Correction to "Genome-wide CRISPR-Cas9 screening identifies that hypoxia-inducible factor-1a-induced CBX8 transcription promotes pancreatic cancer progression via IRS1/AKT axis".

[This corrects the article on p. 1709 in vol. 13, PMID: 34853645.].

Genome-wide CRISPR-Cas9 screening identifies that hypoxia-inducible factor-1a-induced CBX8 transcription promotes pancreatic cancer progression via IRS1/AKT axis.

BACKGROUND: Pancreatic cancer (PC) is one of the most lethal malignancies worldwide. It is known that the proliferation of PC cells is a critical process in the disease. Previous studies have failed to identify the key genes associated with PC cell proliferation, using bioinformatic analysis, genome-wide association studies, and candidate gene testing. AIM: To investigate the function of the chromobox 8 (CBX8)/receptor substrate 1 (IRS1)/AKT axis in PC. METHODS: A genome-wide CRISPR-Cas9 screening was performed to select genes that could facilitate PC cell proliferation. Quantitative reverse transcription-polymerase chain reaction was used to detect the expression of CBX8 in PC tissues and cells. The regulatory roles of CBX8 in cell proliferation, migration, and invasion were verified by in vivo and in vitro functional assays. RESULTS: CBX8 was upregulated in PC tissues and shown to drive PC cell proliferation. Higher expression of CBX8 was correlated with worse outcomes of PC patients from two independent cohorts comprising a total of 116 cases. CBX8 was also proved to serve as a promising therapeutic target for a PC xenograft model. We demonstrated that hypoxia-inducible factor (HIF)-1a induced CBX8 transcription by binding to the promoter of CBX8. CBX8 efficiently activated the PI3K/AKT signaling by upregulating insulin IRS1. CONCLUSION: CBX8 is a key gene regulated by HIF-1α, and activates the IRS1/AKT pathway, which suggests that targeting CBX8 may be a promising therapeutic strategy for PC.

MEF2A-mediated lncRNA HCP5 Inhibits Gastric Cancer Progression via MiR-106b-5p/p21 Axis.

Background: Long non-coding RNAs (lncRNAs) are deemed to be relevant to the tumorigenesis and development of a variety of tumors, containing gastric cancer (GC). The purpose of our investigations is to explore the character of HCP5 in GC. Methods: HCP5 expression was detected by quantitative real-time polymerase chain reaction (qRT-PCR) in 62 matched GC tissues and corresponding para-carcinoma tissues. In vitro and in vivo functional assays were subjected to verify the biological effects of HCP5 after alteration of HCP5. Chromatin immunoprecipitation assay (CHIP) assays were conducted to confirm that myocyte enhancer factor 2A (MEF2A) could bind to HCP5 promoter regions and thereby induce HCP5 expression. Analysis of the latent binding of miR-106b-5p to HCP5 and p21 was made by bioinformatics prediction and luciferase reporter assays. Results: Significant downregulation of HCP5 was detected in GC tissues. Negative correlation was determined between HCP5 expression level and tumor size and overall survival in GC patients. HCP5 depletion had a facilitating impact on proliferation, migration and invasion of GC cells. Consistently, overexpression of HCP5 came into an opposite effect. Moreover, we demonstrated that MEF2A could combine with the promoter region of HCP5 and thereby induce HCP5 transcription. Luciferase reporter assays revealed that HCP5 could compete with miR-106b-5p as a competing endogenous RNA (ceRNA) and upregulated p21 expression in GC. Conclusions: MEF2A-mediated HCP5 could exert an anti-tumor effect among the development of GC via miR-106b-5p/p21 axis, which provides a novel target for GC therapy.

Abnormal expression of lncRNA UCA1 disturbed cell apoptosis through mediating mitochondrial dynamics in PDAC.

A great number of studies have shown the pivotal role of mitochondria in cancer progression and numerous studies indicated that lncRNAs are involved in tumor metabolism. However, the relationship between UCA1 and mitochondria in PDAC remains unclear. Here, we reported for the first time that UCA1-driven change in mitochondrial dynamics induced mitochondrial apoptotic pathway in PDAC. In this research, data mining revealed that upregulated UCA1 occurred in PDAC patients, which meant a high likelihood of a poor prognosis. Following, UCA1 silencing could notably decrease cell viability and induce cell apoptosis. Further research revealed that UCA1 silencing could induce more cytochrome c localization in the cytosol, which triggered the mitochondrial apoptotic pathway in PDAC cell lines. Meanwhile, the morphological analysis showed significantly enhanced mitochondrial fragmentation presented in UCA1 knockdown cells, coupled with increased expression of Drp1 and Fis1, together with an activation form of Drp1, which would promote mitochondria fission. Additional, mitochondrial fission inhibitor Mdivi1 markedly reversed the effects of the UCA1 knockdown on cell apoptosis in PDAC. Collectively, we deduce that UCA1-driven change in mitochondrial dynamics induced the mitochondrial apoptotic pathway in PDAC. Therefore, lncRNA UCA1 could be considered as a promising therapeutic target for the poor prognosis in PDAC.

M2 Macrophage-Derived Exosomes Promote Angiogenesis and Growth of Pancreatic Ductal Adenocarcinoma by Targeting E2F2.

Pancreatic ductal adenocarcinoma (PDAC), one of the most aggressive tumors all over the world, has a generally poor prognosis, and its progression is positively correlated with the density of blood vessels. Recently, tumor-associated macrophages (TAMs) were proven to be beneficial for angiogenesis, but their mechanism of action remains unclear. Our study indicated that M2 macrophages were positively correlated with the microvessel density (MVD) of PDAC tissues, and M2 macrophage-derived exosomes (MDEs) could promote the angiogenesis of mouse aortic endothelial cells (MAECs) in vitro. At the same time, the M2 MDEs could also promote the growth of subcutaneous tumors and increase the vascular density of mice. Moreover, we also found that miR-155-5p and miR-221-5p levels in the M2 MDEs were higher than those in M0 MDEs, and they could be transferred into MAECs, as demonstrated by RNA sequencing (RNA-seq) and qPCR analysis. Our data confirmed the interaction between TAMs and the angiogenesis of PDAC by exosomes. Additionally, targeting the exosomal miRNAs derived from TAMs might provide diagnostic and therapeutic strategies for PDAC.

Hypoxic Tumor-Derived Exosomal Long Noncoding RNA UCA1 Promotes Angiogenesis via miR-96-5p/AMOTL2 in Pancreatic Cancer.

The hypoxic microenvironment, an important feature of solid tumors, promotes tumor cells to release exosomes and enhances tumor angiogenesis. However, the detailed functions of hypoxic exosomes and the mechanisms underlying their effects in pancreatic cancer (PC) remain mysterious. Here, we observed that hypoxic exosomes derived from PC cells promoted cell migration and tube formation of human umbilical vein endothelial cells (HUVECs). The long noncoding RNA (lncRNA) UCA1, a key factor, was highly expressed in exosomes derived from hypoxic PC cells and could be transferred to HUVECs through the exosomes. In addition, the expression levels of UCA1 in exosomes derived from PC patients' serum were higher than in healthy controls and were associated with poor survival of PC patients. Moreover, hypoxic exosomal UCA1 could promote angiogenesis and tumor growth both in vitro and in vivo. With respect to the functional mechanism, UCA1 acted as a sponge of microRNA (miR)-96-5p, relieving the repressive effects of miR-96-5p on the expression of its target gene AMOTL2. Collectively, these results indicate that hypoxic exosomal UCA1 could promote angiogenesis and tumor growth through the miR-96-5p/AMOTL2/ERK1/2 axis and therefore, serve as a novel target for PC treatment.

Dermatosis as the initial presentation of gastric cancer: two cases.

Paraneoplastic dermatoses are known to be certain dermatosis related with tumor. The common paraneoplastic dermatoses are acanthosis nigricans, acquired ichthyosis, dermatomyositis, erythroderma, and so on. Here we report two cases of paraneoplastic dermatoses associated with gastric cancer. One case was a 57-year-old man with dermatomyositis and proved to be associated with gastric cancer through stomachoscopy. The other was a 66-year-old man with erythroderma and proved to be associated with gastric cancer through stomachoscopy. Both cases were treated with radical total gastrectomy with lymphadenectomy (D2) and esophagojejunostomy of Roux-en-Y. The skin symptom of both cases had improved a lot but still existed after operation. Paraneoplastic dermatoses can be seen as the early manifestation of visceral carcinomas. As a result, gastric cancers should be excluded in the patients with paraneoplastic dermatoses.