80MAP17 promotes the tumorigenesis of papillary thyroid carcinoma by reducing the stability of p53.

Background: Papillary thyroid cancer (PTC) is an endocrine malignancy whose incidence has increased rapidly worldwide. MAP17 (PDZKIP1) is a small protein related to tumor progression. The aim of this study was to investigate the role of MAP17 in PTC and the underlying molecular mechanism. Methods: Bioinformatics, Western blotting and immunohistochemistry were used to analyze the expression of MAP17 in PTC. The gene transcription was measured by qPCR. Cell viability was determined by CCK8 assay. Cell growth was measured by clonal formation assay. Cell apoptosis was measured by TUNEL. Wound healing assay and transwell assay were used to measure the mobility of cells. The expression of E-cadherin and N-cadherin was determined by immunofluorescence. The effect of MAP17 on tumor growth was determined in animal experiments. Results: The results showed that MAP17 was up-regulated in PTC, which significantly promoted the growth and motility of PTC cells, but inhibited cell apoptosis. Besides, overexpression of MAP17 accelerated cycloheximide (CHX, a protein synthesis inhibitor)-induced p53 degradation, while low expression of MAP17 slowed down CHX-induced p53 degradation, suggesting that MAP17 can regulate p53 stability. Notably, NUMB exhibited an opposite effect on P53 stability. Interestingly, p53 overexpression reversed the effects of MAP17 overexpression on cell viability, motility, and apoptosis, indicating that p53 was involved in the progression of PTC. In vivo studies have shown that tumor growth was positively correlated with MAP17 expression and negatively correlated with p53 expression. Conclusion: Our findings revealed that MAP17 exhibited carcinogenic effects through interacting with NUMB to reduce the stability of p53, demonstrating that MAP17 may serve as a potential prognostic biomarker for PTC treatment.

MAP17 Expression in Colorectal Cancer Is a Prognostic Factor for Disease Recurrence and Dismal Prognosis Already in Early Stage Disease.

BACKGROUND: Disease recurrence in colorectal cancer constitutes a major cause of significant cancer-associated morbidity and mortality. MAP17 is a small protein, and its overexpression in malignant tumors has been correlated with aggressive tumor phenotypes. The aim of the present study was to investigate the expression patterns of MAP17 in colorectal cancer specimens and to assess its clinical significance. PATIENTS AND METHODS: Surgical specimens of 111 patients with primary resectable colorectal cancer constituted the study population. Expression of MAP17 was assessed by immunohistochemistry, and the results were correlated with clinical and survival data. RESULTS: MAP17 was expressed in cancer cells and endothelial cells of tumor blood vessels. Expression of MAP17 more than 10% was correlated with advanced disease stage (p < 0.001), higher T classification (p = 0.007), the presence of lymph node metastasis (p < 0.001), vascular (p = 0.013) and perineural invasion (p = 0.012). Patients exhibiting MAP17 expression of more than 30% in cancer cells compared to those expressing MAP17 less than 10% demonstrated a significantly worse 3-year progression-free survival (35.2 vs. 91%, p < 0.001) and 5-year overall survival (40.8 vs. 91%, p < 0.001). Cox regression analysis confirmed MAP17 expression of more than 30% as a prognostic marker of progression free survival (HR 0.136, 95% CI = 0.056-0.329, p < 0.001) and overall survival (HR 0.144 [95% CI) = 0.049-0.419, p < 0.001) independent of other clinicopathological characteristics. Statistically significantly worse 3-year progression-free survival and 5-year overall survival was demonstrated in the subgroup analysis of patients with early stage cancer only and high expression of MAP17. CONCLUSIONS: High MAP17 expression in patients with colorectal cancer is a significant risk factor for cancer-associated morbidity and mortality already in early stage disease.

MAP17 contributes to non-small cell lung cancer progression via suppressing miR-27a-3p expression and p38 signaling pathway.

PROBLEM AND AIM: The overexpression of MAP17 has been reported in various human carcinomas. However, its molecular mechanism in non-small cell lung cancer (NSCLC) has not been fully understood. Our study aimed to reveal the molecular mechanism of NSCLC that involved MAP17 and identify its target miRNA. METHODS: RT-qPCR and immunoblot assays were conducted to measure the expression of mRNA and protein in NSCLC tissues and cell lines. Meanwhile, the A549 cells (an NSCLC cell line) were randomly assigned to the MAP17 overexpression group, the MAP17 knockdown group and negative control group to study the roles of MAP17 in cell viability, cell proliferation, migration, invasion, and apoptosis by performing Trypan blue exclusion, MTT, colony formation, transwell, wound healing and flow-cytometric apoptosis assays. The luciferase reporter assay was conducted to confirm the target relationship between MAP17 and miR-27a-3p. RESULTS: The upregulation of MAP17 mRNA and protein was observed in NSCLC tissues and cell lines. In vitro, the positive roles of MAP17 on cell viability, migration, and invasion were confirmed in A549 cells. It was also found that MAP17 could inhibit cell apoptosis by suppressing the activation of the p38 pathway. This research eventually proved the target relationship between MAP17 and miR-27a-3p, and that miR-27a-3p reversed the effects of MAP17 in A549 cells by directly targeting MAP17. CONCLUSIONS: MAP17 plays an oncogenic role in NSCLC by suppressing the activation of the p38 pathway. Apart from that, the miR-27a-3p can inhibit the expression of MAP17 to suppress the NSCLC progression.

MAP17 (PDZK1IP1) and pH2AX are potential predictive biomarkers for rectal cancer treatment efficacy.

Rectal cancer represents approximately 10% of cancers worldwide. Preoperative chemoradiotherapy increases complete pathologic response and local control, although it offers a poor advantage in survivorship and sphincter saving compared with that of radiotherapy alone. After preoperative chemoradiotherapy, approximately 20% of patients with rectal cancer achieve a pathologic complete response to the removed surgical specimen; this response may be related to a better prognosis and an improvement in disease-free survival. However, better biomarkers to predict response and new targets are needed to stratify patients and obtain better response rates. MAP17 (PDZK1IP1) is a small, 17 kDa non-glycosylated membrane protein located in the plasma membrane and Golgi apparatus and is overexpressed in a wide variety of human carcinomas. MAP17 has been proposed as a predictive biomarker for reactive oxygen species, ROS, inducing treatments in cervical tumors or laryngeal carcinoma. Due to the increase in ROS, MAP17 is also associated with the marker of DNA damage, phosphoH2AX (pH2AX). In the present manuscript, we examined the values of MAP17 and pH2AX as surrogate biomarkers of the response in rectal tumors. MAP17 expression after preoperative chemoradiotherapy is able to predict the response to chemoradiotherapy, similar to the increase in pH2AX. Furthermore, we explored whether we can identify molecular targeted therapies that could help improve the response of these tumors to radiotherapy. In this sense, we found that the inhibition of DNA damage with olaparib increased the response to radio- and chemotherapy, specifically in tumors with high levels of pH2AX and MAP17.

EGFR-TKI resistance and MAP17 are associated with cancer stem cell like properties.

Patients with non-small-cell lung cancer (NSCLC) with sensitive epidermal growth factor receptor (EGFR) mutations generally react well to tyrosine kinase inhibitors (TKIs). However acquired resistance eventually occurs. Several mechanisms contribute to the resistance including T790M mutation, c-Met amplification and PIK3CA mutation. In recent years, cancer stem cells (CSCs) have been suggested to be involved in TKI resistance. MAP17 is aberrantly overexpressed in a number of malignancies. However, the expression pattern and function of MAP17 in CSCs are still unclear. The aim the present study was to illustrate the effect of CSC-like cells on the resistance to TKIs in EGFR mutant NSCLC cells and explore the possible role of MAP17 in CSCs. The EGFR mutant cell line PC9 was cultured under serum-deprived undifferentiated conditions. The CSC properties including expression of stem cell markers CD133, CD44, Oct-4 and ABCG2, ability of self-renewal, invasion, proliferation and tumorigenesis were examined. The expression of MAP17 was compared in sphere and parent cells. Sphere cells displayed stem cells phenotypes and were resistant to erlotinib. Sphere cells expressed higher levels of MAP17, and MAP17 was associated with self-renewal and TKI resistance. The function of MAP17 demonstrated to be partially dependent on Na-dependent glucose transporter 1. Collectively these findings suggest that MAP17 serves a role in TKI resistance through regulation of CSCs in lung cancer.

Elevation of MAP17 enhances the malignant behavior of cells via the Akt/mTOR pathway in hepatocellular carcinoma.

MAP17, a small non-glycosylated membrane protein, was significantly up-regulated in hepatocellular carcinoma (HCC) tissues in our previous genome-wide microarray analysis. In this study, quantitative real-time RT-PCR and immunohistochemistry were applied to examine MAP17 mRNA and protein expression in primary HCC and matched peritumoral tissues. The disease-free survival (DFS) and overall survival (OS) was estimated using the Kaplan-Meier analysis. The expression of MAP17 was significantly higher in HCC tissues compared to the paired peritumoral tissues at both mRNA and protein levels. High MAP17 expression was positively correlated with gender, distant metastasis, early recurrence (≤ 2 year), and serum alpha-fetoprotein (all p < 0.05). Kaplan-Meier analysis showed that the DFS (p = 0.004) and OS (p = 0.013) in HCC patients with elevated expression of MAP17 were much worse than that in the low expression subgroup. High level of MAP17 was also significantly associated with a high probability of HCC early recurrence after surgical resection (p = 0.005). Cox regression analysis indicated MAP17 was an independent prognostic factor for DFS (HR, 1.710; 95% CI, 1.156-2.449, p = 0.012) and OS (HR, 1.743; 95% CI, 1.152-2.639, p = 0.009) in HCC. Silencing MAP17 significantly inhibited the proliferation, invasion and migration of HCC cells in vitro, and decreased the expression levels of Akt, p-Akt (Ser473), mTOR, p-mTOR (Ser2448) and MMP-9. Suggesting MAP17 was a novel diagnostic and prognostic biomarker for HCC patients and promoted HCC cell proliferation, invasion and migration via the Akt/mTOR pathway.

The cargo protein MAP17 (PDZK1IP1) regulates the immune microenvironment.

Inflammation is a complex defensive response activated after various harmful stimuli allowing the clearance of damaged cells and initiating healing and regenerative processes. Chronic, or pathological, inflammation is also one of the causes of neoplastic transformation and cancer development. MAP17 is a cargo protein that transports membrane proteins from the endoplasmic reticulum. Therefore, its overexpression may be linked to an excess of membrane proteins that may be recognized as an unwanted signal, triggering local inflammation. Therefore, we analyzed whether its overexpression is related to an inflammatory phenotype. In this work, we found a correlation between MAP17 expression and inflammatory phenotype in tumors and in other inflammatory diseases such as Crohn's disease, Barrett's esophagus, COPD or psoriasis. MAP17 expression correlated also with the markers of inflammation HLAs, BBS10, HERC2, ADNP and PYCARD. Furthermore, we found that MAP17 expression directly regulates NFAT2 and IL-6 activation, inducing the differentiation of monocytes to dendritic cells and suggesting a causal role of MAP17 in inflammation. Immunohistochemistry confirms local inflammation, mainly CD45+ cells, at the site of expression of MAP17, at least in tumors, Crohn's and psoriasis. Therefore, our data indicates that the overexpression of the protein MAP17 plays important role in diseases involving chronic inflammation.

Efficacy of bortezomib in sarcomas with high levels of MAP17 (PDZK1IP1).

Sarcomas are malignant tumors accounting for a high percentage of cancer morbidity and mortality in children and young adults. Surgery and radiation therapy are the accepted treatments for most sarcomas; however, patients with metastatic disease are treated with systemic chemotherapy. Many tumors display marginal levels of chemoresponsiveness, and new treatment approaches are needed. MAP17 is a small non-glycosylated membrane protein overexpressed in carcinomas. The levels of MAP17 could be used as a prognostic marker to predict the response to bortezomib in hematological malignancies and in breast tumors. Therefore, we analyzed the expression of this oncogene in sarcomas and its relationship with clinico-pathological features, as well as tested whether it can be used as a new biomarker to predict the therapeutic response to bortezomib and new therapies for sarcomas. We found that the levels of MAP17 were related to clinical features and poor survival in a cohort of 69 patients with different sarcoma types, not being restricted to any special subtype of tumor. MAP17 expression is associated with poor overall survival (p<0.001) and worse disease-free survival (p=0.002). Cell lines with high levels of MAP17 show a better response to bortezomib in vitro. Furthermore, patient-derived xenografts (PDX) with high levels of MAP17 respond to bortezomib in vivo. Our results showed that this response is due to the lower levels of NFκB and autophagy activation. Therefore, we suggest that MAP17 is a new biomarker to predict the efficacy of bortezomib as a new therapy for sarcomas.

MAP17 (PDZKIP1) as a novel prognostic biomarker for laryngeal cancer.

Larynx cancer organ preservation treatments with chemo and radiotherapy have substantially improved laryngoesophageal dysfunction-free survival. However, both of them lead to a high incidence of acute and chronic toxicities and a significant number of patients relapse. To date, there is no evidence available to establish the group of patients that may benefit from preservation approaches and clinical criteria such as primary tumor extension or pretreatment tracheotomy are not validated. MAP17 is a small non-glycosylated membrane protein overexpressed in carcinomas. The tumoral behavior induced by MAP17 is associated with reactive oxygen species production in which SGLT1 seems involved. In this study we found that the levels of MAP17 were related to clinical findings and survival in a cohort of 58 patients with larynx cancer. MAP17 expression is associated with overall survival (p<0.001) and laryngoesophageal dysfunction-free survival (p=0.002). Locoregional control in patients with high MAP17 showed better outcomes than those with low MAP17 (p=0.016). Besides, a positive correlation was observed between MAP17 expression and SGLT (p=0.022) and the combination of high levels of MAP17/SGLT also led to an increased overall survival (p=0,028). These findings suggest that MAP17, alone or in combination with SGLT1, may become a novel predictive biomarker for laryngeal carcinoma.

MAP17, a ROS-dependent oncogene.

MAP17 is a small 17 kDa non-glycosylated membrane protein previously identified as being overexpressed in carcinomas. Breast tumor cells that overexpress MAP17 show an increased tumoral phenotype with enhanced proliferative capabilities both in the presence or the absence of contact inhibition, decreased apoptotic sensitivity, and increased migration. MAP17-expressing clones also grow better in nude mice. The increased malignant cell behavior induced by MAP17 is associated with an increase in reactive oxygen species (ROS) production, and the treatment of MAP17-expressing cells with antioxidants results in a reduction in the tumorigenic properties of these cells. The MAP17-dependent increase in ROS and tumorigenesis relies on its PDZ-binding domain because disruption of this sequence by point mutations abolishes the ability of MAP17 to enhance ROS production and tumorigenesis. MAP17 is overexpressed in a great variety of human carcinomas, including breast tumors. Immunohistochemical analysis of MAP17 during cancer progression demonstrates that overexpression of the protein strongly correlates with tumoral progression. Generalized MAP17 overexpression in human carcinomas indicates that MAP17 can be a good marker for tumorigenesis and, especially, for malignant progression.