TMX2 potentiates cell viability of hepatocellular carcinoma by promoting autophagy and mitophagy

ABSTRACT

The dysregulation of membrane protein expression has been implicated in tumorigenesis and progression, including hepatocellular carcinoma (HCC). In this study, we aimed to identify membrane proteins that modulate HCC viability. To achieve this, we performed a CRISPR activation screen targeting human genes encoding membrane-associated proteins, revealing TMX2 as a potential driver of HCC cell viability. Gain- and loss-of-function experiments demonstrated that TMX2 promoted growth and tumorigenesis of HCC. Clinically, TMX2 was an independent prognostic factor for HCC patients. It was significantly upregulated in HCC tissues and associated with poor prognosis of HCC patients. Mechanistically, TMX2 was demonstrated to promote macroautophagy/autophagy by facilitating KPNB1 nuclear export and TFEB nuclear import. In addition, TMX2 interacted with VDAC2 and VADC3, assisting in the recruitment of PRKN to defective mitochondria to promote cytoprotective mitophagy during oxidative stress. Most interestingly, HCC cells responded to oxidative stress by upregulating TMX2 expression and cell autophagy. Knockdown of TMX2 enhanced the anti-tumor effect of lenvatinib. In conclusion, our findings emphasize the pivotal role of TMX2 in driving the HCC cell viability by promoting both autophagy and mitophagy. These results suggest that TMX2 May serve as a prognostic marker and promising therapeutic target for HCC treatment.

Abbreviation: CCCP: Carbonyl cyanide 3-chlorophenylhydrazone; Co-IP: co-immunoprecipitation; CRISPR: clustered regularly interspaced short palindromic repeat; ER: endoplasmic reticulum; HCC: hepatocellular carcinoma; KPNB1: karyopherin subunit beta 1; PRKN: parkin RBR E3 ubiquitin protein ligase; ROS: reactive oxygen species; TFEB: transcription factor EB; TMX2: thioredoxin related transmembrane protein 2; VDAC2: voltage dependent anion channel 2; VDAC3: voltage dependent anion channel 3; WB: western blot.

KEYWORDS:

• Autophagy
• CRISPR activation screening
• hepatocellular carcinoma (HCC)
• lenvatinib
• thioredoxin related transmembrane protein 2

Acknowledgements

We thank the Research Core Facility of Guangdong Provincial Engineering Research Center of Molecular Imaging.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Clinical information of samples and primers used in the present study can be found in Table S1 and S2. Other original data in our study are available upon request.

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15548627.2024.2358732.

Additional information

Funding

This work is supported by National Natural Science Foundation of China [82172241 and 82341066] and Guangdong-Hong Kong-Macao University Joint Laboratory of Interventional Medicine Foundation of Guangdong Province [2023LSYS001].