bluuebunny/crossref_metadata_2025 huggingface dataset:
mTOR and P70 S6 Kinase Expression in Primary Liver Neoplasms
Authors: Sahin Fikret , Kannangai Rajesh , Adegbola Onikepe , Wang Jianzhou , Su Gloria , Torbenson Michael
Published: September 2005

Purpose: mTOR and P70 S6 kinase (S6K) play a key role in regulating protein translation. The role of mTOR and S6K in hepatocellular carcinoma has not been investigated, but this pathway is of particular interest because an effective inhibitor, rapamycin, is available. This study was undertaken to determine the prevalence and clinicopathological correlates of mTOR pathway activation in hepatocellular carcinoma and to determine whether rapamycin inhibits the pathway in cell culture.

Experimental Design: Total and phosphorylated mTOR and S6K protein expression were studied by immunohistochemistry in hepatocellular carcinomas (n = 73), fibrolamellar carcinomas (n = 13), and hepatic adenomas (n = 15). Results were correlated with tumor growth pattern as defined by the WHO (trabecular, pseudoglandular/acinar, compact, and scirrhous), tumor size, Ki-67 proliferation index, and the modified Edmondson nuclear grade, which has a scale of 1 to 4. HepG2 and Hep3B cell lines were treated with rapamycin to see the effect on proliferation and S6K phosphorylation.

Results: Increased expression of total mTOR was seen in 5% of hepatocellular carcinoma, whereas overexpression of phospho-mTOR was evident in 15% of hepatocellular carcinoma. Phospho-mTOR positivity correlated with increased expression of total S6K, which was found in 45% of cases. Total S6K overexpression was positively correlated with tumor nuclear grade, inversely with tumor size, and was unassociated with the proliferation index or WHO growth pattern. Rapamycin treatment of HepG2 and Hep3B cell lines markedly inhibited cell proliferation and reduced S6K phosphorylation in both cell lines.

Conclusions: The mTOR pathway is activated in a subset of hepatocellular carcinoma. Rapamycin can inhibit proliferation of neoplastic hepatocytes in cell culture.
Flt-4–Positive Endothelial Cell Density and Its Clinical Significance in Non–Small Cell Lung Cancer
Authors: Chen Fengshi , Takenaka Kazumasa , Ogawa Eiji , Yanagihara Kazuhiro , Otake Yosuke , Wada Hiromi , Tanaka Fumihiro
Published: September 2005

Purpose: Experimental studies have revealed that fms-like tyrosine kinase (Flt)-4 plays important roles in lymphangiogenesis in malignant tumors, but the clinical significance remains unclear. We assessed Flt-4 expression in tumor cells and in endothelial cells in correlation with clinical outcomes in non–small cell lung cancer (NSCLC).

Experimental Design: A total of 206 consecutive patients with resected pathological stage I-IIIA NSCLC were reviewed. Expression of Flt-4 was examined immunohistochemically, and Flt-4–positive microvessels were quantitatively evaluated (Flt-4–positive endothelial cell density).

Results: There was no significant correlation between Flt-4–positive endothelial cell density and any characteristic of patients including nodal metastases. A significant correlation between Flt-4–positive endothelial cell density and Flt-4 status in tumor cells was documented (P < 0.001), but there was no significant difference in the mean Flt-4–positive endothelial cell density according to vascular endothelial growth factor-C or -D status in tumor cells. The 5-year survival rate for higher Flt-4–positive endothelial cell density tumor (56.4%) was significantly lower than that of lower Flt-4–positive endothelial cell density tumor (69.0%, P = 0.046); the prognostic significance was enhanced in pIIIA-N2 patients (5-year survival rates, 18.8% for higher Flt-4–positive endothelial cell density tumor and 50.0% for lower Flt-4–positive endothelial cell density tumor, respectively; P = 0.012). A multivariate analysis confirmed that higher Flt-4–positive endothelial cell density was a significant and independent prognostic factor (P = 0.019). CD34-positive vessel density or Flt-4 status in tumor cells was not a significant prognostic factor.

Conclusions: Flt-4–positive endothelial cell density, not Flt-4 status in tumor cells, was a significant prognostic factor in NSCLC.
Prognostic Relevance of Increased Angiogenesis in Osteosarcoma
Authors: Kreuter Michael , Bieker Ralf , Bielack Stefan S. , Auras Tanja , Buerger Horst , Gosheger Georg , Jurgens Heribert , Berdel Wolfgang E. , Mesters Rolf M.
Published: September 2005

Purpose: The purpose of this work was to evaluate the prognostic relevance of microvessel density (MVD) for response to chemotherapy and long-term outcome in osteosarcoma.

Experimental Design: Pretherapeutic tumor biopsies of 60 patients with high-grade central osteosarcoma, who were treated according to multimodal neoadjuvant protocols of the German-Austrian-Swiss Cooperative Osteosarcoma Study Group, were evaluated for intratumoral MVD. MVD was correlated with demographic and tumor-related variables, response, and survival.

Results: The median intratumoral MVD was 52 microvessels per 0.26-mm2 field area (interquartile range, 31–77 microvessels per 0.26-mm2 field area). At a median follow-up period of 3.5 years, patients with a high (>median) MVD had significantly higher 5- and 10-year overall survival rates (84%) than patients with low (≤median) MVD (49%; P = 0.0029). Furthermore, increased relapse-free survival for patients with high MVD (P = 0.0064) was observed. In a subgroup analysis of 44 patients with primary high-grade central osteosarcoma of the extremities without primary metastases and good surgical remission, high MVD was associated with 5- and 10-year overall survival rates of 91% compared with 58% for low MVD (P = 0.034). Cox regression analysis revealed that MVD was an independent prognostic factor for survival. A good response to chemotherapy (histologic grading scale of Salzer-Kuntschik) correlated significantly with a high MVD (P = 0.006).

Conclusions: Increased angiogenesis is a prognostic indicator for higher survival and response rates to chemotherapy in patients with osteosarcoma. Thus, measurement of MVD might be useful in decisions selecting patients for future neoadjuvant treatment.
Loss of Methylthioadenosine Phosphorylase and Elevated Ornithine Decarboxylase Is Common in Pancreatic Cancer
Authors: Subhi Ahmad L. , Tang Baiqing , Balsara Binaifer R. , Altomare Deborah A. , Testa Joseph R. , Cooper Harry S. , Hoffman John P. , Meropol Neal J. , Kruger Warren D.
Published: September 2005

Purpose: Loss of the methylthioadenosine phosphorylase (MTAP) gene at 9p21 is observed frequently in a variety of human cancers. We have shown previously that MTAP can act as a tumor suppressor gene and that its tumor suppressor function is related to its effect on polyamine homeostasis. Ornithine decarboxylase is a key enzyme in the regulation of polyamine metabolism. The aim of this study is to analyze MTAP and ornithine decarboxylase (ODC) expression in primary pancreatic tumor specimens.

Experimental Design: We measured MTAP and ODC activity in protein extracts derived from 30 surgically resected tumor samples and eight normal pancreas samples. In a subset of six samples, we also examined MTAP DNA using interphase fluorescence in situ hybridization. In addition, we examined the effect of the ODC inhibitor difluoromethylornithine on two pancreatic adenocarcinoma-derived cell lines.

Result: MTAP activity was 2.8-fold reduced in adenocarcinomas and 6.3-fold reduced in neuroendocrine tumors compared with control pancreas. Conversely, ODC activity was 3.6-fold elevated in adenocarcinomas and 3.9-fold elevated in neuroendocrine tumors compared with control pancreas. Using interphase fluorescence in situ hybridization, we found in tumor samples that 43 to 75% of the nuclei had lost at least one copy of MTAP locus, indicating that loss of MTAP activity was at least partially because of deletion of the MTAP locus. We also show that inhibition of ODC by difluoromethylornithine caused decreased cell growth and increased apoptosis in two MTAP-deleted pancreatic adenocarcinoma-derived cell lines.

Conclusions: MTAP activity is frequently lost, and ODC activity is frequently elevated in both pancreatic adenocarcinoma and neuroendocrine tumors. Inhibition of ODC activity caused decreased cell growth and increased apoptosis in pancreatic tumor-derived cell lines. These findings suggest that MTAP and polyamine metabolism could be potential therapeutic targets in the treatment of pancreatic cancer.
A Selective Retinoid X Receptor Agonist Bexarotene (Targretin) Prevents and Overcomes Acquired Paclitaxel (Taxol) Resistance in Human Non–Small Cell Lung Cancer
Authors: Yen Wan-Ching , Corpuz Manny R. , Prudente Rene Y. , Cooke Tracy A. , Bissonnette Reid P. , Negro-Vilar Andrés , Lamph William W.
Published: September 2005

Purpose: Paclitaxel is an important anticancer agent for the treatment of non–small cell lung cancer (NSCLC). However, its use in cancer therapy is limited by development of acquired drug resistance. The goal of this study was to determine the effect of bexarotene on development of acquired paclitaxel resistance in NSCLC.

Experimental Design: Human NSCLC Calu3 cells were repeatedly treated in culture with intermittent paclitaxel alone or in combination with continuous bexarotene for 3 months. Thereafter, cells were isolated and characterized for their drug sensitivity in vitro and in vivo.

Results: Repeat exposure to paclitaxel alone resulted in development of paclitaxel resistance with cross-resistance to multidrug resistance P-glycoprotein substrates, whereas the bexarotene/paclitaxel combination prevented the development of drug resistance and the cells remained chemosensitive. Furthermore, paclitaxel resistance could be overcome when the resistant cells were treated with the combination regimen. Fluctuation analysis showed that treatment with bexarotene decreased the rate of spontaneous development of paclitaxel resistance. In vivo, the bexarotene/paclitaxel combination regimen produced a statistically significant decrease in tumor growth in a Calu3 NSCLC xenograft model compared with the single agents (two-tailed, P < 0.05). In addition, paclitaxel-resistant Calu3 tumors treated with the bexarotene/paclitaxel combination showed greater delay in tumor growth compared with those treated with paclitaxel alone.

Conclusions: Our results suggest that bexarotene may offer a novel approach to prevent and overcome paclitaxel resistance in patients with NSCLC.
Detection of Overexpressed and Phosphorylated Wild-Type Kit Receptor in Surgical Specimens of Small Cell Lung Cancer
Authors: Tamborini Elena , Bonadiman Lorena , Negri Tiziana , Greco Angela , Staurengo Samantha , Bidoli Paolo , Pastorino Ugo , Pierotti Marco A. , Pilotti Silvana
Published: September 2005

Purpose: The combinations of various chemotherapeutic drugs currently used to treat advanced small cell lung cancer (SCLC) led to similarly poor survival outcomes, which is why new molecular biology approaches are needed to design and select targeted therapies.

Experimental Design: Thirteen stage I SCLC surgical specimens were screened for c-Kit gene mutations by sequencing whole cDNA and for KIT receptor expression/activation by immunoprecipitation and Western blotting. Both the paraffin-embedded and frozen materials were analyzed by immunocytochemistry, and the stem cell factor cognate ligand was assessed by retrotranscription PCR.

Results: In all cases, we showed the presence of wild-type KIT receptors by analyzing the entire coding sequence, which together with the detection of the cognate ligand stem cell factor, supports the establishment of an autocrine loop. In addition, the KIT receptor was activated/phosphorylated. The immunoprecipitation/Western blotting data fit the observed immunophenotype. Interestingly, comparison of the level of KIT expression was at least 10 times higher in the tumoral specimens than the normal reference lungs.

Conclusions: The KIT molecular profile derived from the analysis of SCLC surgical specimens shows that wild-type KIT is overexpressed and phosphorylated in the presence of stem cell factor. This finding, which is consistent with pathological KIT activation driven by an autocrine loop, is particularly interesting in the light of the recent development of new tyrosine kinase inhibitory drugs, which are highly effective in blocking wild-type KIT receptors.
Inhibition of Metastatic Tumor Growth in Mouse Lung by Repeated Administration of Polyethylene Glycol-Conjugated Catalase
Authors: Hyoudou Kenji , Nishikawa Makiya , Umeyama Yukari , Kobayashi Yuki , Yamashita Fumiyoshi , Hashida Mitsuru
Published: September 2005

Purpose: To develop a novel and effective approach to inhibit tumor metastasis based on controlled delivery of catalase, we first evaluated the characteristics of the disposition and proliferation of tumor cells. Then, we examined the effects of polyethylene glycol-conjugated catalase (PEG-catalase) on tumor metastasis. On the basis of the results obtained, PEG-catalase was repetitively administered to completely suppress the growth of tumor cells.

Experimental Design: Murine melanoma B16-BL6 cells were stably transfected with firefly luciferase gene to obtain B16-BL6/Luc cells. These cells were injected intravenously into syngeneic C57BL/6 mice. PEG-catalase was injected intravenously, and the effect was evaluated by measuring the luciferase activity as the indicator of the number of tumor cells.

Results: At 1 hour after injection of B16-BL6/Luc cells, 60 to 90% of the injected cells were recovered in the lung. The numbers decreased to 2 to 4% at 24 hours, then increased. An injection of PEG-catalase just before inoculation significantly reduced the number of tumor cells at 24 hours. Injection of PEG-catalase at 1 or 3 days after inoculation was also effective in reducing the cell numbers. Daily dosing of PEG-catalase greatly inhibited the proliferation and the number assayed at 14 days after inoculation was not significantly different from the minimal number observed at 1 day, suggesting that the growth had been markedly suppressed by the treatment.

Conclusions: These findings indicate that sustained catalase activity in the blood circulation can prevent the multiple processes of tumor metastasis in the lung, which could lead to a state of tumor dormancy.
Histone Deacetylase Inhibitor Trichostatin A Represses Estrogen Receptor α-Dependent Transcription and Promotes Proteasomal Degradation of Cyclin D1 in Human Breast Carcinoma Cell Lines
Authors: Alao John Patrick , Lam Eric W-F. , Ali Simak , Buluwela Laki , Bordogna Walter , Lockey Peter , Varshochi Rana , Stavropoulou Alexandra V. , Coombes R. Charles , Vigushin David M.
Published: September 2005

Purpose: Estrogen receptor α (ERα)-positive breast cancer cell lines are up to 10 times more sensitive than ERα-negative cell lines to the antiproliferative activity of the histone deacetylase inhibitor trichostatin A (TSA). The purpose of the study was to investigate the mechanisms underlying this differential response.

Experimental Design and Results: In the ERα-positive MCF-7 cell line, TSA repressed ERα and cyclin D1 transcription and induced ubiquitin dependent proteasomal degradation of cyclin D1, leading primarily to G1-S-phase cell cycle arrest. By contrast, cyclin D1 degradation was enhanced but its transcription unaffected by TSA in the ERα-negative MDA-MB-231 cell line, which arrested in G2-M phase. Cyclin D1 degradation involved Skp2/p45, a regulatory component of the Skp1/Cullin/F-box complex; silencing SKP2 gene expression by RNA interference stabilized cyclin D1 and abrogated the cyclin D1 down-regulation response to TSA.

Conclusions: Tamoxifen has been shown to inhibit ERα-mediated cyclin D1 transcription, and acquired resistance to tamoxifen is associated with a shift to ERα-independent cyclin D1 up-regulation. Taken together, our data show that TSA effectively induces cyclin D1 down-regulation through both ERα-dependent and ERα-independent mechanisms, providing an important new strategy for combating resistance to antiestrogens.
Cancer-Associated Expression of
Minichromosome Maintenance 3
Gene in Several Human Cancers and Its Involvement in Tumorigenesis
Authors: Ha Seon-Ah , Shin Seung Min , Namkoong Hong , Lee Heejeong , Cho Goang Won , Hur Soo Young , Kim Tae Eung , Kim Jin Woo
Published: September 2005

Purpose: The purpose of our study was to identify an unique gene that shows cancer-associated expression, evaluates its potential usefulness in cancer diagnosis, and characterizes its function related to human carcinogenesis.

Experimental Design: We used the differential display reverse transcription-PCR method with normal cervical, cervical cancer and metastatic tissues, and cervical cancer cell line to identify genes overexpressed in cancers.

Results: We identified a minichromosome maintenance 3 (MCM3) gene that was overexpressed in various human cancers, including leukemia, lymphoma, and carcinomas of the uterine cervix, colon, lung, stomach, kidney and breast, and malignant melanoma. Western blot and immunohistochemical analyses also revealed that MCM3 protein was elevated in most of human cancer tissues tested. We compared the MCM3 protein expression levels in human cancers with conventional proliferation markers, Ki-67 and proliferating cell nuclear antigen. MCM3 antibody was the most specific for multiple human cancers, whereas proliferating cell nuclear antigen was relatively less effective in specificity, and Ki-67 failed to detect several human cancers. The down-regulation of MCM3 protein level was examined under serum starvation in both normal and cancer cells. Interestingly, MCM3 protein was stable in MCF-7 breast cancer cells even up to 96 hours after serum starvation, whereas it was gradually degraded in normal BJ fibroblast cells. Nude mice who received injections of HEK 293 cells stably transfected with MCM3 formed tumors in 6 weeks.

Conclusions: Our study indicates that determination of MCM3 expression level will facilitate the assessment of many different human malignancies in tumor diagnosis, and MCM3 is involved in multiple types of human carcino-genesis.
Antitumor Efficacy of Oblimersen Bcl-2 Antisense Oligonucleotide Alone and in Combination with Vinorelbine in Xenograft Models of Human Non–Small Cell Lung Cancer
Authors: Hu YanPing , Bebb Gwyn , Tan Sophia , Ng Rebecca , Yan Hong , Sartor Jason R. , Mayer Lawrence D. , Bally Marcel B.
Published: September 2005

Overexpression of Bcl-2 protein in cancer cells can inhibit programmed cell death and engender chemoresistance. Reducing Bcl-2 protein levels by using antisense oligonucleotides targeting the gene message can increase the sensitivity of cancer cells to cytotoxic agents. The objective of this work was to investigate the antitumor efficacy of the Bcl-2 antisense oligonucleotide oblimersen (Genasense; G3139), alone and in combination with vinorelbine (VNB), in an ectopic and orthotopic xenograft model of NCI-H460 human non–small-cell lung cancer. In addition to assessing therapeutic effect, Bcl-2 protein expression in tumor tissue isolated from lung and heart was measured. In the ectopic xenograft model, oblimersen at 5 and 10 mg/kg significantly inhibited tumor growth compared with saline-treated control groups, and furthermore, the antitumor effect of oblimersen was associated with down-regulation of Bcl-2 protein in isolated tumor tissue. Moreover, the combination of oblimersen with VNB was more active in inhibiting tumor growth than either drug used alone. In the orthotopic model, oblimersen treatment (5 mg/kg) increased the median survival time of mice to 33 days in comparison with a median survival time of 21 days in the control animals. With this model, the anticancer effect was demonstrated by assessing tumor growth in lung and heart tissues by hematoxylin and eosin staining and Bcl-2 expression by immunohistochemistry. When VNB at 5 mg/kg was combined with oblimersen administered at 5 mg/kg, 33% of mice survived more than 90 days. These data suggest that the combination of oblimersen and VNB may provide enhanced antitumor activities against non–small-cell lung cancer.
Antitumor Activity of Small Interfering RNA/Cationic Liposome Complex in Mouse Models of Cancer
Authors: Yano Junichi , Hirabayashi Kazuko , Nakagawa Shin-ichiro , Yamaguchi Tohru , Nogawa Masaki , Kashimori Isao , Naito Haruna , Kitagawa Hidetoshi , Ishiyama Kouichi , Ohgi Tadaaki , Irimura Tatsuro
Published: September 2005

Purpose: The RNA interference effect is an alternative to antisense DNA as an experimental method of down-regulating a specific target protein. Although the RNA interference effect, which is mediated by small interfering RNA (siRNA) or micro-RNA, has potential application to human therapy, the hydrodynamic method usually used for rapid administration of oligonucleotides is unsuitable for use in humans. In this study, we have investigated the antitumor activity of a synthetic siRNA, B717, which is sequence specific for the human bcl-2 oncogene, complexed with a novel cationic liposome, LIC-101.

Experimental Design: In a mouse model of liver metastasis, we administered B717/LIC-101 by bolus intravenous injection, adjusting the rate and volume of administration to what is feasible in human therapy. In a mouse model bearing prostate cancer in which the cells were inoculated under the skin, B717/LIC-101 was administered subcutaneously around the tumor.

Results: The B717/LIC-101 complex inhibited the expression of bcl-2 protein and the growth of tumor cell lines in vitro in a sequence-specific manner in the concentration range of 3 to 100 nmol/L. Furthermore, the complex had a strong antitumor activity when administered intravenously in the mouse model of liver metastasis. B717 (siRNA) was shown to be delivered to tumor cells in the mouse liver, but only when complexed with LIC-101. The complex also inhibited tumor cell growth in the mouse model bearing prostate cancer.

Conclusions: By combining siRNA with our cationic liposome, we overcame the difficulty of administering siRNA to animals in ways that can be applied in human therapy. Although our siRNA/liposome complex is not yet in clinical trials, it is expected to provide a novel siRNA therapy for cancer patients.
Selective Induction of Apoptosis with Proton Pump Inhibitor in Gastric Cancer Cells
Authors: Yeo Marie , Kim Dong-Kyu , Kim Young-Bae , Oh Tae Young , Lee Jong-Eun , Cho Sung Won , Kim Hugh Chul , Hahm Ki-Baik
Published: September 2005

Purpose: To survive in an ischemic microenvironment with a lower extracellular pH, ability to up-regulate proton extrusion is critical for cancer cell survival. Gastric H+/K+-ATPase exchanges luminal K+ for cytoplasmic H+ and is the enzyme primarily responsible for gastric acidification. On the basis of the fact that blocking the clearance of acidic metabolites are known to induce the cell death, we hypothesized that pantoprazole (PPZ), one of gastric H+/K+-ATPase inhibitors used frequently to treat acid-related diseases, could inhibit growth of tumor cells.

Experimental Design: Genomic DNA fragmentation, terminal deoxynucleotidyl transferase (Tdt)-mediated nick end labeling assay, and annexin V staining were performed to detect PPZ-induced apoptosis. Mitogen-activated protein kinase activation and heat shock proteins expression were determined by immunoblot with specific antibodies. The antitumor effect of PPZ was evaluated in vivo by a xenograft model of nude mice.

Results: After PPZ treatment, apoptotic cell death was seen selectively in cancer cells and was accompanied with extracellular signal-regulated kinase deactivation. By contrast, normal gastric mucosal cells showed the resistance to PPZ-induced apoptosis through the overexpression of antiapoptotic regulators including HSP70 and HSP27. In a xenograft model of nude mice, administration of PPZ significantly inhibited tumorigenesis and induced large-scale apoptosis of tumor cells.

Conclusions: PPZ selectively induced in vivo and in vitro apoptotic cell death in gastric cancer, suggesting that proton pump inhibitors could be used for selective anticancer effects.
Clinical Significance of Micrometastatic Cells Detected by E48 (Ly-6D) Reverse Transcription-Polymerase Chain Reaction in Bone Marrow of Head and Neck Cancer Patients
Authors: Colnot David R. , Nieuwenhuis Eline J. C. , Kuik Dirk J. , Leemans C. René , Dijkstra Janny , Snow Gordon B. , van Dongen Guus A. M. S. , Brakenhoff Ruud H.
Published: September 2005

Purpose: Despite improvements in locoregional treatment of head and neck squamous cell carcinoma (HNSCC), local and distant failure rates remain high. The strongest prognostic indicator of HNSCC is the presence of lymph node metastases in the neck, but the value of this indicator has limitations when using for the individual patient. The presence of micrometastatic cells in bone marrow has been shown to be a putative prognostic indicator in HNSCC and other epithelial malignancies, which might allow more accurate staging and selection of patients for whom adjuvant or experimental therapy is recommended. The gene encoding the E48 antigen is selectively expressed by HNSCC, and the detection of E48 transcripts in bone marrow by reverse transcription-polymerase chain reaction (RT-PCR) presumably represents the presence of micrometastatic cells. The purpose of this study was to determine the association between the presence of micrometastatic cells in bone marrow of HNSCC patients and clinical outcome.

Experimental Design: A total of 162 patients treated surgically for primary HNSCC underwent a single bone marrow aspiration from the upper iliac crest for detection of micrometastatic cells using E48 RT-PCR. In total, 139 patients were evaluable. The primary statistical endpoints were disease-free survival and distant metastasis-free survival. In addition, bone marrow samples of 30 noncancer controls were evaluated.

Results: E48 RT-PCR indicated the presence of micrometastatic cells in the bone marrow in 56 of 139 (40%) of the HNSCC patients and 0 of 30 of the noncancer controls (P < 0.0001). The presence of micrometastatic cells had no significant influence on disease-free survival or distant metastasis-free survival for the whole group of HNSCC patients (P = 0.1460 and P = 0.2912, respectively). For patients with ≥2 lymph node metastases, however, the presence of micrometastatic cells was associated with a poor distant metastasis-free survival (P = 0.0210).

Conclusions: The presence of micrometastatic cells in bone marrow of HNSCC patients with ≥2 lymph node metastases is correlated with a poor distant metastasis-free survival. In this subgroup of HNSCC patients, E48 RT-PCR seems to be a valuable tool to identify patients who are at increased risk for development of distant metastases and therefore might benefit from experimental adjuvant systemic therapy.
Circulating Tumor Cells in Patients with Breast Cancer Dormancy
Authors: Meng Songdong , Tripathy Debasish , Frenkel Eugene P. , Shete Sanjay , Naftalis Elizabeth Z. , Huth James F. , Beitsch Peter D. , Leitch Marilyn , Hoover Susan , Euhus David , Haley Barbara , Morrison Larry , Fleming Timothy P. , Herlyn Dorothee , Terstappen Leon W. M. M. , Fehm Tanja , Tucker Thomas F. , Lane Nancy , Wang Jianqiang , Uhr Jonathan W.
Published: September 2005

Purpose: The purpose of this study was to test the hypothesis that circulating tumor cells (CTCs) are present in patients many years after mastectomy without evidence of disease and that these CTCs are shed from persisting tumor in patients with breast cancer dormancy.

Experimental Design: We searched for CTCs in 36 dormancy candidate patients and 26 age-matched controls using stringent criteria for cytomorphology, immunophenotype, and aneusomy.

Results: Thirteen of 36 dormancy candidates, 7 to 22 years after mastectomy and without evidence of clinical disease, had CTCs, usually on more than one occasion. Only 1 of 26 controls had a possible CTC (no aneusomy). The statistical difference of these two distributions was significant (exact P = 0.0043). The CTCs in patients whose primary breast cancer was just removed had a half-life measured in 1 to 2.4 hours.

Conclusions: The CTCs that are dying must be replenished every few hours by replicating tumor cells somewhere in the tissues. Hence, there appears to be a balance between tumor replication and cell death for as long as 22 years in dormancy candidates. We conclude that this is one mechanism underlying tumor dormancy.
Low Levels of Estrogen Receptor β Protein Predict Resistance to Tamoxifen Therapy in Breast Cancer
Authors: Hopp Torsten A. , Weiss Heidi L. , Parra Irma S. , Cui Yukun , Osborne C. Kent , Fuqua Suzanne A. W.
Published: September 2005

Purpose: Breast cancer is a hormone-dependent cancer, and the presence of estrogen receptor α (ER-α) in tumors is used clinically to predict the likelihood of response to hormonal therapies. The clinical value of the second recently identified ER isoform, called ER-β, is less clear, and there is currently conflicting data concerning its potential role as a prognostic or predictive factor.

Experimental Design: To assess whether ER-β expression is associated with clinical outcome, protein levels were measured by immunoblot analysis of a retrospective bank of tumor cell lysates from 305 axillary node-positive patients. A total of 119 received no adjuvant therapy, and 186 were treated with tamoxifen only. The median follow-up time was 65 months. Univariate and multivariate Cox regression modeling was done to assess the prognostic and predictive significance of ER-β expression.

Results: Expression of ER-β protein did not correlate significantly with any other clinical variables, including ER and progesterone levels (as measured ligand binding assay), tumor size, age, or axillary nodal status. In the untreated population, those patients whose tumors who expressed both receptor isoforms exhibited the most favorable outcome as compared with those patients who had lost ER-α expression. However, there was no association between ER-β levels alone and either disease-free or overall survival in the untreated patient population. In contrast, in both univariate and multivariate analyses, high levels of ER-β predicted an improved disease-free and overall survival in patients treated with adjuvant tamoxifen therapy.

Conclusions: These findings provide evidence that ER-β may be an independent predictor of response to tamoxifen in breast cancer. Furthermore, these results suggest that ER-β may influence tumor progression in ways different from those mediated by the ER-α isoform.
Dietary Flaxseed Enhances the Inhibitory Effect of Tamoxifen on the Growth of Estrogen-Dependent Human Breast Cancer (MCF-7) in Nude Mice
Authors: Chen Jianmin , Hui Evon , Ip Terence , Thompson Lilian U.
Published: September 2005

Purpose: This study determined the effect of 10% dietary flaxseed (FS) and tamoxifen (TAM), alone and in combination, on the growth of estrogen-dependent human breast cancer (MCF-7) in athymic mice with or without 17β-estradiol (E2) supplementation.

Experimental Design: Ovariectomized mice received injection with MCF-7 cells, were implanted with an E2 pellet (1.7 mg), and fed the basal diet (BD). When tumor reached ∼40 mm2, the E2 implant was removed, and mice were randomized to the following groups and maintained at either low (E2 pellet removed) or high E2 level (new E2 pellet implanted) for 6 weeks: (a) positive control with new E2 pellet, fed BD, (b) negative control with no E2 implant, fed BD, (c) TAM group with TAM pellet (5 mg) implant, fed BD, (d) FS group fed 10% FS, (e) FS+TAM group with TAM implant, fed 10% FS. Tumor growth was monitored weekly.

Results: At low E2 level, FS regressed the pretreatment tumor size by 74%. TAM regressed tumor initially but later induced an increase so that the tumor size was finally similar to the pretreatment size. A tumor regression >53% was induced by FS+TAM than by TAM alone. At high E2 level, FS, TAM, and FS+TAM inhibited the tumor growth by 22, 41, and 50%, respectively, compared with the positive control. Decreased tumor size was attributable to reduced tumor cell proliferation and increased apoptosis.

Conclusions: FS inhibited the growth of human estrogen-dependent breast cancer and strengthened the tumor-inhibitory effect of TAM at both low and high E2 levels.
Apurinic Endonuclease Activity in Adult Gliomas and Time to Tumor Progression after Alkylating Agent-Based Chemotherapy and after Radiotherapy
Authors: Bobola Michael S. , Emond Mary J. , Blank A. , Meade Elizabeth H. , Kolstoe Douglas D. , Berger Mitchel S. , Rostomily Robert C. , Silbergeld Daniel L. , Spence Alexander M. , Silber John R.
Published: September 2005

Purpose: Apurinic/apyrimidinic endonuclease (Ap endo) is a key DNA repair enzyme that cleaves DNA at cytotoxic abasic sites caused by alkylating agents and radiation. We have observed that human glioma cells deficient in Ap endo activity are hypersensitive to clinically used alkylators (Silber et al., Clin Cancer Res 2002;8:3008.). Here we examine the association of glioma Ap endo activity with clinical response after alkylating agent-based chemotherapy or after radiotherapy.

Experimental Design: Cox proportional hazards regression models were used to analyze the relationship of Ap endo activity with time to tumor progression (TTP).

Results: In a univariate model with Ap endo activity entered as a continuous variable, the hazard ratio (HR) for progression after alkylator therapy in 30 grade III gliomas increased by a factor of 1.061 for every 0.01 increase in activity (P = 0.013). Adjusting for age, gender, extent of resection, and prior treatment strengthened slightly the association (HR = 1.094; P = 0.003). Similarly, the HR for progression after radiotherapy in 44 grade II and III tumors increased by a factor of 1.069 (P = 0.008). Adjusting for the aforementioned variables had little effect on the association. In contrast, we observed no association between activity and TTP in grade IV gliomas after either alkylator therapy in 34 tumors or radiotherapy in 26 tumors.

Conclusions: Our data suggest that Ap endo activity mediates resistance to alkylating agents and radiation and may be a useful predictor of progression after adjuvant therapy in a subset of gliomas.
Sensitization of Tumor-Associated Endothelial Cell Apoptosis by the Novel Vascular-Targeting Agent ZD6126 in Combination with Cisplatin
Authors: Goto Hisatsugu , Yano Seiji , Matsumori Yuka , Ogawa Hirohisa , Blakey David C. , Sone Saburo
Published: September 2005

Purpose: ZD6126 is a novel vascular-targeting agent that selectively disrupts the tubulin cytoskeleton of endothelial cells. In the immature vessels characteristic of tumor vasculature, this leads to endothelial cell contraction, blood vessel congestion, and, consequently, tumor cell death. ZD6126 has been shown to delay tumor growth in a range of xenograft models. The antitumor effect of ZD6126 can be increased in combination with cisplatin or radiation therapy, although the precise mechanism of this enhancement has not been demonstrated. ZD6126 treatment has also been shown to inhibit lung metastasis, and the present study has explored the potential to increase the antimetastatic effect of ZD6126 by combining with cisplatin, and the underlining mechanism has been investigated.

Experimental Design: Human lung adenocarcinoma PC14PE6 cells were injected into the tail vein of nude mice. Five weeks after injection animals were treated with ZD6126 (200 mg/kg i.p.), cisplatin (6 mg/kg i.v.), or a combination of the two agents. The animals were sacrificed 24 hours later, and the extent of lung metastases and the presence of apoptotic cells were assessed.

Results: Histologic analysis revealed that the ZD6126/cisplatin combination resulted in a 2 to 4-fold increase in the total number of tumor-associated apoptotic cells compared with either treatment alone. ZD6126 alone induced apoptosis of tumor-associated endothelial cells in tumors, and the extent of apoptosis was increased 2-fold in combination with cisplatin. The lung weight was significantly reduced, and the number of metastatic nodules significantly was lower in the combined treatment group than in the control group.

Conclusions: These data suggest that the antimetastatic effect of the vascular-targeting agent ZD6126 can be increased by use in combination with cisplatin, which increases the incidence of endothelial cell apoptosis.
Application of a Macromolecular Contrast Agent for Detection of Alterations of Tumor Vessel Permeability Induced by Radiation
Authors: Kobayashi Hisataka , Reijnders Koen , English Sean , Yordanov Alexander T. , Milenic Diane E. , Sowers Anastasia L. , Citrin Deborah , Krishna Murali C. , Waldmann Thomas A. , Mitchell James B. , Brechbiel Martin W.
Published: September 2005

Permeability of tumor vasculature can be a major barrier to successful drug delivery, particularly for high molecular weight agents such as monoclonal antibodies and their diagnostic or therapeutic conjugates. In this study, changes in permeability of SCCVII tumor vessels after radiation treatment were evaluated by dynamic magnetic resonance imaging as a function of time after irradiation using a generation-8 polyamidoamine dendrimer (G8-Gd-D)-based magnetic resonance imaging contrast agent shown previously to be confined to tumor blood vessels. Tumor irradiation consisted of either single doses (2–15 Gy) or various daily fractionated doses (5 days). A single radiation dose of 15 Gy resulted in significant transient image enhancement of the tumor tissue with a maximum occurring between 7 and 24 hours after radiation treatment. No observable enhancement was recorded for fractionated radiation doses. Use of dynamic magnetic resonance imaging coupled with G8-Gd-D provides an exquisite methodology capable of defining the timing of enhanced permeability of macromolecules in tumors after irradiation. Such information might be applied to optimize the efficacy of subsequent or concurrent therapies including radiolabeled antibodies or other anticancer agents in combination with external beam therapies.
S-1 Plus Cisplatin Combination Chemotherapy in Patients with Advanced Non–Small Cell Lung Cancer
Authors: Ichinose Yukito , Yoshimori Kozo , Sakai Hiroshi , Nakai Yushi , Sugiura Takahiko , Kawahara Masaaki , Niitani Hisanobu
Published: September 2005

Purpose: To evaluate the efficacy and toxicity of a novel combination chemotherapeutic regimen including cisplatin with an oral anticancer agent, S-1 that consisted of tegafur, 5-chloro-2, 4-dihydroxypyridine, and potassium oxonate, for non–small-cell lung cancer (NSCLC) patients.

Experimental Design: In this phase II trial, patients with locally advanced and metastatic NSCLC were treated with the oral administration of S-1 at 40 mg/m2 twice a day for 21 consecutive days while cisplatin (60 mg/m2) was administered intravenously on day 8. This schedule was repeated every 5 weeks.

Results: Of 56 patients enrolled in the study, 55 patients were eligible and analyzed. The median number of cycles administered was 3 (range, 1–12 cycles). Among these 55 patients, one complete response and 25 partial responses were observed with an overall response rate of 47% (95% confidence interval, 34–61%). The median survival time was 11 months and the 1-year survival rate was 45%. Hematologic toxicities of grades 3 and 4 included neutropenia (29%) and anemia (22%). No grade 4 nonhematologic toxicity was observed. Grade 3 toxicity included anorexia (13%), vomiting (7%), or diarrhea (7%).

Conclusions: S-1 plus cisplatin combination chemotherapy showed a promising effectiveness with acceptable toxicity rates in patients with advanced NSCLC. These results warrant further investigations of this regimen including a randomized controlled trial for its use as a first line treatment for NSCLC.
Lack of Impact of the Loss of Constitutive Folate Receptor α Expression, Achieved by RNA Interference, on the Activity of the New Generation Antifolate Pemetrexed in HeLa Cells
Authors: Chattopadhyay Shrikanta , Wang Yanhua , Zhao Rongbao , Goldman I. David
Published: September 2005

Pemetrexed [PMX (Alimta)] is a new generation antifolate with activity in a variety of solid tumors. It is an excellent substrate for most folate transporters, notably the reduced folate carrier (RFC) and folate receptor (FR)-α. The role of FR-α in PMX pharmacological activity is uncertain. Whereas high-level expression may enhance the activity of this agent, it is not clear what role constitutive levels of this transporter contribute to PMX activity. In this study, constitutive levels of FR-α expression were abolished by small interfering RNA-induced silencing in HeLa cells and RFC-null HeLa R5 cells as confirmed by Northern blotting, immunohistochemistry, and cell surface binding. PMX growth inhibition was unchanged in HeLa and R5 cells in the absence of FR-α expression. Loss of FR-α expression did not decrease net accumulation of PMX in either wild-type or RFC-null HeLa cells. Likewise, folate pools in wild-type HeLa cells were not decreased by FR-α gene silencing and were negligibly affected in the RFC-null R5 subline grown with 5-formyltetrahydrofolate. FR-α surface binding in HeLa cells was shown to be greater than that in a variety of other human solid tumor cell lines. Hence, constitutively expressed FR-α in HeLa cells does not contribute to PMX activity in the presence or absence of RFC function. This is likely the case in many human solid tumor cell lines.
Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand–Induced Apoptosis Is Inhibited by Bcl-2 but Restored by the Small Molecule Bcl-2 Inhibitor, HA 14-1, in Human Colon Cancer Cells
Authors: Sinicrope Frank A. , Penington Robert C. , Tang Xi Ming
Published: September 2005

Purpose: Tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent that induces apoptosis in multiple tumor cell types while sparing most normal cells. We determined the effect of ectopic Bcl-2 expression on TRAIL-induced apoptosis and whether the small molecule Bcl-2 inhibitor, HA14-1, could increase TRAIL sensitivity.

Experimental Design: SW480 human colon cancer cells were stably transfected with the PC3-Bcl-2 plasmid or vector alone. Cells were incubated with recombinant human TRAIL ± HA14-1 or caspase-9 inhibitor (Z-LEHD-FMK). Apoptosis was analyzed by Annexin V-fluorescein isothiocyanate labeling and DNA fragmentation factor 45 (DFF45) cleavage. Clonigenic survival was also studied. Caspase activation was determined by immunoblotting or colorimetric assay. The cytosolic expression of Bid, Bax, and XIAP and release of cytochrome c and Smac/DIABLO were determined by immunoblotting.

Results: Bcl-2 overexpression partially protected SW480 cells from a dose-dependent induction of apoptosis by TRAIL, as did a caspase-9 inhibitor, and increased their clonogenic survival. Bcl-2 overexpression attenuated TRAIL-induced cleavage of caspase-8, indicating its activation upstream and downstream of mitochondria, as well as cleavage of Bid and caspase-3. Bcl-2 inhibited TRAIL-induced Bax translocation, cytosolic release of cytochrome c and Smac/DIABLO, and the downstream cleavage of XIAP and DFF45. Coadministration of HA14-1 and TRAIL increased apoptosis in SW480/Bcl-2 cells by restoring Bax redistribution and cytochrome c release.

Conclusions: Bcl-2 confers apoptosis resistance to TRAIL by inhibiting a mitochondrial amplification step and by inactivating downstream XIAP in SW480 cells. HA14-1 reversed Bcl-2–mediated TRAIL resistance, suggesting a novel strategy for increasing TRAIL sensitivity in Bcl-2–overexpressing colon cancers.
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
Authors: Bhattacharya Arup , Tóth Károly , Mazurchuk Richard , Spernyak Joseph A. , Slocum Harry K. , Pendyala Lakshmi , Azrak Rami , Cao Shousong , Durrani Farukh A. , Rustum Youcef M.
Published: September 2005

Purpose: Combination chemotherapy with irinotecan (CPT-11; 50 mg/kg/week × 4 intravenously), followed 24 hour later by 5-fluorouracil (50 mg/kg/week × 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/×400), whereas FaDu is uniformly poorly differentiated with higher microvessel density (19/×400). 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 14C-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 (∼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 14C-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.
Association of Epigenetic Inactivation of
RASSF1A
with Poor Outcome in Human Neuroblastoma
Authors: Yang Qiwei , Zage Peter , Kagan David , Tian Yufeng , Seshadri Roopa , Salwen Helen R. , Liu Shuqing , Chlenski Alexandre , Cohn Susan L.
Published: September 2005

Purpose: To investigate the prevalence and potential clinical significance of epigenetic aberrations in neuroblastoma (NB).

Experimental Design: The methylation status of 11 genes that are frequently epigenetically inactivated in adult cancers was assayed in 13 NB cell lines. The prevalence of RASSF1A and TSP-1 methylation was also analyzed in 56 NBs and 5 ganglioneuromas by methylation-specific PCR. Associations between the methylation status of RASSF1A and TSP-1 and patient age, tumor stage, tumor MYCN status, and patient survival were evaluated.

Results: Epigenetic changes were detected in all 13 NB cell lines, although the pattern of gene methylation varied. The putative tumor suppressor gene RASSF1A was methylated in all 13 cell lines, and TSP-1 and CASP8 were methylated in 11 of 13 cell lines. Epigenetic changes of DAPK and FAS were detected in only small numbers of cell lines, whereas none of the cell lines had methylation of p16, p21, p73, RAR-β2, SPARC, or TIMP-3. RASSF1A was also methylated in 70% of the primary NB tumors tested, and TSP-1 methylation was detected in 55% of the tumors. RASSF1A methylation was significantly associated with age >1 year (P < 0.01), high-risk disease (P < 0.016), and poor survival (P < 0.001). In contrast, no association between TSP-1 methylation and prognostic factors or survival was observed.

Conclusions: Our results suggest that epigenetic inactivation of RASSF1A may contribute to the clinically aggressive phenotype of high-risk NB.