Natural polyamines-linked cyclophosphazenes. Attempts at the production of more selective antitumorals

Computer-assisted morphonuclear characterization of radiotherapy-induced effects in MXT mouse mammary adenocarcinomas surviving earlier radiotherapy

PURPOSE

To present the effects of different radiotherapeutic treatments on the morphonuclear characteristics and growth of the MXT mouse mammary adenocarcinoma.

METHODS AND MATERIALS

We collected MXT tumor cells by means of fine-needle aspirations during various radiotherapeutic treatments and analyzed the morphological aspects of the cell nuclei by means of the digital cell image analysis of Feulgen-stained nuclei. In addition, we studied the morphonuclear aspects of cells from MXT tumors that had been radioresistant cell enriched. These radioresistant cell-enriched tumors involved MXT tumors that had survived one or two previous radiotherapies. The radiotherapy-induced effects on the morphonuclear characteristics were monitored by means of both monovariate (one-way variance) and multivariate (principal components and step-wise linear discriminant) analyses.

RESULTS

The monovariate analyses showed that radiotherapy significantly influenced the values of the parameters relating to nuclear size (nuclear area--NA), the frequency of small dense chromatin clumps (short run length emphasis--SRL) in the nuclei, and the overall chromatin condensation level (local mean--LM). The global effect corresponded to a decrease in the overall chromatin condensation level in the radioresistant cell-enriched MXT tumors. This decrease occurred concomitantly with an increase in the frequency of the small dense chromatin clumps in the nuclei and a decrease in the nuclear area. The multivariate analyses showed that it was possible to quantitate the proportion of "radiosensitive-like" and "radioresistant-like" cell nuclei in the various MXT tumor types under study.

CONCLUSIONS

The development of certain morphonuclear parameters, that is, the NA, the SRL, and the LM, could be proposed to predict the response of human tumors to radiotherapy as, indeed, could the quantitation of the proportion of radioresistant cells.

Morphonuclear characterization of drug resistance by means of digital cell-image analysis: an in vitro assessment

The prediction of tumor resistance to antineoplastic drugs remains an important challenge in cancer chemotherapy. Several methods have been proposed in this connection, but they present a number of problems such as clinical relevance and applicability. In the present work we put forward an original methodology to assess the drug sensitivity of cancer cells. For this purpose we submitted chemosensitive and chemoresistant cell lines to different anticancer drugs and monitored the cell growth and the drug-induced morphonuclear effects by means of digital cell-image analysis of Feulgen-stained nuclei. The results showed that drug-induced effects at the morphonuclear level correlated statistically with the effects produced at the cell proliferation level. For example, the mean nuclear size value increased as a function of the drugs' efficiency recorded at the cell proliferation level. In the same way, the frequency of large dense chromatin clumps also increased in accordance with the drugs' efficiency. The present work thus demonstrates that digital cell-image analysis can be applied to monitor the efficiency of chemotherapeutic treatment carried out on cell lines in vitro. The present methodology could possibly be used on solid tumors, from which biological material can be obtained serially by means of fine-needle aspiration. As evidence of this, the present methodology can also be applied to hematological cancers.

In vitro characterization of radiotherapy-induced morphonuclear modifications on chemosensitive as opposed to chemoresistant neoplastic cells

PURPOSE

We describe by means of digital cell image analysis the influence of X-ray radiation on three in vitro cultured cell lines for which we set up chemosensitive and chemoresistant variants.

METHODS AND MATERIALS

The three cell lines correspond to the MXT mouse mammary and the T24 and J82 neoplastic human bladder cells. The digital cell image analysis was carried out by computing morphometric (nuclear size), densitometric (proportion of cells in the G2 cell cycle phase), and textural features (chromatin pattern characteristics) on Feulgen-stained nuclei.

RESULTS

The results show that such digital cell image analyses make it possible to monitor radiotherapy-induced effects on these morphonuclear characteristics accurately. X-ray radiotherapy induces a dose-dependent increase in the proportion of cells in the G2 phase of the cell cycle along with a decrease in the overall chromatin condensation level. These two concomitant phenomena lead to a marked radiotherapy-induced increase in nuclear size. We also observed that radiotherapy-induced effects at the morphonuclear level are not only highly specific to the cell type analyzed, that is MXT mouse mammary or J82 or T24 human bladder carcinoma cells, but also to the fact that the cells are either chemosensitive or chemoresistant.

CONCLUSION

The digital cell image analyses of Feulgen-stained nuclei is helpful in monitoring the irradiation-induced morphonuclear modifications.

Monitoring of chemotherapy-induced morphonuclear modifications by means of digital cell-image analysis

We illustrate the potential application of digital cell-image analysis to characterize the morphonuclear modifications induced by various drugs including VP16, a podophyllotoxin derivative, PE1001, an investigational alkylating agent, and doxorubicin, an intercalating agent. Fifteen parameters representative of morphometric (nuclear area), densitometric (nuclear DNA content), and textural (chromatin organization, condensation, and distribution) features were computed on Feulgen-stained nuclei obtained from fine-needle aspirations serially performed during treatment on the MXT mouse mammary cancer model. We observed marked differences between the control and drug-treated MXT cell nuclei. However, mathematical data processing was necessary to improve the ratio of the chemotherapy-induced morphonuclear signal to the control biological morphonuclear signal. This data processing relies upon the use of principal-component analysis followed by the canonical transformation of data. The present method can be applied to all human cancers on which fine-needle aspiration can be performed.

Digital cell image analysis of verapamil-induced effects in chemosensitive and chemoresistant neoplastic cell lines

We used chemosensitive and chemoresistant variants of the neoplastic mouse MXT mammary and human J82 and T24 bladder cell lines to characterize verapamil-induced cell proliferation and morphonuclear modifications in drug-treated and untreated cells. Chemoresistance to vinorelbine (Navelbine, a Vinca alkaloid derivative), to DIAM3 (an investigational alkylating compound) and to Adriamycin (an intercalating agent) in the presence or absence of verapamil was monitored by means of the colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The results showed that verapamil restored a significant level of chemosensitivity in doses such as 1 microM or 10 microM in the three chemoresistant variants. The digital cell image analysis of Feulgen-stained T24-resistant cell nuclei revealed that verapamil restored the drug-treated cell kinetics and morphonuclear features observed in the sensitive counterpart especially with respect to the effects of Adriamycin. Interestingly, verapamil induced a highly significant chromatin decondensation in resistant but not in sensitive variants. Such verapamil-induced decondensation may favour the accessibility of drugs to their DNA targets. Therefore, in addition to the well-known action of the drug on the influx of a cytotoxic compound from the cellular to the intracellular compartment, verapamil might also favour the accessibility of the nucleus, to the drug.

An in vivo model for the experimental selection of drugs able to prevent immune complex glomerulonephritis

Polyclonal activation of lymphocytes and immune complex-mediated glomerular lesions were induced in C57Bl/6 mice by injecting bacterial lipopolysaccharide (LPS) twice a week for 2 weeks. The usefulness of such a model for in vivo evaluation of immunomodulatory and therapeutic effects of drugs, was investigated by treating mice with DIAM4, a cyclophosphazenic compound known to modulate polyclonal activation of lymphocytes and to prevent mouse lupus nephritis. Prevention of LPS-triggered lymphocyte polyclonal activation and glomerular lesions was observed in the DIAM4-treated mice. Such a model can be used conveniently to select compounds effective in the treatment of immune glomerulonephritis.

Digital morphonuclear analyses of sensitive versus resistant neoplastic cells to vinca-alkaloid, alkylating, and intercalating drugs

We tested 12 resistant cell lines in vitro in order to evaluate common morphonuclear characteristics induced by various cytotoxic drugs on cell lines of different origins. We used the MXT mouse mammary cancer and the neoplastic J82 and T24 human bladder cell lines, whose variants are either sensitive or resistant to a vinca alkaloid derivative (Navelbine, NVB), to an investigational alkylating agent (PE1001), and to Adriamycin (ADR). We tested cell population variants resistant to NVB + PE1001 + ADR. The level of chemoresistance was evaluated by a colorimetric assay assessing the 50% concentration-induced inhibition of cellular growth (IC50) brought about by each drug on the growth of each cell variant under study. We show that resistant neoplastic cell nuclei present common morphonuclear characteristics, independent of cell origin (neoplastic mouse mammary versus human bladder cells) and the drug used (vinca alkaloid, alkylating, and intercalating derivatives). Our results further indicate that the phenotype of resistant versus sensitive cells corresponds to cell nuclei populations with smaller nuclei and less nuclear DNA content and, as a consequence, a chromatin texture showing large pale areas with some hyperchromatic clumps.

Modulation of polyclonal activation of lymphocytes by cyclophosphazenic compounds bearing ethylene-imino groups and vectorized by polyamines

Cyclophosphazenic compounds bearing ethylene-imino groups are cytocydal chemicals which can modulate polyclonal activation of lymphocytes (PAL) and prevent the development of murine lupus. The effects on PAL of the different parts of these chemicals and of vectorization by polyamines have been investigated by treating lipopolysaccharide injected C57Bl/6 mice with various cyclophosphazenic compounds and thiotepa. The immune effects of the cyclophosphazenic substances have been found to be mediated by ethylene-imino groups and to be modulated by polyamine vectorization. These compounds might represent a new class of drugs for treatment of immune mediated diseases of the lupus type.