tolfenamic-acid and Cell-Transformation--Neoplastic

Several diseases are associated with improper regulation of the Hippo pathway, which plays an important role in cell proliferation and cancer metastasis. Overactivation of the YAP and TAZ proteins accelerates cell proliferation, invasion, and migration during tumorigenesis. Tolfenamic acid (TA) is a non-steroidal anti-inflammatory drug (NSAID) that exhibits activity against various types of cancer. In this study, we observed that TA decreased YAP and TAZ protein levels in cancer cells. TA increased the phosphorylation of YAP and TAZ, leading to the degradation of YAP and TAZ in the cytoplasm and nucleus. TA predominantly affected multiple phosphodegron sites in the YAP and TAZ and lowered 14-3-3β protein expression, causing YAP and TAZ to enter the ubiquitination pathway. Proteins that affect YAP and TAZ regulation, such as NAG-1 and several YAP/TAZ E3 ligases, were not involved in TA-mediated YAP/TAZ degradation. In summary, our results indicate that TA affects phosphodegron sites on YAP/TAZ, demonstrating a novel effect of TA in tumorigenesis.

Topics: Adaptor Proteins, Signal Transducing; Carcinogenesis; Cell Transformation, Neoplastic; Humans; Trans-Activators; Transcription Factors; YAP-Signaling Proteins

The nonsteroidal anti-inflammatory drug tolfenamic acid has been shown to suppress cancer cell growth and tumorigenesis in different cancer models. However, the underlying mechanism by which tolfenamic acid exerts its antitumorigenic effect remains unclear. Previous data from our group and others indicate that tolfenamic acid alters expression of apoptosis- and cell-cycle arrest-related genes in colorectal cancer cells. Here, we show that tolfenamic acid markedly reduced the number of polyps and tumor load in APC(min)(/+) mice, accompanied with cyclin D1 downregulation in vitro and in vivo. Mechanistically, tolfenamic acid promotes endoplasmic reticulum (ER) stress, resulting in activation of the unfolded protein response (UPR) signaling pathway, of which PERK-mediated phosphorylation of eukaryotic translation initiation factor 2α (eIF2α) induces the repression of cyclin D1 translation. Moreover, the PERK-eIF2α-ATF4 branch of the UPR pathway plays a role in tolfenamic acid-induced apoptosis in colorectal cancer cells, as silencing ATF4 attenuates tolfenamic acid-induced apoptosis. Taken together, these results suggest ER stress is involved in tolfenamic acid-induced inhibition of colorectal cancer cell growth, which could contribute to antitumorigenesis in a mouse model.

Topics: Activating Transcription Factor 4; Adenomatous Polyposis Coli Protein; Animals; Anti-Inflammatory Agents, Non-Steroidal; Blotting, Western; Cell Transformation, Neoplastic; Colonic Polyps; Colorectal Neoplasms; Cyclin D1; eIF-2 Kinase; Endoplasmic Reticulum Stress; Humans; Immunoprecipitation; Mice; Mice, Inbred C57BL; Mice, Knockout; ortho-Aminobenzoates; Phosphorylation; Protein Serine-Threonine Kinases; Real-Time Polymerase Chain Reaction; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; Tumor Cells, Cultured; Unfolded Protein Response