The novel prognostic marker SPOCK2 regulates tumour progression in melanoma.

Secreted protein acidic and cysteine rich/osteonectin, cwcv and kazal-like domain proteoglycan 2 (SPOCK2) is a protein that regulates cell differentiation and growth. Recent studies have reported that SPOCK2 plays important roles in the progression of various human cancers; however, the role of SPOCK2 in melanoma remains unknown. Therefore, this study investigated the roles of SPOCK2 and the related mechanisms in melanoma progression. To evaluate the clinical significance of SPOCK2 expression in patients with melanoma, we analysed the association between SPOCK2 expression and its prognostic value for patients with melanoma using systematic multiomic analysis. Subsequently, to investigate the roles of Spock2 in melanoma progression in vitro and in vivo, we knocked down Spock2 in the B16F10 melanoma cell line. High SPOCK2 levels were positively associated with good prognosis and long survival rate of patients with melanoma. Spock2 knockdown promoted melanoma cell proliferation by inducing the cell cycle and inhibiting apoptosis. Moreover, Spock2 downregulation significantly increased cell migration and invasion by upregulating MMP2 and MT1-MMP. The increased cell proliferation and migration were inhibited by MAPK inhibitor, and ERK phosphorylation was considerably enhanced in Spock2 knockdown cells. Therefore, Spock2 could function as a tumour suppressor gene to regulate melanoma progression by regulating the MAPK/ERK signalling pathway. Additionally, Spock2 knockdown cell injection induced considerable tumour growth and lung metastasis in C57BL6 mice compared to that in the control group. Our findings suggest that SPOCK2 plays crucial roles in malignant progression of melanoma and functions as a novel therapeutic target of melanoma.

Systematic Multiomic Analysis of PKHD1L1 Gene Expression and Its Role as a Predicting Biomarker for Immune Cell Infiltration in Skin Cutaneous Melanoma and Lung Adenocarcinoma.

The identification of genetic factors that regulate the cancer immune microenvironment is important for understanding the mechanism of tumor progression and establishing an effective treatment strategy. Polycystic kidney and hepatic disease 1-like protein 1 (PKHD1L1) is a large transmembrane protein that is highly expressed in immune cells; however, its association with tumor progression remains unclear. Here, we systematically analyzed the clinical relevance of PKHD1L1 in the tumor microenvironment in multiple cancer types using various bioinformatic tools. We found that the PKHD1L1 mRNA expression levels were significantly lower in skin cutaneous melanoma (SKCM) and lung adenocarcinoma (LUAD) than in normal tissues. The decreased expression of PKHD1L1 was significantly associated with unfavorable overall survival (OS) in SKCM and LUAD. Additionally, PKHD1L1 expression was positively correlated with the levels of infiltrating B cells, cluster of differentiation (CD)-8+ T cells, and natural killer (NK) cells, suggesting that the infiltration of immune cells could be associated with a good prognosis due to increased PKHD1L1 expression. Gene ontology (GO) analysis also revealed the relationship between PKHD1L1-co-altered genes and the activation of lymphocytes, including B and T cells. Collectively, this study shows that PKHD1L1 expression is positively correlated with a good prognosis via the induction of immune infiltration, suggesting that PKHD1L1 has potential prognostic value in SKCM and LUAD.

The molecular dynamics of subdistal appendages in multi-ciliated cells.

The motile cilia of ependymal cells coordinate their beats to facilitate a forceful and directed flow of cerebrospinal fluid (CSF). Each cilium originates from a basal body with a basal foot protruding from one side. A uniform alignment of these basal feet is crucial for the coordination of ciliary beating. The process by which the basal foot originates from subdistal appendages of the basal body, however, is unresolved. Here, we show FGFR1 Oncogene Partner (FOP) is a useful marker for delineating the transformation of a circular, unpolarized subdistal appendage into a polarized structure with a basal foot. Ankyrin repeat and SAM domain-containing protein 1A (ANKS1A) interacts with FOP to assemble region I of the basal foot. Importantly, disruption of ANKS1A reduces the size of region I. This produces an unstable basal foot, which disrupts rotational polarity and the coordinated beating of cilia in young adult mice. ANKS1A deficiency also leads to severe degeneration of the basal foot in aged mice and the detachment of cilia from their basal bodies. This role of ANKS1A in the polarization of the basal foot is evolutionarily conserved in vertebrates. Thus, ANKS1A regulates FOP to build and maintain the polarity of subdistal appendages.

Anks1a regulates COPII-mediated anterograde transport of receptor tyrosine kinases critical for tumorigenesis.

ErbB2 signalling, which is amplified by EphA2 binding, is an important therapeutic target for breast cancer. Despite the importance of the EphA2/ErbB2 complex in promoting breast tumorigenesis, the mechanism by which these receptor tyrosine kinases (RTKs) are exported from the endoplasmic reticulum (ER) remains poorly understood. Here we report that the PTB adaptor Anks1a is specifically localized to the ER on its own serine phosphorylation. Once there, Anks1a acts as an important regulator of COPII-mediated EphA2 ER export. The Anks1a ankyrin repeat domain binds EphA2 and causes it to accumulate at sites of ER exit. Simultaneously, the Anks1a PTB domain binds Sec23. This induces internalization of EphA2 via COPII vesicles, while Anks1a remains behind on the ER membrane. EphA2 also binds ErbB2 in the ER and seems to load ErbB2 into growing COPII carriers. Together, our study reveals a novel mechanism that regulates the loading of RTKs into COPII vesicles.

EphrinA5-EphA7 complex induces apoptotic cell death via TNFR1.

A previous study showed that the EphA7 receptor regulates apoptotic cell death during early brain development. In this study, we provide evidence that the EphA7 receptor interacts with death receptors such as tumor necrosis factor receptor 1 (TNFR1) to decrease cell viability. We showed that ephrinA5 stimulates EphA7 to activate the TNFR1-mediated apoptotic signaling pathway. In addition, a pull-down assay using biotinylated ephrinA5-Fc revealed that ephrinA5-EphA7 complexes recruit TNFR1 to form a multi-protein complex. Immunocytochemical staining analysis showed that EphA7 was co-localized with TNFR1 on the cell surface when cells were incubated with ephrinA5 at low temperatures. Finally, both the internalization motif and death domain of TNFR1 was important for interacting with an intracytoplasmic region of EphA7; this interaction was essential for inducing the apoptotic signaling cascade. This result suggests that a distinct multi-protein complex comprising ephrinA5, EphA7, and TNFR1 may constitute a platform for inducing caspase-dependent apoptotic cell death.

A gene trap knockout of the Tiam-1 protein results in malformation of the early embryonic brain.

Tiam-1 has been implicated in the development of the central nervous system. However, the in vivo function of Tiam-1 has not been fully determined in the developing mouse brain. In this study, we generated Tiam-1 knockout mice using a Tiam-1 gene-trapped embryonic stem cell line. Insertion of a gene trap vector into a genomic site downstream of exon 5 resulted in a mutant allele encoding a truncated protein fused with the ß-geo LacZ gene. Primary mouse embryonic fibroblasts lacking Tiam-1 revealed a significant decrease in Rac activity and cell proliferation. In addition, whole-mount embryonic LacZ expression analysis demonstrated that Tiam-1 is specifically expressed in regions of the developing brain, such as the caudal telencephalon and rostral diencephalon. More importantly, mouse embryos deficient in Tiam-1 gene expression displayed a severe defect in embryonic brain development, including neural tube closure defects or a dramatic decrease in brain size. These findings suggest that embryonic Tiam-1 expression plays a critical role during early brain development in mice.

The SAM domains of Anks family proteins are critically involved in modulating the degradation of EphA receptors.

We recently reported that the phosphotyrosine-binding (PTB) domain of Anks family proteins binds to EphA8, thereby positively regulating EphA8-mediated signaling pathways. In the current study, we identified a potential role for the SAM domains of Anks family proteins in EphA signaling. We found that SAM domains of Anks family proteins directly bind to ubiquitin, suggesting that Anks proteins regulate the degradation of ubiquitinated EphA receptors. Consistent with the role of Cbl ubiquitin ligases in the degradation of Eph receptors, our results revealed that the ubiquitin ligase c-Cbl induced the ubiquitination and degradation of EphA8 upon ligand binding. Ubiquitinated EphA8 also bound to the SAM domains of Odin, a member of the Anks family proteins. More importantly, the overexpression of wild-type Odin protected EphA8 and EphA2 from undergoing degradation following ligand stimulation and promoted EphA-mediated inhibition of cell migration. In contrast, a SAM domain deletion mutant of Odin strongly impaired the function of endogenous Odin, suggesting that the mutant functions in a dominant-negative manner. An analysis of Odin-deficient primary embryonic fibroblasts indicated that Odin levels play a critical role in regulating the stability of EphA2 in response to ligand stimulation. Taken together, our studies suggest that the SAM domains of Anks family proteins play a pivotal role in enhancing the stability of EphA receptors by modulating the ubiquitination process.