[Translational research and diagnosis in GIST]

Methyltransferase-like 3 (METTL3) mediated N6-methyladenosine (m6A) modifications facilitate mir-25-3p maturation to promote gastrointestinal stromal tumors (GISTs) progression

BACKGROUND

Methyltransferase-like 3 (METTL3) is an RNA N6-methyladenosine (m6A) methyltransferase, which plays a critical role in micorRNA (miRNAs) processing and maturation, but it is still unclear whether METTL3 regulated miRNAs participates in the regulation of cancer aggressiveness in gastrointestinal stromal tumors (GISTs).

OBJECTIVES

This study was designed to investigate this issue, and uncover the potential underlying mechanisms.

METHODS

the expression of METTL3 in GISTs tissues and cell lines were determined by RT-qPCR and Western blot. Cell proliferation and migration were assessed by colony formation, CCK-8 and Transwell. The mRNA expression of all proteins was detected by RT-qPCR, and tumor xenograft study was applied to confirm the effect of METTL3 on GISTs development in vivo.

RESULTS

In our study, we showed that METTL3 was significantly upregulated in GISTs tissues and cell lines. Functional experiments demonstrated that overexpression of METTL3 promoted GISTs cell malignant biological behavior and tumor growth in vitro and in vivo, and conversely, silencing of METTL3 had opposite effects and suppressed GISTs progression. Further mechanistical experiments verified that METTL3 promoted the maturation of miR-25-3p in an m6A-dependent manner. Similar to METTL3, miR-25-3p was also validated as an oncogene to promote cancer development in GISTs. Finally, our rescuing experiments hinted that silencing of miR-25-3p abrogated the tumor-initiating effects of METTL3 overexpression on GISTs.

CONCLUSION

Collectively, those results indicated that METTL3 played an oncogenic role in GISTs through positively modulating the miR-25-3p in an m6A-dependent manner, and we firstly discussed how the METTL3/m6A/miR-25-3p axis affected GISTs development.

Impact of age and gender on tumor related prognosis in gastrointestinal stromal tumors (GIST)

Background

Risk classification and prediction of prognosis in GIST is still a matter of debate. Data on the impact of age and gender as potential confounding factors are limited. Therefore we comprehensively investigated age and gender as independent risk factors for GIST.

Methods

Two independent patient cohorts (cohort I, n = 87 [<50 years]; cohort II, n = 125 [≥50 years]) were extracted from the multicentre Ulmer GIST registry including a total of 659 GIST patients retrospectively collected in 18 collaborative German oncological centers. Based on demographic and clinicopathological parameters and a median follow-up time of 4.3 years (range 0.56; 21.33) disease-specific-survival (DSS), disease-free-survival (DFS) and overall survival (OS) were calculated.

Results

GIST patients older than fifty years showed significantly worse DSS compared to younger patients (p = 0.021; HR = 0.307, 95% CI [0.113; 0.834]). DSS was significantly more favorable in younger female GIST patients compared with elderly females (p = 0.008). Female gender resulted again in better prognosis in younger patients (p = 0.033).

Conclusions

Patient age (<50 years) and female gender were significantly associated with a more favourable prognosis in GIST. Extended studies are warranted to confirm our clinical results and to elucidate underlying pathophysiological mechanisms.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1054-y) contains supplementary material, which is available to authorized users.

Unique case of sporadic multiple gastro intestinal stromal tumour

INTRODUCTION

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract and they derived from transformed neoplastic precursors of Cajal's interstitial cell (ICC).

PRESENTATION OF THE CASE

We are presenting a sporadic and exemplary case of 42 multiple GISTs in a young female patient. Our patient showed anemia for the gastric GIST bleeding and only after other tumors were instrumentally and intra-surgery discovered. The patient showed genetic mutation V559A/1676 T>C of the juxtamembrane domain of the exon 11 causing the replacement of Valine with Alanine in the 559 codon.

DISCUSSION

GISTS estimated annual incidence is 12-14 per million. Multiple GISTs associated with familiarity or hereditary syndromes are described only in few case reports and sporadic mGISTs have not been studied yet. Literature review has been done.

CONCLUSION

We are presenting a sporadic and exemplary case of 42 multiple GISTs in a young female patient localized trough out all the gastrointestinal tract. This is the only case of sporadic multiple GISTs reported in literature.

Gastrointestinal stromal tumor - an evolving concept

Gastrointestinal stromal tumors (GISTs) are the most frequent mesenchymal tumors of the gastrointestinal tract. The discovery that these tumors, formerly thought of smooth muscle origin, are indeed better characterized by specific activating mutation in genes coding for the receptor tyrosine kinases (RTKs) CKIT and PDGFRA and that these mutations are strongly predictive for the response to targeted therapy with RTK inhibitors has made GISTs the typical example of the integration of basic molecular knowledge in the daily clinical activity. The information on the mutational status of these tumors is essential to predict (and subsequently to plan) the therapy. As resistant cases are frequently wild type, other possible oncogenic events, defining other "entities," have been discovered (e.g., succinil dehydrogenase mutation/dysregulation, insuline growth factor expression, and mutations in the RAS-RAF-MAPK pathway). The classification of disease must nowadays rely on the integration of the clinico-morphological characteristics with the molecular data.