Skin benefits of postbiotics derived from Micrococcus luteus derived from human skin: an untapped potential for dermatological health

BACKGROUND

The skin microbiome, a diverse community of microorganisms, plays a crucial role in maintaining skin health. Among these microorganisms, the gram-positive bacterium Micrococcus luteus exhibits potential for promoting skin health. This study focuses on postbiotics derived from M. luteus YM-4, a strain isolated from human skin.

OBJECTIVE

Our objective is to explore the beneficial effects of YM-4 culture filtrate on dermatological health, including enhancing barrier function, modulating immune response, and aiding recovery from environmental damage.

METHODS

The effects of the YM-4 culture filtrate were tested on human keratinocytes and fibroblasts under various conditions using real-time PCR for gene expression analysis and fibroblast migration assays. A dehydration-simulated model was employed to prepare RNA-Seq samples from HaCaT cells treated with the YM-4 culture filtrate. Differentially expressed genes were identified and functionally classified through k-means clustering, gene ontology terms enrichment analyses, and protein-protein interactions mapping.

RESULTS

The YM-4 culture filtrate enhanced the expression of genes involved in skin hydration, hyaluronic acid synthesis, barrier function, and cell proliferation. It also reduced inflammation markers in keratinocytes and fibroblasts under stress conditions. It mitigated UVB-induced collagen degradation while promoted collagen synthesis, suggesting anti-aging properties, and accelerated wound healing processes by promoting cell proliferation and migration. RNA sequencing analysis revealed that the YM-4 culture filtrate could reverse dehydration-induced transcriptional changes towards a state similar to untreated cells.

CONCLUSION

M. luteus YM-4 culture filtrate exhibits significant therapeutic potential for dermatological applications.

Synthesis of a covalent epirubicin-(C(3)-amide)-anti-HER2/neu immunochemotherapeutic utilizing a UV-photoactivated anthracycline intermediate

The C(3)-monoamine on the carbohydrate moiety (daunosamine -NH(2)-3') of epirubicin was reacted under anhydrous conditions with succinimidyl 4,4-azipentanoate to create a covalent UV-photoactivated epirubicin-(C(3)-amide) intermediate with primary amine-reactive properties. A synthetic covalent bond between the UV-photoactivated epirubicin-(C(3)-amide) intermediate and the ɛ-amine of lysine residues within the amino acid sequence of anti-HER2/neu monoclonal immunoglobulin was subsequently created by exposure to UV light (354 nm) for 15 minutes. Size-separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis combined with immunodetection analysis and chemiluminescent autoradiographic imaging revealed a lack of IgG-IgG polymerization or degradative protein fragmentation of the covalent epirubicin-(C(3)-amide)-[anti-HER2/neu] immunochemotherapeutic. Retained binding-avidity of epirubicin-(C(3)-amide)-[anti-HER2/neu] was validated by cell-ELISA utilizing monolayer populations of chemotherapeutic-resistant mammary adenocarcinoma SKBr-3 which highly overexpress membrane-associated HER2/neu complexes. Between epirubicin-equivalent concentrations of 10(-10) to 10(-6) M the covalent epirubicin-(C(3)-amide)-[anti-HER2/neu] immunochemotherapeutic consistently evoked levels of cytotoxic anti-neoplastic potency that were highly analogous to chemotherapeutic-equivalent concentrations of epirubicin. Cytotoxic anti-neoplastic potency of epirubicin-(C(3)-amide)-[anti-HER2/neu] against chemotherapeutic-resistant mammary adenocarcinoma SKBr-3 challenged with epirubicin-(C(3)-amide)-[anti-HER2/neu] at an epirubicin-equivalent concentration of 10(-6) M was 88.5% (e.g., 11.5% residual survival). Between final epirubicin-equivalent concentrations of 10(-8) and 10(-7) M there was a marked threshold increase in the mean cytotoxic anti-neoplastic activity for epirubicin-(C(3)-amide)-[anti-HER2/neu] from 9.9% to 66.9% (90.2% to 33.1% residual survival).

Maintenance chemotherapy for ovarian cancer

BACKGROUND

Epithelial ovarian cancer accounts for about 90% of all cases of ovarian cancer. Debulking surgery and six courses of platinum-based chemotherapy results in complete clinical remission (CCR) in up to 75% of cases. However, 75% of the responders will relapse within a median time of 18 to 28 months and only 20% to 40% of women will survive beyond five years. It has been suggested that maintenance chemotherapy could assist in prolonging remission. To date, there has not been a systematic review on the impact of maintenance chemotherapy for epithelial ovarian cancer.

OBJECTIVES

To assess the effectiveness and toxicity of maintenance chemotherapy for epithelial ovarian cancer and to evaluate the impact on quality of life (QoL).

SEARCH STRATEGY

We searched the Cochrane Gynaecological Cancer Review Group Specialized Register, The Cochrane Central Register of Controlled Trails (CENTRAL, The Cochrane Library Issue1, 2009), MEDLINE, EMBASE, PubMed, CBMdisc, CNKI and VIP (to May 2009). We collected information from ongoing trials, checked reference lists of published articles and consulted experts in the field.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing maintenance chemotherapy with no further intervention, maintenance radiotherapy or other maintenance therapy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for eligibility and quality and extracted data. We analysed overall survival (OS) and progression free survival (PFS) rates as dichotomous variables. Toxicity and QoL data were extracted where present. All analyses were based on intention to treat (ITT) on the endpoint of survival. We also analysed data by subgroups of drugs.

MAIN RESULTS

We included six trials(902 women). When all chemotherapy regimens were combined, meta-analysis indicated no significant difference in 3, 5 and 10-year OS or PFS. For 5-year OS, the combined relative risk (RR) was 1.07 (95% confidence interval (CI) 0.91 to 1.27) and for the 5-year PFS the combined RR was 1.18 (95% CI 0.88 to 1.58). Results were very similar when trials of different regimens were analysed. Comparing chemotherapy with radiotherapy, only the RR for 10-year PFS in pathological complete remission was in favour of whole abdominal radiotherapy 0.51 (95% CI 0.27 to 1.00), while 3 and 5-year OS rates have no significant difference between the two groups.

AUTHORS' CONCLUSIONS

There is no evidence to suggest that the use of platinum agents or doxorubicin used as maintenance chemotherapy is more effective than observation alone. Further investigations regarding the effect of paclitaxel used as maintenance chemotherapy are required.

Cardiac safety and antitumoral activity of a new nitric oxide derivative of pegylated epirubicin in mice

The use of epirubicin is limited by the risk of a dilatory congestive heart failure that develops as a consequence of induction of a mitochondrial-dependent cardiomyocyte apoptosis. In a previous in-vitro study, we have provided evidence that a new formulation of pegylated epirubicin- bearing moieties that release nitric oxide, named BP-747, exerted a potent antitumoral activity against a colon cancer cell line, which was completely devoid of cytotoxic activity against cardiomyocytes. The aim of this study was to investigate the antitumoral and cardiotoxic profile of BP-747 in Caco-2 and SKOV-2 tumor-bearing mice. Epirubicin-induced cardiomyopathy was detected by clinical (survival, weight loss), anatomical (heart weight loss) and biochemical evaluations (measurement of serum troponin and creatine phosphokinase levels). The antitumoral activity was investigated by the measurement of tumor diameters and weight. In comparison with free epirubicin and pegylated epirubicin, BP-747 showed more potent antineoplastic effects, as demonstrated by the 95% reduction of tumor volume. Moreover, while administration of epirubicin and pegylated epirubicin resulted in the development of a severe anthracycline cardiomyopathy, BP-747-treated mice were virtually devoid of clinical and biochemical signs of cardiotoxicity. The present data provide evidence that addition of a nitric oxide-releasing moiety to pegylated epirubicin confers a new and unique cytotoxic profile to the drug.

Four-Modality Therapy in Malignant Pleural Mesothelioma: A Phase II Study

BACKGROUND

Treatment approaches in malignant pleural mesothelioma (MPM) patients range from mere palliation to aggressive anticancer therapy, and there is currently no consensus on the optimal therapeutic strategy. In 1999, we began a phase II study to investigate four-modality treatment of advanced stage MPM.

METHODS

From 1999 to 2004, 49 patients with International Mesothelioma Interest Group stage II-III MPM underwent four-modality treatment with intrapleural preoperative interleukin-2 (18 x 10(6) UI/day for 3 days), pleurectomy/decortication, intrapleural postoperative epidoxorubicin (25 mg/m2 for 3 days), interleukin-2 (18 x 10(6) UI/day for 3 days), adjuvant radiotherapy (30 Gy), systemic chemotherapy (cisplatin 80 mg/m2 day 1, gemcitabine 1250 mg/m2 days 1 and 8 for up to six courses) and long-term subcutaneous interleukin-2 (3 x 10(6) UI/day on 3 days per week).

RESULTS

Patients included 41 men and eight women with a median age of 61 years (range, 41-77). All patients were diagnosed with MPM by thoracoscopy before inclusion. There was no postoperative mortality. Postoperative morbidity included bleeding (n = 1) and arrhythmias (n = 3). After a median follow-up of 59 months (range, 14-81), 13 patients are still alive and the median actuarial survival is 26 months (31 and 21 months for stages II and III, respectively). The 2- and 5-year actuarial survival rates were 60.2% and 23.3%, respectively. Baseline Eastern Cooperative Oncology Group performance status significantly influenced survival time (p = 0.02).

CONCLUSION

The four-modality treatment that we adopted for advanced-stage MPM was feasible, well tolerated by most of the patients, and produced a favorable median survival. This treatment approach warrants further investigation.

Epirubicin Glucuronidation and UGT2B7 Developmental Expression

The usefulness of epirubicin in the treatment of adult and childhood malignant diseases is related in part to the potential reduction in cardiac toxicity compared with that of other anthracyclines given at equivalent doses. An important pathway for epirubicin detoxification is UGT2B7-dependent glucuronidation. This study was implemented to provide a preclinical evaluation of the metabolism of epirubicin with respect to age-related changes in epirubicin glucuronidation in pediatric liver microsomes. Rates of epirubicin glucuronidation and levels of UGT2B7 were determined for liver microsomes from four pediatric age categories (n = 32) and one adult age category (n = 8). Both sets of data showed an increase in UGT2B7 activity and content with increasing age. Epirubicin glucuronidation activity in the adult group was statistically higher compared with all pediatric age groups (p < or = 0.01). UGT2B7 expression also was statistically higher in adults compared with children below 11 years of age, with evidence of significant differences in protein levels among the pediatric age categories. A positive correlation (r = 0.68) between UGT2B7 levels and postnatal age was observed, suggesting a progressive increase in UGT2B7 protein expression with increasing age. However, allometric scaling using the (3/4) power rule suggested no difference in activity between any of the pediatric age categories and the adult, although only a single neonatal sample was included in the analysis. In summary, these in vitro data show differences in epirubicin glucuronidation and UGT2B7 content within pediatric age groups and support the use of epirubicin in pediatric patients at least 6 months of age.

The length of treatment of aggressive non-Hodgkin's lymphomas established according to the international prognostic index score: long-term results of the GISL LA03 study

OBJECTIVES

To compare two different schedules of two different anthracycline-containing regimens, where length of treatment is modulated according to the international prognostic index (IPI) in patients with aggressive non-Hodgkin's Lymphoma (NHL).

METHODS

In 1993 the Gruppo Italiano per lo Studio dei Linfomi (GISL) started a randomized 2 x 2 factorial phase III clinical trial for patients with newly diagnosed aggressive NHL comparing ProME(Epidoxorubicin)CE-CytaBOM (PE-C) to ProMI(Idarubicin)CE-CytaBOM (PI-C) and a fixed to a flexible treatment schedule where anthracycline dose was to be modulated according to observed hematological toxicity. Patients with low or low-intermediate IPI (IPI 0-2) and those with intermediate-high or high IPI (IPI 3-5) should receive six or eight courses, respectively. Involved-field radiotherapy was allowed for patients with initial bulky disease or with residual masses.

RESULTS

Three hundred and fifty-six patients were registered into the study and randomized. Patients were well balanced among the four study arms in terms of clinical characteristics and prognostic factors. Three hundred and forty-five patients were available for evaluation of study endpoints. At the end of induction therapy complete remission rate was 61%, 5-year failure-free survival (FFS) rate was 40% and 5-year overall survival (OS) rate was 59%; no differences were observed according to treatment arms. Patients in the flexible arm received higher dose intensity of anthracycline (P < 0.001) with no apparent increase in toxicity. However, the flexible schedule was not superior to the fixed one. Patients with IPI 3-5 showed lower response rates (45% vs. 67%: P < 0.0001) and lower 5-year FFS (29% vs. 45%: P < 0.0001) compared to those with IPI 0-2.

CONCLUSIONS

six courses of fixed or flexible PE-C or PI-C can determine a promising success rate in patients with advanced aggressive NHL with IPI 0-2, whereas the same regimens are less effective in patients with IPI 3-5, even if two additional courses are delivered. For the latter group of patients innovative approaches are warranted.

Nitric oxide modulates proapoptotic and antiapoptotic properties of chemotherapy agents: the case of NO-pegylated epirubicin

The use of the anthracycline epirubicin (EPI) is limited by the risk of a dilatory congestive heart failure that develops as a consequence of induction of a mitochondrial-dependent cardiomyocyte and endothelial cell apoptosis. Nitric oxide (NO) increases the antitumoral activity of several chemotherapics, while it provides protection against apoptosis induced by oxidative stress both in endothelial cells and cardiomyocytes. The aim of the present study was to investigate whether the addition of an NO-releasing moiety to a pegylated derivative of EPI (p-EPI-NO) confers to the drug a different cytotoxic profile against tumoral and normal cells. The cytotoxic profile of the drugs was investigated in Caco-2 cell line, in embryonic rat heart-derived myoblasts (H9c2), in adult cardiomyocytes, and in endothelial cells (HUVEC). p-EPI-NO was more efficient than EPI in inducing Caco-2 cell apoptosis, while it spared HUVEC, H9c2 cells and adult cardiomyocytes from EPI-induced toxicity. Exposure of cells to p-EPI-NO resulted in a NO-mediated inhibition of cellular respiration followed by mitochondrial membrane depolarization and cell death in Caco-2 cells but not in HUVEC and H9c2 cells in which mitochondrial membrane polarization was maintained at the expense of glycolytically generated ATP. These findings indicate that addition of an NO-releasing moiety to p-EPI increases the anti-neoplastic activity of the drug, while it reduces its cytotoxicity against nonneoplastic cells.

Pathological complete response rates comparing 3 versus 6 cycles of epidoxorubicin and docetaxel in the neoadjuvant setting of patients with stage II and III breast cancer

We conducted a prospective randomized study to compare the results of 3 cycles of epidoxorubicin/docetaxel to 6 cycles of epidoxorubicin/docetaxel prior to surgery in breast cancer patients with clinical stages II and III. Forty-five patients eligible for neoadjuvant chemotherapy were randomly assigned to receive either 3 (group 1) or 6 (group 2) cycles of epidoxorubicin/docetaxel prior to surgery. Chemotherapy consisted of epidoxorubicin 75 mg/m and docetaxel 75 mg/m on day 1 in 3-week cycles. The primary endpoint was the pathological complete response (pCR) rate; secondary endpoints were the rates of breast-conserving surgery and the axillary lymph node status in both groups. A pCR occurred in 10% (two of 20) in Group 1 and in 36% (nine of 25) in Group 2, which was statistically significant (p=0.045). Breast-conserving surgery could be performed in 70% (14 of 20) in Group 1 and in 76% (19 of 25) in Group 2 (p=0.065). Axillary lymph node status was negative in 45% (nine of 20) in Group 1 and 52% (13 of 25) in Group 2 (p=0.86). We conclude that 6 cycles of pre-operative epidoxorubicin/docetaxel versus 3 cycles of pre-operative epidoxorubicin/docetaxel significantly increases the pCR rates for breast cancer patients.

Preoperative chemotherapy with epidoxorubicin, docetaxel and capecitabine plus pegfilgrastim in patients with primary breast cancer

The objective of this pilot trial was to evaluate the safety and activity profile of epidoxorubicin, docetaxel and oral capecitabine plus pegfilgrastim (TEX+P) as preoperative first-line treatment for patients with breast cancer. Eleven consecutive patients were enrolled in this prospective clinical pilot trial. Preoperative treatment consisted of epidoxorubicin [75 mg/m2 body surface area (BSA)] and docetaxel (75 mg/m2 BSA) administered sequentially on day 1 in combination with oral capecitabine 2000 mg/m2 daily divided into two doses on days 1-14 of each 3-week treatment cycle. Pegfilgrastim 6 mg fixed dose was administered s.c. on day 2 of every treatment cycle. Patients received a total of 58 cycles (median 6 cycles, range 1-6) of this therapeutic regimen. Outpatient TEX+P was well tolerated. No WHO grade IV toxicity was observed. A pathological major response to this preoperative therapy regimen could be demonstrated in eight of nine evaluable patients leading to breast-conserving surgery in seven of nine evaluable patients. We conclude that outpatient TEX+P is safe in the neoadjuvant treatment of patients with primary breast cancer. Thus, this regimen can be considered for further clinical trials.

Influence of the structure of new anthracycline antibiotics on their biological properties

In the search for new derivatives of anthracycline antibiotics with advantageous biological properties, particularly with lower toxicity and/or higher activity, a series of new analogs of antibiotics applied in therapy such as daunorubicin, doxorubicin, as well as epidoxorubicin and, for comparison, analogs of epidaunorubicin, have been synthesized. Our results show that the new derivatives have antiproliferative activities similar to or higher than the parent antibiotics. The toxicities of these analogs were significantly lower, with LD50 values from 1.8- to 18.4-fold higher than the referential drugs. Cardiotoxicity determinations, using male mice treated with a single dose of 75% of the LD50 values of all tested compounds, indicated that the cardiotoxicity of the new analogs is significantly lower than that of the parent drugs.

Long-Term Follow-Up of a Pilot Phase II Study with Neoadjuvant Epidoxorubicin, Etoposide and Cisplatin in Gastric Cancer

OBJECTIVE

The prognosis in T3-T4 or N+ gastric cancer is dismal, and the role of adjuvant therapy remains uncertain. Neoadjuvant chemotherapy could improve both resectability and survival. Here, we report the results of the long-term follow-up of a pilot study aimed at evaluating a neoadjuvant treatment in a group of patients carefully staged by computed tomography (CT), endoscopic ultrasound and laparoscopy.

METHODS

Twenty-five stage II-III patients with histologically proven gastric adenocarcinoma were enrolled in the study. All patients gave informed consent and were thoroughly staged. Patients were treated with epidoxorubicin (40 mg/m2 i.v.) on days 1 and 4, etoposide (VP-16; 100 mg/m2) on days 1, 3 and 4 and cisplatinum (80 mg/m2) on day 2, every 21-28 days for 3 pre-operative cycles before CT clinical restaging followed by laparotomy and D2 gastrectomy. Three further cycles of chemotherapy were planned after radical surgery.

RESULTS

Twenty-four patients received the planned pre-operative chemotherapy and underwent surgical resection; total (13 patients) or subtotal (7 patients) R0 D2 gastrectomy was possible in 20 patients. One patient died as a result of gastric bleeding. Perioperative complications occurred in 5 patients (failure of anastomosis in 1 patient and wound infection in the other 4). The pathologic response rate included 7 partial responses (29.1%) and 10 patients with stable disease (41.7%). The main toxicity was grade 3/4 neutropenia (68%), which occurred more frequently during the postoperative chemotherapy, and fatigue (68%). Fever or infection, however, were never observed. The median disease-free survival was 37 months, and median survival has not been reached after 40 months of median follow-up. One-, 2- and 3-year survival rates were 80, 64 and 60%, respectively.

CONCLUSION

The notable long-term survival in the present study suggests a comparison between the neoadjuvant approach, including new drug combinations, and adjuvant chemo- or chemoradio-therapy in locally advanced gastric cancer.

Evaluation of the epidoxorubicin--formaldehyde conjugate, epidoxoform, in a mouse mammary carcinoma model

This study was conducted to evaluate the toxicity and efficacy of Epidoxoform, a prodrug of the active metabolite of epidoxorubicin, in a mouse model of mammary carcinoma. A dose escalation trial established a maximal tolerated dose of 20 mg/kg given intraperitoneally (i.p.) to 6-8 week old female C3 HeJ mice. Two days following injection of 10(6) Gollin-B mouse mammary tumor cells into the mammary fat pad, Epidoxoform was given and tumor growth compared to mice treated similarly with the maximum tolerated dose of epidoxorubicin and untreated controls. In all efficacy trials, a significant difference was found for tumor volume between Epidoxoform and epidoxorubicin treated mice and controls. In mice treated with a two-dose regimen, significantly increased efficacy was also found between Epidoxoform compared to epidoxorubicin. Epidoxoform appears to be efficacious in this model of mammary carcinoma, with improved efficacy over the parent compound epidoxorubicin. Further evaluation of this analogue appears warranted.

Development of dextran derivatives with cytotoxic effects in human urinary bladder cancer cell lines

BACKGROUND

In a previous study we reported on a new approach describing intravesical instillation of charged dextran in patients with superficial bladder carcinoma. The cationic derivative showed a strong tumor-selective accumulation. To develop this approach, the present study investigates the cytotoxic effect of cationic dextran derivatives on two urinary bladder cancer cell lines (J82 and 5637).

METHODS

The dextran conjugates were prepared by periodate activation and subsequent coupling by reductive amination. A fluorimetric cytotoxicity assay (FMCA) was used for the cytotoxicity assay. The tumor cells were seeded into 96-well microtiter plates and different cationic dextran derivatives were added and incubated for 72 hours.

RESULTS

The results showed that cationic epirubicin-dextran had a clear inhibitory effect on the growth in both cell lines (40-95% growth inhibition). The corresponding values for epirubicin (the reference) was 90-100% inhibition. Interestingly, cationic dextran had, by itself, a growth inhibitory effect. This cytotoxic effect could be strongly enhanced to be almost equal to the reference by changing the cationic sidegroup to aminohexane. Dextran alone showed no effect.

CONCLUSION

The finding that cationic dextran by itself can be made cytotoxic, together with its capacity to accumulate in superficial bladder cancer, suggests possibilities for new therapeutic constructs. Cationic dextran with different cationic side-groups and in combination with cytotoxic drugs will be studied further. The cytotoxic mechanism needs to be elucidated.

[The effect of small cell lung cancer extension on secretion of interleukin-2 (IL-2) and interferon gamma (IFM gamma) in whole blood culture stimulated with mitogens]

The aim of this study was to assess the role of SCLC extension on II-2 and IFN gamma secretion in whole blood cell cultures stimulated with mitogens. Material consisted of 42 SCLC patients, 19 with extensive and 23 with limited disease. In 22 patients partial or complete regression of tumour occurred after treatment. There was a tendency to lower II-2 and IFN gamma secretion before treatment in patients with extensive disease in comparison to those with limited lesions but this was not statistically significant. The ability to secrete cytokines in 22 patients after partial or complete regression of tumour decreased or increased but median values after treatment were not statistically different from those before treatment.

Multidrug resistance protein functionality: no effect of intracellular or extracellular pH changes

A major problem in the treatment of cancer is cellular resistance to cytotoxic drugs. In tumor cells in vitro, the development of multidrug resistance is usually accompanied by increased expression of drug transporters, either P-glycoprotein (P-gp) or multidrug resistance-associated protein (MRP(1)). Both proteins belong to the superfamily of ATP-binding cassette (ABC) transporter proteins and mediate the transport of a broad range of drugs. Altenberg et al. (Proc Natl Acad Sci USA90: 9735-9738, 1993) have shown that changes in intra- or extracellular pH do not mediate P-gp-dependent multidrug resistance. Therefore, we similarly studied whether changes in intra- or extracellular pH could mediate MRP(1)-dependent multidrug resistance. In particular, we measured the MRP(1)-mediated efflux of hydroxyrubicin from GLC4/ADR cells. Since hydroxyrubicin is a fully neutral anthracycline derivative that has no deprotonable function at pH lower than 10 and so cannot accumulate in non-nuclear compartments under the influence of pH or transmembrane gradients, we hypothesized that any modifications of its kinetics of efflux as a function of pH can be assigned to a modification of the transporter efficiency. However, as our data show, modifications of extra- and/or intracellular pH yielded no modification of the MRP(1)-mediated efflux of hydroxyrubicin.

Inhibition of the P-glycoprotein- and multidrug resistance protein-mediated efflux of anthracyclines and calceinacetoxymethyl ester by PAK-104P

Multidrug resistance phenotype in mammalian cells is often correlated with overexpression of P-glycoprotein or Multidrug Resistance-Associated protein (MRP(1)). Both proteins are energy-dependent drug efflux pumps that efficiently reduce the intracellular accumulation and hence the cytotoxicity of many natural cytotoxins. Overexpression of these transporters by tumor cells is thought to be a significant factor in both intrinsic and acquired resistance to anticancer drugs. Consequently a great deal of interest is focused on identifying chemical agents that can either antagonise drug transport by these proteins or that can inhibit the proliferation of tumors cells despite the expression of these transporters. P-glycoprotein-mediated multidrug resistance is reversed by a variety of compounds, but surprisingly, few agents reverse the MRP(1)-mediated multidrug resistance. However, it has recently been shown that 2-[4-(diphenylmethyl)-1-piperazinyl]ethyl-5-(trans-4,6-dimethyl-1, 3, 2-dioxaphosphorinan-2-yl)-2, 6-dimethyl-4-(3-nitrophenyl)-3-pyridinecarboxylate P oxide (PAK-104P) was able to inhibit the P-glycoprotein and MRP(1)-mediated efflux of several compounds. Understanding of the interactions between transporters and multidrug resistance reversing agents is important in the design of more effective multidrug resistance modulators. We now examined the effect of PAK-104P on Pgp-and MRP1-mediated efflux of three anthracyclines, daunorubicin, pirarubicin, hydroxydoxorubicin and of calcein acetoxymethyl ester and calcein. Our data show that PAK-104P non-competitively inhibits the P-glycoprotein-mediated efflux of anthracycline derivatives and calcein acetoxymethyl ester with an inhibitory constant K(I)=0. 25+/-0.05 microM. PAK-104P also non-competitively inhibits the MRP(1)-mediated efflux of daunorubicin, pirarubicin, hydroxyrubicin, calcein acetoxymethyl ester and calcein. However, surprisingly, in this case the K(I) values obtained were very different ranging from 0.06 for hydroxyrubicin to 10 microM for calcein. These data strongly suggested the existence of two different mechanisms for the inhibition by PAK-104P of the MRP(1)-mediated efflux of molecules: a first mechanism, involving a low-affinity site for PAK-104P, and which would concern molecules such as calcein, cysteinyl leukotriene LCT(4) etc. whose efflux do not depend on glutathione. A second mechanism involving a high-affinity site for PAK-104P and which would concern molecules such as anthracyclines, calcein acetoxymethyl ester whose efflux depends on the presence of glutathione.

Crystal structure of epidoxorubicin-formaldehyde virtual crosslink of DNA and evidence for its formation in human breast-cancer cells

Epidoxorubicin and daunorubicin are proposed to be cytotoxic to tumor cells by catalyzing production of formaldehyde through redox cycling and using the formaldehyde for covalent attachment to DNA at G bases. The crystal structure of epidoxorubicin covalently bound to a d(CGCGCG) oligomer was determined to 1.6 A resolution. The structure reveals slightly distorted B-form DNA bearing two molecules of epidoxorubicin symmetrically intercalated at the termini, with each covalently attached from its N3' to N2 of a G base via a CH2 group from the formaldehyde. The structure is analogous to daunorubicin covalently bound to d(CGCGCG) determined previously, except for additional hydrogen bonding from the epimeric O4' to O2 of a C base. The role of drug-DNA covalent bonding in cells was investigated with synthetic epidoxorubicin-formaldehyde conjugate (Epidoxoform) and synthetic daunorubicin-formaldehyde conjugate (Daunoform). Uptake and location of drug fluorophore in doxorubicin-resistant human breast-cancer cells (MCF-7/ADR cells) was observed by fluorescence microscopy and flow cytometry. The fluorophore of Daunoform appeared more rapidly in cells and was released more rapidly from cells than the fluorophore of Epidoxoform over a 3 h exposure period. The fluorophore appeared predominantly in the nucleus of cells treated with both conjugates. The difference in uptake is explained in terms of the slower rate of hydrolysis of Epidoxoform to the species reactive with DNA and a proposed slower release from DNA based upon the crystal structures.

Nuclear targeting and nuclear retention of anthracycline-formaldehyde conjugates implicates DNA covalent bonding in the cytotoxic mechanism of anthracyclines

The anthracycline, antitumor drugs doxorubicin (DOX), daunorubicin (DAU), and epidoxorubicin (EPI) catalyze production of formaldehyde through induction of oxidative stress. The formaldehyde then mediates covalent bonding of the drugs to DNA. Synthetic formaldehyde conjugates of DOX, DAU, and EPI, denoted Doxoform (DOXF), Daunoform (DAUF), and Epidoxoform (EPIF), exhibit enhanced toxicity to anthracycline-sensitive and -resistant tumor cells. Uptake and retention of parent anthracycline antitumor drugs (DOX, DAU, and EPI) relative to those of their formaldehyde conjugates (DOXF, DAUF, and EPIF) were assessed by flow cytometry in both drug-sensitive MCF-7 cells and drug-resistant MCF-7/ADR cells. The MCF-7 cells took up more than twice as much drug as the MCF-7/ADR cells, and both cell lines took up substantially more of the formaldehyde conjugates than the parent drugs. Both MCF-7 and MCF-7/ADR cells retained fluorophore from DOXF, DAUF, and EPIF hours after drug removal, while both cell lines almost completely expelled DOX, DAU, and EPI within 1 h. Longer treatment with DOX, DAU, and EPI resulted in modest drug retention in MCF-7 cells following drug removal but poor retention of DOX, DAU, and EPI in MCF-7/ADR cells. Fluorescence microscopy showed that the formaldehyde conjugates targeted the nuclei of both sensitive and resistant cells, and remained in the nucleus hours after drug removal. Experiments in which [(3)H]Doxoform was used, synthesized from doxorubicin and [(3)H]formaldehyde, also indicated that Doxoform targeted the nucleus. Elevated levels of (3)H were observed in DNA isolated from [(3)H]Doxoform-treated MCF-7 and MCF-7/ADR cells relative to controls. The results implicate drug-DNA covalent bonding in the tumor cell toxicity mechanism of these anthracyclines.

Epidoxoform: a hydrolytically more stable anthracycline-formaldehyde conjugate toxic to resistant tumor cells

The recent discovery that the formaldehyde conjugates of doxorubicin and daunorubicin, Doxoform and Daunoform, are cytotoxic to resistant human breast cancer cells prompted the search for hydrolytically more stable anthracycline-formaldehyde conjugates. Doxoform and Daunoform consist of two molecules of the parent drug bound together with three methylene groups, two forming oxazolidine rings and one binding the oxazolidines together at their 3'-amino nitrogens. The 4'-epimer of doxorubicin, epidoxorubicin, reacts with formaldehyde at its amino alcohol functionality to produce a conjugate, Epidoxoform, in 59% yield whose structure consists of two molecules of epidoxorubicin bound together with three methylene groups in a 1, 6-diaza-4,9-dioxabicyclo[4.4.1]undecane ring system. The structure was established from spectroscopic data and is consistent with products from reaction of simpler vicinal trans-amino alcohols with formaldehyde. Epidoxoform hydrolyzes at pH 7.3 to an equilibrium mixture with dimeric and monomeric epidoxorubicin-formaldehyde conjugates without release of formaldehyde or epidoxorubicin. The hydrolysis follows the rate law (A if B) if C + D where A (Epidoxoform) is in rapid equilibrium with B, and B is in slow equilibrium with C and D. The forward rate constant for A/B going to C+D gives a half-life of approximately 2 h at 37 degrees C. At equilibrium the mixture is stable for at least 2 days. At pH 6.0, hydrolysis proceeds with first-order kinetics to epidoxorubicin and formaldehyde with a half-life of 15 min at 37 degrees C. Epidoxoform and epidoxorubicin plus formaldehyde react with the self-complementary DNA octamer (GC)4 to yield five drug-DNA adducts which have structures analogous to the doxorubicin-DNA adducts from reaction of Doxoform with (GC)4. Epidoxoform is 3-fold more toxic to MCF-7 human breast cancer cells and greater than 120-fold more toxic to MCF-7/ADR resistant cells than epidoxorubicin. Epidoxoform in equilibrium with its hydrolysis products is greater than 25-fold more toxic to resistant cells with respect to epidoxorubicin.

Electrostatic and non-electrostatic contributions to the binding free energies of anthracycline antibiotics to DNA

The knowledge about molecular factors driving simple ligand-DNA interactions is still limited. The aim of the present study was to investigate the electrostatic and non-electrostatic contributions to the binding free energies of anthracycline compounds with DNA. Theoretical calculations based on continuum methods (Poisson-Boltzmann and solvent accessible surface area) were performed to estimate the binding free energies of five selected anthracycline ligands (daunomycin, adriamycin, 9-deoxyadriamycin, hydroxyrubicin, and adriamycinone) to DNA. The free energy calculations also took into account the conformational change that DNA undergoes upon ligand binding. This conformational change appeared to be very important for estimating absolute free energies of binding. Our studies revealed that the absolute values of all computed contributions to the binding free energy were quite large compared to the total free energy of binding. However, the sum of these large positive and negative values produced a small negative value of the free energy around -10 kcal/mol. This value is in good agreement with experimental data. Experimental values for relative binding free energies were also reproduced for charged ligands by our calculations. Together, it was found that the driving force for ligand-DNA complex formation is the non-polar interaction between the ligand and DNA even if the ligand is positively charged.

Weekly epidoxorubicin therapy in hormone-refractory metastatic prostate cancer

In a pilot trial, we treated thirty-three hormone resistant metastatic prostate cancer patients with a combination of androgen blockade plus weekly cytotoxic therapy and determined both response and toxicity in 32 of them. Their median Karnofsky performance status at the time of entry was 65. We administered Epidoxorubicin (EpiDx) intravenously, at a dose of 35 mg/m2, every week for 4 months. Initially, all patients had only hormonal therapy and chemotherapy was added once they progressed. In terms of W.H.O. criteria, 9 patients (28%) had a partial response, the disease was stable in 14 (44%), and progressive in 9 (28%); even in this last group, 6 patients with bone metastases experienced lasting relief from pain. No patients had to interrupt treatment due to leukopenia or cardiotoxicity. Other toxicities, including nausea and vomiting, mucositis and alopecia, were mild. Pretreatment prostate-specific antigen (PSA) levels decreased significantly (p < 0.05) in 26 patients (81%) after treatment. In our view, weekly EpiDx administration serves as an active regimen in hormone-refractory prostate cancer.

A new schedule for etoposide, epidoxorubicin and cisplatin with granulocyte colony stimulating factor for advanced gastric cancer: a feasibility study

A new polychemotherapy regimen has been developed for gastric cancer. Etoposide at the dose of 120 mg/m2 for three days, Epidoxorubicin at the dose of 30 mg/m2 on day 1 and Cisplatin at the dose of 40 mg/m2 on day 2 were administered to 26 advanced gastric patients every two weeks with the support of Granulocyte Colony Stimulating Factor from day 8 to day 12 of each cycle. The treatment was feasible with most cases (21/25) having received at least four cycles with a dose intensity > 85%, without life-threatening side effects. Toxicity was lower than that observed in the classical combinations of Etoposide-Anthracycline-Cisplatin.

Drug sensitivity and sequence specificity of human recombinant DNA topoisomerases IIalpha (p170) and IIbeta (p180)

Effective anticancer agents, such as epipodophyllotoxins and anthracyclines, exert their antitumor activity through stabilization of cleavable topoisomerase II/DNA complexes, which may result in DNA breakage on detergent addition. Two isozymes (alpha and beta) of DNA topoisomerase II are present in human cells; however, their roles as drug targets have not been completely defined. We determined the in vitro isoenzyme sensitivities to VM-26 (teniposide) and 4-demethoxy-3'-deamino-3'-hydroxy-4'-epi-doxorubicin (an anthracycline analog) and established the sequence selectivity of isoenzyme-mediated DNA cleavage. Human topoisomerases IIalpha and IIbeta were purified from yeast cells overexpressing the corresponding plasmid-borne cDNA. Enzyme sensitivities to drugs were measured by a DNA cleavage assay using 32P-labeled simian virus 40 DNA fragments, and cleavage sites were mapped using agarose and sequencing gels. Both isozymes were sensitive to the studied poisons. They stimulated similar cleavage intensity patterns in agarose and sequencing gels; however, minor differences could be detected. The results showed that local base preferences for DNA cleavage without drugs were different at positions -2 and -1. On the other hand, sequence specificities of VM-26 and 4-demethoxy-3'-deamino-3'-hydroxy-4'-epi-doxorubicin were identical for both isozymes and corresponded to those of the native murine enzyme. The identical drug sequence specificities suggested that molecular interactions of the tested drugs in the ternary complex are likely similar between the two isozymes. The current findings indicate that both topoisomerase IIalpha and IIbeta may be in vivo targets of antitumor poisons.

P-glycoprotein-mediated efflux of hydroxyrubicin, a neutral anthracycline derivative, in resistant K562 cells

Hydroxyrubin (OH-Dox), a neutral doxorubicin derivative that is only slightly cross-resistant to doxorubicin (Dox), can be actively pumped out of resistant K562 cells by P-glycoprotein (P-gp). This efflux is saturable and can be inhibited by verapamil. The Michaelis constant is equal to 2 +/- 0.5 microM. However, the efficiency of P-gp in pumping out the drugs is 2.5 times less for OH-Dox than for Dox. This shows that in order to be pumped out by P-gp a molecule does not necessarily have to have a basic center. The mean influx coefficient for the drug is 5 times higher for OH-Dox than for Dox. In conclusion, the degree of resistance of analogs is related not only to their ability to be recognized and transported by P-gp but also, and probably essentially, to their kinetics of uptake. Both parameters have to be taken into account in the rational design of new compounds capable of overcoming multidrug resistance.

Overexpression of P-glycoprotein but not its mRNA in multidrug resistant cells selected with hydroxyrubicin

Previous studies have revealed that cultured cells treated with lipophilic natural products containing aromatic rings and basic amino group usually yielded multidrug resistant (MDR) variants. These MDR cells overexpress P-glycoprotein (P-gp), most often due to gene amplification or transcriptional activation of mdr/P-gp genes. Doxorubicin (Dox) is an anthracycline that belongs to this group of compounds. To explore the possible resistance mechanism(s) to anthracyclines that do not involve P-gp, we use a Dox analog, hydroxyrubicin (HyR) or WP159, which contains a C3' hydroxy group in replacement of the amino group in the sugar moiety of Dox thereby reducing basicity and eliminating positive charge in the parental compound to establish HyR-resistant cell lines. These resistant cells displayed the MDR phenotype and overexpressed P-gp as analyzed by Western blot analyses and immunohistochemical staining using two different anti-P-gp antibodies. Strikingly, the levels of P-gp mRNA in the majority of these MDR cells remained comparable to those in the drug-sensitive counterparts by slot blot hybridization. These results implicate that the basic center of the selecting agent is a critical determinant for generating diverse MDR variants, and that HyR may have a posttranscriptional effect on P-gp biosynthesis. This is the first report suggesting that cultured cells exposed to a particular selecting agent may give rise to particular subtype of MDR variants.

Hydroxyrubicin, a deaminated derivative of doxorubicin, inhibits mammalian DNA topoisomerase II and partially circumvents multidrug resistance

In vivo effectiveness of doxorubicin remains restricted due to toxicity and drug resistance. Hydroxyrubicin is a synthetic analog of doxorubicin in which the basic amino group at the C-3' has been replaced by a hydroxyl group in order to overcome recognition by the multidrug resistant (MDR) P-glycoprotein and limit cardiotoxicity. The present study shows that hydroxyrubicin is a less potent intercalator than doxorubicin. Induction of topoisomerase II-mediated DNA cleavage in the human c-myc origin by the two drugs was similar, reaching a maximum at 0.5 microM. Results from the NCI Cell Screening program indicate a relatively good correlation between the cytotoxicity of the 2 drugs on 55 cell lines of various origins (r = 0.723). Using a clonogenic assay, we observed that hydroxyrubicin was 20-fold more cytotoxic against the MDR KB-V1 cell line than doxorubicin and was slightly more cytotoxic than doxorubicin in the sensitive KB3.1 cell line. Uptake studies showed that doxorubicin was retained up to 1 hr in KB3.1 cells and rapidly eliminated from resistant KB-V1 cells. In contrast, hydroxyrubicin was rapidly eliminated from both sensitive KB3.1 and MDR-positive KB-V1 cells. Both drugs induced protein-linked DNA single-strand breaks (SSBs) in both KB3.1 and KB-V1 cells, which is consistent with topoisomerase inhibition. However, the kinetics of DNA SSBs induced by both drugs was very different. DNA breaks disappeared quickly in both KB3.1 and KB-V1 cell lines after hydroxyrubicin removal while DNA breaks induced by doxorubicin disappeared very slowly in KB3.1 cells and rapidly in KB-V1 cells. We conclude that removal of the basic amino group at the C-3' of doxorubicin modifies drug transport and partially circumvents MDR without changing topoisomerase II inhibition when compared with doxorubicin.

A new application for liposomes in cancer therapy. Immunoliposomes bearing enzymes (immuno-enzymosomes) for site-specific activation of prodrugs

We have tested a new type of immunoliposomes which may effectively mediate the targeting of enzymes to be used for site-specific prodrug activation (immuno-enzymosomes). The enzyme beta-glucuronidase, capable of activating the prodrug epirubicin-glucuronide (epi-glu), was coupled to the external surface of immunoliposomes directed towards ovarian cancer cells. A significant increase in cytotoxicity of the prodrug epi-glu was shown when the in vitro cultured cancer cells were pretreated with these immuno-enzymosomes.

Structure-dependent antitumor activities of novel anthracyclines YM1, YM3, YM4 and YM6: drug transport properties and effects on biomacromolecule synthesis in drug sensitive and resistant leukemia cells

The antitumor activities of four novel doxorubicin (DOX) analogues, YM1, YM3, YM4 and YM6 in relation to their structure and drug transport properties, have been investigated in U937 monocytic and CCRF-CEM lymphoid drug sensitive leukemia cell lines, as well as in CEM/VLB100, a drug resistant subline displaying high levels of P-glycoprotein. Treatment of all cell lines with YM1, 3, 4 and 6 produced a dose-dependent decrease in DNA, RNA and protein synthesis as measured by [3H]-thymidine, [3H]-uridine and [3H]-leucine uptake respectively. YM1 was more effective than YM3, YM4 or YM6 against the drug sensitive cells. The antitumor effects of all these DOX-analogues on macromolecule synthesis in U937 and CCRF-CEM cells were lower than that of DOX and epirubicin (EDR). A rapid accumulation of the novel anthracyclines was found in all cell lines compared with DOX or EDR. However, the maximal accumulation of the DOX-analogues was lower than that of EDR. There is a greater efflux from CCRF-CEM sensitive cells and less from CEM/VLB100 resistant cells of the DOX-derivatives when compared with EDR and DOX. Drug-induced cytotoxicity significantly correlated (P < 0.05) with drug retention levels in CCRF-CEM and U937 drug sensitive cells as indicated by an inverse correlation curve between anthracycline retention and drug-induced IC50 value. It was demonstrated that an increased level of drug retained within the sensitive cells would therefore produce a more cytotoxic effect of the drug. However, no such correlation was observed in CEM/VLB100 resistant cells. YM3 was shown to have an increased antitumor activity against CEM/VLB100 resistant cells compared with DOX with a lower resistance factor. These results showed that the antitumor effects of four novel DOX-analogues, like DOX or EDR, were associated with inhibition of DNA replication, transcription and translation. The finding that resistant leukemic cells are more susceptible to the cytotoxic effect of YM3 than DOX warrants further investigation to identify the intrinsic mechanism of resistance.

Removal of the basic center from doxorubicin partially overcomes multidrug resistance and decreases cardiotoxicity

Hydroxyrubicin, a synthetic doxorubicin analog in which the basic amino group at C-3' is replaced by a hydroxyl group, was used as a prototype compound to study the effects of basicity of the sugar moiety on the toxicity and antitumor activity of anthracycline antibiotics. Compared with doxorubicin, hydroxyrubicin showed similar or superior in vitro cytotoxicity against P388, L1210, and M5076 cells, as determined by an MTT assay, and against 8226 and CEM cells, as determined by a growth inhibition assay. Hydroxyrubicin was 5 and 13 times more effective than doxorubicin in inhibiting the growth of multidrug-resistant CEM (CEMvbl) and 8226 (8226R) cells, respectively. Hydroxyrubicin was not cross-resistant with doxorubicin in a cytotoxicity assay against KB 3-1 and KB V1 cells (resistance index 1.1 for hydroxyrubicin versus > 15.6 for doxorubicin). Cellular uptake and retention of hydroxyrubicin were studied by flow cytometry in parent and multidrug-resistant 8226 cells, and compared with those of doxorubicin. In 8226 sensitive cells, 2 h uptake and retention of doxorubicin were similar or higher than those of hydroxyrubicin. In 8226R cells, uptake and retention of hydroxyrubicin were about 3-fold higher than those of doxorubicin. In mice, the acute LD50 of hydroxyrubicin was about 3-fold higher than that of doxorubicin (79.1 versus 25.7 mg/kg). At equitoxic doses, hydroxyrubicin was as myelosuppressive as doxorubicin but less cardiotoxic, as assessed by the Bertazzoli test. In contrast to doxorubicin, hydroxyrubicin, due to the lack of basic amine function, showed no selective interaction with negatively-charged cardiolipin (CL). The observed decrease of affinity to CL might be responsible for the reduced cardiotoxicity of hydroxyrubicin. In in vivo antitumor activity studies, hydroxyrubicin at the optimal dose (37.5 mg/kg, i.p., on day 1) had significant activity against intraperitoneal P388 leukemia resistant to doxorubicin, whereas doxorubicin (10 mg/kg, i.p., on day 1) was inactive (%T/C 163-200 versus 118-120). These studies indicate that: (i) the amino group at position 3' is not essential for doxorubicin to exert its biological activity, (ii) removal of the basic center (deamination at the C-3') results in an increased cellular uptake and retention, (iii) the increased cellular uptake and retention of hydroxyrubicin in multidrug-resistant cells correlate with a partial or total lack of cross-resistance of this analog with the parent compound, doxorubicin, and (iv) deamination at position 3' confers a reduced cardiotoxicity and diminished affinity for CL.

Evaluation of the in vitro antiproliferative properties of four novel anthracyclines YM1, 3, 4 and 6 in human leukemia cell lines

The antitumor activity of novel doxorubicin analogues YM1, YM3, YM4 and YM6 was evaluated against drug sensitive U937 monocytic leukemia and CCRF-CEM lymphoid leukemia cell lines, as well as drug resistant CEM/VLB100 lymphoid multidrug resistant leukemia cell line by a [3H]thymidine incorporation assay. Different antileukemic activities of these new anthracyclines were observed in our studies. These novel anthracyclines produced a dose- and time-dependent inhibition in all the leukemic cell lines tested, while YM1 and YM3 were more effective than YM4 and YM6 against all the leukemic cell lines. The antitumor activity of all these novel analogues was lower than that of doxorubicin or epidoxorubicin in drug sensitive leukemic cells. The relative resistance values (IC50 of resistant cell line/IC50 of sensitive parental cell line) of YM1, 3, 4 and 6 were 27, 7, 5 and 14 respectively. These were lower than the resistance values for ADM and EDR which were 45 and 40 respectively. YM3 had a similar antileukemic activity against the CEM/VLB100 drug resistant leukemic cell line to ADM or EDR with a lower relative resistance value and a slightly increased IC50 value. Our results suggest that YM3 may be used in high dose for the clinical treatment of leukemias with possible less cardiotoxicity as well as less drug resistance.

Measurement of epidoxorubicin and its metabolites by high-performance liquid chromatography using an advanced automated sample processor

A sensitive and rapid method for measuring epidoxorubicin and its six metabolites by high-performance liquid chromatography using an advanced automated sample processor is described. Plasma samples (1 ml) were extracted using C2 cassettes, and reversed-phase chromatography was performed with an Apex II ODS column. The isocratic mobile phase of acetonitrile-0.019 M NaH2PO4 (pH 4.0) had a flow-rate of 1 ml/min and the fluorescence detector an excitation wavelength of 480 nm with an emission at 580 nm. Linear calibration curves were obtained which were reproducible both within-day and day-to-day (coefficients of variation less than 10%). The extraction efficacy of epidoxorubicin was 88% and ranged from 51 to 88% for the metabolites. This method has been successfully applied to measure the plasma levels of these compounds in patients receiving epidoxorubicin over a wide dose range (12-120 mg/m2) and in patients with disturbed liver biochemistry.

Comparative activity of anthracycline 13-dihydrometabolites against rat glioblastoma cells in culture

We have studied the growth inhibition, DNA synthesis inhibition and cell incorporation of five 13-dihydrometabolites of anthracyclines in a model of doxorubicin-sensitive and -resistant rat C6 glioblastoma cells. These compounds were major metabolites for doxorubicin, epirubicin, daunorubicin, idarubicin and the new anthracycline 4'-deoxy-4'-iododoxorubicin and are known to be present in appreciable amounts in the plasma of patients treated with these drugs. We have shown that in vitro growth inhibition in sensitive cells was either much lower than that of the parent drug (doxorubicinol, epirubicinol, daunorubicinol), or similar to it (idarubicinol, 4'-iodoxorubicinol). In resistant cells, growth inhibition was about 100 times lower than in wild cells, and was always lower than that of the parent anthracycline. DNA synthesis inhibition occurred in sensitive cells for doses about 100 times higher than those required for growth inhibition, but in resistant cells, similar doses provided growth inhibition and DNA synthesis inhibition. Metabolite incorporation was always lower than that of the corresponding parent anthracycline; it was greatly reduced in resistant cells as compared to sensitive ones. The calculated intracellular concentrations obtained for the same growth inhibition are higher in resistant cells than in sensitive cells; in contrast, the calculated intracellular concentrations obtained for the same DNA synthesis inhibition are similar in resistant and sensitive cells, and similar for all the metabolites studied. These results suggest that the amount of drug incorporated is primarily responsible for DNA synthesis inhibition, which is directly correlated to growth inhibition in resistant cells, but not in sensitive cells.

Synthesis and antitumor activity of 3'-deamino-3'-hydroxydoxorubicin. A facile procedure for the preparation of doxorubicin analogs

Two successful routes have been developed for preparation of 3'-deamino-3'-hydroxydoxorubicin (11), based on protection of the 14-hydroxyl group of the aglycon by using tert-butylchlorodimethylsilane. The key intermediate, 14-O-tert-butyldimethylsilyl-7-O-(3,4-di-O-acetyl-2,6-dideoxy-alpha-L-ly xo -hexopyranosyl)adriamycinone (9), was successively deacetylated and desilylated in high yield to give the desired product 11. This route constitutes a general method of access to glycon-modified doxorubicin analogs. Compound 11 showed high antitumor activity in vivo in the murine P388 lymphocytic leukemia assay.

3'-Deamino-4'-epi-3'-hydroxy-daunorubicin and -doxorubicin. Synthesis and antitumor activity

3'-Deamino-4'-epi-3'-hydroxy-daunorubicin (11) and -doxorubicin (14) have been synthesized. In the in vivo murine P-388 lymphocytic leukemia assay, these two compounds were more active than daunorubicin (1) and doxorubicin (2), respectively. Comparative studies in the P-388 assay indicated 3'-deamino-3'-hydroxydoxorubicin (3) to be more active than its 4'-epimer 14.