Store-Operated Ca2+ Entry (SOCE) Regulates Melanoma Proliferation and Cell Migration

Masanari Umemura,Mariana S De Lorenzo,Yoshihiro Ishikawa,Kayoko Oda,Ayako Makino,Stefan Feske,Mizuka Iwatsubo,Kousaku Iwatsubo,Takayuki Fujita,James S Goydos,Suzie Chen,Xianfeng Feng,Lai-Hua Xie,Utako Yokoyama,Erdene Baljinnyam,Laszlo Csernoch

doi:10.1371/journal.pone.0089292

Abstract

Store-operated Ca2+ entry (SOCE) is a major mechanism of Ca2 + import from extracellular to intracellular space, involving detection of Ca2+ store depletion in endoplasmic reticulum (ER) by stromal interaction molecule (STIM) proteins, which then translocate to plasma membrane and activate Orai Ca2+ channels there. We found that STIM1 and Orai1 isoforms were abundantly expressed in human melanoma tissues and multiple melanoma/melanocyte cell lines. We confirmed that these cell lines exhibited SOCE, which was inhibited by knockdown of STIM1 or Orai1, or by a pharmacological SOCE inhibitor. Inhibition of SOCE suppressed melanoma cell proliferation and migration/metastasis. Induction of SOCE was associated with activation of extracellular-signal-regulated kinase (ERK), and was inhibited by inhibitors of calmodulin kinase II (CaMKII) or Raf-1, suggesting that SOCE-mediated cellular functions are controlled via the CaMKII/Raf-1/ERK signaling pathway. Our findings indicate that SOCE contributes to melanoma progression, and therefore may be a new potential target for treatment of melanoma, irrespective of whether or not Braf mutation is present.

Highlights

Melanoma has the poorest prognosis among skin cancers, drugs targeting aberrant extracellular-signal-regulated kinase (ERK) signaling, i.e., mutated serine/threonine-protein kinase Braf, have improved both overall and progression-free survival times [1]
We show that Store-operated Ca2+ entry (SOCE) promotes melanoma progression by enhancing cell proliferation, migration, and metastasis through activation of ERK signaling via the calmodulin kinase II (CaMKII)/Raf-1/ERK pathway
Western blot analyses showed that STIM1 and Orai1 are expressed in metastatic human melanoma cell lines, while the melanocyte cell line, HEMA-LP, displayed only a low level of Orai1 expression (Fig. 1A and B)

Summary

Introduction

Melanoma has the poorest prognosis among skin cancers, drugs targeting aberrant ERK signaling, i.e., mutated serine/threonine-protein kinase Braf, have improved both overall and progression-free survival times [1]. This therapy is not effective in patients without Braf mutation, and some patients with Braf mutation rapidly acquire resistance to Braf inhibitors [2]. Intracellular Ca2+ signaling regulates diverse cellular functions including proliferation and cell migration [3]. Store-operated Ca2+ entry (SOCE) is a major mechanism of Ca2+ import from extracellular to intracellular space, especially in non-excitable cells [4]. The resulting decrease of Ca2+ concentration in the ER is sensed by the EF-hand motif of stromal interaction molecules (STIM), which translocate to the plasma membrane, where they interact with Orai Ca2+ channel subunits [5], leading to Ca2+ influx from extracellular space to restore the Ca2+ concentration in ER [6]

Methods

Results

Conclusion