Genetic aspects of colorectal cancer: the surgeon's view

Mechanisms and markers of carcinogenesis and neoplastic progression

Neoplastic transformation evolves over a period of time involving the progression of the cellular immunophenotype (IP) from normal to hyperplastic to dysplastic, and finally, to fully malignant IPs. Superimposed on these changes is the interaction of the initiated cell with its microenvironment, whereby the neoplastically transformed cells, through the regulation or dysregulation of cytoskeletal, integrin, protease and adhesion molecules, develop a novel manner of relation with their surrounding microenvironment. Studies of the neuroendocrine-immune network revealed that the hormonal and cytokine milieu plays an important role impacting the growth and dedifferentiation capabilities of neoplastic cells. This is further affected by the tumour cells themselves determining the constitution of this hormonal microenvironment, allowing the most aggressive and invasive of neoplastically transformed cell clones to promote their own growth and dissemination. The elucidation of the steps of the progression of cancer from premalignant to metastatic and invasive forms is of utmost importance in the differential diagnosis of neoplasms and in the establishment of more efficacious therapeutic regimens. These regimens will certainly begin to take on a more individualised form. The functional characterisation of various human malignancies as to the neoplastically transformed cells' IP, the bases of their interaction with tissue stromal elements, and the molecules involved in the humoral microenvironment of the particular stage of tumour will certainly allow for the better diagnosis, staging, prognostication and treatment of cancers in the future. This paper reviews carcinogenesis from nutritional, genetic and molecular, and humoral aspects, and discusses the importance of tumour markers in the diagnosis and therapeutic management of human cancer.

Reduced expression of APC and DCC gene protein in breast cancer

AIMS

To investigate if the adenomatous polyposis coli (APC) protein and the deleted in colorectal cancer (DCC) protein expression can be demonstrated by an immuno-histochemical method and to study the role of APC and DCC gene inactivation in the development and progression of breast cancer using colorectal cancer as a control model.

METHODS AND RESULTS

The reduced or loss of protein expression of the APC and DCC genes was studied in 27 surgical specimens of primary breast cancer using an immunohistochemical method. Reduced or lost expression was identified in 11 out of 27 samples (40.7%) for the APC gene and 15 out of 27 samples (55.6%) for the DCC gene. No statistically significant difference was observed between the reduced or lost protein expression and the histological grading of breast tumour for both the APC and the DCC gene.

CONCLUSIONS

Both gene proteins can be demonstrated by the immunohistochemical method. Reduced or loss of APC and DCC gene product were observed in 40.7% and 55.6% cases of primary breast cancer respectively. Further work is required to investigate the significance of the finding.

The p21-Ras signal transduction pathway and growth regulation in human high-grade gliomas

Deregulated p21-Ras function, as a result of mutation, overexpression or growth factor-induced overactivation, contributes to at least 30% of human cancer. This article reviews the potential role of the p21-Ras family of GTPases in the regulation of growth of high-grade gliomas and describes how targeting this oncoprotein clinically may provide a novel strategy to counteract glioma proliferation. The application of strategies directed at selectively opposing the deregulated signal transduction pathway of high-grade gliomas may be of potential therapeutic benefit and may offer a whole new arsenal of antineoplastic agents to be included in the multimodal treatment of these challenging neoplasms.