Improvement of breast cancer cell detection by immunomagnetic enrichment

Cancer-associated fibroblasts promote proliferation of endometrial cancer cells

Endometrial cancer is the most commonly diagnosed gynecologic malignancy worldwide; yet the tumor microenvironment, especially the fibroblast cells surrounding the cancer cells, is poorly understood. We established four primary cultures of fibroblasts from human endometrial cancer tissues (cancer-associated fibroblasts, CAFs) using antibody-conjugated magnetic bead isolation. These relatively homogenous fibroblast cultures expressed fibroblast markers (CD90, vimentin and alpha-smooth muscle actin) and hormonal (estrogen and progesterone) receptors. Conditioned media collected from CAFs induced a dose-dependent proliferation of both primary cultures and cell lines of endometrial cancer in vitro (175%) when compared to non-treated cells, in contrast to those from normal endometrial fibroblast cell line (51%) (P<0.0001). These effects were not observed in fibroblast culture derived from benign endometrial hyperplasia tissues, indicating the specificity of CAFs in affecting endometrial cancer cell proliferation. To determine the mechanism underlying the differential fibroblast effects, we compared the activation of PI3K/Akt and MAPK/Erk pathways in endometrial cancer cells following treatment with normal fibroblasts- and CAFs-conditioned media. Western blot analysis showed that the expression of both phosphorylated forms of Akt and Erk were significantly down-regulated in normal fibroblasts-treated cells, but were up-regulated/maintained in CAFs-treated cells. Treatment with specific inhibitors LY294002 and U0126 reversed the CAFs-mediated cell proliferation (P<0.0001), suggesting for a role of these pathways in modulating endometrial cancer cell proliferation. Rapamycin, which targets a downstream molecule in PI3K pathway (mTOR), also suppressed CAFs-induced cell proliferation by inducing apoptosis. Cytokine profiling analysis revealed that CAFs secrete higher levels of macrophage chemoattractant protein (MCP)-1, interleukin (IL)-6, IL-8, RANTES and vascular endothelial growth factor (VEGF) than normal fibroblasts. Our data suggests that in contrast to normal fibroblasts, CAFs may exhibit a pro-tumorigenic effect in the progression of endometrial cancer, and PI3K/Akt and MAPK/Erk signaling may represent critical regulators in how endometrial cancer cells respond to their microenvironment.

Usefulness of transcription-reverse transcription concerted reaction method for detecting circulating tumor cells in patients with colorectal cancer

PURPOSE

The CellSearch system (Veridex, LLC) is useful for detecting circulating tumor cells (CTCs) in various carcinomas, including colorectal cancer (CRC); however, there are some problems associated with its clinical use. A transcription-reverse transcription concerted reaction (TRC) method, which is a PCR-based technique producing more stable and reliable results, because it is a more simplified process compared with the conventional techniques, has been introduced for detecting micrometastasis in some carcinomas. We aimed to demonstrate the effectiveness of TRC method in the CTC detection.

METHODS

We compared the two methods for the sensitivity for CTC detection using the colon cancer cell line and 42 whole-blood samples from patients with advanced or metastatic CRC. Furthermore, 25 patients with metastatic CRC were enrolled to investigate the correlation between CTC detection and prognosis in both methods.

RESULTS

The sensitivity of the TRC method was similar to that of the CellSearch system. The overall survival rate was significantly worse in the patients diagnosed as CTC-positive by the TRC method than in those diagnosed as CTC-negative; this finding was similar to the prognosis indicated by the CellSearch system. However, clinically, the TRC method could detect CTCs more rapidly and at a reduced cost compared with the CellSearch system.

CONCLUSIONS

The TRC method seems to be a useful alternative to the CellSearch system for clinically detecting CTCs in patients with metastatic CRC.

Report of the Tumor Evaluation Committee workshops at ISHAGE 2001

Multiple factors impact polymerase chain reaction (PCR) detection of tumor cells ranging from the fundamental, such as selection of targets for amplification, to the practical, including the timing of sample processing, granulocyte contamination and anticoagulant used. Much more work, including standardization studies, remains to be performed. Tumor enrichment can be achieved either by positive selection, generally by use of antibodies or by depletion of (CD45(+)) hematopoietic cells. Both approaches work and each has advantages and disadvantages. Enriched tumor cells can be further analyzed for expression of prognostic markers. A future area of emphasis should be to establish a dialogue between practitioners of tumor detection and developers of new therapies who are in search of surrogate markers of outcomes.

Detection and enrichment of disseminated renal carcinoma cells from peripheral blood by immunomagnetic cell separation

We have established an immunomagnetic separation procedure for the detection of circulating tumor cells in the peripheral blood based on the magnetic cell sorting (MACS) technique. In previous in vitro experiments, renal-cell carcinoma (RCC) cells were mixed with peripheral blood. In dilutions of 1:200 to 1:107 tumor cells per mononuclear blood cells, an average recovery rate of 84% of tumor cells was determined. In our study, 104 peripheral blood samples from 59 renal carcinoma patients were analyzed. MACS resulted in significant depletion of leukocytes, permitting a search for tumor cells on just 1 slide. Analyzing 8 ml of peripheral blood per patient, 19/59 RCC patients carried disseminated tumor cells (32%) in the range of 1 to 38 cells (median 8). Interestingly, for the cytokeratin-positive (CK+) patient group, we found a correlation between tumor cell number and grading (G2 vs. G3) and an increased number of CK+ patients with advanced tumor stage. MACS appears to be an efficient technique to detect disseminated tumor cells in peripheral blood.

Influence of Preharvest Tumor Cell Contamination in Bone Marrow or Blood Does Not Predict Resultant Tumor Cell Contamination of Granulocyte Colony-Stimulating Factor Mobilized Stem Cells

Tumor cell contamination of stem cell collections harvested from breast cancer patients is a common phenomenon described by several investigators but with findings that vary among reports. Although so-called co-mobilization of these cells has been hypothesized, the origin of tumor cell contamination in stem cells is still unknown. A total of 47 G-CSF mobilized stem cell grafts from patients with nodal-positive (n = 30), chemosensitive metastatic (n = 11), and 5 women with inflammatory breast cancer were evaluated for cancer cells by immunocytochemistry. Additionally, 40 bone marrow aspirations and 23 peripheral blood samples collected prior to apheresis and after one to two cycles of conventional chemotherapy were available for examination. Tumor cell contamination of leukapheresis correlated best with preharvest blood state. This was valid when the nominal (positive/negative) presence of tumor cells in blood was compared to the nominal presence of tumor cells in apheresis samples and when the it was correlated to the tumor cell load of apheresis samples (TCL = tumor cells per 10(6) nucleated cells investigated). The correlation between blood and stem cells was better (nominal and quantitative) than that between marrow and stem cells, despite the larger sample size of marrow aspirations. The presence or absence of cancer cells in apheresis samples could not be safely predicted by the presence or absence of tumor cells in marrow or blood alone. Diagnostic specificity seems to improve from a combination of results from marrow and blood analysis. No correlation was found in quantitative analysis of tumor cell contamination between marrow and blood. In conclusion, the results suggest that blood and bone marrow represent different compartments for epithelial cancer cells and that contaminating tumor cells in stem cell harvests may be derived from the blood and/or marrow compartment. The tumor cell contamination of a stem cell harvest cannot be safely predicted by a preceding blood or marrow analysis.

Urokinase-like plasminogen activator receptor expression on disseminated breast cancer cells

Disseminated tumor cells are detected frequently in bone marrow, peripheral blood, and cytokine-mobilized peripheral blood cell products of women undergoing high-dose therapy for breast cancer. Several attempts were made to purge autografts from contaminating cancer cells; however, the biological and clinical impact of these contaminations has not been clarified so far. Expression of distinct phenotypes is a surrogate marker for metastatic behavior of cancer cells. The expression of the urokinase-like plasminogen activator receptor seems to be a factor of high importance. It is not expressed by normal mammary tissue. Disseminated cancer cells from marrow, blood, and stem cell products have been investigated by double-stain technique for urokinase-like plasminogen activator receptor (uPA-R) expressing cytokeratin-positive cells. uPA-R(+)/CK(+) cells could be found in all qualities of samples; however, significantly less in G-CSF-mobilized peripheral blood stem cells compared to samples of other provenance (p = 0.02). It can be concluded that epithelial cells of malignant phenotype occur in blood, marrow, and autografts of breast cancer patients. Populations of disseminated tumor cells are phenotypically heterogeneous. Reduced uPA-R expression on cancer cells from leukapheresis samples might suggest a less aggressive nature of these cells compared to disseminated cells found in bone marrow. Furthermore, the data suggest that the phenotype of tumor cell contamination in leukapheresis products differs significantly from those of disseminated cancer cells in bone marrow or blood.

Immunomagnetic tumor cell selection--implications for the detection of disseminated cancer cells

BACKGROUND

The optimal method for the detection of disseminated epithelial cancer cells has not yet been found. The standard method, using immunocytochemistry, offers a sensitivity of up to 10(-6). Molecular methods such as cytokeratin-19 RT-PCR are about 10 times as sensitive, but they are hampered by interference such as illegitimate gene expression.

STUDY DESIGN AND METHODS

Immunomagnetic bead selection of epithelial cancer cells using conjugates directed against the human epithelial antigen (HEA) followed by immunocytochemistry testing was investigated in this trial.

RESULTS

No cytokeratin-positive cells could be enriched from 56 control samples. In 104 clinical samples of bone marrow aspirations, PBPC collections, and venous blood obtained from breast cancer patients, the cytokeratin-positive rate increased significantly, from 29.9 percent before selection to 54.8 percent after enrichment. Even the yield of detected cancer cells was significantly higher after selection. Up to 2.5 x 10(8) MNCs were easily processed. However, the mean cancer cell recovery after HEA enrichment was only 24.4 percent. Subsequently, selected epithelial cells were successfully immunophenotyped by use of a double-stain technique detecting cytokeratin-positive cells and the urokinase-like plasminogen activator receptor.

CONCLUSION

HEA bead selection in combination with the standard immunocytochemistry method is a powerful and specific tool for the detection of disseminated cancer cells without false-positive results. Furthermore, it delivers enough cells for subsequent investigations such as characterization studies.