Immunohistochemical analysis of p53 and p21WAF1/Cip1 expression in primary intracranial germ cell tumors

CNS Germ Cell Tumors: Molecular Advances, Significance in Risk Stratification and Future Directions

Central Nervous System Germ Cell Tumors (CNS GCTs) represent a subtype of intracranial malignant tumors characterized by highly heterogeneous histology. Current diagnostic methods in clinical practice have notable limitations, and treatment strategies struggle to achieve personalized therapy based on patient risk stratification. Advances in molecular genetics, biology, epigenetics, and understanding of the tumor microenvironment suggest the diagnostic potential of associated molecular alterations, aiding risk subgroup identification at diagnosis. Furthermore, they suggest the existence of novel therapeutic approaches targeting chromosomal alterations, mutated genes and altered signaling pathways, methylation changes, microRNAs, and immune checkpoints. Moving forward, further research is imperative to explore the pathogenesis of CNS GCTs and unravel the intricate interactions among various molecular alterations. Additionally, these findings require validation in clinical cohorts to assess their role in the diagnosis, risk stratification, and treatment of patients.

​Occult extracranial malignancy after complete remission of pineal mixed germ cell tumors: a rare case report and literature review

BACKGROUND

​Extracranial metastasis can occur in intracranial germ cell tumors (GCTs), but it is very rare. Recurrence or metastasis of non-germinomatous germ cell tumors (NGGCTs) is often accompanied by elevated tumor markers. ​Occult extracranial metastases or recurrences with negative markers are often difficult to detect in time, resulting in a very poor prognosis.

CASE PRESENTATION

A 12-year-old boy was admitted to our institution with dizziness, headache, vomiting, and sleepiness. Magnetic resonance imaging (MRI) showed a pineal mass, accompanied by a significant increase in serum alpha-fetoprotein (AFP). The patient subsequently underwent total removal of the tumor. Pathology revealed that the tumor was a mixed GCT, consisting of mature teratoma, germinoma, and yolk sac tumor. Intracranial GCT achieved complete remission after intensive adjuvant chemotherapy and radiotherapy. Regular follow-up MRI revealed no recurrence of the intracranial tumor and continued monitoring of tumor markers revealed no abnormalities. ​Eight months later, the patient was readmitted due to progressive abdominal pain. Imaging and physical examination revealed abdominal occupation and lymphatic mass in the neck. He received salvage chemotherapy, anti-PD-1 immunotherapy, and palliative chemotherapy, but still developed multiple organ dysfunction syndromes (MODS) due to tumor progression and eventually died after one month.

CONCLUSIONS

​This profound case suggests that intracranial NGGCTs may develop occult extracranial malignancy, which can be very severe at the time of clinical symptoms and has an extremely poor prognosis. Therefore, in addition to tumor marker monitoring, regular follow-up with extracranial imaging may be warranted to detect extracranial tumors as early as possible, although perhaps not as frequently as with neuroimaging.

Recent advances in molecular biology and treatment strategies for intracranial germ cell tumors

BACKGROUND

Intracranial germ cell tumors (IGCTs) are a group of rare pediatric brain tumors which include various subtypes. The current understanding of the etiology of the tumors and their optimal management strategies remain controversial.

DATA SOURCES

The data on IGCTs were collected from articles published in the past 20 years, and the origin and etiology of IGCTs at molecular level as well as the relative roles of varied treatment strategies in different prognosis groups according to Matsutani's classification were reviewed.

RESULTS

Recent cellular and molecular evidence suggests that IGCTs may arise from the transformation of endogenous brain cells; and findings in the molecular characterization of IGCTs suggest roles of CCND2, RB1, and PRDM14 in the pathogenesis of IGCTs and identify the KIT/RAS and AKT1/mTOR pathways as potential therapeutic targets in future. According to Matsutani's classification of IGCTs, the good prognosis group includes both germinomas and mature teratomas. For germinomas, both radiation alone and reduced-dose radiotherapy in combination with adjuvant chemotherapy are effective, while complete surgical excision is recommended for mature teratomas. In the intermediate prognosis group, immature teratoma has been successfully treated with gamma knife surgery. However, for intermediate prognosis IGCTs other than immature teratomas, gross total resection with adjuvant chemotherapy and radiotherapy or gamma knife surgery may be necessary to achieve cure. In the poor prognosis group, survival outcomes are unsatisfactory, and complete surgical resection combined with more intensive chemotherapy and radiotherapy remains the best available treatment option at this time.

CONCLUSIONS

IGCTs should be strictly classified according to their pathological categories before administering pathology-specific treatments. Although open microsurgical excision is the traditional surgical strategy for IGCTs, recent publications also support the role of endoscopic surgical options for pineal region IGCTs.

Brg1 Enables Rapid Growth of the Early Embryo by Suppressing Genes That Regulate Apoptosis and Cell Growth Arrest

SWI/SNF (switching/sucrose nonfermenting)-dependent chromatin remodeling establishes coordinated gene expression programs during development, yet important functional details remain to be elucidated. We show that the Brg1 (Brahma-related gene 1; Smarca4) ATPase is globally expressed at high levels during postimplantation development and its conditional ablation, beginning at gastrulation, results in increased apoptosis, growth retardation, and, ultimately, embryonic death. Global gene expression analysis revealed that genes upregulated in Rosa26CreERT2; Brg1(flox/flox) embryos (here referred to as Brg1(d/d) embryos to describe embryos with deletion of the Brg1(flox/flox) alleles) negatively regulate cell cycle progression and cell growth. In addition, the p53 (Trp53) protein, which is virtually undetectable in early wild-type embryos, accumulated in the Brg1(d/d) embryos and activated the p53-dependent pathways. Using P19 cells, we show that Brg1 and CHD4 (chromodomain helicase DNA binding protein 4) coordinate to control target gene expression. Both proteins physically interact and show a substantial overlap of binding sites at chromatin-accessible regions adjacent to genes differentially expressed in the Brg1(d/d) embryos. Specifically, Brg1 deficiency results in reduced levels of the repressive histone H3 lysine K27 trimethylation (H3K27me3) histone mark and an increase in the amount of open chromatin at the regulatory region of the p53 and p21 (Cdkn1a) genes. These results provide insights into the mechanisms by which Brg1 functions, which is in part via the p53 program, to constrain gene expression and facilitate rapid embryonic growth.

Unravelling mechanisms of cisplatin sensitivity and resistance in testicular cancer

Testicular cancer is the most frequent solid malignant tumour type in men 20-40 years of age. At the time of diagnosis up to 50% of the patients suffer from metastatic disease. In contrast to most other metastatic solid tumours, the majority of metastatic testicular cancer patients can be cured with highly effective cisplatin-based chemotherapy. This review aims to summarise the current knowledge on response to chemotherapy and the biological basis of cisplatin-induced apoptosis in testicular cancer. The frequent presence of wild-type TP53 and the low levels of p53 in complex with the p53 negative feed-back regulator MDM2 contribute to cisplatin sensitivity. Moreover, the high levels of the pluripotency regulator Oct4 and as a consequence of Oct4 expression high levels of miR-17/106b seed family and pro-apoptotic Noxa and the low levels of cytoplasmic p21 (WAF1/Cip1) appear to be causative for the exquisite sensitivity to cisplatin-based therapy of testicular cancer. However, resistance of testicular cancer to cisplatin-based therapy does occur and can be mediated through aberrant levels of the above mentioned key players. Drugs targeting these key players showed, at least pre-clinically, a sensitising effect to cisplatin treatment. Further clinical development of such treatment strategies will lead to new treatment options for platinum-resistant testicular cancers.

Diagnostic utility and correlation of tumor markers in the serum and cerebrospinal fluid of children with intracranial germ cell tumors

PURPOSE

In order to predict whether tumor markers assist in the histopathologic diagnosis of germ cell tumors (GCTs), we analyzed the correlation of beta human chorionic gonadotropin (βhCG) and alpha-fetoprotein (AFP) in serum and cerebrospinal fluid (CSF) samples at baseline and subsequent follow-up examinations.

METHOD

A retrospective study of patients diagnosed with intracranial GCTs between July 1985 and February 2011 at our institution was conducted to review clinical, surgical, radiological, laboratory, and histopathologic data.

RESULTS

Of the 67 patients eligible for the study, 42 had germinomas and 25 non-germinomatous GCTs. At baseline, serum and CSF AFP agreed in 97.9 % of patients (Cohen's Kappa 0.93). Baseline βhCG samples agreed in only 72.5 % of patients (Cohen's Kappa 0.46). In most cases, values were higher in serum for AFP and in CSF for βhCG. ROC curves estimated from logistic regression model indicated that CSF and serum samples had almost equal diagnostic utility, and the DeLong test showed that the difference in area under curves was not statistically significant. During follow-up (185 paired CSF and serum values from 43 patients), 90.3 % of AFP values correlated between CSF and serum (Cohen's Kappa 0.22, showing fair agreement). For βhCG, 96.2 % of values agreed in serum and CSF (Cohen's Kappa 0.61).

CONCLUSIONS

In some patients, intracranial GCTs can be diagnosed based solely upon positive serum AFP values. In addition, marker values from serum only may be sufficient to predict tumor relapse at interval follow-up examinations.

Management of primary intracranial germ cell tumors

Primary intracranial germ cell tumors are rare and usually localized in the pineal and the suprasellar regions. They are divided into the following histologic types: germinoma, teratoma (mature, immature, malignant), choriocarcinoma, embryonal carcinoma, endodermal sinus tumor (yolk sac tumor), and mixed tumors. Clinically, they are manifested with ocular signs or signs of obstructive hydrocephalus. Localized germinomas are treated with radiation therapy and exhibit a relatively good prognosis. Chemotherapy is reserved for disseminated germinomas. Mature teratomas are treated with surgery. The rest of germ cell tumors are managed with various combinations of surgery, chemotherapy, and radiotherapy depending on the tumor type. If the tumors secrete beta-human chorionic gonadotrophin (hCG) or alpha-fetoprotein (FP), these tumor markers can be used to accurately monitor response to treatment. Prognosis is best for germinomas and mature teratomas and worst for choriocarcinomas and embryonal carcinomas.