Alan C. Sartorelli

The Leukotriene C4 Transporter MRP1 Regulates CCL19 (MIP-3β, ELC)–Dependent Mobilization of Dendritic Cells to Lymph Nodes

Adaptive immune responses begin after antigen-bearing dendritic cells (DCs) traffic from peripheral tissues to lymph nodes. Here, we show that DC migration from skin to lymph nodes utilizes the leukotriene C(4) (LTC(4)) transporter multidrug resistance-associated protein 1 (MRP1). DC mobilization from the epidermis and trafficking into lymphatic vessels was greatly reduced in MRP1(-/-) mice, but migration was restored by exogenous cysteinyl leukotrienes LTC(4) or LTD(4). In vitro, these cysteinyl leukotrienes promoted optimal chemotaxis to the chemokine CCL19, but not to other related chemokines. Antagonism of CCL19 in vivo prevented DC migration out of the epidermis. Thus, MRP-1 regulates DC migration to lymph nodes, apparently by transporting LTC(4), which in turn promotes chemotaxis to CCL19 and mobilization of DCs from the epidermis.

Triapine (3-aminopyridine-2-carboxaldehyde- thiosemicarbazone): A potent inhibitor of ribonucleotide reductase activity with broad spectrum antitumor activity.

Previous studies from our laboratories have shown that (a) Triapine() is a potent inhibitor of ribonucleotide reductase activity and (b) hydroxyurea-resistant L1210 leukemia cells are fully sensitive to Triapine. In an analogous manner, Triapine was similarly active against the wild-type and a hydroxyurea-resistant subline of the human KB nasopharyngeal carcinoma. Triapine was active in vivo against the L1210 leukemia over a broad range of dosages and was curative for some mice. This agent also caused pronounced inhibition of the growth of the murine M109 lung carcinoma and human A2780 ovarian carcinoma xenografts in mice. Optimum anticancer activity required twice daily dosing due to the duration of inhibition of DNA synthesis which lasted about 10 hr in L1210 cells treated with Triapine in vivo. DNA synthesis in normal mouse tissues (i.e. duodenum and bone marrow) uniformly recovered faster than that in L1210 leukemia cells, demonstrating a pharmacological basis for the therapeutic index of this agent. Triapine was more potent than hydroxyurea in inhibiting DNA synthesis in L1210 cells in vivo, and the effects of Triapine were more pronounced. In addition, the duration of the inhibition of DNA synthesis in leukemia cells from mice treated with Triapine was considerably longer than in those from animals treated with hydroxyurea. Combination of Triapine with various classes of agents that damage DNA (e.g. etoposide, cisplatin, doxorubicin, and 1-acetyl-1,2-bis(methylsulfonyl)-2-(2-chloroethyl)hydrazine) resulted in synergistic inhibition of the L1210 leukemia, producing long-term survivors of tumor-bearing mice treated with several dosage levels of the combinations, whereas no enhancement of survival was found when Triapine was combined with gemcitabine or cytosine arabinoside. The findings demonstrate the superiority of Triapine over hydroxyurea as an anticancer agent and further suggest that prevention by Triapine of repair of DNA lesions created by agents that damage DNA may result in efficacious drug combinations for the treatment of cancer.

Randomized clinical trial of mitomycin c as an adjunct to radiotherapy in head and neck cancer

A randomized prospective clinical trial was carried out to assess the usefulness of the addition of mitomycin C to radiation therapy used alone or in combination with surgery for the treatment of squamous cell carcinoma of the head and neck region. One hundred and twenty patients with biopsy proven tumor of the oral cavity, oropharynx, larynx, hypopharynx, and nasopharynx were randomly assigned to receive or not receive mitomycin C; all other aspects were similar in the two treatment groups. One hundred and seventeen patients were evaluable with a median follow-up time of greater than 5 years. Acute and chronic normal tissue radiation reactions were equivalent in the two treatment groups. Hematologic and pulmonary toxicity were observed in the drug treated patients. Actuarial disease-free survival at 5 years was 49% in the radiation therapy group and 75% in the radiation therapy plus mitomycin C group, p less than 0.07. Local recurrence-free survival was 66% in the radiation therapy group and 87% in the radiation therapy plus mitomycin C group, p less than 0.02. The findings demonstrate that mitomycin C can be administered safely as an adjunct to radiation therapy in the treatment of head and neck cancer. The drug improves local tumor control without enhancing normal tissue radiation reactions.

Chemotherapy as an adjunct to radiation in the treatment of squamous cell carcinoma of the head and neck: results of the Yale Mitomycin Randomized Trials.

PURPOSE Two consecutive randomized trials were run at our institution using the bioreductive alkylating agent mitomycin as an adjunct to radiation therapy in an effort to improve outcome in patients with squamous cell carcinoma of the head and neck. METHODS Between 1980 and 1992, two consecutive randomized trials using mitomycin (trial 1) and mitomycin with dicumarol (trial 2) as an adjunct to radiation therapy in patients with squamous cell carcinoma of the head and neck were conducted at our institution. The patients were stratified by intent of therapy, extent of disease, and primary tumor site. Within each strata, patients were randomized to receive radiation therapy with or without mitomycin (trial 1) or mitomycin/dicumarol (trial 2). RESULTS A total of 203 patients were enrolled onto both trials, 195 of whom were eligible for analysis. Patients were equally balanced with respect to sex, age, extent of disease, primary site, radiation dose, and total duration of radiation treatment. Hematologic toxicities were more frequently noted in the drug-treated arms, but were acceptable with no drug-related treatment deaths. Nonhematologic toxicities were acceptable and not significantly different between the two arms. As of September 1995, with a median follow-up of 138 months, a statistically significant benefit occurred in the mitomycin arms with respect to cause-specific survival (0.74 +/- 0.05 v 0.51 +/- 0.05; P = .005), local recurrence-free survival (0.85 +/- 0.04 v 0.66 +/- 0.05; P = .002), and local regional recurrence-free survival (0.76 +/- 0.05 v 0.54 +/- 0.05; P = .003). No statistically significant difference in overall survival was obtained (0.48 +/- 0.05 mitomycin arms v 0.42 +/- 0.05 radiation alone). CONCLUSION The bioreductive alkylating agent mitomycin is a safe and effective adjunct to radiation therapy in the treatment of squamous cell carcinoma of the head and neck. The statistically and clinically significant improvement in local regional relapse and cause-specific survival obtained support the use of mitomycin as an adjunct to radiation therapy in the management of squamous cell carcinoma of the head and neck.

Mitomycin C as an adjunct to postoperative radiation therapy in squamous cell carcinoma of the head and neck: results from two randomized clinical trials.

PURPOSE This study was undertaken to assess the benefit of mitomycin C as an adjunct to postoperative radiation therapy in patients with operable squamous cell carcinoma of the head and neck. METHODS AND MATERIALS Between May 1980 and May 1991, 182 patients have been enrolled in two consecutive randomized clinical trials testing mitomycin C as an adjunct to radiation therapy in squamous cell carcinoma of the head and neck. In both trials, patients were stratified by stage, disease site and intent of therapy. This subset analysis includes 113 patients entered into these two randomized trials treated with surgery and postoperative radiation therapy. In the first trial, patients were randomized to receive standard postoperative radiation therapy alone compared with postoperative radiation therapy with concomitant mitomycin C. In the second trial, patients were randomized to postoperative radiation therapy or postoperative radiation therapy with concomitant mitomycin C plus dicoumarol. RESULTS As of November 1991, the 113 patients treated with surgery and postoperative radiation therapy in both trials had a median follow-up of 93 months. There have been a total of 12 local recurrences in the radiation therapy alone arm compared to 0 local recurrences in the radiation therapy/mitomycin C arm. There were eight regional recurrences in the radiation therapy alone arm compared with five regional recurrences in the mitomycin C arm. Patients in the mitomycin C arm experienced a superior 5-year actuarial local regional control rate (87% vs. 67%, p < .015) and a statistically significant disease-free survival benefit (67% vs. 44%, p < .03). Overall survival difference between the two arms (56% vs. 41%) has not reached statistical significance. CONCLUSIONS We conclude from these prospectively designed randomized clinical trials that in patients with operable head and neck cancer treated with surgery and postoperative radiation therapy, concomitant administration of mitomycin C with radiation therapy will result in a statistically significant disease-free survival and local regional control benefit. We are currently investigating the value of other bioreductive alkylating agents as adjuncts to radiation therapy in patients with squamous cell carcinoma of the head and neck.

Adriamycin: A proposal on the specificity of drug action

Abstract Adriamycin has been found to decrease the gel to liquid crystal transition temperature of liposomal membranes of varying compositions. However, when a low level of cardiolipin was inserted into a lecithin-containing membrane matrix, drug interaction caused the opposite effect on the thermal transition. It is suggested that this phenomenon may be indicative of specificity in the cytotoxic action of adriamycin on tumors, because evidence exists which indicates that certain neoplastic cells may contain cardiolipin in their plasma membrane and thus present a different surface to the drug than a non-malignant cell.

Ataxia-telangiectasia mutated kinase regulates ribonucleotide reductase and mitochondrial homeostasis

Ataxia-telangiectasia mutated (ATM) kinase orchestrates nuclear DNA damage responses but is proposed to be involved in other important and clinically relevant functions. Here, we provide evidence for what we believe are 2 novel and intertwined roles for ATM: the regulation of ribonucleotide reductase (RR), the rate-limiting enzyme in the de novo synthesis of deoxyribonucleoside triphosphates, and control of mitochondrial homeostasis. Ataxia-telangiectasia (A-T) patient fibroblasts, wild-type fibroblasts treated with the ATM inhibitor KU-55933, and cells in which RR is inhibited pharmacologically or by RNA interference (RNAi) each lead to mitochondrial DNA (mtDNA) depletion under normal growth conditions. Disruption of ATM signaling in primary A-T fibroblasts also leads to global dysregulation of the R1, R2, and p53R2 subunits of RR, abrogation of RR-dependent upregulation of mtDNA in response to ionizing radiation, high mitochondrial transcription factor A (mtTFA)/mtDNA ratios, and increased resistance to inhibitors of mitochondrial respiration and translation. Finally, there are reduced expression of the R1 subunit of RR and tissue-specific alterations of mtDNA copy number in ATM null mouse tissues, the latter being recapitulated in tissues from human A-T patients. Based on these results, we propose that disruption of RR and mitochondrial homeostasis contributes to the complex pathology of A-T and that RR genes are candidate disease loci in mtDNA-depletion syndromes.

Characterization of the biochemical mechanism of action of α-(N)-heterocyclic carboxaldehyde thiosemicarbazones

Abstract α-(N)-Heterocyclic carboxaldehyde thiosemicarbazones have been shown to be potent inhibitors of the biosynthesis of DNA in mammalian cells. Studies with transplanted murine neoplasms have demonstrated that the enzymatic site responsible for the blockade of DNA replication is at the level of ribonucleoside diphosphate reductase, an enzyme of critical importance for the generation of the deoxynucleoside triphosphate precursors of these macromolecules. Kinetic studies were carried out with a partially purified enzyme from a rat tumor in an effort to define the molecular mechanism by which agents of this class inhibit the activity of ribonucleoside diphosphate reductase. The concentration of the nucleoside diphosphate substrate, the allosteric activator ATP, or magnesium ion did not influence the inhibition by a representative derivative of this type of agent IQ-1. Dithiothreitol, a model dithiol used in place of the natural substrate thioredoxin, was partially competitive with the inhibitor. The results appear to be most compatible with a model in which the preformed metal chelate of IQ-1 interacts with the enzyme at or near the site occupied by the dithiol substrate. To ascertain some of the structural features required for inhibition of ribonucleoside diphosphate reductase activity, the inhibitory potency of a series of methyl and benzo derivatives of PT was measured. The results suggested that position 6 of PT and position 3 of IQ-1 are equivalent with respect to orientation of the inhibitor at the enzymatic binding site and that little or no tolerance exists for structural modification at this position. In a similar manner, substitution of the terminal amino group of the thiosemicarbazone side chain decreased enzyme inhibition, supporting the presence of a low bulk tolerance zone in this position. Further studies with these substituted derivatives were interpreted to be suggestive of the existence of a hydrophobic bonding zone adjacent to the inhibitor-binding site of the enzyme. These results were employed to design MAIQ-1, a derivative of this class with strong inhibitory potency for ribonucleoside diphosphate reductase, as well as the other necessary requisite properties for clinical trial as an antineoplastic agent.

Inhibitors of ribonucleotide reductase. Comparative effects of amino- and hydroxy-substituted pyridine-2-carboxaldehyde thiosemicarbazones.

A new series of alpha-(N)-heterocyclic carboxaldehyde thiosemicarbazones (HCTs) was studied for their effects on L1210 cell growth in culture, cell cycle transit, nucleic acid biosynthesis and ribonucleotide reductase activity. 3-Aminopyridine-2-carboxaldehyde thiosemicarbazone (3-AP) and 3-amino-4-methylpyridine-2-carboxaldehyde thiosemicarbazone (3-AMP) were the most active compounds tested with respect to inhibition of cell growth and ribonucleotide reductase activity. 5-Aminopyridine-2-carboxaldehyde thiosemicarbazone (5-AP) and 4-methyl-5-aminopyridine-2-carboxaldehyde thiosemicarbazone (5-AMP) were slightly less active. 3-AP, 3-AMP, 5-AP and 5-AMP inhibited the incorporation of [3H]thymidine into DNA without affecting the rate of incorporation of [3H]uridine into RNA. The uptake and incorporation of [14C]cytidine into cellular ribonucleotides and RNA, respectively, were not decreased by 3-AP or 3-AMP; however, the incorporation of cytidine into DNA via ribonucleotide reductase was inhibited markedly. Thus, a pronounced decrease in the formation of [14C]deoxyribonucleotides from radioactive cytidine occurred in the acid-soluble fraction of 3-AP- and 3-AMP-treated L1210 cells. Consistent with an inhibition of DNA replication that occurred at relatively low concentrations of 3-AP and 3-AMP, cells gradually accumulated in the S-phase of the cell cycle; at higher concentrations of 3-AP and 3-AMP, a more rapid accumulation of cells in the G0/G1 phase of the cell cycle occurred, with the loss of the S-phase population, implying that a second less sensitive metabolic lesion was created by the HCTs. N-Acetylation of 3-AMP resulted in a compound that was 10-fold less active as an inhibitor of ribonucleotide reductase activity and 8-fold less active as an inhibitor of L1210 cell growth. N-Acetylation of either 5-AP or 5-AMP did not alter the inhibitory properties of these compounds. The results obtained provide an experimental rationale for the further development of the HCTs, particularly 3-AP and 3-AMP, as potential drugs for clinical use in the treatment of cancer.

Adriamycin-induced changes in the surface membrane of sarcoma 180 ascites cells

Adriamycin increases (a) the rate of agglutination of Sarcoma 180 cells by concanavalin A after brief exposure of 2-3 h and (b) membrane fluidity as measured by ESR within 30 min of exposure at concentrations of the anthracycline of 10(-7)-10(-5) M. The effect of adriamycin on agglutination is not due to an increase in the number of surface receptors for concanavalin A, since the extent of binding of the lectin is not altered by adriamycin and no change occurs in the rate of occupancy of the concanavalin A binding sites by the lectin in cells treated with the antibiotic. The order parameter, a measurement of membrane fluidity, decreases in cells exposed to adriamycin and is dose-related. The results indicate that adriamycin can induce changes in the surface membrane of Sarcoma 180 cells within a brief period of exposure to a low but cytotoxic level of this agent.