Intraperitoneal administration of poly(I:C) with polyethylenimine leads to significant antitumor immunity against murine ovarian tumors

Ovarian cancer is currently the most lethal gynecologic cancer in the United States. There is an urgent need for the development of innovative therapies against ovarian cancer, such as immunotherapy. The toll-like receptor 3 ligand, polyriboinosinic:polyribocytidylic acid (poly(I:C), has emerged as a promising adjuvant for activating the host immune responses for the control of tumors. We reasoned that a strategy to enhance the intracellular uptake of poly(I:C) will likely improve the poly(I:C) adjuvant effect. Since polyethylenimine (PEI) has been shown to increase the transfection efficiency of nucleic acids, we characterized the antitumor effects in mouse ovarian surface epithelial cells (MOSEC) tumor-bearing mice treated intraperitoneally with poly(I:C) and PEI. We observed that tumor-bearing mice treated with poly(I:C) and PEI generated significantly better therapeutic antitumor effects against MOSEC tumors compared with treatment with poly(I:C) alone. Furthermore, we found that NK cells play a significant role in the antitumor effects generated by treatment with poly(I:C) in combination with PEI. Intraperitoneal administration of poly(I:C) with PEI led to the uptake of poly(I:C) mainly by CD11b+ macrophages, resulting in the high expression of MHC class II and IL-12 (M1 phenotype). In addition, adoptive transfer of CD11b+ macrophages from mice treated with poly(I:C) and PEI was found to lead to increased number of activated NK cells in the recipient mice. Taken together, our data indicate that PEI can potentially be used to improve the uptake of poly(I:C) by CD11b+ macrophages, leading to the activation of NK cells and the control of murine ovarian tumors.     

Poly(A): A new evolutionary probe

The poly(A) segment increases in length as the complexity of the organism increases. The shortest poly(A) size (10–15 AMP units) exist on mRNA from bacteria. The largest poly(A) segments (180–200 AMP units) exist in highly differentiated tissue. The natural log of average poly(A) size has evolved in a linear manner with the time of evolution of different organisms. This relationship places the origin of mRNA, and possibly life, at 3·85 ± 0.2 billion years ago. The poly(A) length of mitochondrial mRNA places the origin of mitochondria within eucaryotes at 2· 1 billion years ago.     

The kinetics of pancreatic ribonuclease reaction with alkaline and acidic forms of poly A

Summary The RNase hydrolysis of random-coil (alkaline form) poly A follows biphasic kinetics at low salt concentrations. However, its resistance to RNase increases with the ionic strength. Helical (acidic form) poly A is also susceptible to RNase but its hydrolysis follows first-order kinetics, and its resistance increases as the pH is lowered. These conformation-dependent kinetics of poly A hydrolysis are similar to those obtained in the hydrolysis of cellular RNA and reovirus double-stranded RNA.     

Detection, sizing, and quantitation of polyadenylated ribonucleic acid in the nanogram-picogram range

A method is described for using very high specific activity [3H]poly(deoxythymidylate) [[3H]poly(dT)] to detect, size, and quantiate subnanogram amounts of nonradioactive polyadenylated RNA. Short (approximately 100 nucleotides long) [3H]poly(dT) is hybridized to the poly(adenylate) [poly(A)] tracts in polyadenylated RNAs. The RNA may then be sized and quantitated by sucrose gradient analysis. The addition of the small [3H]poly(dT) molecules does not significantly alter the s values of RNAs. The amount of [3H]poly(dT) hybridized to polyadenylated RNA increases linearly with the amount of RNA. A room temperature hydroxylapatite (HA) method has also been developed to detect and quantitate poly(A)-containing RNA after hybridization to radioactive poly(dT). S-1 nuclease (S-1) analysis can also be used to measure the poly(A) content of polyadenylated RNA to less than nanogram RNA amounts. For both the S-1 and HA approaches, the amount of [3H]poly(dT) hybridized increases with the amount of RNA and the methods can detect to as little as 10(-12) g of polyadenylated RNA with [3H]poly(dT). Greater sensitivity is possible with higher specific activity poly(dT). The approaches presented here significantly extend the uses of radioactive homopolymers to detect, quantitate, and characterize RNAs containing complementary homopolymer tracts.     

Interaction of phospholipid membranes with poly(ethylene glycol)s

1. The water-soluble polymer, poly(ethylene glycol), causes concentration-dependent increases in the temperature of the gel--liquid crystalline phase transitions of aqueous dispersions of dipalmitoyl phosphatidylcholine and of dipalmitoyl phosphatidylethanolamine. 2. For dipalmitoyl phosphatidylcholine it has been further demonstrated that poly(ethylene glycol) increases the transition enthalpy and entropy while decreasing the cooperativity of the transition. 3. These results are discussed in relation to the possible modes of action of poly(ethylene glycol) in promoting cell fusion.     

Single strand conformation of adenylate chains analysed by a specific photoreaction. Determination of structure by 5'' residue.

The photoreactivity was analysed in various oligo- and polyadenylates: 1) The quantum yields of the specific photoreaction in poly(dA) and dApdA decrease with increasing temperature, whereas the quantum yield of the photodegradation in poly(rA) increases. 2) The photoreactivities of poly(2'MeA) and poly(2'EtA) closely correspond to that of poly(rA). 3) The photodegradation of rApdA is very similar to that of rAprA, whereas dAprA shows the same specific photoreaction as observed for dApdA. These data support the view, that the specific photoreaction observed in oligo(dA) and poly(dA) is dependent upon a specific conformation, which is not accessible to oligo(rA), poly(rA), poly(2'MeA) and poly(2'EtA). The specific conformation is determined by the nucleotide, which carries the internucleotide bond in the 3'-position.     

Changes in hepatic RNA, poly(A)+RNA, and poly(A)-RNA during the acute phase response to inflammation

The steady state changes in total rat hepatic cytoplasmic RNA, poly(A)+ RNA and poly(A)-RNA were assessed in response to turpentine induced inflammation. From 18 to 24 h after injury, cytoplasmic RNA doubled, while poly(A)+ RNA peaked at 24 h, 3.5 times over control animals. Cell-free translation showed significant increases in messenger RNA levels beginning at 18 h. Gel electrophoresis of translation products revealed significant increases in several polypeptides and a decrease in others. Poly(A)-RNA from control and injured rats translated to an insignificant level and the electrophoretic gel patterns of their proteins were similar. Furthermore, no change had occurred in the 3' poly(A)-sequences during the course of inflammation.     

Interferon and Interferon Inducers in the Treatment of Malignancies

The mechanism of the antitumor action of polyinosinic-polycytidylic acid is probably multifaceted. The compound induces the synthesis of interferon, and interferon probably is active against some tumors. Poly I:poly C alters protein and RNA synthesis in tissue culture. It specifically inhibits such macromolecule synthesis in tumors in vivo, while having less inhibitory action on synthesis in normal organs, or it may actually enhance. Finally, poly I:poly C strongly enhances graft vs. host rejection mechanisms, which may play a role in the rejection of some tumors.     

Polyadenylation of 35S RNA in vitro by a cytoplasmic particulate fraction from mouse myeloma.

An ATP incorporating activity was found to be associated with cytoplasmic particulate fractions prepared from MOPC-104E tumors (a mouse plasmacytoma). The product was shown to be poly(A) by its chromatography pattern on oligo(dT) cellulose columns, and the endogenous primers included a 35S RNA species as analysed by Cs₂SO₄ density centrifugation and polyacrylamide gel electrophoresis. The labeled poly(A) was estimated to have a chain length of 200 nucleotides by gel electrophoresis, and hydrolysis of the poly(A) yielded approximately 100 AMP residues for every adenosine residue.     

Thermogelling aqueous solutions of alternating multiblock copolymers of poly(L-lactic acid) and poly(ethylene glycol)

We are reporting alternating multiblock copolymers of poly(L-lactic acid)/poly(ethylene glycol) aqueous solution (> 15 wt %) undergoing sol-gel-sol transition as the temperature increases from 20 to 60 degrees C. Micelles of the multiblock copolymers (in water) are about 20 nm in radius at low temperature. They are aggregated to a larger size as the temperature increases, which should play a critical role in the sol-to-gel transition. The transition temperature and gel window were affected by the molecular weight and composition of the multiblock copolymer. In particular, the aqueous solution of an alternating multiblock copolymer (Mn approximately 6700 daltons) prepared from poly(ethylene glycol) (Mn approximately 600 daltons) and poly(L-lactic acid) (Mn approximately 1300 daltons) showed a maximum modulus at body temperature (37 degrees C). The in situ gel forming ability of the polymer aqueous solution in vivo as well as in vitro indicates that it can be a promising injectable biomaterial.     

Developmental changes in poly(A) polymerase activity in Artemia

The levels of poly(A) polymerase activity have been determined during Artemia early development. Poly(A) polymerase activity increases steadily during postgastrular embryonic development reaching a maximum shortly after hatching. The rise of poly(A) polymerase is concomitant with an increase in poly(A) content and with a change in the subcellular distribution of the enzyme activity, the major increase corresponding to the nuclear fraction. Only one isoenzyme of poly(A) polymerase has been identified in Artemia embryos and nauplii despite changes in enzyme levels and subcellular changes during early development. Poly(A) polymerase is not associated with the cytoplasmic poly(A)-containing ribonucleoprotein particles stored in Artemia dormant embryos.     

In vitro translation of mRNA from rat pheochromocytoma tumors, characterization of tyrosine hydroxylase

Studies are presented which demonstrate that rat pheochromocytoma tumors are a convenient material for the preparation of tyrosine hydroxylase mRNA. Total pheochromocytoma poly(A)⁺mRNA has been extracted from tumors, then translated in a reticulocyte lysate cell-free system. Neo-synthesized tyrosine hydroxylase has been identified by direct immunoprecipitation followed by sodium dodecyl sulfate acrylamide gel electrophoresis. The proportion of this specific mRNA has been calculated; it represents 0.15 per cent of the total poly(A)⁺mRNA. The molecular weight of the $\text{in}\text{vitro}$ synthesized tyrosine hydroxylase is 62,000.     

A spin label study of purple membranes from Halobacterium halobium.

Mammary tumors induced in Sprague-Dawley Rats by the carcinogen 7,12-dimethylbenz(a)anthracene contain a DNA polymerase similar to that found in RNA tumor viruses. It has a molecular weight of 105,000 daltons and is active on the synthetic templates poly(rA):oligo(dT) and poly(rC):-oligo(dG) but is inactive on poly(dA):oligo(dT). This polymerase may be purified more than 300 fold with a 25% yield by ammonium sulfate precipitation, phosphocellulose chromatography and hydroxyapatite chromatography. A similar polymerase is also found in lactating normal rat mammary tissues.     

Effect of non-complementary nucleotides on the rate of helix formation: kinetics of formation of poly (I)-poly (C,I) and poly (I)-poly (C,U) complexes

Apparent second-order rate constants for complex formation between poly (I) and poly (C) and copolymers of C containing non-complementary I or U residues have been determined spectrophotometrically. The rate constants decrease as the concentration of either I or U in the C strands increases–the effect seems insensitive to the species of residue involved, when differences in the thermal stabilities of the poly (I) poly (C,I) and poly (I). poly (C,U) complexes are taken into account. These results suggest that low concentrations of relatively stable defects can alter the apparent kinetic “complexity” of polynucleotides as determined by hybridization methods (C₀t analysis).