P53 Gene Alterations Research Articles

Analysis of single nucleotide polymorphism of p16 gene in cytological samples of patients with oral potentially malignant disorders (OPMD) and oral squamous cell carcinoma (OSCC)

Backgroundpl6 (CDKN2a) play a role in tumorigenesis in some head and neck squamous cell carcinomas. Frequent homozygous deletions of the pl6 gene have been reported in many tumor cell lines including the brain, breast, osteosarcomas, melanomas, kidney, bladder, and ovary. Materials and methods5 patients without any tobacco using habit were included in group I as controls. 10 clinically and histopathologically confirmed cases of oral potentially malignant disorders (OPMDs) [oral submucous fibrosis (OSMF) −7 & leukoplakia (moderate dysplasia) −3] were included in group II. 10 clinically and histopathologically confirmed cases of OSCC were categorized as group III. Buccal scrapings were taken and analyzed for exon 1, 2, 3 of p16 and homozygous deletion in exon 2 of p16 was also detected by PCR and gel electrophoresis. ResultsPCR amplification products of exon 1, 2, 3 of p16 were found in all 25 samples which include 10 cases of OSCC, 10 cases of OPMDs and 5 controls. Homozygous deletion in exon 2 was found only in 30 % of OSCC and 20 % of OPMD. ConclusionOur study showed that cytological samples yield sufficient amount of DNA, which showed 100 % positivity with exon 1, 2, 3 of p16 gene, but the percentage of genetic alteration of p16 gene seems to be less when compared with other related studies.

The genetic duet of concurrent RASAL1 and PTEN alterations promotes cancer aggressiveness by cooperatively activating the PI3K-AKT pathway.

The significance of the prominent tumor suppressor gene for RAS protein activator-like 1 (RASAL1) could be better understood by combined genetic, clinical, and functional studies. Here, we investigated the oncogenic and clinical impacts of genetic alterations of RASAL1, particularly when coexisting with genetic alterations of the gene for phosphatase and tensin homolog (PTEN), in 9924 cancers of 33 types in the TCGA database. We found common concurrent genetic alterations of the two genes, which were cooperatively associated with activation of the phosphatidylinositol 3-kinase (PI3K)-AKT pathway, with cancer progression and mortality rates being 46.36% and 31.72% with concurrent gene alterations, versus 29.80% and 16.93% with neither gene alteration (HR 1.64, 95% CI 1.46-1.84 and 1.77, 95% CI 1.53-2.05), respectively. This was enhanced by additional tumor protein p53 (TP53) gene alterations, with cancer progression and mortality rates being 47.65% and 34.46% with coexisting RASAL1, PTEN, and TP53 alterations versus 25.30% and 13.11% with no alteration (HR 2.21, 95% CI 1.92-2.56 and 2.76, 95% CI 2.31-3.30), respectively. In the case of breast cancer, this genetic trio was associated with a triple-negative risk of 68.75% versus 3.83% with no genetic alteration (RR 17.94, 95% CI 9.60-33.51), consistent with the aggressive nature of triple-negative breast cancer. Mice with double knockouts of Rasal1 and Pten displayed robust Pi3k pathway activation, with the development of metastasizing malignancies, while single gene knockout resulted in only benign neoplasma. These results suggest that RASAL1, like PTEN, is a critical player in negatively regulating the PI3K-AKT pathway; defect in RASAL1 causes RAS activation, thus initiating the PI3K-AKT pathway signaling, which cannot terminate with concurrent PTEN defects. Thus, the unique concurrent RASAL1 and PTEN defects drive oncogenesis and cancer aggressiveness by cooperatively activating the PI3K-AKT pathway. This represents a robust genetic mechanism to promote human cancer.

Abstract B039: Development of a selective therapeutic intervention for p53 mutant for pancreatic adenocarcinoma

Abstract Genetic alterations in the tumor suppressor p53 gene (TP53) are found in over 70% of Pancreatic Adenocarcinoma (PAAD) and contribute to poor prognosis, cancer progression and metastasis. Existing treatment options for p53 mutant (p53mut) cancer are limited and there is an urgent need for better therapeutic interventions that can be greatly beneficial to a large proportion of patients with PAAD. Here we present a novel therapeutic strategy for selective targeting p53mut pancreatic tumors. Genomic data revealed that p53-deficient PAADs express high levels of DNA replication genes as well as genes involved in Base Excision (BER) and Mismatch (MMR) Repair, indicating activation of these mechanisms. Evaluation of BER activity by a novel methodology with a modified deoxyuridine analogue showed a significant dysregulation in BER mediated repair in p53mut cancer cells leading to accumulation of p53mut tumor cells in late S/G2 phase. By exploiting this defect, we found that treatment with a deoxyuridine analogue such as trifluorothymidine (TFT, a component of TAS102) resulted in accumulation of DNA breaks selectively in p53mut cells. A deoxyuridine analogue (TFT) did not block DNA replication but rather activated DNA repair leading to DNA breaks in p53mut cells whereas p53 wild type cells accumulated in G1 with minimal DNA damage. Further, we found that inhibition of poly (ADP) ribose polymerase (PARP) enhanced DNA damage and increased cell death selectively in p53mut tumor cells although PARP inhibitor alone was not effective. In contrast, the TAS102-PARPi did not induce DNA damage in the normal cells such as hTERT-immortalized Human Pancreatic Nestin Expressing cells (HPNE). A new TAS102-PARPi combination regimen demonstrated greater inhibition of tumor growth and improved the survival rates in p53mut PAAD xenograft models including Cell-Derived Xenograft (CDX) and Patient-Derived xenograft (PDX) models, compared to either drug alone without adverse effects in mice. Thus, this preclinical work identified a novel and immediately feasible strategy for p53mut disease that may improve treatment and the quality of life for a significant proportion of patients with PAAD while limiting toxic effects on normal tissues. Citation Format: Mohammed M. Alruwaili, Justin Zonneville, Mohammed A. Alqarni, Priyanka Rajan, Hannah Serio, Robert Straubinger, Christos Fountzilas, Andrei Bakin. Development of a selective therapeutic intervention for p53 mutant for pancreatic adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr B039.

Methylation of p16 gene and reduced expression of p16 protein in insulinoma associated with clinicopathological features

Objective: To study the alterations of p16 gene and its expression in insulinoma and to correlate the findings with clinicopathological characteristics. Methods: Expression of p16 protein was detected in 72 insulinomas and 49 para-tumoral or normal pancreatic tissues by immunohistochemical staining. Genomic DNA was isolated from 32 tumor tissue and 17 paired pancreatic tissues and bisulfite-modified. Promoter methylation status of p16 gene was detected in 32 tumor tissue and 17 paired pancreatic tissues by methylation specific PCR. The findings were correlated with the clinicopathological features. Results: There were 30 males and 42 females in all 72 patients, aged (46.5±14.0) years. Loss or reduced expression of p16 protein was found in 42 of 72 insulinomas (58.3%) while loss or reduced expression of p16 was seen in only 34.7% (17/49) of para-tumoral or normal pancreatic tissues (χ²=6.52, P=0.011). Promoter methylation of p16 gene was found in 13 of 32 insulinomas (40.6%) and only 2 of 17 (11.8%) para-tumoral tissues (χ²=4.35, P=0.037). The expression of p16 protein in insulinoma was not associated with clinicopathological features such as gender, age, tumor size and tumor grade. Conclusions: Loss or reduced expression of p16 protein was found in insulinomas, and associated with p16 gene promoter methylation.

Alteration of P53, hMLH1, and HER2 Gene in Bangladeshi Gastric Cancer Patients: Their Association with H. pylori Infection and Clinicopathological Factors

Background Gene alterations are required for the development of gastric cancer, which are influenced by environmental and host factors. We conducted the present study to find the status of Helicobacter pylori (H. pylori) infection and its association with altered genes P53, hMLH1, and HER2 in gastric cancer patients and to analyze their correlation with clinical, pathological, and environmental factors.Method This was a cross-sectional study. For genetic (P53 and hMLH1) study of the gastrectomized tissue DNA extraction and optimization, we performed PCR amplification and DNA sequencing. HER2 was studied by immunochemical technique. The results were matched with tumor status, age and sex, smoking, and H. pylori antibody status of the patients to find their association.Results The mean age of the patients was 52.91 (±13.94) years. Among the 45 patients selected for genetic tests, 12 aged 40 or more and 33 aged over 40. Among the genes, 33(73.3%) in P53 and 17(37.7%) in hMLH1 were mutated and 11(24.2%) in HER2 were found to be overexpressed. Chi square and regression analysis showed that they all had associations with H. pylori positivity (P 1). hMLH1 was associated with the location of the tumor, smoking, sex, blood group, and age, and P53 was found to be affected by extra salt intake, sex, blood group, and age of the patients (P ≤ 0.05 ).Conclusion Genetic mutation was found in nearly all the patients with gastric cancer, which was significantly associated with H. pylori infection. Mass eradication of this organism might play a role in reducing cancer incidence in Bangladesh.

Anti-Cancer Effects of Huaier on Prostate Cancer; miRNA-Mediated Transcription Control Induced Both Inhibition of Active Progression and Prevention of Relapse

Prostate cancer is classified as mild malignant tumor, since the growth is slow, and also the early detection and monitoring of PSA and other cancer cell-specific markers are available among the target population in walk-in clinic even effect the bones and lymph nodes, it requires long term treatments which significantly decrease the lifespan in patients. Trametes robiniophila Murr (Huaier) has proved broad spectrum anti-cancer effects, which initiates the recovery of damaged bio physiological functions in the end by dose-dependent manner which proved the molecular basis of Huaier effects by total RNA and small non-coding RNA sequencing (“genome-scope” project) and that is based on the rescue of the disrupted transcriptional control based on individual capability and flexibility of genomic potential. Here we focused to show MEGA-DATA genome analysis results on inhibition of active progression in cancer in situ, and also prevents relapse of prostate cancer. Total sequencing of RNAs revealed massive SNP variances (average 89,473SNP variances per individual), however, it is unlikely that specific type variants influenced to the malignancy, process, and prognosis. On the other hand, the significant up-regulation and alteration of major ontogenesis and tumor suppressor genes were detected in transcribed genes, especially in altered (normalized) NFkB, TGFb, BRCA2 and p53 genes and their leading signaling pathways. These genetic alterations in transcriptomes were based on miRNA-mediated transcriptional control as reported drugs have not shown any effect. Thus, the present study provides the safe and effective treatment to prevent and inhibit prostate cancer progression, and also to maintain homeostasis in a long-range of stressful human life without excessive medical treatments.

Increased Number of Chromosomal Imbalances and High-Level DNA Amplifications in Mantle Cell Lymphoma Are Associated With Blastoid Variants

AbstractMantle cell lymphomas (MCLs) are characterized by 11q13 chromosomal translocations and cyclin D1 overexpression. The secondary genetic and molecular events involved in the progression of these tumors are not well known. In this study, we have analyzed 45 MCLs (32 typical and 13 blastoid variants) by comparative genomic hybridization (CGH). To identify the possible genes included in the abnormal chromosome regions, selected cases were analyzed for P53, P16INK4a, RB, C-MYC, N-MYC, BCL2, BCL6, CDK4, and BMI-1 gene alterations. The most frequent imbalances detected by CGH were gains of chromosomes 3q (49%), 7p (27%), 8q (22%), 12q (20%), 18q (18%), and 9q34 (16%) and losses of chromosomes 13 (44%), 6q (27%), 1p (24%), 11q14-q23 (22%), 10p14-p15 (18%), 17p (16%), and 9p (16%). High-level DNA amplifications were identified in 11 different regions of the genome, predominantly in 3q27-q29 (13%), 18q23 (9%), and Xq28 (7%). The CGH analysis allowed the identification of regional consensus areas in most of the frequently involved chromosomes. Chromosome gains (P = .02) and losses (P = .01) and DNA amplifications (P = .015) were significantly higher in blastoid variants. The significant differences between blastoid and typical tumors were gains of 3q, 7p, and 12q, and losses of 17p. CGH losses of 17p correlated with P53 gene deletions and mutations. Similarly, gains of 12q and high-level DNA amplifications of 10p12-p13 were associated with CDK4 and BMI-1 gene amplifications, respectively. One of 2 cases with 8q24 amplification showed C-MYC amplification by Southern blot. Alterations in 2p, 3q, 13, and 18q were not associated with N-MYC, BCL6, RB, orBCL2 alterations, respectively, suggesting that other genes may be the targets of these genetic abnormalities in MCLs. Increased number of gains (0 v 1-4 v >4 gains per case) (P = .002), gains of 3q (P = .02), gains of 12q (P = .03), and losses of 9p (P = .003) were significantly associated with a shorter survival of the patients. These results indicate that an increased number of chromosome imbalances are associated with blastoid variants of MCLs and may have prognostic significance.

R248W Mutations in p53 Gene are Rare Among Indian Patients with Head-and-Neck Cancer

AbstractCancer is one of the curses to humankind, decades of research in eradicating the disease from the society is proven difficult. Close interaction between clinicians and scientists helps us to translate clinical observations into molecular mechanism of the disease. The Cancer Genome Atlas data suggest that genetic alterations in p53 gene play a crucial role in head-and-neck squamous cell carcinoma (HNSCC) tumorigenesis. Understanding p53 aberrations and their impact on other cellular activities can help with the design of new, more effective therapeutic strategy that target p53 mutation-bearing HNSCC, thereby producing a personalized medicine approach for the disease.In an effort to identify the role of R248W mutation of p53 gene in HNSCC patients of Indian origin, tumor samples were collected from 55 patients (n = 55), and polymerase chain reaction–restriction fragment length polymorphism technique was used to screen for the mutation using genomic DNA isolated from the tumors.The results reveal that except for one patient (heterozygous), all the patients were negative for the mutation.These results suggest that p53 R248W mutations are less prevalent in HNSCC Indian patients.

Identification of p53 gene alterations in canine mammary tumours using polymerase chain reaction and direct sequence analysis

Mammary tumours are mentioned as the most common tumours in female dogs and approximately half of them are detected malignant. p53 gene mutations are demonstrated to be the most common genetic alteration in canine mammary tumours. The present study was conducted to evaluate exon-1 of p53 gene mutations in tissue samples of canine mammary tumours by PCR and direct sequence analysis. After histopathological confirmation of the tissue sections by haematoxylin and eosin staining (10/26), deparaffinised samples were used for DNA extraction by silica gel method. Subsequently, p53 exon 1 was amplified through PCR assay using specific oligo nucleotide primers designed according to the canine DNA sequence available online. Microscopically, 10 out of 26 suspected tissue samples were recognised as malignant mammary gland tumours with various grades of malignancy. Surprisingly, one insertion of mutation was found in exon 1 of all examined samples corresponding to a sequence comprising 27 amino acids, between amino acids 30 to 57 in the p53 protein. Taken together, it seems that alteration of exon 1 p53 gene may lead to malignancy beha­viour, poor prognosis and short survival time in dogs with mammary carcinomas.

FGF10/FGFR2/ERK Signal Activation is Required for the Initiation, Maintenance and Progression of Intraductal Papillary Neoplasm of the Bile Duct

Evidence regarding intraductal papillary neoplasm of the bile duct (IPNB) as a new type of precancerous lesion of cholangiocarcinoma is limited. Moreover, a reproducible in vivo model is lacking and IPNB pathogenesis remains unclear. Here, we used a doxycycline-inducible Tet-on mice model facilitating the control of fibroblast growth factor 10 (FGF10) expression which contributes to branching and tubule formation. FGF10-induced IPNB mimicked the multifocal and divergent human IPNB phenotypes via the FGF10–FGFR2–RAS–ERK signalling pathway. A paracrine/autocrine growth factor was sufficient for the initiation and maintenance of IPNB originating from the peribiliary glands, including the biliary stem/progenitor cells. With KrasG12D, p53 and/or p16 gene alterations, Fgf10-induced IPNB showed stepwise carcinogenesis, causing associated invasive carcinoma. Fgf10-induced papillary changes were suppressed by FGF10–FGFR2–RAS–ERK signalling inhibition, which was inhibited with a MEK inhibitor, demonstrating that the signal is a novel therapeutic target for IPNB and associated carcinoma.

Mapping of TP53 protein network using Cytoscape software

TP53 acts as a tumor suppressor in cancer. It induces cell cycle arrest or apoptosis in response to cellularstress and damage. p53 gene alteration could cause uncontrolled cell proliferation. In the present study, weused TP53 gene as the seed in the construction of a protein-protein interaction network to identify genesthat might involve in tumorgenesis process with TP53. TP53 protein interaction database was obtainedfrom STRING version 9.1 program. High-throughput experimental data, literature data and hypotheticalstudies have been used to determine the roles of candidate genes in TP53 pathway. A total 500 genes fromSTRING database loaded into Cytoscape version 2.8.3. The 1762 protein interactions were assembled andvisualized in y organic form. We found eight specific non-overlapping clusters of various sizes, whichemerged from the huge network of protein-interactors using MCODE version 1.32 clustering algorithm.Biological Networks Gene Ontology (BiNGO) was used to determine two ontologies (molecular function andbiological process) involved in the protein network. Most of the genes mainly participated in gene andprotein expression, cell signaling and metabolism. A better understanding of the relationship between thegenes could aid in developing prognostic markers and better therapeutic strategies in cancer treatment.

Elevated expression of p53 in early colon polyps in a pig model of human familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is a hereditary predisposition to formation of colon polyps that can progress to colorectal cancer (CRC). The severity of polyposis varies substantially within families bearing the same germline mutation in the adenomatous polyposis coli (APC) tumour suppressor gene. The progressive step-wise accumulation of genetic events in tumour suppressor genes and oncogenes leads to oncogenic transformation, with driver alterations in the tumour protein p53 (TP53) gene playing a key role in advanced stage CRC. We analysed groups of pigs carrying a truncating mutation in APC (APC1311/+; orthologous to human APC1309/+) to study the influence of TP53 polymorphisms and expression on the frequency of polyp formation and polyp progression in early-stage FAP. Five generations of APC1311/+ pigs were examined by colonoscopy for polyposis severity and development. A total of 19 polymorphisms were found in 5′-flanking, coding, and 3′ untranslated regions of TP53. The distribution of TP53 genotypes did not differ between APC1311/+ pigs with low (LP) and high (HP) number of colon polyps. p53 mRNA expression was analysed in distally located normal mucosa samples of wild-type pigs, APC1311/+ LP and HP pigs, and also in distally located polyp samples histologically classified as low-grade (LG-IEN) and high-grade intraepithelial dysplastic (HG-IEN) from APC1311/+ pigs. p53 mRNA expression was found to be significantly elevated in HG-IEN compared to LG-IEN samples (p = 0.012), suggesting a role for p53 in the early precancerous stages of polyp development.

P16 Tumor Suppressor Gene Methylation in Diffuse Large B Cell Lymphoma: A Study of 88 Cases at Two Hospitals in the East Coast of Malaysia

Introduction:p16 gene plays an important role in the normal cell cycle regulation. Methylation of p16 has been reported to be one of the epigenetic events contributing to the pathogenesis of diffuse large B-cell lymphoma (DLBCL) which occurring at varying frequency. DLBCL is an aggressive and high-grade malignancy which accounts for approximately 30% of all non-Hodgkin lymphoma cases. However, little is known regarding the epigenetic alterations of p16 gene in DLBCL cases in Malaysia. Therefore, the objective of this study was to examine the status of p16 methylation in DLBCL.Methods:A total of 88 formalin-fixed paraffin-embedded DLBCL tissues retrieved from two hospitals located in the east coast of Malaysia, namely Hospital Tengku Ampuan Afzan (HTAA) Pahang and Hospital Universiti Sains Malaysia (HUSM) Kelantan, were chosen for this study. DNA specimens were isolated and subsequently subjected to bisulfite treatment prior to methylation specific-PCR. Two pairs of primers were used to amplify methylated and unmethylated regions of p16 gene. The PCR products were then separated using agarose gel electrophoresis and visualised under UV illumination. SPSS version 12.0 was utilised to perform all statistical analysis.Result:p16 methylation was detected in 65 of 88 (74%) samples. There was a significant association between p16 methylation status and patients aged >50 years old (p=0.04).Conclusion:Our study demonstrated that methylation of p16 tumor suppressor gene in our DLBCL cases is common and significantly increased among patients aged 50 years and above. Aging is known to be an important risk factor in the development of cancers and we speculate that this might be due to the increased transformation of malignant cells in aging cell population. However, this has yet to be confirmed with further research and correlate the findings with clinicopathological parameters.

P53: Multiple Facets of a Rubik's Cube.

The p53 tumor suppressor has been studied for decades, and still there are many questions left unanswered. In this review, we first describe the current understanding of the wild-type p53 functions that determine cell survival or death, and regulation of the protein, with a particular focus on the negative regulators, the murine double minute family of proteins. We also summarize tissue-, stress-, and age-specific p53 activities and the potential underlying mechanisms. Among all p53 gene alterations identified in human cancers, p53 missense mutations predominate, suggesting an inherent biological advantage. Numerous gain-of-function activities of mutant p53 in different model systems and contexts have been identified. The emerging theme is that mutant p53, which retains a potent transcriptional activation domain, also retains the ability to modify gene transcription, albeit indirectly. Lastly, because mutant p53 stability is necessary for its gain of function, we summarize the mechanisms through which mutant p53 is specifically stabilized. A deeper understanding of the multiple pathways that impinge upon wild-type and mutant p53 activities and how these, in turn, regulate cell behavior will help identify vulnerabilities and therapeutic opportunities.

THE EXON 5, 6, 7, 8 OF P53 MUTATIONS IN ORAL SQUAMOUS CELLS CARCINOMA

Genetic instability may underlie the etiology of multistep carcinogenesis. The altered p53 gene observed in tumors may represent the expression of such instability and may allow the accumulation of other gene alterations caused by multiple mechanism. p53 gene is the guardian of the genome, that is why we pay more attention to this gene. In this study, we evaluated the significance of p53 mutation in 55 patient with oral squamous carcinoma. Thirty among them underwent well-differentiated carcinoma, while the remaining 25 patientsunderwent poorly differentiated carcinoma. The mutations were detected by PCR-SSCP (Single strand Conformational Polymorphism) analysis in the region between exon 5 and exon 8. The results indicated that the p53 mutation in exon 5 (40%), exon 6 (28%), exon 7 (24%) and exon 8 (8%) were associated with poorly differentiated carcinoma, whereas mutation in exon 5 (10%), exon 6 (30%), exon 7 (40%) and exon 8 (20%) were associated with well-differentiated carcinoma. These observations suggest that p53 mutation in exon5, 6, and 7 have strong correlation with poorly differentiated in oral squamous carcinoma while well-differentiated level was related with mutation in exon 6,7 and 8.

Role of p53, Mitochondrial DNA Deletions, and Paternal Age in Autism: A Case-Control Study.

The tumor suppressor p53 responds to a variety of environmental stressors by regulating cell cycle arrest, apoptosis, senescence, DNA repair, bioenergetics and mitochondrial DNA (mtDNA) copy number maintenance. Developmental abnormalities have been reported in p53-deficient mice, and altered p53 and p53-associated pathways in autism (AU). Furthermore, via the Pten-p53 crosstalk, Pten haploinsufficient-mice have autisticlike behavior accompanied by brain mitochondrial dysfunction with accumulation of mtDNA deletions. mtDNA copy number and deletions, and p53 gene copy ratios were evaluated in peripheral blood monocytic cells from children aged 2-5 years with AU (n = 66), race-, gender-, and age-matched typically neurodeveloping children (n = 46), and both parents from each diagnostic group, recruited by the Childhood Autism Risk from Genes and Environment study at the University of California, Davis. mtDNA deletions and higher p53 gene copy ratios were more common in children with AU and their fathers. The incidence of mtDNA deletions in fathers of children with AU was increased 1.9-fold over fathers of typically neurodeveloping children, suggesting a role for deficient DNA repair capacity not driven by paternal age. Deletions in mtDNA and altered p53 gene copy ratios seem to result from genetics (children with severity scores ≥8) and/or act in concert with environmental factors (children with 6-7 severity scores). Given pro- and antioxidant activities of p53, and associations of genomic instability with disorders other than AU, our study suggests a link between DNA repair capacity, genomic instability in the 17p13.1 region influenced by environmental triggers, and AU diagnosis.

P16 Immuno-expression in oral squamous cell carcinomas.

Introduction: Head and neck squamous cell carcinoma is the 6th most common cancer worldwide. P16 gene is an important tumour suppressor gene cloned in chromosome 9p21. This gene encodes a protein that binds to inhibit cyclin-dependent kinase 4 (CDK4) and plays an important role in cell cycle regulation. The alteration of p16 gene is an important key for the early diagnosis of oral SCC and helps to evaluate tumour malignancy, aggression and prognosis.

Implication of K-ras and p53 in colorectal cancer carcinogenesis in Tunisian population cohort.

According to the multistep route of genetic alterations in the colorectal adenoma-carcinoma sequence, the complex K-ras/p53 mutation is one of the first alterations to occur and represent an important genetic event in colorectal cancer (CRC). An evaluation of the mutation spectra in K-ras and p53 gene was effected in 167 Tunisian patients with sporadic CRC to determine whether our populations have similar pattern of genetic alteration as in Maghrebin's population. Mutation patterns of codon 12-13 of K-ras and exon 5-8 of p53 were analyzed by immunohistochemistry and PCR-SSCP and confirmed by sequencing. Mutations in the K-ras gene were detected in 31.13 % and affect the women more than the men (p = 0.008). Immunostaining showed that expression of p21 ras was correlated with the advanced age (p = 0.004), whereas loss of signal was associated with mucinous histotype (p = 0.003). Kaplan-Meier survival curve found that patients with the K-ras mutation had a shorter survival compared with patients without mutation (p = 0.005). Alteration in p53 was seen in 17.4 % of patients and affects three hot spot codons such as 175, 245, and 248. Overexpression of p53 was seen in 34.1 % and correlated with tumor node metastasis (TNM) advanced stage (p = 0.037) and mucinous histotype (p = 0.001). A high concordance between p53 expression and alteration (p<0.005) was shown. Concomitant mutations in K-ras and p53 gene were detected in only 4 % of tumors. K-ras and p53 undergo separate pathways in colorectal tumorogenesis. Interestingly, mutations in the K-ras gene might be considered a valuable prognostic factor correlated to poor outcome. p53 gene alterations were rather low in our set, and methylation pattern of p53 is required to elucidate the molecular basis of this protein in CRC.

Clinicopathological and p53 Gene Alteration Comparison between Young and Older Patients with Gastric Cancer

Differences in clinicopathological characteristics of gastric cancer (GC) between young and older patients are controversial and a matter of debate. Determining the statistical significance of clinicopathological information with respect to age might provide clues for better management and treatment of GC. A total of 103 Indian GC patients were enrolled for study and specimens were classified according to the AJCC-TNM system. Patients were grouped into two age-wise categories, young patients (<40 years; n=13) and older patients (≥40 years, n=90). The clinicopathological features of both groups were retrospectively examined and compared. p53 alterations were analyzed by polymerase chain reaction-single strand conformational polymorphism and immunohistochemistry methods at gene and protein levels respectively. The cases were considered p53 over-expressed if it was present in more than 25% of the tumor cells and p53 alterations was correlated with the clinicopathological characteristics of the patients as well as etiological factors for GC in both groups. We found significant association of young patients with cancer stage (p=0.01), and very strong association with histology grade (p=0.064) and poorly differentiated (p=0.051) state of GC. However, neither young nor elderly patients showed associations with location, gender, etiological factors and p53 expression and alteration. Overall the male-to-female ratio of GC patients was 3.12 and the value was higher in the young (5.5) than in the older group (2.91). Clinicopathological features of GC like cancer stage, cell differentiation and histological grades were significantly different among young and old age cohorts. We observed a male predominance among the young group that decreased significantly with advancing age. More awareness of GC onset is required to detect cancer at an early stage for successful treatment.

Biomarkers and clonality before and after treatment

Adult T-cell leukemia-lymphoma (ATLL) is a disease with dismal prognosis urging new therapies. Few biomarkers have been identified to predict disease outcome in ATLL, however, routine testing for these is not widely available. The first line treatment option for ATLL can vary according to disease subtype, investigator’s choice, or institutional practices. For instance, experience at some centers suggest that there are patients with ATLL who can benefit from zidovudine (AZT)/interferon alpha (IFNα) therapy without requiring chemotherapy upfront. It has been reported that p53 gene alterations or MUM-/IRF-4 expression status may influence response to AZT/IFNα. More recently, the use of the anti-CD30 monoclonal antibody brentuximab vedotin is being advocated for the treatment of CD30+ T-cell malignancies, including ATLL. Therefore, establishing biomarkers that can help guide therapeutic decisions for ATLL would be ideal. Updated results and the usefulness of testing for some of these biomarkers will be discussed.