MDM2 mRNA expression in the p53 pathway may predict the potential of invasion and liver metastasis in colorectal cancer

Exploring the Key Signaling Pathways and ncRNAs in Colorectal Cancer

Colorectal cancer (CRC) is the third most prevalent cancer to be diagnosed, and it has a substantial mortality rate. Despite numerous studies being conducted on CRC, it remains a significant health concern. The disease-free survival rates notably decrease as CRC progresses, emphasizing the urgency for effective diagnostic and therapeutic approaches. CRC development is caused by environmental factors, which mostly lead to the disruption of signaling pathways. Among these pathways, the Wingless/Integrated (Wnt) signaling pathway, Phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway, Mitogen-Activated Protein Kinase (MAPK) signaling pathway, Transforming Growth Factor-β (TGF-β) signaling pathway, and p53 signaling pathway are considered to be important. These signaling pathways are also regulated by non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). They have emerged as crucial regulators of gene expression in CRC by changing their expression levels. The altered expression patterns of these ncRNAs have been implicated in CRC progression and development, suggesting their potential as diagnostic and therapeutic targets. This review provides an overview of the five key signaling pathways and regulation of ncRNAs involved in CRC pathogenesis that are studied to identify promising avenues for diagnosis and treatment strategies.

UBE2J1 knockdown promotes cell apoptosis in endometrial cancer via regulating PI3K/AKT and MDM2/p53 signaling

Emerging evidence has demonstrated that ubiquitin conjugating enzyme E2 J1 (UBE2J1) exerts pivotal function in many cancers. UBE2J1 was reported to be dysregulated in endometrial cancer (EC). This study was designed to further investigate the regulatory character and mechanism of UBE2J1 in EC. Bioinformatic tools and databases were used to analyze gene expression pattern and gene expression correlation in EC tissues, and the prognosis of EC patients. Gene expression was evaluated by reverse-transcription quantitative polymerase chain reaction. Western blot was used for protein level detection. In vitro cell apoptosis was detected by flow cytometry analyses and TUNEL assays. In vivo cell apoptosis was evaluated by detecting Bax and Bcl-2 expression in tumor tissues via immunohistochemical and western blot analyses. In this study, UBE2J1 knockdown promoted cell apoptosis in EC cells and in mouse models of EC. PI3K and AKT expression is positively correlated with UBE2J1 level and is related to poor prognosis of EC patients. UBE2J1 knockdown repressed the PI3K/AKT pathway both in vitro and in vivo. UBE2J1 downregulation decreased MDM2 expression, but increased p53 expression. MDM2 overexpression reverses the promotion of UBE2J1 knockdown on cell apoptosis in EC. Overall, UBE2J1 knockdown induces cell apoptosis in EC by inactivating the PI3K/AKT signaling and suppressing the MDM2/p53 signaling.

Combined use of murine double minute-2 promoter methylation and serum AFP improves diagnostic efficiency in hepatitis B virus-related hepatocellular carcinoma

Objective: Hepatocellular carcinoma (HCC) accounts for approximately 85% of all cases of liver cancer. In China, chronic hepatitis B virus-related HCC (HBV-related HCC) is the most common type of HCC. However, the majority of HBV-related HCC patients are asymptomatic, and the best opportunities for treating these patients are missed. The precise diagnosis of HBV-related HCC is crucial. The main purpose of this study was to evaluate the diagnostic value of murine double minute-2 (MDM2) promoter methylation in HBV-related HCC patients. Methods: The methylation status of the MDM2 promoter was detected by methylation-specific PCR. The MDM2 expression levels were validated by quantitative real-time PCR. Enzyme-linked immunosorbent assay was used to determine the levels of interleukin-6 (IL-6) and tumor-necrosis factor-α (TNF-α) in plasma. Results: The methylation frequency of the MDM2 promoter was decreased in HBV-related HCC patients. The MDM2 mRNA levels of patients with HBV-related HCC were higher than those of patients with liver cirrhosis and chronic hepatitis B. The plasma levels of IL-6 and TNF-α were significantly higher in HBV-related HCC patients than that in liver cirrhosis and chronic hepatitis B patients. The TNF-α levels were higher in the unmethylated MDM2 promoter group than in the methylated MDM2 promoter group in HBV-related HCC patients. Moreover, the combination of MDM2 promoter methylation and alpha-fetoprotein (AFP) improved the diagnosis of HBV-related HCC. Conclusions: Our study indicates, for the first time, that MDM2 promoter hypomethylation is present in HBV-related HCC patients. The combination of MDM2 promoter methylation and AFP can greatly improve diagnostic efficiency in HBV-related HCC, which might provide a new method for HBV-related HCC diagnosis.

Genetic polymorphisms of TP53 (rs1042522) and MDM2 (rs2279744) and colorectal cancer risk: An updated meta-analysis based on 59 case-control studies

OBJECTIVE

Several earlier reports implicated TP53 (rs1042522) and MDM2 (rs2279744) variants in outcome of colorectal cancer (CRC), but with inconclusive findings. This current meta-analysis designed to uncover the role of these variants in CRC risk.

METHODOLOGY

Two independent investigators extracted 59 eligible case-control studies from different electronic databases involving Scopus, Web of Science and PubMed prior to June 2019. Pooled odds ratios (ORs) and "95% confidence intervals (CIs)" were computed for different hereditary models. Stratification and heterogeneity analyses, and "Begg's funnel plots" were conducted. In silico data analyses of the functional and structural properties of the study variants were applied.

RESULTS

In general, 47 and 16 case-control reports for TP53 (11,589 patients and 13,622 controls) and MDM2 (6841 CRC patients and 8792 healthy controls), respectively were enrolled in this meta-analysis. A significant association of TP53 (rs1042522) variant with increased CRC risk in overall pooled subjects under recessive model [(CC vs. GC + GG, OR = 1.134, 95% CI = 1.006-1.278, P = 0.039)] was observed. Moreover, an evidence of MDM2 (rs2279744) association with increased CRC risk in overall pooled subjects under dominant and heterozygote models [(TG + GG vs. TT, OR = 1.120, 95% CI = 1.003-1.250, P = 0.044) and (TG vs. TT, OR = 1.189, 95% CI = 1.076-1.313, P = 0.001), respectively] was reported. Additionally, TP53 (rs1042522) and MDM2 (rs2279744) showed an association with CRC risk among Asians and Africans under a recessive model, and among Asians under different genetic models, respectively, by stratification analysis.

CONCLUSION

TP53 (rs1042522) and MDM2 (rs2279744) variants might represent candidate risk factors for CRC susceptibility.

Emerging paradigms in the treatment of liver metastases in colorectal cancer

Efforts to combat colorectal cancer have benefited from improved screening and surveillance, which facilitates early detection. The survival rate associated with diagnosis at stage I is approximately 90%. However, progress in improving survival in metastatic colorectal cancer (mCRC) has been minimal. This review focuses on mCRC with special emphasis on the molecular aspects of liver metastases, which is one of the most frequently involved organ site. Better molecular evidence is required to guide the decisions for surgical and other interventions used in the clinical management of mCRC. Results from different treatment modalities have exposed significant gaps in the existing paradigms of the mCRC management. Indeed there is a critical need to better understand molecular events and pathways that lead to colorectal cancer liver metastasis. Such a focused approach may help identify biomarkers and drug targets that can be useful in the clinical applications. With this focus, we provide an account of the molecular pathways involved in the spread of CRC to the liver. Specifically, the molecular changes at the DNA and RNA levels that are associated with liver metastases are discussed. Similarly, we describe relevant microRNAs that are identified as regulators of gene expression and can also serve as biomarkers. Conventionally applied biomarkers are not yet specific and sensitive enough to be relied in routine clinical decision making. Hence search for novel biomarkers is critically needed especially if these can be utilized using liquid biopsies. This review provides a comprehensive analysis of current molecular evidence along with potential future directions that could reshape the diagnostic and management paradigms and thus mitigate the devastating impact of colorectal cancer metastasis to the liver.

Opposite regulation of MDM2 and MDMX expression in acquisition of mesenchymal phenotype in benign and cancer cells

Plasticity of cancer cells, manifested by transitions between epithelial and mesenchymal phenotypes, represents a challenging issue in the treatment of neoplasias. Both epithelial-mesenchymal transition (EMT) and mesenchymal-epithelial transition (MET) are implicated in the processes of metastasis formation and acquisition of stem cell-like properties. Mouse double minute (MDM) 2 and MDMX are important players in cancer progression, as they act as regulators of p53, but their function in EMT and metastasis may be contradictory. Here, we show that the EMT phenotype in multiple cellular models and in clinical prostate and breast cancer samples is associated with a decrease in MDM2 and increase in MDMX expression. Modulation of EMT-accompanying changes in MDM2 expression in benign and transformed prostate epithelial cells influences their migration capacity and sensitivity to docetaxel. Analysis of putative mechanisms of MDM2 expression control demonstrates that in the context of defective p53 function, MDM2 expression is regulated by EMT-inducing transcription factors Slug and Twist. These results provide an alternative context-specific role of MDM2 in EMT, cell migration, metastasis, and therapy resistance.

Copy number variation of E3 ubiquitin ligase genes in peripheral blood leukocyte and colorectal cancer

Given that E3 ubiquitin ligases (E3) regulate specific protein degradation in many cancer-related biological processes. E3 copy number variation (CNV) may affect the development and prognosis of colorectal cancer (CRC). Therefore, we detected CNVs of five E3 genes in 518 CRC patients and 518 age, gender and residence matched controls in China, and estimated the association between E3 gene CNVs and CRC risk and prognosis. We also estimated their interactions with environmental factors and CRC risk. We find a significant association between the CNVs of MDM2 and CRC risk (amp v.s. wt: odds ratio = 14.37, 95% confidence interval: 1.27, 163.74, P = 0.032), while SKP2 CNVs may significantly decrease CRC risk (del v.s. wt: odds ratio = 0.32, 95% confidence interval: 0.10, 1.00, P = 0.050). However, we find no significant association between the CNVs of other genes and CRC risk. The only significant gene-environment interaction effects are between SKP2 CNVs and consumption of fish and/or fruit (P = 0.014 and P = 0.035) and between FBXW7 CNVs and pork intake (P = 0.040). Finally, we find marginally significant association between β-TRCP CNVs and CRC prognosis (amp v.s. wt, hazard ratio = 0.42, 95% confidence interval: 0.19, 0.97, P = 0.050).

Relationships between p14ARF Gene Methylation and Clinicopathological Features of Colorectal Cancer: A Meta-Analysis

We conducted a meta-analysis to explore the relationships between p14^ARF gene methylation and clinicopathological features of colorectal cancer (CRC). Databases, including Pubmed, Embase and Cochrane Library, were searched and, finally, a total of 18 eligible researches encompassing 1988 CRC patients were selected. Combined odds ratios (ORs) with 95% confidence intervals (95% CIs) were evaluated under a fixed effects model for absence of heterogeneity. Significant associations were observed between p14^ARF gene methylation and tumor location (OR = 2.35, 95% CI: 1.55–3.55, P = 0.001), microsatellite instability (MSI) status (OR = 3.28, 95% CI: 2.12–5.07, P<0.0001). However, there were no significant associations between p14^ARF gene methylation and tumor stage, tumor differentiation. We concluded that p14^ARF gene methylation may be significantly associated with tumor location, and MSI status of CRC.

Overexpression of microRNA‑125a‑3p effectively inhibits the cell growth and invasion of lung cancer cells by regulating the mouse double minute 2 homolog/p53 signaling pathway

MicroRNAs (miRs) are a family of small non-coding RNAs that are 21‑24 nucleotides in length. Decreased expression of hsa‑miR‑125a‑3p is observed in a number of patients with non‑small cell lung cancer; however, it is not clear how this miRNA regulates the growth and invasion of lung tumor cells. The aim of the present study was to identify the function of hsa‑miR‑125a‑3p in the growth and invasion of lung cancer cells. The expression of hsa‑miR‑125a‑3p in the A549, NCI‑H460 and SPCA‑1 lung cancer cell lines was analyzed by reverse transcription‑quantitative polymerase chain reaction and the human bronchiolar epithelium cell line (HBE) was used as a control. The results demonstrated that the expression of hsa‑miR‑125a‑3p was significantly lower in NCI‑H460, A549 and SPCA‑1 cells, compared with that in HBE cells. Overexpression of sense miR‑125a‑3p in the A549 lung cancer cell line inhibited cell proliferation for 5‑7 days (P<0.01), and transfection of antisense miR‑125a‑3p did not suppress the cell growth of the lung cancer cells. In addition, overexpression of miR‑125a‑3p in the NCI‑H460 lung cancer cell line markedly induced cell apoptosis, which was detected by fluorescence‑activated cell sorting with annexin V‑fluorescein isothiocyanate/propidium iodide staining. The results of the Transwell migration assay also revealed that transfection of miR‑125a‑3p resulted in decreased migration of lung cancer tumor cells. The pro‑apoptotic gene p53 expression was detected by western blot analysis. The results revealed that the expression of mouse double minute (MDM)‑2 homolog, the principal cellular antagonist of p53, was decreased and p53 expression was upregulated in sense has‑miR‑125a‑3p transfected A549 cells. This was consistent with that observed in NCI‑H460 cells, suggesting that hsa‑miR‑125a‑3p may be involved in the regulation of the MDM2/p53 signaling pathway in lung cancer cells. In conclusion, overexpression of hsa‑miR‑125a‑3p significantly inhibited the proliferation and invasion of lung cancer cells, which may aid in determining the mechanisms underlying the development of lung cancer.

p53, MDM2, eIF4E and EGFR expression in nasopharyngeal carcinoma and their correlation with clinicopathological characteristics and prognosis: A retrospective study

In the present study, the expression of p53, mouse double minute 2 homolog (MDM2), eukaryotic translation initiation factor 4E (eIF4E), and epidermal growth factor receptor (EGFR) were investigated in nasopharyngeal carcinoma (NPC), and the correlation between their expression and clinicopathological characteristics and prognosis was analyzed. The medical records of 96 NPC patients who had undergone biopsy prior to radical radiotherapy and chemotherapy between 2005 and 2009 were reviewed, retrospectively. All patients received intensity-modulated radiotherapy with concurrent platinum-based chemotherapy. Patients were followed-up for three years. Streptavidin-peroxidase immunohistochemistry was used to evaluate the expression of p53, MDM2, eIF4E and EGFR in NPC biopsy specimens, and the association between their expression and clinical parameters and survival was analyzed. The p53, MDM2, eIF4E and EGFR expression rates were 65.6% (63/96), 79.16% (76/96), 77.08% (74/96) and 89.5% (86/96), respectively. p53 (χ²,20.322; P=0.001) and EGFR (χ²,8.337; P=0.005) expression were found to correlate with T stage, whereas MDM2 (χ²,16.361; P=0.001) expression was found to correlate with lymph node metastasis. p53 expression was found to inversely correlate with MDM2 expression (r, −3.24; P<0.05). Three-year survival rates were lower in p53-positive (76.2%) patients when compared with p53-negative (93.9%) patients. In addition, three-year survival rates were lower in EGFR-positive (75.8%) patients than in EGFR-negative patients (91.2%). The Cox proportional-hazards regression model revealed that p53 (β,−0.455; χ²,5.491; P=0.019) and EGFR (β, 3.93; χ², 11.95; P=0.001) expression were independent prognostic factors. Thus, it was hypothesized that p53 and EGFR expression present potential unfavorable prognostic markers for patients with NPC.

Biological significance of promoter hypermethylation of p14/ARF gene: relationships to p53 mutational status in Tunisian population with colorectal carcinoma

One of the most important pathways which are frequently affected in colorectal cancer is p53/ (MDM2)/p14ARF pathway. We aim to determine the methylation pattern of p14/ARF in relation to mutation of p53. This correlation was studied to investigate whether their alterations could be considered as a predictor factor of prognosis in colorectal cancer and whether it can be useful in early-stage diagnosis. Statistical analyses show that p14/ARF hypermethylation was correlated with rectum location (p = 0.004), primary TNM stage (p = 0.016), and advanced Astler–Coller stage (p = 0.024). The RT-PCR that revel 31 % of patients did not express p14/ARF mRNA or at very low level. A high concordance between CpG hypermethylation and the low levels (p < 0.005) was shown. In addition, our analyses demonstrate that patients with mutation in the p53 gene have a lack of the protein expression (p < 0.005). This category with negative expression of p53 had a shorter survival rate (p < 0.005). On the one hand, MSP pattern of p14/ARF were correlated with a lack of p53 expression (p = 0.007). We found that p53/p14ARF pathway was frequently deregulated among our patients. In our study, we demonstrate that hypermethylation of p14/ARF occurs early during CRC tumorogenesis. However, we did not find correlation between p14/ARF and survival. These results suggest that p14/ARF methylation pattern may constitute a predictor factor of CRC in early stage but it could not be considered as a prognostic factor. On the other hand and because of the reversibility of the methylation mechanism, it may be appropriate to target the demethylation of p14/ARF to develop new drogues for CRC.

Current evidence on the relationship between SNP309 polymorphism in the MDM2 gene and colorectal cancer risk

It has been demonstrated that MDM2 is a well-established negative regulator of the p53 protein and might be associated with a significantly earlier age of onset of several tumors, including colorectal cancer (CRC). In recent years, a T to G substitution (SNP309) in the promoter of MDM2 has been extensively studied as a potential CRC risk factor; however, the results are inconsistent. To derive a more precise estimation of association between MDM2 SNP309 polymorphism and CRC risk, we conducted a meta-analysis of 11 studies with 4,050 CRC cases and 3,688 controls. For MDM2 SNP309 polymorphism, no obvious associations were found for all genetic models when all studies were pooled into the meta-analysis. In the subgroup analyses by ethnicity, source of controls, and Hardy-Weinberg equilibrium (HWE) in controls, a significantly increased risk was observed among Asians (heterozygous model: odds ratio (OR) = 1.21, 95% confidence interval (CI) = 1.06-1.39, P = 0.005), population-based studies (heterozygous model: OR = 1.17, 95% CI = 1.02-1.34, P = 0.027), and among studies without the HWE (recessive model: OR = 1.42, 95% CI = 1.03-1.94, P = 0.030). When excluding three studies deviated from HWE, the significant results were also observed for heterozygous model in overall population (OR = 1.16, 95% CI = 1.02-1.31, P = 0.020). No publication bias was found in the present study. In conclusion, this meta-analysis suggests that MDM2 SNP309 polymorphism was associated with CRC susceptibility, especially among Asians. Further research is needed to assess possible gene-gene or gene-environment-lifestyle interactions on CRC.

Impact of MDM2 polymorphism: increased risk of developing colorectal cancer and a poor prognosis in the Tunisian population

INTRODUCTION

MDM2 was originally identified as an oncoprotein that binds to p53 and inhibits p53-mediated transactivation. Scientists have described functional single-nucleotide polymorphisms (SNP) in the MDM2 gene. They showed that the genotype of SNP 309 induces an increase in the level of MDM2 protein, which causes attenuation of the p53 pathway. In this study, we sought to investigate whether this polymorphism was related to risk of colorectal cancer and whether there were relationships between SNP 309 and protein expression or clinicopathological variables in Tunisian patients.

MATERIALS AND METHODS

To investigate the effect of this polymorphism in colorectal cancer pathogenesis, we genotyped 167 patients and 167 blood donors. Immunohistochemistry was performed on normal mucosa and tumor.

RESULTS

The rates of MDM2 genotypes were 6.6% for wild-type (T/T) and 93.4% for the SNP 309 polymorphic genotype (T/G and G/G) in patients and 38.3 and 61.7% in controls, respectively. There were significant differences in the frequencies of genotypes between patients and controls (P<0.01). We did not find any relationship between genotypes and clinicopathological features of patients, except in the case of the nonmucinous histological subtype (P=0.001). Moreover, we found that patients with the wild-type genotype (T/T) had significantly more favorable clinical outcome than did patients with the SNP 309 genotype (T/G, G/G) (P=0.005). In addition, we found an association between positive expression of p53 and polymorphic genotypes of MDM2 (T/G, G/G) (P=0.037). There was a significant association between tumoral immunostaning and MDM2 polymorphism (P=0.01).

CONCLUSION

Our results suggest that the MDM2 polymorphism is significantly associated with colorectal cancer risk and may provide useful prognostic information for Tunisian patients with colorectal cancer.

MHC class I molecules act as tumor suppressor genes regulating the cell cycle gene expression, invasion and intrinsic tumorigenicity of melanoma cells

The alteration of MHC class I (MHC-I) expression is a frequent event during cancer progression, allowing tumor cells to evade the immune system. We report that the loss of one major histocompatibility complex haplotype in human melanoma cells not only allowed them to evade immunosurveillance but also increased their intrinsic oncogenic potential. A second successive defect in MHC-I expression, MHC-I total downregulation, gave rise to melanoma cells that were more oncogenic per se in vivo and showed a higher proliferation rate and greater migratory and invasive potential in vitro. All these processes were reversed by restoring MHC-I expression via human leukocite antigen-A2 gene transfection. MHC-I cell surface expression was inversely correlated with intrinsic oncogenic potential. Modifications in the expression of various cell cycle genes were correlated with changes in MHC-I expression; the most important differences among the melanoma cell lines were in the transcriptional level of AP2-alpha, cyclin A1 and p21WAF1/CIP1. According to these results, altered MHC-I expression in malignant cells can directly increase their intrinsic oncogenic and invasive potential and modulate the expression of cell cycle genes. These findings suggest that human leukocite antigen class I molecules may act directly as tumor suppressor genes in melanoma.

Evaluation of suitable reference genes for normalization of real-time reverse transcription PCR analysis in colon cancer

Background

Real-time reverse transcription PCR (qRT-PCR) is frequently used for gene expression quantification due to its methodological reproducibility and sensitivity. The gene expression is quantified by normalization to one or more reference genes which are presumed stably expressed throughout a given experiment. The aim of this study was to validate a standardized experimental setup to identifying reference genes for normalization of qRT-PCR in the metastatic and non-metastatic colon cancer.

Methods

In this study, expression of 16 commonly used reference genes was quantified in tumour tissue and individual-matched normal mucosa in 18 non-metastatic colon cancer patients and 20 colon cancer patients with distant metastases using TaqMan Low Density Array (TLDA). The expression stability was determined and compared by means of geNorm and NormFinder.

Results

Two pairs of genes, HPRT1/PPIA and IPO8/PPIA, were identified to be suitable to normalize gene expression data in metastatic and non-metastatic colon cancer patients, according to geNorm and NormFinder respectively.

Conclusion

We propose a standardized approach of finding the most suitable reference gene(s) in every qRT-PCR experiment using TLDA.

MDM2 gene amplification in colorectal cancer is associated with disease progression at the primary site, but inversely correlated with distant metastasis

MDM2 is a crucial negative regulator of the TP53 tumor suppressor and almost 10% of human tumors exhibit MDM2 amplification. Although TP53 pathway perturbation has been extensively examined in colorectal cancer (CRC), only one previous report has evaluated MDM2 amplification in relation to clinicopathological factors. In that report, MDM2 amplification was shown to be associated with disease progression from Dukes' Stages A to D. In this study, we investigated MDM2 amplification by quantitative PCR and fluorescence in situ hybridization (FISH) together with the SNP309 genotypes, and analyzed the correlations with TP53 and KRAS mutations and clinicopathological features in 211 Japanese CRC patients. MDM2 amplification was detected in 8% of the specimens and its incidence was significantly higher in Dukes' stage C than in the combined earlier Stages A and B (P = 0.025). Unexpectedly, the incidence was significantly decreased in Stage D metastatic disease (P = 0.043). The copy number gain ranged from four to eight copies and was generally concordant with gain of centromere 12 using FISH analysis. Together with the results of centromere 1 FISH and TP53 copy number assessment, the MDM2 increment most likely resulted from chromosome 12 gain. The mechanism of the copy number gain and incidence in Dukes' Stage D differed considerably from the previous report. Ethnic or geographic factors could be responsible for these differences. Several promising therapeutic strategies targeting the TP53-MDM2 system are being developed. Further understanding of the significance of MDM2 and MDM2 amplification in CRC is required to facilitate personalized treatment for CRC patients.

Why target PIM1 for cancer diagnosis and treatment?

The highly conserved proto-oncogenic protein PIM1 is an unusual serine or threonine kinase, in part because it is constitutively active. Overexpression of PIM1 experimentally leads to tumor formation in mice, while complete knockout of the protein has no observable phenotype. It appears to contribute to cancer development in three major ways when it is overexpressed; by inhibiting apoptosis, by promoting cell proliferation and by promoting genomic instability. Expression in normal tissues is nearly undetectable. However, in hematopoietic malignancies and in a variety of solid tumors, increased PIM1 expression has been shown to correlate with the stage of disease. This characteristic suggests it can serve as a useful biomarker for cancer diagnosis and prognosis. Several specific and potent inhibitors of PIM1’s kinase activity have also been shown to induce apoptotic death of cancer cells, to sensitize cancer cells to chemotherapy and to synergize with other anti-tumor agents, thus making it an attractive therapeutic target.

p14ARF promoter region methylation as a marker for gliomas diagnosis

Methylation in the promoter region is one of the mechanisms through which tumor suppressors are inactivated, resulting in tumorigenesis and/or tumor progression. Herein, we studied the methylation status in the promoter region of the p14ARF tumor suppressor gene in 33 brain tissues isolated from glioma patients (astrocytomas) and compared to 12 brain tissues isolated from autopsy donors using methylation-specific polymerase chain reaction (MSP). The correlation between the expression of P14 and P53 was investigated using immunohistochemistry (IHC). The average percentage of methylation in the promoter region of p14ARF gene in brain samples from glioma patients is 39.4%, while 0 from autopsy donors. No difference in the methylation level between low-grade and high-grade gliomas was detected. The methylation status has no correlation with the prognosis in glioma patients. A significant correlation between the expression of mutant form of TP53 and the grade of the glioma was established. Furthermore, there was a negative correlation between methylation of the p14ARF promoter and the expression of the mutant form of TP53. Therefore, our data suggest that methylation in the promoter region of the p14ARF gene may be used as a biomarker for the diagnosis of gliomas.

Molecular prognostic factors in rectal cancer treated by preoperative chemoradiotherapy

The present study evaluated the expression of p53, pRb, hMLH1 and MDM2 prior to preoperative chemoradiotherapy (CRT) in patients with rectal cancer, and attempted to determine any correlation with treatment outcome. Forty-five patients with available pretreatment biopsy tissues and who received preoperative CRT were enrolled in this study. Preoperative CRT consisted of a median 50.4 Gy and 2 cycles of concurrent administration of 5-fluorouracil + leucovorin. Surgery was performed approximately seven weeks after CRT. Protein expression in formalin-fixed paraffin-embedded biopsy specimens was assessed by immunohistochemistry. A positive expression of p53, pRb, hMLH1 and MDM2 was found in 40, 46.7, 40 and 66.7% of the tissue specimens, respectively. The 5-year overall (OS), disease-free (DFS) and locoregional recurrence-free survival (LRFS) rates for patients included in the study were 71.3, 66.1 and 60.9%, respectively. p53 expression presented a significantly different OS (positive vs. negative, 45.8 vs. 86.2%; p=0.02). However, the expression of pRb, hMLH1 and MDM2 was not significant for OS. The expression of p53 was a borderline significant prognostic factor for DFS and for LRFS. Age, p53 and MDM2 expression were significant factors in the multivariate analysis performed for OS with 12 covariates, including 8 clinicopathological parameters and 4 proteins. No significant factor affected DFS or LRFS in the multivariate analysis. We suggest that the expression of p53 is a potential marker of survival. Determinations of this protein expression may be useful for selecting candidates from rectal cancer patients for more tailored treatment.