Downregulation of RAI14 inhibits the proliferation and invasion of breast cancer cells

DSBSO-Based XL-MS Analysis of Breast Cancer PDX Tissues to Delineate Protein Interaction Network in Clinical Samples

Protein-protein interactions (PPIs) are fundamental to understanding biological systems as protein complexes are the active molecular modules critical for carrying out cellular functions. Dysfunctional PPIs have been associated with various diseases including cancer. Systems-wide PPI analysis not only sheds light on pathological mechanisms, but also represents a paradigm in identifying potential therapeutic targets. In recent years, cross-linking mass spectrometry (XL-MS) has emerged as a powerful tool for defining endogenous PPIs of cellular networks. While proteome-wide studies have been performed in cell lysates, intact cells and tissues, applications of XL-MS in clinical samples have not been reported. In this study, we adopted a DSBSO-based in vivo XL-MS platform to map interaction landscapes from two breast cancer patient-derived xenograft (PDX) models. As a result, we have generated a PDX interaction network comprising 2,557 human proteins and identified interactions unique to breast cancer subtypes. Interestingly, most of the observed differences in PPIs correlated well with protein abundance changes determined by TMT-based proteome quantitation. Collectively, this work has demonstrated the feasibility of XL-MS analysis in clinical samples, and established an analytical workflow for tissue cross-linking that can be generalized for mapping PPIs from patient samples in the future to dissect disease-relevant cellular networks.

The dual-crosslinked prospective values of RAI14 for the diagnosis and chemosurveillance in triple negative breast cancer

OBJECTIVE

The exploration of non-invasive biomarkers for assessing tumor response is critical to optimize treatment decisions. In this study, we aimed at determining the potential role of RAI14 in the early diagnosis and evaluation of chemotherapy efficacy in triple-negative breast cancer (TNBC).

METHODS

We recruited 116 patients newly diagnosed with breast cancer, 30 patients with benign breast disease and 30 healthy controls. In addition, 57 TNBC patients were collected in serum at different time points (C0, C2 and C4) for chemotherapy monitoring. The expression of serum RAI14 and CA15-3 were quantified by Elisa and electrochemiluminescence assay, respectively. Then we compared the performances of markers with the chemotherapy efficacy assessed by imaging.

RESULTS

RAI14 is significantly overexpressed in TNBC and is linked to adverse clinicopathological features such as tumor burden, CA15-3 levels and the ER, PR, and HER2 status of the patients. ROC curve analysis showed that RAI14 improves the diagnostic performance for CA15-3(AUCRAI14 = 0.934 vs. AUCCA15-3 = 0.836), especially embodied in early-stage breast cancer diagnosis and patients with CA15-3 negativity. Furthermore, RAI14 behaves well in reproducing treatment response which was consistent with clinical Imaging assessment.

CONCLUSIONS

Recent studies showed that RAI14 has a complementary effect to CA15-3 and a test combining the two parameters can improve the detection rate of early triple-negative breast cancer. At the same time, RAI14 plays a more important role in chemotherapy monitoring than CA15-3 as the change in its concentration is in line with the tumor volume variation. Taken together, RAI14 is a reliable novel marker in the early diagnosis and chemotherapy monitoring of triple-negative breast cancer.

New findings on the action of hypericin in hypoxic cancer cells with a focus on the modulation of side population cells

The presence of key hypoxia regulators, namely, hypoxia-inducible factor (HIF)-1α or HIF-2α, in tumors is associated with poor patient prognosis. Hypoxia massively activates several genes, including the one encoding the BCRP transporter that proffers multidrug resistance to cancer cells through the xenobiotic efflux and is a determinant of the side population (SP) associated with cancer stem-like phenotypes. As natural medicine comes to the fore, it is instinctive to look for natural agents possessing powerful features against cancer resistance. Hypericin, a pleiotropic agent found in Hypericum plants, is a good example as it is a BCRP substrate and potential inhibitor, and an SP and HIF modulator. Here, we showed that hypericin efficiently accumulated in hypoxic cancer cells, degraded HIF-1/2α, and decreased BCRP efflux together with hypoxia, thus diminishing the SP population. On the contrary, this seemingly favorable result was accompanied by the stimulated migration of this minor population that preserved the SP phenotype. Because hypoxia unexpectedly decreased the BCRP level and SP fraction, we compared the SP and non-SP proteomes and their changes under hypoxia in the A549 cell line. We identified differences among protein groups connected to the epithelial-mesenchymal transition, although major changes were related to hypoxia, as the upregulation of many proteins, including serpin E1, PLOD2 and LOXL2, that ultimately contribute to the initiation of the metastatic cascade was detected. Altogether, this study helps in clarifying the innate and hypoxia-triggered resistance of cancer cells and highlights the ambivalent role of natural agents in the biology of these cells.

Identification of critical prognosis signature associated with lymph node metastasis of stomach adenocarcinomas

Lymph node metastasis (LNM) is an important factor affecting the prognosis of patients with gastric adenocarcinoma (STAD), which is the most common malignancy of the human digestive system. Current detection techniques have limited sensitivity and specificity, and there is a lack of effective biomarkers to screen for LNM. Therefore, it is critical to screen for biomarkers that predict LNM in STAD. Gene expression differential analysis (false discovery rate < 0.05, |log₂Fold change| ≥1.5) was performed on 102 LNM samples, 224 non-LNM samples, and 29 normal gastric tissue samples from The Cancer Genome Atlas (TCGA) STAD dataset, and 269 LNM-specific genes (DEGs) were obtained. Enrichment analysis showed that LNM-specific genes functioned mainly in cytokine-cytokine receptor interactions, calcium signaling, and other pathways. Ten DEGs significantly associated with overall survival in STAD patients were screened by multivariate Cox regression, and an LNM-based 10-mRNA prognostic signature was established (Logrank P < 0.0001). This 10-mRNA signature was well predicted in both the TCGA training set and the Gene Expression Omnibus validation dataset (GSE84437) and was associated with survival in patients with LNM or advanced-stage STAD. Using Kaplan-Meier survival, receiver operating characteristic curve, C-index analysis, and decision curve analysis, the 10-mRNA signature was found to be a more effective predictor of prognosis in STAD patients than the other two reported models (P < 0.0005). Protein-protein interaction network and gene set enrichment analysis of the 10-mRNA signature revealed that the signature may affect the expression of multiple biological pathways and related genes. Finally, the expression levels of prognostic genes in STAD tissues and cell lines were verified using qRT-PCR, Western blot, and the Human Protein Atlas database. Taken together, the prognostic signature constructed in this study may become an indicator for clinical prognostic assessment of LNM-STAD and provide a new strategy for future targeted therapy.

ERβ1 Sensitizes and ERβ2 Desensitizes ERα-Positive Breast Cancer Cells to the Inhibitory Effects of Tamoxifen, Fulvestrant and Their Combination with All-Trans Retinoic Acid

Adjuvant endocrine therapy (AET) is the treatment of choice for early-stage estrogen receptor alpha (ERα)-positive breast cancer (BC). However, almost 40% of tamoxifen-treated cases display no response or a partial response to AET, thus increasing the need for new treatment options and strong predictors of the therapeutic response of patients at high risk of relapse. In addition to ERα, BC research has focused on ERβ1 and ERβ2 (isoforms of ERβ), the second ER isotype. At present, the impact of ERβ isoforms on ERα-positive BC prognosis and treatment remains elusive. In the present study, we established clones of MCF7 cells constitutively expressing human ERβ1 or ERβ2 and investigated their role in the response of MCF7 cells to antiestrogens [4-hydroxytamoxifen (OHΤ) and fulvestrant (ICI182,780)] and retinoids [all-trans retinoic acid (ATRA)]. We show that, compared to MCF7 cells, MCF7-ERβ1 and MCF7-ERβ2 cells were sensitized and desensitized, respectively, to the antiproliferative effect of the antiestrogens, ATRA and their combination and to the cytocidal effect of the combination of OHT and ATRA. Analysis of the global transcriptional changes upon OHT-ATRA combinatorial treatment revealed uniquely regulated genes associated with anticancer effects in MCF7-ERβ1 cells and cancer-promoting effects in MCF7-ERβ2 cells. Our data are favorable to ERβ1 being a marker of responsiveness and ERβ2 being a marker of resistance of MCF7 cells to antiestrogens alone and in combination with ATRA.

The deubiquitinating enzyme STAMBP is a newly discovered driver of triple-negative breast cancer progression that maintains RAI14 protein stability

Triple-negative breast cancer (TNBC) is a heterogeneous malignancy in women. It is associated with poor prognosis, aggressive malignant behavior, and limited treatment options. In the ubiquitin‒proteasome system (UPS), deubiquitinases (DUBs) are potential therapeutic targets for various tumors. In this study, by performing unbiased siRNA screening, we identified STAMBP, a JAMM metalloprotease in the DUB family, as a driver of human TNBC tumor growth. Functionally, the knockdown of STAMBP inhibited the proliferation, migration, and invasion of multiple TNBC cell lines. Immunoprecipitation-mass spectrometry combined with functional and morphological analysis verified the interaction between STAMBP and the actin-binding protein RAI14. Mechanistically, STAMBP stabilized the RAI14 protein by suppressing the K48-linked ubiquitination of RAI14 and thus prevented its proteasomal degradation. Therefore, knocking down STAMBP resulted in the reduction in RAI14 protein levels and suppression of tumor growth in vitro and in vivo. Importantly, high levels of STAMBP were correlated with poor prognosis in TNBC patients. In summary, we reveal a previously unrecognized DUB pathway that promotes TNBC progression and provides a rationale for potential therapeutic interventions for the treatment of TNBC.

RAI14 Promotes Melanoma Progression by Regulating the FBXO32/c-MYC Pathway

Melanoma originates from the malignant transformation of melanocytes. Compared with other skin cancers, melanoma has a higher fatality rate. The 5-year survival rate of patients with early-stage primary melanoma through surgical resection can reach more than 90%. However, the 5-year survival rate of patients with metastatic melanoma is only 25%. Therefore, accurate assessment of melanoma progression is critical. Previous studies have found that Retinoic Acid Induced 14(RAI14) is critical in tumorigenesis. However, the biological function of RAI14 for the development of melanoma is unclear. In this study, RAI14 is highly expressed in melanoma and correlated with prognosis. The expression of RAI14 can affect the proliferation, migration and invasion of melanoma cells. F-Box Protein 32(FBXO32) is an E3 ubiquitin ligase of c-MYC. We found that RAI14 affects the transcriptional expression of FBXO32 and regulates the stability of c-MYC. These results suggest that RAI14 play an important role in the growth of melanoma and is expected to be a therapeutic target for melanoma.

The emerging role of miR-653 in human cancer

MicroRNAs (miRNAs) refer to a family of non-coding RNA with ~22 nucleotides in length. A high number of studies show evidence that deregulation in miRNAs expression could be implicated in the processes of many pathologies such as cancer, hypoxia, and stroke. Herein, we aimed to summarize the miR-653 expression level and molecular mechanisms through which it functions in human cancer. It was found that variations in miR-653 expression are linked to tumor aggressiveness and unfavorable prognosis in human cancer, and it plays an inhibitory effect in some types of cancer, such as breast, cervical, liver, renal, and lung cancers. In contrast, it plays an acceleratory impact in some other cancers, such as bladder and prostate cancers. In gastric cancer, the role played by miR-653 is still controversial and will need to be elucidated in future studies. Future studies could definitely establish targeting miR-653 as a novel strategy in human cancer, from diagnosis to effective treatment.

Inward Outward Signaling in Ovarian Cancer: Morpho-Phospho-Proteomic Profiling Upon Application of Hypoxia and Shear Stress Characterizes the Adaptive Plasticity of OVCAR-3 and SKOV-3 Cells

With the onset of resistance, ovarian cancer cells display almost unpredictable adaptive potential. This may derive from the tumor genetic ancestry and can be additionally tailored by post translational protein modifications (PTMs). In this study, we took advantage of high-end (phospho)-proteome analysis combined with multiparametric morphometric profiling in high-grade serous (OVCAR-3) and non-serous (SKOV-3) ovarian carcinoma cells. For functional experiments, we applied two different protocols, representing typical conditions of the abdominal cavity and of the growing tumor tissue: on the one side hypoxia (oxygen 1%) which develops within the tumor mass or is experienced during migration/extravasation in non-vascularized areas. On the other hand, fluid shear stress (250 rpm, 2.8 dyn/cm²) which affects tumor surface in the peritoneum or metastases in the bloodstream. After 3 hours incubation, treatment groups were clearly distinguishable by PCA analysis. Whereas basal proteome profiles of OVCAR-3 and SKOV-3 cells appeared almost unchanged, phosphoproteome analysis revealed multiple regulatory events. These affected primarily cellular structure and proliferative potential and consolidated in the proteome signature after 24h treatment. Upon oxygen reduction, metabolism switched toward glycolysis (e.g. upregulation hexokinase-2; HK2) and cell size increased, in concerted regulation of pathways related to Rho-GTPases and/or cytoskeletal elements, resembling a vasculogenic mimicry response. Shear stress regulated proteins governing cell cycle and structure, as well as the lipid metabolism machinery including the delta(14)-sterol reductase, kinesin-like proteins (KIF-22/20A) and the actin-related protein 2/3 complex. Independent microscopy-based validation experiments confirmed cell-type specific morphometric responses. In conclusion, we established a robust workflow enabling the description of the adaptive potential of ovarian cancer cells to physical and chemical stressors typical for the abdominal cavity and supporting the identification of novel molecular mechanisms sustaining tumor plasticity and pharmacologic resistance.

RAI14 Regulated by circNFATC3/miR-23b-3p axis Facilitates Cell Growth and Invasion in Gastric Cancer

Circular RNAs (circRNAs) have been proved to act crucial roles in multiple malignancies including gastric cancer (GC). Retinoic acid induced 14 (RAI14) acts as an oncogene in human cancers, but the underlying mechanisms by which RAI14 is regulated by circRNA/miRNA axis remain elusive. The clinical value of RAI14, miR-23b-3p and circNFATC3 was estimated by The Cancer Genome Atlas and fluorescence in situ hybridization. The interplay between miR-23b-3p and RAI14 or circNFATC3 was determined by qRT-PCR, Western blot, luciferase gene report and RIP assays. Biological function assays and a subcutaneous xenograft model were executed to unveil the role of circNFATC3/miR-23b-3p/RAI14 axis in GC cells. As a consequence, upregulation of RAI14 and circNFATC3 or downregulation of miR-23b-3p was associated with poor prognosis in patients with GC. Restored miR-23b-3p depressed cell proliferation, colony formation, and cell invasion by targeting RAI14, whereas RAI14 facilitated cell progression and reversed the anti-tumor effects of miR-23b-3p in GC cells. Then, circNFATC3 had a co-localization with miR-23b-3p in the cytoplasm in GC tissue cells and could act as a sponge of miR-23b-3p in GC cell line. Silencing of circNFATC3 inhibited cell growth and in vivo tumorigenesis by upregulating miR-23b-3p and downregulating RAI14. In conclusion, our findings indicated that RAI14 facilitated cell growth and invasion and was regulated by circNFATC3/miR-23b-3p axis in GC.

RAI14 Is a Prognostic Biomarker and Correlated With Immune Cell Infiltrates in Gastric Cancer

OBJECTIVE

To analyze the expression and clinical significance of retinoic acid-induced protein 14 (RAI14) in gastric cancer and its relationship with immune cell infiltration by mining databases such as Oncomine, TIMER, UALCAN, and Kaplan Meier Plotter.

METHODS

RAI14 expression in various cancer types was analyzed using the Oncomine and TIMER databases. We used the Kaplan-Meier Plotter and UALCAN databases to evaluate the impact of RAI14 on clinicopathological parameters in gastric cancer. The correlation between RAI14 expression and immune cell invasion was studied using TIMER. TIMER was also used to analyze the correlation between RAI14 expression and marker levels of tumor-infiltrating immune cells.

RESULTS

High RAI14 expression in gastric cancer was significantly associated with poor overall survival (OS; hazard ratio [HR] = 1.82, 95% confidence interval [CI] = 1.53-2.15, P < 0.001) and poor progression-free survival (PFS; HR = 2.16, 95% CI = 1.77-2.65, P < 0.001). Furthermore, high RAI14 expression was significantly associated with poor prognosis of patients with stage 2-4 gastric cancer, but not with OS and PFS of stage 1 patients (OS P = 0.17; PFS P = 0.09), and patients with stage N0 PFS had nothing to do (PFS P = 0.238). RAI14 expression was positively correlated with the infiltration levels of monocytes, tumor-associated macrophages, macrophages, neutrophils, and Treg cells in gastric cancer. Besides, RAI14 expression was closely related to various marker genes in immune cells.

CONCLUSION

RAI14 is highly expressed in gastric cancer, and its expression level is correlated with the prognosis of patients with gastric cancer. RAI14 plays also an important role in the recruitment and regulation of infiltrating immune cells and is, thus, expected to become a target for the optimal treatment of gastric cancer.

RAI14 silencing suppresses progression of esophageal cancer via the STAT3 pathway

Esophageal cancer (EC) is an aggressive malignancy that has an unclear molecular pathogenesis. Although retinoic acid induced 14 (RAI14) is involved in various cancer processes, the relationship between EC and RAI14 has not been elucidated. Our study reported the oncogenic function of RAI14 and its underlying mechanisms in EC. The Cancer Genome Atlas (TCGA) database revealed that RAI14 was upregulated in EC, and this upregulation correlated with T stage, histologic grade, and poor clinical prognosis. RAI14 was evaluated in EC cell lines, and the overexpression of RAI14 promoted cell proliferation, migration, and invasion in vitro. Conversely, RAI14 knockdown induced apoptosis and cell cycle arrest. RAI14 activated STAT3, upregulated Mcl-1 and cyclin D1, and inhibited cleaved caspase-3. Inhibition of STAT3 restored the oncogenic effect of RAI14, and RAI14 silencing restrained tumor growth and the protein level of Ki67 in vivo. Our results suggest that RAI14 regulates the STAT3 pathway and acts as an oncogene during EC progression.