Targeted therapy of gastrointestinal stromal tumours

Gastrointestinal Stromal Tumors of the Stomach: Is There Any Advantage of Robotic Resections? A Systematic Review and Meta-Analysis

Background: The role of robotic surgery for gastrointestinal stromal tumor (GIST) resection remains unclear. This systematic review and meta-analysis aimed to investigate the outcomes of robotic versus laparoscopic surgery in patients requiring surgery for gastric GISTs. Methods: MEDLINE, EMBASE, and the Cochrane databases were searched from inception to September 4, 2023. Two independent reviewers conducted a systematic review of the literature to select all types of analytic studies comparing robotic versus laparoscopic surgery for GISTs and reporting intraoperative, postoperative, and/or pathological outcomes. Results: Overall, 4 retrospective studies were selected, including a total of 264 patients, specifically 111 (42%) in the robotic and 153 (58%) in the laparoscopic group. Robotic surgery was associated with longer operating time (+42.46 min; 95% confidence interval [CI]: 9.34, 75.58; P=0.01; I2: 85%) and reduced use of mechanical staplers (odds ratio [OR]: 0.05; 95%CI: 0.02, 0.11; P<0.00001; I2: 92%;) compared with laparoscopy. Although nonsignificant, conversion to open surgery was less frequently reported for robotic surgery (2.7%) than laparoscopy (5.2%) (OR: 0.59; 95%CI: 0.17, 2.03; P=0.4; I2: 0%). No difference was found for postoperative and oncological outcomes. Conclusions: Robotic surgery for gastric GISTs provides similar intraoperative, postoperative, and pathological outcomes to laparoscopy, despite longer operative time.

MicroRNA-128 acts as a suppressor in the progression of gastrointestinal stromal tumor by targeting B-lymphoma Mo-MLV insertion region 1

INTRODUCTION

The critical role of microRNA-128 (miR-128) in gastrointestinal-related diseases has been documented. In the current study, we tried to clarify the specific role miR-128 in gastrointestinal stromal tumor (GIST) and the underlying mechanism.

METHODS

Differentially expressed genes in GIST were identified following bioinformatics analysis. Then, expression patterns of miR-128 and B-lymphoma Mo-MLV insertion region 1 (BMI-1) in clinical tissue samples and cell lines were characterized, followed by validation of their correlation. GIST-T1 cells were selected and transfected with different mimic, inhibitor, or siRNA plasmids, after which the biological functions were assayed.

RESULTS

We identified low miR-128 and high BMI-1 expression in GIST tissues of 78 patients and 4 GIST cell lines. Ectopic expression of miR-128 or silencing of BMI-1 suppressed the malignant potentials of GIST-T1 cells. As a target of miR-128, BMI-1 re-expression could partly counteract the suppressive effect of miR-128 on the malignancy of GIST-T1 cells.

CONCLUSION

Our study provided evidence that miR-128-mediated silencing of BMI-1 could prevent malignant progression of GIST, highlighting a promising anti-tumor target for combating GIST.

Challenges and Opportunities in Developing Targeted Therapies for Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is a heterogeneous group of breast cancers characterized by their lack of estrogen receptors, progesterone receptors, and the HER2 receptor. They are more aggressive than other breast cancer subtypes, with a higher mean tumor size, higher tumor grade, the worst five-year overall survival, and the highest rates of recurrence and metastasis. Developing targeted therapies for TNBC has been a major challenge due to its heterogeneity, and its treatment still largely relies on surgery, radiation therapy, and chemotherapy. In this review article, we review the efforts in developing targeted therapies for TNBC, discuss insights gained from these efforts, and highlight potential opportunities going forward. Accumulating evidence supports TNBCs as multi-driver cancers, in which multiple oncogenic drivers promote cell proliferation and survival. In such multi-driver cancers, targeted therapies would require drug combinations that simultaneously block multiple oncogenic drivers. A strategy designed to generate mechanism-based combination targeted therapies for TNBC is discussed.

Self-reported cognitive impairments and quality of life in patients with gastrointestinal stromal tumor: Results of a multinational survey

BACKGROUND

Cancer-related cognitive impairment (CRCI) has long-term effects on survivor quality of life, but CRCI research on patients with gastrointestinal stromal tumor (GIST) is lacking. The aims of this study were to investigate CRCI and concomitant quality of life among patients with GIST.

METHODS

An online survey was used to assess CRCI in adult patients with GIST using the validated Functional Assessment of Cancer Therapy-Cognitive-v.3. Age, education, demographically indexed IQ, general health, and quality of life factors (e.g., fatigue, emotional distress) were also assessed. The online survey was administered through five international GIST and sarcoma support organizations.

RESULTS

Over the 3-month recruitment period, the survey was completed by 485 participants: mean age, 57.80 (SD, 11.51), median 5 years after diagnosis. A majority (63.91%) reported experiencing cognitive symptoms with a significant negative quality of life impact. Controlling for age, patients with GIST ≥5 years after diagnosis reported worse cognitive function than those <5 years after diagnosis (p < .05) but did not differ in educational level or IQ. Whereas longer term survivors were more likely to have been treated with tyrosine kinase inhibitor (TKI) therapies, there was no observed association of TKI therapy with self-reported cognitive impairments.

CONCLUSIONS

A majority of GIST patients report cognitive symptoms that have a negative impact on quality of life, with longer term survivors (≥5 years) tending to report more cognitive impairments. Given the success of TKI therapy to substantially increase overall survival of patients with GIST, addressing CRCI in clinical practice may improve long-term GIST survivor function and quality of life.

Identification of Lethal Inhibitors and Inhibitor Combinations for Mono-Driver versus Multi-Driver Triple-Negative Breast Cancer Cells

There are no signaling-based targeted therapies for triple-negative breast cancer. The development of targeted cancer therapy relies on identifying oncogenic signaling drivers, understanding their contributions to oncogenesis and developing inhibitors to block such drivers. In this study, we determine that DU-4475 is a mono-driver cancer cell line relying on BRAF and the mitogen-activated protein kinase pathway for viability and proliferation. It is fully and lethally inhibited by BRAF or Mek inhibitors at low nM concentrations, but it is resistant to inhibitors targeting other signaling pathways. The inhibitory lethality caused by blocking Mek or BRAF is through apoptosis. In contrast, MDA-MB-231 is a multi-driver triple-negative breast cancer cell line dependent on both Src and the KRAS-activated mitogen-activated kinase pathway for proliferation and viability. Blocking each pathway alone only partially inhibits cell proliferation without killing them, but the combination of dasatinib, an Src inhibitor, and trametinib, a Mek inhibitor, achieves synthetic lethality. The combination is highly potent, with an IC50 of 8.2 nM each, and strikingly synergistic, with a combination index of less than 0.003 for 70% inhibition. The synthetic lethality of the drug combination is achieved by apoptosis. These results reveal a crucial difference between mono-driver and multi-driver cancer cells and suggest that pharmacological synthetic lethality may provide a basis for effectively inhibiting multi-driver cancers.

Evaluation of the therapeutic potential of masitinib and expression of its specific targets c-Kit, PDGFR-α, PDGFR-β, and Lyn in canine prostate cancer cell lines

Canine prostate cancer is classified into adenocarcinoma, transitional cell carcinoma with prostatic involvement, and mixed forms. Early metastatic spread leads to poor prognosis and limited treatment options. Masitinib is approved for the treatment of canine mast cell tumours and inhibits tyrosine kinase c-Kit, tyrosine-protein kinase Lyn (Lyn), and platelet-derived growth factor receptors alpha and beta (PDGFR-α, PDGFR-β), which are known to be expressed in canine prostate cancer. The aim of this study was to evaluate masitinib in an in vitro model consisting of cell lines from primary prostate adenocarcinoma, the associated lymph node metastasis of the same patient, and transitional cell carcinoma. To assess the suitability of the model system, the targets of masitinib were investigated by immunocytochemistry in the cell lines and by immunohistochemistry in the respective formalin-fixed, paraffin-embedded (FFPE) original neoplastic tissue. After exposure to masitinib, cell viability, cell count, apoptosis induction, and protein expression of c-Kit, Lyn, PDGFR-α, and PDGFR-β were assessed. To hedge the efficacy, two application protocols of masitinib (single application or 12-h double-dose regimen) were compared. Immunocytochemical and immunohistochemical analysis revealed increased Lyn, PDGFR-α, and PDGFR-β expression in cell lines and FFPE original neoplastic tissue compared to healthy prostate tissue. Masitinib exposure increased apoptosis, while the cell counts and cell viability decreased in a dose- and application interval-dependent manner, with increased impact in the 12-h double-dose regimen. These in vitro effects of masitinib in canine prostate cancer and associated metastasis support further in vivo research and modifications of the clinical treatment protocol in future studies.

Piperine analogs arrest c-myc gene leading to downregulation of transcription for targeting cancer

G-quadruplex (G4) structures are considered a promising therapeutic target in cancer. Since Ayurveda, Piperine has been known for its medicinal properties. Piperine shows anticancer properties by stabilizing the G4 motif present upstream of the c-myc gene. This gene belongs to a group of proto-oncogenes, and its aberrant transcription drives tumorigenesis. The transcriptional regulation of the c-myc gene is an interesting approach for anticancer drug design. The present study employed a chemical similarity approach to identify Piperine similar compounds and analyzed their interaction with cancer-associated G-quadruplex motifs. Among all Piperine analogs, PIP-2 exhibited strong selectivity, specificity, and affinity towards c-myc G4 DNA as elaborated through biophysical studies such as fluorescence emission, isothermal calorimetry, and circular dichroism. Moreover, our biophysical observations are supported by molecular dynamics analysis and cellular-based studies. Our study showed that PIP-2 showed higher toxicity against the A549 lung cancer cell line but lower toxicity towards normal HEK 293 cells, indicating increased efficacy of the drug at the cellular level. Biological evaluation assays such as TFP reporter assay, quantitative real-time PCR (qRT- PCR), and western blotting suggest that the Piperine analog-2 (PIP-2) stabilizes the G-quadruplex motif located at the promoter site of c-myc oncogene and downregulates its expression. In conclusion, Piperine analog PIP-2 may be used as anticancer therapeutics as it affects the c-myc oncogene expression via G-quadruplex mediated mechanism.

Disentangling the Structure-Activity Relationships of Naphthalene Diimides as Anticancer G-Quadruplex-Targeting Drugs

In the context of developing efficient anticancer therapies aimed at eradicating any sort of tumors, G-quadruplexes represent excellent targets. Small molecules able to interact with G-quadruplexes can interfere with cell pathways specific of tumors and common to all cancers. Naphthalene diimides (NDIs) are among the most promising, putative anticancer G-quadruplex-targeting drugs, due to their ability to simultaneously target multiple G-quadruplexes and their strong, selective in vitro and in vivo anticancer activity. Here, all the available biophysical, biological, and structural data concerning NDIs targeting G-quadruplexes were systematically analyzed. Structure–activity correlations were obtained by analyzing biophysical data of their interactions with G-quadruplex targets and control duplex structures, in parallel to biological data concerning the antiproliferative activity of NDIs on cancer and normal cells. In addition, NDI binding modes to G-quadruplexes were discussed in consideration of the structures and properties of NDIs by in-depth analysis of the available structural models of G-quadruplex/NDI complexes.

Targeted therapy for upper gastrointestinal tract cancer: current and future prospects

Gastric and oesophageal carcinoma remain major causes of worldwide mortality and morbidity. Despite incredible progress in understanding tumour biology, few targeted treatment options have proved effective in prolonging survival, and adjuvant therapy is largely interchangeable in these carcinomas. Through large-scale sequencing by the Cancer Genome Atlas and the Asian Cancer Research Group, numerous potential molecular targets have been discovered. Of the approved targeted therapies for gastric and oesophageal cancer, pathologists play a role in patient selection for the majority of them. Trastuzumab has been approved as a first-line therapy in conjunction with standard treatment in adenocarcinomas with either 3+ HER2/neu expression by immunohistochemistry or ERBB2 amplification by FISH. PD-L1 immunohistochemistry showing a combined positive score of 1 or greater qualifies patients for third-line pembrolizumab therapy, and identification of microsatellite instability-high carcinomas may qualify patients for second-line pembrolizumab. Ramucirumab, targeting VEGFR2, has also been approved for second-line therapy in gastric carcinoma. Non-surgical therapy for gastrointestinal stromal tumours relies mainly upon tyrosine kinase inhibitors, while new targeted therapy options for neuroendocrine neoplasms have recently emerged. Potential future options for targeted therapy in all these malignancies are being investigated in clinical trials, as this review will discuss.

High expression of G protein subunit gamma 13 is associated with poor prognosis of gastrointestinal stromal tumor

The G protein subunit gamma 13 (GNG13) plays an important role in olfaction, vision, and biological behavior. However, our knowledge of the relationship between GNG13 expression and the clinicopathological features of gastrointestinal tumors is insufficient. Therefore, we used the Oncomine database to evaluate the expression of GNG13 mRNA in gastric cancer, the result showed that there was no significant difference in the expression of GNG13 between gastric cancer and adjacent normal tissues, and GNG13 mRNA expression was assessed in 32 matched pairs of Gastrointestinal adenocarcinoma tissues and adjacent normal tissues as well as 32 matched pairs of gastrointestinal stromal tumor (GIST) and adjacent normal tissues by quantitative reverse transcription-polymerase chain reaction analysis. The results suggested that GNG13 is upregulated in gastrointestinal stromal tumors. Immunohistochemical analysis was used to detect the GNG13 in the tissues of 123 patients with GIST. High cytoplasmic expression of GNG13, which was observed in 65.85 % of GIST patients, significantly correlated with mitotic index(P = 0.036) and tumor size(P = 0.024). Multiple logistic regression analysis showed that the expression of GNG13 was significantly associated with tumor size. Kaplan-Meier analysis indicated that high GNG13 expression was associated with poor prognosis of GIST. Multivariate Cox regression analysis indicated that the expression of GNG13, mitotic index and tumor size were independent adverse prognostic factors of GIST. These findings suggest that GNG13 is associated with the malignant phenotype of GIST and may serve as a marker of poor prognosis.

Potentiation of imatinib by cilostazol in sensitive and resistant gastrointestinal stromal tumor cell lines involves YAP inhibition

Despite the introduction of tyrosine kinase inhibitors, gastrointestinal stromal tumors (GIST) resistance remains a major clinical challenge. We previously identified phosphodiesterase 3A (PDE3A) as a potential therapeutic target expressed in most GIST. The PDE3 inhibitor cilostazol reduced cell viability and synergized with the tyrosine kinase inhibitor imatinib (Gleevec™) in the imatinib-sensitive GIST882 cell line. Here, we found that cilostazol potentiated imatinib also in the imatinib-resistant GIST48 cell line. Cilostazol induced nuclear exclusion, hence inactivation, of the transcriptional co-activator YAP, in a cAMP-independent manner. Verteporfin, a YAP/TEAD interaction inhibitor, reduced by 90% the viability of both GIST882 and GIST48 cells. Our results highlight the potential use of compounds targeting PDE3A or YAP in combined multitherapy to tackle GIST resistance.

New Mass Spectrometric Approaches for the Quantitative Evaluation of Anticancer Drug Levels in Treated Patients

Alternatively to the well-consolidated liquid chromatography coupled to tandem mass spectrometry approach used for the evaluation of anticancer drug concentrations in treated patients, new mass spectrometric methods have been proposed and tested recently. They exhibited faster analysis time and, at first sight, simpler instrumental approaches. However, results obtained by these methods require an in-depth evaluation, because of their strong dependence on the experimental set-up. In this short review, the quantification of irinotecan, sunitinib, and 6-α-hydroxy paclitaxel (the main metabolite of paclitaxel) by laser desorption ionization techniques (matrix-assisted laser desorption/ionization, nanostructure-assisted laser desorption/ionization, and surface-assisted laser desorption/ionization) is reported and discussed, showing the advantages but also the drawbacks of the methods. The matrix-assisted laser desorption/ionization approach led to the most reliable results, and the cross-validation for the quantitative analysis of irinotecan indicates that this method can be fruitfully used for therapeutic drug monitoring and pharmacokinetic studies. Another recently proposed technique, paper spray mass spectrometry, has been tested for the quantitative measurement of imatinib in plasma samples. Even if the approach is, at first sight, really simple, the parameterization of the analytical and instrumental aspects has required many efforts to reach satisfactory results. What it should be expected in the future is the evaluation of these methods, not only in scientific environments dedicated to instrument development, but also in clinical chemistry laboratories, to evaluate their effectiveness and to give new and valid tools for TDM and for other qualitative or quantitative measurements of biomedical interest.

Non-Coding RNAs and Resistance to Anticancer Drugs in Gastrointestinal Tumors

Non-coding RNAs are important regulators of gene expression and transcription. It is well established that impaired non-coding RNA expression especially the one of long non-coding RNAs and microRNAs is involved in a number of pathological conditions including cancer. Non-coding RNAs are responsible for the development of resistance to anticancer treatments as they regulate drug resistance-related genes, affect intracellular drug concentrations, induce alternative signaling pathways, alter drug efficiency via blocking cell cycle regulation, and DNA damage response. Furthermore, they can prevent therapeutic-induced cell death and promote epithelial-mesenchymal transition (EMT) and elicit non-cell autonomous mechanisms of resistance. In this review, we summarize the role of non-coding RNAs for different mechanisms resulting in drug resistance (e.g., drug transport, drug metabolism, cell cycle regulation, regulation of apoptotic pathways, cancer stem cells, and EMT) in the context of gastrointestinal cancers.

Advances and Challenges on Management of Gastrointestinal Stromal Tumors

Gastrointestinal stromal tumors (GISTs) originate from interstitial cells of Cajal and account for over 5,000 newly diagnosed cases in the United States. The discovery of activated KIT and PDGFRA mutations and introduction of imatinib revolutionized the treatment strategy and opened up the new era of target therapy for solid tumors. Although surgery remains the primary modality of treatment for curative purpose, almost half of the patients experienced disease recurrence. Tailoring (neo)-adjuvant treatment with imatinib is ongoing to meet the need for an effective therapy. Currently, two drugs (sunitinib and regorafenib) have obtained Food and Drug Administration approval for GISTs after imatinib failure. However, most of the patients eventually progress due to primary or secondary resistance. Deeper understanding of the molecular mechanisms will guide us to develop personalized strategies in the future. Discussion in this review includes current standard management and the most recent advances and multiple ongoing clinical trials with different approaches. This review will provide further steps to be taken to conquer refractory disease.

Evaluation for therapeutic measures to small gastric stromal tumor: A retrospective study of 90 cases

Surgery and regular follow-up are two main measures for small gastric stromal tumors (sGST) less than 2cm in diameter, while there is no sound evidence to prove which treatment is more beneficial to sGST patients. In this study, we reviewed the clinical and pathological features of patients with sGST receiving surgery and discussed the value of surgical intervention. In all, 90 patients who were diagnosed as sGST(less than 2cm) and accepted surgical treatment were enrolled, correspondently, another 104 patients with GSTs between 2-5cm and 74 patients with GSTs >5cm were collected as Control groups 1 and 2, respectively, and all of them received surgical treatment. Results showed that there were no significant difference among 3 groups in terms of gender, age, clinical features, tumor locations, and mutations of the exon 9 or 11 in C-kit gene, and immunohistochemical results of CD117, CD34, and DOG-1 proteins (P > 0.05). However, we observed growing percentage of medium-/high-risk GSTs and nucleus mitotic counts >5/50 HPF in Control groups (P < 0.05). Patients with sGST were more suitable for minimally invasive procedures than the other 2 groups, with shorter hospital stay (P < 0.05). During the follow-up period (medium 45.4 months), the recurrence rate was also associated with tumor size, which surged from 1.11% in sGST group to 7.69% and 17.56% in Control groups 1 and 2, respectively. In all, we concluded that patients with sGST experienced low proportions of medium-/high-risk tumors; however, they still suffered from potential risk of tumor progression. Due to satisfied surgical outcome, surgical treatment could be suggested for sGST.

Classification of gastrointestinal stromal tumor syndromes

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract, thought to derive from neoplastic outgrowth of the interstitial cells of Cajal. Building on recent advances in recognition, classification and diagnosis, the past two decades have seen a changing paradigm with molecular diagnostics and targeted therapies. KIT and PDGFRA mutations account for 85-90% of GIST carcinogenesis. However, the remaining 10-15% of GISTs, which until recently were called KIT/PDGFRA wild-type GISTs, have been found to have one of the several mutations, including in the SDHA, B, C, D, BRAF and NF1 genes. Though most of such GISTs are sporadic, a number of families with high incidence rates of GISTs and other associated clinical manifestations have been reported and found to harbor germline mutations in KIT, PDGFRA, SDH subunits and NF1 The goal of this review is to describe the mutations, clinical manifestations and therapeutic implications of syndromic and inherited GISTs in light of recent studies of their clinicopathologic range and pathogenesis.

Ileal GIST presenting with bacteremia and liver abscess: A case report and review of literature

INTRODUCTION

Small intestine gastrointestinal stromal tumors can infrequently present with intra-abdominal abscess, perforation, obstruction or fistula. Tumor-small intestine fistula is a rare phenomenon and occurs as a result of GISTs' propensity to cause mucosal ulceration. This allows bacteria from the gut to gain access to the systemic circulation and predisposes the patient to bacteremia and pyogenic liver abscess.

PRESENTATION OF CASE

We present a case of a 63-year-old female whose initial symptoms included fever, nausea, vomiting and right upper quadrant pain. Radiologic studies revealed a liver lesion and an intra-abdominal mass containing oral contrast, suggesting involvement of the gastrointestinal tract. She was found to have a liver abscess, Streptococcus anginosus bacteremia and an ileal GIST that formed a fistula between the tumor and small intestine. We performed a surgical resection of the tumor and percutaneous drainage of the liver abscess. Imatinib was initiated post operatively and she experienced no recurrence, as demonstrated by a surveillance computed tomography scan at 12 months.

CONCLUSION

Findings of a liver lesion in association with a small intestine GIST should raise concern for both metastatic disease and a possible infectious complication such as a pyogenic liver abscess. If a member of the Streptococcus milleri group is isolated in blood cultures, a consideration for gastrointestinal malignancy is imperative. This case report reviews a rare presentation of an ileal GIST with tumor-intestinal fistula, complicated by liver abscess and Streptococcus anginosus bacteremia.

Evidence mapping based on systematic reviews of therapeutic interventions for gastrointestinal stromal tumors (GIST)

Background

Gastrointestinal Stromal Tumours (GISTs) are the most common mesenchymal tumours. Currently, different pharmacological and surgical options are used to treat localised and metastatic GISTs, although this research field is broad and the body of evidence is scattered and expanding. Our objectives are to identify, describe and organise the current available evidence for GIST through an evidence mapping approach.

Methods

We followed the methodology of Global Evidence Mapping (GEM). We searched Pubmed, EMBASE, The Cochrane Library and Epistemonikos in order to identify systematic reviews (SRs) with or without meta-analyses published between 1990 and March 2016. Two authors assessed eligibility and extracted data. Methodological quality of the included systematic reviews was assessed using AMSTAR. We organised the results according to identified PICO questions and presented the evidence map in tables and a bubble plot.

Results

A total of 17 SRs met eligibility criteria. These reviews included 66 individual studies, of which three quarters were either observational or uncontrolled clinical trials. Overall, the quality of the included SRs was moderate or high. In total, we extracted 14 PICO questions from them and the corresponding results mostly favoured the intervention arm.

Conclusions

The most common type of study used to evaluate therapeutic interventions in GIST sarcomas has been non-experimental studies. However, the majority of the interventions are reported as beneficial or probably beneficial by the respective authors of SRs. The evidence mapping is a useful and reliable methodology to identify and present the existing evidence about therapeutic interventions.

Electronic supplementary material

The online version of this article (doi:10.1186/s12874-017-0402-9) contains supplementary material, which is available to authorized users.

[Clinical and morphological characteristics of gastrointestinal stromal tumors]

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. Despite this, GISTS comprise about 2% in the structure of digestive tract cancers. They are usually localized in the stomach; however, they can be found in the small intestine and more rarely in the colon and esophagus. Although approximately 70% of the GISTs consist predominantly of spindle cells; the epithelioid cell tumors represent 20% of cases; there are also mixed variants. This variability in the morphological structure of GISTs complicates their diagnosis.

Genetic progression in gastrointestinal stromal tumors: mechanisms and molecular interventions

Gastrointestinal stromal tumors (GISTs) are the most common sarcomas in humans. Constitutively activating mutations in the KIT or PDGFRA receptor tyrosine kinases are the initiating oncogenic events. Most metastatic GISTs respond dramatically to therapies with KIT/PDGFRA inhibitors. Asymptomatic and mitotically-inactive KIT/PDGFRA-mutant "microGISTs" are found in one third of adults, but most of these small tumors never progress to malignancy, underscoring that a progression of oncogenic mutations is required. Recent studies have identified key genomic abnormalities in GIST progression. Novel insights into the genetic progression of GISTs are shedding new light on therapeutic innovations.

Subepithelial rectal gastrointestinal stromal tumor - the use of endoscopic ultrasound-guided fine needle aspiration to establish a definitive cytological diagnosis: a case report

Background

Gastrointestinal stromal tumors are the most common mesenchymal neoplasms affecting the gastrointestinal tract. The stomach is the most common location to be affected, and the rectum one of the rarest, but the whole gastrointestinal tract remains susceptible. Gastrointestinal stromal tumors account for only 0.1% of rectal tumors. Currently, endoscopic ultrasound plays an essential role in the diagnostic process of gastrointestinal stromal tumors, especially when the affected sites have a worse outcome and higher morbidity rates.

Case presentation

We describe the case of a 68-year-old white Japanese man with a history of long-term mild rectal pain and tenesmus. A digital rectal examination revealed a right palpable solid mass ranging from 3 to 7 cm from his anal verge. A colonoscopy was performed and showed a 5 cm elevated lesion covered by normal mucosa, located 4 cm above the pectineal line. Endoscopic ultrasound confirmed the diagnosis of a homogeneous hypoechoic mass with areas of necrosis as a rectal subepithelial lesion originating at the fourth layer (muscularis propria). He then underwent endoscopic ultrasound-guided fine needle aspiration of the lesion, followed by cytological and immunohistochemistry evaluation. The evaluation showed spindle and epithelioid cells of variable sizes, in fascicles separated by stroma, which reacted firmly and consistently to CD117/c-kit and CD34, and negative to desmin and S-100 protein. There was weak staining for nuclear Ki-67 in the tumor cells. A diagnosis of rectal gastrointestinal stromal tumor was confirmed. After a multidisciplinary meeting, an abdominoperineal resection of his rectum was performed. The pathology of the specimen confirmed the diagnosis of rectal gastrointestinal stromal tumor. He is now asymptomatic after 3 months’ follow-up and is on adjuvant therapy with a tyrosine-kinase inhibitor.

Conclusions

Gastrointestinal stromal tumors are rare tumors, and among the variety of primary location sites, the rectum is one of the rarest. The localization of this type of tumor has worse outcomes and higher morbidity rates. We report this rare case to emphasize the need for precise diagnosis and the important role of endoscopic ultrasound-guided fine needle aspiration in such situations.

Role of LKB1 in proliferation and apoptosis of gastric cancer cells

AIM: To explore the role of LKB1 in gastric cancer cells and the related mechanism.

METHODS: Real-time PCR and Western blot were used to detect the expression of LKB1 in SGC7901 cells carrying LKB1 expression vector or siRNA against LKB1. Flow cytometry was used to detect the apoptosis of SGC7901 cells after LKB1 overexpression or knockdown. Reactive oxygen detection kits were applied to detect the impact of LKB1 on ROS production. MTT method was used to determine intracellular ROS production after NAC inhibition. Western blot was used to detect the expression of apoptosis related proteins in SGC7901 cells after LKB1 overexpression or knockdown.

RESULTS: LKB1 expression was efficiently enhanced or silenced by LKB1 expression vector or siRNA against LKB1, respectively. The number of SGC7901 cells decreased as its proliferation rate decreased and apoptosis rate increased (3.54% vs 1.29%). Intracellular ROS production was increased but blunted by the use of NAC. The apoptosis of SGC7901 cells was significantly reduced following the inhibition of intracellular ROS, but the siRNA transfected group exhibited an opposite trend. Western blot analysis showed that LKB1 overexpression up-regulated the expression of cleaved Caspase3 in SGC7901 cells significantly (about 3.12 times), compared with control cells, but the expression of cleaved Caspase3 in the siRNA transfected group was decreased.

CONCLUSION: LKB1 raises the production of ROS and up-regulates the expression of cleaved Caspase3 to promote gastric cancer cell apoptosis. Hence, LKB1 plays an important role in the development of gastric cancer and it may be a valuable target for chemotherapy of gastric cancer.

Field-assisted paper spray mass spectrometry for the quantitative evaluation of imatinib levels in plasma

Drug levels in patients' bloodstreams vary among individuals and consequently therapeutic drug monitoring (TDM) is fundamental to controlling the effective therapeutic range. For TDM purposes, different analytical approaches have been used, mainly based on immunoassay, liquid chromatography- ultraviolet, liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods. More recently a matrix-assisted laser desorption/ionisation method has been proposed for the determination of irinotecan levels in the plasma of subjects under therapy and this method has been cross- validated by comparison with data achieved by LC-MS/MS. However, to reach an effective point-of-care monitoring of plasma drug concentrations, a TDM platform technology for fast, accurate, low-cost assays is required. In this frame, recently the use of paper spray mass spectrometry, which is becoming a popular and widely employed MS method, has been proposed. In this paper we report the results obtained by the development of a paper spray-based method for quantitative analysis in plasma samples of imatinib, a new generation of anticancer drug. Preliminary experiments showed that poor sensitivity, reproducibility and linear response were obtained by the "classical" paper spray set-up. In order to achieve better results, it was thought of interest to operate in presence of a higher and more homogeneous electrical field. For this aim, a stainless steel needle connected with the high voltage power supply was mounted below the paper triangle. Furthermore, in order to obtain valid quantitative data, we analysed the role of the different equilibria participating to the phenomena occurring in paper spray experiments, depending either on instrumental parameters or on the chemical nature of analyte and solvents. A calibration curve was obtained by spiking plasma samples containing different amounts of imatinib (1) with known amounts of deuterated imatinib (1_d3) as internal standard, with molar ratios [1]/[1_d3] in the range 0.00-2.00. A quite good linearity was obtained (R² = 0.975) and some experiments performed on spiked plasma samples with known amounts of 1 confirmed the validity of this method.