Immunoglobulin kappa and immunoglobulin lambda are required for expression of the anti-apoptotic molecule Bcl-xL in human colorectal cancer tissue.
OBJECTIVE
Aberrant expression of immunoglobulin (Ig) by cancer cells has been documented in a number of malignant tumors but its biological significance is unclear. Cancer cells overexpress anti-apoptotic molecules such as Bcl-xL. The present study aimed to examine the role of expression of Ig light-chain Igk and Iglambda in maintaining the high levels of Bcl-xL in colorectal cancer cells.


METHODS
Thirty patients with colorectal cancer were recruited to this study. Expression of Igk, Iglambda and Bcl-xL in surgically removed cancer tissue was examined by immunohistochemistry and/or flow cytometry. Using the HT29 cell line as a study platform, RNA interference (RNAi) was employed to knock out the genes of Igk and Iglambda in the cancer cell line; the expression of Bcl-xL in HT29 cells was subsequently analyzed.


RESULTS
Human colorectal cancer cells, but not normal colorectal tissue, expressed both Igk and Iglambda in the cytoplasm. High levels of Bcl-xL were detected in cancer cells. Using RNAi to knock out the genes of Igk and/or Iglambda, Bcl-xL expression in HT29 cells was significantly suppressed and the cells became apoptotic.


CONCLUSIONS
The results suggest that expression of Igk and Iglambda is required to stabilize Bcl-xL expression in cancer cells.
Yang
Shao-Bo
SB
Department of Gastroenterology (South Building), China PLA General Hospital, Beijing, PR China.
Chen
Xiao
X
Wu
Ben-Yan
BY
Wang
Meng-Wei
MW
Cai
Chang-Hao
CH
Cho
Dan-Bi
DB
Chong
Jasmine
J
Li
Ping
P
Tang
Shang-Guo
SG
Yang
Ping-Chang
PC
D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D015153:Blotting, Western; D015179:Colorectal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007146:Immunoglobulin lambda-Chains / Q000235:genetics / Q000378:metabolism*; D007136:Immunoglobulins / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D007155:Immunologic Factors / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D051020:bcl-X Protein / Q000235:genetics / Q000378:metabolism*
C494811:BCL2L1 protein, human; D014408:Biomarkers, Tumor; C014609:IgK; D007146:Immunoglobulin lambda-Chains; D007136:Immunoglobulins; D007155:Immunologic Factors; D051020:bcl-X Protein