Prognostic significance of p21 and p53 expression in gastric cancer

Design, Synthesis, and Antitumor Evaluation of an Opioid Growth Factor Bioconjugate Targeting Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) presents a formidable challenge with high lethality and limited effective drug treatments. Its heightened metastatic potential further complicates the prognosis. Owing to the significant toxicity of current chemotherapeutics, compounds like [Met5]-enkephalin, known as opioid growth factor (OGF), have emerged in oncology clinical trials. OGF, an endogenous peptide interacting with the OGF receptor (OGFr), plays a crucial role in inhibiting cell proliferation across various cancer types. This in vitro study explores the potential anticancer efficacy of a newly synthesized OGF bioconjugate in synergy with the classic chemotherapeutic agent, gemcitabine (OGF-Gem). The study delves into assessing the impact of the OGF-Gem conjugate on cell proliferation inhibition, cell cycle regulation, the induction of cellular senescence, and apoptosis. Furthermore, the antimetastatic potential of the OGF-Gem conjugate was demonstrated through evaluations using blood platelets and AsPC-1 cells with a light aggregometer. In summary, this article demonstrates the cytotoxic impact of the innovative OGF-Gem conjugate on pancreatic cancer cells in both 2D and 3D models. We highlight the potential of both the OGF-Gem conjugate and OGF alone in effectively inhibiting the ex vivo pancreatic tumor cell-induced platelet aggregation (TCIPA) process, a phenomenon not observed with Gem alone. Furthermore, the confirmed hemocompatibility of OGF-Gem with platelets reinforces its promising potential. We anticipate that this conjugation strategy will open avenues for the development of potent anticancer agents.

The Role of P21 Protein Expression in Predicting Progression and Biological Behaviors of Gastric Adenocarcinomas

Background: P21 protein is a cyclin-dependent kinase inhibitor and has a crucial function as a cell cycle regulator in malignant tissues. Thus, its association with aggressive characteristics of malignant lesions is suggested. Objectives: We evaluated the expression level of P21 in gastric cancers and its association with the histopathological findings of cancer. Methods: This cross-sectional study was performed on gastric adenocarcinomas from radical gastrectomy. The histopathological examination was assessed by Hematoxylin & Eosin. The immunohistochemistry technique was then used to assess the expression of the P21 marker. Results: P21 positivity was revealed in 28 specimens of the cancerous lesions with an overall prevalence of 70.0% in our population. There was no association between P21 positivity and tumor-related characteristics, including tumor location, type, grade and stage, as well as the size of the cancerous lesion. P21 positivity could not be related to perineural or lymphovascular invasion of the tumor (P-value > 0.05). Conclusions: In our population, the expression of P21 may not be prognostic or predict tumor biological behavior among patients with gastric adenocarcinomas.

p15INK4B is an alternative marker of senescent tumor cells in colorectal cancer

Senescent tumor cells are nonproliferating tumor cells which are closely related to cancer progression by secreting senescence-related molecules, called senescence-associated secreting phenotypes. Therefore, the presence of senescent tumor cells is considered a prognostic factor in various cancer types. Although senescence-associated β-galactosidase staining is considered the best marker for detection of senescent tumor cells, it can only be performed in fresh-frozen tissues. p16^INK4A, a cyclin-dependent inhibitor, has been used as an alternative marker to detect senescent tumor cells in formalin-fixed paraffin-embedded tissues. However, other reliable markers to detect senescent tumor cells is still lacking. In the present study, using public single-cell RNA-sequencing data, we found that p15^INK4B, a cyclin-dependent kinase inhibitor, is a novel marker for detection of senescent tumor cells. Moreover, p15^INK4B expression was positively correlated with that of p16^INK4A in colorectal cancer tissues. In in vitro studies, mRNA expression of p15^INK4B was increased together with that of p16^INK4A in H₂O₂- and therapy-induced cancer senescence models. However, the mRNA level of p15^INK4B did not increase in the oncogene-induced senescence model in primary colonic epithelial cells. In conclusion, p15^INK4B is a potential alternative marker for detection of senescent tumor cells together with conventional markers in advanced stages of colorectal cancer.

Clinicopathological profile and its association with peritoneal disease among gastric cancer patients

BACKGROUND

There are no clinicopathological criteria or test to predict peritoneal metastasis either in primary or recurrent gastric cancer. The early prediction will help in altering or adding other adjuvant potential therapy modalities like HIPEC and maintenance chemotherapy.

METHODS

Paraffin based blocks of 110 gastric tumor specimens were subjected to IHC staining to assess VEGF, Her 2 neu, E cadherin, bcl 2 and p 53 expression and its association with peritoneal disease evaluated.

RESULTS

Her 2 neu uptake was present in 17.3%, bcl-2 expression in 19.1%, P53 expression in 40.9%, VEGF in 41.8% and E cadherin expression in 49.1% patients. On univariate analysis, a younger age(p = .029), female sex(p = .026), positive VEGF expression (p = .001) and p53 expression(p = .015) were significantly associated with peritoneal disease. A binomial logistic regression was performed to ascertain the effects of independent variables evaluated on univariate analysis. Of the 10 predictors variables, only three were statistically significant: tumor type, P53, and VEGF. Positive VEGF expression had 48.7, E cadherin 2.6 and Her2neu 1.5 times higher odds of exhibiting peritoneal disease.

CONCLUSION

A younger age, female sex, distal 2/3rd, diffuse variant, VEGF staining in >10% cells and decrease p53 expression were associated with peritoneal disease.

Signaling Pathways in Cancer: Therapeutic Targets, Combinatorial Treatments, and New Developments

Molecular alterations in cancer genes and associated signaling pathways are used to inform new treatments for precision medicine in cancer. Small molecule inhibitors and monoclonal antibodies directed at relevant cancer-related proteins have been instrumental in delivering successful treatments of some blood malignancies (e.g., imatinib with chronic myelogenous leukemia (CML)) and solid tumors (e.g., tamoxifen with ER positive breast cancer and trastuzumab for HER2-positive breast cancer). However, inherent limitations such as drug toxicity, as well as acquisition of de novo or acquired mechanisms of resistance, still cause treatment failure. Here we provide an up-to-date review of the successes and limitations of current targeted therapies for cancer treatment and highlight how recent technological advances have provided a new level of understanding of the molecular complexity underpinning resistance to cancer therapies. We also raise three basic questions concerning cancer drug discovery based on molecular markers and alterations of selected signaling pathways, and further discuss how combination therapies may become the preferable approach over monotherapy for cancer treatments. Finally, we consider novel therapeutic developments that may complement drug delivery and significantly improve clinical response and outcomes of cancer patients.

Therapeutic strategies to overcome taxane resistance in cancer

One of the primary causes of attenuated or loss of efficacy of cancer chemotherapy is the emergence of multidrug resistance (MDR). Numerous studies have been published regarding potential approaches to reverse resistance to taxanes, including paclitaxel (PTX) and docetaxel, which represent one of the most important classes of anticancer drugs. Since 1984, following the FDA approval of paclitaxel for the treatment of advanced ovarian carcinoma, taxanes have been extensively used as drugs that target tumor microtubules. Taxanes, have been shown to affect an array of oncogenic signaling pathways and have potent cytotoxic efficacy. However, the clinical success of these drugs has been restricted by the emergence of cancer cell resistance, primarily caused by the overexpression of MDR efflux transporters or by microtubule alterations. In vitro and in vivo studies indicate that the mechanisms underlying the resistance to PTX and docetaxel are primarily due to alterations in α-tubulin and β-tubulin. Moreover, resistance to PTX and docetaxel results from: 1) alterations in microtubule-protein interactions, including microtubule-associated protein 4, stathmin, centriole, cilia, spindle-associated protein, and kinesins; 2) alterations in the expression and activity of multidrug efflux transporters of the ABC superfamily including P-glycoprotein (P-gp/ABCB1); 3) overexpression of anti-apoptotic proteins or inhibition of apoptotic proteins and tumor-suppressor proteins, as well as 4) modulation of signal transduction pathways associated with the activity of several cytokines, chemokines and transcription factors. In this review, we discuss the abovementioned molecular mechanisms and their role in mediating cancer chemoresistance to PTX and docetaxel. We provide a detailed analysis of both in vitro and in vivo experimental data and describe the application of these findings to therapeutic practice. The current review also discusses the efficacy of different pharmacological modulations to achieve reversal of PTX resistance. The therapeutic roles of several novel compounds, as well as herbal formulations, are also discussed. Among them, many structural derivatives had efficacy against the MDR phenotype by either suppressing MDR or increasing the cytotoxic efficacy compared to the parental drugs, or both. Natural products functioning as MDR chemosensitizers offer novel treatment strategies in patients with chemoresistant cancers by attenuating MDR and increasing chemotherapy efficacy. We broadly discuss the roles of inhibitors of P-gp and other efflux pumps, in the reversal of PTX and docetaxel resistance in cancer cells and the significance of using a nanomedicine delivery system in this context. Thus, a better understanding of the molecular mechanisms mediating the reversal of drug resistance, combined with drug efficacy and the application of target-based inhibition or specific drug delivery, could signal a new era in modern medicine that would limit the pathological consequences of MDR in cancer patients.

Smart Nanoformulation Based on Polymeric Magnetic Nanoparticles and Vincristine Drug: A Novel Therapy for Apoptotic Gene Expression in Tumors

Background: Advanced nanobiotechnology provides safe and efficient drug delivery systems to deliver chemotherapy that targets cancer cells efficiently. Methods: A polymeric-magnetic nanocarrier was composed of a dextran (DEX) shell, a superparamagnetic iron oxide (SPION) core and was conjugated with folate (FA) to carry the anticancer drug vincristine (VNC) in Tera-1 testicular tumor cells. The molecular mechanisms by which apoptosis was induced were analyzed using flow cytometry and qPCR, which exhibited anticancer activity of nanoparticles (NPs). Results: This nanocarrier revealed a controlled release of VNC in citrate and phosphate buffer solutions that were maintained at pH 5.5 and pH 7.4, respectively. The Inhibitory concentration (IC50) values were greater than 5 mg/mL and displayed ten times higher cytotoxicity than the comparable free drug concentration. The Caspase-9 and P53 expressions were increased, whereas P21 and AKt1 decreased noticeably in the treated cells. The results point to the possible activation of apoptosis following treatment with NPs loaded with vincristine.

p53, Cyclin-D1, β-catenin, APC and c-myc in Tumor Tissue from Colorectal and Gastric Cancer Patients with Suspected Lynch Syndrome by the Bethesda Criteria

Colorectal cancer (CRC) is one of the most frequent neoplasms worldwide, and up to 15% have a family history. Lynch syndrome (LS) is a hereditary cause of CRC and gastric (GC). Individuals with LS have mutations in mismatch genes repair. p53, cyclin D1, β-catenin, APC and c-myc proteins are involved in the cell cycle and carcinogenesis.

PRIMA-1MET Induces Cellular Senescence and Apoptotic Cell Death in Cholangiocarcinoma Cells

BACKGROUND/AIM

This study examined the in vitro effects of the bile duct cancer drug PRIMA-1^MET on cholangiocarcinoma (CCA) cell growth to determine its potential usefulness in CCA therapy.

MATERIALS AND METHODS

The effect of this drug on the expression of senescent markers (p16^INK4A and p21) and the phosphorylation of p53 was investigated, as was the association between senescent markers and the patients' clinicopathological data.

RESULTS

PRIMA-1^MET inhibited CCA cell growth with the half maximal-inhibitory concentration (IC₅₀) values of 21.9-40.8 μM. PRIMA-1^MET induced phospho-p53, p16^INK4A and p21 triggering cellular senescence and apoptosis. High expressions of p16^INK4A and p21 were associated with a high survival rate of patients with CCA.

CONCLUSION

PRIMA-1^MET may potentially be an alternative anticancer agent that might lead to a better prognosis in patients with CCA.

Tumor growth suppressive effect of IL-4 through p21-mediated activation of STAT6 in IL-4Rα overexpressed melanoma models

To evaluate the significance of interleukin 4 (IL-4) in tumor development, we compared B16F10 melanoma growth in IL-4-overespressing transgenic mice (IL-4 mice) and non-transgenic mice. In IL-4 mice, reduced tumor volume and weight were observed when compared with those of non-transgenic mice. Significant activation of DNA binding activity of STAT6, phosphorylation of STAT6 as well as IL-4, IL-4Rα and p21 expression were found in the tumor tissues of IL-4 mice compared to non-transgenic mice. Higher expression of IL-4, STAT6 and p21 in human melanoma tissue compared to normal human skin tissue was also found. Higher expression of apoptotic protein such as cleaved caspase-3, cleaved caspase-8, cleaved caspase-9, Bax, p53 and p21, but lower expression levels of survival protein such as Bcl-2 were found in the tumor of IL-4 mice. In vitro study, we found that overexpression of IL-4 significantly inhibited SK-MEL-28 human melanoma cell and B16F10 murine melanoma cell growth via p21-mediated activation of STAT6 pathway as well as increased expression of apoptotic cell death proteins. Moreover, p21 knockdown with siRNA abolished IL-4 induced activation of STAT6 and expression of p53 and p21 accompanied with reduced IL-4 expression as well as melanoma cell growth inhibition. Therefore, these results showed that IL-4 overexpression suppressed tumor development through p21-mediated activation of STAT6 pathways in melanoma models.

The p53/p21 Complex Regulates Cancer Cell Invasion and Apoptosis by Targeting Bcl-2 Family Proteins

The tumor suppressor p53 binds prosurvival Bcl-2 family proteins such as Bcl-w and Bcl-X_L to liberate Bax, which in turn exerts proapoptotic or anti-invasive functions depending on stress context. On the basis of our previous finding that p53 interacts with p21, we investigated the possible involvement of p21 in these functions. Here, we report that although p53 can bind Bcl-w alone, it requires p21 to liberate Bax to suppress cell invasion and promote cell death. p21 bound Bcl-w, forming a p53/p21/Bcl-w complex in a manner that maintained all pairwise p53/p21, p21/Bcl-w, and p53/Bcl-w interactions. This allowed Bax liberation from the complex. Accordingly, a p53 derivative incapable of binding p21 failed to mediate radiotherapy-induced tumor cell death in mice. Bcl-X_L also served as a target of the cooperative action of p53 and p21. Overall, our findings indicate that the p53/p21 complex rather than p53 itself regulates cell invasion and death by targeting Bcl-2 proteins. We propose that the p53/p21 complex is a functional unit that acts on multiple cell components, providing a new foundation for understanding the tumor-suppressing functions of p53 and p21. Cancer Res; 77(11); 3092-100. ©2017 AACR.

Optimization and Corroboration of the Regulatory Pathway of p42.3 Protein in the Pathogenesis of Gastric Carcinoma

AIMS

To optimize and verify the regulatory pathway of p42.3 in the pathogenesis of gastric carcinoma (GC) by intelligent algorithm.

METHODS

Bioinformatics methods were used to analyze the features of structural domain in p42.3 protein. Proteins with the same domains and similar functions to p42.3 were screened out for reference. The possible regulatory pathway of p42.3 was established by integrating the acting pathways of these proteins. Then, the similarity between the reference proteins and p42.3 protein was figured out by multiparameter weighted summation method. The calculation result was taken as the prior probability of the initial node in Bayesian network. Besides, the probability of occurrence in different pathways was calculated by conditional probability formula, and the one with the maximum probability was regarded as the most possible pathway of p42.3. Finally, molecular biological experiments were conducted to prove it.

RESULTS

In Bayesian network of p42.3, probability of the acting pathway "S100A11→RAGE→P38→MAPK→Microtubule-associated protein→Spindle protein→Centromere protein→Cell proliferation" was the biggest, and it was also validated by biological experiments.

CONCLUSIONS

The possibly important role of p42.3 in the occurrence of gastric carcinoma was verified by theoretical analysis and preliminary test, helping in studying the relationship between p42.3 and gastric carcinoma.

Molecular biomarkers in esophageal, gastric, and colorectal adenocarcinoma

Cancers of the esophagus, stomach and colon contribute to a major health burden worldwide and over 20% of all cancer deaths. Biomarkers that should indicate pathogenic process and are measureable in an objective manner for these tumors are rare and not established in the clinical setting. In general biomarkers can be very useful for cancer management as they can improve clinical decision-making regarding diagnosis, surveillance, and therapy. Biomarkers can be different types of molecular entities (such as DNA, RNA or proteins), which can be detected, in different tissues or body fluids. However, more important is the type of biomarker itself, which allows diagnostic, prognostic or predictive analyses for different clinical problems. This review aims to systematically summarize the recent findings of genetic and epigenetic markers for gastrointestinal tumors within the last decade. While many biomarkers seem to be very promising, especially if used as panels, further development is urgently needed to address practical considerations of biomarkers in cancer treatment.

The prognostic significance of p21 and Her-2 gene expression and mutation/polymorphism in patients with gastric adenocarcinoma

Analyses of gene expression status and genetic polymorphisms are methods to identify novel histopathological prognostic factors. In patients with gastric cancer, some cell cycle regulators p53, p21, p27 and Her-2 oncogene have been proposed as prognostic factors. We aimed to investigate the expression and mutation/polymorphism of p21 and Her-2 and also relationship between that genes status and histopathological factors and prognosis in patients with gastric cancer. Forty-four patients with locally advanced gastric cancer were analyzed in this study from January 2000 to December 2008. Clinicopathological parameters, expression and mutation/polymorphism of p21 and Her-2 results were used to predict disease-free survival and overall survival. The positive expression of p21 and Her-2 was observed in 61.4 % (n = 27) and 9.1 % (n = 4) of all 44 tumors, respectively. p21 gene mutation and Her-2 gene polymorphism were detected in 20 % (n = 11) and 2.3 % (n = 1, II phenotype) of cases, respectively. The negative expression of p21 was correlated significantly with diffuse and undifferential type histologies, whole gastric involvement and positive vascular/neural invasion. The median survival rate of patients with negative expression was significantly poorer than that of patients with positive expression of p21 (17 vs. 27 months, p = 0.01, cox regression). p21 mutation was significantly higher in patients with diffuse (p = 0.03) and undifferential (p = 0.02) type histologies. There was no statistically significant association between histopathological parameters and Her-2 gene polymorphism/expression. The negative expression of p21 correlates with disease survival and may be a poor prognostic factor in patients with resected gastric cancer treated with adjuvant chemotherapy.

The overexpression of AP-4 as a prognostic indicator for gastric carcinoma

As a transcription factor belonging to the basic helix-loop-helix leucine-zipper subgroup, AP-4 can control target gene expression by altering cell signal transduction, and regulate growth, development, and cell apoptosis. Under pathological circumstances, it is involved in tumorigenesis. Herein, immunohistochemistry and real-time PCR were used to detect the transcription factor AP-4 expression in gastric cancer, and these data were examined for correlation with histology, pTNM stage, and prognosis. The AP-4 expression rate was 83.67% in a total of 98 gastric cancer tissues, which was significantly higher than 40.91% in non-neoplastic tissues; AP-4 mRNA relative expression shows a significant difference between gastric cancer and normal tissues, and AP-4 expression has a significantly positive correlation with the depth of tumor invasion (P < 0.0001), degree of tumor differentiation (P = 0.0058), lymph node metastasis (P = 0.0255), and pTNM stage (P = 0.001). Survival analysis showed that AP-4-positive patients' median survival time (12.60 months) was significantly shorter than that (41.40 months) of AP-4-negative patients. AP-4 expression in gastric cancer is associated with clinicopathological parameters of gastric cancer, such as differentiation, lymph node metastasis, depth of invasion (P = 0.0010), and pTNM stage. What's more, AP-4 overexpression indicated a worse prognosis for patients. So AP-4 may be a molecular marker to predict the progression and prognosis of the tumor.

Genomic and genetic alterations influence the progression of gastric cancer

Gastric cancer is one of the leading causes of cancer-related deaths worldwide, although the incidence has gradually decreased in many Western countries. Two main gastric cancer histotypes, intestinal and diffuse, are recognised. Although most of the described genetic alterations have been observed in both types, different genetic pathways have been hypothesized. Genetic and epigenetic events, including 1q loss of heterozygosity (LOH), microsatellite instability and hypermethylation, have mostly been reported in intestinal-type gastric carcinoma and its precursor lesions, whereas 17p LOH, mutation or loss of E-cadherin are more often implicated in the development of diffuse-type gastric cancer. In this review, we summarize the sometimes contradictory findings regarding those markers which influence the progression of gastric adenocarcinoma.

Canine gastric carcinoma: immunohistochemical expression of cell cycle proteins (p53, p21, and p16) and heat shock proteins (Hsp27 and Hsp70)

Immunohistochemical staining for cell cycle proteins and heat shock proteins was performed on 17 canine gastric carcinomas. The immunoexpression of p53, p21, p16, Hsp27, and Hsp70 was investigated. A study was conducted to determine the histological type and parameters related to tumor malignancy. Possible associations and trends were assessed between the immunoexpression of each protein and tumor type as well as specific parameters of malignancy. High intratumor frequency of cellular p53 immunostaining was observed (61.96% average), but lower frequencies of p21 and p16 expression were present (34.65% and 10.41%, respectively). The p53 overexpression was associated with tumor infiltration (P = .0258). Expression of p21 was lower in undifferentiated carcinomas, and the loss of expression was associated with histopathological parameters characteristic of a poor prognosis such as lymphatic vessel invasion (P = .0258). The lack of p16 immunoreactivity was related to histopathological characteristics of malignancy such as the presence of evident and multiple nucleoli (P = .0475). In contrast, deep tumor infiltration was observed in those carcinomas with a high p16 index (P = .0475). Hsp70 appeared to be overexpressed in all gastric neoplasms included in this study. This is in contrast to Hsp27, because a group of tumors showed complete lack of Hsp27 immunoexpression, whereas the others displayed extensive Hsp27 immunostaining. The differences in Hsp27 did not correlate with any of the histopathological parameters, but Hsp27 immunoexpression was higher in the undifferentiated carcinoma. No significant differences in the expression of the proteins were found in canine gastric carcinomas according to their histological type. These findings may be useful for establishing a prognosis for canine gastric carcinoma.

Correlation between expression of p53, p21/WAF1, and MDM2 proteins and their prognostic significance in primary hepatocellular carcinoma

Background

Tumor Protein p53 (p53), cyclin-dependent kinase inhibitor 1A (p21/WAF1), and murine double minute 2 (MDM2) participate in the regulation of cell growth. Altered expression of these gene products has been found in malignant tumors and has been associated with poor prognosis. Our aim was to investigate the expression of the 3 proteins in hepatocellular carcinoma (HCC) and their prognostic significance.

Methods

We examined p53, p21/WAF1, and MDM2 expression in 181 pairs of HCC tissues and the adjacent hepatic tissues by performing immunohistochemistry and examined the expression of the 3 proteins in 7 pairs of HCC tissues and the adjacent hepatic tissues by using western blot analysis.

Results

The expression of p53, p21/WAF1, and MDM2 in the HCC tissues was significantly higher than those in the adjacent hepatic tissues (P < 0.05). A statistical correlation was observed between p53 and p21/WAF1 expression in HCC tissues (R = 0.195, P = 0.008). A statistical correlation was observed between expression of p53 and p21/WAF1 (R = 0.380, P = 0.000), p53 and MDM2 (R = 0.299, P = 0.000), p21/WAF1 and MDM2 (R = 0.285, P = 0.000) in 181 liver tissues adjacent to the tumor. Patients with a low pathologic grade HCC (I+II) had a higher tendency to express p53 on tumor cells than the patients with high pathologic grade HCC (III+IV) (P = 0.007). Survival analysis showed that positive p21/WAF1 expression or/and negative MDM2 expression in HCC was a predictor of better survival of patients after tumor resection (P < 0.05).

Conclusions

The proteins p53, p21/WAF1, and MDM2 were overexpressed in all the HCC cases in this study, and p53 and p21/WAF1 overexpression were positively correlated. The expression of p21/WAF1 and MDM2 can be considered as 2 useful indicators for predicting the prognosis of HCC.

Prognostic implications of p21 (Waf1/Cip1) immunolocalization in multiple myeloma

Protein p21 (Waf1/Cip1) plays a critical role in controlling the cell cycle especially as a check point of G1 and is intimately associated with important cellular activities including differentiation, senescence, tumorigenesis, and apoptosis. In the present study, we examined the expression of p21 in multiple myeloma (MM) cells for prognostic evaluation. The immunocytochemical localization of p21 could be categorized into nuclear and cytoplasmic types. The nuclear-type p21 localization was correlated with the severity of MM and the expression of proliferating cell nuclear antigen and p53. Patients with the nuclear-type p21 localization survived significantly shorter than those with the cytoplasmic-type localization. Thus, the present study suggests that p21-immunolocalization can be a useful prognostic marker of MM.

Lycopene supplementation prevents smoke-induced changes in p53, p53 phosphorylation, cell proliferation, and apoptosis in the gastric mucosa of ferrets

Cigarette smoking increases the risk for gastric cancer. Higher intakes or blood levels of lycopene are associated with a decreased risk of gastric cancer. However, the biological mechanisms by which lycopene may protect against gastric carcinogenesis are poorly understood. We evaluated the effects of lycopene supplementation on smoke-induced changes in protein levels of p53, p53 target genes (p21(Waf1/Cip1) and Bax-1), cell proliferation, and apoptosis in the gastric mucosa of ferrets. Ferrets were assigned to cigarette smoke exposure or to no exposure and to no, low-dose, or high-dose lycopene supplementation (2 x 3 factorial design) for 9 wk. Lycopene concentrations were significantly elevated in a dose-dependent manner in the gastric mucosa of ferrets supplemented with lycopene alone, but were markedly reduced in ferrets supplemented with lycopene and exposed to smoke. Although ferrets were given lycopene containing 95% all-trans isomers, cis isomers were the predominant forms in the gastric mucosa. Total p53 and phosphorylated p53 levels were greater in ferrets exposed to smoke alone than in all other groups. Levels were approximately 300 and 500% of the controls, respectively. However, smoke-elevated total p53 and phosphorylated p53 were markedly attenuated by both doses of lycopene. p21(Waf1/Cip1), Bax-1, and cleaved caspase 3 were substantially decreased, whereas cyclin D1 and proliferating cellular nuclear antigen (PCNA) were increased in ferrets exposed to smoke alone. Lycopene prevented smoke-induced changes in p21(Waf1/Cip1), Bax-1, cleaved caspase 3, cyclin D1, and PCNA in a dose-dependent fashion. These data indicate that lycopene may prevent smoke exposure-induced changes in p53, p53 phosphorylation, p53 target genes, cell proliferation, and apoptosis in the gastric mucosa of ferrets.

Epstein-Barr virus and aberrant expression of mdm2 and p53 in pathogenesis and development of gastric carcinoma

AIM: To investigate the role of p53 and mdm2 gene abnormality in oncogenesis and development of Epstein-Barr virus (EBV) -associated gastric carcinoma (EBVaGC) and to explore the relationship between EBV infection and p53 and mdm2 protein expression.

METHODS: p53 gene mutation in exon 5-8 was detected by polymerase chain reaction and single strand conformation polymorphism analysis (PCR-SSCP), and DNA sequencing. p53 and mdm2 protein expression was tested by immunohistochemistry in EBVaGCs (n = 13), EBVnGCs (EBV negative gastric carcinomas, n = 45) with matched clinicopathological parameters and corresponding adjacent tissues of gastric carcinoma (n = 58).

RESULTS: The positive rates of p53 and mdm2 protein in gastric carcinomas were significantly higher than those in corresponding adjacent normal tissues (86.2%, 29.3% vs 0%, 0% respectively; P < 0.01). There were no significant difference between the positive rates of p53 and mdm2 protein in EBVnGCs and EBVaGCs. The overexpression rate of p53 protein was 15.4% (2/13) in EBVaGCs. This was in marked contrast to the rate of 57.8% (26/45) in EBVnGCs (χ² = 7.2593, P = 0.0 085 < 0.01). There was significant positive correlation between mdm2 expression and p53 overexpression (χ² = 11.1 839, P = 0.0 008 < 0.01, r = 0.4 391). p53 gene mutation was found in only 2 cases of EBVnGCs and both occurred at exon 5. No p53 gene mutation was detected in 13 cases of EBVaGCs and 58 corresponding adjacent tissues.

CONCLUSION: Abnormal accumulation of p53 protein might not result from p53 gene mutation. mdm2 protein may play an important role in the pathogenesis of gastric carcinoma through suppressing the function of wild type p53 protein. The infection of EBV relates to the abnomal expression of p53 protein, but not to the abnomal expression of mdm2 protein and p53 gene mutation in gastric carcinoma

Expression of p21(WAF1) and p53 and polymorphism of p21(WAF1) gene in gastric carcinoma

AIM

To investigate the relationship between expression of p21(WAF1) and p53 gene, and to evaluate the deletion and polymorphism of p21(WAF1) gene in gastric carcinoma (GC).

METHODS

Expression of p21 and p53 proteins, and deletion and polymorphism of p21 gene in GC were examined by streptavidin-peroxidase conjugated method (SP) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) respectively.

RESULTS

The expression of p21 and p53 was found in 100% (20/20) and 0% (0/20) of normal gastric mucosae(NGM), 92.5% (37/40) and 15.0% (6/40) of dysplasia (DP) and 39.8% (43/108) and 56.5% (61/108) of GC, respectively. The positive rate of p21 in GC was lower than that in NGM and DP (P<0.05), while the positive rate of p53 in GC was higher than that in NGM and DP (P<0.05). p21 and p53 were significantly expressed in 63.3% (19/30) and 36.7% (11/30), 35.0% (14/40) and 77.5% (31/40), 26.7% (4/15) and 80.0% (12/15), 30.8% (4/13) and 30.8% (4/13), and 20.0% (2/10) and 30.0% (3/10) of well-differentiated, poorly-differentiated, undifferentiated carcinomas, mucoid carcinomas and signet ring cell carcinomas. The expression of p21 in well-differentiated carcinomas was significantly higher than that in poorly-differentiated, un-differentiated, mucoid carcinomas and signet ring cell carcinomas (P<0.05). Contrarily, The expression of p53 was increased from well-differentiated to poorly-differentiated and un-differentiated carcinomas (P<0.05). The expression of p21 and p53 in paired primary and metastatic GC (35.3% and 70.6%) was different from non-metastatic GC (62.5% and 42.5%) markedly (P<0.05). The expression of p21 in invasive superficial muscle (60.0%) was higher than that in invasive deep muscle or total layer (35.2%) (P<0.05) and was higher in TNM stages I (60.0%) and II (56.2%) than in stages III (27.9%) and IV (22.2%) (P<0.05), whereas the expression of p53 did not correlate to invasion depth or TNM staging (P>0.05). The exoression patterns of p53+/p21-, and of p53-/p21+ were found in 5.0% and 82.5% of DP. There was a significant correlation between expression of p21 and p53 (P<0.05). But there was no significant correlation between expression of both in GC (P>0.05). There was no deletion in exon 2 of p21 gene in 30 cases of GC and 45 cases of non-GC, but polymorphism of p21 gene at exon 2 was found in 26.7% (8/30) of GC and 8.9% (4/45) of non-GC, a significant difference was found between GC and non-GC (P<0.05). There was no significant relation between p21 expression of polymorphism (37.5%, 3/8) and non-polymorphism (45.5%, 10/22) in GC (P>0.05).

CONCLUSION

The loss of p21 protein and abnormal expression of p53 are related to carcinogenesis, differentiation and metastasis of GC. The expression of p21 is related to invasion and clinical staging in GC intimately. The expression of p21 protein depends on p53 protein largely in NGM and DP, but not in GC. No deletion of p21 gene in exon 2 can be found in GC. The polymorphism of p21 gene might be involved in gastric carcinogenesis.There is no significant association between polymorphism of p21 gene and expression of p21 protein.

Cell cycle and no end

Our knowledge about the molecular circuits regulating the duplication of the genetic material and the subsequent division of a cell into two daughter cells has exploded over the last decade. Aberrations in the regulation of the cell cycle belong to the hallmarks of malignant transformation, leading, in turn, to the development of tumours. After introducing the basics of eukaryotic cell-cycle regulation and describing the four phases of the cell cycle (namely, G1, S, G2 and M) in more detail, alterations of key components of the cell-cycle machinery in human malignancies and their functional consequences are presented. Principally, deregulation of the cell cycle can be caused by unrestricted activity of cell-cycle promoting factors (many oncogenes fall into this class) or by inactivation of inhibitory factors (many tumour suppressor genes belong to this class). Both types of deregulation have been described in human tumours and are discussed in detail. Perspectives concerning the translation of this knowledge into daily routine practice and future applications are discussed at the end. The molecular mechanisms of actual cell division (sister chromatid segregation and cytokinesis) are mentioned only briefly.