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Abnormal lipid metabolism has been commonly observed in various human cancers, including colorectal cancer (CRC). The mitochondrial citrate carrier SLC25A1 (also known as mitochondrial citrate/isocitrate carrier, CIC), has been shown to play an important role in lipid metabolism regulation. Our bioinformatics analysis indicated that SLC25A1 was markedly upregulated in CRC. However, the role of SLC25A1 in the pathogenesis and aberrant lipid metabolism in CRC remain unexplored. Here, we found that SLC25A1 expression was significantly increased in tumor samples of CRC as compared with paired normal samples, which is associated with poor survival in patients with CRC. Knockdown of SLC25A1 significantly inhibited the growth of CRC cells by suppressing the progression of the G1/S cell cycle and inducing cell apoptosis both in vitro and in vivo, whereas SLC25A1 overexpression suppressed the malignant phenotype. Additionally, we demonstrated that SLC25A1 reprogrammed energy metabolism to promote CRC progression through two mechanisms. Under normal conditions, SLC25A1 increased de novo lipid synthesis to promote CRC growth. During metabolic stress, SLC25A1 increased oxidative phosphorylation (OXPHOS) to protect protects CRC cells from energy stress-induced cell apoptosis. Collectively, SLC25A1 plays a pivotal role in the promotion of CRC growth and survival by reprogramming energy metabolism. It could be exploited as a novel diagnostic marker and therapeutic target in CRC.

Background: Protease serine 8 (PRSS8), a trypsin-like serine peptidase, has been shown to function as a tumour suppressor in various malignancies. The present study aimed to investigate the expression pattern, prognostic value and the biological role of PRSS8 in human hepatocellular carcinoma (HCC). Methods: PRSS8 expression in 106 HCC surgical specimens was examined by Real-time polymerase chain reaction (PCR) and immunohistochemistry, and its clinical significance was analysed. The role of PRSS8 in cell proliferation, apoptosis and invasion were examined in vitro and in vivo. Results: PRSS8 mRNA and protein expression were decreased in most HCC tumours from that in matched adjacent non-tumour tissues. Low intratumoral PRSS8 expression was significantly correlated with poor overall survival (OS) in patients with HCC (P = 0.001). PRSS8 expression was an independent prognostic factor for OS (hazard ratio [HR] = 1.704, P = 0.009). Furthermore, restoring PRSS8 expression in high metastatic HCCLM3 cells significantly inhibited cell proliferation and invasion. In contrast, silencing PRSS8 expression in non-metastatic HepG2 cells significantly enhanced cell growth and invasion. Moreover, our in vivo data revealed that attenuated PRSS8 expression in HepG2 cells greatly promoted tumour growth, while overexpression of PRSS8 remarkably inhibited tumour growth in an HCCLM3 xenograft model. Enhanced cell growth and invasion ability mediated by the loss of PRSS8 expression was associated with downregulation of PTEN, Bax and E-cadherin and an upregulation in Bcl-2, MMP9 and N-cadherin. Conclusions: Our data demonstrate that PRSS8 may serve as a tumour suppressor in HCC progression, and represent a valuable prognostic marker and potential therapeutic target for HCC.

PurposeColorectal carcinoma (CRC) is among the most common causes of death. Recent studies have shown that both STAT3 and miR-572 contribute to CRC progression. STAT3 plays an important role in miRNA expression. Moreover, MOAP-1, which is a pro-apoptotic protein that induces cell death or apoptosis, has a direct correlation with miRNA. Therefore, the current study is designed to explore whether miR-572 and STAT3 are involved in a common pathway and the role of MOAP-1 in this process.Patients and methodsThe expressions of STAT3, miR-572, and MOAP-1 in human CRC tissues and multiple cell lines were estimated by qRT-PCR or Western blot. MTT, transwell migration, and invasion assays were used to assess cell growth, migration, and invasion, respectively. Dual-luciferase reporter assay was applied to examine the association between miR-572 and MOAP-1.ResultsElevated STAT3 levels were accompanied by increased miR-572 and decreased MOAP-1 levels in primary CRC specimens and cell lines. STAT3 promoted CRC cell growth, migration, and invasion via the upregulated expression of miR-572. Subsequently, miR-572 inhibited MOAP-1 protein expression through an interaction with its 3′UTR.ConclusionOur study proposes a novel STAT3-miR-572-MOAP-1 pathway involved in the process of CRC progression, which might be a potential target for the development of new preventive and therapeutic approaches against human colorectal cancer.