Oncogenes as clinical prognostic indicators

Efficacy of lower dose capecitabine in patients with metastatic breast cancer and factors influencing therapeutic response and outcome

OBJECTIVE

Capecitabine exerts considerable therapeutic efficacy in metastatic breast cancer (MBC) patients previously treated with anthracyclines and taxanes.

MATERIALS AND METHODS

In this study, the efficacy and safety of lower dose capecitabine (2000 mg/m(2)/d) in patients with anthracycline- and taxane-pretreated MBC were studied with a special emphasis on the potential predictors of time to tumor progression (TTP) and response to the capecitabine treatment.

RESULTS

The overall response rate (ORR) was 17%. The median TTP was 5 months. Among various factors analyzed, univariate analysis showed that a performance status (PS) of 2 and the presence of visceral metastases were inversely correlated with TTP. Multivariate analysis showed that a poor PS score was associated with impaired TTP.

CONCLUSIONS

Our study indicates that lower dose capecitabine has substantial antitumor activity and a favorable safety profile in the treatment of anthracycline- and taxane-pretreated MBC. Also, only performance score was demonstrated to be a significant parameter affecting TTP.

Overexpression of the Colony-Stimulating Factor (CSF-1) and/or Its Receptor c-fms in Mammary Glands of Transgenic Mice Results in Hyperplasia and Tumor Formation

A number of recent studies have suggested that the colony-stimulating factor (CSF-1) and its receptor c-fms may be involved in the development of mammary glands during lactation and breast cancer. To study the role of CSF-1 or its receptor in initiation of mammary tumorigenesis, we have generated two independent lines of transgenic mice that overexpress either CSF-1 or c-fms under the control of the mouse mammary tumor virus promoter. Mammary glands of the virgin CSF-1 transgenic mice show increased ductal branching, hyperplasia, dysplasia, and other preneoplastic changes, which are indicative of increased cellular proliferation. Similar changes were also evident in the mammary glands of the c-fms transgenic mice. These changes became more prominent with age and resulted in mammary tumor formation. Moreover, secondary events like dimethylbenz(a)anthracene treatment accelerated mammary tumor formation in these mice. Although the expression of estrogen receptor alpha was not significantly changed in either of the transgenic mouse strains, progesterone receptor levels was higher in both transgenic lines as compared with the nontransgenic littermates. Expression of G1 cyclins was prominently increased in the mammary glands of both the CSF-1 and c-fms transgenic lines, suggesting increased cell cycle progression in these strains. In addition, the proliferation marker proliferating cell nuclear antigen (PCNA) and the mitogen-responsive transcription factor c-jun were also increased as compared with the nontransgenic controls. These findings, along with the histological data, support the hypothesis that CSF-1 and its receptor are involved in the etiology of breast cancer.

Estrogen promotes growth of human thyroid tumor cells by different molecular mechanisms

Thyroid tumors are about 3 times more frequent in females than in males. Epidemiological studies suggest that the use of estrogens may contribute to the pathogenesis of thyroid tumors. In a very recent study a direct growth stimulatory effect of 17beta-estradiol was demonstrated in FRTL-5 rat thyroid cells. In this work the presence of estrogen receptors alpha and beta in thyroid cells derived from human goiter nodules and in human thyroid carcinoma cell line HTC-TSHr was demonstrated. There was no difference between the expression levels of estrogen receptor alpha in males and females, but there was a significant increase in expression levels in response to 17beta-estradiol. Stimulation of benign and malignant thyroid cells with 17beta-estradiol resulted in an increased proliferation rate and an enhanced expression of cyclin D1 protein, which plays a key role in the regulation of G(1)/S transition in the cell cycle. In malignant tumor cells maximal cyclin D1 expression was observed after 3 h, whereas in benign cells the effect of 17beta-estradiol was delayed. ICI 182780, a pure estrogen antagonist, prevented the effects of 17beta-estradiol. In addition, 17beta-estradiol was found to modulate activation of mitogen-activated protein (MAP) kinase, whose activity is mainly regulated by growth factors in thyroid carcinoma cells. In response to 17beta-estradiol, both MAP kinase isozymes, extracellular signal-regulated protein kinases 1 and 2, were strongly phosphorylated in benign and malignant thyroid cells. Treatment of the cells with 17beta-estradiol and MAP kinase kinase 1 inhibitor, PD 098059, prevented the accumulation of cyclin D1 and estrogen-mediated mitogenesis. Our data indicate that 17beta-estradiol is a potent mitogen for benign and malignant thyroid tumor cells and that it exerts a growth-promoting effect not only by binding to nuclear estrogen receptors, but also by activation of the MAP kinase pathway.

The 1999 James Ewing Lecture: in pursuit of molecules of oncogenesis and neoplastic therapy

Breast cancer is a progressive, phenotypic, genetic and epigenetic alteration, induced by various stimulants of which the principal steroid hormone, estrogen, initiates and promotes neoplastic transformation of normal ductal mammary epithelium to acquire distinct biochemical and molecular characteristics. The molecular events that characterize oncogenesis with dysregulated physiologic states represent an area of intense translational research. The progress of the last century suggests that the targeted responses initiated by this steroid hormone can be attenuated and modified with anti-estrogen therapies or through applied intervention with selective estrogen receptor modulation. New pharmacological, genetic, and biological agents will undoubtedly afford clinical investigators of the next millennium the opportunity to provide major impact on the disease progression of this neoplasm, through these targeted endocrine responses for estrogen.

A 27 kDa heat shock protein that has anomalous prognostic powers in early and advanced breast cancer

This paper describes a prospective immunohistochemical analysis of 27 kDa heat shock protein (HSP27) in 361 patients with primary breast cancer in relation to disease-free survival (DFS) and survival from first relapse (SR). Oestradiol (ER) and progesterone (PR) receptors were also quantitated and related to the HSP27 data. While ER positively predicted a good outcome for both DFS and SR, HSP27 positivity predicted a prolonged SR but short DFS. The association between HSP27 and DFS only attained statistical significance in node-negative patients. Subgroup analysis reinforced the complementary relationship of HSP27 and ER for SR and opposing influences for DFS. In both node-negative and node-positive women, ER+ HSP27- patients had a longer DFS than ER- HSP27+ counterparts. There was no relationship between HSP27 and overall survival. HSP27 staining was highly correlated with ER but not PR, patient age, tumour size or menstrual status. There was a marginal correlation (P = 0.04) with histological grade with well-differentiated tumours having the highest HSP27. Cox multivariate regression analysis of the contribution of HSP27 in the presence of data on ER, PR, stage, nodal status and histological grade indicated that HSP27 was not of independent prognostic importance for DFS or overall survival and was only of borderline significance for OS (P < 0.07). However, in the absence of ER and PR data, HSP27 staining is an effective way of getting the same prognostic information. HSP27 staining appears to correlate with different biological features in early and advanced breast, high HSP27 being linked with short DFS in node-negative patients but with prolonged survival from first recurrence.

Tyrosine kinase receptor--nuclear protooncogene interactions in breast cancer

In summary, evidence is beginning to accumulate in support of a major role for tyrosine kinase receptors (and their activating growth factors) and steroid hormones and their receptors in normal development and differentiation of the mammary gland. A point of intersection of their mechanisms of action in growth control appears to be the induction of nuclear protooncogenes such as c-myc. When c-myc is amplified, as it is in many breast cancers, EGF and FGF receptor tyrosine kinase action becomes transforming, not simply mitogenic. A source of the transforming factors could be either stromal or epithelial. This mechanism could function early in the progression of breast cancer. c-erbB-2 and EGF receptor overexpression and amplification, when they occur, appear to render tumors even more malignant and of especially poor prognosis. These mechanisms could function late in the progression of breast cancer. Transgenic mouse studies have begun to echo these themes. They have established that a growth factor (TGF-alpha) and its receptor (EGF receptor), which appear to be important in normal mouse and human proliferation and gland development, and a protooncogene (c-myc), commonly amplified and overexpressed in human and mouse breast cancer, can each contribute to mammary carcinogenesis. The mechanisms of the two are likely to be distinct. myc is likely to be acting as a tumor initiator in combination with normal proliferative factors, whereas TGF-alpha is likely to be acting as a hyperproliferative (promotional) factor in combination with a normal background of mutational events. The role of unmutated but amplified erbB-2 in the transgenic mouse is not yet known.

Prognostic indicators in invasive breast cancer

Tumor size and axillary lymph node involvement are the primary determinants of clinical course for most patients. Receptors for estrogen and progesterone are important additional prognostic factors for disease-free survival, overall survival, survival time after initial disease recurrence, and the likelihood of response to hormonal therapy. Histologic grading has merit as a prognostic factor, although poor reproducibility limits its broad application. Promising data have been emerging from the use of flow cytometry to analyze DNA content and proliferative rate. Patients with aneuploid tumors are more likely to have a shorter survival time than patients with diploid tumors. A high S-phase fraction also identifies a subset of patients at increased risk for early relapse. A combined index of ploidy and S-phase may be a more useful guide; together, diploidy and low S-phase identify a subgroup of node-negative patients at very low risk for disease recurrence. A number of oncogenes have been identified in breast cancer; amplification of the HER-2/neu gene or overexpression of the gene product may be an important prognostic indicator for node-positive patients.