ABSTRACT
Actinobacillus actinomycetemcomitans strain 310-TR produces fimbriae and forms a tight biofilm in broth cultures, without turbid growth. The fimbriae-deficient mutant 310-DF, constructed in this study, was grown as a relatively fragile biofilm at the bottom of a culture vessel. Scanning electron microscopy revealed that on glass coverslips, 310-TR formed tight and spherical microcolonies, while 310-DF produced looser ones. These findings suggest that fimbriae are not essential for the surface-adherent growth but are required for enhancing cell-to-surface and cell-to-cell interactions to stabilize the biofilm. Treatment of the 310-DF biofilm with either sodium metaperiodate or DNase resulted in significant desorption of cells from glass surfaces, indicating that both carbohydrate residues and DNA molecules present on the cell surface are also involved in the biofilm formation.
Subject(s)
Aggregatibacter actinomycetemcomitans/physiology , Bacterial Adhesion , Biofilms/growth & development , Fimbriae Proteins/metabolism , Aggregatibacter actinomycetemcomitans/genetics , Fimbriae Proteins/deficiency , Fimbriae Proteins/geneticsABSTRACT
Cisplatin (CDDP) is a useful drug for the treatment of malignant solid tumors of the head and neck. Because CDDP includes the heavy metal platinum as a component, it is thought metallothionein (MT) may be involved in CDDP-resistance. However, functional differences between the four MT isoforms (MT-I, II, III and IV) remain unclear. The aim of this study was to investigate the relationship between MT isoform expression and CDDP-resistance. Two human tongue squamous cell carcinoma cell lines not exposed to anticancer chemotherapy were studied. The cell lines were subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) analysis before and after CDDP-treatment. Both cell lines expressed MT-I/II and MT-IV isoforms but not the MT-III isoform. Following CDDP treatment, MT-I/II mRNA levels were induced only in the CDDP-resistant cell line. Our results showed that expression of the MT I/II isoform was induced by CDDP treatment, and may play an important role in CDDP-resistance in squamous cell carcinoma of the human tongue.
Subject(s)
Antineoplastic Agents/pharmacology , Carcinoma, Squamous Cell/drug therapy , Carcinoma, Squamous Cell/metabolism , Cisplatin/pharmacology , Metallothionein/biosynthesis , Tongue Neoplasms/drug therapy , Tongue Neoplasms/metabolism , Carcinoma, Squamous Cell/genetics , Drug Screening Assays, Antitumor , Humans , Metallothionein/genetics , Protein Isoforms/biosynthesis , Protein Isoforms/genetics , RNA, Messenger/biosynthesis , RNA, Messenger/genetics , Reverse Transcriptase Polymerase Chain Reaction , Tongue Neoplasms/genetics , Tumor Cells, CulturedABSTRACT
Metallothionein (MT)-III is a metal binding protein, called growth inhibitory factor, and is mainly expressed in the central nervous system. Since MT-III decreases in the brain of Alzheimer's disease (AD), a growing interest has been focused on its relationship to neurodegenerative diseases. To clarify age-related changes in the MT-III expression and its inducibility against oxidative stress, we analyzed the expression of MT-III and its mRNA in the brain of lipopolysaccharide (LPS)-treated aged rats. In the frontal cortex, basal expression of MT-III mRNA was significantly increased with aging, while it was observed no induction of MT-III mRNA against LPS administration in the aged rat brain. MT-III immunopositive cells were increased in the frontal, parietal and piriform cortices, hypothalamus and amygdaloid nucleus with aging. The LPS treatment induced MT-III expression in the brain of young-adult rats, but not in the aged rat brain. Furthermore, the MT-III induction with LPS treatment was mainly observed in oligodendrocyte and microglia. In the present study, we showed that inducibility of brain MT-III against oxidative stress may be reduced with aging. Since it has been reported that MT-III has neuroprotective roles as an antioxidant, present results suggest that MT-III is closely related to the neurodegeneration in the aged animals.
