Different mRNA expression profile during tumor progression in a well-differentiated liposarcoma--A microdissection approach

An Evaluation of the Stemness, Paracrine, and Tumorigenic Characteristics of Highly Expanded, Minimally Passaged Adipose-Derived Stem Cells

The use of adipose-derived stem cells (ADSC) in regenerative medicine is rising due to their plasticity, capacity of differentiation and paracrine and trophic effects. Despite the large number of cells obtained from adipose tissue, it is usually not enough for therapeutic purposes for many diseases or cosmetic procedures. Thus, there is the need for culturing and expanding cells in-vitro for several weeks remain. Our aim is to investigate if long- term proliferation with minimal passaging will affect the stemness, paracrine secretions and carcinogenesis markers of ADSC. The immunophenotypic properties and aldehyde dehydrogenase (ALDH) activity of the initial stromal vascular fraction (SVF) and serially passaged ADSC were observed by flow cytometry. In parallel, the telomerase activity and the relative expression of oncogenes and tumor suppressor genes were assessed by q-PCR. We also assessed the cytokine secretion profile of passaged ADSC by an ELISA. The expanded ADSC retain their morphological and phenotypical characteristics. These cells maintained in culture for up to 12 weeks until P4, possessed stable telomerase and ALDH activity, without having a TP53 mutation. Furthermore, the relative expression levels of TP53, RB, and MDM2 were not affected while the relative expression of c-Myc decreased significantly. Finally, the levels of the secretions of PGE₂, STC1, and TIMP2 were not affected but the levels of IL-6, VEGF, and TIMP 1 significantly decreased at P2. Our results suggest that the expansion of passaged ADSC does not affect the differentiation capacity of stem cells and does not confer a cancerous state or capacity in vitro to the cells.

Immunohistochemical Detection of hTERT Protein in Soft Tissue Sarcomas

Human telomerase reverse transcriptase (hTERT) is a telomerase catalytic subunit that regulates telomerase activity. Telomerase is expressed in many human cancers and cell lines and is thought to contribute to their immortality. Little is known about the expression of telomerase in non-epithelial tumors. The objective of this study was to evaluate hTERT expression in a wide range of soft tissue sarcomas. A total of 154 cases of different types of soft tissue sarcoma (54 low-grade, 40 intermediate-grade, and 60 high-grade cases) were evaluated for hTERT expression using immunohistochemistry on tissue microarrays. hTERT immunoexpression was detected in 59% of cases; it was observed in 46%, 58%, and 72% of low-grade, intermediate-grade, and high-grade sarcoma cases, respectively. The intensity of staining positively correlated with the grade of the sarcomas: diffuse strong positive nuclear staining was identified in 6, 8, and 30 cases of low-grade, intermediate-grade, and high-grade sarcomas, respectively. These results suggest that telomerase expression is more often detected in highly malignant tumors than in low-grade sarcomas and thus may be a critical mechanism in tumor progression.

Function of HSP90 and p23 in the telomerase complex of thyroid tumors

Recently, studies on endocrine tumors revealed a potential role of telomerase in the dedifferentiation and/or malignant transition of these tumors. Telomerase is a ribonucleoprotein complex that includes the telomerase RNA component (hTR), the telomerase-associated protein (TP1), and the telomerase catalytic subunit (hTERT). Previously, the chaperones p23 and HSP90 have been described as additional telomerase regulators. To test whether the interactions of these genes are reflected in the dedifferentiation of thyroid tumors, we determined their mRNA and/or protein expression in 30 normal (tumor-free) thyroid tissues (NT), 35 follicular adenomas (FAD), 42 papillary carcinomas (PTC), 38 follicular carcinomas (FTC), 25 poorly differentiated carcinomas (PDTC), and 34 undifferentiated carcinomas (UTC). We then compared the results with telomerase activity. RT-PCR analysis revealed that TP1 was ubiquitously expressed. hTR was found in 50-94% of malignant tumors, in contrast to 7% of NT and 26% of FAD. hTERT was clearly associated with aggressive biological behavior. Ninety-two to 100% of the malignant tumors were positive for hTERT protein, whereas NT and FAD were negative in 100% and 94%, respectively. HSP90 mRNA and protein showed a close relationship to hTERT. p23 protein was negative in NT and positive in 3% of FAD, 39% of FTC, 40% of PTC, 44% of PDTC and 47% of UTC. High telomerase activity was measurable in hTERT and HSP90-positive tissues only. Our data show that the common expression of hTERT and HSP90 regulates telomerase activity in thyroid carcinomas. Chaperone p23 is involved in the telomeric complex to a lesser extent, but its expression is stronger in carcinomas than in non-malignant thyroid tissues. The expression profile of telomerase components represents an additional prognostic marker that may identify more aggressive thyroid tumors.