Raman spectroscopic imaging for investigations of de novo lipogenesis in hepatocellular carcinoma

Objective: In the rat, the pancreatic islet transplantation model is an established method to induce hepatocellular carcinomas (HCC), due to insulin-mediated metabolic and molecular alterations like increased glycolysis and de novo lipogenesis and the oncogenic AKT/mTOR pathway including upregulation of the transcription factor Carbohydrate-response element-binding protein (ChREBP). ChREBP could therefore represent an essential oncogenic co-factor during hormonally induced hepatocarcinogenesis. Methods: Pancreatic islet transplantation was implemented in diabetic C57Bl/6J (wild type, WT) and ChREBP-knockout (KO) mice for 6 and 12 months. Liver tissue was examined using histology, immunohistochemistry, electron microscopy and Western blot analysis. Finally, we performed NGS-based transcriptome analysis between WT and KO liver tumor tissues. Results: Three hepatocellular carcinomas were detectable after 6 and 12 months in diabetic transplanted WT mice, but only one in a KO mouse after 12 months. Pre-neoplastic clear cell foci (CCF) were also present in liver acini downstream of the islets in WT and KO mice. In KO tumors, glycolysis, de novo lipogenesis and AKT/mTOR signalling were strongly downregulated compared to WT lesions. Extrafocal liver tissue of diabetic, transplanted KO mice revealed less glycogen storage and proliferative activity than WT mice. From transcriptome analysis, we identified a set of transcripts pertaining to metabolic, oncogenic and immunogenic pathways that are differentially expressed between tumors of WT and KO mice. Of 315 metabolism-associated genes, we observed 199 genes that displayed upregulation in the tumor of WT mice, whereas 116 transcripts showed their downregulated expression in KO mice tumor. Conclusions: The pancreatic islet transplantation model is a suitable method to study hormonally induced hepatocarcinogenesis also in mice, allowing combination with gene knockout models. Our data indicate that deletion of ChREBP delays insulin-induced hepatocarcinogenesis, suggesting a combined oncogenic and lipogenic function of ChREBP along AKT/mTOR-mediated proliferation of hepatocytes and induction of hepatocellular carcinoma.

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Role of Lipogenesis Rewiring in Hepatocellular Carcinoma

Seminars in Liver Disease ◽

10.1055/s-0041-1731709 ◽

2021 ◽

Author(s):

Yi Zhou ◽

Junyan Tao ◽

Diego F. Calvisi ◽

Xin Chen

Keyword(s):

Hepatocellular Carcinoma ◽

De Novo ◽

Regulatory Element ◽

Critical Role ◽

De Novo Lipogenesis ◽

Enhanced Expression ◽

Sterol Regulatory Element ◽

Functional Analyses ◽

Transcription Factor 1

AbstractMetabolic rewiring is one of the hallmarks of cancer. Altered de novo lipogenesis is one of the pivotal metabolic events deregulated in cancers. Sterol regulatory element-binding transcription factor 1 (SREBP1) controls the transcription of major enzymes involved in de novo lipogenesis, including ACLY, ACACA, FASN, and SCD. Studies have shown the increased de novo lipogenesis in human hepatocellular carcinoma (HCC) samples. Multiple mechanisms, such as activation of the AKT/mechanistic target of rapamycin (mTOR) pathway, lead to high SREBP1 induction and the coordinated enhanced expression of ACLY, ACACA, FASN, and SCD genes. Subsequent functional analyses have unraveled these enzymes' critical role(s) and the related de novo lipogenesis in hepatocarcinogenesis. Importantly, targeting these molecules might be a promising strategy for HCC treatment. This paper comprehensively summarizes de novo lipogenesis rewiring in HCC and how this pathway might be therapeutically targeted.

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Combination of Mitochondrial and Plasma Membrane Citrate Transporter Inhibitors Inhibits De Novo Lipogenesis Pathway and Triggers Apoptosis in Hepatocellular Carcinoma Cells

BioMed Research International ◽

10.1155/2018/3683026 ◽

2018 ◽

Vol 2018 ◽

pp. 1-15 ◽

Cited By ~ 4

Author(s):

Wan-angkan Poolsri ◽

Phornpun Phokrai ◽

Somrudee Suwankulanan ◽

Narinthorn Phakdeeto ◽

Pattamaphorn Phunsomboon ◽

...

Keyword(s):

Hepatocellular Carcinoma ◽

Plasma Membrane ◽

Fatty Acid ◽

Cancer Therapy ◽

Cell Apoptosis ◽

Hepg2 Cells ◽

Cytotoxic Effect ◽

De Novo ◽

De Novo Lipogenesis ◽

Citrate Transporter

Increased expression levels of both mitochondrial citrate transporter (CTP) and plasma membrane citrate transporter (PMCT) proteins have been found in various cancers. The transported citrates by these two transporter proteins provide acetyl-CoA precursors for the de novo lipogenesis (DNL) pathway to support a high rate of cancer cell viability and development. Inhibition of the DNL pathway promotes cancer cell apoptosis without apparent cytotoxic to normal cells, leading to the representation of selective and powerful targets for cancer therapy. The present study demonstrates that treatments with CTP inhibitor (CTPi), PMCT inhibitor (PMCTi), and the combination of CTPi and PMCTi resulted in decreased cell viability in two hepatocellular carcinoma cell lines (HepG2 and HuH-7). Treatment with citrate transporter inhibitors caused a greater cytotoxic effect in HepG2 cells than in HuH-7 cells. A lower concentration of combined CTPi and PMCTi promotes cytotoxic effect compared with either of a single compound. An increased cell apoptosis and an induced cell cycle arrest in both cell lines were reported after administration of the combined inhibitors. A combination treatment exhibits an enhanced apoptosis through decreased intracellular citrate levels, which consequently cause inhibition of fatty acid production in HepG2 cells. Apoptosis induction through the mitochondrial-dependent pathway was found as a consequence of suppressed carnitine palmitoyl transferase-1 (CPT-1) activity and enhanced ROS generation by combined CTPi and PMCTi treatment. We showed that accumulation of malonyl-CoA did not correlate with decreasing CPT-1 activity. The present study showed that elevated ROS levels served as an inhibition on Bcl-2 activity that is at least in part responsible for apoptosis. Moreover, inhibition of the citrate transporter is selectively cytotoxic to HepG2 cells but not in primary human hepatocytes, supporting citrate-mediating fatty acid synthesis as a promising cancer therapy.

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BNIP3 attenuates hepatocellular carcinoma by promoting lipid droplet turnover at the lysosome.

10.21203/rs.3.rs-947988/v1 ◽

2021 ◽

Author(s):

Damian Berardi ◽

Althea Bock-Hughes ◽

Lauren Drake ◽

Alexander Terry ◽

Grazyna Bozek ◽

...

Keyword(s):

Hepatocellular Carcinoma ◽

Cell Growth ◽

Tumor Cell ◽

Lipid Droplet ◽

Lipid Accumulation ◽

De Novo ◽

De Novo Lipogenesis ◽

Acid Oxidation ◽

Tumor Cell Growth ◽

Lipid Levels

Abstract Hepatic steatosis is a major etiological factor in hepatocellular carcinoma (HCC). Work reported here identifies BNIP3 as a suppressor of HCC that mitigates against lipid accumulation. Loss of BNIP3 decreased tumor latency and increased tumor burden in a mouse model of HCC. This was associated with increased lipid accumulation and elevated HCC tumor cell growth. Conversely, exogenous BNIP3 decreased lipid levels and reduced HCC tumor cell growth. Mutant BNIP3W18A that is unable to promote mitophagy did not decrease HCC cell growth and was defective at reducing lipid levels. Growth suppression by BNIP3 was not mediated by effects on fatty acid oxidation (FAO) or de novo lipogenesis (DNL). Rather, BNIP3 suppressed HCC cell growth by promoting lipid droplet turnover at the lysosome through a process we have termed “mitolipophagy” in which lipid droplets and mitochondria are turned over together at the lysosome. Low BNIP3 expression in human HCC also correlated with increased lipid content and worse prognosis than HCC expressing high levels of BNIP3. This work reveals a role for BNIP3 and lipid droplet turnover at the lysosome in attenuating HCC.

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