, simultaneously, and in sequence with various intervals in between. Treatments were i.v. weekly x 4. Immunohistochemical and reverse transcription-PCR measurements of relevant drug-metabolizing enzymes, apoptosis-related proteins, cell cycle distribution, cyclin A, and S phase fraction expression were carried out and compared with the therapeutic outcome. RESULTS: The maximum tolerated dose of irinotecan resulted in cure rates of 30% or less in all xenografts. No cures were achieved with FUra alone. Concurrent administration of irinotecan and FUra, or of FUra 24 h before irinotecan, resulted in cure rates of <20%, except for FaDu (60%). Administration of irinotecan 24 h before FUra resulted in the highest cure rates, 80% in HCT-8, 0% in HT-29, 100% in FaDu, and 10% in A253. CONCLUSIONS: The optimal therapeutic synergy was achieved when irinotecan was administered 24 h before 5-Flurouracil. Sensitivity to this combination was associated with poor differentiation status, higher cyclin A index, recruitment of cells into S phase, and induction of Bax expression and apoptosis.

Altered E-cadherin and epidermal growth factor receptor expressions are associated with patient survival in lung cancer: a study utilizing high-density tissue microarray and immunohistochemistry.

E-cadherin (E-cad) and epidermal growth factor receptor (EGFR) are important cell adhesion and signaling pathway mediators. This study aimed to assess their expression in lung adenocarcinoma (AdC) and squamous cell carcinoma (SCC) and their association with clinicopathologic variables. In all, 130 resectable lung cancers (stages I-IIIA) were studied using a high-density tissue microarray. Two to three cores from each case were arrayed into three blocks using a Beecher system. Immunohistochemistry was performed using an avidin-biotin complex method and monoclonal antibodies against E-cad and EGFR. Unequivocal membrane staining in >10% of tumor cells was considered as a positive expression of E-cad and EGFR. Markers expression and coexpression were analyzed against clinicopathologic variables (age, gender, smoking status, performance status, weight loss, histology, grade, stage, and lymph node involvement) and patient survival. There were 118, 126, and 115 cases that were fully assessable for E-cad, EGFR, and both markers, respectively. For E-cad, 65 cases (55%) were positive (+), 53 (45%) were negative (-); 23 cases of the negative group had only cytoplasmic staining. For EGRF, 43 cases (34%) were (+), and 83 (66%) were (-). There was no significant association between E-cad or EGFR, and any of the clinicopathologic variables except for an association between EGFR(+) and SCC histologic type. Both negative and cytoplasmic staining of E-cad correlated with shorter patient survival with P=0.008 and 0.002, respectively. EGFR expression did not correlate with patient survival; however, patients with E-cad(-)/EGFR(+) phenotype had poorer survival than those with E-cad(+)/EGFR(-) (P=0.026). Our study suggests that lung AdC and SCC may be stratified based on expression of E-cad and EGFR with the E-cad(-)/EGFR(+) expression having a worse disease outcome. Moreover, the cytoplasmic expression of E-cad may represent an altered localization of this protein in association with tumorigenicity.

HER-2/neu protein expression and gene alteration in stage I-IIIA non-small-cell lung cancer: a study of 140 cases using a combination of high throughput tissue microarray, immunohistochemistry, and fluorescent in situ hybridization.

Regarding HER-2/neu expression (gene or protein level) in lung cancer, several studies with inconsistent results have been recently reported, partially due to variable techniques used and/or heterogeneous populations examined. The objective of this study was to examine HER-2/neu expression in a well-defined cohort of non-small-cell lung cancers (NSCLC) and in nonneoplastic lung tissue utilizing a combination of high-density tissue microarray, immunohistochemistry (IHC), and fluorescent in situ hybridization (FISH) under uniform test conditions. One hundred forty stage I-IIIA primary NSCLCs and 38 non-neoplastic lung samples were examined. IHC, using an FDA-approved Hercept monoclonal antibody kit, was performed and HER-2/neu gene alteration was assessed by FISH. The association of expression of HER-2/neu with clinicopathologic parameters was analyzed. Ninety-four percent of tumor samples (131/140) were fully interpretable after tissue processing. Twenty-five of them (19%) overexpressed (2+, 3+) HER-2/neu, while 106 (81%) had no or weak expression. All thirty-four interpretable non-neoplastic lung samples were negative for HER-2/neu alteration at protein and gene level. HER-2/neu protein overexpression correlated well with HER-2/neu gene amplification (r =.83, P < 0.001). HER-2/neu overexpression was significantly associated with histologic subtype: 19 adenocarcinomas (19/82, 23%) versus 4 squamous cell carcinomas (4/44, 9%) overexpressed Her-2/neu (P = 0.04). Statistical significance was observed between HER-2/neu expression and tumor differentiation, with strong positive (3+) expression observed more frequently in poorly differentiated tumors (P = 0.01). Patients with HER-2/neu abnormalities, particularly HER-2/neu gene amplification, exhibited a shorter survival (P = 0.043). The statistically significant difference (P < 0.005) between HER-2/neu alteration in tumor samples(25/131, 19%) and in the nonneoplastic tissue (0/34, 0%) implies that HER-2/neu may have a role in the carcinogenesis of NSCLC. The findings provide evidence supporting the hypothesis that the HER-2/neu receptor may represent a useful molecular target in the treatment of NSCLC. The significant association of HER-2/neu expression and gene amplification with poorly differentiated carcinoma compared with well differentiated carcinoma suggests that HER-2/neu may be involved in NSCLC tumor evolution. Patients with HER-2/neu gene amplification and strong positive expression of HER-2/neu protein showed a strong tendency toward shorter survival.

A new nonlinear mixture response surface paradigm for the study of synergism: a three drug example.

A flexible approach to response surface modeling for the study of the joint action of three active anticancer agents is used to model a complex pattern of synergism, additivity and antagonism in an in vitro cell growth assay. The method for determining a useful nonlinear response surface model depends upon a series of steps using appropriate scaling of drug concentrations and effects, raw data modeling, and hierarchical parameter modeling. The method is applied to a very large in vitro study of the combined effect of Trimetrexate (TMQ), LY309887 (LY), and Tomudex (TDX) on inhibition of cancer cell growth. The base model employed for modeling dose-response effect is the four parameter Hill equation [1]. In the hierarchical aspect of the final model, the base Hill model is treated as a function of the total amount of the three drug mixture and the Hill parameters, background B, dose for 50% effect D50, and slope m, are understood as functions of the three drug fractions. The parameters are modeled using the canonical mixture polynomials from the mixture experiment methodologies introduced by Scheff [2]. We label the model generated a Nonlinear Mixture Amount model with control observations, or zero amounts, an "NLMAZ" model. This modeling paradigm provides for the first time an effective statistical approach to modeling complex patterns of local synergism, additivity, and antagonism in the same data set, the possibility of including additional experimental components beyond those in the mixture, and the capability of modeling three or more drugs.

Thymidine and hypoxanthine protection patterns of the folic acid-enhanced synergies for combinations of trimetrexate plus a polyglutamylatable inhibitor of purine or thymidylate synthesis against human ileocecal HCT-8 cells.

In order to examine the intracellular locus of the folic acid (PteGlu)-enhanced synergies of trimetrexate (TMQ) plus the thymidylate synthase (TS) inhibitor, raltitrexed (RTX), and TMQ plus the glycinamide ribonucleotide formyltransferase (GARFT) inhibitor, AG2034, comprehensive protection studies with thymidine (dThd) and hypoxanthine (HX) were conducted in a 96-well plate cell growth inhibition (sulforhodamine B) assay. Current modeling techniques were extended to characterize these protection patterns involving multiple-agent interaction. Wild-type human ileocecal HCT-8 cells and DW2, a subline deficient in folylpoly-gamma-glutamate synthetase (FPGS) were individually treated for 96 h with TMQ, AG2034 and a 1:1 mixture of TMQ:AG2034 or with TMQ, RTX, and a 1:1 mixture of TMQ:RTX in the presence of PteGlu (2.3 or 40 micro M) and the protection agents (10 micro M dThd and/or 100 micro M HX). Drug treatments were randomly assigned to wells. Both isobols and 3-dimensional concentration-effect surfaces were used to assess the nature and the intensity of drug interactions. The structural Hill model was fitted to data with weighted non-linear regression for most cases. A so-called 'double Hill' model was sometimes more appropriate when a plateau in the middle of the concentration-effect curve was found. In HCT-8 and DW2 cells at 2.3 and 40 micro M PteGlu, inhibition of DHFR by TMQ induced antithymidylate and antipurine effects; AG2034 and RTX selectively inhibited de novo purine or thymidine synthesis, respectively. dThd protection increased the PteGlu-enhancement of the TMQ + AG2034 synergy, whereas HX protection increased the PteGlu-enhancement of the TMQ + RTX synergy. The PteGlu-enhanced synergies of TMQ + AG2034 and TMQ + RTX occur primarily through inhibition of purine synthesis and inhibition of thymidylate synthesis, respectively. These results further substantiate the hypothesis that the nonpolyglutamylatable DHFR inhibitor, TMQ, acts as a modulator by decreasing the protection by PteGlu of cells against the polyglutamylatable AG2034 and RTX.

Thyroid transcription factor-1 expression prevalence and its clinical implications in non-small cell lung cancer: a high-throughput tissue microarray and immunohistochemistry study.

Thyroid transcription factor 1 (TTF-1), a homeodomain-containing transcription factor, plays a pivotal role in lung development, cell growth, and differentiation processes. The current literature reports considerable variation in frequency of TTF-1 protein expression in human non-small cell lung cancer (NSCLC). TTF-1 expression has not been extensively investigated as a prognostic marker in NSCLC. To assess the prevalence of TTF-1 expression, and to evaluate its potential role in disease prognosis, 140 stage I-IIIA NSCLCs with long-term follow-up were studied under uniform conditions using high-density tissue microarray (TMA) combined with immunohistochemistry. Patient survival and association of TTF-1 expression with clinicopathologic parameters were analyzed. One hundred twenty-six tumor samples were fully assessable after tissue processing. Sixty-four samples (50.8%) expressed TTF-1 and 62 (49.2%) displayed no expression. TTF-1 expression was significantly (P < 0.001) correlated with histological subtype: 51 adenocarcinomas (AdCs) (51 of 75; 68%) versus 9 squamous cell carcinomas (SCCs) (9 of 43; 21%) were TTF-1 positive. TTF-1 expression, performance status, nodal status, and tumor stage were significantly related to patient survival. In multivariate analysis, positive TTF-1 expression tended to favor a better patient outcome (P = 0.05). Overall, NSCLC patients with positive TTF-1 expression had a median survival of greater than 57.3 months, whereas those with negative expression had a median survival of 39.4 +/- 5.2 months (log-rank test, P = 0.0067). In this study we found that TTF-1 is predominately expressed in adenocarcinoma. The loss of TTF-1 expression was associated with aggressive behavior of NSCLCs. The results from this study strongly indicate that further investigation is warranted to better define the role of TTF-1 as a prognostic factor in this malignancy.

Loss of cables protein expression in human non-small cell lung cancer: a tissue microarray study.

Loss of heterozygosity (LOH) on chromosome 18q is common in lung cancer. The genes involved in LOH on 18q in lung cancer have not been well characterized. Cables, a cyclin-dependent kinase (cdk) interacting protein, has recently been identified and mapped to human chromosome 18q11-12. Cables inhibits cell growth and suppresses tumor formation in nude mice, making it a candidate gene for 18q LOH in lung cancer. Little is known regarding Cables protein expression in human non-small cell lung cancer (NSCLC). In this study we examined Cables expression in 163 NSCLC and nonneoplastic lung specimens using tissue microarrays. Strong nuclear staining was present in normal lung and bronchial tissue. We also evaluated the Cables protein expression pattern and its correlation with histopathologic features and with clinical course of NSCLC. The results of the present study demonstrate for the first time that numerous NSCLCs (45%) lose Cables expression. Furthermore, more adenocarcinomas show a loss of this novel protein than do squamous counterparts. The relationship between tumor histology type and Cables expression appears to be statistically significant (P = 0.028). Our results suggest that Cables may be involved in the pathogenesis of NSCLC.

Tumor antigens and markers for breast and ovarian cancers.

Use of vaccines to prevent and treat breast and ovarian cancer is a highly attractive approach because of the expected minimal side effects and the potential to predict individuals likely to benefit from vaccination. To fully harness the capacity of the immune system for this purpose, it is necessary to characterize tumor antigens for these cancers so that purified antigens can be tested for their immunogenicity in individual patients and for their suitability as targets of vaccine-induced immunity. Discovery of novel breast and ovarian tumor antigens is also necessary for developing multi-antigen vaccines composed of multiple tumor antigens. Such vaccines are expected to induce diverse immune responses and minimize emergence of antigen-loss variant tumors that are resistant to vaccine-induced immunity. With the exception of melanomas, for most human cancers including breast and ovarian cancers the repertoire of known tumor antigens remains relatively small. In this review we will discuss the importance of characterizing tumor antigens for use in vaccination against cancer and then summarize antigens that have been characterized for human breast and ovarian cancers. We will also emphasize that identification of a novel tumor antigen, while an important first step, needs to be followed by a multi-step process of validation of that antigen. The steps in this validation process are i) to demonstrate that a tumor antigen is over-expressed at a reasonable frequency in primary tumors and in metastases; ii) to demonstrate the immunogenicity of a tumor antigen in an appropriate animal model; iii) to demonstrate its immunogenicity and safety in humans. Additional considerations in this review include: i) discussion of the potential of breast and ovarian tumor antigens as markers for early detection and for monitoring tumor burden in cancer patients; ii) discussion of their potential as prognostic markers of breast and ovarian cancers; and iii) discussion of a unique class of tumor antigens and markers that induce expression of multiple other tumor antigens and markers. Finally, we will discuss the present evidence for potential for autoimmunity that might accompany antitumor vaccination.