LncGPR107 drives the self-renewal of liver tumor initiating cells and liver tumorigenesis through GPR107-dependent manner

lncRNA SNHG9 enhances liver cancer stem cell self-renewal and tumorigenicity by negatively regulating PTEN expression via recruiting EZH2

Liver cancer stem cell (CSC) self-renewal and tumorigenesis are important causes of hepatocellular carcinoma (HCC) recurrence. We purposed to investigate the function of long noncoding RNA small nucleolar RNA host gene 9 (SNHG9) in liver CSC self-renewal and tumorigenesis in this study. Flow cytometry was carried out to separate CD133+ Populations and CD133- Populations from HCC cell lines. A combination of CD133+ cells and Matrigel matrix was subcutaneously injected to create the NOD-SCID mouse xenograft tumor model. Colony formation test and spheroids formation assay were carried out to clarify the impact of SNHG9 on the self-renewal of liver CSCs. RNA immunoprecipitation, RNA-pull down, and chromatin immunoprecipitation were performed on CD133+ cells to elucidate the mechanism of SNHG9 regulating PTEN expression. We found that SNHG9 was highly expressed in HCC clinical samples, HCC cells, and CD133+ cells. In vitro, interference with SNHG9 prevented the formation of colonies and spheroids in liver CSC cells and primary HCC cells. In vivo, interference with SNHG9 reduced the tumor volume and weight. SNHG9 could bind to EZH2, and SNHG9 interference suppressed EZH2 recruitment and H3K27me3 levels in the PTEN promoter region. In addition, SNHG9 inhibition promoted PTEN expression while having little impact on EZH2 levels. Interference with SNHG9 inhibited liver CSC self-renewal and tumorigenesis by up-regulating PTEN levels. In conclusion, by binding to EZH2, SNHG9 down-regulated PTEN levels, promoting liver CSC self-renewal and tumor formation, and exacerbating HCC progression.

The role of CD133 in hepatocellular carcinoma

Cancer stem cells (CSCs) represent a small subpopulation of cells found within tumors that exhibit properties of self-renewal, like normal stem cells. CSCs have been defined as a crucial factor involved in driving cancer relapse, chemoresistance and metastasis. Prominin-1 (CD133) is one of the most well-characterized markers of CSCs in various tumor types, including hepatocellular carcinoma (HCC). CD133+ cells have been demonstrated to be involved in metastasis, tumorigenesis, tumor recurrence, and resistance to treatment in HCC. CD133-related clinical prognosis prediction, and targeted therapy have highlighted the clinical significance of CD133 in HCC. However, there remains controversy over the role of CD133 in experimental and clinical research involving HCC. In this article, we summarize the fundamental cell biology of CD133 in HCC cells and discuss the important characteristics of CD133+ in HCC cells. Furthermore, the prognostic value of CD133, and therapeutic strategies for its targeting in HCC, is also reviewed.

LncRNAs link cancer stemness to therapy resistance

Cancer stem cells (CSCs) are a cellular subpopulation accelerating cancer cell growth, invasion and metastasis and survival. After chemoradiotherapy, CSCs are enriched because of their survival advantages and lead to tumor relapse and metastasis. Elimination of CSCs is critically important for the radical treatment of human cancers. Long non-coding RNAs (lncRNAs) are a group of RNAs longer than 200 nucleotides and have no protein-coding potential. Aberrant expressions of lncRNAs are associated with human diseases including cancer. LncRNAs function as cancer biomarkers, prognostic factors and therapeutic targets. They induce cancer stemness by chromatin modification, transcriptional regulation or post-transcriptional regulation of target genes as a sponge or through assembling a scaffold complex. Several factors caused aberrant expressions of lncRNAs in CSCs such as genes mutations, epigenetic alteration and environmental stimuli. Targeting of lncRNAs has been demonstrated to significantly reverse the chemoradioresistance of CSCs. In this review, we have summarized the progress of studies regarding lncRNAs-mediated therapy resistance of CSCs and clarified the molecular mechanisms. Furthermore, we have for the first time analyzed the influences of lncRNAs on cell metabolism and emphasized the effect of tumor microenvironment on lncRNAs functions in CSCs. Overall, the thorough understanding of the association of lncRNAs and CSCs would contribute to the reversal of therapy resistance.

Unraveling the Molecular Nexus between GPCRs, ERS, and EMT

G protein-coupled receptors (GPCRs) represent a large family of transmembrane proteins that transduce an external stimulus into a variety of cellular responses. They play a critical role in various pathological conditions in humans, including cancer, by regulating a number of key processes involved in tumor formation and progression. The epithelial-mesenchymal transition (EMT) is a fundamental process in promoting cancer cell invasion and tumor dissemination leading to metastasis, an often intractable state of the disease. Uncontrolled proliferation and persistent metabolism of cancer cells also induce oxidative stress, hypoxia, and depletion of growth factors and nutrients. These disturbances lead to the accumulation of misfolded proteins in the endoplasmic reticulum (ER) and induce a cellular condition called ER stress (ERS) which is counteracted by activation of the unfolded protein response (UPR). Many GPCRs modulate ERS and UPR signaling via ERS sensors, IRE1α, PERK, and ATF6, to support cancer cell survival and inhibit cell death. By regulating downstream signaling pathways such as NF-κB, MAPK/ERK, PI3K/AKT, TGF-β, and Wnt/β-catenin, GPCRs also upregulate mesenchymal transcription factors including Snail, ZEB, and Twist superfamilies which regulate cell polarity, cytoskeleton remodeling, migration, and invasion. Likewise, ERS-induced UPR upregulates gene transcription and expression of proteins related to EMT enhancing tumor aggressiveness. Though GPCRs are attractive therapeutic targets in cancer biology, much less is known about their roles in regulating ERS and EMT. Here, we will discuss the interplay in GPCR-ERS linked to the EMT process of cancer cells, with a particular focus on oncogenes and molecular signaling pathways.

Changes in expression of orphan receptors GPR99 and GPR107 during the development and establishment of hypertension in spontaneously hypertensive rats

Hypertension is a disease, which in spite of existing treatments continues to have high morbidity and mortality, which suggests that there are other mechanisms involved in this pathology. In this sense, the orphan receptors are G protein-coupled receptor associated with various pathologies such as GPR99 which has been linked to mice develop left ventricular hypertrophy induced by blood pressure overload while GPR107 with patients with idiopathic pulmonary arterial hypertension. For this reason, the aim of this work was to study if the expression of the orphan receptors GPR99 and GPR107 are modified by arterial hypertension. Male SHR and WKY rats of 6-8 and 10-12 weeks old were used. The weight, systolic blood pressure and heart rate were measured, as well as the mRNA of the receptors GPR99 and GPR107 in the aorta, kidney, heart and brain by RT-PCR, also was realized an in silico analysis to predict which G protein could be coupled the orphan receptor GPR107. Our results showed that receptors GPR99 and GPR107 are expressed in the analyzed tissues and their expression profile tends to change at different ages and with the development of hypertension, for the other hand, the bioinformatics analysis for GPR107 showed that is coupled to Gi protein. Therefore, we do not rule out that GPR99 and GPR107 could be involved in the pathophysiology of hypertension and could be used as targets therapeutic in hypertension.

Unleashing the Diagnostic, Prognostic and Therapeutic Potential of the Neuronostatin/GPR107 System in Prostate Cancer

Certain components of the somatostatin-system play relevant roles in Prostate Cancer (PCa), whose most aggressive phenotype (Castration-Resistant-PCa (CRPC)) remains lethal nowadays. However, neuronostatin and the G protein-coupled receptor 107 (GPR107), two novel members of the somatostatin-system, have not been explored yet in PCa. Consequently, we investigated the pathophysiological role of NST/GPR107-system in PCa. GPR107 expression was analyzed in well-characterized PCa patient's cohorts, and functional/mechanistic assays were performed in response to GPR107-silencing and NST-treatment in PCa cells (androgen-dependent (AD: LNCaP) and androgen-independent (AI: 22Rv1/PC-3), which are cell models of hormone-sensitive and CRPC, respectively), and normal prostate cells (RWPE-1 cell-line). GPR107 was overexpressed in PCa and associated with key clinical parameters (e.g., advance stage of PCa, presence of vascular invasion and metastasis). Furthermore, GPR107-silencing inhibited proliferation/migration rates in AI-PCa-cells and altered key genes and oncogenic signaling-pathways involved in PCa aggressiveness (i.e., KI67/CDKN2D/MMP9/PRPF40A, SST5TMD4/AR-v7/In1-ghrelin/EZH2 splicing-variants and AKT-signaling). Interestingly, NST treatment inhibited proliferation/migration only in AI-PCa cells and evoked an identical molecular response than GPR107-silencing. Finally, NST decreased GPR107 expression exclusively in AI-PCa-cells, suggesting that part of the specific antitumor effects of NST could be mediated through a GPR107-downregulation. Altogether, NST/GPR107-system could represent a valuable diagnostic and prognostic tool and a promising novel therapeutic target for PCa and CRPC.

The Underlying Mechanisms of Noncoding RNAs in the Chemoresistance of Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most lethal human malignancies. Chemotherapeutic agents, such as sorafenib and lenvatinib, can improve the outcomes of HCC patients. Nevertheless, chemoresistance has become a major hurdle in the effective treatment of HCC. Noncoding RNAs (ncRNAs), including mircoRNAs (miRNAs), long ncRNAs (lncRNAs), and circular RNAs (circRNAs), have been demonstrated to participate in the onset and progression of HCC. Moreover, multiple lines of evidence have indicated that ncRNAs also play a pivotal role in HCC drug resistance. ncRNAs can regulate drug efflux and metabolism, glucose metabolism, cellular death pathways, and malignant characteristics in HCC. A deeper understanding of the molecular mechanisms responsible for ncRNA-mediated drug resistance in HCC will provide new opportunities for improving the treatment of HCC. In this review, we summarize recent findings on the molecular mechanisms by which ncRNAs regulate HCC chemoresistance, as well as their potential clinical implications in overcoming HCC chemoresistance.

Mechanism of long noncoding RNAs as transcriptional regulators in cancer

Dysregulation of gene expression, often interpreted by gene transcription as an endpoint response, is tightly associated with human cancer. Long noncoding RNAs (lncRNAs), derived from the noncoding elements in the genome and appeared no less than 200nt in length, have emerged as a novel class of pivotal regulatory component. Recently, great attention has been paid to the cancer-related lncRNAs and growing evidence have shown that lncRNAs act as key transcriptional regulators in cancer cells through diverse mechanisms. Here, we focus on the nucleus-expressed lncRNAs and summarize their molecular mechanisms in transcriptional control during tumorigenesis and cancer metastasis. Six major mechanisms will be discussed in this review: association with transcriptional factor, modulating DNA methylation or histone modification enzyme, influencing on chromatin remodelling complex, facilitating chromosomal looping, interaction with RNA polymerase and direct association with promoter.

LncRNA GClnc1 promotes proliferation and invasion of bladder cancer through activation of MYC

Various studies demonstrate that long noncoding RNAs (lncRNAs) act as oncogenes or tumor suppressors in cancer. However, the function of lncRNAs in bladder cancer still remains largely unknown. In this study, we identified an lncRNA, gastric cancer-associated lncRNA1 (GClnc1), which was in high abundance in bladder cancer tissues and its expression was related to poor survival rates in patients with bladder cancer. In vitro and in vivo assays showed that GClnc1 significantly promoted cell proliferation, metastasis, and invasiveness in bladder cancer. Mechanistically, we first found that GClnc1 bound to LIN28B and promoted the expression of myelocytomatosis proto-oncogene (MYC) through the LIN28B/let-7a/MYC pathway. In short, GClnc1 is clinically, functionally, and mechanistically oncogenic in bladder cancer. GClnc1 may be a potential target for treating patients with bladder cancer.-Zhuang, C., Ma, Q., Zhuang, C., Ye, J., Zhang, F., Gui, Y. LncRNA GClnc1 promotes proliferation and invasion of bladder cancer through activation of MYC.

Unique features in the intracellular transport of typhoid toxin revealed by a genome-wide screen

Typhoid toxin is a virulence factor for Salmonella Typhi and Paratyphi, the cause of typhoid fever in humans. This toxin has a unique architecture in that its pentameric B subunit, made of PltB, is linked to two enzymatic A subunits, the ADP ribosyl transferase PltA and the deoxyribonuclease CdtB. Typhoid toxin is uniquely adapted to humans, recognizing surface glycoprotein sialoglycans terminated in acetyl neuraminic acid, which are preferentially expressed by human cells. The transport pathway to its cellular targets followed by typhoid toxin after receptor binding is currently unknown. Through a genome-wide CRISPR/Cas9-mediated screen we have characterized the mechanisms by which typhoid toxin is transported within human cells. We found that typhoid toxin hijacks specific elements of the retrograde transport and endoplasmic reticulum-associated degradation machineries to reach its subcellular destination within target cells. Our study reveals unique and common features in the transport mechanisms of bacterial toxins that could serve as the bases for the development of novel anti-toxin therapeutic strategies.

Effect of WEE1 inhibitor MK-1775 on self-renewal of gallbladder cancer stem cells

AIM

To assess the inhibitory effect of Wee1 inhibitor MK-1775 on self-renewal of cancer stem like cells in GBC-SD cells.

METHODS

The GBC-SD cell line was cultured in vitro, and the suspended cancer stem cell spheres were cultured in serum free stem cell culture medium containing MK-1775. The expression of Wee1 was detected by Western blot, and the changes of the sphere size and sphere formation rate were analyzed. After the establishment of a subcutaneously transplanted tumor model in nude mice, MK-17751 was given for 2 wk, and the weight of the transplanted tumors was detected 2 wk later.

RESULTS

After 8 d of culture with MK-1775, the expression of Wee1 in GBC-SD cells was downregulated and the sphere size and sphere formation rate were reduced. After MK-17751 treatment, the growth of subcutaneous xenografts in nude mice was inhibited.

CONCLUSION

MK-1775 can inhibit the self-renewal of cancer stem like cell in gallbladder cancer GBC-SD cells.