Leonardo Santi

Improved microfluorometric DNA determination in biological material using 33258 Hoechst

Abstract A simple and rapid microfluorometric method is described for the determination of DNA in submicrogram quantities using 33258 Hoechst fluorochrome. A high degree of reproducibility was obtained using calf thymus and phage DNA, mouse liver chromatin, and HeLa cells homogenate preparations. None or very little interference by the routinely used preparation reagents or by the cellular components was found. Compared to other commonly used procedures this innovative and versatile technique can be conveniently applied to DNA microdetermination for the high sensibility/reproducibility ratio and can also be used without the need of previous purification steps.

Treatment of Advanced Squamous-Cell Carcinoma of the Head and Neck with Alternating Chemotherapy and Radiotherapy

BACKGROUND For patients with advanced, unresectable squamous-cell carcinoma of the head and neck, radiotherapy is the standard treatment but has poor results. We therefore designed a randomized trial to determine whether alternating chemotherapy with radiotherapy would improve the survival of such patients. METHODS Patients in the trial had biopsy-confirmed unresectable, previously untreated Stage III or IV, squamous-cell carcinoma of the oral cavity, pharynx, or larynx. They were randomly assigned to chemotherapy consisting of four cycles of intravenous cisplatin (20 mg per square meter of body-surface area per day for five consecutive days) and fluorouracil (200 mg per square meter per day for five consecutive days) alternating with radiotherapy in three two-week courses (20 Gy per course; 2 Gy per day, five days per week), or to radiotherapy alone (up to 70 Gy; 2 Gy per day, five days per week). RESULTS The 80 patients given chemotherapy alternating with radiotherapy and the 77 given radiotherapy alone were comparable in terms of age, sex, performance status, disease stage, and site of the primary tumor. Complete responses were obtained in 42 percent of the patients in the combined-therapy group and 22 percent of those in the radiotherapy group (P = 0.037). The median survival was 16.5 months in the combined-therapy group and 11.7 months in the radiotherapy group (P less than 0.05); the 3-year survival was 41 percent and 23 percent, respectively. Severe mucositis occurred in 19 percent of the patients in the combined-therapy group and 18 percent of those in the radiotherapy group. CONCLUSIONS In patients with advanced unresectable squamous-cell carcinoma of the head and neck, chemotherapy alternating with radiotherapy increases the median survival and doubles the probability of survival for three years as compared with radiotherapy alone. However, since local disease cannot be controlled in over half the patients who receive the combined treatment and since almost two thirds die within three years, further improvements in management are necessary.

TIMP-2 over-expression reduces invasion and angiogenesis and protects B16F10 melanoma cells from apoptosis

The matrix metalloproteinase (MMP) inhibitor TIMP‐2 has a high specificity for gelatinase A/MMP‐2. An imbalance between gelatinase A and TIMP‐2 in favor of enzymatic activity is linked to the degradation of the extracellular matrix (ECM) associated with several physiologic and pathologic events, including angiogenesis, invasion and metastasis. Since TIMPs are secreted molecules, they have the potential to be used for gene therapy of certain tumors. We transfected B16F10 murine melanoma cells, a highly invasive and metastatic cell line, with an expression vector harboring a cDNA encoding for human TIMP‐2. The clones obtained were isolated and examined for TIMP‐2 over‐expression and changes in tumor cell phenotype. The amount of recombinant TIMP‐2 produced correlated with a reduction in invasion. In an in vivo angiogenesis assay, TIMP‐2‐transfected clones showed reduced levels of blood vessel formation, and in vitro conditioned media from TIMP‐2 transfectants showed diminished induction of endothelial cell migration and invasion. TIMP‐2 over‐expression limited tumor growth in vivo and neoangiogenesis when cells were injected subcutaneously in mice in the presence of Matrigel. However, TIMP‐2 over‐expressing clones were found to be more resistant to apoptosis than parental and control melanoma cells, while necrosis was increased. Our data confirm the role of TIMP‐2 in the down‐regulation of metastasis and angiogenesis but indicate a possible involvement in tumor cell survival. Int. J. Cancer 75:246–253, 1998.

Inhibition of angiogenesis and vascular tumor growth by interferon-producing cells: A gene therapy approach

We developed an in vivo gene therapy approach to characterize and optimize the anti-angiogenic activity of class I interferons (IFNs), using packaging cell lines producing an amphotropic LXSN-based retrovirus expressing either IFN-alpha1 (alpha1Am12), IFN-beta (betaAm12) murine cDNAs, or the vector alone (neoAm12). Pretreatment of endothelial-like Eahy926 cells in vitro with conditioned media (CM) from alpha1Am12 or betaAm12 cells for 48 hours significantly inhibited their migration and invasion as compared to neoAm12-CM-treated cells. betaAm12-CM also inhibited the formation of capillary-like structures on Matrigel by EAhy926 cells. In vivo, inclusion of the betaAm12 cells strongly inhibited, and alpha1Am12 partially inhibited, the angiogenic response in the Matrigel sponge model in both immune-competent and athymic nude mice. Electron microscopy showed a reduction of host cell infiltration in alpha1Am12- and betaAm12-containing sponges and reduction of invading tubular clefts of host cells as compared to controls. Finally, inoculation of either alpha1Am12 or betaAm12 cells (10%) along with a highly angiogenic Kaposis sarcoma cell line (90%) resulted in a powerful reduction of tumor growth in nude mice in vivo, as did infection with the interferon-alpha-producing retroviruses. These data suggest that a gene therapy approach using class I interferons can effectively inhibit tumor angiogenesis and growth of vascular tumors.

Combined chemotherapy and radiation therapy in advanced inoperable squamous cell carcinoma of the head and neck. The final report of a randomized trial

Between 1983 and 1986, the National Institute for Cancer Research in Genoa and affiliated institutions conducted a randomized study to compare two different ways of combining chemotherapy (CT) and radiation therapy (RT). One hundred sixteen patients were randomized to receive neoadjuvant CT followed by definitive RT (treatment arm A) or alternating CT and RT. In treatment arm A, RT consisted of 70 Gy to the involved areas and 50 Gy to the uninvolved neck at 2 Gy/fraction, five fractions per week. In treatment arm B, RT consisted of 60 Gy to involved areas and 50 Gy to the uninvolved neck in three courses of 20 Gy each, 2 Gy/fraction, ten fractions/2 weeks alternated with four courses of CT. CT consisted of vinblastine 6 mg/m2 intravenously followed 6 hours later by bleomycin 30 IU intramuscularly, day 1; methotrexate 200 mg intravenously, day 2; leucovorin rescue, day 3. CT was repeated every 2 weeks up to four courses. The same CT was used in both treatment arms of the study. Fifty‐five patients were entered in treatment arm A and 61 in treatment arm B. Complete responses were 7/48 and 19/57 in treatment arms A and B, respectively (P < 0.03). Four‐year progression‐free survival was 4% in treatment arm A and 12% in treatment arm B (P < 0.02), and four‐year survival was 10% in A and 22% in B (P < 0.02). Mucosal tolerance was significantly worse in treatment arm B (P < 0.00004). The subgroup analysis shows the major improvement of alternating CT and RT in patients with the worst prognostic characteristics.

MORTALITY AMONG SHIPYARD WORKERS IN GENOA, ITALY

The dockyards of Genoa are exposed to many known or suspect carcinogenic agents, namely, asbestos, silica, polycyclic aromatic hydrocarbons, and halogenated hydrocarbons; other possibly harmful substances are trace amounts of aromatic amines, welding smokes, paints, and lipid-removing solvents. A cohort study of causes of death of 2190 dockyard workers in Genoa was conducted between January 1, 1960 and December 31, 1975. Mortality rates were calculated for 20 different occupational categories, for which there exist different levels of exposure to noxious substances. Two control groups were selected: the general male population of Genoa and all male employees (462) of San Martino Hospital, Genoa for the same period of time. Causes of death that demonstrated significant excesses for both control groups were: cancer of the colon, excluding the rectum; cancer of the larynx; cancer of the lung, bronchus, and trachea; cancer of the kidney, urinary bladder, and other urinary organs; respiratory diseases; and cirrhosis of the liver. The data obtained from these 20 job categories revealed different types and levels of risk for various carcinogenic agents.

Quantitative correlations amongst alkaline DNA fragmentation, DNA covalent binding, mutagenicity in the Ames test and carcinogenicity, for 21 compounds ☆

21 compounds from different chemical classes were quantitatively compared for their carcinogenic potency according to 4 parameters: (1) potency in inducing covalent binding with DNA in vivo; (2) potency in inducing alkaline DNA fragmentation after treatment in vivo; (3) acute toxicity; (4) mutagenic potency in the Ames test. Establishing well-defined conditions for normalization of the different types of data and determination of the set that had to be submitted to statistical analysis appeared to be a difficult task, for which only compromise solutions were possible. A statistical analysis of the data suggested that all parameters considered were correlated with carcinogenic potency. However, we found that there are about 3 chances to 1 that carcinogenicity is better correlated with DNA covalent binding in vivo than it is to mutagenicity in the Ames test. With due precautions, even acute toxicity could be of predictive value. DNA adducts and DNA fragmentation, both in vivo, appeared to be 2 parameters strongly correlated between them. From a multivariate statistical analysis it appeared that: (1) a significant improvement of quantitative predictability is in principle obtainable with a battery of short-term test; and (2) the improvement is obtainable only if the short-term tests considered, while all correlated with carcinogenicity, are relatively independent amongst themselves.

Fibronectin: a chromatin-associated protein?

We have previously reported that chromatin preparations from human cultured fibroblasts contain a single homologous serum protein. In this paper we present evidence, based on immunological identity and physicochemical properties, that this serum protein is fibronectin. Furthermore, using a radioimmunoassay system, we have estimated that fibronectin represents about 0.7% of the total protein in both chromatin preparations and whole fibroblasts. Using a nitrocellulose filter assay system, we also show that fibronectin is a DNA-binding protein having an equilibrium constant of 4.6 x 10(-6) M. Equilibrium competition experiments have demonstrated that fibronectin has the ability to differentiate among nucleotides, indicating that fibronectin-DNA interaction is at least partially specific, and that a minimum polymer length of 12-18 nucleotides is required for effective binding to occur. Fibronectin has been isolated readily from plasma using DNA-affinity chromatography. We do not have direct evidence that fibronectin is an actual nonhistone chromosomal protein, but fibronectin is a DNA-binding protein (at least under in vitro assay conditions) and appears to be a normal constituent of chromatin as chromatin is currently isolated from cell nuclei.

A simplified procedure for the preparation of antibodies to serum fibronectin

In the present paper we describe in detail a simple procedure for the preparation of monospecific antisera to human and mouse serum fibronectin. A similar procedure could also be used to prepare antibodies to fibronectin from other species. The procedure, based on the recently reported affinity of fibronectin for gelatin, essentially consists of two steps (1) Immunization of rabbits with fibronectin purified from serum by affinity chromatography using gelatin coupled to CNBr-activated Sepharose 4B. (2) Absorption of the antiserum obtained by an immunoabsorbent prepared using fibronectin-free serum proteins that remained after absorbing serum with gelatin-Sepharose. The antisera obtained were monospecific, as determined by immunoelectrophoresis and did not show any difference with respect to antisera prepared by different procedures.

Hypercoagulable state induced by cytostatic drugs in stage ii breast cancer patients

An increased incidence of thromboembolic complications occurring in cancer patients during chemotherapy was recently reported. In view of this report, a study in 49 patients receiving adjuvant chemotherapy for Stage II breast cancer was begun in order to determine the effect of antineoplastic drugs on coagulation factors and platelet function. Among the coagulation factors, a significant decrease of thrombin time and partial prothrombin time was observed, whereas platelet function tests were unchanged. This finding suggests a trend towards hypercoagulability induced by chemotherapy. This effect should be considered when chemotherapy is employed in advanced cancer patients at high risk for thrombosis. Cancer 58:1032‐1036, 1986.