Expression of BCL‐6 and cyclin D in human colon carcinoma

Cyclin D, an upregulated gene of colorectal cancers is used as a diagnostic marker for colon carcinomas. BCL‐6 is a transcriptional regulator important for lymphocyte survival. Microarrays show BCL6 is seven‐fold upregulated in colorectal cancers compared to controls. We tested whether BCL‐6 could be used as a diagnostic marker in moderately differentiated colonic adenocarcinomas by comparing the proportion of BCL‐6 staining to Cyclin D control. With IRB approval, human neoplastic colorectal masses were obtained from surgical pathology specimens on 31 subjects. Antibodies for BCL‐6 and Cyclin D were tested in control tissues and on all sections with antigen baring, secondary and tertiary staining for both markers, n=62. Sections were graded by 2 pathologists unaware of the slides' identity. Data were also evaluated for inflammation, mucin, positive lymph nodes and polyp origin. Analysis by ANOVA included 4 groups, BCL‐6 positive, cyclin D positive, tumors positive for both or negative for both markers. Of the 100% surgically diagnosed cases, BCL‐6 was positive in 16% and cyclin D positive in 29%. BCL‐6 was significantly related to cases “mucinous” cases (p<0.001). Marked inflammation (p<0.01) was noted in tumors positive for both markers. This study attempted the validation of another biomarker for colon cancer. A need exists to predict treatment responsiveness. Sponsor: Sarah Morrison grant, UMKC