Dominant expression of 85-kDa form of cortactin in colorectal cancer.
OBJECTIVE
Cortactin is commonly expressed in several human cancers, which may alter their invasive or metastatic properties. Eighty five kilodalton form (p85) and 80-kDa form (p80) of cortactin are two separate bands in SDS-PAGE representing different conformational states. The objective of this study was to investigate cortactin expression in colorectal cancer (CRC).


METHODS
Cortactin expression was studied in an eight paired laser capture microdissection (LCM) CRC tissues and matched non-cancerous epithelia by immunoblotting. The expression in 58 CRC and two cell lines, HCT8 and HCT116, was studied respectively by immunohistochemistry and confocal laser scanning immunofluorescence.


RESULTS
Dominant expression of p85 was identified in LCM-procured CRC tissues compared with equal intensity of p85 and p80 forms in non-cancerous tissues, while the amount of total cortactin was approximate. Immunohistochemistry analysis demonstrated that cortactin located in the cytoplasm of tumor cells and adjacent non-cancerous cells, and its expression was negatively correlated with TNM staging and lymphatic invasion status. However, the invasion fronts in 3 of 58 primary tumors and 28 of 39 available lymph node metastases were intensively stained. Further, immunofluorescence analysis showed that cortactin was distributed in cytoplasm and enriched in the front of the extending lamellipodia at adhering side of cultured cancer cells.


CONCLUSIONS
Our results demonstrated the dominant expression of p85 form of cortactin in CRC for the first time. The enrichment of cortactin in the invasion front of some tumor cells and in the extending lamellipodia of cultured cancer cells suggests that cortactin may help cancer cell movement.
Zhang
Lian-Hai
LH
Beijing Cancer Hospital, Beijing Institute for Cancer Research, Peking University School of Oncology, Beijing 100034, China.
Tian
Bo
B
Diao
Li-Rong
LR
Xiong
Yong-Yan
YY
Tian
Su-Fang
SF
Zhang
Bian-Hong
BH
Li
Wen-Mei
WM
Ren
Hui
H
Li
Yan
Y
Ji
Jia-Fu
JF
D014408:Biomarkers, Tumor / Q000032:analysis*; D002465:Cell Movement; D015179:Colorectal Neoplasms / Q000737:chemistry* / Q000473:pathology; D051356:Cortactin / Q000032:analysis*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005455:Fluorescent Antibody Technique; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000737:chemistry; D053685:Laser Therapy; D008297:Male; D042282:Microdissection / Q000379:methods; D008875:Middle Aged; D009367:Neoplasm Staging; D013997:Time Factors; D014407:Tumor Cells, Cultured
D014408:Biomarkers, Tumor; D051356:Cortactin