Transglutaminase 2 promotes tumorigenicity of colon cancer cells by inactivation of the tumor suppressor p53

Patrizia Malkomes,Stefan Günther,Frank Schnütgen,Can Canbulat,Hubert Serve,Katharina Holzer,Weijia Yu,Marina S Dietz,Nadine Haetscher,Claudia Catapano,Thomas Oellerich,Hans‐Michael Kvasnicka ,Elsie Oppermann,Wolf O Bechstein ,Mike Heilemann,Ilaria Lunger,Sabrina Bothur,Khalil Abou-El-Ardat,Susanne Wingert,Michael A Rieger

doi:10.1038/s41388-021-01847-w

Abstract

Despite a high clinical need for the treatment of colorectal carcinoma (CRC) as the second leading cause of cancer-related deaths, targeted therapies are still limited. The multifunctional enzyme Transglutaminase 2 (TGM2), which harbors transamidation and GTPase activity, has been implicated in the development and progression of different types of human cancers. However, the mechanism and role of TGM2 in colorectal cancer are poorly understood. Here, we present TGM2 as a promising drug target.In primary patient material of CRC patients, we detected an increased expression and enzymatic activity of TGM2 in colon cancer tissue in comparison to matched normal colon mucosa cells. The genetic ablation of TGM2 in CRC cell lines using shRNAs or CRISPR/Cas9 inhibited cell expansion and tumorsphere formation. In vivo, tumor initiation and growth were reduced upon genetic knockdown of TGM2 in xenotransplantations. TGM2 ablation led to the induction of Caspase-3-driven apoptosis in CRC cells. Functional rescue experiments with TGM2 variants revealed that the transamidation activity is critical for the pro-survival function of TGM2. Transcriptomic and protein–protein interaction analyses applying various methods including super-resolution and time-lapse microscopy showed that TGM2 directly binds to the tumor suppressor p53, leading to its inactivation and escape of apoptosis induction.We demonstrate here that TGM2 is an essential survival factor in CRC, highlighting the therapeutic potential of TGM2 inhibitors in CRC patients with high TGM2 expression. The inactivation of p53 by TGM2 binding indicates a general anti-apoptotic function, which may be relevant in cancers beyond CRC.

Highlights

These authors contributed : Patrizia Malkomes, Ilaria Lunger
After confirming the specificity of the monoclonal antibody against Transglutaminase 2 (TGM2) (Supplementary Fig. S1), we demonstrated that TGM2 was expressed to a higher extent in epithelial cancer tissue than in matched normal colon epithelium in all investigated cases (Fig. 1A, B, Supplementary Fig. S2)
Since we showed the rapid induction of Caspase-3-dependent apoptosis upon TGM2 inactivation, we further focused on the p53 pathway

Summary

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Fernández-Acenero et al found that high TGM2 expression in the stroma is associated with increased relapse risk in CRC, showing the potential of TGM2 as a prognostic marker [28] It remains uncertain, whether TGM2 has a pro- or antitumorigenic role [29, 30], if it promotes tumor cell survival or apoptosis [31, 32], and whether epithelial–mesenchymal transition and invasion are supported by TGM2 [33,34,35,36]. To resolve some of these long-standing questions, we determined the expression and activity of TGM2 in primary patient material and accurately investigated the functional mechanism of TGM2 in CRC including preclinical mouse models and mechanistic in vitro studies at single cell level. Our data demonstrate that TGM2 is essential for CRC cell survival by direct interaction with p53 that might be involved in the pathogenesis of colon cancer

Results

Discussion

Materials and methods

Compliance with ethical standards