NAIF1 is down-regulated in gastric cancer and promotes apoptosis through the caspase-9 pathway in human MKN45 cells

Abstract

Abstract. Many key proteins are down-regulated or lose their function during cancer genesis and accelerate the progress of cancer. We found that nuclear apoptosis-inducing factor 1 (nAIF1) was highly expressed in normal gastric tissues but was down-regulated or lost in gastric cancer tissues (p<0.001). nAIF1 expression was higher in well-differentiated (p=0.004) than in moderately-or poorly-differentiated gastric cancer. nAIF1 expression was associated with different t stages (p=0.024). In vitro, nAIF1 can inhibit tumor cell proliferation and induce g0/g1 phase cell cycle arrest in the MKn45 cell line. nAIF1 can induce apoptosis through activation of procaspase-9 rather than procaspase-8 followed by activation of the caspase-3 pathway. We designed and constructed two truncation mutants, pegFpn1-nls and pegFp-n1-grr, and identified the n-terminal 1-90 amino acid domain of nAIF1, which is a helix-turn-helix motif and which was sufficient for inducing apoptosis. Therefore, these findings suggest that NAIF1 plays an inhibitory role in the initial steps of gastric cancer genesis and may provide new strategies for developing anti-cancer drugs using small molecular polypeptides. Introductiongastric cancer is a highly frequent malignancy worldwide with an estimated incidence of 934000 new cases per year in 2002 (1,2). More than 42% of gc patients are found in china alone (3). currently, targeted therapies designed to induce apoptosis in cancer cells selectively are the most promising anti-cancer strategies. Many efforts have been made to cure gastric cancer, most of which based on developing effective apoptotic therapeutic approaches such as activation of cell surface death receptors, inhibition of cell survival signaling and others (4-6).nAIF1 (nuclear apoptosis-inducing factor 1) was found to induce apoptosis when overexpressed in Hela and HeK293 cells (7). Another study showed nAIF1 was related to transposition because of its trihelix motif (8). However, little information exists on the relationship between nAIF1 and cancer genesis and progress, thus this study investigated the expression and function of nAIF1 in cancer.We found nAIF1 was highly expressed in normal stomach tissue, but was down-regulated or lost in gastric cancer tissue (P<0.001). This event significantly correlated with the tumor differential t stage. Functional studies indicated nAIF1 can reduce cell viability in human gastric cell line MKn45 by g0/g1 phase cell cycle arrest and induce apoptosis 48 h posttransfection. Western blot analysis indicated nAIF1 triggered procaspase-3 and procaspase-9 activation and pArp cleavage in MKN45. Furthermore, we identified that the 1-90 amino acids domain was the core functional domain of nAIF1 for inducing apoptosis. Thus, our findings provide a potential target for gc apoptotic therapeutic approach. Materials and methodsReagents. Mtt, pI and DApI were purchased from sigma (UsA). Monoclonal antibody against β-actin was purchased from sigma-Aldrich (UsA). the antibody against pArp and procaspase-8 were purchased ...

Overexpression of Nuclear Apoptosis-Inducing Factor 1 Altered the Proteomic Profile of Human Gastric Cancer Cell MKN45 and Induced Cell Cycle Arrest at G1/S Phase

“…The data presented herein is analogous to Luo's finding in tissues [10]. Moreover, we confirmed that NAIF1 is a nuclear protein in the gastric cancer cell lines MKN45 and BGC823.…”

“…The expression plasmids pEGFP-N1-NAIF1, which expresses a NAIF1-GFP fusion protein, and pEGFP-N1, which expresses green fluorescent protein (GFP), was kindly provided by Dr. Qing Luo [10].…”

“…NAIF1 encodes a protein with a Myb -like domain at its N-terminal region [8], [9]. Previous studies have shown that overexpression of NAIF1 in human cancer cell lines HeLa and MKN45 induces apoptosis [8], [10]. Moreover, Luo et al found that NAIF1 is significantly expressed in normal gastric tissue, while its expression is down-regulated or lost in gastric cancer tissues ( P< 0.001).…”

“…Moreover, Luo et al found that NAIF1 is significantly expressed in normal gastric tissue, while its expression is down-regulated or lost in gastric cancer tissues ( P< 0.001). In addition, NAIF1 expression was higher in well-differentiated ( P  = 0.004) than in moderately- or poorly-differentiated gastric cancer [10]. However, the role of NAIF1 in regulating the cellular protein expression profile is unknown.…”

MicroRNA-125a-5p regulates cancer cell proliferation and migration through NAIF1 in prostate carcinoma

“…In gastric cancer, NAIF1 inhibits gastric cancer migration and invasion by targeting MAPK or caspase-3. 13 , 14 In non-small-cell lung cancer, NAIF1 interacts with miR-24 to inhibit cancer growth. 15 In human prostate cancer, NAIF1 was suggested to be a potential biomarker, 16 yet its exact expression pattern or functional role remains elusive.…”