Absence of RKIP expression is an independent prognostic biomarker for gastric cancer patients

Bmi-1 promotes the proliferation, migration and invasion, and inhibits cell apoptosis of human retinoblastoma cells via RKIP

Retinoblastoma is one of the most common ocular malignancies in children. Bmi-1, a member of the Polycomb group family of transcriptional repressors, is expressed in a variety of tumors. The purpose of our study was to explore the role of Bmi-1 in retinoblastoma. RT-qPCR and western blot were used for calculating the mRNA and protein levels of Bmi-1 and RKIP. MTT, Wound healing and Transwell assays were performed to measure the proliferation, migration and invasion in retinoblastoma cells. Cell apoptosis was detected by flow cytometry. The volume and mass of transplanted tumors were detected in nude mice. Bmi-1 was over expressed, and RKIP was low expressed in retinoblastoma cells. Bmi-1 promoted cell proliferation, migration and invasion and suppressed cell apoptosis of Y79 and SO-RB50 cells. Downregulation of Bmi-1 and overexpression of RKIP inhibited cell proliferation, migration and invasion, and increased cell apoptosis. The functions of Bmi-1 knockdown on retinoblastoma cells were blocked by RKIP knockdown, but promoted by RKIP. Down-regulated Bmi-1 inhibited xenograft tumor growth, and RKIP exacerbated this inhibitory effect. Bmi-1 served as a potential therapeutic target for improving the efficacy of clinical treatment in retinoblastoma. All the findings revealed the functions of Bmi-1/RKIP axis in retinoblastoma tumorigenesis.

[MiR-4443 promotes migration and invasion of breast cancer cells by inhibiting PEBP1 expression]

OBJECTIVE

To investigate the effect of miR-4443 expression on migration and invasion of breast cancer.

METHODS

We examined the expression of miR-4443 in breast carcinoma in situ and paired adjacent tissues from 3 breast cancer patients with high-throughput sequencing and verified the results using TCGA database. We also detected miR-4443 expressions using real-time quantitative PCR (RT-qPCR) in low invasive and highly invasive breast cancer cells (MCF-7 and MDA-MB-231 cells, respectively). The changes in apoptosis, migration and invasion of MCF-7 and MDA-MB-231 cells after transfection with miR-4443 mimics, mimics-NC, miR-4443 inhibitor or inhibitor-NC were analyzed using flow cytometry, wound healing assay and Transwell invasion assay. The target gene of miR-4443 was predicted by bioinformatics software and validated by a dual luciferase reporter gene system. RT-qPCR and Western blotting were performed to detect the expression of recombinant human phosphatidyl ethanolamine binding protein 1 (PEBP1) in the transfected cells.

RESULTS

The expression of miR-4443 was significantly higher in the breast cancer tissues than in the adjacent tissues (P < 0.01), and was significantly up-regulated in MDA-MB-231 cells as compared with MCF-7 cells (P < 0.01). Transfection with miR-4443 mimics or inhibitors did not obviously affect apoptosis rate of the breast cancer cells (P>0.05), but significantly enhanced or weakened the migration and invasion abilities of the cells, respectively (P < 0.01). Bioinformatic analysis identified PEBP1 as the target gene of miR-4443 with a close correlation with metastasis of breast cancer (P < 0.01), and the result was confirmed by double luciferase reporter gene assay. The mRNA and protein expression of PEBP1 were significantly lower in MDA-MB-231 cells than in MCF-7 cells (P < 0.01), and miR-4443 over-expression or knockdown significantly down-regulated or up-regulated PEBP1 expressions in the cells, respectively (P < 0.01).

CONCLUSIONS

MiR-4443 promotes the migration and invasion of breast cancer cells by inhibiting the expression of PEBP1, suggesting the possibility of suppressing miR-4443 expression as a potential therapeutic strategy for breast cancer.

Downregulation of RKIP promotes radioresistance of nasopharyngeal carcinoma by activating NRF2/NQO1 axis via downregulating miR-450b-5p

Dysregulation of RKIP and NRF2 has been widely involved in the therapy resistance of multiple malignances, however, their relation and the corresponding mechanisms, especially in radiation response, have not been elucidated. In this study, we revealed that RKIP could negatively regulate the expression of NRF2 in nasopharyngeal carcinoma (NPC) cells. Depletion or ectopic expression of NRF2 countered the pro- or anti- radioresistant effects of RKIP knockdown or overexpression on NPC cells, respectively, both in vitro and in vivo. Furthermore, our results indicated that NQO1 was positively regulated by NRF2 and served as the downstream effector of RKIP/NRF2 axis in regulation of NPC radioresistance. Mechanistically, miR-450b-5p, being positively regulated by RKIP in NPC cells, could sensitize NPC cells to irradiation by directly targeting and suppressing the level of NRF2. Besides, we analyzed the level of aforementioned molecules in NPC tissues. The results indicated that RKIP was significantly downregulated, NRF2 and NQO1 were notably upregulated in NPC tissues compared with in normal nasopharyngeal mucosa (NNM) tissues. Furthermore, RKIP and miR-450b-5p were remarkably lower, yet NRF2 and NQO1 were notably higher, in radioresistant NPC tissues relative to in radiosensitive NPC tissues. Consistent with the pattern in NPC cells, the RKIP/miR-450b-5p/NRF2/NQO1 axis was significantly correlated in NPC tissues. Downregulation of RKIP and miR-450b-5p, and upregulation of NRF2 and NQO1, positively correlated to malignant pathological parameters such as primary T stage, Lymph node (N) metastasis, and TNM stage. Finally, RKIP and miR-450b-5p served as favorable prognostic indicators, and NRF2 and NQO1 acted as unfavorable prognostic biomarkers in patients with NPC. Collectively, our outcomes reveal that RKIP downregulation promotes radioresistance of NPC by downregulating miR-450b-5p and subsequently upregulating and activating NRF2 and NQO1, highlighting RKIP/miR-450b-5p/NRF2/NQO1 axis as a potential therapeutic target for improving the radiosensitivity of NPC.

A 30-Year Long-Term Experience in Appendix Neuroendocrine Neoplasms-Granting a Positive Outcome

Neuroendocrine neoplasms (NENs) are the most common tumor of the appendix and have an excellent prognosis. Appendiceal tumors diagnosed between 1989 and 2019 were reviewed, and clinical data were collected from patient files. Part of the series was immuno-profiled for markers related to cell cycle proliferation and/or senescence-type, apoptotic, and metastatic potential. Appendix NENs were detected in 74 patients, with 0.47% of incidence per appendectomy. The median age of the patients was 21.5 years, with two age peaks of incidence at 17.0 and 55.2 years. The median tumors size was 5.8 mm, and most were smaller than 10 mm. Lymphovascular and perineural invasion, as well as necrosis, was associated with larger tumor size. G1 tumors composed 96.0% of the cohort. The presence of moderate/strong p16 and the absent/low Bcl-2 expression was frequently observed and associated with a smaller size. This study represents one of the largest cohorts and with a long follow-up. For tumors smaller than 10 mm appendicectomy was sufficient as a curative procedure, as revealed by the good outcome. This series presented a 100% disease-free survival. The indolent phenotype of appendix NENs is supported by the expression of markers that point towards a strong inhibition of cell replication and growth inhibition.

RKIP as an Inflammatory and Immune System Modulator: Implications in Cancer

Raf kinase inhibitor protein (RKIP), an important modulator of intracellular signalling pathways, is commonly downregulated in multiple cancers. This reduction, or loss of expression, is correlated not only with the presence of metastasis, contributing to RKIP’s classification as a metastasis suppressor, but also with tumour aggressiveness and poor prognosis. Recent findings suggest a strong involvement of RKIP in the modulation of tumour microenvironment components, particularly by controlling the infiltration of specific immune cells and secretion of pro-metastatic factors. Additionally, RKIP interaction with multiple signalling molecules seems to potentiate its function as a regulator of inflammatory processes, mainly through stimulation of anti- or pro-inflammatory cytokines. Furthermore, RKIP is involved in the modulation of immunotherapeutic drugs response, through diverse mechanisms that sensitize cells to apoptosis. In the present review, we will provide updated information about the role of RKIP as an inflammatory and immune modulator and its potential implications in cancer will be addressed.

Loss of SPINT2 expression frequently occurs in glioma, leading to increased growth and invasion via MMP2

PURPOSE

High-grade gliomas (HGG) remain one of the most aggressive tumors, which is primarily due to its diffuse infiltrative nature. Serine proteases and metalloproteases are known to play key roles in cellular migration and invasion mechanisms. SPINT2, also known as HAI-2, is an important serine protease inhibitor that can affect MET signaling. SPINT2 has been found to be frequently downregulated in various tumors, whereby hypermethylation of its promoter appears to serve as a common mechanism. Here, we assessed the clinical relevance of SPINT2 expression and promoter hypermethylation in pediatric and adult HGG and explored its functional role.

METHODS

A series of 371 adult and 77 pediatric primary HGG samples was assessed for SPINT2 protein expression (immunohistochemistry) and promoter methylation (methylation-specific PCR) patterns. After SPINT2 knockdown and knock-in in adult and pediatric HGG cell lines, a variety of in vitro assays was carried out to determine the role of SPINT2 in glioma cell viability and invasion, as well as their mechanistic associations with metalloprotease activities.

RESULTS

We found that SPINT2 protein expression was frequently absent in adult (85.3%) and pediatric (100%) HGG samples. The SPINT2 gene promoter was found to be hypermethylated in approximately half of both adult and pediatric gliomas. Through functional assays we revealed a suppressor activity of SPINT2 in glioma cell proliferation and viability, as well as in their migration and invasion. These functions appear to be mediated in part by MMP2 expression and activity.

CONCLUSIONS

We conclude that dysregulation of SPINT2 is a common event in both pediatric and adult HGG, in which SPINT2 may act as a tumor suppressor.

Current Status of Raf Kinase Inhibitor Protein (RKIP) in Lung Cancer: Behind RTK Signaling

Lung cancer is the most deadly neoplasm with the highest incidence in both genders, with non-small cell lung cancer (NSCLC) being the most frequent subtype. Somatic mutations within the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) gene are key drivers of NSCLC progression, with EGFR inhibitors being particularly beneficial for patients carrying the so-called “EGFR-sensitizing mutations”. However, patients eventually acquire resistance to these EGFR inhibitors, and a better knowledge of other driven and targetable proteins will allow the design of increasingly accurate drugs against patients’ specific molecular aberrations. Raf kinase inhibitory protein (RKIP) is an important modulator of relevant intracellular signaling pathways, including those controlled by EGFR, such as MAPK. It has been reported that it has metastasis suppressor activity and a prognostic role in several solid tumors, including lung cancer. In the present review, the potential use of RKIP in the clinic as a prognostic biomarker and predictor of therapy response in lung cancer is addressed.

RKIP: A Key Regulator in Tumor Metastasis Initiation and Resistance to Apoptosis: Therapeutic Targeting and Impact

RAF-kinase inhibitor protein (RKIP) is a well-established tumor suppressor that is frequently downregulated in a plethora of solid and hematological malignancies. RKIP exerts antimetastatic and pro-apoptotic properties in cancer cells, via modulation of signaling pathways and gene products involved in tumor survival and spread. Here we review the contribution of RKIP in the regulation of early metastatic steps such as epithelial⁻mesenchymal transition (EMT), migration, and invasion, as well as in tumor sensitivity to conventional therapeutics and immuno-mediated cytotoxicity. We further provide updated justification for targeting RKIP as a strategy to overcome tumor chemo/immuno-resistance and suppress metastasis, through the use of agents able to modulate RKIP expression in cancer cells.

Loss of Raf kinase inhibitor protein expression is associated with human papillomavirus 16 infection in anal tumors

There has been an increase in the incidence of anal cancer in the past two decades, with squamous cell carcinoma (SCC) being the most frequent histological type identified. Among the risk factors, high-risk human papillomavirus (HPV) infection is the most pervasive. Raf kinase inhibitor protein (RKIP) is expressed in a number of normal human tissues and previous studies have demonstrated the prognostic value of the loss of RKIP expression in several gastrointestinal tumors. Therefore, the present study aimed to evaluate the clinical implications of RKIP expression in a series of neoplastic lesions of the anal canal. The resected tumors of 48 patients [8 high-grade intraepithelial lesions (HSILs), 14 adenocarcinomas and 26 squamous cell carcinomas (SCCs)] were immunohistochemically evaluated for RKIP expression, and the results were correlated with clinicopathological data. The results identified a decreased 5-year overall survival rate in patients with adenocarcinoma (40.8%) compared with patients with SCC (76.7%), and a decreased 5-year disease-free survival rate in patients at clinical stages III/IV (37.3 vs. 62.5 and 82.6% for clinical stages 0 and I/II, respectively). Low RKIP expression was revealed in 62.5% of HSILs, 88.5% of SCCs and 100.0% of the adenocarcinomas. High RKIP expression was associated with patient ethnicity (37.5% in non-Caucasians vs. 7.5% in Caucasians) and patient age (33.3% in younger patients vs. 0.0% in older patients). Finally, high RKIP expression was correlated with HPV16 infection status (40% in HPV^- vs. 5.3% in HPV⁺ patients). A correlation was identified between high RKIP expression and lesions with a generally improved prognosis, such as those diagnosed in younger patients, in situ lesions and lesions of lower clinical grades; there was also a negative correlation between high RKIP expression and HPV16 positivity in patients.

Molecular alterations of cancer cell and tumour microenvironment in metastatic gastric cancer

The term metastasis is widely used to describe the endpoint of the process by which tumour cells spread from the primary location to an anatomically distant site. Achieving successful dissemination is dependent not only on the molecular alterations of the cancer cells themselves, but also on the microenvironment through which they encounter. Here, we reviewed the molecular alterations of metastatic gastric cancer (GC) as it reflects a large proportion of GC patients currently seen in clinic. We hope that further exploration and understanding of the multistep metastatic cascade will yield novel therapeutic targets that will lead to better patient outcomes.

Prognostic value of diffuse versus intestinal histotype in patients with gastric cancer: a systematic review and meta-analysis

BACKGROUND

There are two distinct types of gastric carcinoma (GC), intestinal, more frequently sporadic and linked to environmental factors, and diffuse (undifferentiated) that is highly metastatic and characterized by rapid disease progression and a poor prognosis. However, there are many conflicting data in the literature concerning the association between histology and prognosis in GC. This meta-analysis was performed to provide demonstration if histology according to Lauren classification is associated with different prognosis in patients with GC.

METHODS

We searched PubMed, the Cochrane Library, SCOPUS, Web of Science, CINAHL, and EMBASE for all eligible studies. The combined hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) in terms of overall survival (OS) were evaluated.

RESULTS

A total of 73 published studies including 61,468 patients with GC were included in this meta-analysis. Our analysis indicates that GC patients with diffuse-type histology have a worst prognosis than those with intestinal subgroup in all studies (HR 1.23; 95% CI, 1.17-1.29; P<0.0001), in both loco-regional confined (HR 1.21; 95% CI, 1.12-1.30; P<0.0001) and advanced disease (HR 1.25; 95% CI, 1.046-1.50; P=0.014), in Asiatic (HR 1.2; 95% CI, 1.14-1.27; P<0.0001) and Western patients (HR 1.3; 95% CI, 1.19-1.41; P<0.0001), and in those not exposed (HR 1.15; 95% CI, 1.07-1.24; P<0.0001) or exposed (HR 1.27; 95% CI, 1.17-1.37; P<0.0001) to (neo)adjuvant therapy.

CONCLUSIONS

Our results indicated that histology might be a useful prognostic marker for both early and advanced GC patients, with intestinal-type associated with a better outcome. This information could be used for stratification purpose in future clinical trials.

Raf Kinase Inhibitor Protein Expression and Prognostic Value in Soft Tissue Sarcomas

OBJECTIVE

Soft tissue sarcomas (STSs) are heterogeneous tumors displaying multiple and complex molecular abnormalities with no specific pattern. Despite current therapeutic advances, the patients with STS still have a poor outcome, which makes it necessary to find out new prognostic markers. The Raf kinase inhibitory protein (RKIP) has been associated with prognosis in several human neoplasms; however, its role in STS is unknown.

METHODS

In the present study RKIP expression was assessed by immunohistochemistry in a series of 87 STSs, and its expression profile was associated with the patients' pathological parameters.

RESULTS

We found that RKIP is expressed in the cytoplasm of the great majority of cases, and absent in only approximately 18% of cases (16/87). Importantly, we observed that loss of RKIP expression was associated with poor outcome, constituting an independent prognostic marker.

CONCLUSION

This is the first study assessing RKIP expression levels in STS. We showed that loss of RKIP expression is present in a small subset of cases; however, its absence was associated with poor survival and may be a potential marker for STS prognosis.

SPINT2 Deregulation in Prostate Carcinoma

SPINT2 is a tumor suppressor gene that inhibits proteases implicated in cancer progression, like HGFA, hepsin and matriptase. Loss of SPINT2 expression in tumors has been associated with gene promoter hypermethylation; however, little is known about the mechanisms of SPINT2 deregulation in prostate cancer (PCa). We aimed to analyze SPINT2 expression levels and understand the possible regulation by SPINT2 promoter hypermethylation in PCa. In a cohort of 57 cases including non-neoplastic and PCa tissues, SPINT2 expression and promoter methylation was analyzed by immunohistochemistry and methylation-specific PCR, respectively. Methylation status of the SPINT2 promoter was also evaluated by bisulfite sequencing and 5-aza-2'-deoxycytidine treatment. Oncomine and TCGA databases were used to perform in silico PCa analysis of SPINT2 mRNA and methylation levels. A reduction in SPINT2 expression levels from non-neoplastic to PCa tissues was observed; however, none of the cases exhibited SPINT2 promoter methylation. Both bisulfite sequencing and 5-aza demonstrated that SPINT2 promoter is not methylated in PCa cells. Bioinformatics approaches did not show downregulation of SPINT2 at the mRNA level and, in corroboration with our results, SPINT2 promoter region is reported to be unmethylated. Our study suggests an involvement of SPINT2 in PCa tumorigenesis, probably in association with a post-translational regulation of SPINT2.

Clinicopathological features and prognostic implications of Raf kinase inhibitor protein downregulation in tongue squamous cell carcinoma

Raf kinase inhibitor protein (RKIP) is recognized as a suppressor of metastasis, and the downregulation of RKIP is associated with aggressive events and a poor outcome in a variety of solid tumors. However, the clinical relevance of RKIP expression in tongue squamous cell carcinoma (TSCC) remains unclear. In the present study, the expression of RKIP in 85 pairs of TSCC and corresponding adjacent non-cancerous tissues, 30 matched metastatic lesions from the cervical lymph nodes and 32 oral leukoplakia samples were assessed using immunohistochemical methods. The association between RKIP expression and clinicopathological features was then evaluated. Kaplan-Meier survival analysis and Cox proportional hazards model were used to estimate the effect of RKIP expression on the survival time of patients with TSCC. The results revealed that RKIP expression was dramatically downregulated in TSCC, and to an even greater extent in metastatic lesions. RKIP downregulation was significantly associated with the presence of lymphatic metastasis and the clinical stage of TSCC. Furthermore, patients with low RKIP expression demonstrated a significantly shorter overall survival time. Multivariate analysis indicated that RKIP expression may be an independent prognostic factor in TSCC. In conclusion, the present findings indicate that the lack of RKIP expression is of clinical significance and may serve as a prognostic biomarker in TSCC.

RKIP inhibition in cervical cancer is associated with higher tumor aggressive behavior and resistance to cisplatin therapy

Cervical cancer is one of the most common cancers in women worldwide, being high-risk group the HPV infected, the leading etiological factor. The raf kinase inhibitory protein (RKIP) has been associated with tumor progression and metastasis in several human neoplasms, however its role on cervical cancer is unclear. In the present study, 259 uterine cervix tissues, including cervicitis, cervical intraepithelial lesions and carcinomas, were analyzed for RKIP expression by immunohistochemistry. We found that RKIP expression was significantly decreased during malignant progression, being highly expressed in non-neoplastic tissues (54% of the samples; 73/135), and expressed at low levels in the cervix invasive carcinomas (∼15% (19/124). Following in vitro downregulation of RKIP, we observed a viability and proliferative advantage of RKIP-inhibited cells over time, which was associated with an altered cell cycle distribution and higher colony number in a colony formation assay. An in vitro wound healing assay showed that RKIP abrogation is associated with increased migratory capability. RKIP downregulation was also associated with an increased vascularization of the tumors in vivo using a CAM assay. Furthermore, RKIP inhibition induced cervical cancer cells apoptotic resistance to cisplatin treatment. In conclusion, we described that RKIP protein is significantly depleted during the malignant progression of cervical tumors. Despite the lack of association with patient clinical outcome, we demonstrate, in vitro and in vivo, that loss of RKIP expression can be one of the factors that are behind the aggressiveness, malignant progression and chemotherapy resistance of cervical cancer.