title: Gamma-aminobutyric acid as a promoting factor of cancer metastasis; induction of matrix metalloproteinase production is potentially its underlying mechanism.
abstract: We investigated expression of gamma-aminobutyric acid (GABA), glutamate decarboxylase, and matrix metalloproteinase (MMP) in the prostates of patients with cancer or benign prostatic hypertrophy by immunohistochemical study. Marked expression of GABA, glutamate decarboxylase 67, and MMPs was observed in the prostates of cancer patients with metastasis (n = 72) and lymph node metastasis, although only sparse expression was noted in those of cancer patients without metastasis (n = 76) or patients with benign prostatic hypertrophy (n = 152). We then investigated the influence of GABA stimulation on in vitro MMP production and the invasive ability of cancer cells using human prostate cancer cell line C4-2. The production of MMPs increased significantly in cancer cells after a 24-h incubation with GABA. Cell invasion assay using a BioCoat Matrigel Invasion Chamber kit revealed that GABA stimulation significantly promoted the invasive ability of cancer cells and that addition of MMP inhibitor GM6001 significantly decreased GABA-induced migration. This may indicate the involvement of MMP activity in GABA-induced cancer cell invasion. We further analyzed the transmission pathway by performing GABA receptor modulation. The GABA(B) receptor agonist baclofen significantly increased MMP production as well as invasive ability. Moreover, blockade of the GABA(B) receptor pathway using GABA(B) receptor antagonist CGP 35348 significantly inhibited GABA-induced MMP production and invasive ability in cancer cells, whereas GABA(A) receptor modulation did not influence MMP production or the invasive ability of cancer cells. Thus, increased expression of GABA may be implicated in cancer metastasis by promoting MMP production in cancer cells, and the GABA(B) receptor pathway may be involved in the process.
authors.affiliation: Departments of Urology, Osaka Medical College, Takatsuki, Osaka, Japan.
authors.forename: Haruhito
authors.initials: H
authors.lastname: Azuma
authors.forename: Teruo
authors.initials: T
authors.lastname: Inamoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kiyama
authors.forename: Takanobu
authors.initials: T
authors.lastname: Ubai
authors.forename: Yuko
authors.initials: Y
authors.lastname: Shinohara
authors.forename: Kentaro
authors.initials: K
authors.lastname: Maemura
authors.forename: Motomu
authors.initials: M
authors.lastname: Tsuji
authors.forename: Naoki
authors.initials: N
authors.lastname: Segawa
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Masuda
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Takahara
authors.forename: Yoji
authors.initials: Y
authors.lastname: Katsuoka
authors.forename: Masahito
authors.initials: M
authors.lastname: Watanabe
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001418:Baclofen / Q000494:pharmacology; D004151:Dipeptides / Q000494:pharmacology; D004790:Enzyme Induction; D018755:GABA Agonists / Q000494:pharmacology; D058786:GABA-B Receptor Agonists; D005968:Glutamate Decarboxylase / Q000096:biosynthesis; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000096:biosynthesis; D008207:Lymphatic Metastasis; D008297:Male; D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases / Q000096:biosynthesis*; D008875:Middle Aged; D009362:Neoplasm Metastasis; D011470:Prostatic Hyperplasia / Q000201:enzymology / Q000473:pathology; D011471:Prostatic Neoplasms / Q000201:enzymology* / Q000473:pathology*; D011480:Protease Inhibitors / Q000494:pharmacology; D018080:Receptors, GABA-B / Q000502:physiology; D012307:Risk Factors; D005680:gamma-Aminobutyric Acid / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology*
chemical_list: D004151:Dipeptides; D018755:GABA Agonists; D058786:GABA-B Receptor Agonists; D007527:Isoenzymes; D061965:Matrix Metalloproteinase Inhibitors; C078131:N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide; D011480:Protease Inhibitors; D018080:Receptors, GABA-B; D005680:gamma-Aminobutyric Acid; D020782:Matrix Metalloproteinases; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1; D001418:Baclofen