Oncogenes, suppressor genes, and carcinogenesis

Immunohistochemical Expression of c-erbB-2 in Human Breast Cancer by Monoclonal Antibody: Correlation with Lymph Node and Er Status

c-erbB-2 Protein expression was investigated in a series of fifty primary breast cancers by means of a specific monoclonal antibody and immunocytochemistry. Specific staining was observed at the plasma membrane level of neoplastic cells, according to the reported localization of c-erbB-2 protein. Sixty-four percent of tumors scored positive, with a variable amount of stained cells. The rate of protein expression was found to exceed the reported gene amplification. No relationship was observed between c-erbB-2 protein staining and age, meno pausal status or histologic subtypes. An inverse association was found between c'erbB-2 protein staining and estrogen receptor content of tumors, assayed by immunocytochemistry. A positive relationship was observed between c-erbB-2 protein expression and presence of axillary node metastasis. These findings suggest that c-erbB-2 protein expression is a marker of tumor aggressiveness and that its prognostic power deserves further investigation both in node-positive and node-negative patients.

Prognostic implications of epidermal growth factor receptor immunoreactivity in squamous cell carcinoma of the oral mucosa

To evaluate the clinical significance of the expression of epidermal growth factor receptor (EGFr) in oral squamous cell carcinoma (SCC), 100 formalin-fixed, paraffin-embedded cases of this tumour and ten samples of normal oral mucosa were immunostained with a monoclonal anti-EGFr antibody using an immunoalkaline phosphatase (APAAP) technique. EGFr immunoreactivity was detected in 36 of 100 tumours and in all samples of normal mucosa. Tumour cells demonstrated distinct membrane staining in 14 cases and predominantly cytoplasmic staining in 22 additional cases. EGFr was exclusively localized on the cell membrane of normal epithelial cells. Kaplan-Meyer survival curves and Cox proportional hazard regression models were used to assess overall survival and disease-free survival. A significant positive correlation was shown between EGFr membranous immunoreactivity and prolonged survival, in both univariate and multivariate analyses. Accordingly, patients with oral SCC showing down-regulated expression of membranous EGFr, who are more likely to suffer recurrence and death, should be strictly followed up and possibly treated with more aggressive therapeutic regimens.

Oncogene expression is modulated by recombinant human interferon-beta in human breast-cancer cells

The effect of recombinant human interferon-beta on growth and oncoprotein expression was investigated in several human breast-cancer cell lines with different characteristics. All cell lines tested were sensitive to the antiproliferative action of the drug, regardless of their estrogen sensitivity. The maximal inhibition of cell proliferation was seen after 6 days of treatment. In estrogen-sensitive CG-5 and ZR-75-1 cells, but not in MDA-MB-453 estrogen-insensitive cells, a reduction in c-myc and c-erbB2 oncoproteins occurred after 48-72 hr and became more pronounced after 120-168 hr of treatment, suggesting that this down-regulation is not direct but is mediated by undefined molecular mechanisms. The time-course of the IFN-mediated decrease in oncoproteins seems to indicate that this event is not strictly related to the IFN-regulation of cell proliferation. The expression of c-erbB2 and c-myc was also analyzed, after recombinant human interferon-beta treatment, at the mRNA level in CG-5 cells. Surprisingly, no statistically significant variation of c-erbB2 or of c-myc mRNA was found either before or after 120-168 hr. Thus, we surmise that the observed reduction of oncoproteins may be due to post-transcriptional mechanisms.

Expression of TGF-Alpha and c-fos in Conventional and Basaloid Squamous Cell Carcinoma of Floor of Mouth

Basaloid squamous cell carcinoma of the floor of the mouth is a newly recognized variant of squamous cell carcinoma that has a very aggressive behavior. To characterize basaloid squamous cell carcinoma at the molecular level, the authors studied the immunohistochemical expression in this tumor of the oncogene c-fos and of transforming growth factor-alpha. Eight cases of basaloid squamous cell carcinoma were evaluated by immunoperoxidase staining and compared to 16 squamous cell carcinomas of the floor of the mouth that ranged from well to poorly differentiated. The expression of c-fos was stronger in basaloid squamous cell carcinoma and poorly differentiated squamous cell carcinoma than it was in well-differentiated squamous cell carcinoma. Conversely, transforming growth factor-alpha expression was much stronger in well-differentiated squamous cell carcinoma than in basaloid squamous cell carcinoma or poorly differentiated squamous cell carcinoma. Moderately differentiated squamous cell carcinomas showed weak to moderate immunostaining for transforming growth factor-alpha but stained intensely for c- fos, which was consistently expressed at a high level in these tumors. This study confirms the poorly differentiated nature of basaloid squamous cell carcinoma, which has a similar pattern of staining as poorly differentiated. The decreased expression of transforming growth factor-alpha in basaloid squamous cell carcinoma may be related to the low degree of differentiation of this tumor since transforming growth factor-alpha tends to have higher levels of expression in well-differentiated tumor cells. Int J Surg Pathol 3(3):169-174, 1996

Selection of appropriate cellular and molecular biologic diagnostic tests in the evaluation of cancer

In this article, the use of cellular and molecular markers to diagnose and stage tumors is discussed. Their role in the evaluation of tumor prognosis and tumor susceptibility also is covered. The immunologic, cytogenetic, and molecular phenotype is discussed. Traditional markers are compared with newer methodologic approaches including evaluation of oncogenes, tumor suppressor genes, and genes that predict tumor susceptibility. These discussions are presented in relation to specific tumors. Finally, statements one might use to decide which tests to perform are presented.

Oncogenes in gynecological tumors

Evidence is increasing that proto-oncogenes and cancer suppressor genes are involved in the development and/or progression of gynecological malignancies. While histopathologic examination remains an indispensable tool of the surgical pathologist in the diagnosis and evaluation of patients with gynecological malignancies, the advancement to technology and the development of new knowledge regarding neoplastic transformation are providing a basis for new opportunities to improve patients care. These new opportunities will depend on the use of the skills and reagents developed in the basic medical science laboratories. Thus, it is important for those in the field of diagnostic pathology to begin to acquire a knowledge of proto-oncogenes and cancer suppressor genes as well as a basic understanding of the techniques used to detect and evaluate them.

Oncogenes: a review of their clinical application

One objective of this review is to sort through and collate the recent data that suggest that human cellular oncogenes, which have been implicated as the etiologic agents in both animal and human malignancies, have also the potential to be employed as clinical tools in the struggle against cancer. For nearly 10 years, reports have been suggesting that advantage can be taken of cellular oncogenes as to their use as diagnostic and prognostic indicators of cancer and eventually as therapeutic cancer agents. It is also the purpose of this review to give an objective evaluation of these predictions. Moreover, this review will try to highlight some of the significant advances in this most rapidly evolving field of biology. Although the enormity of what has been learned about cellular oncogenes is nothing less than impressive, it is the view here that the routine implementation of oncogenes into the clinical setting will not become evident as early as the many predictions had purported.

An analysis of abnormalities of the retinoblastoma gene in human ovarian and endometrial carcinoma

The altered expression of the human retinoblastoma (RB) gene has been demonstrated to play an important role in the pathogenesis of RB and other tumors. To determine whether the RB gene might be involved in the pathogenesis of human ovarian and endometrial cancer, DNA from 24 human ovarian tumors, 3 normal ovaries, 3 endometrial carcinomas, and 1 endometrial hyperplasia was examined with an RB complementary DNA probe. Evidence for homozygous deletion of the RB gene was observed in only one specimen. Interestingly, the specimen was an endometrioid tumor of the ovary of low malignant potential (LMP). This patient experienced rapid progression of the tumor and died 8 months after diagnosis. Abnormalities of the RB gene may be involved in the aggressive biologic behavior of certain forms of ovarian carcinoma, particularly those of LMP.

The future anatomic pathology laboratory for molecular diagnosis and prognosis: circa 1990-95

Molecular biology provides analytical tools for the study of human disease. These clinical assays can help make a diagnosis, predict a prognosis, or elucidate the pathogenesis of poorly understood diseases. The detection and/or quantitation of specific genes, messenger RNA's, and their protein products provide diagnostic and prognostic information for physicians. Illustrative applications of some of these techniques in human virus infection and breast cancer will suggest the future direction that an anatomic pathology laboratory should consider if it is to provide optimal and competitive service to physicians.

Intercellular communication in bronchial epithelial cells: review of evidence for a possible role in lung carcinogenesis

A challenging aspect of lung carcinogenesis is the elucidation of the mechanisms which permit initiated bronchial epithelial cells to attain a growth advantage over normal bronchial epithelial cells, and subsequently evolve into a malignant phenotype. In this review, the effects of interactions between normal and transformed cells, and the potential role of representative extrinsic factors on cell-cell communication are discussed. Evidence is presented to show how cell injury and the effects of serum and calcium may affect morphology and communication, and tumor development. A large number of autocrine-paracrine factors (e.g., TGF beta, TGF alpha) are released by bronchial epithelial cells. These factors may inhibit or promote the proliferation of normal and transformed bronchial epithelial cells, respectively. The ability of certain injurious and tumor promoting agents (e.g., formaldehyde, TPA) to select for the transformed phenotype may involve selective cell injury, the induction of terminal differentiation and an inhibition of gap junction communication among normal BE cells.

Influence of 5-azacytidine on differentiation and growth in rat nervous system tumor cell lines

In vitro studies with permanent cell lines derived from ENU-induced rat CNS and PNS tumors have shown that substances acting on second messenger systems as well as glucocorticoids have a cytostatic effect at high cell densities, but enhance proliferation at low densities. The nontoxic cytostatic effects are partially accompanied by the induction of differentiation monitored by immunocytochemistry with antibodies against GFAP, S-100 and PKC (alpha,beta). Cell differentiation with or without the influence of the drugs applied could be highly facilitated in some (CNS), but not all (PNS) types of tumor cells from neuroectodermal origin by pretreatment of cultures with 5-azacytidine under demethylating noncytostatic conditions. The implications of our results are relevant for molecular neurobiology and might offer new therapeutical approaches and may provide models for neurotoxicology.

New cancer markers

In recent years many new and improved cancer markers have become available. From a clinical point of view, the most useful of the new markers include CA 19-9 for pancreatic adenocarcinoma, CA 125 for epithelial ovarian cancer, CA 15-3 for breast cancer, prostate specific antigen for prostatic adenocarcinoma, placental alkaline phosphatase for testicular seminomas and neuron-specific enolase for small cell carcinoma of lung. None of these new markers are specific for cancer. Furthermore, none are organ specific, except prostate specific antigen for prostatic tissue. The main application of these markers is in monitoring patients with the specific malignancies indicated. Whether routine use of any of these new markers leads to higher quality of life or enhanced survival remains to be determined.

Auto-antibodies in chronic active hepatitis may bind to cancer antigens

Auto-antibodies in auto-immune chronic active hepatitis (AICAH) are hypothesized to bind to cancer antigens.

The pathologist and the clinical oncologist: a new effective partnership in assessing tumor prognosis

During the past 20 years, we have witnessed a progressive radical change in the role of the pathologist vis à vis several aspects of clinical oncology. From the traditional description by light microscopy of resected specimens and study of tumor classifications, the modern pathologist has expanded his domain of action which now results in deeper and more effective interactions with the surgeon, radiotherapist and medical oncologist. The wide application of fine-needle biopsy has substantially improved early diagnosis of primary neoplasms and local and distant recurrences. The histogenetic classification based on type of tissue formed by the tumor rather than type of tissue from which tumor arises, the results of pathologic staging as well as the degree of tumor cell necrosis following primary chemotherapy are now being correlated with treatment outcome. The assessment of tumor grade and ploidy can allow more accurate selection of patient subgroups at high risk of early relapse. Last but not least, the morphologic recognition of certain types of iatrogenic morbidity helps in the reassessment of given drug combinations. During the past decade, pathologists have contributed to the development of several new investigative techniques whose first applications, in most instances, were in laboratories dedicated to basic research. More recently, some pathologists have begun to explore the feasibility of applying these same techniques to clinical cancer research. Modern sophisticated technology, including flow cytometry, immunohistochemistry and monoclonal antibodies, can now provide research physicians with important prognostic indicators such as tumor cell proliferative activity, steroid receptor status, occult distant micrometastases, immunologic phenotypes and gene amplification. By fulfilling several new tasks, which have contributed to the knowledge of the natural history of many tumors, the pathologist has become an integral part of the team planning new treatment strategies and evaluating their final outcome.