Stim and Orai mediate constitutive Ca2+ entry and control endoplasmic reticulum Ca2+ refilling in primary cultures of colorectal carcinoma cells
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Estella Zuccolo1,*, Umberto Laforenza2,*, Federica Ferulli3,*, Giorgia Pellavio2, Giorgia Scarpellino1, Matteo Tanzi3, Ilaria Turin3, Pawan Faris1,4, Angela Lucariello5, Marcello Maestri6, Dlzar Ali Kheder1,7, Germano Guerra5, Paolo Pedrazzoli8, Daniela Montagna3,9,** and Francesco Moccia1,**
1Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, Pavia, Italy
2Department of Molecular Medicine, University of Pavia, Pavia, Italy
3Laboratory of Immunology Transplantation, Foundation IRCCS Policlinico San Matteo, Pavia, Italy
4Department of Biology, College of Science, Salahaddin University, Erbil, Kurdistan-Region of Iraq, Iraq
5Department of Medicine and Health Sciences “Vincenzo Tiberio”, University of Molise, Campobasso, Italy
6Unit of General Surgery, Foundation IRCCS Policlinico San Matteo, Pavia, Italy
7Department of Biology, University of Zakho, Zakho, Kurdistan-Region of Iraq, Iraq
8Medical Oncology, Foundation IRCCS Policlinico San Matteo, Pavia, Italy
9Department of Sciences Clinic-Surgical, Diagnostic and Pediatric, University of Pavia, Pavia, Italy
*These authors have contributed equally to this work
**These authors share senior authorship of the manuscript
Francesco Moccia, email: email@example.com
Daniela Montagna, email: firstname.lastname@example.org
Keywords: colorectal cancer; store-operated Ca2+ entry; Stim; Orai; proliferation
Received: March 07, 2018 Accepted: June 23, 2018 Published: July 24, 2018
Store-operated Ca2+ entry (SOCE) provides a major Ca2+ entry route in cancer cells. SOCE is mediated by the assembly of Stim and Orai proteins at endoplasmic reticulum (ER)-plasma membrane junctions upon depletion of the ER Ca2+ store. Additionally, Stim and Orai proteins underpin constitutive Ca2+ entry in a growing number of cancer cell types due to the partial depletion of their ER Ca2+ reservoir. Herein, we investigated for the first time the structure and function of SOCE in primary cultures of colorectal carcinoma (CRC) established from primary tumor (pCRC) and metastatic lesions (mCRC) of human subjects. Stim1-2 and Orai1-3 transcripts were equally expressed in pCRC and mCRC cells, although Stim1 and Orai3 proteins were up-regulated in mCRC cells. The Mn2+-quenching technique revealed that constitutive Ca2+ entry was significantly enhanced in pCRC cells and was inhibited by the pharmacological and genetic blockade of Stim1, Stim2, Orai1 and Orai3. The larger resting Ca2+ influx in pCRC was associated to their lower ER Ca2+ content as compared to mCRC cells. Pharmacological and genetic blockade of Stim1, Stim2, Orai1 and Orai3 prevented ER-dependent Ca2+ release, thereby suggesting that constitutive SOCE maintains ER Ca2+ levels. Nevertheless, pharmacological and genetic blockade of Stim1, Stim2, Orai1 and Orai3 did not affect CRC cell proliferation and migration. These data provide the first evidence that Stim and Orai proteins mediate constitutive Ca2+ entry and replenish ER with Ca2+ in primary cultures of CRC cells. However, SOCE is not a promising target to design alternative therapies for CRC.
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