Autocrine growth loops dependent on peptidyl α-amidating enzyme as targets for novel tumor cell growth inhibitors

Iwai, Naomichi; Martı́nez, Alfredo; Miller, Matthew T.; Vos, Michele D.; Mulshine, James L.; Treston, Anthony M.

doi:10.1016/s0169-5002(99)00015-x

Cited by 29 publications

(18 citation statements)

References 27 publications

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“…The increase in PAM biosynthesis is associated with the production of ␣-amidated peptides, 45 some of which could act as autocrine/paracrine factors and influence the response of neighboring neoplastic cells. A previous study on small cell lung cancer 46 has shown that bombesin/GRP, an ␣-amidated peptide, acts as an autocrine growth factor in these cells 47 which further supports a key role of PAM in tumor growth. A preliminary survey of amidated peptides present in glioblastoma-derived cell lines (U373, U138, U87, SW1783, and SW1088) demonstrated that AM is predominately represented both as mRNA and immunoreactive peptide in these cell lines.…”

Section: Discussionsupporting

confidence: 58%

Neutralization of Adrenomedullin Inhibits the Growth of Human Glioblastoma Cell Lines in Vitro and Suppresses Tumor Xenograft Growth in Vivo

Ouafik¹,

Sauze²,

Boudouresque³

et al. 2002

The American Journal of Pathology

119

159

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Presently, there is no effective treatment for glioblastoma, the most malignant and common brain tumor. Growth factors are potential targets for therapeutic strategies because they are essential for tumor growth and progression. Peptidylglycine ␣-amidating monooxygenase is the enzyme producing ␣-amidated bioactive peptides from their inactive glycine-extended precursors. The high expression of peptidylglycine ␣-amidating monooxygenase mRNA in glioblastoma and glioma cell lines points to the involvement of ␣-amidated peptides in tumorigenic growth processes in the brain. After screening of amidated peptides, it was found that human glioblastoma cell lines express high levels of adrenomedullin (AM) mRNA, and that immunoreactive AM is released into the culture medium. AM is a multifunctional regulatory peptide with mitogenic and angiogenic capabilities among others. Real-time quantitative reverse transcriptase-polymerase chain reaction analysis showed that AM mRNA was correlated to the tumor type and grade, with high expression in all glioblastomas analyzed, whereas a low expression was found in anaplastic astrocytomas and barely detectable levels in low-grade astrocytomas and oligodendrogliomas. In the present study we also demonstrate the presence of mRNA encoding the putative AM receptors, calcitonin receptor-like receptor/receptor activity-modifying protein-2 and -3 (CRLR/RAMP2; CRLR/RAMP3) in both glioma tissues and glioblastoma cell lines and further show that exogenously added AM can stimulate the growth of these glioblastoma cells in vitro. These findings suggest that AM may function as an autocrine growth factor for glioblastoma cells. One way to test the autocrine hypothesis is to interrupt the function of the endogenously produced AM. Herein, we demonstrate that a polyclonal antibody specific to AM, blocks the binding of the hormone to its cellular receptors and decreases by 33% (P < 0.001) the growth of U87 glioblastoma cells in vitro. Malignant glioblastomas are highly aggressive tumors with a median patient survival time of 9 to 14 months.

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Section: Discussionsupporting

confidence: 58%

Neutralization of Adrenomedullin Inhibits the Growth of Human Glioblastoma Cell Lines in Vitro and Suppresses Tumor Xenograft Growth in Vivo

Ouafik¹,

Sauze²,

Boudouresque³

et al. 2002

The American Journal of Pathology

119

159

View full text Add to dashboard Cite

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“…Thus, raising or lowering the level of PAM protein by transfection with sense or antisense PAM vectors results in a corresponding increase or decrease in peptide h-amidation [12]. The growth of lung tumor cell lines is slowed upon antisense-mediated decreases in PAM expression [68]. Consistent with a rate-limiting role for amidation, levels of PAM synthesis in melanotropes are 10,000-fold lower that levels of substrate (proopiomelanocortin) synthesis, and it is estimated that each secretory granule contains an average of one molecule of PAM [69].…”

Section: Review Articlementioning

confidence: 99%

New insights into copper monooxygenases and peptide amidation: structure, mechanism and function

Prigge

Mains

Eipper

et al. 2000

CMLS, Cell. Mol. Life Sci.

437

458

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Many bioactive peptides must be amidated at their carboxy terminus to exhibit full activity. Surprisingly, the amides are not generated by a transamidation reaction. Instead, the hormones are synthesized from glycine-extended intermediates that are transformed into active amidated hormones by oxidative cleavage of the glycine N-C alpha bond. In higher organisms, this reaction is catalyzed by a single bifunctional enzyme, peptidylglycine alpha-amidating monooxygenase (PAM). The PAM gene encodes one polypeptide with two enzymes that catalyze the two sequential reactions required for amidation. Peptidylglycine alpha-hydroxylating monooxygenase (PHM; EC 1.14.17.3) catalyzes the stereospecific hydroxylation of the glycine alpha-carbon of all the peptidylglycine substrates. The second enzyme, peptidyl-alpha-hydroxyglycine alpha-amidating lyase (PAL; EC 4.3.2.5), generates alpha-amidated peptide product and glyoxylate. PHM contains two redox-active copper atoms that, after reduction by ascorbate, catalyze the reduction of molecular oxygen for the hydroxylation of glycine-extended substrates. The structure of the catalytic core of rat PHM at atomic resolution provides a framework for understanding the broad substrate specificity of PHM, identifying residues critical for PHM activity, and proposing mechanisms for the chemical and electron-transfer steps in catalysis. Since PHM is homologous in sequence and mechanism to dopamine beta-monooxygenase (DBM; EC 1.14.17.1), the enzyme that converts dopamine to norepinephrine during catecholamine biosynthesis, these structural and mechanistic insights are extended to DBM.

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“…PBA decreased lung cancer cell proliferation, presumably by inhibiting the synthesis of amidated growth factors [Iwai et al, 1999]. We previously demonstrated that PBA inhibited the growth of ras -transformed WB-F344 cells and up-regulated gap junction-mediated cell-cell communication and connexin 43 [Sunman et al, 2004].…”

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confidence: 99%

p38 MAPK activation, JNK inhibition, neoplastic growth inhibition, and increased gap junction communication in human lung carcinoma and Ras‐transformed cells by 4‐Phenyl‐3‐butenoic acid

Matesic

Sidorova

Burns

et al. 2011

J of Cellular Biochemistry

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Human lung neoplasms frequently express mutations that down-regulate expression of various tumor suppressor molecules, including mitogen-activated protein kinases such as p38 MAPK. Conversely, activation of p38 MAPK in tumor cells results in cancer cell cycle inhibition or apoptosis initiated by chemotherapeutic agents such as retinoids or cisplatin, and is therefore an attractive approach for experimental anti-tumor therapies. We now report that 4-phenyl-3-butenoic acid (PBA), an experimental compound that reverses the transformed phenotype at non-cytotoxic concentrations, activates p38 MAPK in tumorigenic cells at concentrations and treatment times that correlate with decreased cell growth and increased cell-cell communication. H2009 human lung carcinoma cells and ras-transformed liver epithelial cells treated with PBA showed increased activation of p38 MAPK and its downstream effectors which occurred after 4 h and lasted beyond 48 h. Untransformed plasmid control cells showed low activation of p38 MAPK compared to ras-transformed and H2009 carcinoma cells, which correlates with the reduced effect of PBA on untransformed cell growth. The p38 MAPK inhibitor, SB203580, negated PBA’s activation of p38 MAPK downstream effectors. PBA also increased cell-cell communication and connexin 43 phosphorylation in ras-transformed cells, which were prevented by SB203580. In addition, PBA decreased activation of JNK, which is upregulated in many cancers. Taken together, these results suggest that PBA exerts its growth regulatory effect in tumorigenic cells by concomitant up-regulation of p38 MAPK activity, altered connexin 43 expression, and down-regulation of JNK activity. PBA may therefore be an effective therapeutic agent in human cancers that exhibit down-regulated p38 MAPK activity and/or activated JNK and altered cell-cell communication.

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Autocrine growth loops dependent on peptidyl α-amidating enzyme as targets for novel tumor cell growth inhibitors

Cited by 29 publications

References 27 publications

Neutralization of Adrenomedullin Inhibits the Growth of Human Glioblastoma Cell Lines in Vitro and Suppresses Tumor Xenograft Growth in Vivo

Neutralization of Adrenomedullin Inhibits the Growth of Human Glioblastoma Cell Lines in Vitro and Suppresses Tumor Xenograft Growth in Vivo

New insights into copper monooxygenases and peptide amidation: structure, mechanism and function

p38 MAPK activation, JNK inhibition, neoplastic growth inhibition, and increased gap junction communication in human lung carcinoma and Ras‐transformed cells by 4‐Phenyl‐3‐butenoic acid

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