Modification of invasion and differentiation in human melanoma cell clones.

In an attempt to define the role of plasminogen activator in invasiveness and differentiation of human melanoma cells, the modulation of these parameters was studied in two melanoma clones characterized by marked differences in their basal features, using 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and retinoic acid, two differentiation inducers, and doxorubicin, a cytotoxic agent. TPA induced only slight reductions, whereas retinoic acid and doxorubicin caused an increase in invasiveness, enzymatic activity and differentiation in the clone showing low invasivity, low urokinase-type plasminogen activator levels and high differentiation. In contrast, in the clone showing high invasivity, high urokinase-type plasminogen activator levels and low differentiation it was found that: TPA was ineffective; retinoic acid induced a reduction of plasminogen activator but no modifications of invasiveness and differentiation; doxorubicin caused a decrease in invasiveness and plasminogen activator activity but no modification of morphological features. The different behaviour of the two clones thus could be related to the basal features of the clones. The results reported here indicate that in the presence of these drugs the associations between invasiveness and urokinase-type plasminogen activator activity and between invasiveness and differentiation are lost. Drug treatment therefore significantly affected the features of the clone characterized by low biological aggressiveness (high differentiation, low invasiveness), whereas the highly aggressive clone did not show a consistent response to drug treatment.

Relationship between the levels of purine salvage pathway enzymes and clinical/biological aggressiveness of human colon carcinoma.

A large series of samples obtained after surgical resection of intestinal mucosa of patients affected by intestinal carcinoma was examined in order to define possible relationships between levels of enzymes involved in the purine salvage pathway and clinical/biological parameters of aggressiveness and invasiveness. The results confirm our previous observation on a different pattern of purine salvage enzymes in tumor as compared to normal colon tissues (Camici et al., 1990). In fact, we observed in human colon tumor tissues a significant enhancement of the three enzymes involved in the synthesis of IMP, hypoxanthine guanine phosphoribosyltransferase (HGPRT), adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP). On the other hand, no variation was observed in the 5'-nucleotidase and alkaline phosphatase activities. While we could not find a significant correlation between HGPRT, ADA and PNP activities and histologic grading or biological parameters of tumor aggressiveness, the significant correlation with the extent of disease, as expressed by the Dukes' stage, would demonstrate at least for human colon tumors, a relationship between enzyme activity and tumor invasiveness.

Biological and enzymatic features of human melanoma clones with different invasive potential.

Cell clones derived from a human melanoma metastasis selected for different integrin profiles were examined in vitro for invasive potential and biological and biochemical features potentially related to this process. Clones which expressed high levels of integrins showed high invasive potential, extracellular matrix degradation, and adhesion to gelatin-coated substrates. A correlation was also found between invasiveness and intracellular and extracellular plasminogen activator activity. Heparanase and collagenase type IV activities were apparently unrelated to invasiveness. gamma-Glutamyl transferase (GGT) activity was high in highly invasive clones, whereas melanin content was high in slightly invasive clones. Heterogeneity was also observed in cellular parameters such as cell dimensions, growth features and DNA index. The intrinsic biological and biochemical heterogeneity of a cell population derived from a single metastasis may be responsible for the different behaviour of clones, regardless of their invasive potential. Since slightly invasive cells are more differentiated than highly invasive cells, malignancy and differentiation are inversely correlated in such human melanoma clones.

Activity of a chartreusin analog, elsamicin A, on breast cancer cells.

The in vitro activity of elsamicin A (ELS) was investigated compared with that of doxorubicin (DX) on two sensitive breast cancer cell lines: one estrogen receptor-positive (ER+, MCF7) and one estrogen receptor-negative (ER-, MDA-MB-231) line, and on a DX-resistant subline (MCF7DX). The activity of the two drugs was also investigated on 19 clinical breast cancer specimens from untreated patients. The drugs were tested at pharamcologically relevant concentrations, as calculated from the area under the curve for a 3 h exposure to the lethal dose producing 10% mortality (LD10) in mice, and at 10- and 100-fold concentrations. In DX-sensitive lines, a greater inhibition of RNA and DNA precursor incorporation, as well as of cell proliferation, was caused by ELS than by DX. Moreover, the antiproliferative effect was 10-fold higher in the ER+ MCF7 than in the ER- MDA-MB-231 cell line (IC50: 0.25 versus 0.21 micrograms/ml). ELS was cross-resistant to DX in the MCF7DX subline. In clinical specimens, effects on DNA precursor incorporation were more often observed for ELS than for DX at the same drug concentrations. The in vitro sensitivity to ELS was more pronounced for ER+ than for ER- tumors: minimal inhibiting concentrations of the drug were 0.1 and 3.5 micrograms/ml, respectively, in the two groups. If confirmed in a larger series of human breast tumors, these in vitro results would indicate a promising role for ELS in clinical treatment, mainly of ER+ breast cancer patients.

Expression of P-glycoprotein in breast cancer tissue and in vitro resistance to doxorubicin and vincristine.

Expression of P-glycoprotein was evaluated by C219 monoclonal antibody immunoblots in 34 previously untreated and 14 pretreated breast cancers and in benign breast lesions or histologically normal breast glands. P-glycoprotein was not detectable in the few cases of normal or benign tissue. P-glycoprotein was expressed in the 170 kD areas of 29% (10/34) of untreated and 64% (9/14) of previously treated tumours (P = 0.02). In treated tumours, high intensity expression was observed more frequently than in untreated breast cancer (40% vs. 9%). Moreover, there was a significant association between P-glycoprotein expression and in vitro resistance to doxorubicin and vincristine. Simultaneous resistance was observed in all of the P-glycoprotein positive and in only 56% of the P-glycoprotein negative tissues (P less than 0.01). Some aspects of the typical multidrug resistant phenotype, such as P-glycoprotein expression and simultaneous resistance to doxorubicin and vincristine, could be detected in small subsets of breast cancer patients. No relation between P-glycoprotein expression and the type of previous clinical treatment was observed.

Cytotoxic activity of azelaic acid against human melanoma primary cultures and established cell lines.

The in vitro cytotoxic activity of azelaic acid was studied with 25 human melanoma primary cultures and with 5 established cell lines characterized by different contents of melanotic pigment. A dose-dependent antiproliferative effect was observed in both the experimental systems, even though cell lines displayed a slightly greater susceptibility to the compound, with ID50 values generally lower than those for fresh human tumors. Our results do not demonstrate a clear difference between melanotic and non-melanotic melanomas in sensitivity to azelaic acid. The early interference of azelaic acid on nucleic acid metabolism was investigated additionally with 15 human melanoma primary cultures. There were significant inhibitions of RNA and DNA synthesis in a remarkable percentage of tumors, at the highest concentrations of the compound. Moreover, cell proliferation of tumors that showed these antimetabolic effects was always significantly depressed by lower drug concentration as well as by the highest.

Purine salvage enzyme activities in normal and neoplastic human tissues.

The enzymatic pattern of five enzymes involved in the purine salvage pathway, namely purine nucleoside phosphorylase (EC 2.4.2.1), adenosine deaminase (EC 3.5.4.4), 5'-nucleotidase (EC 3.1.3.5), alkaline phosphatase (EC 3.1.3.1), and hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) has been evaluated both in human intestinal and breast carcinomas and compared to that of normal tissues. A higher level of hypoxanthine-guanine phosphoribosyltransferase was associated with tumor tissues. This metabolic alteration should lead to an elevated synthesis of nucleotides in cancer cells, might confer selective growth advantages to neoplastic tissues, and account, at least in part, for the difficulties encountered in the chemotherapy of human tumors, by using compounds affecting only the purine de novo biosynthesis.

In vitro activity of 4'-iodo-4'-deoxydoxorubicin on human colo-rectal cancer as measured by a short-term antimetabolic assay.

A short-term antimetabolic assay based upon the inhibition of incorporation of nucleic acid precursors was used to compare the cytotoxicity of a new halogenated anthracycline, 4'-iodo-4'-deoxydoxorubicin (IDX), with that of its parent compound doxorubicin (DX) on human colo-rectal carcinoma specimens. IDX showed a marked dose-dependent effect, with frequencies of activity consistently greater than those of DX at all concentrations. The minimal dose required to induce a significant antimetabolic effect for IDX was 1/10 that for DX.

Absolute and relative activities of 4' -iodo-4'-deoxydoxorubicin against human colo-rectal tumors, as evaluated by a short-term in vitro assay.

A short-term antimetabolic assay based on the interference with 3H-thymidine and 3H-uridine incorporation after 3 hours of in vitro treatment was used to compare the cytotoxicity of a new halogenated anthracycline, 4'-Iodo-4'-deoxydoxorubicin (IDX), with that of its parent compound Doxorubicin (DX) against 44 human colorectal carcinomas. IDX had a marked dose-dependent effect, with frequencies of activity consistently greater than those of DX at all concentrations. The minimal dose of IDX required to induce a significant antimetabolic effect obtained by extrapolation from the dose-effect plots for each drug was 1/10 that of DX (2.3 micrograms/ml vs 23 micrograms/ml). When the relative activities of the two drugs on the same tumor specimen were determined, there was 71% to 86% overall agreement, depending on the concentration used. Lack of agreement was always attributed to sensitivity to IDX and resistance to the parent compound.

Detection of the 170 kDa P-glycoprotein in neoplastic and normal tissues.

A membrane purification procedure and an immunoblotting assay have been designed to allow screening of human solid tumors for overexpression of the GP170 glycoprotein without employing a disaggregation method to obtain cell suspensions. The electrophoresed membrane proteins were probed, after Western Blotting, with the C219 monoclonal antibody and iodinated Protein A. The labeling intensity of the bands on the autoradioimmunoblots were quantified by densitometry. To test for the presence of GP170, we used membranes from the UV 2237 fibrosarcoma line and its adriamycin-resistant variant ADMR, grown in vitro or as solid tumor in mice. Membranes of human normal and tumor tissues obtained from previously untreated patients were also tested. An immunoreaction was observed in the adriamycin-resistant UV 2237 lines grown in vitro or in vivo. Quantitatively, the binding of the resistant cell line grown in vitro was higher than that observed in cells grown in mice. Bands in the GP 170 region were observed in 4/7 normal and in 7/7 tumor colon tissues and in the normal medulla from 2 patients with cancer of the renal cortex. No reaction could be found in samples from normal tissue, primary tumor or nodal metastasis from 7 patients with breast cancer.

Relation of in vitro drug activity to clinical response in a prospective trial for advanced germ cell testicular tumors.

An in vitro assay, which evaluates the effect of drugs on labelled DNA precursor incorporation into fresh specimens after 3 h of in vitro treatment, was used for a prospective study. Drugs were used as monochemotherapy or in different combinations according to their in vitro activities for salvage or palliation treatment of 16 patients with germ cell testicular tumors, for a total of 21 correlations between in vitro and clinical results. In 11 instances, drugs active in vitro were used; in 10 instances, because no drug was active in vitro, patients were treated with inactive drugs. There was a significant correlation between in vitro and clinical activity (p = 0.02), with a very high true-negative rate (90%) and a lower true-positive rate (54%). No patient treated with drugs inactive in vitro survived 2 years, whereas freedom from progression and overall survival for patients treated with drugs active in vitro were 27.3 and 36.4%, respectively (active vs. inactive, p = 0.007). The overall response in the group of patients treated prospectively was comparable to that observed in a group of 9 patients treated in the same period of time with drugs of unknown in vitro activity (33 vs. 11% objective and long-term responses, respectively, p = n.s.) notwithstanding the high percentage of patients treated with drugs inactive in vitro in the former group.

Drug sensitivity of different tumor lesions from the same patient evaluated by a short-term assay.

A short-term antimetabolic assay, which considers the interference with [3H]thymidine incorporation as an indicator of drug effect, has been used to comparatively assess the chemosensitivity of different tumor lesions from the same patient. The analysis was performed on primary tumors and their synchronous metastases from 67 patients with breast, ovarian, gastrointestinal and germ cell testicular tumors. A remarkable difference in sensitivity to cytostatic drugs was observed between the two lesions. In contrast, a strong association in chemosensitivity (81.7% agreement rate; p less than 0.01) was observed between two synchronous metastases from 17 patients with breast, ovarian, germ cell testicular tumors or malignant melanoma. In addition, the predictive relevance of the antimetabolic assay on clinical response to chemotherapy was analyzed in relation to the type of tumor lesion tested in vitro in a retrospective correlative study on 57 patients with advanced ovarian and germ cell testicular tumors. The objective clinical response was significantly correlated to the in vitro sensitivity of metastases (83.7% agreement rate; p less than 0.01), but not to that of the primary tumor.

Application of an in vitro antimetabolic assay to human germ cell testicular tumors for the preclinical evaluation of drug sensitivity.

An in vitro assay, which evaluates the effect of drugs on labeled nucleotide precursor incorporation 3H-thymidine and 3H-uridine after 3 hours of in vitro treatment, was applied to human germ cell testicular tumors. The assay was feasible on 78% of the 259 tumors, and the results were evaluable in 95% of these, which shows the good potential of its clinical application. In vitro response rates to conventional agents were comparable to clinical response rates reported in the literature for monochemotherapy regimens, thus demonstrating the accuracy of the assay in reproducing the sensitivity of the tumor type. The specificity of the assay in predicting drug sensitivity of individual tumors was investigated on 28 lesions from 24 patients who had residual disease after surgery. A significant correlation was found between in vitro and clinical sensitivity to the same drugs (P = 0.026), with an overall agreement of 92% when tumor metastases were tested in vitro. In contrast, no significant correlation, and a poor agreement (62%) was found when the primary tumor was tested.

In vitro activity of alkylating agents on human tumors as measured by a short-term antimetabolic assay.

The activity of some alkylating agents widely used in clinical practice was studied by an in vitro antimetabolic assay, which evaluates the interference of drugs on the incorporation of 3H-thymidine and 3H-uridine in short-term cultures of human tumors. The effect of CCNU, chlorambucil, cisplatin, melphalan, prednimustine, procarbazine and the pro-active derivatives of cyclophosphamide and ifosfamide, 4-hydroperoxycyclophosphamide and 4-hydroperoxyifosfamide, was tested on non-Hodgkin lymphomas, germ cell testicular tumors, breast and ovarian cancers. Similar effects were generally produced by the drugs on both DNA and RNA precursor incorporation, and the in vitro response rates were similar to those clinically obtained for the same tumor types by using the same drugs in monochemotherapy. The effects of different alkylating agents on the individual tumors were not significantly associated, except for the analogues 4-hydroperoxycyclophosphamide and 4-hydroperoxyifosfamide, for which a significant agreement rate was observed. No evidence of acquired resistance to 4-hydroperoxycyclophosphamide and cisplatin after clinical treatment with the same drug was found in samples from ovarian cancer and non-Hodgkin lymphoma, but there was a definite trend in germ cell testicular tumors to lower sensitivity to cisplatin in previously treated patients.

Reliability of an in vitro short-term assay to predict the drug sensitivity of human breast cancer.

The feasibility and reliability of an in vitro assay that evaluates drug interference on nucleic acid precursor incorporation were investigated on 135 previously untreated locally advanced breast cancers. The assay, which was carried out on tumor fragments incubated for 3 hours with drugs, proved to be feasible on a sufficiently high percentage of biopsy specimens (70%) for routine clinical use. In vitro drug activity evaluated with this assay appeared to reproduce the clinical patterns of sensitivity of the tumor type as well as of the individual tumors. In fact, in vitro response rates to conventional agents resembled the clinical response rates reported for the same agents used in monochemotherapy. From a retrospective--correlative study carried out on 41 patients treated in vitro and in vivo with the same drugs (Adriamycin [doxorubicin] and vincristine), in vitro effect of Adriamycin on 3H-uridine incorporation appeared significantly correlated with clinical response (overall agreement, 78%; P = 0.0032) with specific agreements of sensitivity and resistance of 75% and 81%, respectively.

Cell proliferation and its relationship to clinical features and relapse in breast cancers.

The relationship between primary tumor proliferative activity and clinical and pathologic characteristics was analyzed in relation to menopausal status for 541 breast cancer patients. The thymidine-3H labeling index (LI) showed significantly higher median values in cancers from premenopausal (4.2%) and paramenopausal (4.2%) patients in comparison to that of cancers from postmenopausal (1.8%) patients. The LI was not generally correlated to tumor size. The only significant correlation was limited to tumors with negative axillary lymph nodes from premenopausal patients. The proliferative activity of primary tumors was neither correlated to the presence nor the extension of axillary metastasis. The prognostic significance of the primary tumor LI was assessed in 145 untreated patients with cancers without axillary metastases. A higher median value of LI was observed in tumors from patients who relapsed (5.7%) within 52 months than in tumors from those who did not relapse (2%). However, the difference was statistically significant (P less than 0.01) in premenopausal patients, but not in postmenopausal patients. Similarly, a significantly (P less than 0.0005) higher rate of relapse (67.4%) was observed in patients with tumors that had a LI above the median value of 4.6% in comparison to that (0%) of tumors with a LI below the median value in premenopausal patients. No statistically significant relationship was observed between proliferative activity of the primary tumor and risk of relapse in postmenopausal patients.