Metastatic colorectal cancer (mCRC) patients have poor overall survival despite using irinotecan- or oxaliplatin-based chemotherapy combined with anti-EGFR (epidermal growth factor receptor) drugs, especially those with the oncogene mutation ofKRAS. Metformin has been reported as a potentially novel antitumor agent in many experiments, but its therapeutic activity is discrepant and controversial so far. Inspiringly, the median survival time forKRAS-mutation mCRC patients with diabetes on metformin is 37.8 mo longer than those treated with other hypoglycemic drugs in combination with standard systemic therapy. In contrast, metformin could not improve the survival of mCRC patients with wild-typeKRAS. Interestingly, metformin is preferentially accumulated inKRAS-mutation mCRC cells, but not wild-type ones, in both primary cell cultures and patient-derived xenografts, which is in agreement with its tremendous effect inKRAS-mutation mCRC. Mechanistically, the mutated KRAS oncoprotein hypermethylates and silences the expression of multidrug and toxic compound extrusion 1 (MATE1), a specific pump that expels metformin from the tumor cells by up-regulating DNA methyltransferase 1 (DNMT1). Our findings provide evidence thatKRAS-mutation mCRC patients benefit from metformin treatment and targeting MATE1 may provide a strategy to improve the anticancer response of metformin.

Gastric cancer is one of the most malignant tumor types, and its metastasis is a notable cause of mortality. Among the methods of tumor metastasis, lymphatic metastasis is the predominant one in gastric cancer. A previous study reported that the plasma oxidized low-density lipoprotein (oxLDL) is the risk factor associated with the development of tumors in patients with abnormal lipid metabolism, but the influence of plasma oxLDL in the lymphatic metastasis of gastric cancer remains unclear. In the present study, the concentration of plasma oxLDL from patients with gastric cancer was detected with an ELISA kit, and the lymphatic vessel density in gastric cancer tissues was determined by D2-40 staining. The correlation analysis of oxLDL concentration and lymphatic vessel density demonstrated that plasma oxLDL was positively correlated with lymphatic metastasis in patients with gastric cancer. Subsequently, the popliteal lymph node metastasis animal experiment with nude mice confirmed that oxLDL could promote the lymphatic metastasis of gastric cancer. Following this, the western blotting and ELISA data demonstrated that oxLDL promoted the expression and secretion of vascular endothelia growth factor (VEGF)-C in gastric cancer cell lines. Finally, blocking the lectin-like oxLDL-1 (LOX-1) receptor, a specific receptor for oxLDL, and the nuclear factor (NF)-κB signaling pathway following oxLDL (50 µg/ml) treatment in HGC-27 cells revealed that oxLDL could activate the NF-κB signaling pathway mediated by LOX-1, with subsequent upregulation of VEGF-C expression, and secretion in and from gastric cancer cells, and finally that it could promote the lymphatic metastasis of gastric cancer. These data indicate the association between the plasma oxLDL and the lymphatic metastasis of gastric cancer, and indicate that oxLDL elimination may be a potential therapeutic target for the prevention and intervention of early lymph node metastasis in gastric cancer.

These findings demonstrated that kallistatin functions as an endogenous lymphangiogenesis inhibitor and has an important part in the lymphatic metastasis of gastric cancer.

Abnormal lipid metabolism is the sign of tumour cells. Previous researches have revealed that the lipolytic pathway may contribute to the progression of colorectal cancer (CRC). However, adipose triglyceride lipase (ATGL) role in CRC cells remains unclear. Here, we find that elevated ATGL positively correlates with CRC clinical stages and negatively associates with overall survival. Overexpression of ATGL significantly promotes CRC cell proliferation, while knockdown of ATGL inhibits the proliferation and promotes the apoptosis of CRC cells in vitro. Moreover, in vivo experiments, ATGL promotes the growth of CRC cells. Mechanistically, ATGL enhances the carcinogenic function of CRC cells via promoting sphingolipid metabolism and CoA biosynthesis pathway‐related gene levels by degrading triglycerides, which provides adequate nutrition for the progression of CRC. Our researches clarify for the first time that ATGL is a novel oncogene in CRC and may provide an important prognostic factor and therapeutic target for CRC.

Current non-invasive tumor biomarkers failed to accurately identify patients with colorectal cancer (CRC), delaying CRC diagnosis and thus leading to poor prognosis. Dysregulation of 5-Methylcytosine (m5C) RNA has gradually been reported in various cancers, but their role in tumor diagnosis is rarely mentioned. Our study aimed to determine the role of m5C methylation modification in blood immune cells for the diagnosis of CRC. Peripheral blood samples were obtained from a total of 83 healthy controls and 196 CRC patients. We observed that m5C RNA contents in blood immune cells of CRC patients were markedly enhanced in both training set and validation set. Moreover, levels of m5C increased with CRC progression and metastasis but reduced after treatment. Compared with common blood tumor biomarkers, m5C levels in peripheral blood immune cells had superior discrimination and reclassification performance in diagnosing CRC. Besides, bioinformatics and qRT-PCR analysis identified increased expression of m5C-modified regulators NSUN5 and YBX1 in CRC patients’ blood. A series of animal models and cell co-culture models further demonstrated that CRC tumor cells could increase immune cells’ m5C levels and m5C-modified regulators. Monocyte was the predominant m5C-modified immune cell type in CRC patients’ blood by Gene set variation analysis (GSVA). Taken together, m5C methylation modification in peripheral blood immune cells was a promising biomarker for non-invasive diagnosis of CRC.