Comparison of 18 F-FAPI and 18 F-FDG PET/CT in a Patient With Fibrous Dysplasia.

ABSTRACT: A 16-year-old woman presented with an acute headache on the left side. A head CT scan revealed bone destruction in the skull. Subsequent 18 F-FDG and 18 F-FAPI PET/CT scans were performed within a week. The 18 F-FDG PET/CT indicated mild uptake in the regions of bone destruction, whereas the 18 F-FAPI PET/CT displayed significant tracer accumulation. The patient was ultimately diagnosed with fibrous dysplasia.

Prognosis and immunotherapy response prediction based on M2 macrophage-related genes in colon cancer.

BACKGROUND: M2 macrophage were revealed to play a crucial role in immune evasion and immunotherapies. This study aims to explore the potential significance of M2 macrophage-related genes in colon adenocarcinoma (COAD) by analysizing the transcriptome data in a comprehensive way. METHODS: We collected RNA-sequencing (RNA-seq) data of COAD from The Cancer Genome Atlas (TCGA) and Gene Expression Ominibus (GEO) databases. We calculated the immune infiltration scores of every sample using CIBERSORT algorithm. Through weighted gene co-expression network analysis (WGCNA), we picked out M2 macrophage-related genes. With these genes we screened out prognosis related genes which were utilized to construct a signature to assess the prognosis of patients. To extend the potential application of the signature, we also calculated the correlations with immune infiltration. Finally, we applied techniques such as quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunoblotting (Western Blotting) to validate the RNF32 gene in cellular in vitro assays. RESULTS: Seven M2 macrophage-related genes signature was constructed, which was an excellent prognostic predictor in two independent groups. The high-risk group showed lower immune infiltration and poorer response to immunotherapies than those of the low-risk group. The cell vitro experiments showed that the expression level of RNF32 was upregulated in colon cancer cell lines compared with normal cell lines. Moreover, we found that RNF32 may promote the proliferation, migration and invasion of cancer cells in vitro by inhibiting apoptosis. CONCLUSION: A novel M2 macrophage-related gene signature affects the prognosis and immune characteristics of colon cancer.

Comparative analysis of two timepoints on [18F]FAPI-42 PET/CT in various cancers.

PURPOSE: This study aimed to assess the biodistribution, detection rate, and uptake of the [18F]FAPI-42 at two distinct time intervals. METHODS: This prospective study enrolled 60 consecutive patients (median age 59; range 35-74) referred to [18F]FAPI-42 PET/CT. [18F]FAPI-42 PET/CT was performed early and late timepoint after tracer injection for staging or restaging. Positive lesions specified for anatomic locations (primary or recurrent tumor, LN metastasis and other metastasis) by visual analysis at both timepoints. Semiquantitative analysis of the tracer activity in lesions as well as normal tissues at both time points were measured and compared. In a subgroup analysis, eleven patients underwent 2-[18F]FDG PET/CT within 1 week, the detection rate and uptake of lesion were compared between early [18F]FAPI-42 and 2-[18F]FDG. RESULTS: Uptake of [18F]FAPI-42 in the late timepoint was significantly lower than the early timepoint in most organs (all p < 0.05), except for bone (SUVmean 0.88 vs. 0.85; p = 0.218). Tracer retention at biliary system showed less frequent at early timepoint than late timepoint. A total of 194 lesions were detected in 60 patients. One lesion was only seen at early timepoint but not at late timepoint. Lesions on early [18F]FAPI-42 PET/CT had higher visual score than that of late image(23 vs. 6). The uptake of lesion decreased significantly from early to late timepoint (all p < 0.05). In subgroup analysis, early [18F]FAPI-42 illustrated higher detection rate, visual score, and uptake of lesion than that of 2-[18F]FDG PET/CT. CONCLUSION: Early [18F]FAPI-42 PET/CT provided consistent detection rates and lesion uptake, but less tracer retention in the biliary system compared to late images. Therefore, acquisition at early timepoint could be a feasible strategy for improving acquisition protocols of [18F]FAPI-42 PET/CT. TRIAL REGISTRATION: ChiCTR2200063441. Registered 28 September 2022-Retrospectively registered, https://www.chictr.org.cn/bin/project/edit?pid=149714 .

RPL21 interacts with LAMP3 to promote colorectal cancer invasion and metastasis by regulating focal adhesion formation.

BACKGROUND: Metastasis is the leading cause of death among patients with colorectal cancer (CRC). Therefore, it is important to explore the molecular mechanisms of metastasis to develop effective therapeutic targets for CRC. In the present study, ribosomal protein L21 (RPL21) was considered as being involved in promoting CRC metastasis, yet the underlying mechanism requires further investigation. METHODS: Immunohistochemistry, western blotting, and quantitative reverse transcription polymerase chain reaction were performed to measure the expression of RPL21 and lysosome-associated membrane protein 3 (LAMP3) in CRC tissues and cells. Wound healing, transwell migration, and invasion assays were performed to study the migration and invasion of cultured CRC cells. An orthotopic CRC mouse model was developed to investigate the metastatic ability of CRC. Transcriptome sequencing was conducted to identify the genes related to RPL21. The dual-luciferase reporter gene assay was performed to determine the transcriptional activity of transcription factor EB (TFEB). The GST/His pull-down assay was performed to investigate the specific binding sites of RPL21 and LAMP3. The cell adhesion assay was performed to determine the adhesion ability of CRC cells. Immunofluorescence staining was performed to observe focal adhesions (FAs). RESULTS: RPL21 was highly expressed in CRC, contributing to tumor invasiveness and poor patient prognosis. Functionally, RPL21 promoted the migration and invasion of CRC cells in vitro and tumor metastasis in vivo. Moreover, LAMP3 was identified as being highly related to RPL21 and was essential in promoting the migration and invasion of CRC cells. Mechanistically, RPL21 activated the transcriptional function of TFEB to upregulate LAMP3 expression. RPL21 directly bound to the aa 341-416 domain of LAMP3 via its aa 1-40 and aa 111-160 segments. The combination of RPL21 and LAMP3 enhanced the stability of the RPL21 protein by suppressing the degradation of the ubiquitin-proteasome system. Furthermore, RPL21 and LAMP3 promoted the formation of immature FAs by activating the FAK/paxillin/ERK signaling pathway. CONCLUSIONS: RPL21 promoted invasion and metastasis by regulating FA formation in a LAMP3-dependent manner during CRC progression. The interaction between RPL21 and LAMP3 may function as a potential therapeutic target against CRC.

A new method for predicting the prognosis of colorectal cancer patients through a combination of multiple tumor-associated macrophage markers at the invasive front.

Tumor-associated macrophages (TAMs) are closely related to tumorigenesis and metastasis of multiple cancer types. The infiltration of TAMs is used for predicting the prognosis of cancers, including colorectal cancer (CRC). However, the density and prognostic significance of M1 and M2 TAM phenotypes in the intratumor versus the invasive front (IF) are largely unknown in CRC. In this study, CD68 was selected as a general marker of TAMs, CD11c, NOS2 and CXCL10 as markers for M1 phenotype and CD163, CD206, CD115 as markers for M2 phenotype. Firstly, immunohistochemistry staining and double-labeling immunofluorescence staining showed that M1 molecular markers (NOS2, CXCL10, CD11c) were lowly expressed at both IF and intratumor, while M2 molecular markers (CD163, CD206, CD115) were highly expressed mainly at IF. Moreover, we also demonstrated that three M1 molecular markers including NOS2, CXCL10 and CD11c were correlated to each other. Meanwhile, three M2 molecular markers including CD163, CD206, and CD115 were also correlated to each other. Patients with low expression of three M1 molecular markers (NOS2/CXCL10/CD11c) exhibited low overall survival (OS) rate, whereas patients with high expression of three M2 molecular markers (CD163/CD206/CD115) exhibited low OS rate. We also observed that the prognostic value of treble markers combination (NOS2/CXCL10/CD11c or CD163/CD206/CD115) was superior to that of single marker. Together, our results reveal the combination of treble TAMs markers (NOS2/CXCL10/CD11c or CD163/CD206/CD115) could better evaluate the prognosis of CRC patients, which might be used as a more comprehensive method for predicting the prognosis of CRC patients.

Tumor bud-derived CCL5 recruits fibroblasts and promotes colorectal cancer progression via CCR5-SLC25A24 signaling.

BACKGROUND: Tumor budding is included in the routine diagnosis of colorectal cancer (CRC) and is considered a tumor prognostic factor independent of TNM staging. This study aimed to identify the fibroblast-mediated effect of tumor bud-derived C-C chemokine ligand 5 (CCL5) on the tumor microenvironment (TME). METHODS: Recruitment assays and a human cytokine array were used to detect the main cytokines that CRC tumor buds secrete to recruit fibroblasts. siRNA transfection and inhibitor treatment were used to investigate the role of fibroblast CCL5 receptors in fibroblast recruitment. Subsequently, transcriptome sequencing was performed to explore the molecular changes occurring in fibroblasts upon stimulation with CCL5. Finally, clinical specimens and orthotopic xenograft mouse models were studied to explore the contribution of CCL5 to angiogenesis and collagen synthesis. RESULTS: Hematoxylin-eosin staining and immunochemistry revealed a higher number of fibroblasts at the invasive front of CRC tissue showing tumor budding than at sites without tumor budding. In vitro experiments demonstrated that CCL5 derived from tumor buds could recruit fibroblasts by acting on the CCR5 receptors on fibroblasts. Tumor bud-derived CCL5 could also positively regulate solute carrier family 25 member 24 (SLC25A24) expression in fibroblasts, potentially activating pAkt-pmTOR signaling. Moreover, CCL5 could increase the number of α-SMAhigh CD90high FAPlow fibroblasts and thus promote tumor angiogenesis by enhancing VEGFA expression and making fibroblasts transdifferentiate into vascular endothelial cells. Finally, the results also showed that CCL5 could promote collagen synthesis through fibroblasts, thus contributing to tumor progression. CONCLUSIONS: At the invasive front of CRC, tumor bud-derived CCL5 can recruit fibroblasts via CCR5-SLC25A24 signaling, further promoting angiogenesis and collagen synthesis via recruited fibroblasts, and eventually create a tumor-promoting microenvironment. Therefore, CCL5 may serve as a potential diagnostic marker and therapeutic target for tumor budding in CRC.

CIP4 targeted to recruit GTP-Cdc42 involving in invadopodia formation via NF-κB signaling pathway promotes invasion and metastasis of CRC.

Cdc42-interacting protein 4 (CIP4), a member of the F-BAR family, which plays an important role in regulating cell membrane and actin, has been reported to interact with Cdc42 and be closely associated with tumor invadopodia formation. In this study, we found that CIP4 expression was significantly higher in human CRC tissues and correlated with the CRC infiltrating depth and metastasis, as well as the lower survival rate in patients. In cultured CRC cells, knockdown of CIP4 inhibited cell migration and invasion ability in vitro and tumor metastasis in vivo, while the overexpression of CIP4 promoted invadopodia formation and matrix degradation ability. We then identified GTP-Cdc42 as a directly interactive protein of CIP4, which was upregulated and recruited by CIP4. Furthermore, activated NF-κB signaling pathway was found in CIP4 overexpression of CRC cells contributing to invadopodia formation, while the inhibition of either CIP4 or Cdc42 led to the suppression of the NF-κB pathway and resulted in a decreased quantity of invadopodia. Our findings suggested that CIP4 targets to recruit GTP-Cdc42 and directly combines with it to accelerate invadopodia formation and function by activating NF-κB signaling pathway, thus promoting CRC infiltration and metastasis.

MYH9-dependent polarization of ATG9B promotes colorectal cancer metastasis by accelerating focal adhesion assembly.

Tumour metastasis is a major reason accounting for the poor prognosis of colorectal cancer (CRC), and the discovery of targets in the primary tumours that can predict the risk of CRC metastasis is now urgently needed. In this study, we identified autophagy-related protein 9B (ATG9B) as a key potential target gene for CRC metastasis. High expression of ATG9B in tumour significantly increased the risk of metastasis and poor prognosis of CRC. Mechanistically, we further find that ATG9B promoted CRC invasion mainly through autophagy-independent manner. MYH9 is the pivotal interacting protein for ATG9B functioning, which directly binds to cytoplasmic peptide segments aa368-411 of ATG9B by its head domain. Furthermore, the combination of ATG9B and MYH9 enhance the stability of each other by decreasing their binding to E3 ubiquitin ligase STUB1, therefore preventing them from ubiquitin-mediated degradation, which further amplified the effect of ATG9B and MYH9 in CRC cells. During CRC cell invasion, ATG9B is transported to the cell edge with the assistance of MYH9 and accelerates focal adhesion (FA) assembly through mediating the interaction of endocytosed integrin ß1 and Talin-1, which facilitated to integrin ß1 activation. Clinically, upregulated expression of ATG9B in human CRC tissue is always accompanied with highly elevated expression of MYH9 and associated with advanced CRC stage and poor prognosis. Taken together, this study highlighted the important role of ATG9B in CRC metastasis by promoting focal adhesion assembly, and ATG9B together with MYH9 can provide a pair of potential therapeutic targets for preventing CRC progression.

Correction to: Downregulation of GLYR1 contributes to microsatellite instability colorectal cancer by targeting p21 via the p38MAPK and PI3K/AKT pathways.

An amendment to this paper has been published and can be accessed via the original article.

Downregulation of GLYR1 contributes to microsatellite instability colorectal cancer by targeting p21 via the p38MAPK and PI3K/AKT pathways.

BACKGROUND: GLYR1 has a high mutation frequency in microsatellite instability colorectal cancer (MSI CRC) and is presumed to be a novel tumor suppressor. However, the role of GLYR1 in tumors has never been studied. In particular, the downregulation of GLYR1 in MSI CRC is worthy of further investigation. METHODS: Western blot and immunohistochemistry analyses were used to detect GLYR1 protein expression in CRC tissues and cell lines, and the clinical significance of GLYR1 was also analyzed. The relationship between GLYR1 and MLH1 was validated by immunofluorescence, immunoprecipitation and bioinformatics analyses. Western blotting, qRT-PCR, CCK-8 assays, colony formation assays, flow cytometry and Hoechst 33258 staining assays were used to assess the effect of GLYR1 on the cell cycle progression, proliferation, differentiation and apoptosis of CRC cells in vitro. The related mechanisms were initially investigated by Western blotting. RESULTS: GLYR1 was significantly downregulated in MSI CRC and its expression was negatively correlated with tumor size and positively correlated with tumor differentiation in CRC patients. In addition, GLYR1 interacted with MLH1 to regulate its nuclear import and expression. Moreover, downregulation of GLYR1 accelerated G1/S phase transition, promoted proliferation and inhibited differentiation of SW480 and SW620 cells in vitro. Furthermore, downregulation of GLYR1 decreased the sensitivity to 5-fluorouracil (5-FU) by inhibiting the mitochondrial apoptosis pathway in CRC cells. Inhibition of the p38 mitogen-activated protein kinase (p38MAPK) and activation of the phosphatidyl 3-kinase/protein kinase B (PI3K/Akt) signaling pathways were involved in the mechanism by which GLYR1 downregulated p21. CONCLUSIONS: Ours is the first study to elucidate the role of GLYR1 in tumors and provide evidence for GLYR1 as a biological marker that reflects the degree of malignancy and sensitivity to 5-FU in MSI CRC.

Primary epithelioid rhabdomyosarcoma of the stomach: a case report and review of literature.

BACKGROUND: Epithelioid rhabdomyosarcoma is a rare tumor that generally occurs in the bladder, the parotid gland, or the skin of the neck. We describe an unusual case of primary epithelioid rhabdomyosarcoma of the stomach and review the literature. CASE PRESENTATION: A 64-year-old woman presented with a lesion at the gastroesophageal junction. Histopathological examination showed irregularly sized round cells with low cytoplasmic content and eccentric nuclei. Mitotic figures were present. Fibrovascular septa and areas of necrosis were observed between tumor cells. Tumor cells were strongly positive for MyoD1, desmin, and myogenin, and weakly positive for actin, CD56, and PGP9.5. The ki-67 index was ≥90%. CONCLUSIONS: Primary epithelioid rhabdomyosarcoma of the stomach is extremely rare. Better awareness of this entity is necessary for early diagnosis and treatment.

Role of TGFß3-Smads-Sp1 axis in DcR3-mediated immune escape of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a leading cause of tumour-associated mortality worldwide, but no significant improvement in treating HCC has been reported with currently available systemic therapies. Immunotherapy represents a new frontier in tumour therapy. Therefore, the immunobiology of hepatocarcinoma has been under intensive investigation. Decoy receptor 3 (DcR3), a member of the tumour necrosis factor receptor (TNFR) superfamily, is an immune suppressor associated with tumourigenesis and cancer metastasis. However, little is known about the role of DcR3 in the immunobiology of hepatocarcinoma. In this study, we found that overexpression of DcR3 in HCC is mediated by the TGFß3-Smad-Sp1 signalling pathway, which directly targets DcR3 promoter regions. Moreover, overexpression of DcR3 in HCC tissues is associated with tumour invasion and metastasis and significantly promotes the differentiation and secretion of Th2 and Treg cells while inhibiting the differentiation and secretion of Th1 cells. Conversely, knockdown of DcR3 expression in HCC significantly restored the immunity of CD4+ T cells. Inhibition of DcR3 expression may provide a novel immunotherapeutic approach to restoring immunity in HCC patients.

Cancer-associated fibroblasts promote colorectal cancer progression by secreting CLEC3B.

Nontumour cells in the tumour microenvironment, especially fibroblasts, contribute to tumour progression and metastasis. The occurrence and evolution of colorectal cancer (CRC) is closely related to cancer-associated fibroblasts (CAFs). The aim of this work was to evaluate the effects of the growth factors and cytokines secreted by CAFs on CRC progression. The secreted cytokines were examined in CAFs by Human Cytokine Antibody array. We screened 37 differentially secreted cytokines in the culture supernatants of CAFs and NFs. CLEC3B, attractin, kallikrein 5 and legumain were selected for further verification. CLEC3B was more highly expressed in the stroma of CRC tissues than the other 3 cytokines. Immunohistochemistry revealed that CLEC3B expression was associated with serosal invasion by CRC. Patients with co-expression of CLEC3B and α-SMA had worse survival outcomes than those with only CLEC3B or α-SMA expression. CLEC3B secreted from CAFs may promote tumour migration. Knockdown of endogenous CLEC3B in CAFs markedly decreased CRC cell migration, while recombinant human CLEC3B clearly promoted CRC cell migration and actin remodelling. In conclusion, our findings suggest that CAFs promote the CRC cell migration and skeletal reorganization by secreting CLEC3B. CLEC3B might be a potential therapeutic molecule for CRC treatment.

Gastric aggressive fibromatosis: report of a case and review of the literature.

OBJECTIVES: To describe a rare case of aggressive fibromatosis of the stomach and discuss the differential diagnoses. METHODS: A 47-year-old man presented with nonspecific abdominal pain. Gastroscopy revealed stomach wall swelling. An antral gastrectomy was performed. Histological examination revealed spindle-shaped cells and morphology typical of aggressive fibromatosis. We performed a literature search to identify conditions with features similar to those of aggressive fibromatosis. RESULTS: Aggressive fibromatosis does not metastasize, but it is locally invasive and has a tendency to relapse; however, our patient has not had recurrence > 1 year after surgery. Aggressive fibromatosis of the stomach may be confused with an inflammatory fibroid polyp, a gastrointestinal stromal tumor, schwannoma, leiomyoma, inflammatory myofibroblastic tumor, scirrhous carcinoma of the stomach, follicular dendritic cell sarcoma, inflammatory malignant fibrous histiocytoma, myofibroma/myofibromatosis, and solitary fibrous tumor of the stomach. CONCLUSIONS: Aggressive fibromatosis of the stomach is a rare spindle cell tumor that must be differentiated from a variety of conditions.

FSTL1 interacts with VIM and promotes colorectal cancer metastasis via activating the focal adhesion signalling pathway.

Follistatin-like protein 1 (FSTL1) has been reported to have both tumour-promoting and tumour-suppressive characters. However, the role of FSTL1 in colorectal cancer (CRC) remains unclear. Here we showed that FSTL1 expression was significantly up-regulated in CRC tissues compared with the paired normal tissues. In addition, the higher FSTL1 expression was associated with the infiltrating depth, lymph node metastasis and poor prognosis of CRC. Enhanced expression of FSTL1 distinctly increased cell migration and invasion in vitro, as well as promoting liver metastasis of CRC in vivo. Conversely, knockdown of FSTL1 expression significantly repressed invasion and metastasis of CRC. Mechanically, transcription factor Smad3 was involved in FSTL1 protein expression inducing by TGFß1-Smad2/3 signalling. Furthermore, this effect of FSTL1 in promoting CRC progression was actualised via activating focal adhesions signalling pathway and regulating cytoskeleton rearrangement. We identified VIM, as an interactive protein of FSTL1, participated in FSTL1-mediated aggressive phenotype. We showed the role of FSTL1 in CRC and explored its transcription regulation and downstream signalling molecular mechanisms. In conclusion, our findings suggested that FSTL1 promoted CRC progression and metastasis, making it a novel target for diagnosis and prognostic evaluation of CRC.

RGC32 induces epithelial-mesenchymal transition by activating the Smad/Sip1 signaling pathway in CRC.

Response gene to complement 32 (RGC32) is a transcription factor that regulates the expression of multiple genes involved in cell growth, viability and tissue-specific differentiation. However, the role of RGC32 in tumorigenesis and tumor progression in colorectal cancer (CRC) has not been fully elucidated. Here, we showed that the expression of RGC32 was significantly up-regulated in human CRC tissues versus adjacent normal tissues. RGC32 expression was significantly correlated with invasive and aggressive characteristics of tumor cells, as well as poor survival of CRC patients. We also demonstrated that RGC32 overexpression promoted proliferation, migration and tumorigenic growth of human CRC cells in vitro and in vivo. Functionally, RGC32 facilitated epithelial-mesenchymal transition (EMT) in CRC via the Smad/Sip1 signaling pathway, as shown by decreasing E-cadherin expression and increasing vimentin expression. In conclusion, our findings suggested that overexpression of RGC32 facilitates EMT of CRC cells by activating Smad/Sip1 signaling.

DcR3 induces epithelial-mesenchymal transition through activation of the TGF-ß3/SMAD signaling pathway in CRC.

Decoy receptor 3 (DcR3), a novel member of the tumor necrosis factor receptor (TNFR) family, was recently reported to be associated with tumorigenesis and metastasis. However, the role of DcR3 in human colorectal cancer (CRC) has not been fully elucidated. In this study, we found that DcR3 expression was significantly higher in human colorectal cancer tissues than in paired normal tissues, and that DcR3 expression was strongly correlated with tumor invasion, lymph node metastases and poor prognoses. Moreover, DcR3 overexpression significantly enhanced CRC cell proliferation and migration in vitro and tumorigenesis in vivo. Conversely, DcR3 knockdown significantly repressed CRC cell proliferation and migration in vitro, and DcR3 deficiency also attenuated CRC tumorigenesis and metastasis in vivo. Functionally, DcR3 was essential for TGF-ß3/SMAD-mediated epithelial-mesenchymal transition (EMT) of CRC cells. Importantly, cooperation between DcR3 and TGF-ß3/SMAD-EMT signaling-related protein expression was correlated with survival and survival time in CRC patients. In conclusion, our results demonstrate that DcR3 may be a prognostic biomarker for CRC and that this receptor facilitates CRC development and metastasis by participating in TGF-ß3/SMAD-mediated EMT of CRC cells.

AKAP-9 promotes colorectal cancer development by regulating Cdc42 interacting protein 4.

Our previous studies have shown that PRKA kinase anchor protein 9 (AKAP-9) is involved in colorectal cancer (CRC) cell proliferation and migration in vitro. However, whether or not AKAP-9 is important for CRC development or metastasis in vivo remains unknown. In the present study, we found that AKAP-9 expression was significantly higher in human colorectal cancer tissues than the paired normal tissues. In fact, AKAP-9 level correlated with the CRC infiltrating depth and metastasis. Moreover, the higher AKAP-9 expression was associated with the lower survival rate in patients. In cultured CRC cells, knockdown of AKAP-9 inhibited cell proliferation, invasion, and migration. AKAP-9 deficiency also attenuated CRC tumor growth and metastasis in vivo. Mechanistically, AKAP-9 interacted with cdc42 interacting protein 4 (CIP4) and regulated its expression. CIP4 levels were interrelated to the AKAP-9 level in CRC cells. Functionally, AKAP-9 was essential for TGF-ß1-induced epithelial-mesenchymal transition of CRC cells, and CIP4 played a critical role in mediating the function of AKAP-9. Importantly, CIP4 expression was significantly up-regulated in human CRC tissues. Taken together, our results demonstrated that AKAP-9 facilitates CRC development and metastasis via regulating CIP4-mediated epithelial-mesenchymal transition of CRC cells.

Long non-coding RNA MALAT1 increases AKAP-9 expression by promoting SRPK1-catalyzed SRSF1 phosphorylation in colorectal cancer cells.

Our earlier findings indicate that the long non-coding RNA MALAT1 promotes colorectal cancer (CRC) cell proliferation, invasion and metastasis in vitro and in vivo by increasing expression of AKAP-9. In the present study, we investigated the molecular mechanism by which MALAT1 enhances AKAP9 expression in CRC SW480 cells. We found that MALAT1 interacts with both SRPK1 and SRSF1. MALAT1 increases AKAP-9 expression by promoting SRPK1-catalyzed SRSF1 phosphorylation. Following MALAT1 knockdown, overexpression of SRPK1 was sufficient to restore SRSF1 phosphorylation and AKAP-9 expression to a level that promoted cell proliferation, invasion and migration in vitro. Conversely, SRPK1 knockdown after overexpression of MALAT1 in SW480 cells diminished SRSF1 phosphorylation and AKAP-9 expression and suppressed cell proliferation, invasion and migration in vitro. These findings suggest MALAT1 increases AKAP-9 expression by promoting SRPK1-catalyzed SRSF1 phosphorylation in CRC cells. These results reveal a novel molecular mechanism by which MALAT1 regulates AKAP-9 expression in CRC cells.

NDRG1 attenuates epithelial-mesenchymal transition of nasopharyngeal cancer cells via blocking Smad2 signaling.

N-myc downstream-regulated gene 1 (NDRG1) has been implicated in tumorigenesis and metastasis in different cancers. However, its role in nasopharyngeal carcinoma remains unknown. We found that NDRG1 expression level was high in nasopharyngeal cancer 5-8F cells but low in 5-8F-LN cells with lymphatic metastasis potential. Knockdown of NDRG1 by shRNA promoted 5-8F cell proliferation, migration, and invasion in vitro and its tumorigenesis in vivo. Moreover, NDRG1 deficiency induced an epithelial-mesenchymal transition (EMT) of 5-8F cells as shown by an attenuation of E-cadherin and an induction of N-cadherin and vimentin expression. NDRG1 knockdown also enhanced Smad2 expression and phosphorylation. Smad2 signaling was attenuated in 5-8F cells but was significantly activated in 5-8F-LN cells. Knockdown of Smad2 restored E-cadherin but attenuated N-cadherin expression in NDRG1-deficient 5-8F cells, suggesting a reduction of EMT. Consistently, blockade of Smad2 in 5-8F-LN cells increased E-cadherin while diminishing N-cadherin and vimentin expression. These data indicate that Smad2 mediates the NDRG1 deficiency-induced EMT of 5-8F cells. In tumors derived from NDRG1-deficient 5-8F cells, E-cadherin expression was inhibited while vimentin and Smad2 were increased in a large number of cancer cells. Most importantly, NDRG1 expression was attenuated in human nasopharyngeal carcinoma tissues, resulted in a lower survival rate in patients. The NDRG1 was further decreased in the detached nasopharyngeal cancer cells, which was associated with a further reduced survival rate in patients with lymphatic metastasis. Taken together, these results demonstrated that NDRG1 prevents nasopharyngeal tumorigenesis and metastasis via inhibiting Smad2-mediated EMT of nasopharyngeal cells.