Generation of Human Antibodies Against a Specific Peptide: a Novel Strategy Based on Human Cells.

BACKGROUND/AIM: We developed a novel platform to produce fully human antibodies that could be used as tools in cancer research. This study was based on maturation of B-cells into plasma cells and the subsequent secretion of fully human antibodies against a 9-mer peptide. MATERIALS AND METHODS: A peptide was introduced to dendritic cells, followed by co-cultivation with cluster of differentiation 4 (CD4+) cells from healthy donors and CD19(+) cells from patients with cancer. In order to detect plasma cells, we used microscopy, flow cytometry, enzyme-linked immunosorbent assays (ELISAs), and western blotting. RESULTS: Oval-shaped cells with eccentric nuclei were found which expressed high levels of CD27 (up to 73%) and CD138 (up to 31%). An antibody against the selected peptide was detected in the culture supernatants of all samples according to ELISA and western blot analyses. CONCLUSION: This platform successfully generated fully human antibodies against a specific epitope.

Identification of genes involved in breast cancer and breast cancer stem cells.

Breast cancer is the most frequent type of cancer in women. Great progress has been made in its treatment but relapse is common. One hypothesis to account for the high recurrence rates is the presence of cancer stem cells (CSCs), which have the ability to self-renew and differentiate into multiple malignant cell types. This study aimed to determine genes that are expressed in breast cancer and breast CSCs and to investigate their correlation with stemness. RNA was extracted from established breast cancer cell lines and from CSCs derived from five different breast cancer patients. DNA microarray analysis was performed and any upregulated genes were also studied in other cancer types, including colorectal and lung cancer. For genes that were expressed only in breast cancer, knockdown-based experiments were performed. Finally, the gene expression levels of stemness transcription factors were measured. The outcome of the analysis indicated a group of genes that were aberrantly expressed mainly in breast cancer cells with stemness properties. Knockdown experiments confirmed the impact of several of these on NANOG, OCT3/4, and SOX2 transcription factors. It seems that several genes that are not directly related with hormone metabolism and basic signal transduction pathways might have an important role in relapse and disease progression and, thus, can be targeted for new treatment approaches for breast cancer.

Involvement of retrotransposon L1 in stemness and cellular plasticity.

Epithelial-to-mesenchymal transition (EMT) as well as the reverse process, mesenchymal-to-epithelial transition (MET) is important during embryogenesis. EMT is also involved in cancer invasion and metastasis, and can generate cells with properties similar to those of stem cells. Retrotransposons can rearrange the genome by inserting DNA in new loci, thus inducing mutations. This study examines the gene expression of transcription factors involved in EMT and MET. In the second experimental panel, the gene expression of L1 retrotransposon was studied. L1-open reading frame (ORF) 2 mRNA was found to be expressed both in cancer and cancer stem cells, while L1-ORF1 mRNA was expressed only in cancer cells. The suppression of L1-ORF2 gene expression demonstrated that this retrotransposon might affect EMT in colon cancer stem cells. This study highlights that the EMT process seems to differ between cancer cells and cancer stem cells, and that transposable elements seem to be involved in the process, influencing cellular plasticity.

Potential role for the Metnase transposase fusion gene in colon cancer through the regulation of key genes.

The Metnase fusion gene consists of a SET histone methyltransferase domain and a transposase domain from Mariner transposase. This transposable element is involved in chromosome decatenation, enhances DNA repair, promotes foreign DNA integration, and assists topoisomerase II function. This study investigates the role of Metnase in colon cancer homeostasis and maintenance of the stemness phenotype in colon cancer stem cells (CSCs). Silencing of Metnase was performed in human cancer cell lines before and after treatment with cisplatin, and in colon CSCs. Subsequent changes in the expression of genes involved in repair mechanisms, DNA synthesis, topoisomerase II function, and metastasis as well stemness transcription factors were studied with RT-qPCR experiments. Cellular viability and apoptosis were evaluated by flow cytometry. The results suggest that Metnase influences the expression of many genes involved in the above processes. Furthermore, Metnase levels appear to impact upon expression of NANOG, OCT3/4, and SOX2. Suppression of Metnase also led to an increase in apoptosis. Therefore, Metnase may possess an important role in DNA repair, topoisomerase II function, and the maintenance of stemness during colon cancer development.

Comparison of the growth curves of cancer cells and cancer stem cells.

A fundamental problem in cancer research is identification of the cells responsible for tumor formation. The latest field of cancer research has revealed the existence and role of cancer stem cells (CSCs). These findings support the idea that malignancies originate from a small fraction of cancer cells that show self-renewal and multi- or pluripotency. Identification of this CSC population has important implications for the management of cancer patients, including diagnostic and predictive laboratory assays as well as novel therapeutic strategies that specifically target CSCs. In this study, we investigated the growth rates of CSC populations for comparison with cancer cell lines. To construct the growth curves, blood-derived CSCs were isolated from patients with breast, colon, or lung cancer and cultured in vitro. Quantitative real-time PCR was then performed to identify CSCs in the samples. We found that CSCs did not follow the common pattern of a typical growth curve of mammalian cells in contrast to the cancer cell lines. This observation of rapidly growing CSCs indicates their involvement in tumor formation.

Use of the comet assay technique for quick and reliable prediction of in vitro response to chemotherapeutics in breast and colon cancer.

BACKGROUND: Determination of response to chemotherapy is a major requirement of personalized medicine. Resistance, whether developed or native, critically affects a treatment's success. Single Cell Gel lectrophoresis - also known as a comet assay - is used to detect DNA damage at the level of individual eukaryotic cells. We assessed the use of comet assays in determining response to chemotherapeutic drugs that are widely used in breast and colon cancer. RESULTS: We treated human breast and colon cancer cell lines with melphalan, cisplatin, mechlorethamine or doxorubicin, as monotherapies. Drug activities varied even in the same cancer types, further demonstrating the heterogeneity of different cancer types. CONCLUSION: The comet assay technique can provide reliable and quick results with minimum requirements and is applicable to a wide variety of drugs.

Study of the interaction among Notch pathway receptors, correlation with stemness, as well as their interaction with CD44, dipeptidyl peptidase-IV, hepatocyte growth factor receptor and the SETMAR transferase, in colon cancer stem cells.

CONTEXT: The Notch signaling pathway is one of the most important pathways during normal development and implicated in self-renewal of adult stem cells and differentiation of progenitor cells. Abnormal expression of Notch receptors has been associated with many epithelial metaplastic and neoplastic lesions. OBJECTIVE-MATERIALS AND METHODS: In this particular study, it was determined the relative gene expression of Notch receptors after knockdown experiments in colon cancer stem cells (CSCs) and the gene expression changes in stemness transcription factors (Oct4, Sox2, Nanog), as well in dipeptidylpeptidase-4, CD44 antigen, Met proto-oncogene and in Metnase transposase. RESULTS: In control CSCs Notch-2 had the higher expression, followed by Notch-1, Notch-3. Notch-4 demonstrated the lower gene expression among the receptors. The suppression of Notch-1 led to increased expression of Oct4 and Sox2, but in decreased gene expression of cMET, Setmar and CD44. The CD26 expression remained unchanged. The knockdown of Notch-2 led to decreased expression of all transcription factors. Notch-3 down regulation caused increased Oct4 gene expression, but decreased levels for the rest of the genes. Finally, the suppression of Notch-4 had the same effect as in receptor Notch-3. DISCUSSION AND CONCLUSION: The above experimental data suggest the possible interaction between the four different receptors of Notch signaling pathway. The expression of CD26, cMET and N-methyltransferase Setmar was also changed. Finally, the stemness phenotype was changed in a different way each time, according to the receptor that was down regulated. All Notch receptors and particularly Notch-2 seem to play an important role in cancer stem cells.

Anvirzel™ in combination with cisplatin in breast, colon, lung, prostate, melanoma and pancreatic cancer cell lines.

BACKGROUND: Platinum derivatives are used widely for the treatment of many cancers. However, the toxicity that is observed makes imperative the need for new drugs, or new combinations. Anvirzel™ is an extract which has been demonstrated with experimental data that displays anticancer activity. The aim of the present study is to determine whether the combination of Cisplatin and Anvirzel™ has a synergistic effect against different types of cancer. MATERIALS AND METHODS: To measure the efficacy of treatment with Cisplatin and Anvirzel™, methyl-tetrazolium dye (MTT) chemosensitivity assays were used incorporating established human cancer cell lines. Measurements were performed in triplicates, three times, using different incubation times and different concentrations of the two formulations in combination or on their own. t-test was used for statistical analysis. RESULTS: In the majority of the cell lines tested, lower concentrations of Anvirzel™ induced a synergistic effect when combined with low concentrations of Cisplatin after an incubation period of 48 to 72 h. The combination of Anvirzel™/Cisplatin showed anti-proliferative effects against a wide range of tumours. CONCLUSION: The results showed that the combination of Anvirzel™ and Cisplatin is more effective than monotherapy, even when administered at low concentrations; thus, undesirable toxic effects can be avoided.

AP-1 Gene Expression Levels May Be Correlated with Changes in Gene Expression of Some Stemness Factors in Colon Carcinomas.

The AP-1 transcription factor is a heterodimer protein that regulates gene expression in response to a variety of extrinsic stimuli through signal transduction. It is involved in processes including differentiation, proliferation, and apoptosis. Among the genes it regulates are transcription factors that contribute to the stemness phenotype. Cancer stem cells have the ability to self-renew and initiate differentiation into heterogenic cancer cells, which may cause metastasis and relapses. In the present study, we evaluated the effect of AP-1 complexes, as well as the C-FOS and C-JUN genes, in relation to NANOG, OCT3/4, and SOX2 transcription factors. All assays were undertaken with colon cancer stem cells. Knockdown experiments with siRNA were performed for each individual gene as well as their combination. Changes in gene expression were calculated with quantitative polymerase chain reaction experiments, while the effect on cell cycle distribution and apoptosis was studied by flow cytometry. The results differed depending on the percentage of repression, as well as the gene that was suppressed. In all cases, the number of apoptotic cells was increased. These findings indicate that AP-1 may have a crucial role in the maintenance of cancer stem cells.

Cancer stem cells stemness transcription factors expression correlates with breast cancer disease stage.

Cancer stem cell-like cells (CSCs) are cancer cells that have the ability of self-renewal and differentiation into multiple malignant cell types (hierarchy). Thus, can cause relapses and metastasis. CSCs' phenotype is defined by special transcription factors such as Nanog, Oct3/4, Sox2, Nestin, and CD34. The present study aims to determine the change in gene expression of the above markers in correlation with the stage of the disease in breast cancer patients. Initially, whole blood samples from patients with breast cancer were collected, followed by the isolation and culture of circulating tumor cells (CTCs). This was followed by the quantification of CSCs from the above cultures. CSCs' molecular analysis was performed with qPCR, with the use of gene specific primers. At the same time of the analysis, the clinical assessments of the patients were requested from their physicians. The results indicated a linear relationship between the gene expression of stemness markers and the stage of the disease, as well as specific expression patterns by stage. It seems that these genes have an important role in the progression of the disease, thus they might be target for new treatment approaches.

Bacterial and fungal microflora in surgically removed lung cancer samples.

BACKGROUND: Clinical and experimental data suggest an association between the presence of bacterial and/or fungal infection and the development of different types of cancer, independently of chemotherapy-induced leukopenia. This has also been postulated for the development of lung cancer, however the prevalence and the exact species of the bacteria and fungi implicated, have not yet been described. AIM: To determine the presence of bacterial and fungal microflora in surgically extracted samples of patients with lung cancer. MATERIALS AND METHODS: In this single-center prospective, observational study, tissue samples were surgically extracted from 32 consecutive patients with lung cancer, and reverse-transcription polymerase chain reaction (RT-PCR) was used to identify the presence of bacteria and fungi strains. RESULTS: The analysis of the electrophoresis data pointed out diversity between the samples and the strains that were identified. Mycoplasma strains were identified in all samples. Strains that appeared more often were Staphylococcus epidermidis, Streptococcus mitis and Bacillus strains, followed in descending frequency by Chlamydia, Candida, Listeria, and Haemophilus influenza. In individual patients Legionella pneumophila and Candida tropicalis were detected. CONCLUSIONS: A diversity of pathogens could be identified in surgically extracted tissue samples of patients with lung cancer, with mycoplasma strains being present in all samples. These results point to an etiologic role for chronic infection in lung carcinogenesis. Confirmation of these observations and additional studies are needed to further characterize the etiologic role of inflammation in lung carcinogenesis.

Correlation between Cancer Stem Cells and Circulating Tumor Cells and Their Value.

BACKGROUND: The scientific community has proven the value of circulating tumor cells (CTCs) as a prognostic factor in the development of cancer and progress to metastases [1, 2, 3, 4]. Simultaneously, a new type of cancer stem cell-like (CSC-like) cells has also been established as a progenitor of metastases and relapses in cancer patients [5, 6]. The present research attempts to support the hypothesis that CTCs have all the cellular hallmarks of CSC-like cells which play a crucial role in cancer spreading. MATERIALS AND METHODS: TWO METHODS HAVE BEEN CHOSEN: a cellular-based and a molecular-based method. The first method is based on the fact that CSCs form microspheres in culture. In the second method, microspheres develop in the presence of specific markers that define the CSC phenotype [6]. RESULTS: In cellular-based assays, it has been shown that microspheres form in semi-suspension in a culture flask. In the second panel of the test, Nanog was chosen as a marker and the tested sample was positive when grown under specific conditions. CONCLUSION: Our analysis has demonstrated that in this particular case, CSCs-like cells are included in the vast majority of CTCs.