Preliminary Characterization of a Monoclonal Antibody (AS-2) against Cell Cycle Related Proteins

A monoclonal antibody (AS-2) raised by using isolated nuclei from a human erythroleukemia cell line as immunogen is described

Intratumor Heterogeneity of K-Ras and p53 Mutations among Human Colorectal Adenomas Containing Early Cancer

The molecular pathways and the timing of genetic events during human colorectal carcinogenesis are still not fully understood. We have addressed the intratumor heterogeneity of the mutational status of the k‐ras oncogene and of the p53 oncosuppressor gene during the adenoma–carcinoma sequence by investigating 26 human colorectal adenomas containing early cancer. An intratumor comparative analysis was obtained among the adenomatous and carcinomatous component pairs. Additionally, we have analyzed 17 adenomas having cancer in the near vicinity. The adenomatous components of the adenomas containing early cancer and the adenomas having cancer in the near vicinity had comparable frequencies for k‐ras mutations (28 and 47%) but different for p53 mutations (52 and 7%, p‐value = 0.01). Interestingly, the adenomatous and carcinomatous components of the adenomas containing early cancer were rarely heterogeneous for the k‐ras mutational status (only in 13% of the cases) but were characterized by heterogeneity of the p53 status in 59% of the cases (p‐value < 0.01). In addition, the mutations of p53 for the adenomatous components of the adenomas containing early cancer were statistically significantly associated with severe dysplasia (p-value = 0.01). Intratumor homogeneity of k‐ras status during the human colorectal adenoma–carcinoma sequence suggests that the role of k‐ras is more related to tumor initiation than to tumor progression. On the contrary, intratumor heterogeneity of p53 mutations indicates that the type of the p53 mutations may also be relevant for selection and expansion of new subclones leading to tumor progression

K-ras2 Activation and Genome Instability Increase Proliferation and Size of FAP Adenomas

The possible role of K‐ras2 mutations and aneuploidy toward increase of proliferation and adenoma size in Familial Adenomatous Polyposis (FAP) adenomas is not known. The present study addresses these issues by investigating 147 colorectal adenomas obtained from four FAP patients. The majority of adenomas had size lower than or equal to 10 mm (86%), low grade dysplasia (63%), and were preferentially located in the right colon (60%). Normal mucosa samples were obtained from 19 healthy donors. Three synchronous adenocarcinomas were also investigated. K‐ras2 mutation spectrum was analysed by PCR and Sequence Specific Oligonucleotide (SSO) hybridization, while flow cytometry (FCM) was used for evaluating degree of DNA ploidy and S‐phase fraction. Overall, incidences of K‐ras2 mutations, DNA aneuploidy and high S‐phase values (>7.2%) were 6.6%, 5.4% and 10.5%, respectively. In particular, among the adenomas with size lower than 5 mm, K‐ras2 mutation and DNA aneuploidy frequencies were only slightly above 1%. Statistically significant correlations were found between K‐ras2 and size, DNA ploidy and size and K‐ras2 and S‐phase (p). In particular, among the wild type K‐ras2 adenomas, high S‐phase values were detected in 8% of the cases versus 57% among the K‐ras2 mutated adenomas (p=0.0005). The present series of FAP adenomas indicates that K‐ras2 activation and gross genomic changes play a role toward a proliferative gain and tumour growth in size