Modulation of tumour marker CA-125 expression in cultured ovarian carcinoma cells

How to Overcome the Disturbing Effects of Human Anti-Mouse Antibodies (Hama) on in Vitro Assays

The development of human anti-mouse antibodies (HAMA) is a common immune response in patients with ovarian carcinoma after repeated injections of murine anti-CA 125 monoclonal antibodies for immunoscintigraphy. As a tumor marker with significant diagnostic value CA 125 is routinely measured in the follow-up of tumor patients by immunoradiometric assays (IRMA) based on murine anti-CA 125 monoclonal antibodies. HAMA may cause false-positive findings in a CA 125-IRMA. In this report our group demonstrates a simple way of eliminating HAMA by protein A/G affinity chromatography allowing the reliable detection of the tumor marker CA 125 in the serum of patients with ovarian carcinoma.

Regulation of CA 125 Expression in Cultured Human Carcinoma Cells

CA 125 shedding is not a constitutive and stable process but may be affected by cell cycle and cell proliferation as well as by various growth factors and cytokines. Interferons, interleukin-1β, tumor necrosis factor-α and transforming growth factor-α have been shown to induce while glucocorticoids and transforming growth factor-β have been shown to suppress the release of the tumor marker CA 125 from ovarian carcinoma cells. Several endogenous as well as exogenous factors may affect CA 125 biosynthesis; however, a major question remains whether this observed modulation of CA 125 expression in vitro is of clinical importance.

The impact of enzastaurin (LY317615.HCl) on CA125 biosynthesis and shedding in ovarian cancer cells

BACKGROUND

In this study the modulatory effect of the proteinase kinase C beta (PKC beta) selective inhibitor enzastaurin on CA125 expression and shedding in ovarian cancer cells (OVCAR-3 cells) was investigated. MATERIAL ANDMETHODS: OVCAR-3 cells were cultured in vitro and treated with increasing concentrations of carboplatin (2-1000 microM), paclitaxel (0.2-100 nM) or enzastaurin (1-100 microM) single agent. Growth inhibitory effects were evaluated by MTS and luminescence assay. CA 125 was determined in supernatans and in cell lysate using an electrochemo-iluminescence immunoassay.

RESULTS

Cell growth of OVCAR-3 cells was inhibited by single agent carboplatin, paclitaxel or enzastaurin in a dose dependent manner. Carboplatin caused a transient increase of CA125 in supernatans followed by a gradual decrease of CA125. Treatment with increasing doses of paclitaxel or enzastaurin caused an increase of CA125 shedding in culture medium but also the membrane bound fraction of CA125 was increased.

CONCLUSION

These results suggest that enzastaurin, as paclitaxel, has a direct stimulatory effect on CA 125 synthesis and shedding in vitro.

Ovarian cancer pathogenesis: a model in evolution

Ovarian cancer is a deadly disease for which there is no effective means of early detection. Ovarian carcinomas comprise a diverse group of neoplasms, exhibiting a wide range of morphological characteristics, clinical manifestations, genetic alterations, and tumor behaviors. This high degree of heterogeneity presents a major clinical challenge in both diagnosing and treating ovarian cancer. Furthermore, the early events leading to ovarian carcinoma development are poorly understood, thus complicating efforts to develop screening modalities for this disease. Here, we provide an overview of the current models of ovarian cancer pathogenesis, highlighting recent findings implicating the fallopian tube fimbria as a possible site of origin of ovarian carcinomas. The ovarian cancer model will continue to evolve as we learn more about the genetics and etiology of this disease.

Serum and tissue biomarkers as predictive and prognostic variables in epithelial ovarian cancer

Tumour stage, residual disease after initial surgery, histological type and tumour grade are the most important clinical-pathological factors related to the clinical outcome of patients with epithelial ovarian cancer. In the last years, several investigations have assessed different biological variables in sera and in tissue samples from patients with this malignancy in order to detect biomarkers able to reflect either the response to chemotherapy or survival. The present paper reviewed the literature data about the predictive or prognostic relevance of serum CA 125, soluble cytokeratin fragments, serum human kallikreins, serum cytokines, serum vascular endothelial growth factor and plasma d-dimer as well as of tissue expression of cell cycle- and apoptosis-regulatory proteins, human telomerase reverse transcriptase, membrane tyrosine kinase receptors and matrix metalloproteinases. A next future microarray technology will hopefully offer interesting perspectives of translational research for the identification of novel predictive and prognostic biomarkers for epithelial ovarian cancer.

Modulation of CA-125 tumor marker shedding in ovarian cancer cells by erlotinib or cetuximab

OBJECTIVE

The EGF receptor tyrosine kinase inhibitor erlotinib and the EGF receptor antibody cetuximab were investigated with respect to their antiproliferative effect in vitro and their influence on the synthesis and secretion of the tumor marker CA-125 in ovarian carcinoma and human peritoneal mesothelial (HPMC) cells.

METHODS

Ovarian cancer cell lines and HPMC were cultured in vitro under the usual conditions. CA-125 surface expression was detected by a living cell radio-immunoassay. CA-125 concentration shed into supernatant medium was determined using a microparticle enzyme immunoassay.

RESULTS

Proliferation was inhibited by erlotinib in a dose-dependent manner in 4/5 cell lines but in none of the HPMCs. Only the erlotinib-sensitive cell lines also responded by decreasing surface density of CA-125. Release of CA-125 into the supernatant medium was independent of its surface density and was increased by erlotinib treatment in all but HTB77 cancer cells but not in HPMCs. Very similar results were obtained when the EGFR antibody cetuximab was used in place of erlotinib.

CONCLUSION

The results indicate that the effects observed were a consequence of EGFR inhibition. The influence exerted by erlotinib or cetuximab treatment on shedding and cell surface density of CA-125 leads us to conclude that CA-125 blood levels measured during therapy might not correctly indicate changes in tumor size.

The predictive and prognostic value of serum CA 125 half-life during paclitaxel/platinum-based chemotherapy in patients with advanced ovarian carcinoma

OBJECTIVES

Serum CA 125 kinetics during early chemotherapy has a strong predictive and prognostic relevance for patients with advanced ovarian carcinoma who received a first-line platinum-based regimen, whereas the ability of serum CA 125 assay to reflect the response to paclitaxel-based chemotherapy has not yet been defined. The aim of the present paper is to calculate the serum CA 125 half-life during first-line paclitaxel/platinum-based chemotherapy in patients with advanced ovarian carcinoma and to correlate this kinetic parameter with the response to treatment, progression-free survival and overall survival.

METHODS

This retrospective investigation assessed 71 patients with stages IIc-IV ovarian carcinoma who underwent initial surgery followed by paclitaxel/platinum-based chemotherapy and who had serum CA 125 > 35 U/ml before the first cycle of chemotherapy. Only epithelial ovarian cancers were included.

RESULTS

The 25%, 50%, and 75% quantiles of serum CA 125 half-life during early chemotherapy were 10, 14, and 20 days, respectively. Taking the value corresponding to the 50% quantile (i.e., 14 days) as cutoff limit, serum CA 125 half-life was an independent prognostic factor for the chance of achieving a complete response to treatment as well as for progression-free survival and overall survival. In detail, patients with serum antigen half-life <== 14 days had a 3.362 times as great probability to achieve a complete response and a 3.113 times as low probability to die when compared to those with a longer half-life.

CONCLUSIONS

Serum CA 125 assay represents a reliable biochemical tool for the management of advanced ovarian carcinoma patients who receive a first-line paclitaxel/platinum-based chemotherapy.

The CA125 regression rate to predict overall survival differ between paclitaxel-containing regimen and nonpaclitaxel regimen in patients with advanced ovarian cancer

In this study, we compare the time to normalization of CA125 after cytoreductive surgery between a paclitaxel-containing regimen and a non-paclitaxel regimen. This study demonstrates that CA125 regression in a paclitaxel-containing regimen was slower than that in a non-paclitaxel regimen. When we determine the CA125 regression rate to predict overall survival in ovarian cancer, we should take into account the kind of chemotherapy regimen, especially the use of paclitaxel.

Assessment of CA 15.3, CEA and TPA concentrations during monitoring of breast cancer

The variability of the tumor markers cancer antigen (CA) 15.3, carcinoembryonic antigen (CEA) and tissue polypeptide antigen (TPA) during steady state concentrations and the rate of increase during progression is described. One hundred and ninety-two patients were monitored during first-line chemotherapy for metastatic breast cancer and during follow-up. Blood specimens were sampled approximately every four weeks. Steady state concentrations were registered for 77 (CA 15.3), 96 (CEA), and 127 (TPA) patients with below cutoff level values and for 28 (CA 15.3), 25 (CEA), and 11 (TPA) patients with above cutoff level values. Clinical and marker progression was registered for 75 (CA 15.3), 62 (CEA), and 57 (TPA) patients. The coefficients of total variation of steady state concentrations (comprising the intra- and interassay analytical imprecision and the within subject biological variation) were higher below (14.9% CA 15.3, 15.4% CEA, 25.9% TPA) than above cutoffs (9.6% CA 15.3,6.0% CEA, 19.9% TPA). The variability was similar for CA 15.3 and CEA but higher for TPA. During progression the rates of increase in concentrations were similar for CA 15.3 (0.0257) and CEA (0.0214) and lower than for TPA (0.0346). Our data indicate that criteria for assessment of sequential tumor marker concentrations should consider the marker in question, the steady state variability, the cutoff value, and the rate of increase during disease progression.

Effects of paclitaxel on CA-125 serum levels in ovarian cancer patients

OBJECTIVE

As in vitro activation of ovarian carcinoma cells in terms of CA-125 secretion by taxanes has been demonstrated, we were interested in whether taxanes also modulate CA-125 expression in vivo.

METHODS

Serum CA-125 was determined immediately before and 24 h after paclitaxel-containing chemotherapy in 53 ovarian carcinoma patients. To test the quality of the analysis methods and the biological variation of untreated patients, serum CA-125 levels of two control groups were analyzed.

RESULTS

Median CA-125 concentration was 107 kU/liter 24 h after chemotherapy treatment compared with 99 kU/liter the day before paclitaxel treatment. Changes in CA-125 serum levels observed immediately after paclitaxel treatment were not correlated to treatment response. However, overall change in CA-125 serum concentration was a good predictor of response to paclitaxel containing treatment. Patients achieving a complete or partial response had a significant reduction of median CA-125 levels, whereas tumor progression was associated with increased CA-125 levels. Only for the group of patients obtaining a complete response was a decrease in the median relative CA-125 value observed.

CONCLUSION

Paclitaxel-induced modulation of CA-125 expression could not be confirmed in vivo.

Carcino-embryonic antigen in monitoring the growth of human colon adenocarcinoma tumour cells SK-CO-1 and HT-29 in vitro and in nude mice

A set of experimental model systems were designed to investigate (a) the inter-relationship between growth of two human cancer cell lines (SK-CO-1, HT-29) and carcino-embryonic antigen (CEA) kinetics; and (b) whether neoplastic growth or CEA concentration is modulated by human growth hormone (hGH). We found that increasing CEA concentration depended on tumour burden. SK-CO-1 cells had the lowest growth rates but the highest rates of CEA production. The rate of CEA increase exceeded the growth rate of both SK-CO-1 and HT-29. hGH modulated neither neoplastic growth nor CEA production. In conclusion, our results suggest that experimental models may be useful for investigating the role of serological markers as monitors of increasing tumour burden. It will be of interest to investigate the performance of those model systems in examining the effect of cytotoxic agents in neoplastic growth.

Generation of Human Monoclonal Anti-idiotypic Antibodies with Specificity to the Murine Monoclonal Anti-CA 125 Antibody B43.13

Two human monoclonal antibodies, HID-7E7 and ROB-6F2, were produced by EBV transformation of peripheral blood lymphocytes (PBL). PBL were obtained from a patient with ovarian cancer who had been exposed several times to a Tc-99m labeled murine monoclonal anti-CA 125 antibody (B43.13, Biomira, Edmonton) for immunoscintigraphy. The HID-7E7 and ROB-6F2 producing B-cells were cloned with a limiting dilution technique and have shown stable immunoglobulin secretion within a period of three years. The human monoclonal antibodies HID-7E7 and ROB-6F2 are of the IgG isotype, and bind with significant affinity to the murine monoclonal antibody B43.13, which was used for immunoscintigraphy. Binding affinity of ROB-6F2 to other murine antibodies could not be detected. Cross reactivity of HID-7E7 to a murine anti-CEA monoclonal antibody was observed. In order to verify the anti-idiotypic character of the generated human antibodies, the ability of HID-7E7 and ROB-6F2, respectively, to inhibit the formation of the CA125/B43.13 complex is demonstrated via an enzyme-linked immunosorbent assay. These human anti-idiotypic antibodies are possible candidates for immunotherapy of ovarian cancer in patients with a small tumor burden following surgery and/or chemotherapy.

Prognostic significance of serum CA 125 antigen assay in patients with non-small cell lung cancer

BACKGROUND

The serum levels of CA 125 tumor-associated antigen in patients with lung cancer have been previously related to TNM stage, histologic type, and survival rate. In the current study, the prognostic information provided by the CA 125 antigen assay was analyzed.

METHODS

Preoperative serum of CA 125 antigen was determined in 137 patients with non-small cell lung cancer. The assay was performed by means of a solid-phase enzyme-immunoassay test. The influence of CA 125 serum level on postoperative outcome was studied by a multivariate analysis, performed with Cox's proportional hazards regression model.

RESULTS

Patients whose initial CA 125 level was higher than 15 U/ml had a 3.25-fold greater likelihood of relapse (95% confidence interval [CI], 1.7-6.21) (P < 0.001) and a 4.27-fold greater likelihood of deaths (95% CI, 2.42-7.55) (P < 0.001) due to cancer than patients with lower values. For patients with serum levels over 15 U/ml, the 36-month survival rate posttreatment was lower (67% versus 20%) (P < 0.001), as was the disease-free rate (64% versus 13%) (P < 0.001). After adjustment for TNM stages, histologic type, sex, and age, patients with CA 125 values over 15 U/ml continued exhibiting higher risk of relapse (hazard ratio, 2.2; 95% CI, 1.04-4.69) (P = 0.04) and higher risk of death (hazard ratio, 2.42; 95% CI, 1.29-4.54) (P = 0.006).

CONCLUSIONS

CA 125 is an independent prognostic factor of survival and tumor relapse in non-small cell lung cancer. The preoperative serum level of CA 125 antigen is inversely correlated with the outcome figures. The authors suggest that CA 125 be included in any future multifactorial analysis of survival.