[Clinicopathological significance of expression and amplification of P21-activated kinase 1 gene in colorectal carcinoma].

OBJECTIVE: To investigate the clinicopathological value of the expression and amplification of P21-activated kinase 1 gene (PAK1) in colorectal carcinoma(CRC). METHODS: Immunohistochemistry (IHC), fluorescence in situ hybridization (FISH) and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling(TUNEL) methods were used to examine the protein expression, amplification of PAK1 and cell apoptosis in 80 cases of CRC and 30 cases of colorectal adenoma by tissue microarray. RESULTS: IHC showed an overexpression of PAK1 protein in 26% of colorectal adenomas and 62% of CRCs. Significant association was found between expression of PAK1 and tumor histological grade as well as tumor clinical stage(P<0.05). In poor-differentiated(G(3)) CRCs, PAK1 expression in 90% carcinoma was up-regulated, which was significantly higher than that in tumors of G(1/2)(51%). Overexpression of PAK1 was detected in 78% of CRCs in later clinical stages (Dukes C, D), which was significantly higher than that in early clinical stages (Dukes A,B, 53%). In addition, negative correlation between PAK1 overexpression and cell apoptosis was observed in these CRC cohorts(P<0.05). FISH revealed that amplification of PAK1 gene was examined in only 3% CRCs. CONCLUSIONS: Overexpression of PAK1 protein may play an important role in development and progression of colorectal neoplasms and it is closely associated with the malignant histological and invasive phenotype of CRCs. The expression of PAK1 in CRC may be used as one of the new molecular markers in predicting tumors malignant potential and progression.

[Screening peptides binding specifically to large intestinal cancer LoVo cells from phage random peptide library].

OBJECTIVE: To screen the polypeptides specifically binding to human large intestinal cancer LoVo cells from a phage-displayed peptide library for potential use as targeting vectors for large intestinal cancer therapy. METHODS: With the LoVo cells as the target cells and human normal large intestinal mucosal epithelial cells as the absorber cells for subtraction biopanning from a c7c phage-display peptide library, the positive phage clones were identified by enzyme-linked immunosorbent assay (ELISA) and immunofluorescence detection. The amino acid sequences of the identified peptides were deduced by DNA sequencing. RESULTS: After 3 rounds of screening, 5 positive phage clones showing specific binding to LoVo cells and containing conserved motif RPMP were obtained from the 20 randomly selected clones. CONCLUSION: Specific peptide against large intestinal cancer cells can be obtained from a phage-display peptide library for use as potential vectors for targeting therapy of large intestinal cancer.

[The significance and characteristics of chromosomal abnormalities in patients with microsatellite and chromosome stable colorectal carcinoma].

OBJECTIVE: To investigate the clinico-pathological significance and characteristics of chromosomal abnormalities in microsatellite and chromosome stable (AMCS) colorectal carcinoma (CRC). METHODS: Flow cytometry, microsatellite instability analysis and immunohistochemistry methods were used to examine the DNA ploidy, microsatellite instability and expression of mismatch repair proteins (hMSH(2) and hMSH(1)) in 156 cases of CRCs, so as to select the MACS CRCs. Comparative genomic hybridization (CGH) method was subsequently performed to analyze the status of chromosomal abnormalities of MACS CRCs. The correlation between chromosomal changes of MACS CRC and patients clinico-pathological features was further evaluated. RESULTS: Of the 156 CRCs studied, fourty-one (26%) cases were observed both diploid/near diploid DNA content and stable microsatellite sequence and all these CRCs showed normal expression of hMSH(2) and hMSH(1) protein, and thus, defined as MACS CRC. Our CGH results showed that the overall mean numbers of chromosomal abnormality of 41 MACS CRCs was 9.6. The chromosomal arms with DNA amplification (frequency > or = 10%) were 20 q (68%), 13 q (56%), 7 q (49%), 13 p (39%), 20 p (37%), 8 q (30%), 1 q (22%), 11 q (15%), 16 q (12%) and 2 p, 4 q, 10 q (10%). The chromosomal arms with DNA deletion (frequency > or = 10%) were 18 q (63%), 8 p (51%), 17 p (37%), 1 p (30%), 3 p (26%), 4 p, 13 q, 14 (15%) and 21 q, Xp (10%). In addition, there was 79% and 82% MACS CRCs in Dukes'C/D stages observed amplification of 20 q and deletion of 18 q, respectively, the frequency was significantly higher that that in Dukes'A/B stages (46%, P = 0.038 and 21%, P = 0.0009). CONCLUSIONS: The overall number of chromosomal abnormalities in MACS CRCs is similar to that of chromosomal instable (CI) CRCs, but is higher than that of microsatellite instable (MSI) CRCs. The frequent deletion of 8 p in MACS CRCs might be a special molecular event that is different from CRCs in CI and MSI pathway. Both 20 q amplification and 18 q deletion are the most frequent chromosomal abnormalities in MACS CRC and are associated closely with tumor's malignant clinical phenotype. These chromosomal changes might play important roles the development and progression of MACS CRC.

[Expression and amplification of steroid receptor coactivator-3 gene in colorectal carcinoma and its clinicopathological significance].

OBJECTIVE: To investigate the expression and amplification of steroid receptor coactivator- 3(SRC- 3) gene in colorectal carcinoma (CRC) and its clinicopathological significance. METHODS: Immunohistochemistry and fluorescence in situ hybridization (FISH) were used to detect the expression and amplification of SRC- 3 gene in CRC, and its association with patient's clinical pathological features was analyzed. RESULTS: A total of 60 patients with CRC were studied. SAR- 3 proteins were overexpressed in 23 cases (38% ). There was a significant association between SAR- 3 overexpression and neoplasm staging (P< 0.01). SRC- 3 protein was overexpressed in 62% of patients with Dukes C or D stage, whereas SRC- 3 protein was normally expressed in 74% of patients with Dukes A or B stage. As for FISH study, 47 cases were informative. High- level amplification of SRC- 3 gene was detected in 6 cases(13% ) and all showed overexpression of SRC- 3 protein. Low- level amplification of SRC- 3 was observed in 9 cases (19% ). Overexpression of SRC- 3 was detected in 6 cases. The remaining 9 of 32 patients(28% ) without amplification of SRC- 3 gene were observed with overexpression of SRC- 3 protein. In addition, 91% patients with CRC were found overexpression of SRC- 3 as well as overexpression of P53. CONCLUSION: The abnormal expression of SRC- 3 gene might impact on the function of P53 and development of CRC. There might exist some unknown mechanisms other than gene amplification of SRC- 3 to regulate its encoded protein expression in CRC.

Recurrent genetic alterations in 26 colorectal carcinomas and 21 adenomas from Chinese patients.

Colorectal cancer (CRC) is one of the most common malignancies worldwide. The incidence of CRC in the Chinese population has increased dramatically during the last two decades; however, nonrandom chromosomal alterations in Chinese patients have not been described. In the present study, comparative genomic hybridization (CGH) was applied to detect recurrent chromosome alterations in 26 primary colorectal carcinomas and 21 colorectal adenomas from Chinese patients. In CRC, several recurrent chromosomal changes were found, including gains of 8q (14/26 cases, 54%), 20q (54%), 3q (50%), 13q (50%), 5p (46%), 7p (42%), 7q (42%), and 12p (38%) and losses of 18q (65%) and 17p (42%). From comparison with previous CGH studies, the frequent gains of 3q and 12p might be distinctive occurrences in Chinese patients. The distribution of frequently found chromosomal alterations in different locations was studied. The gain of 20q was more frequently found in colon cancer (P<0.01) and the gain of 12p was more frequently found in rectal cancer. Chromosomal alterations were found in 19/21 of adenomas; the most frequent chromosomal alteration was the loss of 18q (9/21 cases, 43%). These recurrent alterations provide several starting points for the isolation of candidate oncogenes and tumor suppressor genes.