Loss of p16 Protein Defines High-Risk Patients with Gastrointestinal Stromal Tumors: A Tissue Microarray Study

Expression of p16 Tumor Suppressor Protein in Malignant Ovarian Germ Cell Tumors; Immunohistochemical Study

BACKGROUND

Malignant ovarian germ cell tumors represent small percentage of malignant ovarian neoplasms but they affect significantly young age group.

AIM OF THE STUDY

To investigate the immunohistochemical expression of p16 tumor suppressor protein in malignant ovarian germ cell tumors.

MATERIALS AND METHODS

Twenty-two malignant ovarian germ cell tumors (five dysgerminoma, eight immature teratoma, and nine yolk sac tumors), twenty mature cystic teratoma tumors and twenty normal ovarian tissue were immunohistochemically stained with p16 monoclonal antibody. Ki67 immunohistochemical staining was done for malignant ovarian germ cell tumors to assess proliferation.

RESULTS

We found that p16 tumor suppressor protein is overexpressed in all malignant ovarian germ cell tumors in both nuclear and cytoplasmic locations compared to control and to mature cystic teratoma (p-value <0.001). Cytoplasmic p16 expression was significantly correlated to Ki67 proliferation index in malignant ovarian germ cell tumors (p-value = 0.033, r = 0.445).

CONCLUSION

Overexpression of p16 in malignant ovarian germ cell tumors denotes that dysfunction of the cyclin dependent kinase pathway is involved in tumorigenesis of malignant ovarian germ cell tumors.

Genetic alterations in cell cycle regulation-associated genes may promote primary progression of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are one of the most common mesenchymal tumor types and usually contain KIT or PDGFRA mutations. GISTs with concomitant low- and high-grade components are seen in clinical practice. Herein, we retrospectively analyzed the histological characteristics and immunohistochemical results of 22 GIST cases with concomitant low- and high-grade tumors. Whole-exome sequencing (WES) was performed on ten pairs of high-grade GIST specimens and matched low-grade samples. Differential oncogenes mutated only in high-grade GISTs were identified, which were confirmed by Sanger sequencing. Fluorescence in situ hybridization was employed to detect MYC copy number variation. High-grade GISTs were more likely to have lower CD34 expression and a higher Ki-67 proliferation index compared to the matched low-grade tumors. WES identified 30 differential cancer-associated genes mutated only in high-grade GISTs; Sanger sequencing confirmed ten relevant differential oncogenic mutations in nine genes (MGA, ARID1A, LATS2, MAX, PIK3CA, RB1, RPS6KB2, SDHA, and SETD2). Two patients had MGA mutations, whereas other gene mutations occurred in only one patient. Most of the differential cancer-associated genes are mainly involved in cell cycle control. MYC copy number gain was a common genetic variation. High-grade GISTs revealed more MYC copy number gains than matched low-grade tumors, and low-grade GISTs with coexisting high-grade components showed more MYC copy number gains than pure low-grade GISTs. Moreover, MYC copy number gain was positively correlated with the mitotic index and Ki-67 proliferation index. Alterations in cell cycle regulation-associated genes, such as genetic mutations and MYC copy number gain, may promote primary progression from low-grade GISTs to high-grade tumors by regulating tumor cell proliferation.

Common Secondary Genomic Variants Associated With Advanced Epithelioid Hemangioendothelioma

IMPORTANCE

Epithelioid hemangioendothelioma (EHE) is a rare, malignant vascular sarcoma characterized in most cases by a WWTR1-CAMTA1 fusion. The clinical course of EHE exhibits a dual nature. The condition is often indolent but can rapidly grow and metastasize unpredictably. No biomarkers to date are available to predict this phenotype. The hypothesis of this study was that better defining the genomic landscape of EHE using next-generation sequencing could offer additional therapies and insight into clinical outcomes.

OBJECTIVE

To characterize secondary EHE genomic alterations and their association with clinical outcomes.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter, cross-sectional, retrospective study of next-generation sequencing results collected from participants diagnosed with EHE. Data were abstracted between May 1, 2013, and May 31, 2019. This analysis was conducted from January through June 2019. Summary genomic data were provided by commercial genomic testing companies.

MAIN OUTCOMES AND MEASURES

Presence or absence of secondary pathogenic genomic variants and their association with disease stage and clinical features.

RESULTS

A total of 49 participants with EHE were assessed for the presence or absence of secondary genomic variants. Of these, 32 (65.3%) were female; the mean (SD) age at diagnosis was 49.9 (18.3) years (range, 11-81 years). In all, 46 participants (93.9%) had confirmed WWTR1-CAMTA1 fusion; 26 participants (57.1%) exhibited a pathogenic genomic variant secondary to the WWTR1-CAMTA1 fusion; and 9 participants (18.4%) exhibited potentially targetable genomic variants. Commonly altered genes included CDKN2A/B, RB1, APC, and FANCA. Participants older than 45 years at diagnosis had an increased prevalence of secondary genomic variants that was not statistically significant (65.6% vs 38.5%; difference, 27.1%; 95% CI, -3.5% to 58.0%; P = .16) and were more likely to have a clinically targetable variant (28.1% vs 0%; difference, 28.1%; 95% CI, 11.2%-40.2%; P = .03). In 14 participants with clinical data available, those with stage III/IV EHE were more likely to exhibit a secondary pathogenic genomic variant (80% vs 0%; difference, 80%; 95% CI, 55.2%-100%; P = .006). Participants with stage III/IV EHE were diagnosed at an older age (mean [SD] age, 54.6 [14.1] years vs 31.7 [16.0] years; P = .05) and had elevated WWTR1-CAMTA1 fusion expression that was not statistically significant (mean [SD] expression, 677 [706] copies vs 231 [213] copies; P = .20).

CONCLUSIONS AND RELEVANCE

Although EHE exhibits few secondary genomic variants, presence of key secondary variants may be prognostic for aggressive EHE. Further research is needed to confirm this finding and determine whether more intensive upfront treatment is necessary for these patients.

Clinicopathologic Characteristics and Optimal Surgical Treatment of Duodenal Gastrointestinal Stromal Tumor

BACKGROUND

The clinicopathologic characteristics of duodenal gastrointestinal stromal tumor (GIST) were unclear and the optimal surgical procedure for duodenal GIST remains poorly defined. We aimed to analyze clinicopathological characteristics, survival outcomes based on the surgical procedure, and recommend optimal surgical treatment for duodenal GIST.

METHODS

From July 2000 to April 2017, 118 patients with localized duodenal GIST underwent curative surgical resection at a single institution. We retrospectively reviewed the clinicopathological characteristics and survival outcomes.

RESULTS

The 5-year overall survival (OS) and disease-free survival (DFS) rates were 94.9 and 79.2%, respectively. On multivariate analysis, the mitotic count was a statistically significant prognostic factor for DFS. Limited resection (LR) was performed in 20 patients with GIST in the first or fourth portion of the duodenum. Both LR and pancreaticoduodenectomy (PD) were performed in 98 patients with GIST in second or third portion of the duodenum. The patients in the LR group had less late complications than in the PD group and no postoperative newly developed diabetes mellitus. The minimally invasive LR (MI-LR) group had a shorter duration of surgery and shorter length of postoperative hospital stay.

CONCLUSION

LR is a feasible and effective surgical treatment for patients with small-sized and antimesenteric-sided duodenal GIST in terms of late complications and postoperative diabetic complications. MI-LR has better perioperative outcomes than open LR. Therefore, we should consider MI-LR as an optimal surgical treatment for selected patients with duodenal GIST.

Molecular biomarkers for prognosis of gastrointestinal stromal tumor

Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. However, the development of molecular markers, especially circulating biomarkers, remains largely undone for the prognosis of GIST. We discussed the clinical-pathological characteristics of GIST and identified potential biomarkers for guidance of therapy and prognosis of GIST. Around 90% of GISTs contain mutations in KIT or PDGFRA and the remaining 10% of GISTs are wild-type. Recent studies have indicated that various DNAs and miRNAs could serve as potential biomarkers for prognosis of GIST, including KIT, PDGFRA, other DNAs (such as BRAF, SDH, SETD2 and ROR2), and microRNAs (miRNAs). The pressing need and challenges in the development of circulating prognostic biomarkers for GIST are also discussed. Although challenges remain, DNAs and miRNAs are promising circulating biomarkers for surveillance and prognosis of GIST. Advances in clarification of aberrant molecular alterations may open new avenues for exploration of reliable and robust biomarkers to improve the management of GIST.

Stromal p16 expression is significantly increased in malignant ovarian neoplasms

Alterations in p16 protein expression have been reported to be associated with tumor development and progression. However, p16 expression status in the peritumoral stroma has been rarely investigated. We investigated the stromal p16 expression in ovarian neoplasms using immunohistochemistry, and differences in the expression status depending on the degree of malignancy and histological type were analyzed. This study included 24, 21, and 46 cases of benign, borderline, and malignant ovarian lesions, respectively, of which 29, 25, and 32 cases were serous, mucinous, and endometriosis-associated lesions. Most benign lesions showed negative or weak expression, whereas borderline lesions showed focal, moderate expression. Malignant lesions showed markedly elevated stromal p16 expression compared with benign or borderline lesions. There were significant differences in stromal p16 expression between benign and borderline lesions (P < 0.001) and between borderline and malignant lesions (P < 0.001). These significances remained when analysis was performed based on lesion classification as serous, mucinous, and endometriosis-associated. In contrast, differences in stromal p16 expression among the histological types were not significant. Stromal p16 expression in ovarian neoplasms was absent or weak in benign and focal, moderate in borderline lesions, whereas malignant lesions exhibited diffuse, moderate-to-strong p16 immunoreactivity. Our observations suggest that stromal p16 expression is involved in the development of ovarian carcinoma. Further studies are necessary to confirm our preliminary results.

Stromal p16 expression is significantly increased in endometrial carcinoma

p16 is a negative regulator of cell proliferation and is considered a tumor suppressor protein. Alterations in p16 protein expression are associated with tumor development and progression. However, the p16 expression status in the peritumoral stroma has not been investigated in the endometrium. Therefore, we evaluated stromal p16 expression in different types of endometrial lesions using immunohistochemistry. Differences in the p16 expression status according to the degree of malignancy and histological type were analyzed. This study included 62, 26, and 36 cases of benign, precancerous, and malignant endometrial lesions, respectively. Most benign lesions showed negative or weak expression, whereas precancerous lesions showed a variable degree of staining proportion and intensity. Atypical hyperplasia/endometrial intraepithelial neoplasia (AH/EIN) and serous endometrial intraepithelial carcinoma (SEIC) had significantly higher stromal p16 expression levels than benign lesions. Endometrioid carcinoma (EC), serous carcinoma (SC), and carcinosarcoma showed significantly elevated stromal p16 expression levels compared with benign and precancerous lesions. In addition, there were significant differences in stromal p16 expression between AH/EIN and SEIC and between EC and SC. In contrast, differences in stromal p16 expression among nonpathological endometrium, atrophic endometrium, endometrial polyp, and hyperplasia without atypia were not statistically significant. Our observations suggest that stromal p16 expression is involved in the development and progression of endometrial carcinoma, and raise the possibility that p16 overexpression in the peritumoral stroma is associated with aggressive oncogenic behavior of endometrial SC.

Expression of cell cycle regulators and frequency of TP53 mutations in high risk gastrointestinal stromal tumors prior to adjuvant imatinib treatment

Despite of multitude investigations no reliable prognostic immunohistochemical biomarkers in GIST have been established so far with added value to predict the recurrence risk of high risk GIST besides mitotic count, primary location and size. In this study, we analyzed the prognostic relevance of eight cell cycle and apoptosis modulators and of TP53 mutations for prognosis in GIST with high risk of recurrence prior to adjuvant treatment with imatinib. In total, 400 patients with high risk for GIST recurrence were randomly assigned for adjuvant imatinib either for one or for three years following laparotomy. 320 primary tumor samples with available tumor tissue were immunohistochemically analyzed prior to treatment for the expression of cell cycle regulators and apoptosis modulators cyclin D1, p21, p16, CDK4, E2F1, MDM2, p53 and p-RB1. TP53 mutational analysis was possible in 245 cases. A high expression of CDK4 was observed in 32.8% of all cases and was associated with a favorable recurrence free survival (RFS), whereas high expression of MDM2 (12.2%) or p53 (35.3%) was associated with a shorter RFS. These results were independent from the primary KIT or PDGFRA mutation. In GISTs with higher mitotic counts was a significantly increased expression of cyclin D1, p53 and E2F1. The expression of p16 and E2F1 significantly correlated to a non-gastric localization. Furthermore, we observed a significant higher expression of p21 and E2F1 in KIT mutant GISTs compared to PDGFRA mutant and wt GISTs. The overall frequency of TP53 mutations was low (n = 8; 3.5%) and could not be predicted by the immunohistochemical expression of p53. In summary, mutation analysis in TP53 plays a minor role in the subgroup of high-risk GIST before adjuvant treatment with imatinib. Strong expression of MDM2 and p53 correlated with a shorter recurrence free survival, whereas a strong expression of CDK4 correlated to a better recurrence free survival.

[Gastrointestinal stromal tumors: surgical treatment and targeted therapy]

AIM

To improve surgical and complex treatment of patients with gastrointestinal stromal tumors (GIST).

MATERIAL AND METHODS

Our analysis included 97 GIST patients who were at Petrovsky Russian Research Center of Surgery and Moscow City Oncological Hospital #62 from January 2006 to September 2016.

RESULTS

Advisability of surgery for GIST patients was confirmed. We have assessed surgical outcomes, defined the indications for adjuvant targeted therapy depending on GIST prognostic risk and additional factors for unfavorable course of disease.

CONCLUSION

It was concluded that surgical treatment is preferred for patients with resectable GISTs. Adjuvant therapy is indicated in patients with high risk of progression if mutations indicating tumor sensitivity to the drugs are revealed. Adjuvant targeted therapy is not indicated in patients with low and very low risk of progression.

Clinicopathological and molecular characteristics of synchronous gastric adenocarcinoma and gastrointestinal stromal tumors

Synchronous gastric tumors that consist of both gastrointestinal stromal tumor (GIST) and adenocarcinoma are rare. We studied the clinicopathological and molecular characteristics of six cases containing both gastric adenocarcinoma and GIST. By means of immunohistochemical analysis, all GIST cells expressed CD117, CD34 and Dog1 in all six synchronous gastric adenocarcinomas with GIST, and in GIST alone. Sequencing analysis demonstrated that exon 11 c-kit mutations were present in two of six synchronous tumors and four of five GISTs. One of the two exon 11 c-kit mutations in synchronous adenocarcinomas with GISTs was an uncommon mutation of CTT > CCA at amino acid 576, and the other was a GTT deletion at amino acid 560. The mutation was a homozygous A > G mutation in exon 12 (amino acid 567) of PDGFR-α. We concluded that the exon 11 mutations were the most important in both cases of synchronous gastric adenocarcinoma with GIST and GIST alone. The mutation rate was higher in GIST alone than in synchronous adenocarcinoma with GIST.

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.