Cancer stem cells as targets for cancer therapy: selected cancers as examples.

It is becoming increasingly evident that cancer constitutes a group of diseases involving altered stem-cell maturation/differentiation and the disturbance of regenerative processes. The observed malignant transformation is merely a symptom of normal differentiation processes gone astray rather than the primary event. This review focuses on the role of cancer stem cells (CSCs) in three common but also relatively under-investigated cancers: head and neck, ovarian, and testicular cancer. For didactic purpose, the physiology of stem cells is first introduced using hematopoietic and mesenchymal stem cells as examples. This is followed by a discussion of the (possible) role of CSCs in head and neck, ovarian, and testicular cancer. Aside from basic information about the pathophysiology of these cancers, current research results focused on the discovery of molecular markers specific to these cancers are also discussed. The last part of the review is largely dedicated to signaling pathways active within various normal and CSC types (e.g. Nanog, Nestin, Notch1, Notch2, Oct3 and 4, Wnt). Different elements of these pathways are also discussed in the context of therapeutic opportunities for the development of targeted therapies aimed at CSCs. Finally, alternative targeted anticancer therapies arising from recently identified molecules with cancer-(semi-)selective capabilities (e.g. apoptin, Brevinin-2R) are considered.

Expression of neutral endopeptidase (NEP/CD10) on pancreatic tumor cell lines, pancreatitis and pancreatic tumor tissues.

Neutral endopeptidase (NEP/CD10) is a cell surface zinc metalloprotease cleaving peptide bounds on the amino terminus of hydrophobic amino acids and inactivating multiple physiologically active peptides. Loss or decrease in NEP/CD10 expression have been reported in many types of malignancies, but the role of NEP/CD10 in pancreatic carcinoma has not yet been identified. Using real-time RT-PCR, flow cytometry as well as immunohistochemistry, NEP/CD10 expression was quantified in both pancreatic carcinoma cell lines and in tumor specimens obtained from patients with primary pancreatic carcinomas. Three out of 8 pancreatic carcinoma cell lines exhibit heterogeneous NEP/CD10 expression levels: PATU-8988T expressed the highest NEP/CD10 levels, whereas HUP-T4 and HUP-T3 cells showed a moderate to low NEP/CD10 expression. NEP/CD10 immunoreactivity was found in 6 of 24 pancreatic ductal adenocarcinomas, but also in 3 of 6 tissues of patients with chronic pancreatitis. NEP/CD10 expression in pancreatic tumor lesions and cell lines was not associated with tumor grading and staging. Treatment of PATU-8988T cells with the histone deacetylase inhibitors sodium butyrate and valproic acid induced an increase of NEP/CD10 expression. This was accompanied by a reduced cell proliferation rate of PATU-8988T cells, which was increased by the addition of the enzyme activity inhibitors phosphoramidon and thiorphan. Thus, NEP/CD10 is differentially expressed in pancreatic tumors and might be involved in the proliferative activity of pancreatic cancer cells. However, further studies are needed to provide more detailed information of the role of NEP/CD10 under physiological and pathophysiological conditions of the pancreas.

Fetal microchimerism in Hashimoto's thyroiditis: a quantitative approach.

OBJECTIVE: Fetal microchimerism (MCH) has been implicated in the etiology of autoimmune diseases such as autoimmune thyroiditis. The goal of the study was to reliably estimate the number of fetal engrafted cells and to further investigate factors influencing the development of MCH. METHODS: Quantitative real-time PCR amplification using Y-chromosome specific (DYS14) and autosomal (beta-globin) loci was performed on thyroid gland specimens. Furthermore, we compared the distribution of ABO and rhesus systems in mothers with and without blood MCH in relation to the blood groups of the children. RESULTS: MCH was detected in eight of 21 Hashimoto patients in a frequency range of 15 to 4900 male cells per 100,000 total cells (median 97 cells), but in none of 17 healthy thyroid glands. In a third group, consisting of 18 nodular goiters, only one sample was positive (182 male cells/100,000 total cells). No woman who had not had a prior pregnancy with a male fetus showed MCH. Mothers both with and without MCH showed the same rate of mother/child incompatibilities for the ABO and rhesus systems. CONCLUSIONS: The percentage of microchimeric cells varies to a great extent in Hashimoto's thyroiditis, and this phenomenon can occur in nodular goiter in rare instances, but it appears to be absent from normal thyroid glands. Nevertheless, the biological significance of MCH remains unclear. Moreover, we have concluded that the tested blood group systems (as opposed to their role in graft vs host disease after transplantations) have no effect on fetal MCH.

Human medullary thyroid carcinoma: a source and potential target for relaxin-like hormones.

We investigated the expression of H1, H2 relaxin and INSL-3, mRNA and protein, and LGR7 and LGR8 transcripts in human C-cell hyperplasia, primary medullary thyroid carcinoma (MTC) tissues, MTC metastases, and the human MTC-TT and mouse MTC-M cell lines. Relaxin-like peptide hormones were detected in C-cell hyperplasia and in MTC tissues, but were absent in human normal parafollicular C-cells of benign goiter tissues. In contrast to calcitonin, mRNA, and immunoreactive protein, no differences in the expression of relaxin and INSL3 were observed in MTC tissues of different pTNM classification or between primary and metastatic MTC tissues studied. All MTC tissues constitutively expressed LGR7 and LGR8 transcripts. Thus, relaxin-like hormones appear to be present early during C-cell hyperplasia and potentially functional relaxin/INSL3 ligand-receptor systems are present in human MTC tissues and in MTC cell lines.

Expression of the epidermal growth factor seven-transmembrane member CD97 correlates with grading and staging in human oral squamous cell carcinomas.

INTRODUCTION: The oral squamous cell carcinoma (OSCC) is the sixth most common malignant tumor worldwide. No significant better progress has been made in the treatment of OSCCs during the last decades. The heterodimeric CD97 protein is a epidermal growth factor seven-transmembrane family member and was identified as a dedifferentiation marker in thyroid carcinomas. Nothing is known about CD97 in OSCCs. MATERIAL AND METHODS: Employing UV-laser microdissection, CD97 and its ligand CD55 were investigated in normal oral mucosa and OSCCs (n = 78) by multiplex reverse transcription-PCR. Frozen sections were investigated by immunohistochemistry. The effects of retinoic acid and sodium butyrate on the CD97/CD55 expression in OSCC cell lines were determined by quantitative PCR, immunocytochemistry, and flow cytometry. RESULTS: Weak CD97 transcripts were expressed in normal mucosa and normal basal epithelial cells revealed specific CD97 immunostaining. Strong CD97 transcripts were detected in pT(3)/T(4) and G3/G4 OSCC tissues, whereas pT(1)/T(2) and G1/G2 carcinomas revealed weak CD97 transcript levels. A weak CD97 immunostaining was observed in pT(1)/T(2) and G1/G2 tumors. By contrast, intensive CD97 immunostaining was detected in pT(3)/T(4) OSCCs and G3/G4 lesions. CD55 gene expression was low in normal mucosa. All OSCCs, irrespective of stage and grading, displayed strong CD55 immunostaining. Sodium butyrate and retinoic acid inhibited CD97 mRNA and protein in OSCC cell lines. Interestingly, CD55 was up-regulated by both substances. CONCLUSION: We identified CD97 as a novel marker of dedifferentiated OSCC. Interaction of CD97 and CD55 may facilitate adhesion of OSCC cells to surrounding surfaces that would result in metastases and bad prognosis.

CD82, and CD63 in thyroid cancer.

CD82 (KAI1) and CD63 (ME491) are highly glycosylated proteins which belong to the transmembrane 4 superfamily (TM4SF). CD82 has been implicated as a possible prostate cancer metastasis suppressor gene, whereas CD63 is involved in the progression of human melanoma cancer. Down-regulation of both CD82 and CD63 expression has been associated with the metastatic potential of several solid tumors. Currently, information is lacking on the role of CD82 and CD63 during thyroid carcinogenesis. The aim of this study was to determine whether the expression of CD82 and CD63 is a useful prognostic indicator in patients with thyroid carcinoma. The expression of CD82 and CD63 was analysed by reverse transcriptase-PCR (RT-PCR) and immunohistochemistry in benign goiter (n=12) and 75 primary thyroid carcinoma tissue specimens (PTC: 33, FTC: 24, UTC: 18) out of which 36 were non-metastasized primary tumors and 39 were metastasized tumors (regional lymph node and/or distant metastases). All of the benign goiter tissues showed CD82 expression. By contrast, a significant decrease in CD82 mRNA and protein levels was detected in carcinoma tissues as compared to benign goiter tissues (p<0.001). A similar down-regulation was observed in metastasized tumor tissues when compared with non-metastasized tumors (all p<0.05). CD82 expression was correlated with pTNM status of differentiated and undifferentiated thyroid tumor and the pathologic stage of differentiated thyroid tumor. In contrast to CD82, CD63 mRNA and protein expression was unchanged in all thyroid carcinomas. Benign goiter tissues showed weak expression of CD63. There were no significant correlation between CD63 mRNA/protein expression and any clinical/pathological parameters. Our results support the hypothesis that down-regulation of CD82 expression may reflect an increased in vivo metastatic potential of thyroid cancer cells. CD82 may serve as a prognostic marker of metastasis in thyroid cancer. Constitutive expression of CD63 may indicate that this factor does not play a direct role in thyroid carcinogenesis.

Expression of CD97 and CD55 in human medullary thyroid carcinomas.

The heterodimeric CD97 protein is a member of the EGF-TM7 family of class II seven-transmembrane (7TM) receptors of 75-90 kDa and structurally related to the secretin receptor family. CD97 is expressed on leucocytes, lymphocytes and in cells of the hematopoietic system. The precise role for CD97 is still unknown. The ubiquitously expressed CD55 (also known as decay accelerating factor, DAF) protects host cells from complement attack. In addition, CD55 is a bacterial/viral receptor and was identified as a ligand for CD97. Employing computer aided UV-laser microdissection CD97 and CD55 were investigated in C-cells of non-neoplastic thyroid specimens (n=3) and in medullary thyroid carcinomas (n=54) by multiplex RT-PCR. Frozen sections of all tissues were investigated by immunohistochemistry. All non-malignant thyroid specimens expressed CD97 mRNA weakly and were devoid of immunoreactive CD97 protein. Transcripts for CD97 were detected in all 54 MTC tissue specimens and CD97 gene activity directly correlated with the histopathological stage of the MTC. CD97 transcriptional activity was high in advanced stages of MTC such as pT3/4. pT1/2 tumors with exclusive intrathyroidal growth revealed weak CD97 expression. CD55 gene expression was significantly lower in normal C-cells than in tumor tissues and all MTC displayed strong and specific CD55 immunostaining. We did not observe a correlation between the expression of CD55 mRNA or protein, respectively, and pTNM classification. In summary, in the present study we have identified CD97 as a novel marker expressed in dedifferentiated neoplastic human thyroid C-cells. CD97 and CD55 may facilitate adhesion of C-cell carcinoma to surrounding surfaces which would result in rapid tumor cell spread.