Abstract LB-41: Regulation of adhesion, motility, and invasion by insulin-like growth factor-2 binding protein 3 in pancreatic cancer cells
Authors: Clarissa Pasiliao, Che-Wei Chang, Brent Sutherland, Shannon Valdez, Donald Yapp, Sylvia Ng
Journal: Cancer Research (2011)

Abstract Background: Overexpression of insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3 or IMP3), a member of the VICKZ family of RNA-binding proteins, has been correlated with poor prognosis in pancreatic cancer and other cancer types, including lung, bladder, kidney, liver, and prostate. In human leukemia cells as well as in HeLa and hepatocellular carcinoma cells, IMP3 has previously been shown to regulate a number of cellular functions. However, the role of this oncofetal protein in pancreatic cancer progression remains to be elucidated. In the present study, we characterized the effect of IMP3 inhibition on the proliferation, motility, adhesion, and invasive potential of pancreatic cancer cells. Methods: IMP3 levels in Panc-1 and Hs766T were decreased through RNA interference. Untreated and scramble-siRNA transfected cells were used as controls. The effect of knockdown on cellular behavior was evaluated 48 h after transfection. Proliferation was assessed using the MTS assay, while a commercially-available colorimetric assay was used to assess adhesion to extracellular matrix proteins. Motility and invasive potential were evaluated using the Boyden chamber assay. Data were analyzed using repeated measures ANOVA. Significant F ratios were further examined using the Tukey post-hoc test. Results: The basal levels of IMP3 were found to be similar in Panc1 and Hs766T cells. IMP3 siRNA knockdown reduced IMP3 protein levels by 48% relative to scramble siRNA control. In both cell lines, a decrease in IMP3 did not significantly affect proliferation when compared to scramble siRNA-treated control. Interestingly, knockdown of IMP3 reduced the adhesion of Hs766T to fibronectin (20%; P &amp;lt; 0.05), tenascin (23%; P &amp;lt; 0.05), collagen IV (30%; P &amp;lt; 0.01), laminin (18%; P &amp;lt; 0.01), and vitronectin (51%, P &amp;lt; 0.01) relative to scramble siRNA control. Adhesion of Hs766T to collagen I and collagen IV) was unaffected. Moreover, relative to scramble siRNA control, the suppression of IMP3 expression in Hs766T reduced motility by 30% (P &amp;lt; 0.05) and cellular invasion through Matrigel by 80% (P &amp;lt; 0.05). In contrast, knockdown of IMP3 did not alter the adhesion, motility, and invasive potential of Panc1 cells compared to scramble siRNA control. Conclusion: Our preliminary results demonstrated that IMP3 differentially regulates cellular adhesion and invasive potential of pancreatic cancer cell lines, suggesting that this oncofetal protein may play a role in tumor metastasis. In line with this hypothesis, we are currently examining the role of IMP3 in regulating the phenotype of L3.6pl, a pancreatic cancer cell line characterized to exhibit metastatic potential. In addition, studies are currently underway to identify the downstream molecular target(s) of IMP3 that may mediate metastasis of pancreatic cancer cells. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-41. doi:10.1158/1538-7445.AM2011-LB-41