ABSTRACT
Tumor cells are generally poorly responsive to immunotherapy. The results presented here suggest that antigen presentation of somatic tumor cells may be diminished greatly in quiescence and may be determined in part by growth regulation. Peptides produced by proteasomes are transported into the endoplasmic reticulum by transporter proteins TAP-1 and TAP-2, where they bind and stabilize MHC class I molecules required for antigenic presentation on the cell surface. TAP-1 and TAP-2 mRNAs were undetectable in quiescent, serum-deprived human breast cancer cells (21PT). They appeared 10 h after serum induction, near the G(1)-S boundary. In contrast, HLA-B27 mRNA was biphasically up-regulated. These mRNAs were significantly down-regulated in most tissues that contain mainly terminally differentiated, nonproliferating cells. All of the investigated breast cancer cell lines showed lower expression levels of these mRNAs than did the corresponding normal cells.
Subject(s)
ATP-Binding Cassette Transporters/genetics , Antigen Presentation , Antigens, Neoplasm/genetics , Breast Neoplasms/metabolism , Cell Cycle/genetics , Gene Expression Regulation, Neoplastic , HLA-B27 Antigen/genetics , Neoplasm Proteins/genetics , RNA, Messenger/biosynthesis , RNA, Neoplasm/biosynthesis , ATP Binding Cassette Transporter, Subfamily B, Member 2 , ATP Binding Cassette Transporter, Subfamily B, Member 3 , ATP-Binding Cassette Transporters/biosynthesis , Antigens, Neoplasm/biosynthesis , Breast/cytology , Breast/metabolism , Breast Neoplasms/genetics , Breast Neoplasms/immunology , Breast Neoplasms/pathology , Cell Division , Cells, Cultured , Culture Media, Serum-Free , Epithelial Cells , Epithelium/metabolism , Female , HLA-B27 Antigen/biosynthesis , Humans , Neoplasm Proteins/biosynthesis , RNA, Messenger/genetics , RNA, Neoplasm/genetics , Tumor Cells, CulturedABSTRACT
BACKGROUND: The decision for a cell to enter the DNA synthesis (S) phase of the cell cycle or to arrest in quiescence is likely to be determined by genes expressed in the late G1 phase, at the restriction point. Loss of restriction point control is associated with malignant cellular transformation and cancer. For this reason, identifying genes that are differentially expressed in late G1 phase versus quiescence is important for understanding the molecular basis of normal and malignant growth. MATERIALS AND METHODS: The differential display (DD) method detects mRNA species that are different between sets of mammalian cells, allowing their recovery and cloning of the corresponding cDNAs. Using this technique, we compared mRNAs from synchronized human breast cancer cells (21 PT) in quiescence and in late G1. RESULTS: Six mRNAs differentially expressed in late G1 or in quiescence were identified. One mRNA expressed 10 hr after serum induction showed 99% homology to a peptide transporter involved in antigen presentation of the class I major histocompatibility complex (TAP-1) mRNA. Another mRNA expressed specifically in quiescence and down-regulated 2 hr following serum induction showed 98% homology to human NADP+ -dependent cytoplasmic malic enzyme (EC1.1.1.40) mRNA, which is an important enzyme in fatty acid synthesis and lipogenesis. Three others showed high homology to different mRNAs in the GeneBank, corresponding to genes having unknown functions. Finally, one mRNA revealed no significant homology to known genes in the GeneBank. CONCLUSIONS: We conclude that DD is an efficient and powerful method for the identification of growth-related genes which may have a role in cancer development.
Subject(s)
Breast Neoplasms/genetics , G1 Phase , RNA, Messenger/chemistry , Base Sequence , Blotting, Northern , Breast Neoplasms/pathology , DNA, Complementary/chemistry , Female , Humans , Molecular Sequence Data , Resting Phase, Cell Cycle , Tumor Cells, CulturedABSTRACT
Tumor suppressor p53 is a nuclear protein that is induced by DNA damage and is involved in G1 and G2 phase control of the cell cycle. p21WAF1/CIP1/SDI1 (p21), a cyclin-dependent kinase inhibitor, is a downstream target and effector of p53 to induce G1 arrest. Mimosine is a potent reversible late G1 phase blocker of the cell cycle. In this study, we showed that mimosine can increase both p21 mRNA and protein levels, indirectly inhibit cyclin E-associated kinase activity without affecting the cyclin E protein level, block human breast cancer cells (21PT) in the late G1 phase of the cell cycle, and induce a p53-independent p21 pathway in these cells. These results support the possibility of restoring a G1 checkpoint by use of mimosine. They also suggest that the mechanism of the effect of mimosine is complex and may have more than one target in the cell.
Subject(s)
Cell Cycle/drug effects , Cyclins/metabolism , Mimosine/pharmacology , Signal Transduction/drug effects , Tumor Suppressor Protein p53/metabolism , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Cyclin-Dependent Kinase Inhibitor p21 , Female , Humans , RNA, Messenger/biosynthesis , Tumor Cells, CulturedABSTRACT
Nineteen 10-[2-(N,N-disubstituted thiocarbamoylthio) acetyl]phenothiazine derivatives have been synthesized by the reaction of 10-chloroacetylphenothiazine with potassium salt of N,N-disubstituted dithiocarbamic acid derivatives. The structures of the compounds have been elucidated by UV, IR, 1H-NMR spectra and microanalysis. The anticholinergic activity of the compounds was determined by assessing the inhibition of acetylcholine using atropine sulfate as a control. Results are discussed in relation to the activity and structure of the synthesized compounds.
Subject(s)
Parasympatholytics/chemical synthesis , Phenothiazines/chemical synthesis , Thiocarbamates/chemical synthesis , Acetylcholine/pharmacology , Animals , Atropine/pharmacology , Female , In Vitro Techniques , Isometric Contraction/drug effects , Magnetic Resonance Spectroscopy , Male , Muscle Contraction/drug effects , Muscle, Smooth, Vascular/drug effects , Parasympatholytics/pharmacology , Phenothiazines/pharmacology , Rats , Spectrophotometry, Ultraviolet , Structure-Activity Relationship , Thiocarbamates/pharmacologyABSTRACT
The effect of vasoactive intestinal polypeptide (VIP) on the contractile activity of the urinary bladder was investigated in the rat. VIP caused a weak contraction and a small potentiation of carbachol- and acetylcholine-induced contractions. The present results may provide the evidence that VIP could be a modulator in the urinary bladder.
Subject(s)
Muscle Contraction/drug effects , Muscle, Smooth/physiology , Urinary Bladder/physiology , Vasoactive Intestinal Peptide/pharmacology , Acetylcholine/pharmacology , Animals , Carbachol/pharmacology , In Vitro Techniques , Male , Muscle, Smooth/drug effects , Rats , Urinary Bladder/drug effects , Vasoactive Intestinal Peptide/physiologyABSTRACT
The effects of a 7 days chemotherapy with ciprofloxacin or ofloxacin on the cellular and humoral immune responses in albino mice were studied. The non-toxic doses of the drugs (10 or 30 mg/kg/day) were used. The delayed-type hypersensitivity reaction to sheep blood cells and skin biopsy were evaluated for cellular immune response. The complement fixation method was applied for the determination of the humoral immune response. Both drugs increased the cellular and humoral immune responses.
