Characterization of a renal cell carcinoma cell line suitable as a target for immunological studies in vitro and in the nu/nu mouse

Low frequency of positive telomerase activity in a chromophobe subtype of renal cell carcinoma

PURPOSE

In malignant tumors, telomerase reactivation plays an important role in the acquisition of cellular immortality. We evaluated the telomerase activity in renal cell carcinomas (RCCs) with special reference to their clinicopathologic features.

MATERIALS AND METHODS

Telomerase activity was examined in 47 RCCs and 9 RCC cell lines by telomeric repeat amplification protocol assay (TRAP). The telomere lengths were assessed by Southern analysis of terminal restriction fragments (TRFs) generated by Hinfl-digested DNA.

RESULTS

Thirty-six (77%) of the 47 RCCs and all 9 RCC cell lines showed telomerase activity, whereas no activity was detected in any of 30 normal kidneys. When the tumors were histopathologically classified, only one (17%) of the 6 chromophobe cell carcinomas was telomerase-positive. This frequency was significantly low (p < 0.001) when compared with those in clear cell RCCs (93%; 26/28). In 40 of the 47 patients, DNA from the tumor tissues and the paired normal kidneys was available for analysis of the TRF lengths. No tumor showed elongated TRF length compared to its paired normal kidney. Regarding the relationship between telomere length and telomerase activity, 23 (74%) of the 31 telomerase-positive RCC and 6 (67%) of the 9 telomerase-negative RCC exhibited reduced TRF. There was no significant correlation between the telomere reduction and telomerase activity.

CONCLUSION

The mechanism for preventing telomere shortening may differ according to RCC subtype. Alternatively, telomerase-negative tumors may have yet to reach the immortal stage when they progress to clinical cancer. The telomerase activity status may contribute to the biological potential and the prognosis of RCCs.

Contribution of chromosome 9p21-22 deletion to the progression of human renal cell carcinoma

To investigate the possible role of genomic aberrations of chromosome 9p21-22 in the tumorigenesis of human renal cell carcinoma (RCC), 10 RCC cell lines, 55 primary RCCs and 5 metastatic lesions were studied by Southern blotting and polymerase chain reaction-based analysis. Nine of 10 RCC cell lines showed a homozygous deletion of MTSI/CDKN2/(p16), while only 1 in 55 primary tumors had this deletion. Loss of heterozygosity on 9p21-22 was observed in 5 of 10 informative primary RCCs from patients with metastasis, but in only 4 of 31 informative tumors (13%) without metastasis (P = 0.025). Futhermore, 3 of 5 metastatic tumors (60%) showed hemi- or homozygous deletion of MTSI/CDKN2. These results indicate that the 9p21-22 deletion may be a relatively late event in RCC tumorigenesis and could be associated with RCC metastasis.

Expression of cell adhesion molecules in an established and characterized new human renal cell cancer line, CCF-RC7

In order to investigate the importance of cell adhesion molecules (CAMs) in renal cell carcinoma (RCC), a cell line, designated as CCF-RC7, was established from a human RCC of the clear cell type. CCF-RC7 was passaged over 50 times in vitro for 3 1/2 years. The cell line has an epithelial morphology and a doubling time of 30 h, forming colonies in soft agar with an average efficiency of 10.4% and producing clear cell tumors in athymic nude mice. CCF-RC7 cells have an aneuploid-hypotetraploid karyotype with a modal chromosome number of 82 and rearrangements in chromosomes 9, 12 and 14. Immunohistochemical and flow immunocytometric analyses revealed high expression of ICAM-1 (CD54), and Hermes antigen (CD44), which was significantly upregulated by cytokine and PMA treatment. VLA-4 was expressed on approximately 20% of tumor cells and could not be altered by cytokine or PMA stimulation. High expression of sialyl Lewis X was also demonstrated by immunohistological examination. This newly characterized cell line will serve as a useful model for the study of CAMs during hematogenous metastasis and host defense mechanisms in human RCC.

Assessment of human genitourinary tumors and chemosensitivity testing in 3-dimensional collagen gel culture

A recently described collagen gel culture technique has been modified to evaluate the growth characteristics and chemosensitivity patterns of genitourinary neoplasms. Fresh human surgical explants incorporated radiolabeled DNA precursors [H3)thymidine or deoxyuridine) in 97% of 38 patient specimens (18/19 bladder, 3/3 prostate, 2/2 testis, 13/14 renal), after being maintained for three to 13 weeks/passage, with several specimens reaching their sixth passage (20 months). Control cellular DNA incorporation ranged from five to 90% (#cells labeled/#cells evaluated), with median labeling for bladder 30%, prostate 80%, testis 90%, and renal 80%. Original histopathologic classification was maintained in all cases. Tumor volume and glucose consumption were other measurable parameters. Seventy-three surgical specimen cultures were treated with chemotherapeutic agents after a minimum of four weeks in culture. Single agent exposures were 24 hours at 1X and 10X reported peak plasma concentrations. Combination agents were sequenced as in current clinical protocol for bladder tumors and fourteen day continuous fluorodeoxyuridine (FdURD) exposure for renal tumors. Sensitivity was found in 1/2 prostate and 1/10 renal tumors to Adriamycin, 8/15 bladder and 1/2 testis tumors to cisplatin, 11/28 renal tumors to FdURD and 6/16 bladder tumors to MVAC combination chemotherapy. This culture system offers the advantages of in vivo-like solid tumor growth, a high culture success rate, longevity in culture, maintenance of the primary histopathology and reproducible chemosensitivity response.

Chromosome analysis of a newly established renal carcinoma cell line

A renal cell carcinoma has been established as a cell line in vitro. Repeated chromosome analyses of the cell line revealed a stable clone with the modal chromosome number 80 and three pairs of marker chromosomes, M1-M3. M1 and M2 resulted from a translocation between a chromosome #3 deleted in band p14 and a normal #7: M1 = der(3)t(3;7) (:3p14----cen----3q24::7q21----7qter), and M2 = der(7)t(3;7)(3qter----3q24::7q21----cen----7pter ). M3 was a small metacentric chromosome, probably consisting of the centromeric portion of a #3: del(3)(:p14----cen----q12:). No other structural changes were present. Our findings are in agreement with those of previous studies, stating that rearrangements of 3p12-14 are primary cytogenetic events in renal cell carcinomas, even though this can only be inferred in this case. Thus, this cell line may be useful for further molecular and biochemical studies.

Lymphokine-activated killer (LAK) cells from human intestinal mucosa: cytotoxic activity against tumor cell lines and modified self but not autologous and allogeneic colon cancer cells

Patients with colorectal cancer respond poorly to in vivo immunotherapy with lymphokine-activated killer (LAK) cells generated from peripheral blood mononuclear cells (PBMC). We postulated that gut-derived immune cells could be a more relevant source of LAK cells directed against colorectal cancer. Intestinal lamina propria mononuclear cells (LPMC) and colonic adenocarcinoma cells were isolated from operative specimens by combination of mechanical and enzymatic dissociation methods. LAK cells were generated by culturing PBMC and LPMC with recombinant interleukin 2 (IL2), with and without OKT3 monoclonal antibody, in short- (4 days) and long-term (21 days) cultures. Other cultured tumor cells, normal intestinal fibroblasts, and hapten-modified autologous LPMC were used as control targets. Cytotoxicity was measured by a 4-hr 51Cr release assay. Short-term cultured LAK cells exhibited a strong to moderate degree of killing against normal intestinal fibroblasts, hapten-modified self cells, and four different tumor cell lines. Instead, fresh colon cancer cells were resistant to cytotoxicity, regardless of their degree of histologic differentiation and the autologous or allogeneic nature of the LAK cells. Long-term culture with IL2 remarkably increased LAK cell activity against all tumor targets, but not against colonic adenocarcinoma cells. The results of this study, showing that freshly isolated colon cancer cells are intrinsically resistant in vitro to highly activated cytotoxic effector cells, may explain the poor clinical results observed in human trials with in vivo administration of IL2 or LAK cells.