Gastrointestinal stromal tumor: an ultrastructural investigation on regional differences with considerations on their histogenesis

Fibrinogen-like protein 2 in gastrointestinal stromal tumour

Gastrointestinal stromal tumour (GIST), the most common sarcoma of the gastrointestinal tract, can be treated effectively with tyrosine kinase inhibitors, such as imatinib. Cancer immune therapy has limited efficacy, and little is known about the immune suppressive factors in GISTs. Fibrinogen‐like protein 2 (FGL2) is expressed either as a membrane‐associated protein or as a secreted soluble protein that has immune suppressive functions. We found that GISTs expressed FGL2 mRNA highly compared to other types of cancer in a large human cancer transcriptome database. GIST expressed FGL2 frequently also when studied using immunohistochemistry in two large clinical series, where 333 (78%) out of the 425 GISTs were FGL2 positive. The interstitial cells of Cajal, from which GISTs may originate, expressed FGL2. FGL2 expression was associated with small GIST size, low mitotic counts and low tumour‐infiltrating lymphocyte (TIL) counts. Patients whose GIST expressed FGL2 had better recurrence‐free survival than patients whose GIST lacked expression. Imatinib upregulated FGL2 in GIST cell lines, and the patients with FGL2‐negative GIST appeared to benefit most from long duration of adjuvant imatinib. We conclude that GISTs express FGL2 frequently and that FGL2 expression is associated with low TIL counts and favourable survival outcomes.

The Incidence of Gastrointestinal Stromal Tumors in Obese Patients—A Large Single Center Experience

Background and Objectives: Gastrointestinal stromal tumors (GISTs) are rare mesenchymal neoplasms located mainly in the fundus (60–70%). The incidence of GIST is approximately 10 per million population per year in Europe, with a peak incidence at the age of 63. Recent studies suggest that morbidly obese patients have a higher incidence of GIST than the general population. The aim of this study was to analyze the incidence of GIST in patients undergoing laparoscopic sleeve gastrectomy (LSG) in our department. Materials and Methods: this paper present the retrospective study of prospectively collected data of 1564 patients who underwent LSG in a single large bariatric center from October 2013 to September 2021. After surgery, each sample of the resected stomach was sent for histopathological examination. For the analysis, we included patients diagnosed with GIST intraoperatively or postoperatively. Results: GISTs were found in five patients (0.31%). There were three men and two women. The mean age was 50.2 (range 32–63 ± 11.8) and the mean preoperative body mass index was 43.3 kg/m² (40–49.4 ± 3.2). In four cases, GISTs were found in the fundus (80%), and in one in the pylorus (20%). None of the tumors were larger than 7 mm in diameter and all were diagnosed as a very low-risk category. No adjuvant treatment was required. All patients achieved good or satisfactory bariatric and metabolic results. Conclusions: The incidence of GIST in our study was estimated at 0.31%. All patients had a very low-risk GIST and no recurrence until follow-up. Recent literature suggests that the risk of GIST is higher in the obese population, and therefore surgeons should be aware of the risk of incidental GIST during LSG.

Clinical features of multiple gastrointestinal stromal tumors: A pooling analysis combined with evidence and gap map

BACKGROUND

Multiple gastrointestinal stromal tumors (MGISTs) are a very rare type of gastrointestinal stromal tumor (GIST) and are usually observed in syndrome.

AIM

The paper aimed to describe the clinical and oncological features of MGISTs and to offer evidence for the diagnosis and treatment.

METHODS

Data of consecutive patients with MGISTs who were diagnosed at Peking University People’s Hospital (PKUPH) from 2008 to 2019 were retrospectively evaluated. Further, a literature search was conducted by retrieving data from PubMed, EMBASE, and the Cochrane library databases from inception up to November 30, 2019.

RESULTS

In all, 12 patients were diagnosed with MGISTs at PKUPH, and 43 published records were ultimately included following the literature review. Combined analysis of the whole individual patient data showed that female (59.30%), young (14.45%), and syndromic GIST (63.95%) patients comprised a large proportion of the total patient population. Tumors were mainly located in the small intestine (58.92%), and both CD117 and CD34 were generally positive. After a mean 78.32-mo follow-up, the estimated median overall survival duration (11.5 years) was similar to single GISTs, but recurrence-free survival was relatively poorer.

CONCLUSION

The clinical and oncological features are potentially different between MGISTs and single GIST. Further studies are needed to explore appropriate surgical approach and adjuvant therapy.

Telocytes in the Normal and Pathological Peripheral Nervous System

We studied telocytes/CD34+ stromal cells in the normal and pathological peripheral nervous system (PNS), for which we reviewed the literature and contributed our observations under light and electron microscopy in this field. We consider the following aspects: (A) general characteristics of telocytes and the terminology used for these cells (e.g., endoneurial stromal cells) in PNS; (B) the presence, characteristics and arrangement of telocytes in the normal PNS, including (i) nerve epi-perineurium and endoneurium (e.g., telopodes extending into the endoneurial space); (ii) sensory nerve endings (e.g., Meissner and Pacinian corpuscles, and neuromuscular spindles); (iii) ganglia; and (iv) the intestinal autonomic nervous system; (C) the telocytes in the pathologic PNS, encompassing (i) hyperplastic neurogenic processes (neurogenic hyperplasia of the appendix and gallbladder), highly demonstrative of telocyte characteristics and relations, (ii) PNS tumours, such as neurofibroma, schwannoma, granular cell tumour and nerve sheath myxoma, and interstitial cell of Cajal-related gastrointestinal stromal tumour (GIST), (iii) tumour-invaded nerves and (iv) traumatic, metabolic, degenerative or genetic neuropathies, in which there are fewer studies on telocytes, e.g., neuroinflammation and nerves in undescended testicles (cryptorchidism), Klinefelter syndrome, crush injury, mucopolysaccharidosis II (Hunter’s syndrome) and Charcot–Marie–Tooth disease.

Bariatric surgery and incidental gastrointestinal stromal tumors - a single-center study: VSJ Competition, 1st place

INTRODUCTION

Gastrointestinal stromal tumors (GISTs), originating from Cajal cells, are most commonly located in the stomach; therefore they can be found in the specimens excised during bariatric operations. The global prevalence of GISTs is about 130 cases per million population. Morbidity differs depending on geographical latitude. Although surgery is the treatment of choice for GISTs, 40-50% of patients after radical surgical treatment will have a relapse or metastases.

AIM

To analyze the incidence of GISTs in patients undergoing bariatric surgery and to verify whether an operation performed according to the bariatric protocol is oncologically radical in case of GIST.

MATERIAL AND METHODS

A single-center retrospective study. The study group comprised 1252 obese patients qualified for bariatric procedures, with no upper gastrointestinal tract neoplasms found during preoperative diagnostic examinations. In case of suspicious macroscopic pathologies (n = 81) present during the operation, tissue specimens underwent histopathological examination with further investigation performed if GISTs were found, including tumor size and localization, mitotic index and immunohistochemical analysis.

RESULTS

Gastrointestinal stromal tumors were found in 16 cases, and benign tumors of various histological origin in 33 cases. All cases of GIST found came from stomach specimens, 7 from the gastric corpus vs. 9 from the fundus. Fourteen GISTs were found during laparoscopic sleeve gastrectomies (LSGs) vs. 2 during laparoscopic Roux-en-Y gastric bypasses (LRYGBs).

CONCLUSIONS

In case of incidental findings of GISTs during bariatric surgery, tumor resection with negative margins of incision may be considered as complete oncological treatment if there was very low/low risk stratification of GIST's recurrence after surgery.

Orai1 mediates tumor-promoting store-operated Ca2+ entry in human gastrointestinal stromal tumors via c-KIT and the extracellular signal-regulated kinase pathway

Gastrointestinal stromal tumors originate from interstitial cells of Cajal, the pacemaker cells of the gut. Ca²⁺ regulates the pacemaker activity of interstitial cells of Cajal. Store-operated Ca²⁺ entry mediates the majority of Ca²⁺ entry in most cancer cells and may be a factor in regulating intracellular Ca²⁺ in interstitial cells of Cajal and gastrointestinal stromal tumors. Therefore, a blockade of this mechanism may affect the progression of gastrointestinal stromal tumors. Orai1 is the pore subunit of store-operated Ca²⁺ channels. Here, we reported that Orai1 was overexpressed in gastrointestinal stromal tumor tissues and was positively correlated with a high-risk grade in gastrointestinal stromal tumor patients. Furthermore, upon Orai1 silencing, the functional store-operated Ca²⁺ entry in gastrointestinal stromal tumor cells was decreased, indicating that the function of store-operated Ca²⁺ entry was mediated by Orai1. Inhibition of Orai1-mediated store-operated Ca²⁺ entry by Orai1 silencing or store-operated Ca²⁺ entry blockers (SKF-96365 and 2-aminoethyl diphenylborate) induced obvious cell proliferation suppression, cell-cycle distribution, and apoptosis stimulation in GIST-T1 cells. Conversely, Orai1 overexpression increased store-operated Ca²⁺ entry and cell proliferation in GIST882 cells. In addition, we found that activation of c-KIT and the extracellular signal-regulated kinase pathway participated in the oncogenic functions of Orai1-mediated store-operated Ca²⁺ entry in gastrointestinal stromal tumor cells. These results revealed that Orai1-mediated store-operated Ca²⁺ entry is critical for gastrointestinal stromal tumor cell proliferation via c-KIT and ERK signaling pathway activation. Orai1-mediated store-operated Ca²⁺ entry plays an oncogenic role and may be a novel prognostic factor and therapeutic target for patients with gastrointestinal stromal tumors.

Clinical significance of IGF1R gene expression in patients with Stage II/III gastric cancer who receive curative surgery and adjuvant chemotherapy with S-1

PURPOSE

Curative resection and adjuvant chemotherapy is the standard treatment for Stage II/III gastric cancer, and S-1 is widely used for adjuvant chemotherapy. The type 1 insulin-like growth factor receptor (IGF1R) is involved in cell proliferation and prevention of apoptosis in many tumors. We evaluated the relative expression of the IGF1R gene to determine whether such expression correlates with outcomes in patients with Stage II/III gastric cancer.

METHODS

We measured the expression levels of the IGF1R gene in specimens of cancer and adjacent normal mucosa obtained from 134 patients with Stage II/III gastric cancer who received curative resection and adjuvant chemotherapy with S-1. We then evaluated whether the IGF1R gene expression levels correlate with clinicopathological characteristics and outcomes.

RESULTS

IGF1R mRNA expression levels tended to be higher in cancer tissue than in the normal adjacent mucosa (P = 0.078). Multivariate analysis showed that high IGF1R gene expression was a significant independent predictor of poor survival in Stage II/III gastric cancer after curative resection and adjuvant chemotherapy with S-1 (HR 3.681, P = 0.007). The overall survival rate was significantly lower in patients with high IGF1R gene expression than in those with low expression (P = 0.012).

CONCLUSIONS

IGF1R overexpression is considered a useful independent predictor of outcomes in Stage II/III gastric cancer after curative resection and adjuvant chemotherapy with S-1.

Gastrointestinal stromal tumour

Gastrointestinal stromal tumours (GISTs) are mesenchymal neoplasms that arise in the gastrointestinal tract, usually in the stomach or the small intestine and rarely elsewhere in the abdomen. They can occur at any age, the median age being 60-65 years, and typically cause bleeding, anaemia, and pain. GISTs have variable malignant potential, ranging from small lesions with a benign behaviour to fatal sarcomas. Most tumours stain positively for the mast/stem cell growth factor receptor KIT and anoctamin 1 and harbour a kinase-activating mutation in either KIT or PDGFRA. Tumours without such mutations could have alterations in genes of the succinate dehydrogenase complex or in BRAF, or rarely RAS family genes. About 60% of patients are cured by surgery. Adjuvant treatment with imatinib is recommended for patients with a substantial risk of recurrence, if the tumour has an imatinib-sensitive mutation. Tyrosine kinase inhibitors substantially improve survival in advanced disease, but secondary drug resistance is common.

Primary cilia in gastric gastrointestinal stromal tumours (GISTs): an ultrastructural study

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal (non-epithelial) neoplasms of the human gastrointestinal (GI) tract. They are thought to derive from interstitial cells of Cajal (ICCs) or an ICC progenitor based on immunophenotypical and ultrastructural similarities. Because ICCs show primary cilium, our hypothesis is based on the possibility that some of these neoplastic cells could also present it. To determine this, an exhaustive ultrastructural study has been developed on four gastric GISTs. Previous studies had demonstrated considerable variability in tumour cells with two dominating phenotypes, spindly and epithelioid. In addition to these two types, we have found another cell type reminiscent of adult ICCs with a voluminous nucleus surrounded by narrow perinuclear cytoplasm with long slender cytoplasmic processes. We have also noted the presence of small undifferentiated cells. In this study, we report for the first time the presence of primary cilia (PCs) in spindle and epithelioid tumour cells, an ultrastructural feature we consider of special interest that has hitherto been ignored in the literature dealing with the ultrastructure of GISTs. We also point out the frequent occurrence of multivesicular bodies (MVBs). The ultrastructural findings described in gastric GISTs in this study appear to be relevant considering the critical roles played by PCs and MVBs recently demonstrated in tumourigenic processes.

Succinate dehydrogenase mutation underlies global epigenomic divergence in gastrointestinal stromal tumor

Gastrointestinal stromal tumors (GIST) harbor driver mutations of signal transduction kinases such as KIT, or, alternatively, manifest loss-of-function defects in the mitochondrial succinate dehydrogenase (SDH) complex, a component of the Krebs cycle and electron transport chain. We have uncovered a striking divergence between the DNA methylation profiles of SDH-deficient GIST (n = 24) versus KIT tyrosine kinase pathway-mutated GIST (n = 39). Infinium 450K methylation array analysis of formalin-fixed paraffin-embedded tissues disclosed an order of magnitude greater genomic hypermethylation relative to SDH-deficient GIST versus the KIT-mutant group (84.9 K vs. 8.4 K targets). Epigenomic divergence was further found among SDH-mutant paraganglioma/pheochromocytoma (n = 29), a developmentally distinct SDH-deficient tumor system. Comparison of SDH-mutant GIST with isocitrate dehydrogenase-mutant glioma, another Krebs cycle-defective tumor type, revealed comparable measures of global hypo- and hypermethylation. These data expose a vital connection between succinate metabolism and genomic DNA methylation during tumorigenesis, and generally implicate the mitochondrial Krebs cycle in nuclear epigenomic maintenance.

Frequency, phenotype, and genotype of minute gastrointestinal stromal tumors in the stomach: an autopsy study

Gastrointestinal stromal tumors are the most common mesenchymal tumors of the human digestive tract. Up to 85% of these tumors show somatic gain-of-function mutation of the receptor tyrosine kinase c-KIT gene. A recent study has shown a high frequency (22.5%) of minute gastrointestinal stromal tumors in stomachs examined during routine autopsies. The aims of our study were to confirm the previously reported incidence of gastric gastrointestinal stromal tumors in routine autopsies and to investigate their molecular alterations. Gastrointestinal stromal tumors were collected prospectively from 578 autopsies over an 18-month period. After recording the size and location of each lesion, representative tissue samples were processed for hematoxylin and eosin staining and immunohistochemically stained for CD117 and CD34. Microdissected DNA from all identified gastrointestinal stromal tumors was studied for c-KIT and platelet-derived growth factor receptor α mutations. We identified 17 gastrointestinal stromal tumors in 578 consecutive autopsies (2.9%) located in the gastric body (47%) and fundus (47%). One tumor location was not recorded. All tumors were immunohistochemically positive for CD117 and CD34. DNA analysis showed c-KIT mutations in 11 cases. One platelet-derived growth factor receptor α mutation was found. The incidence of gastric minute gastrointestinal stromal tumors (2.9%) is higher than the reported clinical incidence. All are benign tumors, and most, including minute tumors, contain c-KIT mutations. This finding highlights the fact that c-KIT mutations are an early event in the evolution of gastrointestinal stromal tumors but are not sufficient per se for clinically relevant disease.

Differential expression of metallothionein in gastrointestinal stromal tumors and gastric carcinomas

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors that account for about 2% of gastric tumors. Metallothioneins (MTs) are multifunctional proteins associated with carcinogenesis and known to be coded by 10 functional MT genes. This study evaluated MT mRNA and protein expression in GISTs and compared the expression levels with gastric carcinomas. An immunohistochemical study of MT protein expression was performed in 15 GISTs (specifically located in the stomach) and 38 early stage gastric carcinomas. The percentage of cells stained and intensity of staining were determined. MT-2A mRNA expression was investigated in 6 GISTs and 6 early stage gastric carcinoma patients. All GISTs displayed positive nuclear immunostaining, with most GISTs having predominantly mildly stained nuclei (93.3%). On the other hand, 37 out of 38 gastric carcinoma cases were positively stained for nuclear MT with 24 cases (63.2%) exhibiting predominantly mild nuclear staining, 7 cases (18.4%) moderate nuclear staining, and 6 cases (15.8%) strong nuclear staining. Nuclear MT expression was found to be significantly lower in GIST samples when compared with gastric carcinoma tissues based on the percentage stained and immunoreactive score. We then established that the MT-2A gene transcript was the most abundant MT isoform in MKN28 gastric cancer cells and analyzed its expression in GIST and gastric carcinoma tissues. We found that GISTs had significantly lower MT-2A mRNA levels than gastric carcinoma tissues. Lower MT-2A gene expression and nuclear MT protein expression in GISTs when compared with gastric carcinomas may reflect their different underlying biology and divergent histogenesis.

Stem cells and colon cancer: the questionable cancer stem cell hypothesis

The fine-tuning between cell proliferation and differentiation of self-renewing stem cells and pluripotent progenitors in gastric glands and colon epithelial crypts is coordinated by the mechanisms that regulate colon epithelial cell migration and guidance along the crypt axis. This leads to the acquisition of specialized cellular functions and the exfoliation of desquamated senescent and apoptotic epithelial cells at the apical mucosa interface with the gut lumen. Self-renewing stem cells and pluripotent progenitors are involved in the clonal and polyclonal growth of digestive tumors. Several lines of evidence support the existence of a subpopulation of cancer cells with stem cell-like (SCL) phenotypes in solid tumors of breast and digestive system. Consistently, epithelial cancer cell lines in long-term culture are phenotypically and functionally heterogeneous. It is suggested that only a small proportion of transformed cells are clonogenic in vivo and ex vivo to form colonies and to initiate tumor growth in immunodeficient mice. A discrete subpopulation of tumor -initiating SCL cancer cells are highly competent to survive, propagate and spread through the invasive and metastatic cascade. A better understanding of the mechanisms driving the plasticity and pluripotency of stem cells, their derived progenitors and SCL colon cancer initiating cells during tumor progression will open new avenues for the early detection and treatment of local and distant tumors of the digestive tract.