Circulating CD133(+)/ESA(+) cells in colorectal cancer patients.

BACKGROUND: Tumor initiating cells are a small subset of cancer cells responsible for tumor growth and recurrence. The status of tumor initiating cells was measured using the surface markers CD133 (prominin-1) and ESA (epithelial-specific antigen). The aims of this study were to investigate the significance of CD133(+)/ESA(+) cells in mesenteric venous blood (MVB) and tumor mass (TM) for overall survival (OS) and disease-free survival (DFS) in colorectal cancer (CRC) patients undergoing curative resection. MATERIALS AND METHODS: A total of 229 CRC patients undergoing curative resection were prospectively enrolled in the study. Using CD133 and ESA as surface markers, CD133(+)/ESA(+) cells were enumerated from MVB and TM using flow cytometry. RESULTS: We analyzed the presence of CD133(+)/ESA(+) cells in TM from 158 patients and found no correlation to patient DFS, OS, or clinical stage. In 135 patients, an analysis of CD133(+)/ESA(+) cells in MVB showed an inverse correlation with both DFS and OS (P = 0.014 and P = 0.008, respectively). It exhibited an increase-then-decrease pattern with the peak in stage II patients. A multivariate Cox analysis demonstrated that the status of CD133(+)/ESA(+) cells in MVB, but not the TM, was a significant prognostic factor for DFS and OS (P = 0.003 and P = 0.011, respectively). CONCLUSIONS: The status of CD133(+)/ESA(+) cells in MVB, but not in TM, could be a useful indicator for predicting tumor recurrence and a prognostic marker for CRC patients.

Isolation and characterization of adult mammary stem cells from breast cancer-adjacent tissues.

Normal adult mammary stem cells (AMSCs) are promising sources for breast reconstruction, particularly following the resection of breast tumors. However, carcinogenic events can potentially convert normal AMSCs to cancer stem cells, posing a safety concern for the use of AMSCs for clinical tissue regeneration. In the present study, AMSCs and autologous primary breast cancer cells were isolated and compared for their ability to differentiate, their gene expression profile, and their potential to form tumors in vivo. AMSCs were isolated from normal tissue surrounding primary breast tumors by immunomagnetic sorting. The pluripotency of these cells was investigated by differentiation analysis, and gene expression profiles were compared with microarrays. Differentially expressed candidate genes were confirmed by reverse transcription-polymerase chain reaction and western blot analyses. The in vivo tumorigenicity of these cells, compared with low-malignancy MCF-7 cells, was also investigated by xenograft tumor formation analysis. The results revealed that AMSCs isolated from normal tissues surrounding primary breast tumors were positive for the stem cell markers epithelial-specific antigen and keratin-19. When stimulated with basic fibroblast growth factor, a differentiation agent, these AMSCs formed lobuloalveolar structures with myoepithelia that were positive for common acute lymphoblastic leukemia antigen. The gene expression profiles revealed that, compared with cancer cells, AMSCs expressed low levels of oncogenes, including MYC, RAS and ErbB receptor tyrosine kinase 2, and high levels of tumor suppressor genes, including RB transcriptional corepressor 1, phosphatase and tensin homolog, and cyclin-dependent kinase inhibitor 2A. When injected into nude non-obese diabetic/severe combined immunodeficiency-type mice, the AMSCs did not form tumors, and regular mammary ductal structures were generated. The AMSCs isolated from normal tissue adjacent to primary breast tumors had the normal phenotype of mammary stem cells, and therefore may be promising candidates for mammary reconstruction subsequent to breast tumor resection.

Functionalized nanospheres for targeted delivery of paclitaxel.

Targeted delivery of anti-cancer agents to cancer cells is a mature line of investigation that has yet to realize its full potential. In this study we report on the development of a delivery platform with the future goal of merging two thus far parallel methods for selective elimination of cancer cells: targeted nanospheres and pretargeted radioimmunotherapy. Several clinical trials have shown the promise of pretargeted radioimmunotherapy, which leverages the specificity of antibodies for targeted cell populations and delivers a localized dose of a biotinylated radionuclide that is most often administered following binding of a biotinylated antibody and streptavidin (StA) to the target cells. The work presented here describes the development of biotinylated nanospheres based on an ABA-type copolymer comprised of a tyrosine-derived oligomer as the B-block and poly(ethylene glycol) (PEG) A-blocks. The biotinylated nanospheres encapsulate paclitaxel (PTX) to the same extent as unbiotinylated nanospheres. Efficacy of targeting was shown on CD44 positive cells in the SUM159 breast cancer cell line by incubating the cells sequentially with a biotinylated anti-CD44 antibody, StA and the biotinylated nanospheres encapsulating PTX. Targeted nanospheres achieved the half maximal inhibitory concentration of PTX on SUM159 cells at a 5-10 fold lower concentration than that of PTX applied in either non-targeted nanospheres or free drug approaches. Moreover, targeted nanospheres selectively eliminated CD44 positive SUM159 cells compared to free PTX and untargeted nanospheres. This new generation of nano-sized carrier offers a versatile platform that can be adopted for a wide variety of drug and target specific applications and has the potential to be combined with the clinically emerging method of pretargeted radioimmunotherapy.