LncRNA POT1-AS1 accelerates the progression of gastric cancer by serving as a competing endogenous RNA of microRNA-497-5p to increase PDK3 expression

Transcriptome of Lung Cancer Cells Resistant to the Cytotoxic Activity of Macrophages

The role of the immune system in tumor progression has been the subject of research for more than 100 years since Paul Ehrlich hypothesized that the presence of the immune system limits the occurrence of cancer. One of the mechanisms hindering the initiation and progression of the tumor is the cytotoxic activity of macrophages; however, in some cases, it is not sufficient to control tumorigenesis. This may be due to both the development of resistance of tumor cells to the antitumor activity of macrophages and the development of a tolerant phenotype of macrophages that do not have sufficient antitumor activity. In this work, the lung cancer cells resistant to the cytotoxic action of macrophages were obtained and characterized for the first time, and the genes associated with the observed changes were identified. Understanding the mechanisms of resistance of tumor cells to the cytotoxic activity of macrophages and the peculiarities of its manifestation in a tumor environment is critically important for improving the effectiveness of the existing methods of cancer treatment and developing novel methods for tumor immunotherapy.

Identification of a Hypoxia-Angiogenesis lncRNA Signature Participating in Immunosuppression in Gastric Cancer

Hypoxia and angiogenesis are the leading causes of tumor progression, and their strong correlation has been discovered in many cancers. However, their collective function’s prognostic and biological roles were not reported in gastric cancer. Hence, we aimed to investigate the effects of hypoxia and angiogenesis on gastric cancer via sequencing data. This study used weighted gene coexpression network analysis and random forest regression to build a hypoxia-angiogenesis-related model (HARM) via the TCGA-STAD lncRNA data. It estimated the HARM’s correlation with clinical features and its accuracy for survival prediction. Sequential functional analyses were conducted to investigate its biological role, and we next sought the immune landscape status and immunological function variation by ESTIMATE score calculation and GSVA, respectively. Seven different algorithms were conducted to assess the immunocyte infiltration, and TIDE score and immune checkpoint levels were compared between the high- and low-HARM groups. As a result, we found that HARM predicted patient survival with high accuracy and was correlated with higher stages of gastric cancer. Various cancer-associated pathways and macrophage-related regulations were upregulated in the high-HRAM group. The high-HARM group harbored higher immune levels, and M2 macrophages and cancer-associated fibroblasts were particularly highly unfiltered. Furthermore, globally upregulated immune checkpoints and higher TIDE scores were observed in the high-HARM group. Finally, we filtered eight drugs with lower IC50 in the high-HARM group as potential drugs for the HARM-targeted therapy. We believe this study opens up novel perspectives into the interaction between hypoxia-angiogenesis and immunosuppression and will provide novel insights for gastric cancer immunotherapy.

Clinical significance and correlation of miR-200c and P-gp expression in gastric cancer and the effects on multidrug resistance

BACKGROUND

Poor prognosis is common in gastric cancer patients due to multidrug resistance (MDR)-induced recurrence and metastasis. In the present study, we investigated the expression of microRNA (miR)-200c in gastric cancer tissues and cell lines and its relationship with the expression of the drug resistant gene ABCB1, which encodes P-glycoprotein (P-gp).

METHODS

The basic characteristics of 102 patients with gastric cancer were reviewed. Real time-polymerase chain reaction (PCR), immunohistochemistry, and Western blot were employed to detect the expression levels of miR-200c and P-gp in gastric carcinoma tissues and cell lines. The correlation of miR-200c messenger RNA (mRNA) level with clinicopathological characteristics and P-gp protein expression were analyzed. SGC7901/vincristine (VCR) cells were transfected with miR-200c mimics or a specific small interfering RNA (siRNA) targeting the ABCB1 gene. The methyl thiazolyl tetrazolium (MTT) assay and flow cytometry were used to determine the role of miR-200c and ABCB1 on the viability and apoptosis of gastric carcinoma cell lines.

RESULTS

The level of miR-200c in carcinoma tissues was significantly lower than that in adjacent tissues, and the expression level of P-gp in carcinoma tissues was obviously higher than that in adjacent tissues (P<0.01, P=0.029). The expression levels of miR-200c and P-gp were associated with the malignant characteristics of gastric cancer, and patients with high expression of miR-200c or negative expression of P-gp had a better prognosis (P=0.006, P=0.022). MiR-200c negatively regulated the ABCB1 gene in gastric cancer cell lines. MiR-200c overexpression and ABCB1 down-regulation increased the sensitivity of SGC7901/VCR cells to VCR and reversed MDR by promoting cell apoptosis.

CONCLUSIONS

The expression level of miR-200c decreases in gastric carcinoma tissues and drug-resistant gastric cancer SGC7901/VCR cells. Overexpression of miR-200c may enhance the sensitivity of SGC7901/VCR cells to VCR by regulating the expression of P-gp.