Special AT-rich sequence-binding protein 2 suppresses invadopodia formation in HCT116 cells via palladin inhibition

SATB2 induction of a neural crest mesenchyme-like program drives melanoma invasion and drug resistance

Recent genomic and scRNA-seq analyses of melanoma demonstrated a lack of recurrent genetic drivers of metastasis, while identifying common transcriptional states correlating with invasion or drug resistance. To test whether transcriptional adaptation can drive melanoma progression, we made use of a zebrafish mitfa:BRAFV600E;tp53-/- model, in which malignant progression is characterized by minimal genetic evolution. We undertook an overexpression-screen of 80 epigenetic/transcriptional regulators and found neural crest-mesenchyme developmental regulator SATB2 to accelerate aggressive melanoma development. Its overexpression induces invadopodia formation and invasion in zebrafish tumors and human melanoma cell lines. SATB2 binds and activates neural crest-regulators, including pdgfab and snai2. The transcriptional program induced by SATB2 overlaps with known MITF^lowAXL^high and AQP1⁺NGFR1^high drug-resistant states and functionally drives enhanced tumor propagation and resistance to Vemurafenib in vivo. In summary, we show that melanoma transcriptional rewiring by SATB2 to a neural crest mesenchyme-like program can drive invasion and drug resistance in autochthonous tumors.

SP3 is associated with migration, invasion, and Akt/PKB signalling in MDA-MB-231 breast cancer cells

Specificity proteins (SPs) have pro-oncogenic functions in cancer cells, ranging from cancer cell proliferation, migration, invasion, and angiogenesis. There is strong evidence that several antineoplastic drugs target depletion of SP proteins via different pathways. However, the mode of action of SP3 and the underlying consequences of its depletion are not well understood. Here, we demonstrate that SP3 is overexpressed in invasive breast cancer cells vs normal counterparts. The gene expression analysis from The Cancer Genome Atlas datasets indicated that SP3 is strongly correlated with Akt signalling-related proteins, G protein subunit alpha 13, and RAB33B (RAB33B, member RAS oncogene family). RNA interference of SP3 decreased active phosphorylation of Akt at serine and threonine sites. These findings indicate that SP3 exhibits a pro-oncogenic function, which clearly fits the description of an nononcogene addiction gene. Future analyses are prompted to uncover the SP3 gene regulation function and to reveal downstream targets of SP3 in breast cancer.

Dehydroandrographolide Inhibits Osteosarcoma Cell Growth and Metastasis by Targeting SATB2-mediated EMT

BACKGROUND

The 12-hydroxy-14-dehydroandrographolide (DP) is a predominant component of the traditional herbal medicine Andrographis paniculata (Burm. f.) Nees (Acanthaceae). Recent studies have shown that DP exhibits potent anti-cancer effects against oral and colon cancer cells.

OBJECTIVE

This investigation examined the potential effects of DP against osteosarcoma cell.

METHODS

A cell analyzer was used to measure cell viability. The cell growth and proliferation were performed by Flow cytometry and BrdU incorporation assay. The cell migration and invasion were determined by wound healing and transwell assay. The expression of EMT related proteins was examined by Western blot analysis.

RESULTS

In this study, we found that DP treatment repressed osteosarcoma (OS) cell growth in a dose-dependent manner. DP treatment significantly inhibited OS cell proliferation by arresting the cell cycle at G2/M phase. In addition, DP treatment effectively inhibited the migration and invasion abilities of OS cells through wound healing and Transwell tests. Mechanistic studies revealed that DP treatment effectively rescued the epithelialmesenchymal transition (EMT), while forced expression of SATB2 in OS cells markedly reversed the pharmacological effect of DP on EMT.

CONCLUSION

Our data demonstrated that DP repressed OS cell growth through inhibition of proliferation and cell cycle arrest; DP also inhibited metastatic capability of OS cells through a reversal of EMT by targeting SATB2. These findings demonstrate DP's potential as a therapeutic drug for OS treatment.

Metastatic colorectal carcinomas with high SATB2 expression are associated with better prognosis and response to chemotherapy: a population-based Scandinavian study

Background: Survival and response to therapy in patients with metastatic colorectal cancer (mCRC) are very heterogeneous. There is an unmet need for better markers of prognosis and treatment benefit for mCRC patients. The homeobox 2 gene SATB2 has a highly specific expression in colorectal tissue and is associated with better prognosis in non-metastatic CRC.Material and methods: A population-based cohort of 798 mCRC patients was analysed. From primary tumour material, protein expression was assessed by immunohistochemistry. BRAF and KRAS mutation status was also determined. Associations with clinicopathological data, overall and progression-free survival and response to first-line chemotherapy were analysed.Results: Tumour tissue and clinical data were available from 467 patients. SATB2 was strongly expressed in 58% of cases, significantly more in left-sided, low-grade and wild-type BRAF tumours. Patients with high SATB2 tumours had longer overall survival compared with low SATB2 tumours (median 13 vs 8 months respectively, p < .001). Chemotherapy was given to 282 patients (63%). Patients with high SATB2 tumours had longer OS (median 22 vs 15 months respectively, p = .001) and more often responded to chemotherapy than those with low SATB2 (objective response 43% vs 29%, p = .02; clinical response 83% vs 67%, p = .004). Progression-free survival on first-line irinotecan chemotherapy was longer in high SATB2 cases (median 8 vs 4 months respectively, p = .019). Patients with both low SATB2 expression and mutated BRAF (n = 69) had particularly poor survival compared to the rest (median 8 and 12 months respectively, p = .001). In multivariable analysis, the SATB2 findings were independent of known clinicopathological prognostic markers, including BRAF mutation status.Conclusion: Patients with mCRC expressing high level of SATB2 have better prognosis and response to chemotherapy than those with low SATB2 expression. Patients with both low SATB2 expression and mutated BRAF had particularly poor prognosis and could thus benefit from more aggressive therapies.

LncRNA SATB2-AS1 inhibits tumor metastasis and affects the tumor immune cell microenvironment in colorectal cancer by regulating SATB2

Background

Emerging studies suggest that long non-coding RNAs (lncRNAs) play crucial roles in colorectal cancer (CRC). Here, we report a lncRNA, SATB2-AS1, which is specifically expressed in colorectal tissue and is significantly reduced in CRC. We systematically elucidated its functions and possible molecular mechanisms in CRC.

Methods

LncRNA expression in CRC was analyzed by RNA-sequencing and RNA microarrays. The expression level of SATB2-AS1 in tissues was determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and in situ hybridization (ISH). The functional role of SATB2-AS1 in CRC was investigated by a series of in vivo and in vitro assays. RNA pull-down, RNA immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP), chromatin isolation by RNA purification (ChIRP), Bisulfite Sequencing PCR (BSP) and bioinformatics analysis were utilized to explore the potential mechanisms of SATB2-AS1.

Results

SATB2-AS1 is specifically expressed in colorectal tissues and downregulated in CRC. Survival analysis indicates that decreased SATB2-AS1 expression is associated with poor survival. Functional experiments and bioinformatics analysis revealed that SATB2-AS1 inhibits CRC cell metastasis and regulates TH1-type chemokines expression and immune cell density in CRC. Mechanistically, SATB2-AS1 directly binds to WDR5 and GADD45A, cis-activating SATB2 (Special AT-rich binding protein 2) transcription via mediating histone H3 lysine 4 tri-methylation (H3K4me3) deposition and DNA demethylation of the promoter region of SATB2.

Conclusions

This study reveals the functions of SATB2-AS1 in CRC tumorigenesis and progression, suggesting new biomarkers and therapeutic targets in CRC.

Electronic supplementary material

The online version of this article (10.1186/s12943-019-1063-6) contains supplementary material, which is available to authorized users.

PI3Kβ links integrin activation and PI(3,4)P2 production during invadopodial maturation

The invasion of tumor cells from the primary tumor is mediated by invadopodia, actin-rich protrusive organelles that secrete matrix metalloproteases and degrade the extracellular matrix. This coupling between protrusive activity and matrix degradation facilitates tumor invasion. We previously reported that the PI3Kβ isoform of PI 3-kinase, which is regulated by both receptor tyrosine kinases and G protein-coupled receptors, is required for invasion and gelatin degradation in breast cancer cells. We have now defined the mechanism by which PI3Kβ regulates invadopodia. We find that PI3Kβ is specifically activated downstream from integrins, and is required for integrin-stimulated spreading and haptotaxis as well as integrin-stimulated invadopodia formation. Surprisingly, these integrin-stimulated and PI3Kβ-dependent responses require the production of PI(3,4)P2 by the phosphoinositide 5'-phosphatase SHIP2. Thus, integrin activation of PI3Kβ is coupled to the SHIP2-dependent production of PI(3,4)P2, which regulates the recruitment of PH domain-containing scaffolds such as lamellipodin to invadopodia. These findings provide novel mechanistic insight into the role of PI3Kβ in the regulation of invadopodia in breast cancer cells.

Integrins: Moonlighting Proteins in Invadosome Formation

Invadopodia are actin-rich protrusions developed by transformed cells in 2D/3D environments that are implicated in extracellular matrix (ECM) remodeling and degradation. These structures have an undoubted association with cancer invasion and metastasis because invadopodium formation in vivo is a key step for intra/extravasation of tumor cells. Invadopodia are closely related to other actin-rich structures known as podosomes, which are typical structures of normal cells necessary for different physiological processes during development and organogenesis. Invadopodia and podosomes are included in the general term 'invadosomes,' as they both appear as actin puncta on plasma membranes next to extracellular matrix metalloproteinases, although organization, regulation, and function are slightly different. Integrins are transmembrane proteins implicated in cell-cell and cell-matrix interactions and other important processes such as molecular signaling, mechano-transduction, and cell functions, e.g., adhesion, migration, or invasion. It is noteworthy that integrin expression is altered in many tumors, and other pathologies such as cardiovascular or immune dysfunctions. Over the last few years, growing evidence has suggested a role of integrins in the formation of invadopodia. However, their implication in invadopodia formation and adhesion to the ECM is still not well known. This review focuses on the role of integrins in invadopodium formation and provides a general overview of the involvement of these proteins in the mechanisms of metastasis, taking into account classic research through to the latest and most advanced work in the field.

Ubiquitination: Friend and foe in cancer

Dynamic modulation and posttranslational modification of proteins are tightly controlled biological processes that occur in response to physiological cues. One such dynamic modulation is ubiquitination, which marks proteins for degradation via the proteasome, altering their localization, affecting their activity, and promoting or interfering with protein interactions. Hence, ubiquitination is crucial for a plethora of physiological processes, including cell survival, differentiation and innate and adaptive immunity. Similar to kinases, components of the ubiquitination system are often deregulated, leading to a variety of diseases, such as cancer and neurodegenerative disorders. In a context-dependent manner, ubiquitination can regulate both tumor-suppressing and tumor-promoting pathways in cancer. This review outlines how components of the ubiquitination systems (e.g. E3 ligases and deubiquitinases) act as oncogenes or tumor suppressors according to the nature of their substrates. Furthermore, I interrogate how the current knowledge of the differential roles of ubiquitination in cancer lead to technical advances to inhibit or reactivate the components of the ubiquitination system accordingly.

SATB2 targeted by methylated miR-34c-5p suppresses proliferation and metastasis attenuating the epithelial-mesenchymal transition in colorectal cancer

OBJECTIVES

SATB2 has been shown to be markedly reduced in colorectal cancer (CRC) tissues relative to paired normal controls; however, the mechanism behind remains not well understood. To investigate why SATB2 was down-regulated in CRC, we attempted to analyse it from the angle of miRNA-mRNA modulation.

MATERIALS AND METHODS

SATB2 expression was detected in CRC tissues using immunohistochemistry and verified using real-time PCR on mRNA level, followed by analysis of clinicopathological significance of its expression. Metastatic variation of CRC cells was evaluated both in vivo and in vitro. To find out the potential miRNA that directly regulate the SATB2, luciferase reporter assay was performed following the bioinformatic prediction.

RESULTS

SATB2 was confirmed to be closely linked with the metastasis and shorter overall survival of CRC in our own cases. Silencing of SATB2 was shown to be able to promote the metastatic ability of CRC cells in vivo, enhancing the epithelial-mesenchymal transition (EMT). Mechanistically, miR-34c-5p was identified to be a novel miRNA that can directly modulate the SATB2. It turned out that the promoter of miR-34c-5p was methylated, which leads to the repression of miR-34c-5p in CRC. Treatment with 5-Aza-dC can reasonably and significantly restore the level of miR-34c-5p in CRC cells relative to control, thereby down-regulating the SATB2.

CONCLUSIONS

Together, our study revealed that SATB2 targeted by methylated miR-34c-5p can suppress the metastasis, weakening the EMT in CRC.

HOXD8 exerts a tumor-suppressing role in colorectal cancer as an apoptotic inducer

Homeobox (HOX) genes are conserved transcription factors which determine the anterior-posterior body axis patterning. HOXD8 is a member of HOX genes deregulated in several tumors such as lung carcinoma, neuroblastoma, glioma and colorectal cancer (CRC) in a context-dependent manner. In CRC, HOXD8 is downregulated in cancer tissues and metastatic foci as compared to normal tissues. Whether HOXD8 acts as a tumor suppressor of malignant progression and metastasis is still unclear. Also, the underlying mechanism of its function including the downstream targets is totally unknown. Here, we clarified the lower expression of HOXD8 in clinical colorectal cancer vs. normal colon tissues. Also, we showed that stable expression of HOXD8 in colorectal cancer cells significantly reduced the cell proliferation, anchorage-independent growth and invasion. Further, using The Cancer Genome Atlas (TCGA), we identified the genes associated with HOXD8 in order to demonstrate its function as a suppressor or a promoter of colorectal carcinoma. Among inversely related genes, apoptotic inhibitors like STK38 kinase and MYC were shown to be negatively associated with HOXD8. We demonstrated the ability of HOXD8 to upregulate executioner caspases 6 & 7 and cleaved PARP, thus inducing the apoptotic events in colorectal cancer cells.

SATB1 and SATB2 play opposing roles in c-Myc expression and progression of colorectal cancer

Special AT-rich sequence-binding protein 1 and 2 (SATB1/2) are nuclear matrix-associated proteins involved in chromatin remodeling and regulation of gene expression. SATB2 acts as a tumor suppressor in laryngeal squamous cell carcinoma and colon cancer, whereas SATB1 promotes the progression of numerous types of cancers. In this study, we examined the effects of SATB1 and SATB2 on the malignant characteristics of colorectal cancer cells. SATB1 and SATB2 expression were negatively correlated in colorectal cancer specimens. SATB1 expression was increased, whereas SATB2 expression was reduced, in colorectal cancer tissues compared to control tissues. Exogenous expression of SATB2 in colorectal cancer cells suppressed cell proliferation, colony formation and tumor proliferation in mice. c-Myc was reduced by SATB2 expression, and exogenous expression of c-Myc in SATB2-expressing cells restored proliferation, colony formation and in vivo tumor growth of colorectal cancer cells. We also showed that c-Myc reduction by SATB2 was mediated by the inactivation of ERK5. In contrast, SATB1 promoted c-Myc expression. The expression of SATB1 in colorectal cancer tissues was positively correlated with c-Myc expression, and SATB1 knockdown reduced c-Myc expression in colorectal cancer cells. Finally, we showed that SATB1 knockdown in colorectal cancer cells suppressed cell proliferation, colony formation and cell invasion. Our results reveal interesting features of how the structural homologs SATB1 and SATB2 exert opposing functions in colorectal tumorigenesis.