Association of HDM2 transcript levels with age of onset and prognosis in soft tissue sarcomas

Survival analysis and treatment strategies for limb liposarcoma patients with metastasis at presentation

Limited data exist on patients with limb liposarcoma (LLS) with metastasis at presentation Moreover, the potential prognostic factors of this patient population are poorly documented because of its rarity. Therefore, we conducted this study to evaluate the clinicopathologic characteristics and prognostic factors for patients with metastatic LLS.All patients with LLS with metastasis at presentation from 1975 to 2016 were identified by using the Surveillance, Epidemiology, and End Results (SEER) database. The following clinical data were derived from this clinical database: age, sex, histologic grade, subtype, size of tumor, surgery, radiotherapy, chemotherapy, vital status, cause of death, and survival duration. The Kaplan-Meier method was performed to calculate median survival time and draw survivorship curves. Cox-proportional hazards regression model was used to reveal the statistical independence between various variables.The present study collected 184 cases from SEER database for survival analysis. Mean age was 57.8 years with 63.6% (n = 117) men. The 3-year overall survival (OS) and cancer-specific survival (CSS) rates of this population were 27.8% and 30.1%, respectively. Univariate analysis revealed that age, tumor grade, and surgery were significantly correlated with survival. Sex and tumor size did not reach significant predictor status of survival. Multivariate analysis revealed that age at diagnosis <60, low tumor grade, and local surgery were significantly correlated with improved OS and CSS.Patients with LLS with metastasis at diagnosis experienced quite poor prognosis. Currently, surgery for the primary tumor significantly prolonged the survival of those patients, whereas chemotherapy and radiotherapy need to be further confirmed.

Influence of age and subtype in outcome of operable liposarcoma

AIM

Liposarcoma (LPS) is rare tumor deriving from adipocytes. LPS is classified into histological subtypes: well-differentiated (WDLPS), dedifferentiated (DDLPS), myxoid (MLPS) and pleomorphic (PLPS). A tailored approach taking into account the specificity of disease subtype and age at presentation could be helpful in delineating therapeutic management of liposarcoma. In this paper, we report a retrospective series of a single-institution cohort of patients with LPS, undergoing surgery and radiotherapy and/or chemotherapy. The aim of this study is to evaluate whether clinical characteristics, tumor- and treatment-related features affect clinical outcome in patients treated with curative intent for non-metastatic liposarcoma.

METHODS

Data of patients with locally advanced, non-metastatic liposarcoma treated between 1990 and 2015 were retrospectively reviewed. Data about patient, tumor and treatment features were collected. Two patients subgroups were identified according to age (cutoff: age < 65 years or > 65 years). Statistical analysis was performed to assess correlation between the above-cited variables and local recurrence-free survival (DFS-LR), distant metastasis-free survival, overall survival (OS) and disease-specific survival (DSS); moreover, differences in clinical outcome between the two age groups were identified.

RESULTS

Data of 186 patients were collected. At diagnosis, 27.4% of patients were 65 years or older. At a median follow-up of 8.6 years (range 0.1-27.3 years), Kaplan-Meier (KM) survival analysis showed that LR, DM, OS and DSS were 75.5%, 76.6%, 48.1% and 72.1%, respectively. KM analysis showed that age > 65, DDLPS and lower limb localization were related to LR (p = 0.001, p = 0.0001 and p = 0.0001, respectively). Association between LR, age and DDLPS persisted both at univariate (p = 0.003 and p = 0.0001, respectively) and multivariate Cox regression (CR) analysis (p = 0.024 and p = 0.002). Age, tumor depth and grading influenced distant recurrence, both at KM (p = 0.023, p = 0.026 and p = 0.016) and univariate CR (p = 0.026, p = 0.042 and p = 0.012). Age and grading were confirmed at multivariate analysis (p = 0.009 and p = 0.017). Patients with WDLPS and wide excision had significantly better OS (p = 0.001 and p = 0.03, respectively), while histological G3 and age > 65 were related with worse OS (p = 0.008 and p = 0.0001, respectively). Age, DDLPS and grade were related to OS at univariate (p = 0.0001, p = 0.0001 and p = 0.03, respectively) and multivariate CR analysis (p = 0.031, p = 0.0001 and p = 0.001, respectively). However, analyzing the specific causes of death, female died less often for tumor-related causes, with a DSS of 91.0% compared to 57.4% of male counterpart (p = 0.005). At Kaplan-Meier analysis, postoperative radiotherapy resulted in a statistically significant better disease-specific survival than postoperative radiotherapy (82.9% vs. 46.2%, p = 0.045). High grade correlated with poorer disease-specific survival (59.3%) than intermediate and low grade (73.4% and 91.6%, respectively) (p = 0.008). Association between DSS, sex and grade persisted both at univariate (p = 0.008 and p = 0.022, respectively) and multivariate Cox regression (CR) analysis (p = 0.014 and p = 0.038). Histotype-driven schedules of treatment should be developed to take into account biological heterogeneity of this disease. Further studies are needed to stratify patients subgroup and develop tailored treatment strategies (i.e., altered fractionations and different chemotherapy regimens in aggressive subtypes), in particular more prospective trials are needed to develop treatment guidelines in elderly STS, taking into account the frailty and the peculiarity of this subgroup.

MDM2 gene polymorphisms and risk of classic Kaposi's sarcoma among Iranian patients

A single-nucleotide polymorphism (SNP) in the promoter region of MDM2 (SNP309T>G, rs2279744) has been shown to increase the expression of the MDM2 protein in various cancer types. However, only one study has analyzed the role of the MDM2 polymorphism in the development of Kaposi's sarcoma (KS). The association of MDM2 SNP309 with classic KS risk was evaluated in 79 Iranian patients with classic KS and 123 healthy controls. The MDM2 SNP309 was genotyped using PCR and restriction fragment length polymorphism methods. No significant correlation was found between the SNP309 polymorphism in MDM2 promoter and classic KS risk. There was no significant correlation between gender and disease stage. However, a significant association was found between SNP309 GG genotype and younger age (≤50 years) (odds ratio 9.5, 95% confidence intervals 1.5-60, p = 0.03). Our findings support no major role for the MDM2 SNP309 in KS development although it might influence the clinical outcome of KS in younger patients.

p53-independent effects of Mdm2

Mdm2 is best known as the primary negative regulator of p53, but a growing body of evidence suggests that Mdm2 also has a number of functions independent of its role in regulating p53. Although these functions are not yet well-characterized, they have been implicated in regulating of a number of cellular processes, including cell-cycle control, apoptosis, differentiation, genome stability, and transcription, among others. It appears that Mdm2 exerts these functions through a surprisingly wide variety of mechanisms. For example, it has been shown that Mdm2 can ubiquitinate alternative targets, can stimulate the activity of transcription factors, and can directly bind to mRNA to regulate its stability. Dysregulation of p53-independent functions could be responsible for the oncogenic properties of Mdm2 seen even in the absence of p53, and may explain why approximately 10 % of human tumors overexpress Mdm2 instead of inactivating p53 through other mechanisms. As the p53-independent functions of Mdm2 present novel targets for potential therapeutic interventions, fully characterizing these cellular and pathogenic roles of Mdm2 will be important in the study of tumor biology and the treatment of cancer.

Splicing up mdm2 for cancer proteome diversity

Cancer cells often have high expression of Mdm2. However, in many cancers mdm2 is alternatively spliced, with more than 40 mRNA variants identified. Many of the alternative spliced mdm2 mRNAs have the potential to encode truncated Mdm2 isoforms. These putative Mdm2 isoforms can theoretically increase the diversity of the cancer proteome. The 3 best characterized are Mdm2-A, Mdm2-B, and Mdm2-C. As described in this review, the exogenous expression of these isoforms results in paradoxical phenotypes of transformation-associated growth as well as the inhibition of growth. Interestingly, these Mdm2 isoforms contribute tumor-promoting capacity in p53-null backgrounds. Herein we describe how alternative splicing of mdm2 may result in Mdm2 protein products that alter signal transduction to promote tumorigenesis. The tumor promoting capacity of Mdm2 isoforms is discussed in the context of functions that do not require the inhibition of p53. When N-terminal portions of Mdm2 are missing, the biochemical functions encoded by exon 12 are proposed to become more important. This may result in growth promoting functions when wild-type p53 is absent or compromised. The p53-independent tumor promoting activity of Mdm2 is proposed to result from C-terminal biochemical contributions of DNA binding, RNA binding, nucleolar localization, and nucleotide binding.

A novel splice variant of the stem cell marker LGR5/GPR49 is correlated with the risk of tumor-related death in soft-tissue sarcoma patients

BACKGROUND

The human leucine-rich, repeat-containing G protein-coupled receptor (LGR) 5, also called GPR49, is a marker of stem cells in adult intestinal epithelium, stomach and hair follicles. LGR5/GPR49 is overexpressed in tumors of the colon, ovary and liver and in basal cell carcinomas. Moreover, an expression in skeletal muscle tissues was also detected. However, there has been no investigation regarding the expression and function of LGR5/GPR49 in soft-tissue sarcomas (STS) yet.

METHODS

Seventy-seven frozen tumor samples from adult STS patients were studied using quantitative real-time TaqMan™ PCR analysis. The mRNA levels of wild type LGR5/GPR49 and a newly identified splice variant of LGR5/GPR49 lacking exon 5 (that we called GPR49Δ5) were quantified.

RESULTS

A low mRNA expression level of GPR49Δ5, but not wild type LGR5/GPR49, was significantly correlated with a poor prognosis for the disease-associated survival of STS patients (RR = 2.6; P = 0.026; multivariate Cox's regression hazard analysis). Furthermore, a low mRNA expression level of GPR49Δ5 was associated with a shorter recurrence-free survival (P = 0.043). However, tumor onset in patients with a lower expression level of GPR49Δ5 mRNA occurred 7.5 years later (P = 0.04) than in patients with a higher tumor level of GPR49Δ5 mRNA.

CONCLUSION

An attenuated mRNA level of the newly identified transcript variant GPR49Δ5 is a negative prognostic marker for disease-associated and recurrence-free survival in STS patients. Additionally, a lower GPR49Δ5 mRNA level is associated with a later age of tumor onset. A putative role of GPR49Δ5 expression in tumorigenesis and tumor progression of soft tissue sarcomas is suggested.

Elevated transcript levels from the MDM2 P1 promoter and low p53 transcript levels are associated with poor prognosis in human pancreatic ductal adenocarcinoma

OBJECTDIVES: Mouse double minute 2 is a key negative regulator of the p53 protein, a central node in the mediation of tumor suppression. The MDM2 gene contains 2 differently regulated promoters, MDM2-P1 and MDM2-P2, which differ strongly in their biological and clinical importance.

METHODS

We assess the clinical significance of the expression of messenger RNA (mRNA) transcripts originating from both MDM2 promoters, measured with quantitative reverse transcription polymerase chain reaction in microdissected tissues from 57 patients with pancreatic ductal adenocarcinoma (PDAC). Furthermore, we determine the clinical relevance of p53 mRNA transcript expression and incorporate the somatic p53 mutational status into our analyses.

RESULTS

Interestingly, elevated transcript levels from the P1 promoter, but not the P2 promoter, associate significantly with up to 6.3-fold increased relative risk for tumor-related death (Cox multivariate analysis: P = 0.013). Furthermore, transcripts originating from both MDM2 promoters are found to correlate significantly with p53 mRNA levels (up to r = 0.315; P = 0.017). In addition, low p53 mRNA expression associates with worse PDAC prognosis (relative risk = 2.28; P = 0.021).

CONCLUSIONS

This study presents the first differentiated analysis of the MDM2-P1, MDM2-P2, and p53 transcript expression in human PDAC and demonstrates the significant clinical implications of those transcripts. Furthermore, it suggests an additional facet in the regulation of MDM2 via its P1 promoter in this malignancy.