2019年 · 第02卷第01期

Programmed death ligand-1 (PD-L1) is involved in inhibiting of T lymphocyte proliferation, producing cytokine, cytolytic activity, and suppressing of the immune response. Genes with molecular alterations involved in DNA mismatch repair promote cancer initiation and tumor progression. Clinical studies show that colorectal cancer (CRC) patients harboring microsatellite instability (MSI) have a higher anti-programmed cell death protein 1/PD-L1 immunotherapy response ratio compared with microsatellite stable subgroup patients. The underlying mechanism has however remained unclear. Here, we found that compared with microsatellite stable samples, PD-L1 was glycosylated and highly expressed both in MSI CRC cell lines and tissue samples. Specifically, PD-L1 was N-glycosylated at its N35, N192, N200, and N219 sites, and the four glycosylation sites were all responsible for PD-L1 degradation. Additionally, non-glycosylated PD-L1 underwent rapid degradation compared with glycosylated PD-L1 through the 26S proteasome pathway. The faster degradation of the non-glycosylated PD-L1 was ascribed to its binding to glycogen synthase kinase 3β via ubiquitination. This degradation phenotype was, however, not observed for glycosylated PD-L1. Significantly, glycosylated PD-L1 was up-regulated by activated epidermal growth factor receptor in MSI CRC cells. Together, our results indicate that epidermal growth factor receptor stabilized PD-L1 via glycosylation in MSI CRC cells, uncovering a novel role of PD-L1 in MSI CRC immunosuppression and disease progression. The study was approved by the Clinical Ethics Review Committee at the Six Affiliated Hospital of Sun Yat-sen University, China (Approval No. 2019ZSLYEC-005).

The genetic basis underlying liver fibrosis remains largely unknown. We conducted a study to identify genetic alleles and underlying pathways associated with hepatic fibrogenesis and fibrosis at the genome-wide level in 121 human livers. By accepting a liberal significance level of P < 1e-4, we identified 73 and 71 candidate loci respectively affecting the variability in alpha-smooth muscle actin (α-SMA) levels (fibrogenesis) and total collagen content (fibrosis). The top genetic loci associated with the two markers were BAZA1 and NOL10 for α-SMA expression and FAM46A for total collagen content (P < 1e-6). We further investigated the relationship between the candidate loci and the nearby gene transcription levels (cis-expression quantitative trait loci) in the same liver samples. We found that 44 candidate loci for α-SMA expression and 44 for total collagen content were also associated with the transcription of the nearby genes (P < 0.05). Pathway analyses of these genes indicated that macrophage migration inhibitory factor (MIF) related pathway is significantly associated with fibrogenesis and fibrosis, though different genes were enriched for each marker. The association between the single nucleotide polymorphisms, MIF and α-SMA showed that decreased MIF expression is correlated with increased α-SMA expression, suggesting that variations in MIF locus might affect the susceptibility of fibrogenesis through controlling MIF gene expression. In summary, our study identified candidate alleles and pathways underlying both fibrogenesis and fibrosis in human livers. Our bioinformatics analyses suggested MIF pathway as a strong candidate involved in liver fibrosis, thus further investigation for the role of the MIF pathway in liver fibrosis is warranted. The study was reviewed and approved by the Institutional Review Board (IRB) of Wayne State University (approval No. 201842) on May 17, 2018.

Whether regional lymph node involvement exerts significant effect on the prognosis still remains obscure for pancreatic neuroendocrine tumors. To clarify this association and identify predictors for lymph node involvement, we studied the data of patients aged >18 years with regional lymph node involvement histologically confirmed pancreatic neuroendocrine tumors from 2004 to 2014 in the Surveillance, Epidemiology, and End Results database (http://seer.cancer.gov/about). We evaluated Lymph node involvement as a prognostic factor by Cox regression. We reduced 9 variables of demographic and tumor characteristics to 5 potential predictors using least absolute shrinkage and selection operator (LASSO) regression model. We further constructed a lymph node involvement model by logistic regression. The model was verified by the verification set, and the visual expression of the model was realized by a nomogram. A total of 1545 cases of pancreatic neuroendocrine tumors were included in our study. Lymph node positivity was significantly associated with disease-specific survival (P < 0.001). Younger patients (P < 0.05), patients with tumors in the pancreatic head (P < 0.05), patients at high American Joint Committee on Cancer T stage (P < 0.001), and patients of an undifferentiated status (P < 0.05) showed a significantly higher possibility of developing lymph node involvement. The reliability of this model was verified by cross-validation between the training and testing set, and we obtained good discrimination and calibration power. This model also showed great performance in C-index and area under receiver operating characteristic curve. Lymph node positivity was an important negative prognostic predictor for pancreatic neuroendocrine tumor. We developed a lymph node involvement model based on the predictors including age, marital status, primary site, T status, and tumor grade.

Breast cancer is one of the most common malignant tumors in women all over the world. Metastasis represents a major adverse progression of breast cancer, resulting in poor survival duration. Axillary lymph node metastasis is often the first step of systemic metastasis process of breast cancer. However, the mechanism of lymph node metastasis and the genomic signatures of primary breast tumors and lymph node metastasis are still under exploration. Whole exome sequencing was applied to primary breast cancer, axillary metastatic lymph nodes, and white blood cells from 10 Chinese women patients in our study. Single nucleotide variants (SNVs) and copy-number variants (CNVs) were compared between primary tumors and lymph nodes for individual patients. There are somatic SNVs (average 5.58 ± 2.56 per megabase) in primary breast cancers and somatic SNVs (average 5.46 ± 2.66 per megabase) in axillary metastatic lymph nodes were identified, which is corresponding to a semblable mutation burden in two malignant sites (P= 0.81). No difference was found in CNVs (P = 0.33). In primary breast cancer, somatic SNVs (48.12 ± 13.80%) and CNVs (61.72 ± 35.00%) were overlapping with somatic SNVs (49.43 ± 12.30%) and CNVs (72.01 ± 24.31%) in axillary metastatic lymph nodes. Nine genes were screened for significant specific mutations in primary tumors, and 15 genes were significantly mutated in metastatic lymph nodes. Using MutSigCV screening, it was found that HRNR and AHNAK2 are lymph node metastasis-specific genes. In our study, primary breast tumors are directly related to axillary lymph node metastases together and there are most SNVs and CNVs which were overlapping in primary and metastatic sites. These variants which are overlapping is closely related to the metastatic process of tumor invasion with early genetic variability. This is the first time to prove the concept of polyclonal metastatic model and in this model more than one clone migrates establish the metastases to axillary lymph nodes. This study was approved by the institutional review board (IRB) of the Cancer Hospital, Chinese Academy of Medical Sciences, and Peking Union Medical College, China (approval No. NCC2016G-030) on March 3, 2016.

Traditional methods of inducing hyperlipidemia in animal models are either costly (genetic manipulation) or it is difficult to control for the effects of other variables. For example, during high-fat feeding, the amount of high-fat diet intake per animal cannot be precisely controlled. The aim of this study was to develop an experimental model of fatty organ degeneration induced by poloxamer 407 (P-407). The study was conducted in 2-month-old, male Sprague-Dawley rats that were administered intraperitoneally with either 10% (w/w) P-407 (1 g/kg) or saline (10 mL/kg) for 4 months. Their lipid profile, organ degeneration due to fat deposition, and body mass were assessed. Intraperitoneal administration of P-407 resulted in significant increases in plasma triglycerides (P ≤ 0.001), total cholesterol (P < 0.001), high-density lipoprotein-cholesterol (P ≤ 0.001), and low-density lipoprotein (P < 0.001) cholesterol. In contrast to the control group, fatty tissue degeneration was observed in the liver, spleen, and kidneys of P-407-treated rats. Positive correlations between fatty tissue degeneration, and the atherogenic index of plasma (P < 0.001) and the ratio of total cholesterol to high-density-lipoprotein (P < 0.001) were identified. In addition, treatment with P-407 for 3 to 4 months caused a significant reduction in body mass relative to controls (P < 0.001). Thus, this study describes the development of a cost-effective experimental rat model of organ degeneration, characterized by fat accumulation in the liver, spleen, and kidneys, which could be used for the study of steatosis and related diseases arising from sustained untreated dyslipidemia. Furthermore, both the atherogenic index of plasma and the ratio of total cholesterol to high-density lipoprotein-cholesterol can be used to predict the risk of fatty tissue degeneration in this model. The study was approval of the University of Jishou Biomedical Research Ethics Committee, China.

Promoting intestinal epithelial regeneration remains a major medical challenge. Female patients taking nonsteroidal anti-inflammatory drugs are less likely to have upper gastrointestinal bleeding and ulcers than males. Using a nonsteroidal anti-inflammatory drug-induced intestinal damage mouse model, we verified that female mice recover faster than males following acute intestinal insult. Using ex vivo intestinal organoid cultures, we showed that estrogen is necessary and sufficient in enhancing the female organoid formation from breached isolated crypts via the estrogen receptor β receptor. Thus, estrogen promotes female intestinal epithelial organoid regeneration to lower the incidence of intestinal bleeding and ulceration. Animal studies were approved by University of Utah IACUC under protocol number 16-05012 and 18-02010.

Autoimmune liver disease, including autoimmune hepatitis, primary biliary cholangitis, and primary sclerosing cholangitis, is a chronic autoimmune liver condition characterized by abnormal accumulation of proinflammatory immune cells. As more and more genetic studies are conducted, it is becoming increasingly clear that genetic risk cannot fully explain disease pathogenesis. Epigenetic modifications, including CpG island DNA methylation, histone modification, and microRNA-mediated gene silencing, are gradually being acknowledged to play a role in immune cellular identity and disease heterogeneity. Given the heterogeneity and environmental exposure bias observed in patients, it is essential to uncover the epigenetic mechanisms of autoimmune liver disease, which could integrate environmental skewing, cell lineage commitment, and genetics to provide a fuller mechanistic understanding of the disease. Epigenetic profiling holds promise for identifying diagnostic and prognostic biomarkers, and epigenetic manipulations could result in novel therapies. Cutting-edge breakthroughs are frequently being made in epigenetics, which might guide future explorations into autoimmune liver disease.