Insulin and IGF-1 increase mitogenesis and glucose metabolism in the multiple myeloma cell line, RPMI 8226

G. G. Freund, D. T. Kulas, R. A. Mooney

Research output: Contribution to journalArticlepeer-review

Abstract

Insulin receptors and insulin-like growth factor-1 (IGF-1) receptors are present in circulating human B lymphocytes (B cells) and certain B cell malignancies, but no function has been attributed to either receptor. We report a human myeloma cell line, RPMI 8226, that exhibits insulin and IGF- 1-dependent receptor and substrate tyrosine phosphorylation as well as hormone-responsive cellular metabolism. Competitive hormone-binding analysis revealed that the cell line expressed approximately 4 x 103 high affinity insulin binding sites and 1.1 x 104 high affinity IGF-1 binding sites per cell. The Kd of the insulin-binding sites for insulin was 0.32 nM. The Kd of high affinity IGF-1 binding sites for IGF-1 was 0.89 nM. Insulin receptor autophosphorylation was maximum at 200 nM as was tyrosine phosphorylation of the 180-kDa cytosolic receptor substrate. Insulin-dependent activation of phosphatidylinositol 3-kinase paralleled receptor phosphorylation. In contrast, IGF-1 produced its maximum effects at 200 nM for receptor phosphorylation and 20 nM for substrate phosphorylation and PI 3-kinase activation. In growth synchronized cells, IGF-1 and insulin at 200 nM increased DNA synthesis by 122 ± 18% and 101 ± 27%, respectively. IGF-1 increased DNA synthesis 88 ± 21% at 2 nM and the effect of insulin at 2 nM was 34 ± 12%. Flux through the glycolytic pathway was also increased by insulin and IGF-1. At 200 and 2 nM, insulin increased production of lactate by 33 ± 9% and 19 ± 11%, respectively. IGF-1 increased lactate production 47 ± 3% and 23 ± 3% at identical hormone concentrations. Finally, in two additional myeloma cell lines, U266 (human) and Ag8.653 (mouse), insulin and IGF-1 increased tyrosine phosphorylation of receptor β-subunit (95 kDa), the prominent 180-kDa substrate (pp185), and several other substrates. Thus, functional insulin and IGF-1 receptors are present in myeloma cell lines. Through these receptors, insulin and IGF-1 regulate mitogenesis and glucose metabolism, and may be important in potentiating plasma cell malignancy.

Original languageEnglish (US)
Pages (from-to)1811-1820
Number of pages10
JournalJournal of Immunology
Volume151
Issue number4
StatePublished - 1993

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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