CAPN1 is a novel binding partner and regulator of the tumor suppressor NF1 in melanoma

Michal Alon, Rand Arafeh, Joo Sang Lee, Sanna Madan, Shelly Kalaora, Adi Nagler, Tereza Abgarian, Polina Greenberg, Eytan Ruppin, Yardena Samuels

Research output: Contribution to journalArticlepeer-review

Abstract

Neurofibromin 1 (NF1), a tumor suppressor that negatively regulates RAS through its GTPase activity, is highly mutated in various types of sporadic human cancers, including melanoma. However, the binding partners of NF1 and the pathways in which it is involved in melanoma have not been characterized in an in depth manner. Utilizing a mass spectrometry analysis of NF1 binding partners, we revealed Calpain1 (CAPN1), a calcium-dependent neutral cysteine protease, as a novel NF1 binding partner that regulates NF1 degradation in melanoma cells. ShRNA-mediated knockdown of CAPN1 or treatment with a CAPN1 inhibitor stabilizes NF1 protein levels, downregulates AKT signaling and melanoma cell growth. Combination treatment of Calpain inhibitor I with MEKi Trametinib in different melanoma cells is more effective in reducing melanoma cell growth compared to treatment with Trametinib alone, suggesting that this combination may have a therapeutic potential in melanoma. This novel mechanism for regulating NF1 in melanoma provides a molecular basis for targeting CAPN1 in order to stabilize NF1 levels and, in doing so, suppressing Ras activation; this mechanism can be exploited therapeutically in melanoma and other cancers.

Original languageEnglish
Pages (from-to)31264-31277
Number of pages14
JournalOncotarget
Volume9
Issue number58
DOIs
StatePublished - 27 Jul 2018
Externally publishedYes

Keywords

  • CAPN1
  • Combination therapy
  • Degradation
  • Melanoma
  • NF1

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