ABSTRACT
Complex regulatory mechanisms control the expression of folate transporters within cells. Liver is the primary reserve of the folate stores within the body. As excessive alcohol consumption or inefficient dietary folate intake are known to create folate deficiency, so therefore the current study was designed to explore various regulatory mechanisms controlling the expression of folate transport in liver cells in conditions of ethanol exposure and folate deficiency. In order to see whether the effects mediated by the treatments are reversible or not, ethanol removal, and folate repletion was done after ethanol exposure and folate deficiency treatment respectively. Folate deficiency resulted an increase, whereas ethanol treatment decreased the folic acid uptake within the cells. The alterations in folic acid uptake were in agreement with the observed changes in the expression of folate transporters. Ethanol exposure resulted an increase in promoter methylation of reduced folate carrier; however, folate deficiency had no effect. The effects produced by ethanol exposure and folate deficiency were found to be reversible in nature as depicted in case of ethanol removal and folate repletion group. Rate of synthesis of folate transporters was found to be increased whereas half lives of mRNA of folate transporters was found to be decreased on folate deficiency treatment and reverse was the case on ethanol treatment. Overall, alteration in the expression of folate transporters under ethanol exposure and folate deficient conditions can be attributed to those regulatory mechanisms which work at the mRNA level.
Subject(s)
Ethanol/pharmacology , Folic Acid/pharmacology , Gene Expression Regulation/drug effects , Proton-Coupled Folate Transporter/genetics , RNA, Messenger/metabolism , Reduced Folate Carrier Protein/genetics , Biological Assay , Biological Transport , Cell Survival/drug effects , DNA Methylation/drug effects , Folate Receptor 1/agonists , Folate Receptor 1/antagonists & inhibitors , Folate Receptor 1/genetics , Folate Receptor 1/metabolism , Folic Acid Deficiency/genetics , Folic Acid Deficiency/metabolism , Folic Acid Deficiency/pathology , Hep G2 Cells , Humans , Lacticaseibacillus casei/growth & development , Lacticaseibacillus casei/metabolism , Models, Biological , Promoter Regions, Genetic , Proton-Coupled Folate Transporter/agonists , Proton-Coupled Folate Transporter/antagonists & inhibitors , Proton-Coupled Folate Transporter/metabolism , RNA, Messenger/agonists , RNA, Messenger/antagonists & inhibitors , RNA, Messenger/genetics , Reduced Folate Carrier Protein/agonists , Reduced Folate Carrier Protein/antagonists & inhibitors , Reduced Folate Carrier Protein/metabolism , Signal Transduction , TritiumABSTRACT
Bmi1 gene overexpression is found in various human tumors and has been shown as a potential target for gene treatment. However, siRNA-based treatments targeting Bmi1 gene have been restricted to limited delivery, low bioavailability and hence relatively reduced efficacy. To overcome these barriers, we developed a folate receptor targeted co-delivery system folate-doxorubicin/Bmi1 siRNA liposome (FA-DOX/siRNA-L). The FA-DOX/siRNA-L was prepared through electrostatic interaction between folate doxorubicin liposome (FA-DOX-L) and Bmi1 siRNA. In vitro and in vivo studies showed that FA-DOX/siRNA-L inhibited tumor growth by combinatory role of Bmi1 siRNA and doxorubicin (DOX). Co-delivery of Bmi1 siRNA and DOX by FA-DOX/siRNA-L showed significantly higher efficacy than sole delivery of either DOX or Bmi1 siRNA. Real-time PCR and western blot analysis showed that FA-DOX/siRNA-L silenced the expression of Bmi1 gene. In addition, higher accumulation of the siRNA and DOX in tumor cells indicated that folate ligand displayed tumor targeting effect. These results suggest that Bmi1 is an effective therapeutic target for siRNA based cancer treatment that can be further improved by co-delivery of DOX through targeted liposomes.
Subject(s)
Doxorubicin/pharmacokinetics , Folate Receptor 1/agonists , Folic Acid/metabolism , Liposomes/metabolism , Polycomb Repressive Complex 1/antagonists & inhibitors , RNA, Small Interfering/pharmacokinetics , Animals , Blotting, Western , Cell Line, Tumor , Drug Carriers/administration & dosage , Female , Gene Expression Profiling , Humans , Mice, Inbred BALB C , Real-Time Polymerase Chain ReactionABSTRACT
The folate receptor (FR) is expressed in many tumor types, among those ovarian and lung cancer. Due to the high FR affinity of folic acid, it has been used for targeting of FR-positive tumors, allowing specific delivery of attached probes to the malignant tissue. Therefore, nuclear imaging of FR-positive cancer is of clinical interest for selecting patients who could benefit from innovative therapy concepts based on FR-targeting. Positron emission computed tomography (PET) has become an established technique in clinical routine because it provides an increased spatial resolution and higher sensitivity compared to single photon emission computed tomography (SPECT). Therefore, it is of critical importance to develop folate radiotracers suitable for PET imaging. This review article updates on the design, preparation and pre-clinical investigation of folate derivatives for radiolabeling with radioisotopes for PET. Among those the most relevant radionuclides so far are fluorine-18 (t(1/2): 110 min, E(av) ყ: 250 keV) and gallium-68 (t(1/2): 68 min, E(av) ყ: 830 keV). Recent results obtained with new PET isotopes such as terbium-152 (t(1/2): 17.5 h, Eყ: 470 keV) or scandium-44 (t(1/2): 3.97 h, (Eav) ყ: 632 keV) are also presented and discussed. Current endeavors for clinical implementation of PET agents open new perspectives for identification of FR-positive malignancies in patients.
