Telomerase activity correlates with growth of transplantable osteosarcomas in rats treated with cis-diammine dichloroplatinum or the angiogenesis inhibitor AGM-1470

Anti(angiogenic) food components: can be a major source of bias in the investigation of angiogenesis inhibitors

Background

Natural and diet-derived angiogenesis inhibitors/promotors are widely found in diets. These compounds can in several ways impact the results of oncological research of angiogenesis inhibitors.

Methods

We very briefly overview some of the most important examples to show how these compounds can create a bias in current research of cancer. Implications of this expert opinion cover similar angiogenesis-related diseases.

Results

Significant intra-individual differences in terms of dietary intake and differential effect of food processing techniques result in differential bioactivity and bioavailability of these compounds. There are only a handful of validated dietary questionnaire to quantify natural angiogenesis inhibitors/promotors. A corollary consequence is that participants in non-randomized clinical trials will have different baseline levels of serum/plasma/tissue/organ diet-derived angiogenesis inhibitors/promotors. This will lead to creation of clinical uncertainty and a hidden bias and consequently creation of translational efficiency bias, sampling efficiency, and waste of resources. We call for developing and validating a semi-quantitative food frequency questionnaire (FFQ) to gather data on these agents, specifically designed for oncological research because there is a clear gap in the literature of oncology.

Conclusions

This might facilitate the discovery of better prognostic, diagnostic, preventive measures, and therapeutic agents for the management of different cancers. Implications of this paper cover similar settings like ophthalmologic research.

Characterization of tree shrew telomeres and telomerase

The use of tree shrews as experimental animals for biomedical research is a new practice. Several recent studies suggest that tree shrews are suitable for studying cancers, including breast cancer, glioblastoma, lung cancer, and hepatocellular carcinoma. However, the telomeres and the telomerase of tree shrews have not been studied to date. Here, we characterize telomeres and telomerase in tree shrews. The telomere length of tree shrews is approximately 23 kb, which is longer than that of primates and shorter than that of mice, and it is extended in breast tumor tissues according to Southern blot and flow-fluorescence in situ hybridization analyses. Tree shrew spleen, bone marrow, testis, ovary, and uterus show high telomerase activities, which are increased in breast tumor tissues by telomeric repeat amplification protocol assays. The telomere length becomes shorter, and telomerase activity decreases with age. The tree shrew TERT and TERC are more highly similar to primates than to rodents. These findings lay a solid foundation for using tree shrews to study aging and cancers.

Content Determination of Active Component in Huangqi Yinyanghuo Group and Its Effects on hTERT and Bcl-2 Protein in Osteosarcoma

To screen the optimal extraction process and content determination of active component of Huangqi Yinyanghuo group (HYG) and to study the effects of HYG on human telomerase reverse transcriptase (hTERT) and Bcl-2 protein in osteosarcoma (HOS) cells, providing the theoretical basis for clinical application of HYG in treatment of osteosarcoma, orthogonal design table L9(4(3)) was used to design the extraction process of HYG, and icariin was taken as the investigation index to optimize the extraction process of HYG. 0.125, 0.25, 0.5, 1, 2, 4, and 8 μmol/L HYG were taken to act separately on logarithmic growth phase osteosarcoma HOS cells, CCK-8 assay was used to determine cell viability, and immunohistochemical SP assay was used to determine the expression of hTERT and Bcl-2 protein. Apoptosis rate was positively correlated with the dose of HYG, and the expressions of hTERT and Bcl-2 protein were significantly decreased with the prolonged duration of action. Under the effect of HYG, dose was negatively correlated with osteosarcoma cell survival fraction; osteosarcoma cell survival fraction was positively correlated with hTERT and Bcl-2 protein; duration of action was negatively correlated with hTERT and Bcl-2 protein; and hTERT and Bcl-2 protein were in a synchronous relationship.

Telomeres and telomerase biology in vertebrates: progress towards a non-human model for replicative senescence and ageing

Studies on telomere and telomerase biology are fundamental to the understanding of human ageing and age-related diseases such as cancer. However, human studies of whole body ageing are hampered by the lack of suitable fully reflective animal model systems, the wild-type mouse model being unsuitable due to differences in telomere biology. Here we summarise recent data on the biology of telomeres, telomerase, and the tumour suppressor protein p53 in various animals, and examine their possible roles in replicative senescence, ageing, and tumourigenesis. The advantages and disadvantages of various animals as model systems for whole body ageing in humans are discussed.

Telomerase activity is not a key determinant of sensitivity to standard cytotoxic drugs in human esophageal carcinoma cell lines

The aim of the present study was to investigate if basal telomerase activity levels may predict sensitivity to cytotoxic drugs in a panel of human esophageal carcinoma cell lines. The TRAPeze telomerase detection assay was used to investigate telomerase activity in the cell lines. Cytotoxic drug sensitivity for 20 standard cytotoxic agents was assessed using the fluorometric microculture cytotoxicity assay (FMCA). Telomerase activity was detected in all cell lines with a broad range of activity levels. Drug sensitivity also varied considerably between the cell lines. Except for a P value towards a correlation between mitoxantrone and telomerase activity (P=0.054), no statistically significant correlation was found between telomerase activity levels and sensitivity to investigated drugs, including key drugs such as cisplatin (P=0.9), 5-fluorouracil (P=0.8) and doxorubicin (P=0.54). We therefore conclude that basal telomerase activity level is not a key determinant of sensitivity to standard cytotoxic drugs in esophageal carcinoma cell lines.

Tumour angiogenesis: a novel therapeutic target in patients with malignant disease

Angiogenesis refers to the formation of new blood vessels from an existing vasculature and is recognised as a necessary requirement for most tumours to grow beyond 1-2 mm in diameter. Factors established as playing a role in angiogenesis may be divided into two principal groups: (a) those that stimulate endothelial cell proliferation and/or elongation, migration and vascular morphogenesis including vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), platelet derived endothelial cell growth factor (PD-ECGF) and the tie and tek receptors, and (b) proteases and their receptors involved in the breakdown of basement membranes and the extracellular matrix (ECM) including the matrix metalloproteinases (MMPs), cathepsins and those involved in the plasmin cascade. Angiogenesis has been identified as a potential target for development of anticancer agents. The discovery of a range of naturally-occurring factors which negatively regulate angiogenesis, including the thrombospondins, angiostatin and endostatin, and the tissue inhibitors of MMPs (TIMPs), has given added impetus to this approach. Synthetic anti-angiogenic compounds have been developed, including TNP-470, carboxyamidotriazole, VEGF-tyrosine kinase inhibitors and MMP inhibitors (MMPI) which, like the naturally-occurring anti-angiogenic factors, inhibit angiogenesis in vitro and in vivo, and tumour development, growth and metastasis in vivo. Anti-angiogenic agents also enhance the antitumour activity of many conventional cytotoxic chemotherapeutic agents. Such combinations may have a particular role as adjuvant therapies following surgical resection of primary tumours. Unlike tumour cells, tumour associated endothelial cells do not develop resistance to anti-angiogenic agents. Furthermore, anti-angiogenic agents are generally cytostatic rather than cytotoxic. As such, these agents are, in general, likely to be administered over long periods of time. Therefore, as well as having proven antitumour efficacy, an anti-angiogenic compound will need to be well-tolerated if it is to become established in the clinical management of patients with malignant disease.

Telomerase activity in juxtacortical and conventional high-grade osteosarcomas: correlation with grade, proliferative activity and clinical response to chemotherapy

Seven samples from seven patients with juxtacortical osteosarcomas, and 27 samples from 19 patients with conventional high-grade osteosarcomas were investigated for a possible correlation between telomerase activity and clinicopathological features such as age, sex, and response to chemotherapy. Of seven juxtacortical osteosarcomas, telomerase activity was weakly positive in three parosteal osteosarcomas, and highly positive in one parosteal osteosarcoma. In contrast, of 27 conventional high-grade osteosarcomas, telomerase activity was weakly positive in eight tumors and highly positive in three. Of all samples, 44.1% of the osteosarcomas showed telomerase activity (57.1% of juxtacortical and 40.7% of conventional osteosarcomas). The majority of poor responders to chemotherapy showed no telomerase activity (nine of 11), whereas five of seven good responders showed strong or weak telomerase activity. There was a significant correlation between telomerase activity and the response to chemotherapy (P<0.05). Telomerase activity was not correlated with MIB-1 proliferation index, age at the time of surgery, or sex. These findings suggest that telomerase activation occurs early in the oncogenesis of osteoblastic tumors without having an effect on the progression of these tumors. In malignant osteoblastic tumors, the biological significance of telomerase activation is different from that described for most epithelial cancers.

Telomerase activity in esophageal squamous cell carcinoma: down-regulation by chemotherapeutic agent

BACKGROUND AND OBJECTIVES

Telomerase has been suggested as being necessary for continued cell growth and progression of cancer. Esophageal cancer and matched normal esophageal tissue from 54 patients were analyzed for telomerase activity, human telomerase reverse transcriptase (hTERT) mRNA expression, and their correlation with clinicopathological factors.

METHODS

Telomeric repeat amplification protocol was used for detection of telomerase activity and real time quantitative RT-PCR was used for hTERT mRNA. An esophageal carcinoma cell line was used to study the effect of chemotherapeutic agent on telomerase.

RESULTS

Telomerase activity was detectable in 79.6% of the tumor and 59.3% of the normal esophageal tissue. The level of telomerase activity in the tumor was significantly higher than that in the normal tissue. A significantly higher telomerase activity was observed in tumors with extensive blood vessel invasion. A significantly lower telomerase activity was observed in tumors that showed good response to preoperative chemotherapy than those with poor response. TE-9 cells exposed to 5-FU showed a diminished telomerase activity preceded by a time-dependent decrease in the mRNA expression of hTERT.

CONCLUSIONS

Telomerase activity was high in esophageal cancer tissue and showed positive correlation with blood vessel invasion. Chemotherapeutic agents may down-regulate telomerase activity.

Hepatic angiomyolipoma in a 26-year-old Caucasian woman with a history of tibial osteosarcoma

We report on a 26-year-old Caucasian woman who was referred to the Department of Surgery complaining of general malaise, feeling of fullness with occasional vomiting and intermittent jaundice. The patient had previously suffered from tibial osteosarcoma of the left leg which was resected 13 years ago and subsequently treated with radiation and chemotherapy. During clinical investigations a 12 x 12 x 6.5 cm large mass was found in the left lobe of the liver. This was resected, and subsequently shown to be a sporadic hepatic angiomyolipoma. In order to investigate a possible link between the two tumours, we investigated mutations in the p53-gene, loss of heterozygosity (LOH) at p53, Rb and p16, c-Myc expression, and the telomerase activity of the angiomyolipoma and the osteosarcoma. Whilst the tibial osteosarcoma showed LOH at p16, no genetic alterations or increased telomerase activity were found in the angiomyolipoma. The occurrence of both these tumours in this patient is therefore probably a coincidence.

Telomerase activity in benign bone tumors and tumor-like lesions

To assess the role and status of telomerase activity in benign bone tumors and tumor-like lesions, we performed telomerase assays in four giant cell tumors of bone, four fibrous dysplasias, three osteochondromas, three aneurysmal bone cysts, two osteoblastomas, one juvenile bone cyst and one myositis ossificans. A very sensitive non-radioactive TRAP assay was applied. Low level activity was detected in 7 of 18 tumor samples (38.9%), and high level activity was not detected in any of the cases. Telomerase activity was observed in all patients with osteochondromas, in two of the three aneurysmal bone cysts, in one of the four giant cell tumors of bone and in one of the four fibrous dysplasias, but not in osteoblastomas, juvenile bone cyst and myositis ossificans. Although the origin of this enzyme is still unclear, it might play a role in precancerous immortalization of benign bone tumors. Other possible reasons explaining the occurrence of telomerase activity, such as migrating lymphocytes or contamination of immortalized non-tumor cells, should not be ruled out. Telomerase activity, however, does exist in those samples having no malignant phenotype, for which reason telomerase assays are not always useful for the clinical and diagnostic approach in benign bone tumors. Determination of the telomerase status in benign lesions may contribute to a better understanding of the regulation mechanism of telomerase activity during progression of bone tumors.

A selective cyclooxygenase-2 inhibitor suppresses tumor growth in nude mouse xenografted with human head and neck squamous carcinoma cells

The anti-tumor effect of a selective cyclooxygenase (COX)-2 inhibitor, JTE-522, was examined with the human head and neck squamous cell carcinoma cell line KB. KB cells do not produce prostaglandin (PG)-E2. In vitro, JTE-522 induced an increase of G1 phase-arrested cells, suppression of platelet-derived growth factor (PDGF) production and inhibition of telomerase activity. No cytotoxic effect was detected. In vivo, the growth of the tumor xenografted into nude mice was significantly suppressed by JTE-522. Suppression of angiogenesis at the periphery of the tumor, increase of G1-arrested cells and suppression of telomerase activity were observed, together with an increase of apoptotic cell death in the tumor. Immunological enhancement did not play a role. We concluded that the anti-tumor effect of JTE-522 was caused by anti-angiogenesis action, cell cycle arrest and inhibition of telomerase activity of the tumor cells. These combined effects might induce apoptosis.

Indomethacin suppresses the growth of colon 26, Meth-A and FM3A tumors in mice by reducing the prostaglandin E2 content and telomerase activity in tumor tissues

The antitumor effect of indomethacin on Colon 26, Meth-A and FM3A tumors was investigated in mice. The prostaglandin E2 content in tumor tissues was assayed to find out if indomethacin acts on tumors, and the telomerase activity in tumors and somatic tissues (testis, liver, spleen and colon) was also monitored during indomethacin treatment. Growth of Colon 26, Meth-A and FM3A tumors was significantly (P < 0.001-0.05) suppressed by indomethacin compared to the untreated controls. The prostaglandin E2 content in the three tumors was markedly (P < 0.001) reduced by indomethacin. Telomerase activity in Colon 26 and FM3A tumors was significantly (P < 0.001) lower than that of untreated tumors (80% and 45% decrease versus the controls, respectively), and the activity in Meth-A tumor was slightly decreased (10% decrease versus the control) by indomethacin. Telomerase activity in the somatic tissues was not significantly affected by indomethacin. In summary, this study shows the effectiveness of indomethacin as an antitumor agent against three types of tumors, and suggests that indomethacin affects telomerase activity in tumors in vivo.