Mitochondria organelle transplantation: introduction of normal epithelial mitochondria into human cancer cells inhibits proliferation and increases drug sensitivity.

Mitochondrial dysfunction of cancer cells includes increased aerobic glycolysis, elevated levels of ROS, decreased apoptosis, and resistance to chemotherapeutic agents. We hypothesized that the introduction of normal mitochondria into cancer cells might restore mitochondrial function and inhibit cancer cell growth, and reverse chemoresistance. First, in the present study, we tested if mitochondria of immortalized, untransformed mammary epithelial MCF-12A cells could enter into human cancer cell lines. Second, if introducing normal mitochondria into cancer cells would inhibit proliferation. And third, would the addition of normal mitochondria increase the sensitivity of human breast cancer MCF-7 cells to chemotherapy. We found that JC-1-stained mitochondria of immortalized, untransformed mammary epithelial MCF-12A cells can enter into the cancer cell lines MCF-7, MDA-MB-231, and NCI/ADR-Res, but cannot enter immortalized, untransformed MCF-12A cells. The normal mitochondria from immortalized, untransformed MCF-12A cells suppressed the proliferation of MCF-7 and NCI/ADR-Res cells in a dose-dependent pattern, but did not affect the proliferation of immortalized, untransformed MCF-12A cells. The normal mitochondria from immortalized, untransformed MCF-12A cells increased the sensitivity of human breast cancer MCF-7 cells to doxorubicin, Abraxane, and carboplatin. In conclusion, the introduction of normal mammary mitochondria into human breast cancer cells inhibits cancer cell proliferation and increases the sensitivity of the MCF-7 human breast cancer cell line to doxorubicin, Abraxane, and carboplatin. These results support the role of mitochondrial dysfunction in cancer and suggest the possible use of targeted mitochondria for cancer therapeutics.

Accelerated partial breast irradiation: initial experience with the Intrabeam System.

Failure after breast conserving surgery (BCS) and total breast irradiation usually occurs at the site of the original tumor. This has caused an increased interest in accelerated partial breast irradiation (APBI), because if radiation is delivered directly to the tumor bed there should be better local control. Patients greater than age 50 with core biopsy confirmed invasive ductal carcinoma were enrolled. They had preoperative ultrasound defining margins of less than 3.5 cm. Intraoperative ultrasound was also performed in an effort to ensure good surgical margins. After excision of the tumor, intraoperative radiotherapy (IORT) with the Intrabeam System was delivered to the tumor bed. The procedure has been performed on 67 patients. Sixty-one patients had it with the original surgery, while 6 had the procedure after re-exploration of the segmental mastectomy site. Because of the final pathology (surgical margins, tumor biology, and nodal status) 4 patients later had total mastectomy and 11 received total breast irradiation. When total breast irradiation is done the IORT serves as the radiation boost. The cosmetic results have been good to excellent, and there have been no serious surgical or radiation complications. To date there have been no local failures. IORT with the Intrabeam System is feasible, user friendly, versatile, with few complications, good cosmetic results, and great patient acceptance. It is practical and excellent for breast IORT in the community setting.

The crystal structure of nucleoplasmin-core: implications for histone binding and nucleosome assembly.

The efficient assembly of histone complexes and nucleosomes requires the participation of molecular chaperones. Currently, there is a paucity of data on their mechanism of action. We now present the structure of an N-terminal domain of nucleoplasmin (Np-core) at 2.3 A resolution. The Np-core monomer is an eight-stranded beta barrel that fits snugly within a stable pentamer. In the crystal, two pentamers associate to form a decamer. We show that both Np and Np-core are competent to assemble large complexes that contain the four core histones. Further experiments and modeling suggest that these complexes each contain five histone octamers which dock to a central Np decamer. This work has important ramifications for models of histone storage, sperm chromatin decondensation, and nucleosome assembly.

Inhibition of growth of human breast carcinoma cells by an antisense oligonucleotide targeted to the transferrin receptor gene.

Transferrin receptor expression is controlled by the amount of iron required by the cell to maintain its metabolism and therefore tumor cells in a highly proliferative state have a high density of transferrin receptors. In this study, phosphorothioated antisense TfR oligonucleotides (TfR-ODna) targeted to the sequences of TfR mRNA including the AUG initiation codon and the control sense chain (TfR-ODns) were synthesized. The rate of cellular DNA synthesis was determined by [3H]-thymidine incorporation. Administering TfR-ODna to three morphologically distinct breast cancer cell lines (MCF-7, T47D, and MDA-MB-231) and a normal breast cell line (MCF-12A) caused specific inhibition of tumor cell growth. The IC50 (50% inhibition of DNA synthesis) of the TfR-ODna for the MCF-7, T47D and MDA-MB-231 cells were 0.5, 0.5, and 1.0 microM, respectively, whereas the MCF-12A normal breast cells were about 30 times (IC50 of 30 microM) less sensitive to TfR-ODna than the breast cancer cells. The cytotoxicity of the antisense TfR-ODna was 10 to 60 times greater than that of the sense chain (TfR-ODns). TfR mRNA and protein synthesis were demonstrated by RT-PCR and immunohistochemical staining, respectively. Approximately 50% inhibition of the expression of TfR mRNA was observed when breast cancer cells were treated with 1 microM antisense TfR ODNa for 72 hrs but 1 microM antisense only caused 14% inhibition in normal breast cells. The decreased cytotoxicity and inhibition of TfR gene expression when the tumor cells were treated with the same concentration (1 microM) of TfR-ODns demonstrated the specificity of the TfR-ODna for blocking the target TfR gene. The combined cytotoxicities to human breast tumor MCF-7 cells of the antisense TfR-ODna and the iron chelator deferoxamine (DFO) or the ribonucleotide reductase inhibitor hydroxyurea were observed in this study. IC50s (50% inhibition of DNA synthesis) for DFO and hydroxyurea individually were 0.3 microM and 250 microM, respectively. The CalcuSyn program was used to determine the combined effects among the agents and synergism (Combined Indexes (CI) < 1) were found with the following two combinations: TfR-ODna (0.007 microM to 0.15 microM) with DFO (0.15 microM to 5 microM) and TfR-ODna (0.007 microM to 0.15 microM) with hydroxyurea (50 microM to 800 microM). However, inhibition by TfR-ODns was not synergistic with either DFO or hydroxyurea. The synergistic effects on inhibition of DNA synthesis between TfR-ODna and DFO or hydroxyurea suggest that inhibition of breast cancer cell growth by TfR-ODna is produced by depletion of iron pools that are required for DNA synthesis in tumor cells. The fact that TfR-ODna specifically decreases cell viability and proliferation, and reduces TfR mRNA and protein expression in human breast carcinoma cells without affecting normal breast cells, suggests that the antisense oligonucleotide to the transferrin receptor may be a novel therapeutic approach in breast cancer.

The crystal structure of MarR, a regulator of multiple antibiotic resistance, at 2.3 A resolution.

MarR is a regulator of multiple antibiotic resistance in Escherichia coli. It is the prototypical member of the MarR family of regulatory proteins found in bacteria and archaea that play important roles in the development of antibiotic resistance, a global health problem. Here we describe the crystal structure of the MarR protein, determined at a resolution of 2.3 A. This is the first reported crystal structure of a member of this newly-described protein family. The structure shows MarR as a dimer with each subunit containing a winged-helix DNA binding motif.

Expression of transferrin receptor and ferritin H-chain mRNA are associated with clinical and histopathological prognostic indicators in breast cancer.

It is well known that iron plays an essential role in many biochemical reactions and that rapidly growing cells require more iron for their growth and metabolism than resting cells. Transferrin and its receptor are required for entry of iron into the cell. In contrast, ferritin is a cellular storage protein whose main function is to sequester excess ferric iron and thus prevent high concentrations of soluble ferric iron from becoming toxic to the cell. However, the clinical significance of both transferrin receptor and ferritin mRNA levels have not previously been described in tumors from breast cancer patients. In this study, tumor tissue mRNA levels of transferrin receptor and ferritin were quantitated on forty-two breast cancer patients. A highly sensitive non-radioisotopic cDNA polymerase chain reaction assay was used to quantitate expression of mRNA. The expression of glyceraldehyde-3-phosphate dehydrogenase served as the control. In the tumor tissue from the 42 breast cancer patients the transferrin receptor mRNA levels were significantly correlated to the ferritin H-chain mRNA levels (Spearman correlation r = 0.5433, p = 0.0002; Pearson correlation r = 0.6276, p < 0.0001). The level of amplified transferrin receptor complementary DNA was related to differentiation (ANOVA, p = 0.042) with poorly differentiated tumors having high levels of transferrin receptor mRNA. Further, the levels of amplified gene for ferritin heavy chain complementary DNA was directly related to axillary lymph nodes status (Student's t-test, p = 0.044), presence of metastatic disease (Student's t-test, p = 0.046) and clinical stage (stage I + stage II versus stage III + stage IV; Student's t-test, p = 0.0181). These results demonstrate that non-radioisotopic RT-PCR is a very sensitive method for determining mRNA levels in tumor tissue. Additionally, the quantitation of expression of transferrin receptor and ferritin heavy chain mRNA may be useful for assessing prognosis and guiding therapeutic decisions in breast cancer patients.

Reduction in serum IL-6 after vacination of breast cancer patients with tumour-associated antigens is related to estrogen receptor status.

Elevated serum IL-6 concentrations have been associated with poor prognosis in a variety of cancers, and decreases in serum IL-6 concentrations have been reported after chemotherapy. We have demonstrated that serum IL-6 concentrations are elevated in breast cancer patients [normal women 0.7 +/- 2.5 pg/ml (n=36), breast cancer patients 38.3 +/- 138.7 pg/ml (n = 111)]. After vaccination of breast cancer patients with a combination of tumour-associated antigens and biological adjuvants (IL-2 and GM-CSF), the concentration of IL-6 decreased significantly (P<0.05) to 8.1 +/- 14.6 pg/ml (n=85). Other studies have shown that oestrogen suppresses IL-6 production in oestrogen receptor positive breast cancer cells. We have demonstrated that the decrease in IL-6 associated with vaccination is related to the oestrogen receptor status of the tumours from breast cancer patients, as a decrease in IL-6 from 124.0 +/- 267.5 pg/ml (n=26) to 6.2 +/- 11.0 pg/ml (n=34) only occurs in patients with oestrogen receptor negative tumours. The IL-6 concentration in breast cancer patients with oestrogen receptor positive tumours remained unchanged (9.5 pg/ml before vaccination, and 9.3 pg/ml after vaccination). These results suggest that postmenopausal women with oestrogen receptor negative breast cancers, who do not respond well to either hormonal therapy with tamoxifen or adjuvant chemotherapy, may have a significant response to vaccination with autologous tumour-associated antigens.

The crystal structure of the photoprotein aequorin at 2.3 A resolution.

Aequorin is a calcium-sensitive photoprotein originally obtained from the jellyfish Aequorea aequorea. Because it has a high sensitivity to calcium ions and is biologically harmless, aequorin is widely used as a probe to monitor intracellular levels of free calcium. The aequorin molecule contains four helix-loop-helix 'EF-hand' domains, of which three can bind calcium. The molecule also contains coelenterazine as its chromophoric ligand. When calcium is added, the protein complex decomposes into apoaequorin, coelenteramide and CO2, accompanied by the emission of light. Apoaequorin can be regenerated into active aequorin in the absence of calcium by incubation with coelenterazine, oxygen and a thiol agent. Cloning and expression of the complementary DNA for aequorin were first reported in 1985 (refs 2, 6), and growth of crystals of the recombinant protein has been described; however, techniques have only recently been developed to prepare recombinant aequorin of the highest purity, permitting a full crystallographic study. Here we report the structure of recombinant aequorin determined by X-ray crystallography. Aequorin is found to be a globular molecule containing a hydrophobic core cavity that accommodates the ligand coelenterazine-2-hydroperoxide. The structure shows protein components stabilizing the peroxide and suggests a mechanism by which calcium activation may occur.

Doxorubicin-gallium-transferrin conjugate overcomes multidrug resistance: evidence for drug accumulation in the nucleus of drug resistant MCF-7/ADR cells.

Development of multidrug resistance (MDR) in cancer cells decreases net doxorubicin (ADR) uptake as a result of increased efflux, increased intracellular sequestration, and decreased membrane permeability. In this study, we investigated whether conjugation of ADR to transferrin (Tf) could overcome MDR in breast cancer cells. The multidrug resistant MCF-7/ADR breast cancer cell line was over 1000-fold more resistant to ADR, than its parental MCF-7 cell line, as determined by 3[H]-thymidine assay. The MCF-7/ADR cell line also expressed both MDR1 and MRP genes, as detected by RT-PCR. The ADR was coupled using a glutaraldehyde technique to human transferrin saturated with either ferric chloride (Fe-Tf) or gallium nitrate (Ga-Tf). These conjugates were tested for cytotoxicity on both MCF-7 and MCF-7/ADR cells after 6 days of incubation. The doxorubicin-gallium-transferrin conjugate (ADR-Ga-Tf) exhibited approximately the same inhibitory effect as ADR on MCF-7 cells with IC50s of 2.34 x 10(-3) microM and 1.42 x 10(-3) microM, respectively. However in MCF-7/ADR cells ADR-Ga-Tf reversed resistance to free ADR and decreased 100-fold the IC50 from 8.98 microM with free ADR to 9.52 x 10(-2) microM. ADR-Fe-Tf was 10-fold more inhibitory to MCF-7/ADR cells than free ADR. Compared to Ga-Tf, ADR-Ga-Tf was 500- and 3000-fold more inhibitory to MCF-7 and MCF-7/ADR cells, respectively. These results demonstrated that ADR-Ga-Tf reverses resistance to free ADR and Ga-Tf in MCF-7/ADR cells. The distribution of ADR in both cell lines was examined by fluorescence microscopy. It was noted that ADR mainly accumulated in the cytoplasm around the nucleus in MCF-7/ADR cells, but in both the cytoplasm and nucleus of MCF-7 cells. However the conjugate of ADR-Ga-Tf allowed ADR to accumulate in the cytoplasm and nucleus of both the MCF-7/ADR and MCF-7 cells. Further investigation of MDR1 and MRP genes expression by RT-PCR demonstrated that Ga-Tf decreased expression of the MRP more than the MDR1 gene. Therefore the reversal of resistance to ADR by the ADR-Ga-Tf conjugate is mediated by the transferrin receptor transmembrane transport mechanism, redistribution of ADR into the nucleus of ADR resistant MCF-7/ADR cells and inhibition of MRP gene expression.

Vaccination with a mixed vaccine of autogenous and allogeneic breast cancer cells and tumor associated antigens CA15-3, CEA and CA125--results in immune and clinical responses in breast cancer patients.

In breast cancer there is often overexpression of the breast cancer antigen CA15-3, the carcinoembryonic antigen (CEA) and the ovarian cancer antigen CA125, which makes them potential target antigens for immunotherapy. In this study, we used a multi-antigen vaccine, which included the following antigens: autologous breast cancer cells (AUTOC), allogeneic breast cancer MCF-7 cells (ALLOC), and the tumor associated antigens CA15-3, CEA and CA125, plus low doses of granulocyte/macrophage-colony-stimulating factor (GM-CSF) and interleukin 2 (IL-2). Forty-two breast cancer patients received weekly subcutaneous vaccination at the 1st, 2nd, 3rd, 7th, 11th and 15th weeks. Their lymphocyte proliferative responses to AUTOC, ALLOC, CA15-3, CEA and CA125 were tested in lymphocyte blastogenesis assays (LBA) before and after vaccination. The disease stage and serum CA15-3, CEA and CA125 concentrations were also determined pre- and post-vaccination. We found that the vaccine was safe, and the only major side effects were swelling at the site of injection, muscle pain, and weakness or fatigue. The vaccine induced a significant increase in post-vaccination lymphocyte proliferative responses to AUTOC, CA15-3, CEA and CA125 but not ALLOC, compared to pre-vaccination (p < 0.05, p < 0.01, p < 0.05, p < 0.01 and p > 0.05, respectively, a paired t Test). Computed tomography (CT), ultrasound or bone scan showed evidence of disease improvement in 2 (12%) patients after vaccination. Hepatic metastases were reduced in size and number and some actually disappeared one patient. Metastatic disease in the L5 vertebra and the skull decreased in size and some osteolytic sites completely healed in a second patient. In addition, 7 patients (44%) had stable disease and 7 patients (44%) had disease progression. We did not find vaccination significantly reduced serum tumor markers CA15-3, CEA and CA125 of these breast cancer patients. These results suggest that the vaccine mixture of autologous and allogeneic breast cancer cells and tumor associated antigens plus GM-CSF and IL-2 can be administered safely to breast cancer patients and there is evidence for improved immunity and clinical efficacy.

Inhibitory effect of deferoxamine mesylate and low iron diet on the 13762NF rat mammary adenocarcinoma.

The iron chelator deferoxamine mesylate has been shown to inhibit the growth of a variety of human malignant cell lines and the rat 13762NF mammary adenocarcinoma cell line. In vivo studies in mice have also demonstrated that an iron deficiency induced by either feeding a low iron diet or injecting the iron chelator deferoxamine mesylate decreases tumor growth. In this study Fisher rats were transplanted with the 13762NF mammary adenocarcinoma and divided into four groups: normal diet, normal diet plus deferoxamine mesylate treatment, low iron diet and low iron diet plus deferoxamine mesylate treatment. The measurements of tumor size and body weight were recorded weekly. We found that treatment with either deferoxamine mesylate or a low iron diet decreased rat tumor growth, but the greatest inhibitory effect on tumor growth occurred when the rats were treated with deferoxamine mesylate injections plus fed a low iron diet. These treatments did not significantly inhibit the weight gain of the rats. At the end of the experiments measurement of serum iron proved that these treatments caused iron deficiency, but there was no significant treatment related alteration in blood hematocrit. We therefore concluded that deferoxamine mesylate may be a useful chemotherapeutic agent in the treatment of breast cancer, when used in combination with standard chemotherapeutic regiments or with other agents that interfere with iron metabolism, and further that the restricting of iron intake should be considered when planning chemotherapy for all cancer patients.

Mutational and crystallographic analyses of interfacial residues in annexin V suggest direct interactions with phospholipid membrane components.

Annexin V belongs to a family of eukaryotic calcium-dependent membrane-binding proteins. The calcium-binding sites at the annexin-membrane interface have been investigated in some detail; however, little is known about the functional roles of highly conserved interfacial residues that do not coordinate calcium themselves. In the present study, the importance of tryptophan 185, and threonine or serine at positions 72, 144, 228, and 303, in rat annexin V is investigated by site-directed mutagenesis, X-ray crystallography, and functional assays. The high-resolution crystal structures of the mutants show that the mutations do not cause structural perturbations of the annexin molecule itself or disappearance of bound calcium ions from calcium-binding sites. The assays indicate that relative to wild-type annexin V, loss of the methyl substituent at position 72 (Thr72-->Ser) has no effect while loss of the hydroxyl group (Thr72-->Ala or Thr72-->Lys) causes reduction of membrane binding. Multiple lysine substitutions (e.g., Thr72,Ser144,Ser228,Ser303-->Lys) have a greater adverse effect than the single lysine mutation, suggesting that in annexin V the introduction of potentially favorable electrostatic interactions between the lysine side chains and the net negatively charged membrane surface is not sufficient to overcome the loss of the hydroxyl side chains. Replacement of the unique tryptophan, Trp185, by alanine similarly decreases membrane binding affinity. Taken together, the data suggest that the side chains mutated in this study contribute to phospholipid binding and participate directly in intermolecular contacts with phospholipid membrane components.

Antineoplastic drugs that interfere with iron metabolism in cancer cells.

Normal iron metabolism can be perturbed with iron chelators, toxic metals that bind to transferrin, toxic metals bound to transferrin or antineoplastic agents covalently linked to transferrin. These agents cause significant inhibition of tumor cell growth in cell culture and have been shown to have significant in vivo antineoplastic activity. Cell culture studies showed that deferoxamine mesylate inhibits cell growth and division in both the MCF-7 human breast and HeLa human cervical carcinoma cell lines. Animal studies demonstrated that when deferoxamine mesylate is injected intravenously into rats that are on a low iron diet, there is a significant reduction in the growth of 13762NF mammary adenocarcinomas. Gallium, indium and the antineoplastic agent cisplatin were bound to the iron binding site of transferrin and inhibit the growth of malignant carcinoma cell lines. Gallium-transferrin and indium-transferrin were at least 10 times more inhibitory to both MCF-7 and HeLa cell lines than their free salts. Further cell culture studies demonstrated that cisplatin-transferrin complexes act synergistically with doxorubicin to inhibit the growth of cultured MCF-7 cells. In a Phase I clinical trial of cisplatin-transferrin complex there was a 36% (four of 11 patients) response rate in breast cancer patients with advanced disease. In a second clinical study the sequential administration of deferoxamine mesylate (2 days at 6 g/day in 8 hrs), cisplatin-transferrin complex (7 days at 500 mg/day) and FAC (5-fluorouracil, doxorubicin and cyclophosphamide at 450, 45 and 450 mg/m2, respectively) to advanced breast cancer patients resulted in partial responses in seven of eight patients treated. Future work will concentrate on substituting transferrin based agents with daunorubicin or doxorubicin attached to the surface of the transferrin, and gallium or indium bound to the iron binding site, to increase efficacy of the second component of the sequential combination chemotherapy.

Stereotaxic localization and core needle biopsy of nonpalpable breast lesions: two-year follow-up of a prospective study.

In August 1989, we began a prospective study of patients with abnormal mammograms to determine the clinical efficacy of stereotaxic localization and needle biopsy of nonpalpable breast lesions. By August 1990, 115 patients had undergone stereotaxic localization and needle biopsy of nonpalpable breast lesions using the Mammotest II (Fischer Imaging, Denver, CO) and an 18-gauge needle in a Bard Biopty gun (Bard Urological, Covington, GA). In 19 per cent (22 of 115) of the cases, the pathologist suggested open surgical biopsies of the lesions due to clinical judgment, or atypical or cancer cells in the core biopsy specimen. Of these 22 cases, 12 (54%) were found to be cancer on open surgical biopsy--10 per cent of all the patients. Of the remaining 93 patients with benign pathology, 9 were lost to follow-up by the end of the second year after closure of the study. The remaining 84 patients were followed by mammography and physical exam at 3 months, at 12 months, and yearly thereafter to determine whether cancer had been missed or developed at the biopsy site. The median follow-up was 24 months (mean, 23.3 months), and all 84 patients were found to have no evidence of malignant disease at follow-up. The small group (10 cases) of patients who were determined to have benign disease by open surgical biopsy were also found on follow-up to have no evidence of malignant disease (median follow-up, 20.5 months; and mean, 18.3 months). The accuracy of this stereotaxic procedure, combined with an approximately 80 per cent decrease in the more expensive and more invasive open surgical biopsy procedure, provides strong support for the use of this procedure on all nonpalpable breast lesions that would normally proceed to open surgical biopsy.