Cooperative Regulation of the Invasive and Metastatic Phenotypes by Different Domains of the Type I Insulin-like Growth Factor Receptor β Subunit

Abstract

The receptor for the type 1 insulin-like growth factor (IGF-I) regulates multiple cellular functions impacting on the metastatic phenotype of tumor cells, including cellular proliferation, anchorage-independent growth, survival, migration, synthesis of the 72-kDa type IV collagenase and invasion. We have used site-directed mutagenesis to generate domain-specific mutants of the receptor ␤ subunit to analyze the role of specific tyrosines in the regulation of the invasive/metastatic phenotype. Poorly invasive M-27 carcinoma cells expressing low receptor numbers were transfected with a plasmid vector expressing IGF-I receptor cDNA in which single or multiple tyrosine codons in the kinase domain, namely Tyr-1131, Tyr-1135, and Tyr-1136 or the C-terminal tyrosines 1250 and 1251 were substituted with phenylalanine. Changes in the invasive and metastatic properties were analyzed relative to M-27 cells expressing the wild type receptor. We found that cells expressing the Y1131F,Y1135F,Y1136F or Y1135F receptor mutants lost all IGF-IR-dependent functions and their phenotypes were indistinguishable from, or suppressed relative to, the parent line. The Y1250F,Y1251F substitution abolished anchorage-independent growth, cell spreading, and the anti-apoptotic effect of IGF-I whereas all other IGF-IR-dependent phenotypes were either unperturbed (i.e. mitogenicity) or only partially reduced (migration and invasion). The results identify three types of receptor-dependent functions in this model: those dependent only on an intact kinase domain (DNA synthesis), those dependent equally on kinase domain and Tyr-1250/1251 signaling (e.g. apoptosis, soft agar cloning) and those dependent on kinase domain and enhanced through Tyr-1250/1251 signaling (migration, invasion). They suggest that signals derived from both regions of the receptor cooperate to enhance tumor metastasis.Cancer metastasis is a complex multistep process involving sequential interactions between the disseminating tumor cells and a continuously changing host microenvironment. These interactions include cell-cell and cell-extracellular matrix communication mediated through specific adhesion receptors, such as integrins, which regulate tumor cell attachment, spreading, and migration (1, 2), the dissolution of tissue barriers through the degradative activity of enzymes such as metallo-and serine-proteinases (3, 4) and growth modulation by paracrine, host-derived peptide growth factors (5, 6).The human receptor for the type 1 insulin-like growth factor (IGF-IR) 1 is a heterotetramer consisting of two 130-to 135-kDa ␣ and two 90-to 95-kDa ␤ subunits with several ␣-␣ and ␣-␤ disulfide bridges (7). It is synthesized as a single polypeptide chain, which is then glycosylated and proteolytically cleaved into the ␣ and ␤ subunits (8). The ligand-binding domain is located on the extracellular ␣ subunit. Approximately one-third of the ␤ subunit is extracellular and is connected to the intracellular portion by a single transmembrane domain. The intracellular region of the ␤ subuni...

Increased insulin-like growth factor-1 receptor mRNA expression predicts poor survival in immunophenotypes of early breast carcinoma

“…Previous mutational analysis studies have shown that signals derived from both regions of the IGF1R cooperate to enhance tumor metastasis. 15 Moreover, a relationship between local recurrence and radioresistance due to mutations at the C-terminal domain 43 could not be confirmed in our former study. 30 So far, no other previous investigators have analyzed the importance of IGF1R mRNA levels or IGF1R mutation status on breast carcinoma subtypes for a comparison with our data.…”

“…[9][10][11][12] Recent epidemiological and clinico-pathological data have supported the role of the insulin-like growth factor-1 (IGF1R) signaling system on tumor development and progression. [13][14][15][16][17] In breast carcinoma, high levels of IGF1R have been detected in 30-82%, 18,19 but its prognostic value is controversial. [20][21][22][23][24][25][26][27] Emerging experimental and clinical data suggest that the IGF1R and ER/PR pathways are interactive.…”

Type IV collagen-initiated signals provide survival and growth cues required for liver metastasis

“…Previously, we identified the IGF-IR as a key regulator of the liver-metastasizing phenotype in a Lewis lung carcinoma-based model of organ site-specific metastasis (Brodt et al, 2001;Samani et al, 2004). The present study was prompted by our finding, based on gene chip microarray analysis, that in this model, the acquisition of a liver-metastasizing phenotype was associated with markedly increased type IV collagen a1 and a2 expression levels.…”

“…Identification of genes differentially expressed in IGF-IR-overexpressing tumor cells that acquired a liver-metastasizing potential Previously, we reported that lung-metastasizing M-27 cells that were stably transfected with a full-length hIGF-IR complementary (c)DNA (M-27 IGFÀIR ) acquired a liver-colonizing potential (Brodt et al, 2001). We show here that the increase in their liver-colonizing potential, as seen following intrasplenic injection of the cells (representative histology shown in Figure 1a), was associated with major changes to gene expression in these cells, as revealed by Affymetrix gene chip analysis and depicted in the heat map shown in Figure 1b (with full list shown in Supplementary Table 1).…”

Dysregulation of growth factor signaling in human hepatocellular carcinoma

“…dnIGF-1R isoforms with deletions in the cytoplasmic tyrosine kinase domain such as dnIGF-1R 950 and dnIGF-1R 952 Min et al, 2003Min et al, , 2005 and also secreted isoforms like dnIGF-1R 486 and dnIGF-1R 482 (Reiss et al, 1998(Reiss et al, , 2001Min et al, 2003) mediate antineoplastic effects based on the induction of tumor cell apoptosis and growth inhibition. Moreover, specific mutations in the important carboxy-terminal domain (Tyr1250 and Tyr1251) and the tyrosine kinase domain (Tyr1131, Tyr1135 and Tyr1136) reduce proliferation, tumor cell survival and migration (Gronborg et al, 1993;Baserga et al, 1997;Brodt et al, 2001). Several investigators also employed antisense RNA and antisense oligodeoxynucleotide techniques to block IGF-1R synthesis (Trojan et al, 1993;Resnicoff et al, 1994Resnicoff et al, , 1995Lafarge-Frayssinet et al, 1997), leading to increased apoptosis and reduced proliferation.…”