This localization places the CD20 gene near the site of the t(11;14)(q13;q32) translocation that is found in a subgroup of B cell-lineage malignancies.
In gastrointestinal carcinomas similarly examined, CK 20 has been detected in almost all cases (50/52) of colorectal adenocarcinomas, including all grades of differentiation and malignancy and also metastatic tumors, whereas CK 20 immunostaining in gastric carcinomas has been found less consistent and more heterogeneous.
We used a reverse transcriptase-polymerase chain reaction (RT-PCR) to detect circulating breast cancer cells in venous blood samples before operations and assessed cytokeratin-19 (CK-19) and cytokeratin-20 (CK-20) as target mRNA markers in the blood of healthy donors (n=6) and breast cancer patients (n=30) with American Joint Committee on Cancer stages 0 to IIIa.
An understanding of CD20 function from signal transduction to biological implications may prove important for the mechanistic understanding of the treatment of certain types of cancer.
Although its coexpression has been reported in up to 10% cases of precursor T-cell lymphoblastic lymphoma, the coexpression of both CD20 and CD79a has not been described in mature T-cell malignancies.
RT-PCR products for CK8 and CK18 were detected in all cancer cell lines, but only 16, 5, and 11 cell lines provided evidence for CK19, CK7, and CK20 transcription.
These results characterize low-level, epithelial cell-specific CK20 expression in infiltrated lymph nodes from subjects with noncolorectal cancer types and demonstrate the potential advantages of detecting circulating epithelial cells by quantitative PCR.
Cell lines of different lineages and bone marrow and peripheral stem cells from patients without epithelial cancer have been examined for the transcription of the cytokeratin-20 (CK20) and mammaglobin messages prior to and after stimulation with different cytokines in a total of 370 liquid cultures.
CK20 mean values were elevated in cancer patients (P<0.001) and defined a subgroup (38%) who showed CK20 levels at least 100-fold above the highest value of the healthy control group.
CK-20 expression was observed in the peripheral blood of 19 out of 47 (40.4%) patients with malignant tumors, 2 out of 9 (22.2%) patients with benign tumors and 3 out of 15 (20%) patients with non-tumor diseases.
The expression of CK20 mRNA by RT-PCR was investigated in bone marrow, portal vein and peripheral blood in 58 colorectal cancer patients and 12 controls without known cancer.
Since rituximab, a chimeric monoclonal anti-CD20 antibody, was introduced into clinical practice in 1997, data regarding its benefit in terms of response rate, quality of response, progression-free survival and overall survival in B-cell lymphoid malignancies continues to expand.
Thus, RRBL1 may be useful not only for analyses of mechanisms for the absence of CD20 expression in vitro but also for exploration of therapies against CD20- B-cell malignancies in vivo.
Importantly, in contrast to parental NK-92, CD20-specific NK cells efficiently lysed CD20 expressing but otherwise NK-resistant established and primary lymphoma and leukemia cells, demonstrating that this strategy can overcome NK-cell resistance and might be suitable for the development of effective cell-based therapeutics for the treatment of B-cell malignancies.
Targeting type I IFNs to sites of B-cell lymphoma by fusion to anti-CD20 antibodies represents a potentially useful strategy for treatment of B-cell malignancies.