Aminoacylase 3 Is a New Potential Marker and Therapeutic Target in Hepatocellular Carcinoma

Kirill Tsirulnikov; Sergio Duarte; Anamika Ray; Nakul Datta; Ali Zarrinpar; Lin Hwang; Kym Faull; Alexander Pushkin; Ira Kurtz

doi:10.7150/jca.21747

Aminoacylase 3 Is a New Potential Marker and Therapeutic Target in Hepatocellular Carcinoma

J Cancer. 2018 Jan 1;9(1):1-12. doi: 10.7150/jca.21747. eCollection 2018.

Authors

Kirill Tsirulnikov¹, Sergio Duarte², Anamika Ray^{3

4}, Nakul Datta³, Ali Zarrinpar^{3

5}, Lin Hwang⁶, Kym Faull^{6

7}, Alexander Pushkin¹, Ira Kurtz^{1

7}

Affiliations

¹ Division of Nephrology, Department of Medicine, D. Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA.
² Dumont-UCLA Transplant Center, D. Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA.
³ Department of Surgery, D. Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA.
⁴ Current address: InnoSense LLC, Torrance, CA, USA.
⁵ Current address: Division of Transplantation and Hepatobiliary Surgery, Department of Surgery, College of Medicine, University of Florida, Gainesville, FL, USA.
⁶ Pasarow Mass Spectrometry Laboratory, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, USA.
⁷ Brain Research Institute, University of California at Los Angeles, Los Angeles, CA, USA.

Abstract

Ras proteins (HRas, KRas and NRas) are common oncogenes that require membrane association for activation. Previous approaches to block/inhibit Ras membrane association were unsuccessful for cancer treatment in human clinical studies. In the present study we utilized a new approach to decrease Ras membrane association in hepatocellular carcinoma (HCC) cell lines via inhibition of an enzyme aminoacylase 3 (AA3; EC 3.5.1.114). AA3 expression was significantly elevated in the livers of HCC patients and HCC cell lines. Treatment of HepG2 cells with AA3 inhibitors, and HepG2 and HuH7 with AA3 siRNA significantly decreased Ras membrane association and was toxic to these HCC cell lines. AA3 inhibitors also increased the levels of N-acetylfarnesylcysteine (NAFC) and N-acetylgeranylgeranylcysteine (NAGGC) in HepG2 and Huh7 cell lines. We hypothesized that AA3 deacetylates NAFC and NAGGC, and generated farnesylcysteine (FC) and geranylgeranylcysteine (GGC) that are used in HCC cells for the regeneration of farnesylpyrophosphate and geranylgeranylpyrophosphate providing the prenyl (farnesyl or geranylgeranyl) group for Ras prenylation required for Ras membrane association. This was confirmed experimentally where purified human AA3 was capable of efficiently deacetylating NAFC and NAGGC. Our findings suggest that AA3 inhibition may be an effective approach in the therapy of HCC and that elevated AA3 expression in HCC is potentially an important diagnostic marker.

Keywords: Ras prenylation; aminoacylase 3.; hepatocellular carcinoma.