Tumor therapy with targeted atomic nanogenerators.

A single, high linear energy transfer alpha particle can kill a target cell. We have developed methods to target molecular-sized generators of alpha-emitting isotope cascades to the inside of cancer cells using actinium-225 coupled to internalizing monoclonal antibodies. In vitro, these constructs specifically killed leukemia, lymphoma, breast, ovarian, neuroblastoma, and prostate cancer cells at becquerel (picocurie) levels. Injection of single doses of the constructs at kilobecquerel (nanocurie) levels into mice bearing solid prostate carcinoma or disseminated human lymphoma induced tumor regression and prolonged survival, without toxicity, in a substantial fraction of animals. Nanogenerators targeting a wide variety of cancers may be possible.

Antitumor activity of actinonin in vitro and in vivo.

Actinonin, an antibiotic and CD13/aminopeptidase N (APN) inhibitor, has been shown to be cytotoxic to tumor cell lines in vitro. We investigated the antiproliferative effects of actinonin on human and murine leukemia and lymphoma cells. Actinonin inhibited growth of NB4 and HL60 human cell lines and AKR mouse leukemia cells in vitro with an IC50 of about 2-5 micrograms/ml. The inhibitory effect on CD13-positive cells was not blocked by pretreatment with the anti-CD13/APN monoclonal antibody F23, which binds with high affinity to the active site of CD13/APN and blocks its enzymatic activity. Moreover, F23 alone was not inhibitory to CD13-positive cells. Furthermore, a similar inhibitory IC50 of actinonin was seen in the CD13-negative cell lines RAJI and DAUDI human lymphoma. These data suggest that the inhibitory effect of actinonin is not mediated by inhibition of CD13/APN. Cell cycle analysis showed that actinonin induces a G1 arrest in HL60 and NB4 cells; apoptosis was observed in 20-35% of the cells as measured by intracellular flow cytometry. To assess whether these effects could be seen in vivo, the effect of actinonin on the syngeneic AKR mouse leukemia model was evaluated. Actinonin showed dose-dependent antitumor effects on AKR leukemia in vivo, resulting in a survival advantage. In conclusion, apoptosis, growth inhibition, and therapeutic effects in vivo are induced by actinonin and are not likely to be mediated by CD13/APN.

Detection of Neospora from tissues of experimentally infected rhesus macaques by PCR and specific DNA probe hybridization.

Neospora is a newly recognized Toxoplasma-like cyst-forming coccidian parasite that causes abortion or congenital infections in naturally or experimentally infected animals. In this study, pregnant rhesus macaques were inoculated with culture-derived tachyzoites of a bovine Neospora isolate, and tissue samples from various major organs were collected from dams and fetuses for the detection of parasite DNA by using oligonucleotide primers COC-1 and COC-2 for PCR amplification of a conserved coccidial nuclear small-subunit rRNA gene sequence, and amplification products were confirmed by hybridization with a Neospora-specific DNA probe. PCR products were amplified from DNAs of different fetal monkey tissues, including brain, heart, lung, liver, spleen, skeletal muscle, skin, and placenta. In addition, Neospora DNA was amplified from the brain, heart, and lung tissues of infected rhesus macaque dams. The PCR and probe hybridization system may provide an effective method for the detection of Neospora infection in fetuses and dams from nonhuman primates and may be useful in determining the zoonotic potential of Neospora.

Interleukin-2 enhancement of cytotoxicity by humanized monoclonal antibody M195 (anti-CD33) in myelogenous leukemia.

Humanized M195 (HuM195) is a genetically engineered, human IgG1 version of the parent M195, a mouse immunoglobulin G2a, anti-CD33 monoclonal antibody which reacts with early myeloid progenitor cells and myelogenous leukemia cells. In Phase I studies in patients with relapsed and refractory myelogenous leukemia, HuM195 safely targeted to sites of disease and was nonimmunogenic. HuM195 shows only modest capability of antibody-dependent cellular cytotoxicity (ADCC) against target HL60 cells and minimal cytolytic activity mediated by human complement. Therefore, efforts were made to enhance ADCC using cytokines. gamma-Interferon, granulocyte-macrophage colony-stimulating factor, and granulocyte colony-stimulating factor did not promote neutrophil-mediated ADCC with HuM195. However, interleukin-2 (IL-2) showed a range of 2-6-fold increases in ADCC against fresh myelogenous leukemia cells and HL60 cells over that seen with HuM195 or low-dose IL-2 alone. ADCC potency was not improved further by the use of homodimeric HuM195. Flow cytometry and Fc receptor-blocking experiments showed that CD16(+) cells were essential for IL-2-enhanced ADCC. As compared to HL60 cells, a multidrug-resistant line of HL60 cells was at least as susceptible to killing by IL-2 or HuM195 or in combination, suggesting that the mechanism of killing may be active against cells surviving and resistant to chemotherapy. Since these in vitro levels of IL-2 and HuM195 can be safely achieved in patients, the enhancement of HuM195 ADCC with low-dose IL-2 is a possible strategy that may be used in vivo to eliminate minimal disease in future trials of patients with myeloid leukemias.

Dietary Platycladus orientalis seed oil suppresses anti-erythrocyte autoantibodies and prolongs survival of NZB mice.

Dietary fish oils rich in 20:5(5,8,11,14,17) and 22:6(4,7,10,13,16,19) are known to replace arachidonic acid [20:4(5,8,11,14)] and to improve the immunopathology of New Zealand mice. However, in humans, similar dietary strategies may be impractical because of the high levels of fish oils required. In contrast, we believe that beneficial effects in humans may be attainable using new exotic fatty acids. Toward this end, we have focused on 5,11,14-eicosatrienoic acid [5,11,14-ETA, 20:3(5,11,14)]. This fatty acid is structurally analogous to 20:4(5,8,11,14) but lacks the delta-8 double bond essential for conversion to eicosanoids. To examine our hypothesis, diets containing the oil of Platycladus orientalis containing 3% 5,11,14-ETA, a matched control oil, fish oil, or safflower oil were fed to NZB mice. There was a dramatic delay in both the onset and the titer of direct Coombs' tests in mice fed P. orientalis oil. These were directly reflected by the abundance of 5,11,14-ETA in serum lipids. Most striking was the accumulation of 5,11,14-ETA in serum and tissue phospholipids. Though constituting only 3% of dietary fatty acids, 5,11,14-ETA was the most abundant long chain polyunsaturated fatty acid in the serum phospholipids, suggesting that it very successfully competed with 20:4 as a constituent of membrane lipids. 5,11,14-ETA was incorporated into all tissue phospholipids examined except brain phosphatidyl inositol. Among tissues, liver showed the highest incorporation of 5,11,14-ETA into phosphatidylcholine (PC), phosphatidylserine (PS), and phosphatidylinositol (PI), yet spleen PE had a higher quantity of ETA than other tissues. Lesser arachidonate in spleen PS, heart PC, and heart PI showed the evidence of replacement by 5,11,14-ETA. The data presented illustrates how new nutrition can modify autoimmune responses and emphasizes the need for further studies based on new nutritional strategies.

Value of plasma alpha-1-acid glycoprotein assay in the detection of human colorectal cancer: comparison with carcinoembryonic antigen.

Plasma specimens assessed by caracinoembryonic antigen (CEA) in the clinical laboratory for the detection of colorectal cancer were simultaneously assayed in our laboratory for alpha-1-acid glycoprotein (alpha 1AG), by means of a solid-phase enzyme-linked immunosorbent assay we developed. In 28 patients with colorectal cancer of Dukes A, B, and C classes, elevated levels of alpha 1AG were seen in 12 and of CEA in 8. In 44 patients with distant metastasis (Dukes D lesions), elevated plasma levels of alpha 1AG were seen in 29 and of CEA in 34. No statistical differences in the detection rate were found among these markers in these 2 groups of patients. In 33 cases of non-neoplastic disease involving the large bowel, elevated plasma levels of alpha 1AG were seen in 6, and elevated CEA levels were seen in 7. There was no statistical difference of false positive rates among ;these two markers. Elevated plasma levels of either CEA or alpha 1AG were found in 57 cases of colorectal cancer. This preliminary study suggests that the sensitivity of the plasma alpha 1AG assay is similar to that of the CEA assay in the detection of colorectal cancer. The combination of these two assays increases the detection rate of colorectal cancer significantly.

Plasma alpha 1-acid glycoprotein levels in pregnancy.

One hundred and five determinations of plasma alpha 1-acid glycoprotein (alpha 1AG) levels in 96 women with normal pregnancies were done by an enzyme-linked immunosorbent assay developed in this laboratory. Plasma alpha 1AG levels in pregnant women of all trimesters and 4-10 weeks post-partum period do not differ significantly from those obtained from healthy women of child bearing age. In nine women whose pregnancies were complicated by acute inflammation, plasma levels of alpha 1AG were significantly higher. These findings suggest that in normal pregnancy, alpha 1 AG levels in the plasma remain unchanged. But, pregnancy does not obscure alpha 1 AG response to acute inflammation.