Stomatin-like protein 2 is associated with the clinicopathological features of human papillary thyroid cancer and is regulated by TGF-β in thyroid cancer cells

Diagnostic and prognostic utility of TROP-2, SLP-2, and CXCL12 expression in papillary thyroid carcinoma

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most frequent thyroid malignancy. Histopathological examination is widely accepted as the gold standard test for the diagnosis of PTC. However, the histopathological examination sometimes can't differentiate PTC from other thyroid diseases. Differentiating PTC from other thyroid diseases is essential for a therapeutic approach and prognosis.

OBJECTIVES

The current study was performed to investigate the utility of TROP-2, SPL-2, and CXCL12 mRNA and protein expression in discriminating PTC from other thyroid diseases that mimic PTC.

METHODS

The current study was performed on 75 cases of surgically resected thyroid glands. The cases were distributed in two groups: the PTC group and the non-PTC group. The PTC group consisted of 35 cases (25 patients of the classic PTC variant and 10 patients of the PTC follicular variant). The non-PTC group consisted of 40 cases (10 cases were multinodular goiter, 5 cases were Graves' disease, 5 cases were Hashimoto thyroiditis, 15 patients were follicular adenoma (FA) and 5 cases were follicular carcinoma). TROP-2, SPL-2, and CXCL12 mRNA expression were estimated by qRT-PCR, and protein expression was estimated by immunohistochemistry.

RESULTS

There were upregulated TROP-2, SPL-2, and CXCL12 mRNA and protein expressions in PTC compared to non-PTC (P< 0.001, for each). There was a statistically significant upregulation in the mRNA expression of the three genes among PTC cases with larger tumor sizes (P< 0.001, for each), those with tumor stages III and IV (P= 0.008, 0.002 and < 0.001 respectively), and those with LN metastasis (P< 0.001, for each). Moreover, there was a statistically significant upregulation in CXCL-12 gene expression among PTC cases with extra-thyroid extension (P< 0.001).

CONCLUSION

mRNA expression of TROP-2, SPL-2, and CXCL12 among PTC cases increased in larger tumor size, tumor stages III and IV, and LN metastasis. Moreover, there was an increase in CXCL-12 gene expression among PTC cases with extra-thyroid extension. Thus, TROP-2, SPL-2, and CXCL12 expressions could be possible diagnostic and prognostic markers in PTC.

STOML2 interacts with PHB through activating MAPK signaling pathway to promote colorectal Cancer proliferation

BACKGROUND

Highly expressed STOML2 has been reported in a variety of cancers, yet few have detailed its function and regulatory mechanism. This research aims to reveal regulatory mechanism of STOML2 and to provide evidence for clinical therapeutics, via exploration of its role in colorectal cancer, and identification of its interacting protein.

METHODS

Expression level of STOML2 in normal colon and CRC tissue from biobank in Nanfang Hospital was detected by pathologic methods. The malignant proliferation of CRC induced by STOML2 was validated via gain-of-function and loss-of-function experiments, with novel techniques applied, such as organoid culture, orthotopic model and endoscopy monitoring. Yeast two-hybrid assay screened interacting proteins of STOML2, followed by bioinformatics analysis to predict biological function and signaling pathway of candidate proteins. Target protein with most functional similarity to STOML2 was validated with co-immunoprecipitation, and immunofluorescence were conducted to co-localize STOML2 and PHB. Pathway regulated by STOML2 was detected with immunoblotting, and subsequent experimental therapy was conducted with RAF inhibitor Sorafenib.

RESULTS

STOML2 was significantly overexpressed in colorectal cancer and its elevation was associated with unfavorable prognosis. Knockdown of STOML2 suppressed proliferation of colorectal cancer, thus attenuated subcutaneous and orthotopic tumor growth, while overexpressed STOML2 promoted proliferation in cell lines and organoids. A list of 13 interacting proteins was screened out by yeast two-hybrid assay. DTYMK and PHB were identified to be most similar to STOML2 according to bioinformatics in terms of biological process and signaling pathways; however, co-immunoprecipitation confirmed interaction between STOML2 and PHB, rather than DTYMK, despite its highest rank in previous analysis. Co-localization between STOML2 and PHB was confirmed in cell lines and tissue level. Furthermore, knockdown of STOML2 downregulated phosphorylation of RAF1, MEK1/2, and ERK1/2 on the MAPK signaling pathway, indicating common pathway activated by STOML2 and PHB in colorectal cancer proliferation.

CONCLUSIONS

This study demonstrated that in colorectal cancer, STOML2 expression is elevated and interacts with PHB through activating MAPK signaling pathway, to promote proliferation both in vitro and in vivo. In addition, combination of screening assay and bioinformatics marks great significance in methodology to explore regulatory mechanism of protein of interest.

Stomatin-like Protein 2 Promotes Tumor Cell Survival by Activating the JAK2-STAT3-PIM1 Pathway, Suggesting a Novel Therapy in CRC

Despite intensive efforts, a considerable proportion of colorectal cancer (CRC) patients develop local recurrence and distant metastasis. Stomatin-like protein 2 (SLP-2), a member of the highly conserved stomatin superfamily, is upregulated across cancer types. However, the biological and functional roles of SLP-2 remain elusive in CRC. Here, we report that high SLP-2 expression was found in CRC tissues and was linked to tumor progression and tumor cell differentiation. Additionally, high SLP-2 expression correlated with poor overall survival (OS) in CRC patients (p < 0.001). SLP-2 knockout (SLP-2KO), generated by CRISPR/Cas9, reduced cell growth, migration, and invasion; induced apoptosis in CRC cells; and reduced tumor xenograft growth in vivo. A 181-compound library screening showed that SLP-2KO produced resistance to JAK2 inhibitors (NVP-BSK805 and TG-101348) and a PIM1 inhibitor (SGI-1776), revealing that the JAK2-STAT3-PIM1 oncogenic pathway was potentially controlled by SLP-2 in CRC. In vitro and in vivo, TG-101348 combined with SGI-1776 was synergistic in CRC (combination index [CI] < 1). Overall, our findings suggest that SLP-2 controls the JAK2-STAT3-PIM1 oncogenic pathway, offering a rationale for a novel therapeutic strategy with combined SGI-1776 and TG-101348 in CRC. Additionally, SLP-2 may be a prognostic marker and biomarker for sensitivity to JAK2 and PIM1 inhibitors.

Stomatin-like protein-2 confers neuroprotection effect in oxygen-glucose deprivation/reoxygenation-injured neurons by regulating AMPK/Nrf2 signalling

Stomatin-like protein-2 (SLP-2) has emerged as a cytoprotective protein that confers a protective effect against various stresses. However, whether SLP-2 confers neuroprotection during cerebral ischemia/reperfusion injury remains unclear. In the present study, we investigated the role of SLP-2 in regulating oxygen-glucose deprivation/reoxygenation (OGD/R)-induced apoptosis and oxidative stress, which has been used as an in vitro model of cerebral ischemia/reperfusion injury. We found that OGD/R treatment resulted in a significant reduction in SLP-2 expression in neurons. Functional experiments demonstrated that SLP-2 overexpression significantly increased cell viability and decreased cell apoptosis and reactive oxygen species (ROS) production in OGD/R-exposed neurons, while SLP-2 inhibition showed the opposite effect. Notably, SLP-2 overexpression was shown to up-regulate the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK). In addition, SLP-2 overexpression increased the nuclear expression of nuclear factor (erythroid-derived 2)-like 2 and reinforced the activity of Nrf2/antioxidant response element (ARE)-mediated transcription. However, AMPK inhibition or Nrf2/ARE inhibition partially reversed SLP-2-mediated neuroprotection effect in OGD/R-exposed neurons. Taken together, these results demonstrate that SLP-2 confers neuroprotection effect in OGD/R-injured neurons associated with reinforcing AMPK/Nrf2 signalling, suggesting SLP-2 as a potential therapeutic target for cerebral ischemia/reperfusion injury.

A Positive Feedback Loop of SLP2 Activates MAPK Signaling Pathway to Promote Gastric Cancer Progression

Rationale: This study is to validate the clinicopathologic significance and potential prognostic value of SLP2 in gastric cancer (GC), to investigate the biological function and regulation mechanism of SLP2, and to explore potential therapeutic strategies for GC.

Methods: The expression of SLP2 in GC tissues from two cohorts was examined by IHC. The biological function and regulation mechanism of SLP2 and PHB was validated via loss-of-function or gain-of-function experiments. In vitro proliferation detection was used to evaluate the therapeutic effects of Sorafenib.

Results: We validated that SLP2 was significantly elevated in GC tissues and its elevation was associated with poor prognosis of patients. Loss of SLP2 drastically suppressed the proliferation of GC cells and inhibited the tumor growth, while SLP2 overexpression promoted the progression of GC. Mechanistically, SLP2 competed against E3 ubiquitin ligase SKP2 to bind with PHB and stabilized its expression. Loss of SLP2 significantly suppressed phosphorylation of Raf1, MEK1/2, ERK1/2 and ELK1. Furthermore, phosphorylated ELK1 could in turn activate transcription of SLP2. Finally, we demonstrated that a Raf1 inhibitor, Sorafenib, was sufficient to inhibit the proliferation of GC cells.

Conclusion: Our findings demonstrated a positive feedback loop of SLP2 which leads to acceleration of tumor progression and poor survival of GC patients. This finding also provided evidence for the reason of SLP2 elevation. Moreover, we found that sorafenib might be a potential therapeutic drug for GC and disrupting the interaction between SLP2 and PHB might also serve as a potential therapeutic target in GC.

The diagnostic value of TROP-2, SLP-2 and CD56 expression in papillary thyroid carcinoma

OBJECTIVE

The study aimed to explore some novel diagnostic biomarkers for papillary thyroid carcinoma (PTC) by identifying the different expression of TROP-2, SLP-2 and CD56 in benign and malignant thyroid lesions.

METHODS

We evaluated the mRNA expressions of TROP-2 and SLP-2 in fine needle aspirates (FNAs) which contained 10 PTCs and 10 benign follicular adenomas (FAs) using quantitative real-time PCR (qRT-PCR). Immunohistochemical (IHC) staining of TROP-2, SLP-2 and CD56 was also performed on postoperative samples of 30 PTCs and 29 FAs. Membranous or cytoplasmic staining in > 10% of cells was considered as positive. Diagnostic sensitivity, specificity, positive predictive value, negative predictive value (NPV) and diagnostic accuracy of these three biomarkers were carried out. We further analyzed the associations between the clinical features and the expressions of markers in PTCs.

RESULTS

The mRNA expressions of both TROP-2 and SLP-2 were increased substantially in PTCs in comparison with those in FAs (P < 0.05). Similarly, IHC for these two proteins demonstrated higher positive staining in PTCs than in FAs (96.5% vs. 12.5% for TROP-2, 83.3% vs. 20.7% for SLP-2, P < 0.05). Conversely, CD56 expression was lost with 86.7% of PTCs. In identifying malignancy, TROP-2 was the most sensitive marker and CD56 was the most specific one. When the markers were combined, the sensitivity and NPV increased to 100% and had better diagnostic accuracy. However, no association was found between biomarker expressions and clinicopathological factors in PTCs.

CONCLUSIONS

We found that TROP-2, SLP-2 and CD56 were effective diagnostic markers for PTC, especially when they were combined to use.

Development of a multiplexed tumor-associated autoantibody-based blood test for the detection of colorectal cancer

BACKGROUND

Colorectal cancer (CRC) is one of the most common malignancies worldwide, and early diagnosis is vital to improving prognoses. We explored the diagnostic potential of a multiplex autoantibody panel as a biomarker for the detection of CRC by ELISA.

METHODS

In total, 192 serum samples (92 CRC and 100 matched controls) were tested against a panel of 12 tumor-associated antigens (TAAs): RPH3AL, RPL36, SLP2, p53, survivin, ANAXA4, SEC61B, CCCAP, NYCO16, NMDAR, PLSCR1, and HDAC5. Individual and combined autoantibody signatures were examined.

RESULTS

Compared to individual autoantibody markers, the combinations of TAAs provided better discrimination between tumorous and normal sera. The overall sensitivity of a selected panel of four antibodies (anti-SLP2, -p53, -SEC61B, and -PLSCR1) was 64.1%, with a specificity of 80% that increased to 83.7% when carcinoembryonic antigen (CEA) measurement was added. Furthermore, the sensitivity of the panel of four antibodies for early and advanced stages of CRC was 66.7% and 62%, increasing to 88.3% and 84%, respectively, when CEA was added.

CONCLUSIONS

We identified a panel of four antibodies as a promising diagnostic biomarker for the detection of CRC.

Stomatin-like protein 2 of turbot Scopthalmus maximus: Gene cloning, expression profiling and immunoregulatory properties

Stomatin-like protein 2 (SLP-2) is a novel and unusual member of the stomatin gene superfamily. In this study, we obtained a full-length SLP-2 (SmSLP-2) cDNA from turbot (Scopthalmus maximus) spleen cDNA library. The cDNA sequence of SmSLP-2 contains a 5'-UTR of 107 bp, an ORF of 1050 bp, and a 3'-UTR of 959 bp. The ORF encodes a putative protein of 349 residues, which has a calculated molecular mass of 38.7 kDa. The SmSLP-2 protein possesses a prohibitin-homology (PHB) domain (residues 40 to 198) and shares 72.4-87.6% overall sequence identity with that of the teleost species. The highest expression of SmSLP-2 mRNA was found in the skin, followed by the head kidney, gut, spleen, liver, heart, gill and muscle. Moreover, both viral and bacterial pathogen infection resulted in the up-regulation of SmSLP-2 mRNA in the turbot head kidney and spleen in vivo. Subcellular localization analysis indicated that the SmSLP-2 proteins are mainly located in the peripheral membrane of ZF4 cells. This study also demonstrated that SmSLP-2 modulates IL-2 expression via active NFκB signaling pathway, and is possibly involved in host immune defense against bacterial and viral pathogens.

Stomatin-like protein 2 overexpression in papillary thyroid carcinoma is significantly associated with high-risk clinicopathological parameters and BRAFV600E mutation

Stomatin-like protein 2 (SLP-2), a member of the stomatin protein family, has emerged as a potential molecular hallmark of tumor progression in several human malignancies. The aim of this study was to analyze SLP-2 expression pattern in benign and malignant thyroid tumors (n = 210) and to examine its relationship with clinicopathological parameters and BRAFV600E mutation in thyroid cancer. SLP-2 immunohistochemical expression was not detected in benign adenomas and was absent/weak in follicular and anaplastic carcinomas. High expression levels of SLP-2, found only in papillary thyroid carcinoma (PTC), particularly in the classical variant, were significantly associated with adverse clinicopathological parameters: lymph node metastasis (p = 0.002), extrathyroid invasion (p < 0.001), pT status (p < 0.001), and advanced tumor stage (p = 0.001). Additional genotyping of PTC cases for the BRAFV600E mutation revealed for the first time a close relation between SLP-2 overexpression and the presence of BRAF mutation (p = 0.02) with high positive rates of lymph node metastasis (70%) and extrathyroid invasion (80%) in these cases. The significant association of SLP-2 overexpression with unfavorable clinicopathological characteristics and BRAFV600E mutation indicates that SLP-2 may have a role in aggressiveness of BRAF-mutated PTC and that SLP-2 evaluation could be clinically useful in identification of high-risk PTC patients.

miRNA-1207-5p is associated with cancer progression by targeting stomatin-like protein 2 in esophageal carcinoma

Newly discovered intrinsic regulators, the miRNAs regulate gene expression by binding to the 3'-untranslated regions of the genome. Accumulating studies have indicated that miRNAs are aberrantly expressed in various human cancers. We found that miRNA-1207-5p (miR‑1207-5p) was markedly downregulated in esophageal carcinoma (EC) tissues, and was correlated with EC differentiation, pathological stage and lymph node metastasis. Rates of apoptosis were increased and cell invasion ability was decreased in EC9706 and EC-1 cells transfected with a miR‑1207-5p mimic. Stomatin-like protein 2 (STOML-2) was predicted to be a potential target of miR‑1207-5p by bioinformatics analysis and this was confirmed by luciferase assay and western blotting. Our study showed that STOML-2 was negatively regulated by miR‑1207-5p. Furthermore, overexpression of STOML-2 abolished the miR‑1207-5p anti-invasion function. Based on these results, we proposed that miR‑1207-5p might act as a potential therapeutic target in the treatment of EC.

BATF2 Deficiency Promotes Progression in Human Colorectal Cancer via Activation of HGF/MET Signaling: A Potential Rationale for Combining MET Inhibitors with IFNs

PURPOSE

BATF2, a novel IFN-stimulated gene, inhibits tumor cell proliferation, invasion, and migration. The objectives of this study were to determine how BATF2 expression is associated with colorectal cancer progression and patient outcome, to investigate how BATF2 overexpression inhibits hepatocyte growth factor (HGF)/MET signaling, and to elucidate the rationale for combining MET inhibitors with IFN.

EXPERIMENTAL DESIGN

BATF2 expression in colorectal cancer tissues was determined and correlated with colorectal cancer patient prognosis. Cultured colorectal cancer cells were used to investigate the effects of BATF2 overexpression on the malignant phenotype of colorectal cancer cells and HGF/MET signaling. Tumor xenograft models were used to validate the effects of BATF2 on colorectal cancer xenograft growth and assess the efficacy of the combination of MET inhibitors with IFNs in colorectal cancer.

RESULTS

In colorectal cancer tissues, BATF2 was found to be significantly downregulated, and its expression negatively correlated with MET expression. Decreased BATF2 expression was associated with progression and shorter patient survival in colorectal cancer. BATF2 overexpression promoted apoptosis and inhibited proliferation, migration, and invasion in colorectal cancer cells, as well as dramatically blunted tumor xenograft growth. In addition, MET inhibitors in combination with IFNβ produced synergistic cytotoxicity both in vitro and in vivo.

CONCLUSIONS

Together, these novel findings suggest that BATF2, a tumor suppressor gene, is a potent negative regulator of HGF/MET signaling in colorectal cancer and may serve as a prognostic tumor marker. Furthermore, these results provide a rationale for combining MET inhibitors with IFNs in preclinical trials.