The inhibition of chloride intracellular channel 1 enhances Ca2+ and reactive oxygen species signaling in A549 human lung cancer cells.

Abstract

Chloride intracellular channel 1 (CLIC1) is a promising therapeutic target in cancer due to its intrinsic characteristics; it is overexpressed in specific tumor types and its localization changes from cytosolic to surface membrane depending on activities and cell cycle progression. Ca2+ and reactive oxygen species (ROS) are critical signaling molecules that modulate diverse cellular functions, including cell death. In this study, we investigated the function of CLIC1 in Ca2+ and ROS signaling in A549 human lung cancer cells. Depletion of CLIC1 via shRNAs in A549 cells increased DNA double-strand breaks both under control conditions and under treatment with the putative anticancer agent chelerythrine, accompanied by a concomitant increase in the p-JNK level. CLIC1 knockdown greatly increased basal ROS levels, an effect prevented by BAPTA-AM, an intracellular calcium chelator. Intracellular Ca2+ measurements clearly showed that CLIC1 knockdown significantly increased chelerythrine-induced Ca2+ signaling as well as the basal Ca2+ level in A549 cells compared to these levels in control cells. Suppression of extracellular Ca2+ restored the basal Ca2+ level in CLIC1-knockdown A549 cells relative to that in control cells, implying that CLIC1 regulates [Ca2+]i through Ca2+ entry across the plasma membrane. Consistent with this finding, the L-type Ca2+ channel (LTCC) blocker nifedipine reduced the basal Ca2+ level in CLIC1 knockdown cells to that in control cells. Taken together, our results demonstrate that CLIC1 knockdown induces an increase in the intracellular Ca2+ level via LTCC, which then triggers excessive ROS production and consequent JNK activation. Thus, CLIC1 is a key regulator of Ca2+ signaling in the control of cancer cell survival.

• Authors: Jae-Rin Lee, Jong-Yoon Lee, Hyun-Ji Kim, Myong-Joon Hahn, Jong-Sun Kang, Hana Cho
• Journal: Experimental & molecular medicine (Exp Mol Med) Vol. 51 Issue 7 Pg. 1-11 (07 17 2019) ISSN: 2092-6413 [Electronic] United States
• PMID: 31316050 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• CLIC1 protein, human
• Chloride Channels
• RNA, Small Interfering
• Reactive Oxygen Species
• Calcium

Topics

• A549 Cells
• Calcium (metabolism)
• Calcium Signaling (drug effects)
• Cell Death
• Cell Membrane (metabolism)
• Chloride Channels (antagonists & inhibitors, metabolism)
• DNA Breaks, Double-Stranded
• Gene Knockdown Techniques
• Humans
• Lung Neoplasms (drug therapy, metabolism)
• RNA, Small Interfering (genetics)
• Reactive Oxygen Species (antagonists & inhibitors, metabolism)