Abstract 4854: PKM2 Modulates hepatic macrophage regulation of NASH, ferroptosis and HCC through TGF-β signaling
Authors: Ohshiro Kazufumi , Bhowmick Krishanu , Yang Xiaochun , Klebanov Addison , John Sahara , Voss Dillon , Krainer Adrian , Mishra Lopa 
Published: April 2023

Background: Non-alcoholic steatohepatitis (NASH) and cirrhosis are major risk factors for hepatocellular carcinoma (HCC), which affects men 2-4 times more than women. In tumors Pyruvate kinase M2 (PKM2), induces aerobic glycolysis (Warburg effect) and proinflammatory and non-apoptotic cell death, ferroptosis. Raised levels of hepatic macrophage PKM2 expression are associated with poor prognosis HCC. We previously found that liver specific TGF-β/SMAD4 knockout mice develop iron deposition and hemochromatosis due to a dramatic loss of hepcidin. Moreover, Smad4+/−Sptbn1+/− mice develop gastrointestinal cancers but only in the presence of an altered microbiome. Recently, we found that liver-specific knockout of a TGF-β/SMAD3/4 adaptor protein, βII-spectrin (LSKO) blocks diet-induced NASH and HCC in mice, as well as in siRNA treated human NASH microfluidic cultures (Sci Transl Med. 2021;13(624): eabk2267). We hypothesized that βII-spectrin modulates PKM2 expression in NASH fatty liver, promoting proinflammatory cytokine release, inflammation and tumorigenesis. In addition, microbiome changes could alter hepcidin function and modulate ferroptosis. Our goal is to understand the molecular mechanism underlying PKM2 driven NASH and HCC.

Methods: For our NASH mouse model, we fed SPTBN1Flox (control) and liver-specific βII-spectrin knockout (SPTBN1LSKO) mice a Western diet (WD). Body weight, total cholesterol, and triglyceride concentrations in serum were monitored, and PKM2 expression levels in the liver tissues was analyzed. SPTBN1Flox and SPTBN1LSKO mice were treated with both WD and Diethylnitrosamine (DEN) for HCC, and gut microbiome profiles were performed in these mice. To evaluate PKM2 expression in the NASH-associated HCC mouse model, immunohistochemical labeling was performed on liver tissues of these mice with PKM2-specific antibody. Inflammation, lipidosis and fibrosis were determined with H&E, Oil Red O and Sirius Red staining.

Results: We found upregulation of PKM2 expression in NASH and HCC Kupffer cells (WD SPTBN1Flox mice). In contrast, PKM2 expression was markedly reduced in the liver in WD SPTBN1LSKO that blocked NASH and HCC. Interestingly, microbiome profiles were altered and TGF-β/SMAD3-regulated fibrosis as well as expression of inflammatory genes were significantly reduced in LSKO mice, compared to the NASH mice.

Conclusions: Our findings suggest that the knockdown of the Smad3/4 adaptor βII-spectrin decreases PKM2 expression in Kupffer cells, thereby suppressing pro-inflammatory cytokine production, blocking NASH-associated HCC. Hepatic macrophages such as Kupffer cells and monocyte-derived macrophages could therefore play a critical role in the ferroptosis-mediated protumor immune microenvironment. In addition, our work provides new insight into potential mechanism for two disorders that affect males more than females, hemochromatosis and HCC.

Citation Format: Kazufumi Ohshiro, Krishanu Bhowmick, Xiaochun Yang, Addison Klebanov, Sahara John, Dillon Voss, Adrian Krainer, Lopa Mishra. PKM2 Modulates hepatic macrophage regulation of NASH, ferroptosis and HCC through TGF-β signaling. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4854.