Differential Ire1 determines loser cell fate in tumor-suppressive cell competition

Tumor-suppressive cell competition (TSCC) is a conserved surveillance mechanism in which neighboring cells actively eliminate oncogenic cells. Despite overwhelming studies showing that the unfolded protein response (UPR) is dysregulated in various tumors, it remains debatable whether the UPR restrains or promotes tumorigenesis. Here, using Drosophila eye epithelium as a model, we uncover a surprising decisive role of the Ire1 branch of the UPR in regulating cell polarity gene scribble (scrib) loss-induced TSCC. Both mutation and hyperactivation of Ire1 accelerate elimination of scrib clones via inducing apoptosis and autophagy, respectively. Unexpectedly, relative Ire1 activity is also crucial for determining loser cell fate, as dysregulating Ire1 signaling in the surrounding healthy cells reversed the "loser" status of scrib clones by decreasing their apoptosis. Furthermore, we show that Ire1 is required for cell competition in mammalian cells. Together, these findings provide molecular insights into scrib-mediated TSCC and highlight Ire1 as a key determinant of loser cell fate.

Ultrasound Molecular Imaging of Epithelial Mesenchymal Transition for Evaluating Tumor Metastatic Potential via Targeted Biosynthetic Gas Vesicles

Epithelial mesenchymal transition (EMT) of tumor cells is recognized as the main driver to promote metastasis. Extensive researches suggest that gradually decreased E-cadherin (E-cad) and increased N-cadherin (N-cad) exist in the tumor cells during the EMT process. However, there still lacks suitable imaging methods to monitor the status of EMT for evaluating tumor metastatic potentials. Herein, the E-cad-targeted and N-cad-targeted gas vesicles (GVs) are developed as the acoustic probes to monitor the EMT status in tumor. The resulting probes have ≈200 nm particle size and good tumor cell targeting performance. Upon systemic administration, E-cad-GVs and N-cad-GVs can traverse through blood vessels and bind to the tumor cells, producing strong contrast imaging signals in comparison with the nontargeted GVs. The contrast imaging signals correlate well with the expression levels of E-cad and N-cad and tumor metastatic ability. This study provides a new strategy to noninvasively monitor the EMT status and help to evaluate tumor metastatic potential in vivo.

A reliable mouse model of liver and lung metastasis by injecting esophageal cancer stem cells (CSCs) through tail-vein injection

BACKGROUND

Esophageal Squamous Cell Carcinoma (ESCC) is a highly aggressive tumor with increased metastatic potential. Recent evidence suggests that esophageal CSCs have a crucial role in tumor initiation, progression, and resistance to conventional anti-cancer therapies. The study aimed to develop mouse model to mimic the late steps of the metastasis process using a tail-vein injection of esophageal CSCs.

METHODS AND RESULTS

The sphere formation assay was used to enrich CSCs. For analysis of tumorigenicity, YM-1 adherent cells and enriched CSCs were injected subcutaneously into dorsal flank of nude mice. The expression of SLUG, E-cad, and CTHRC1 genes was examined by Real-Time qRT-PCR and immunohistochemistry (IHC) methods. To assess the metastatic potential of adherent YM-1 cells and their enriched CSCs, we injected the cells into the tail vein of nude mice. Our findings showed the up-regulation of SLUG and down-regulation of E-cad in the esophageal CSC-derived tumors (ECSCTs) compared to adherent cells-derived tumors. There was no statistically significant difference between CTHRC1 gene expressions in both groups of tumors. IHC staining confirmed the higher expression of SLUG protein in ECSCTs compared to adherent cell-derived tumors. Enriched CSCs were able to metastasize to the lungs and livers after three months, but, metastasis of adherent cells wasn't observed.

CONCLUSION

Our study showed esophageal CSCs injected through the tail-vein injection can migrate and metastasize to the lung and liver after three months. The developed metastatic mouse model can be a valuable and relevant model to investigate the molecular and cellular mechanisms of metastasis and develop successful targeted therapies against ESCC. The present study is one of the few studies that investigate the metastasis of esophageal cancer stem cells (ESCC type) through injection into the tail vein of nude mice.

Runx2 deficiency in junctional epithelium of mouse molars decreases the expressions of E-cadherin and junctional adhesion molecule 1

Junctional epithelium (JE) attaching to the enamel surface seals gaps around the teeth, functioning as the first line of gingival defense. Runt-related transcription factor 2 (Runx2) plays a role in epithelial cell fate, and the deficiency of Runx2 in JE causes periodontal destruction, while its effect on the barrier function of JE remains largely unexplored. In the present study, hematoxylin-eosin (H&E) staining revealed the morphological differences of JE between wild-type (WT) and Runx2 conditional knockout (cKO) mice. We speculated that these changes were related to the down-regulation of E-cadherin (E-cad), junctional adhesion molecule 1 (JAM1), and integrin β6 (ITGB6) in JE. Moreover, immunohistochemistry (IHC) was conducted to assess the expressions of these proteins. To verify the relationship between Runx2 and the three above-mentioned proteins, human gingival epithelial cells (HGEs) were cultured for in vitro experiment. The expression of Runx2 in HEGs was depleted by lentivirus. Quantitative real-time PCR (qRT-PCR) and Western blotting analysis were adopted to analyze the differences in mRNA and protein expressions. Taken together, Runx2 played a crucial role in maintaining the structure and function integrality of JE via regulating the expressions of E-cad and JAM1.

Aberrant expression of MYH9 and E-cadherin in esophageal squamous cell carcinoma and their relationship to vasculogenic mimicry

PURPOSE

To investigate whether vasculogenic mimicry (VM) exists in esophageal squamous cell carcinoma (ESCC) and to elucidate the relationship among expression of MYH9, E-cadherin and VM.

METHODS

The expression of MYH9 (non-muscle myosin heavy chain 9), E-cadherin protein and VM in 120 specimens of esophageal squamous cell carcinoma (ESCC) and 120 specimens of normal esophageal mucosa were detected by using immunohistochemical and histochemical staining.

RESULTS

VM channels were identified in 58 (48.33%) of the 120 ESCC specimens and none of the normal esophageal mucosa was found to have VM. The rates of expression of MYH9 and E-cad in ESCC were 57.50% and 40.00%, while rates in the control group were 13.33% and 73.33%, respectively (P<0.05). VM and the expression levels of MYH9 and E-cad were significantly connected with lymph node metastasis, serosa invasion, pTNM staging and 5-year-survival rates of patients with ESCC (P<0.05). VM was positively correlated with MYH9, but negatively correlated with E-cad, and MYH9 was negatively significantly correlated with E-cad. The 5-year-survival rates of patients with ESCC were 6.89% (4/58) in the VM group and 67.74% (42/62) in the non-VM group, 8.00% (4/50) in high MYH9 expression group and 60.00% (42/70) in low MYH9 expression group. However, the 5-year-survival rate in high E-cad expression group was 86.95% (40/46) and that in low E-cad expression group was 8.11% (6/74) (P<0.05). Cox multifactorial regression analysis demonstrated that lymph node metastasis, pTNM stage, VM and expression levels of MYH9 and E-cad were independent risk factors in patients with ESCC (P<0.05).

CONCLUSION

ESCC'patients with VM had a poor differentiation and a bad clinical prognosis; Combined detection of VM, MYH9 and E-cad may play an essential role in predicting the invasion, metastasis, and progression of patients with ESCC.

Raddeanin A induces human gastric cancer cells apoptosis and inhibits their invasion in vitro. Biochem Biophys Res Commun. 2013;439:196-202. [PMID: 23988447 DOI: 10.1016/j.bbrc.2013.08.060]

Raddeanin A is one of the triterpenoid saponins in herbal medicine Anemone raddeana Regel which was reported to suppress the growth of liver and lung cancer cells. However, little was known about its effect on gastric cancer (GC) cells. This study aimed to investigate its inhibitory effect on three kinds of different differentiation stage GC cells (BGC-823, SGC-7901 and MKN-28) in vitro and the possible mechanisms. Proliferation assay and flow cytometry demonstrated Raddeanin A's dose-dependent inhibitory effect and determined its induction of cells apoptosis, respectively. Transwell assay, wounding heal assay and cell matrix adhesion assay showed that Raddeanin A significantly inhibited the abilities of the invasion, migration and adhesion of the BGC-823 cells. Moreover, quantitative real time PCR and Western blot analysis found that Raddeanin A increased Bax expression while reduced Bcl-2, Bcl-xL and Survivin expressions and significantly activated caspase-3, caspase-8, caspase-9 and poly-ADP ribose polymerase (PARP). Besides, Raddeanin A could also up-regulate the expression of reversion inducing cysteine rich protein with Kazal motifs (RECK), E-cadherin (E-cad) and down-regulate the expression of matrix metalloproteinases-2 (MMP-2), MMP-9, MMP-14 and Rhoc. In conclusion, Raddeanin A inhibits proliferation of human GC cells, induces their apoptosis and inhibits the abilities of invasion, migration and adhesion, exhibiting potential to become antitumor drug.

E-cadherin supports steady-state Rho signaling at the epithelial zonula adherens

In simple polarized epithelial cells, the Rho GTPase commonly localizes to E-cadherin-based cell-cell junctions, such as the zonula adherens (ZA), where it regulates the actomyosin cytoskeleton to support junctional integrity and tension. An important question is how E-cadherin contributes to Rho signaling, notably whether junctional Rho may depend on cadherin adhesion. We sought to investigate this by assessing Rho localization and activity in epithelial monolayers depleted of E-cadherin by RNAi. We report that E-cadherin depletion reduced both Rho and Rho-GTP at the ZA, an effect that was rescued by expressing a RNAi-resistant full-length E-cadherin transgene. This impact on Rho signaling was accompanied by reduced junctional localization of the Rho GEF ECT2 and the centralspindlin complex that recruits ECT2. Further, the Rho signaling pathway contributes to the selective stabilization of E-cadherin molecules in the apical zone of the cells compared with E-cadherin at the lateral surface, thereby creating a more defined and restricted pool of E-cadherin that forms the ZA. Thus, E-cadherin and Rho signaling cooperate to ensure proper ZA architecture and function.