LINC00239 Interacts with C-Myc Promoter-Binding Protein-1 (MBP-1) to Promote Expression of C-Myc in Esophageal Squamous Cell Carcinoma

Marine natural product lepadin A as a novel inducer of immunogenic cell death via CD91-dependent pathway

Immunogenic Cell Death (ICD) represents a mechanism of enhancing T cell-driven response against tumor cells. The process is enabled by release of damage-associated molecular patterns (DAMPs) and cytokines by dying cells. Based on molecular studies and clinical marker assessment, ICD can be a new target for cancer chemotherapy hitherto restricted to a few conventional anticancer drugs. In view of the development of small molecules in targeted cancer therapy, we reported the preliminary evidence on the role of the natural product lepadin A (1) as a novel ICD inducer. Here we describe the ICD mechanism of lepadin A (1) by proving the translocation of the protein calreticulin (CRT) to the plasma membrane of human A2058 melanoma cells. CRT exposure is an ICD marker in clinical studies and was associated with the activation of the intrinsic apoptotic pathway in A2058 cells with lepadin A (1). After the treatment, the tumour cells acquired the ability to activate dendritic cells (DCs) with cytokine release and costimulatory molecule expression that is consistent with a phenotypic profile committed to priming T lymphocytes via a CD91-dependent mechanism. The effect of lepadin A (1) was dose-dependent and comparable to the response of the chemotherapy drug doxorubicin (2), a well-established ICD inducer.

Tumor cell-derived exosomal lncRNA LOC441178 inhibits the tumorigenesis of esophageal carcinoma through suppressing macrophage M2 polarization

Esophageal carcinoma (EC) is a highly malignant type of tumor. In a previous study, the authors found that long non-coding RNA (lncRNA) LOC441178 inhibited the tumorigenesis of EC. Moreover, exosomes derived from tumor cells containing lncRNAs were found to play a key role in the tumor environment; however, whether exosomes can affect the tumor microenvironment by carrying LOC441178 remains unclear. Thus, the present study aimed to clarify this. In order to assess the effects of exosomal LOC441178 in EC, cell invasion and migration were examined using the Transwell assay. Exosomes were identified using transmission electron microscopy, Western blot analysis and nanoparticle tracking analysis. Furthermore, macrophage surface makers (CD206 and CD86) were analyzed using flow cytometry. Moreover, a subcutaneous xenograft mouse model was constructed to assess the role of TE-9 cells-derived exosomal LOC441178 in EC. The results revealed that LOC441178 overexpression notably suppressed the metastasis of EC cells. In addition, exosomes were successfully isolated from EC cells, and LOC441178 level was upregulated in exosomes derived from LOC441178- overexpressed EC cells. Exosomal LOC441178 also suppressed macrophage M2 polarization, and the polarized macrophages decreased EC cell invasion. Exosomes containing LOC441178 notably inhibited the growth of EC in mice. On the whole, the present study demonstrated that the delivery of LOC441178 by EC cell-secreted exosomes inhibited the tumorigenesis of EC by suppressing the polarization of M2 macrophages. These findings may provide a new theoretical basis for discovering new strategies against EC.

LncRNA RPL34-AS1 suppresses the proliferation, migration and invasion of esophageal squamous cell carcinoma via targeting miR-575/ACAA2 axis

BACKGROUND

Long noncoding RNAs (lncRNAs) are abnormally expressed in a broad type of cancers and play significant roles that regulate tumor development and metastasis. However, the pathological roles of lncRNAs in esophageal squamous cell carcinoma (ESCC) remain largely unknown. Here we aimed to investigate the role and regulatory mechanism of the novel lncRNA RPL34-AS1 in the development and progression of ESCC.

METHODS

The expression level of RPL34-AS1 in ESCC tissues and cell lines was determined by RT-qPCR. Functional experiments in vitro and in vivo were employed to explore the effects of RPL34-AS1 on tumor growth in ESCC cells. Mechanistically, fluorescence in situ hybridization (FISH), bioinformatics analyses, luciferase reporter assay, RNA immunoprecipitation (RIP) assay and western blot assays were used to detect the regulatory relationship between RPL34-AS1, miR-575 and ACAA2.

RESULTS

RPL34-AS1 was significantly down-regulated in ESCC tissues and cells, which was negatively correlated with overall survival in ESCC patients. Functionally, upregulation of RPL34-AS1 dramatically suppressed ESCC cell proliferation, colony formation, invasion and migration in vitro, whereas knockdown of RPL34-AS1 elicited the opposite function. Consistently, overexpression of RPL34-AS1 inhibited tumor growth in vivo. Mechanistically, RPL34-AS1 acted as a competing endogenous RNA (ceRNA) of miR-575 to relieve the repressive effect of miR-575 on its target ACAA2, then suppressed the tumorigenesis of ESCC.

CONCLUSIONS

Our results reveal a role for RPL34-AS1 in ESCC tumorigenesis and may provide a strategy for using RPL34-AS1 as a potential biomarker and an effect target for patients with ESCC.

Long noncoding RNA LINC00239 inhibits ferroptosis in colorectal cancer by binding to Keap1 to stabilize Nrf2

Ferroptosis, a novel regulated cell death induced by iron-dependent lipid peroxidation, plays an important role in tumor development and drug resistance. Long noncoding RNAs (lncRNAs) are associated with various types of cancer. However, the precise roles of many lncRNAs in tumorigenesis remain elusive. Here we explored the transcriptomic profiles of lncRNAs in primary CRC tissues and corresponding paired adjacent non-tumor tissues by RNA-seq and found that LINC00239 was significantly overexpressed in colorectal cancer tissues. Abnormally high expression of LINC00239 predicts poorer survival and prognosis in colorectal cancer patients. Concurrently, we elucidated the role of LINC00239 as a tumor-promoting factor in CRC through in vitro functional studies and in vivo tumor xenograft models. Importantly, overexpression of LINC00239 decreased the anti-tumor activity of erastin and RSL3 by inhibiting ferroptosis. Collectively, these data suggest that LINC00239 plays a novel and indispensable role in ferroptosis by nucleotides 1-315 of LINC00239 to interact with the Kelch domain (Nrf2-binding site) of Keap1, inhibiting Nrf2 ubiquitination and increasing Nrf2 protein stability. Considering the recurrence and chemoresistance constitute the leading cause of death in colorectal cancer (CRC), ferroptosis induction may be a promising therapeutic strategy for CRC patients with low LINC00239 expression.

A Pleiotropic Role of Long Non-Coding RNAs in the Modulation of Wnt/β-Catenin and PI3K/Akt/mTOR Signaling Pathways in Esophageal Squamous Cell Carcinoma: Implication in Chemotherapeutic Drug Response

Despite the availability of modern techniques for the treatment of esophageal squamous cell carcinoma (ESCC), tumor recurrence and metastasis are significant challenges in clinical management. Thus, ESCC possesses a poor prognosis and low five-year overall survival rate. Notably, the origin and recurrence of the cancer phenotype are under the control of complex cancer-related signaling pathways. In this review, we provide comprehensive knowledge about long non-coding RNAs (lncRNAs) related to Wnt/β-catenin and phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway in ESCC and its implications in hindering the efficacy of chemotherapeutic drugs. We observed that a pool of lncRNAs, such as HERES, TUG1, and UCA1, associated with ESCC, directly or indirectly targets various molecules of the Wnt/β-catenin pathway and facilitates the manifestation of multiple cancer phenotypes, including proliferation, metastasis, relapse, and resistance to anticancer treatment. Additionally, several lncRNAs, such as HCP5 and PTCSC1, modulate PI3K/Akt/mTOR pathways during the ESCC pathogenesis. Furthermore, a few lncRNAs, such as AFAP1-AS1 and LINC01014, block the efficiency of chemotherapeutic drugs, including cisplatin, 5-fluorouracil, paclitaxel, and gefitinib, used for ESCC treatment. Therefore, this review may help in designing a better therapeutic strategy for ESCC patients.

CREB3 Transactivates lncRNA ZFAS1 to Promote Papillary Thyroid Carcinoma Metastasis by Modulating miR-373-3p/MMP3 Regulatory Axis

The incidence rate of thyroid carcinoma ranks ninth among human malignancies, and it accounts for the most frequent malignancy in endocrine-related tumors. This study aimed to investigate the role of long noncoding RNA (lncRNA) ZFAS1 in the metastasis of papillary thyroid carcinoma (PTC) and the potential molecular mechanisms. Both ZFAS1 and MMP3 were highly expressed in thyroid carcinoma and PTC cell, as measured by the q-PCR and TCGA database. In addition, ZFAS1 induced TPC-1 metastasis through inducing the epithelial-mesenchymal transition (EMT) process. Besides, ZFAS1 knockdown by siRNA induced miR-373-3p expression and reduced MMP3 expression, as quantified by q-PCR and Western blotting. According to the luciferase assay, both ZFAS1 and MMP3 were classified as the direct targets of miR-373-3p. However, MMP3 itself did not affect ZFAS1. Using the online prediction tool, CREB3 was predicted as the transcription factor (TF) of ZFAS1 that contained two binding sites on its promoter region, and CREB3 was positively correlated with ZFAS1 in thyroid carcinoma cohorts. Results from the dual-luciferase assay and ChIP-qPCR indicated that both the two binding sites were essential for the transcription of ZFAS1. In conclusion, CREB3 activated lncRNA ZFAS1 at the transcriptional level to promote PTC metastasis by modulating miR-373-3p/MMP3.