Depletion of p42.3 gene inhibits proliferation and invasion in melanoma cells

The Function and Regulation of SAPCD2 in Physiological and Oncogenic Processes

The Suppressor APC Domain Containing 2 (SAPCD2) gene, also known by its aliases p42.3 and c9orf140, encodes a protein with an approximate molecular weight of 42.3 kDa. It was initially recognized as a cell cycle-associated protein involved in mitotic progression. Since the initial discovery of this gene, emerging evidence has suggested that its functions extend beyond that of regulating cell cycle progression to include modulation of planar polarization of cell progenitors and determination of cell fate throughout embryonic development. The underlying mechanisms driving such functions have been partially elucidated. However, the detailed mechanisms of action remain to be further characterized. The expression level of SAPCD2 is high throughout embryogenesis but is generally absent in healthy postnatal tissues, with restored expression in adult tissues being associated with various disease states. The pathological consequences of its aberrant expression have been investigated, most notably in the development of several types of cancers. The role of SAPCD2 in tumorigenesis has been supported by in vitro, in vivo, and retrospective clinical investigations and the mechanisms underlying its oncogenic function have been partially revealed. The potential of SAPCD2 as a diagnostic marker and therapeutic target of cancers have also been explored and have shown great promise. However, many questions pertaining to its oncogenic mechanisms as well as its value as a diagnostic marker and therapeutic target remain to be answered. In addition to its function as an oncogene, an involvement of SAPCD2 in other pathological processes such as inflammation has also been implicated and provides additional directions that warrant future investigation. This article reviews the current understanding of the normal cellular functions of SAPCD2 and the relevance of SAPCD2 in disease development with a primary focus on tumorigenesis. The mechanisms that regulate p43.2 expression, including the potential role of microRNAs in regulating its expression, are also reviewed. To the best of our knowledge, we are the first to comprehensively review the published findings regarding the physiological and pathological functions of this gene.

SAPCD2 promotes neuroblastoma progression by altering the subcellular distribution of E2F7

Recent studies uncovered the emerging roles of SAPCD2 (suppressor anaphase-promoting complex domain containing 2) in several types of human cancer. However, the functions and underlying mechanisms of SAPCD2 in the progression of neuroblastoma (NB) remain elusive. Herein, through integrative analysis of public datasets and regulatory network of GSK-J4, a small-molecule drug with anti-NB activity, we identified SAPCD2 as an appealing target with a high connection to poor prognosis in NB. SAPCD2 promoted NB progression in vitro and in vivo. Mechanistically, SAPCD2 could directly bind to cytoplasmic E2F7 but not E2F1, alter the subcellular distribution of E2F7 and regulate E2F activity. Among the E2F family members, the roles of E2F7 in NB are poorly understood. We found that an increasing level of nuclear E2F7 was induced by SAPCD2 knockdown, thereby affecting the expression of genes involved in the cell cycle and chromosome instability. In addition, Selinexor (KTP-330), a clinically available inhibitor of exportin 1 (XPO1), could induce nuclear accumulation of E2F7 and suppress the growth of NB. Overall, our studies suggested a previously unrecognized role of SAPCD2 in the E2F signaling pathway and a potential therapeutic approach for NB, as well as clues for understanding the differences in subcellular distribution of E2F1 and E2F7 during their nucleocytoplasmic shuttling.

Silencing SAPCD2 Represses Proliferation and Lung Metastasis of Fibrosarcoma by Activating Hippo Signaling Pathway

The primary problem associated with fibrosarcoma is its high potential to metastasize to the lung. Aberrant expression of SAPCD2 has been widely reported to be implicated in the progression and metastasis in multiple cancer types. However, the clinical significance and biological roles of SAPCD2 in fibrosarcoma remain unknown. Here, we reported that SAPCD2 expression was markedly elevated in fibrosarcoma tissues, and its expression was differentially upregulated in fibrosarcoma cell lines compared with that in several primary fibroblast cell lines. Kaplan-Meier survival analysis revealed that SAPCD2 overexpression was significantly correlated with early progression and metastasis, and poor prognosis in fibrosarcoma patients. Our results further showed that silencing SAPCD2 inhibited the proliferation and increased the apoptosis of fibrosarcoma cells in vitro. Importantly, silencing SAPCD2 repressed lung metastasis of fibrosarcoma cells in vivo. Mechanistic investigation further demonstrated that silencing SAPCD2 inhibited the proliferation and lung metastasis of fibrosarcoma cells by activating the Hippo signaling pathway, as evidenced by the finding that constitutively active YAP1, YAP1-S127A, significantly reversed the inhibitory effect of SAPCD2 downregulation on the colony formation and anchorage-independent growth capabilities of fibrosarcoma cells, as well as the stimulatory effect on the apoptotic ratio of fibrosarcoma cells. In conclusion, SAPCD2 promotes the proliferation and lung metastasis of fibrosarcoma cells by regulating the activity of Hippo signaling, and this mechanism represents a potential therapeutic target for the treatment of lung metastatic fibrosarcoma.

Expression of p42.3 in non-small cell lung cancer

Background

Lung cancer is the most malignant tumor with the highest morbidity and mortality. This study aimed to investigate the role of the expression and the significance of the p42.3 gene in non-small cell lung cancer (NSCLC).

Methods

Lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) were analyzed based on the biological information data of The Cancer Genome Atlas (TCGA). Furthermore, 142 postoperative tumor tissue and normal tissue samples (70 cases of LUAD and 72 cases of LUSC) from NSCLC patients admitted to our hospital from 2005 to 2009 were retrospectively collected. Paraffin-embedded tissues were used to make the tissue microarrays (TMA), and the expression of the p42.3 protein was detected by immunohistochemical staining.

Results

The expression of p42.3 in both LUAD and LUSC was significantly upregulated (P<0.01) compared with the normal lung tissues. The p42.3 expression was significantly higher than that of LUAD (P<0.01) in the LUSC group. LUSC had a lower level of p42.3 DNA methylation and a higher level of p42.3 DNA amplification than LUAD. The expression rate of p42.3 protein decreased in patients 70 years or older (P=0.029). High expression of the p42.3 protein was an independent factor for worse pathological differentiation (P=0.043).

Conclusions

Both genetic and epigenetic alterations contributed to dysregulated p42.3 in NSCLC. Despite the temporary absence of TCGA-LUSC (TCGA data on LUSC) survival information, we observed that the up-regulated expression of p42.3 in LUSC was significantly higher than that in LUAD by analyzing the public database and reviewing the real-world data. Furthermore, a high expression of p42.3 protein was significantly correlated with poor differentiation of tumor tissues. Therefore, the prognostic value of p42.3 in LUSC deserves further study.

Overexpression of SAPCD2 correlates with proliferation and invasion of colorectal carcinoma cells

Background

Suppressor anaphase-promoting complex domain containing 2 (SAPCD2) is a novel gene playing important roles in the initiation, invasion, and metastasis of several malignancies. However, its role in colorectal carcinoma (CRC) still remains unclear.

Method

In this study, we investigated the expression and biological function of SAPCD2 in CRC. Immunohistochemistry (IHC) for SAPCD2 was performed in 410 pairs of CRC specimens and corresponding normal epithelial tissues, and in 50 adenoma tissues. Clinical pathological factors were analyzed in relation to the expression of SAPCD2. The biological functions of SAPCD2 in CRC cells and its effect on cell cycle were investigated in vitro and in vivo through gain/loss-of-function approaches.

Results

IHC showed that SAPCD2 expression was significantly higher in CRC tissues compared to adenoma and normal epithelium tissues and was correlated with tumor location (p = 0.018). SAPCD2 significantly promoted cell proliferation, migration, and invasion both in vitro and in vivo (p < 0.05). In addition, SAPCD2 knockdown in CRC cells was associated with reduced G₁/S transition, while overexpression caused G₂/M phase arrest (p < 0.05).

Conclusions

In sum, SAPCD2 is overexpressed in CRC tissues and plays a critical role in CRC progression. Therefore, it might represent a promising therapeutic target for CRC treatment.

A microcarrier-based spheroid 3D invasion assay to monitor dynamic cell movement in extracellular matrix

Background

Cell invasion through extracellular matrix (ECM) is a critical step in tumor metastasis. To study cell invasion in vitro, the internal microenvironment can be simulated via the application of 3D models.

Results

This study presents a method for 3D invasion examination using microcarrier-based spheroids. Cell invasiveness can be evaluated by quantifying cell dispersion in matrices or tracking cell movement through time-lapse imaging. It allows measuring of cell invasion and monitoring of dynamic cell behavior in three dimensions. Here we show different invasive capacities of several cell types using this method. The content and concentration of matrices can influence cell invasion, which should be optimized before large scale experiments. We also introduce further analysis methods of this 3D invasion assay, including manual measurements and homemade semi-automatic quantification. Finally, our results indicate that the position of spheroids in a matrix has a strong impact on cell moving paths, which may be easily overlooked by researchers and may generate false invasion results.

Conclusions

In all, the microcarrier-based spheroids 3D model allows exploration of adherent cell invasion in a fast and highly reproducible way, and provides informative results on dynamic cell behavior in vitro.

Long noncoding RNA PXN-AS1-L promotes the malignancy of nasopharyngeal carcinoma cells via upregulation of SAPCD2

Accumulating evidences highlight the critical roles of long noncoding RNAs (lncRNAs) in a variety of cancers. LncRNA PXN‐AS1‐L was previously shown to exert oncogenic roles in hepatocellular carcinoma. However, the expression, role, and molecular mechanism of PXN‐AS1‐L in nasopharyngeal carcinoma (NPC) malignancy remain unknown. Here, we determined that PXN‐AS1‐L is upregulated in NPC tissues and cell lines. Increased expression of PXN‐AS1‐L predicts worse prognosis of NPC patients. PXN‐AS1‐L overexpression promotes NPC cell proliferation, migration, and invasion in vitro, and NPC tumor growth in vivo. PXN‐AS1‐L silencing suppresses NPC cell proliferation, migration, and invasion in vitro. Mechanistically, PXN‐AS1‐L directly interacts with SAPCD2 mRNA 3′‐untranslated region, prevents the binding of microRNAs‐AGO silencing complex to SAPCD2 mRNA, and upregulates the mRNA and protein level of SAPCD2. SAPCD2 is also increased in NPC tissues. The expression of SAPCD2 is significantly positively associated with that of PXN‐AS1‐L in NPC tissues. Gain‐of‐function and loss‐of‐function experiments demonstrated that SAPCD2 also promotes NPC cell proliferation, migration, and invasion. Furthermore, depletion of SAPCD2 significantly reverses the roles of PXN‐AS1‐L in promoting NPC cell proliferation, migration, and invasion in vitro, and NPC tumor growth in vivo. In conclusion, lncRNA PXN‐AS1‐L is upregulated in NPC and promoted NPC malignancy by upregulating SAPCD2 via direct RNA‐RNA interaction.