Table of Contents

Volume 13, Issue 12

  October 2012

  Pages 1141 - 1228

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 Issue Catalogue (MARC XML)

JOURNAL CLUB

How do you want your steak prepared? The impact of meat consumption and preparation on prostate cancer

William D. Figg, II
Pages 1141 - 1142
http://dx.doi.org/10.4161/cbt.21463
Abstract | Full Text | PDF

Numerous epidemiological studies have suggested dietary factors may alter the risk of prostate cancer. Punnen and colleagues have conducted a case-control study focused on aggressive prostate cancer (N = 982), where not only details on meat consumption were collected, but also meat preparation was captured. A multivariate logistic regression model was used to assess the association between meat consumption, grilled meat consumption, doneness level, mutagens and aggressive prostate cancer. High consumption of processed meat, including ground beef, was associated with aggressive prostate cancer. Ground beef showed the strongest association (overall risk, OR = 2.30, 95% confidence interval, CI: 1.39–3.81; P-trend = 0.002). Well-done meat conferred a higher risk of aggressive prostate cancer. Interestingly, the consumption of rare or less cooked meat was not associated with an increased risk of prostate cancer. When the investigators evaluated the estimated meat mutagens produced by cooking at high temperatures, they identified an increased risk with MelQx and DiMelQx, OR = 1.69 95% CI: 1.08–2.64, P-trend = 0.02 and OR = 1.53 95% CI: 1.00–2.35, P-trend = 0.005, respectively.




REVIEW

Open Access Article

Regulation of the human TRAIL gene

Joshua E. Allen and Wafik S. El-Deiry
Pages 1143 - 1151
http://dx.doi.org/10.4161/cbt.21354
Abstract | Full Text | PDF

TRAIL is a member of the TNF superfamily that induces tumor-selective cell death by engaging the pro-apoptotic death receptors DR4 and DR5. The antitumor potential of the TRAIL pathway has been targeted by several therapeutic approaches including recombinant TRAIL and TRAIL-receptor agonist antibodies among others. Interest in sensitizing tumor cells to TRAIL-mediated apoptosis has driven investigations of TRAIL-receptor gene regulation, though regulation of the TRAIL gene has been less studied. Physiologically, TRAIL serves as a pro-apoptotic effector molecule in the immune surveillance of cancer that is conditionally expressed by immune cells upon stimulation via an interferon-response element that was identified in early studies of the TRAIL gene promoter. Here, we map the TRAIL gene promoter and review studies of TRAIL gene regulation that involve several modalities of gene regulation including transcription factors, epigenetics, single-nucleotide polymorphisms and functionally distinct isoforms.




RESEARCH PAPERS

Open Access Article

CDX2 serves as a Wnt signaling inhibitor and is frequently methylated in lung cancer

Xuefeng Liu, Xiaomei Zhang, Qimin Zhan, Malcolm V. Brock, James G. Herman and Mingzhou Guo
Pages 1152 - 1157
http://dx.doi.org/10.4161/cbt.21344
Abstract | Full Text | PDF

Aberrant promoter region hypermethylation of upstream transcription factors may be responsible for silencing entire anti-neoplastic gene networks. In this study, we explored whether transcription factor coding gene, caudal-related homeobox 2 (CDX2), is silenced by promoter hypermethylation in lung cancer, and examined its potential tumor-suppressive functions. Semi-quantitative RT-PCR showed that four of six lung cancer cell lines exhibited no or weak CDX2 expression. Expression of CDX2 was correlated to CDX2 promoter region methylation status, as determined by methylation-specific PCR (MSP) and bisulfite sequencing. Restoration of CDX2 expression was induced by treatment with demethylating drug 5-aza-2'-deoxycytidine (5-AZA) in lung cancer cell lines. Methylation of CDX2 was common in human primary lung cancer (61 of 110 tumors, 55.45%), but no methylation was found in normal lung tissues. Re-expression of CDX2 suppressed lung cancer cell proliferation and blocked cells in G1 phase. β-catenin/TCF activity and downstream genes expression were inhibited by re-expression of CDX2, and increased by depletion of CDX2. In conclusion, CDX2 is frequently methylated in lung cancer, and expression of CDX2 is regulated by promoter region hypermethylation. CDX2 may serve as a tumor suppressor in lung cancer and inhibits lung cancer cell proliferation by suppressing Wnt signaling.

Successful engraftment of human acute lymphoblastic leukemia cells in NOD/SCID mice via intrasplenic inoculation

Na Wang, Liang Huang, Di Wang, Jin Wang, Lijun Jiang, Kuangguo Zhou, Yunfan Yang, Danmei Xu and Jianfeng Zhou
Pages 1158 - 1164
http://dx.doi.org/10.4161/cbt.21345
Abstract | Full Text | PDF

Acute lymphoblastic leukemia (ALL) is a heterogeneous disorder, and primary drug resistance and relapse are thought to be the main causes for treatment failure in ALL patients. For these refractory or relapsed patients, there is an increasing demand to identify novel therapeutic approaches, which will highly rely on the use of xenotransplantation models in translational research. Given the critical role that the spleen plays in the hematopoiesis and lymphopoiesis in adult mice, intrasplenic inoculation of ALL cells into immunodeficient mice may represent a feasible route for leukemic xenotransplantation. In the present study, engraftments via intrasplenic inoculation in anti-mCD122 mAb conditioned NOD/SCID mice were achieved in 5 out of 11 cases, and the engrafted cells reconstituted a complete leukemic phenotype. The engrafted cells sustained the self-renewal capacity of leukemia-initiating cells as tested by serial xenotransplantation and can be used for evaluation of antileukemic drugs. These data suggest that the combination of intrasplenic inoculation and the targeted depletion of CD122⁺ cells could provide a novel approach for the xenotransplantation of ALL cells in NOD/SCID mice. Furthermore, this model can be used for stem cell research, long-term analysis of engraftment kinetics and in vivo drug tests.

The impact of PTEN tumor suppressor gene on acquiring resistance to tamoxifen treatment in breast cancer patients

Nikola Tanic, Zorka Milovanovic, Nasta Tanic, Radan Dzodic, Zorica Juranic, Snezana Susnjar, Vesna Plesinac-Karapandzic, Svetislav Tatic, Tatjana Dramicanin, Radoslav Davidovic and Bogomir Dimitrijevic
Pages 1165 - 1174
http://dx.doi.org/10.4161/cbt.21346
Abstract | Full Text | PDF

Tamoxifen is a standard therapeutical treatment in patients with estrogen receptor positive breast carcinoma. However, less than 50% of estrogen receptor positive breast cancers do not respond to tamoxifen treatment whereas 40% of tumors that initially respond to treatment develop resistance over time. The underlying mechanisms for tamoxifen resistance are probably multifactorial but remain largely unknown. The primary aim of this study was to investigate the impact of PTEN tumor suppressor gene on acquiring resistance to tamoxifen by analyzing loss of heterozygosity (LOH) and immunohystochemical expression of PTEN in 49 primary breast carcinomas of patients treated with tamoxifen as the only adjuvant therapy. The effect of PTEN inactivation on breast cancer progression and disease outcome was also analyzed. Reduced or completely lost PTEN expression was observed in 55.1% of samples, while 63.3% of samples displayed LOH of PTEN gene. Inactivation of PTEN immunoexpression significantly correlated with the PTEN loss of heterozygosity, suggesting LOH as the most important genetic mechanism for the reduction or complete loss of PTEN expression in primary breast carcinoma. Most importantly, LOH of PTEN and consequential reduction of its immunoexpression showed significant correlation with the recurrence of the disease. Besides, our study revealed that LOH of PTEN tumor suppressor was significantly associated with shorter disease free survival, breast cancer specific survival and overall survival. In summary, our results imply that LOH of PTEN could be used as a good prognostic characteristic for the outcome of breast cancer patients treated with tamoxifen.

The inhibitory effect of MSCs expressing TRAIL as a cellular delivery vehicle in combination with cisplatin on hepatocellular carcinoma

Bo Zhang, Hong Shan, Dan Li, Zheng-Ran Li, Kang-Shun Zhu and Zai-Bo Jiang
Pages 1175 - 1184
http://dx.doi.org/10.4161/cbt.21347
Abstract | Full Text | PDF

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been demonstrated to induce cell apoptosis in many types of tumors, while many hepatocellular carcinoma (HCC) cells display high resistance to TRAIL. Another outstanding limitation of TRAIL is the short half-life in vivo. Stem cell-based therapies provide a promising approach for the treatment of many types of tumors because of the ability of tropism. Therefore, as a new therapeutic strategy, the combination of chemotherapeutic agents and TRAIL gene modified MSCs (TRAIL-MSCs) would improve the therapeutic efficacy of HCC in vivo. This is the first time to show the potential of combination of chemotherapeutic agents and MSCs as a gene vector in the therapy of HCC.

Analysis of glutamine dependency in non-small cell lung cancer: GLS1 splice variant GAC is essential for cancer cell growth

A. Pieter J. van den Heuvel, Junping Jing, Richard F. Wooster and Kurtis E. Bachman
Pages 1185 - 1194
http://dx.doi.org/10.4161/cbt.21348
Abstract | Full Text | PDF

One of the hallmarks of cancer is metabolic deregulation. Many tumors display increased glucose uptake and breakdown through the process of aerobic glycolysis, also known as the Warburg effect. Less studied in cancer development and progression is the importance of the glutamine (Gln) pathway, which provides cells with a variety of essential products to sustain cell proliferation, such as ATP and macromolecules for biosynthesis. To this end Gln dependency was assessed in a panel of non-small cell lung cancer lines (NSCLC). Gln was found to be essential for the growth of cells with high rates of glutaminolysis, and after exploring multiple genes in the Gln pathway, GLS1 was found to be the key enzyme associated with this dependence. This dependence was confirmed by observing the rescue of decreased growth by exogenous addition of downstream metabolites of glutaminolysis. Expression of the GLS1 splice variant KGA was found to be decreased in tumors compared with normal lung tissue. Transient knock down of GLS1 splice variants indicated that loss of GAC had the most detrimental effect on cancer cell growth. In conclusion, NSCLC cell lines depend on Gln for glutaminolysis to a varying degree, in which the GLS1 splice variant GAC plays an essential role and is a potential target for cancer metabolism-directed therapy.

Adenovirus-mediated expression of mutated forkhead human transcription like-1 suppresses tumor growth in a mouse melanoma xenograft model

Jorge G. Gomez-Gutierrez, Michael E. Egger, Hongying Hao, Heshan Sam Zhou and Kelly M. McMasters
Pages 1195 - 1204
http://dx.doi.org/10.4161/cbt.21349
Abstract | Full Text | PDF

Melanoma is generally resistant to chemotherapy, which may be related to defects in death receptor signaling and to defects in induction of apoptosis. Forkhead family transcription factors induce the expression of death receptor ligands such as Fas ligand (Fas-L) resulting in apoptosis. We therefore investigated whether a triple mutant form of forkhead transcription factor FKHRL1 (FKHRL1/TM) can enhance Fas-L mediated-apoptosis in melanoma cells.

Two melanoma cells A2058 or DM6 were tested for their sensitivity to agonistic anti-Fas antibody (CH-11); adenovirus expressing FKHRL1/TM (Ad-FKHRL1/TM) was assessed for its capability to induce activation of the caspase pathway; the role of Fas-L in the Ad-FKHRL1/TM mediated-cell death was also assessed in vitro. Ad-FKHRL1/TM antitumor activity in vivo was also evaluated in a mouse melanoma xenograft model. We found that DM6 melanoma cells were more resistant to Fas/Fas-L-mediated apoptosis induced by agonistic anti-Fas antibody than A2058 melanoma cells. Ectopic expression of FKHRL1/TM in melanoma cells upregulated Fas-L expression, decreased procaspase-8 levels, and significantly increased Fas/FasL-mediated cell death in both cells lines; this induced cell death was partially blocked by a Fas/Fas-L antagonist. Importantly, Ad-FKHRL1/TM treatment of subcutaneous melanoma xenografts in mice resulted in approximately 70% decrease in tumor size compared with controls. These data indicate that overexpression of FKHRL1/TM can induce the Fas-L pathway in melanoma cells. Ad-FKHRL1/TM therefore might represent a promising vector for melanoma treatment.

Cancer cell spheroids as a model to evaluate chemotherapy protocols

Federico Perche and Vladimir P. Torchilin
Pages 1205 - 1213
http://dx.doi.org/10.4161/cbt.21353
Abstract | Full Text | PDF

To determine whether the spheroid culture can be used to evaluate drug efficacy, we have evaluated the toxicity of free or carrier-associated doxorubicin as a single drug or in combination with other antineoplastic agents using the spheroid cultures of drug-resistant cancer cells. Paclitaxel, cisplatin, dexamethasone, mitoxantrone, sclareol or methotrexate were used in combination with doxorubicin. The effect of the treatment protocols on free, micellar and liposomal doxorubicin accumulation in spheroids and on resulting toxicity was evaluated by fluorescence and lactate dehydrogenase release, respectively. Enhanced doxorubicin accumulation and toxicity were observed after spheroid pretreatment with mitoxantrone or paclitaxel. Effects of the drug combination with doxorubicin were sequence dependent, use of doxorubicin as the first drug being the least inducer of toxicity. Finally, spheroids were recognized by a cancer cell-specific antibody. Our results suggest the usefulness of spheroids to evaluate chemotherapy combinations.

Validation of Polo-like kinase 1 as a therapeutic target in pancreatic cancer cells

Chao Zhang, Xiaodong Sun, Yuan Ren, Yunbo Lou, Jun Zhou, Min Liu and Dengwen Li
Pages 1214 - 1220
http://dx.doi.org/10.4161/cbt.21412
Abstract | Full Text | PDF

Polo-like kinase 1 (PLK1) is a serine/threonine protein kinase and plays a critical role in mitosis. PLK1 has also been regarded as a valuable target for cancer treatment, and several PLK1 inhibitors are currently undergoing clinical investigations. In this study, our data show that the expression level of PLK1 is upregulated in human pancreatic cancer cells. Molecular modeling studies indicate that DMTC inhibits PLK1 activity through competitive displacement of ATP from its binding pocket. Our data further show that DMTC suppresses the proliferation of pancreatic cancer cells and induces the formation of multinucleated cells, ultimately resulting in apoptosis. In addition, combination index analysis demonstrates that DMTC acts synergistically with the chemotherapeutic drug gemcitabine in inhibiting the proliferation of pancreatic cancer cells. These results thus suggest a potential of using PLK1 inhibitors for the treatment of pancreatic cancer.

Inhibition of lung cancer cells growth, motility and induction of apoptosis by Klotho, a novel secreted Wnt antagonist, in a dose-dependent manner

Bo Chen, Xiaoli Ma, Shifeng Liu, Weihong Zhao and Jianqing Wu
Pages 1221 - 1228
http://dx.doi.org/10.4161/cbt.21420
Abstract | Full Text | PDF

Klotho (KL) is a transmembrane protein that can be shed, and act as a circulating hormone and modulate several signaling pathways. There also exists a splice variant of Klotho mRNA, which encodes a putative secreted protein (Klotho-S, KL-S) in both human and mouse. The potential anti-senescence gene Klotho has been recently found to participate in the progression of several different human cancers. In the current study, we undertook to study the expression and activity of Klotho in lung cancer cell line A549. Klotho expression was studied by using RT-PCR and western blotting. Effects of Klotho on cell growth and motility were assessed using MTT and scratch motility assay, and the apoptosis was assessed by TUNEL. Wnt signaling pathway activity was measured by western blotting. We established that the Klotho was endogenous expressed in A549 cells, but the expression level is lower compared with normal lung tissues. The overexpression of KL or KL-S could inhibit the cell proliferation, motility, and induce apoptosis in a dose-dependent manner. Also, we report KL could inhibit activation of Wnt -TCF/β-catenin signaling pathway, and it is involved in KL-induced growth inhibition. These studies indicate Klotho works as a potential tumor suppressor in lung cancer, and suggest that the Klotho tumor suppressive activities could be mediated through its KL-S isoform. These results suggest the use of Klotho or KL-S as potential strategy for the development of novel therapeutic interventions for lung cancers.