p53 Family in Resistance to Targeted Therapy of Melanoma

Metastatic melanoma is one of the most aggressive tumors, with frequent mutations affecting components of the MAPK pathway, mainly protein kinase BRAF. Despite promising initial response to BRAF inhibitors, melanoma progresses due to development of resistance. In addition to frequent reactivation of MAPK or activation of PI3K/AKT signaling pathways, recently, the p53 pathway has been shown to contribute to acquired resistance to targeted MAPK inhibitor therapy. Canonical tumor suppressor p53 is inactivated in melanoma by diverse mechanisms. The TP53 gene and two other family members, TP63 and TP73, encode numerous protein isoforms that exhibit diverse functions during tumorigenesis. The p53 family isoforms can be produced by usage of alternative promoters and/or splicing on the C- and N-terminus. Various p53 family isoforms are expressed in melanoma cell lines and tumor samples, and several of them have already shown to have specific functions in melanoma, affecting proliferation, survival, metastatic potential, invasion, migration, and response to therapy. Of special interest are p53 family isoforms with increased expression and direct involvement in acquired resistance to MAPK inhibitors in melanoma cells, implying that modulating their expression or targeting their functional pathways could be a potential therapeutic strategy to overcome resistance to MAPK inhibitors in melanoma.

Molecular profiles and urinary biomarkers of upper tract urothelial carcinomas associated with aristolochic acid exposure

Recurrent upper tract urothelial carcinomas (UTUCs) arise in the context of nephropathy linked to exposure to the herbal carcinogen aristolochic acid (AA). Here we delineated the molecular programs underlying UTUC tumorigenesis in patients from endemic aristolochic acid nephropathy (AAN) regions in Southern Europe. We applied an integrative multiomics analysis of UTUCs, corresponding unaffected tissues and of patient urines. Quantitative microRNA (miRNA) and messenger ribonucleic acid (mRNA) expression profiling, immunohistochemical analysis by tissue microarrays and exome and transcriptome sequencing were performed in UTUC and nontumor tissues. Urinary miRNAs of cases undergoing surgery were profiled before and after tumor resection. Ribonucleic acid (RNA) and protein levels were analyzed using appropriate statistical tests and trend assessment. Dedicated bioinformatic tools were used for analysis of pathways, mutational signatures and result visualization. The results delineate UTUC-specific miRNA:mRNA networks comprising 89 miRNAs associated with 1,862 target mRNAs, involving deregulation of cell cycle, deoxyribonucleic acid (DNA) damage response, DNA repair, bladder cancer, oncogenes, tumor suppressors, chromatin structure regulators and developmental signaling pathways. Key UTUC-specific transcripts were confirmed at the protein level. Exome and transcriptome sequencing of UTUCs revealed AA-specific mutational signature SBS22, with 68% to 76% AA-specific, deleterious mutations propagated at the transcript level, a possible basis for neoantigen formation and immunotherapy targeting. We next identified a signature of UTUC-specific miRNAs consistently more abundant in the patients' urine prior to tumor resection, thereby defining biomarkers of tumor presence. The complex gene regulation programs of AAN-associated UTUC tumors involve regulatory miRNAs prospectively applicable to noninvasive urine-based screening of AAN patients for cancer presence and recurrence.

Altered Expression of Shorter p53 Family Isoforms Can Impact Melanoma Aggressiveness

Cutaneous melanoma is the most aggressive form of skin cancer. Despite the significant advances in the management of melanoma in recent decades, it still represents a challenge for clinicians. The TP53 gene, the guardian of the genome, which is altered in more than 50% of human cancers, is rarely mutated in melanoma. More recently, researchers started to appreciate the importance of shorter p53 isoforms as potential modifiers of the p53-dependent responses. We analyzed the expression of p53 and p73 isoforms both at the RNA and protein level in a panel of melanoma-derived cell lines with different TP53 and BRAF status, in normal conditions or upon treatment with common anti-cancer DNA damaging agents or targeted therapy. Using lentiviral vectors, we also generated stable clones of H1299 p53 null cells over-expressing the less characterized isoforms Δ160p53α, Δ160p53β, and Δ160p53γ. Further, we obtained two melanoma-derived cell lines resistant to BRAF inhibitor vemurafenib. We observed that melanoma cell lines expressed a wide array of p53 and p73 isoforms, with Δ160p53α as the most variable one. We demonstrated for the first time that Δ160p53α, and to a lesser extent Δ160p53β, can be recruited on chromatin, and that Δ160p53γ can localize in perinuclear foci; moreover, all Δ160p53 isoforms can stimulate proliferation and in vitro migration. Lastly, vemurafenib-resistant melanoma cells showed an altered expression of p53 and p73 isoforms, namely an increased expression of potentially pro-oncogenic Δ40p53β and a decrease in tumor-suppressive TAp73β. We therefore propose that p53 family isoforms can play a role in melanoma cells' aggressiveness.

The Subcellular Localization and Oligomerization Preferences of NME1/NME2 upon Radiation-Induced DNA Damage

Nucleoside diphosphate kinases (NDPK/NME/Nm23) are enzymes composed of subunits NME1/NDPK A and NME2/NDPK B, responsible for the maintenance of the cellular (d)NTP pool and involved in other cellular processes, such as metastasis suppression and DNA damage repair. Although eukaryotic NDPKs are active only as hexamers, it is unclear whether other NME functions require the hexameric form, and how the isoenzyme composition varies in different cellular compartments. To examine the effect of DNA damage on intracellular localization of NME1 and NME2 and the composition of NME oligomers in the nucleus and the cytoplasm, we used live-cell imaging and the FRET/FLIM technique. We showed that exogenous NME1 and NME2 proteins co-localize in the cytoplasm of non-irradiated cells, and move simultaneously to the nucleus after gamma irradiation. The FRET/FLIM experiments imply that, after DNA damage, there is a slight shift in the homomer/heteromer balance between the nucleus and the cytoplasm. Collectively, our results indicate that, after irradiation, NME1 and NME2 engage in mutual functions in the nucleus, possibly performing specific functions in their homomeric states. Finally, we demonstrated that fluorophores fused to the N-termini of NME polypeptides produce the largest FRET effect and thus recommend this orientation for use in similar studies.

The role of p53 isoforms' expression and p53 mutation status in renal cell cancer prognosis

OBJECTIVES

To analyze p53 mutations and gene expression of p53, ∆40p53, and ∆133p53 isoforms in renal cell cancer (RCC) tissues and normal adjacent tissue (NAT) and to associate them to clinical features and outcome.

PATIENTS AND METHODS

Forty-one randomly selected patients, with primary, previously untreated RCC, with complete clinicopathohistological data were analyzed. NAT samples were available for 37 cases. Expression of p53, ∆40p53 and ∆133p53 was determined using RT-qPCR. A functional yeast-based assay was performed to analyze p53 mutations.

RESULTS

More than half (56.1%) of patients harbored functional p53 mutations, and they were significantly younger than those with wild type (WT) p53 (P = 0.032). Expression of p53, ∆40p53, and ∆133p53 was upregulated in mutant (MT) p53 RCC compared to WT p53 RCC tissues. However, there was no difference in expression of these isoforms between MT p53 RCC tissues and NAT. Expression of ∆133p53 was significantly downregulated in WT p53 tissues compared to NAT (P = 0.006). Patients that harbored functional p53 mutation had better overall survival (hazard ratio 4.32, 95% confidence interval 1.46-18.82, P = 0.006). Multivariate analysis demonstrated that tumor stage and p53 mutation might be used as independent prognostic marker for overall survival in RCC patients.

CONCLUSIONS

Our findings support the specific events in the carcinogenesis of RCC. p53 isoforms can be differentially expressed depending on p53 mutational status.

Expression profiles of p53/p73, NME and GLI families in metastatic melanoma tissue and cell lines

Unlike other tumours, TP53 is rarely mutated in melanoma; however, it fails to function as a tumour suppressor. We assume that its functions might be altered through interactions with several families of proteins, including p53/p73, NME and GLI. To elucidate the potential interplay among these families we analysed the expression profiles of aforementioned genes and proteins in a panel of melanoma cell lines, metastatic melanoma specimens and healthy corresponding tissue. Using qPCR a higher level of NME1 gene expression and lower levels of Δ40p53β, ΔNp73, GLI1, GLI2 and PTCH1 were observed in tumour samples compared to healthy tissue. Protein expression of Δ133p53α, Δ160p53α and ΔNp73α isoforms, NME1 and NME2, and N'ΔGLI1, GLI1FL, GLI2ΔN isoforms was elevated in tumour tissue, whereas ∆Np73β was downregulated. The results in melanoma cell lines, in general, support these findings. In addition, we correlated expression profiles with clinical features and outcome. Higher Δ133p53β and p53α mRNA and both GLI1 mRNA and GLI3R protein expression had a negative impact on the overall survival. Shorter overall survival was also connected with lower p53β and NME1 gene expression levels. In conclusion, all examined genes may have implications in melanoma development and functional inactivity of TP53.

Syntheses of gold nanoparticles and their impact on the cell cycle in breast cancer cells subjected to megavoltage X-ray irradiation

Gold nanoparticles (AuNPs) were synthesized in the presence of citrate (Au-CIT), glutathione (Au-GSH) and aminodextran (Au-DEX) in order to modify AuNPs surfaces and to increase their cellular uptake in the breast cancer cells MDA-MB-231. AuNPs were characterized with respect to their particle size, shape and colloidal stability in an aqueous solution and cell media. The mass accumulation of each AuNP type inside cancer cells was determined quantitatively, using Inductive Coupled Plasma - mass spectroscopy. The sub-cellular accumulation was studied using Transmission Electron Microscopy (TEM). It was found that gold nanoparticles applied to cancer cells were localized in cytoplasmic vesicles and that the highest uptake was shown in the presence of Au-GSH nanoparticles. The effect of AuNPs on the cell cycle was investigated using flow cytometry and Western blot analysis. The gold nanoparticles alone did not affect the cell cycle, as shown by flow cytometry. Furthermore, the cancer cells were irradiated using conventional clinically relevant high-energy X-ray radiation of 6 MV in the dose of 4 Gy. The results on cells only irradiated showed an S phase arrest six and 8 h after irradiation, and a G2/M arrest 24 and 48 h after irradiation. The irradiation of breast cancer cells treated with AuNPs has shown no significant variation in cell cycle distribution as opposed to X-ray radiation alone.

Mechanisms of fetal epigenetics that determine telomere dynamics and health span in adulthood

Advances in epigenetics now enable us to better understand environmental influences on the genetic background of human diseases. This refers especially to fetal development where an adverse intrauterine environment impacts oxygen and nutrient supply to the fetus. Recently, differences in telomere length and telomere loss dynamics among individuals born with intrauterine growth restriction compared to normal controls have been described. In this paper we propose possible molecular mechanisms that (pre)program telomere epigenetics during pregnancy. This programming sets differences in telomere lengths and dynamics of telomere shortening in adulthood and therefore dictates the dynamics of aging and morbidity in later life.

Suppression of Smad-1 mRNA expression level by Smad-2 likely control dichotomy of NF-κB and Smads mediated activation

The aim of this study was to find out how NF-κB and Smad-mediated signaling influenced the expression of astrogliogenic versus neurogenic markers of brain development in U4C cells which were either enriched (Tg Jak-1) or deprived in Jak-1 molecule (Jak-1 KO). Genetically modified U4C cells were transfected with NF-kB reporter plasmid in order to follow its activation when cells were cotransfected with different combinations of Smads constructs. In wild type cells no significant activation of NF-κB was observed while genetically modified cells exhibited somewhat different pattern of NF-κB activation depending on the Smad constructs combination used. The absence of NF-κB activation in Jak-1 transgenic cells transfected with Smad-1 plus Smad-3 was accompanied by the appearance of apoptotic cells as revealed by DAPI staining. Smad-1 expression was undetectable in Jak-1 transgenic cells and was downregulated in wild type cells upon transfection with Smad-2. The absence of p65 nuclear translocation in Smad-2 transfected cells and the presence of Smad-4 in nucleus of the same cells indicates dichotomy in NF-κB and Smads mediated signaling pathways. The significance of this study is that helps to elucidate the point of collaboration among three different signaling pathways - Jak-1 mediated cytokine signaling, NF-κB and Smads mediated pathways.

Differential effects of diverse p53 isoforms on TAp73 transcriptional activity and apoptosis

The p53 activities are due, at least in part, to its ability to form oligomers that bind to specific DNA sequences and activate transcription. Since some mutant p53 proteins and ΔNp73 isoforms form heterocomplexes with TAp73, we asked whether p53 isoforms can do the same and potentially act as dominant-negative inhibitors of TAp73. Moreover, it has already been found that some isoforms form complex with wtp53 and some of them inhibit p53 tumor-suppressor functions. Therefore, we studied the complex formation and co-immunoprecipitation assays show that all six p53 isoforms examined can form complexes with TAp73β, whereas only Δ133p53α/β/γ isoforms form complex with TAp73α. All p53 isoforms counteract TAp73β transactivation function but with different efficiency and in a promoter-dependent manner. Furthermore, apoptotic activity of TAp73β was augmented by coexpression of p53β, whereas Δ133p53α and β inhibit its apoptotic activity most efficiently. We have determined the half-life of different p53 isoforms: p53γ isoform has the shortest half-life, whereas Δ133p53γ has the longest half-life. Inhibitory interactions of two proteins in complex often lead to their stabilization. However, only three isoforms (Δ133p53α, Δ133p53β and Δ40p53α) stabilize TAp73β. We are convinced that defining the interactions between p53/p73 would give a new insight into how the p53 isoforms modulate the p73 functions in tumorigenesis.

Targeting p73--a potential approach in cancer treatment

The p53 family consists of three members: p53, p63 and p73. All three of them have a role in cell cycle arrest and induction of apoptosis. However, despite structural and partly functional similarity, there are striking differences in their functions and each of them has its own and unique identity. All three genes encode multiple variants with opposing functions in cancer development - full length transactivation forms with proapoptotic and antiproliferative functions, and dominant-negative transactivation-deficient forms with anti-apoptotic (oncogenic) functions. The functional interactions between family members are crucial to gain insight and understand their role in cancer biology. The discovery of p53/p73 network could have a major clinical impact in prognostic use and targeted drug design. In the current review we present the recent achievements in p73 research including very complex and sophisticated p73 regulation and response to DNA damage, and functional interactions among family members. We discuss how p73 has affected drug discovery. According to the p73 tumor suppressor function, we outline current aspects of anticancer therapy.

TP53 Mutational signature for aristolochic acid: an environmental carcinogen

This study was designed to establish the TP53 mutational spectrum of aristolochic acid (AA), examined in the context of endemic (Balkan) nephropathy, an environmental disease associated with transitional cell (urothelial) carcinomas of the upper urinary tract (UUC). Tumor tissue was obtained from residents of regions in Bosnia, Croatia and Serbia where endemic nephropathy has been prevalent for over 50 years. Fifty-nine TP53 mutations were detected in 42 of the 97 tumors analyzed. Mutational spectra were dominated by A:T to T:A transversions with the mutated adenines located almost exclusively on the nontranscribed strand. This marked strand bias is attributed to selective processing of aristolactam-dA adducts by transcription-coupled nucleotide excision repair. Hotspots for A:T to T:A mutations include codons 131 and 179 and the 5'-AG acceptor splice site of intron 6. The unique TP53 mutational signature for AA identified in this study can be used to explore the hypothesis that botanical products containing this human carcinogen and nephrotoxin are responsible, in part, for the high prevalence of UUC and chronic renal disease in countries where Aristolochia herbal remedies traditionally have been used for medicinal purposes.

Abstract LB-401: TP-53 mutational signature of a urothelial carcinogen

Aristolochic acid (AA), a powerful nephrotoxin and human carcinogen, was shown recently (PNAS, 102, 12129 (2007)) to be the causative agent in endemic (Balkan) nephropathy (EN). This devastating environmental disease is associated with a >50% incidence of urothelial carcinomas of the upper urinary tract (UUC). Following metabolic activation, AA reacts with genomic DNA to form covalent adducts (AL-DNA). These mutagenic lesions persist for decades in the renal cortex where they serve as robust biomarkers of exposure to AA. In EN, exposure occurs through ingestion of bread prepared from flour contaminated with AA. In China and other Asian countries, a significant fraction of the population also is exposed to AA, in this case through the medicinal use of herbal medicines prepared from Aristohchia plants. Such exposure, well-documented in Taiwan (JNCI, 102 1 (2009)) raises an important question: Do AA-induced cancers occur globally as a silent iatrogenic disease? To address this public health issue, we undertook a systematic study of 75 UUC patients residing in regions of Croatia, Bosnia and Serbia where EN and UUC are prevalent. DNA was obtained, with informed consent, from renal cortex and tumor tissues following nephroureterectomy. AL-DNA adducts were quantified by 32P- post-labeling techniques. Chip-sequencing technology was utilized to detect base substitutions in the TP-53 gene. Adducts were found in the renal cortex of 65% of patients with UUC. The TP53 mutation spectrum was dominated by A: TàT: A transversions located almost exclusively on the non-transcribed DNA strand. Twenty-five of these mutations occurred in exons and 12 mutations at 5′AG splice sites. Additionally, we identified several A: T àT: A mutational hotspots, including the first base of codon 131. TP53 gene mutations at this position have not previously been reported. The mechanism underlying the marked strand bias appears to be a selective failure to excise AL-DNA adducts by global genomic nucleotide excision repair. This factor also may account for the remarkable persistence of these adducts in human tissues, in some cases, for more than 50 years. Thus, AA joins vinyl chloride and aflatoxin as human chemical carcinogens with a definitive mutational signature. This information, coupled with the use of AL-DNA adducts as a biomarker, may be used to establish the role of AA ingestion in countries with a high prevalence of UUC and chronic renal disease. Importantly, public health authorities in countries where Aristolochia herbal preparations are in use should implement measures to reduce human exposure to this toxic and carcinogenic herb. (Supported by grant ES-04068 from NIEHS and the Croatian Ministry of Science)

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr LB-401.

Alternative splicing of p53 and p73: the novel p53 splice variant p53delta is an independent prognostic marker in ovarian cancer

Similar to p73, the tumor suppressor gene p53 is subject to alternative splicing. Besides p53DeltaE6 and p53beta, we identified p53zeta, p53delta and p53varepsilon, arising from alternative splicing of exon 6 and intron 9, respectively. p53 splice variants were present in 18 of 34 ovarian cancer cell lines (52.9%) and 134 of 245 primary ovarian cancers (54.7%). p53delta expression was associated with impaired response to primary platinum-based chemotherapy (P=0.032). Also, p53delta expression constituted an independent prognostic marker for recurrence-free and overall survival (hazard ratio 1.854, 95% confidence interval 1.121-3.065, P=0.016; and hazard ratio 1.937, 95% confidence interval 1.177-3.186, P=0.009, respectively). p53beta expression was associated with adverse clinicopathologic markers, that is, serous and poorly differentiated cancers (P=0.002 and P=0.008, respectively), and correlated with worse recurrence-free survival in patients exhibiting functionally active p53 (P=0.049). DeltaN'p73 constituted the main N-terminally truncated p73 isoform and was preferentially found in ovarian cancer cell lines showing functionally active p53, supporting our hypothesis that N-terminally truncated p73 isoforms can alleviate the selection pressure for p53 mutations by the inhibition of p53 protein function.

p53 mutations as fingerprints for aristolochic acid: an environmental carcinogen in endemic (Balkan) nephropathy

The activation of protooncogenes and inactivation of tumor suppressor genes are considered to be the main molecular events in the multistep process of carcinogenesis. Mutations of the TP53 tumor suppressor gene have been found in nearly all tumor types and are estimated to contribute to more than 50% of all cancers. Most mutations lead to the synthesis of highly stable, inactive proteins that accumulate in the nucleus of cancer cells. Among the 393 codons of the human p53 gene, 222 are targets of 698 different types of mutations. Alterations of codons 175, 248, 273 and 282 correspond to 19% of all mutations and are considered general hot spot mutations. Dietary exposure to aristolochic acid (AA), an established nephrotoxin and human carcinogen found in all Aristolochia species was shown to be the causative agent of aristolochic acid nephropathy (previously called Chinese herbs nephropathy). This syndrome is characterized by proximal tubular damage, renal interstitial fibrosis, slow progression to the end stage renal disease and a high prevalence of upper urinary tract urothelial carcinoma (otherwise a highly unusual location). AA preferentially binds to purines in DNA and is associated with a high frequency of A-->T transversions in the p53 gene. Rats treated with AA develop A:T-->T:A mutations in codon 61. The pathological and clinical features of endemic (Balkan) nephropathy closely resemble those associated with aristolochic acid nephropathy except for the slower progression to end stage renal disease and longer cumulative period before the appearance of urothelial cancer. Recently, we reported the presence of AA-DNA adducts in renal cortex and A-->T p53 mutations in tumor tissue of patients from Croatia and Bosnia with endemic nephropathy. These data support the hypothesis that dietary exposure to AA is a major risk factor for endemic (Balkan) nephropathy.

The effect of aprotinin on risk of acute renal failure requiring dialysis after on-pump cardiac surgery

The use of aprotinin in cardiac surgery to reduce perioperative bleeding and transfusion is controversial. We assessed the effect of aprotinin on the risk of acute renal failure in 423 patients who underwent on-pump cardiac surgery between January 1, 2005 and December 31, 2006. Of these 423 patients, 318 (75.2%) received aprotinin (median dose=3.0 million KIU, standard deviation=2.8 million KIU; interquartile range: 2 million KIU to 4 million KIU). Aprotinin was more likely to be used in patients who did not cease aspirin before surgery, in urgent or emergency surgery, who had impaired left ventricular function, a longer period of bypass and aortic cross-clamp time, and with both coronary artery bypass graft and valvular surgery performed. The overall incidence of acute renal failure requiring dialysis was 2.8%. The use of aprotinin was not associated with a reduction in transfusion nor an increased risk of renal failure requiring dialysis, atrial fibrillation, cerebrovascular accident or mortality in the univarate analyses. In the multivariate analysis, only preoperative serum creatinine concentration (odds ratio [OR] 1.06 per 10 micromol/l increment in creatinine, 95% confidence interval [CI]: 1.01 to 1.14, P=0.029) and urgency of the surgery (urgent vs. scheduled surgery: OR 12.8, CI: 2.3 to 70.8, P=0.004; emergency vs. scheduled surgery: OR 23.1, CI: 3.0 to 180.2, P=0.003) were significantly associated with an increased risk of acute renal failure requiring dialysis. The use of low-dose aprotinin did not significantly reduce perioperative transfusion requirements and was not a significant risk factor for acute renal failure requiring dialysis in our patients.

Aristolochic acid and the etiology of endemic (Balkan) nephropathy

Endemic (Balkan) nephropathy (EN), a devastating renal disease affecting men and women living in rural areas of Bosnia, Bulgaria, Croatia, Romania, and Serbia, is characterized by its insidious onset, invariable progression to chronic renal failure and a strong association with transitional cell (urothelial) carcinoma of the upper urinary tract. Significant epidemiologic features of EN include its focal occurrence in certain villages and a familial, but not inherited, pattern of disease. Our experiments test the hypothesis that chronic dietary poisoning by aristolochic acid is responsible for EN and its associated urothelial cancer. Using (32)P-postlabeling/PAGE and authentic standards, we identified dA-aristolactam (AL) and dG-AL DNA adducts in the renal cortex of patients with EN but not in patients with other chronic renal diseases. In addition, urothelial cancer tissue was obtained from residents of endemic villages with upper urinary tract malignancies. The AmpliChip p53 microarray was then used to sequence exons 2-11 of the p53 gene where we identified 19 base substitutions. Mutations at A:T pairs accounted for 89% of all p53 mutations, with 78% of these being A:T --> T:A transversions. Our experimental results, namely, that (i) DNA adducts derived from aristolochic acid (AA) are present in renal tissues of patients with documented EN, (ii) these adducts can be detected in transitional cell cancers, and (iii) A:T --> T:A transversions dominate the p53 mutational spectrum in the upper urinary tract malignancies found in this population lead to the conclusion that dietary exposure to AA is a significant risk factor for EN and its attendant transitional cell cancer.

Patterns of p73 N-terminal isoform expression and p53 status have prognostic value in gynecological cancers

The goal of this study was to determine whether patterns of expression profiles of p73 isoforms and of p53 mutational status are useful combinatorial biomarkers for predicting outcome in a gynecological cancer cohort. This is the first such study using matched tumor/normal tissue pairs from each patient. The median follow-up was over two years. The expression of all 5 N-terminal isoforms (TAp73, DeltaNp73, DeltaN'p73, Ex2p73 and Ex2/3p73) was measured by real-time RT-PCR and p53 status was analyzed by immunohistochemistry. TAp73, DeltaNp73 and DeltaN'p73 were significantly upregulated in tumors. Surprisingly, their range of overexpression was age-dependent, with the highest differences delta (tumor-normal) in the youngest age group. Correction of this age effect was important in further survival correlations. We used all 6 variables (five p73 isoform levels plus p53 status) as input into a principal component analysis with Varimax rotation (VrPCA) to filter out noise from non-disease related individual variability of p73 levels. Rationally selected and individually weighted principal components from each patient were then used to train a support vector machine (SVM) algorithm to predict clinical outcome. This SVM algorithm was able to predict correct outcome in 30 of the 35 patients. We use here a mathematical tool for pattern recognition that has been commonly used in e.g. microarray data mining and apply it for the first time in a prognostic model. We find that PCA/SVM is able to test a clinical hypothesis with robust statistics and show that p73 expression profiles and p53 status are useful prognostic biomarkers that differentiate patients with good vs. poor prognosis with gynecological cancers.

p63 and p73: roles in development and tumor formation

The tumor suppressor p53 is critically important in the cellular damage response and is the founding member of a family of proteins. All three genes regulate cell cycle and apoptosis after DNA damage. However, despite a remarkable structural and partly functional similarity among p53, p63, and p73, mouse knockout studies revealed an unexpected functional diversity among them. p63 and p73 knockouts exhibit severe developmental abnormalities but no increased cancer susceptibility, whereas this picture is reversed for p53 knockouts. Neither p63 nor p73 is the target of inactivating mutations in human cancers. Genomic organization is more complex in p63 and p73, largely the result of an alternative internal promoter generating NH2-terminally deleted dominant-negative proteins that engage in inhibitory circuits within the family. Deregulated dominant-negative p73 isoforms might play an active oncogenic role in some human cancers. Moreover, COOH-terminal extensions specific for p63 and p73 enable further unique protein-protein interactions with regulatory pathways involved in development, differentiation, proliferation, and damage response. Thus, p53 family proteins take on functions within a wide biological spectrum stretching from development (p63 and p73), DNA damage response via apoptosis and cell cycle arrest (p53, TAp63, and TAp73), chemosensitivity of tumors (p53 and TAp73), and immortalization and oncogenesis (DeltaNp73).

Transdominant DeltaTAp73 isoforms are frequently up-regulated in ovarian cancer. Evidence for their role as epigenetic p53 inhibitors in vivo

Despite strong homology, the roles of TP53 and TP73 in tumorigenesis seem to be fundamentally different. In contrast to TP53, tumor-associated overexpression of TP73 in many different cancers, combined with virtual absence of inactivating mutations and lack of a cancer phenotype in the TP73 null mouse are inconsistent with a suppressor function but instead support an oncogenic function. The discovery of NH(2)-terminally truncated p73 isoforms, collectively called DeltaTAp73, is now the focus of intense interest because they act as potent transdominant inihibitors of wild-type p53 and transactivation-competent TAp73. Therefore, establishing deregulated DeltaTAp73 expression in tumors could be the crucial link to decipher which of the two opposing roles of this bipolar gene is the biologically relevant one. This study is the largest to date and encompasses 100 ovarian carcinomas with complete expression profile of all NH(2)-terminal isoforms, discriminating between TAp73 and DeltaTAp73 (DeltaNp73, DeltaN'p73, Ex2p73, and Ex2/3p73) by isoform-specific real-time reverse transcription-PCR. We find that the set of NH(2)-terminal p73 isoforms distinguishes ovarian cancer patients from healthy controls and thus is a molecular marker for this diagnosis. Ovarian cancers strongly and almost universally overexpress DeltaN'p73 compared with normal tissues (95% of cancers). About one-third of tumors also exhibit concomitant up-regulation of the antagonistic TAp73, whereas only a small subgroup of tumors overexpress DeltaNp73. Thus, deregulation of the E2F1-responsive P1 promoter, rather than the alternate P2 promoter, is mainly responsible for the production of transdominant p53/TAp73 antagonists in ovarian cancer. Tumor stage, grade, presence of metastases, p53 status, and residual disease after resection are significant prognostic markers for overall and recurrence-free survival. A trend is found for better overall survival in patients with low expression of DeltaN'p73/DeltaNp73, compared with patients with high expression. A strong correlation between deregulated DeltaTAp73 and p53 status exists. p53 wild-type cancers exhibit significantly higher deregulation of DeltaN'p73, DeltaNp73, and Ex2/3p73 than p53 mutant cancers. This data strongly supports the hypothesis that overexpression of transdominant p73 isoforms can function as epigenetic inhibitors of p53 in vivo, thereby alleviating selection pressure for p53 mutations in tumors.

Mutational analysis of p53 in human tumors: immunocytochemistry

Mutations of the p53 gene are the most common genetic changes in human malignancies; therefore their detection is of practical importance. In contrast to wild-type p53 in resting normal cells, mutant p53 proteins are easily detectable by immunocytochemical methods due to their abnormally extended half-life. Several methods of immunocytochemistry can be used to analyze the presence and localization of p53 protein in cells or tissues. The most important is immunocytochemical p53 staining of sections from paraffin embedded tissues. This method is used as a relatively reliable surrogate marker for p53 mutations and has the advantage of being easy, fast, and suitable for mass screening of large archival tissue banks. Frozen sections can also be used to detect and localize the p53 proteins. p53 can also be detected in tissue culture cells. p53 can be detected in situ through a secondary antibody coupled to a fluorescent dye or an enzymatic activity that reacts with certain chromogens.

Mutational analysis of p53 in human tumors: direct DNA sequencing and SSCP

This chapter describes the techniques necessary to identify p53 genomic mutations in either frozen or paraffin-embedded tumor samples. DNA is extracted from the tumor samples and then used as a template to amplify the p53 coding sequences by polymerase chain reaction (PCR). The PCR products are characterized by agarose gel electrophoresis. Subsequently, mutations can be detected by direct DNA sequencing of the PCR products, followed by acrylamide gel electrophoresis and autoradiography. Alternatively, PCR products containing mutations can be identified by their aberrant mobility on denaturing acrylamide gels, using single-stranded conformation polymorphism (SSCP).

Novel Derivatives of Benzo[b]thieno[2,3-c]quinolones: Synthesis, Photochemical Synthesis, and Antitumor Evaluation

Novel derivatives of benzo[b]thieno[2,3-c]quinolones 3a-j were synthesized in a multistep synthesis starting from substituted benzo[b]thiophene-2-carbonyl chlorides, to their corresponding benzo[b]thiophene-2-carboxamides, which were photochemically dehydrohalogenated to their corresponding substituted benzo[b]thieno[2,3-c]quinolones. Compound 4 was prepared from 3i by alkylation with 3-dimethylaminopropyl chloride in the presence of NaH. Compounds 7a,b were prepared from 3g in the multistep synthesis from compounds 5 and 6. Compounds 3b, 3c-f, 3h, 7a, and 7b were found to exert cytostatic activity against malignant cell lines: pancreatic carcinoma (MiaPaCa2), breast carcinoma (MCF7), cervical carcinoma (HeLa), laryngeal carcinoma (Hep2), colon carcinoma (CaCo-2), melanoma (HBL), human fibroblast cell lines (WI-38). The compounds that bear a 3-dimethylaminopropyl substituent on the quinolone nitrogen (3b, 3c-f, 3h) showed higher antitumor activity than compounds bearing the same substituent on the amidic nitrogen (7a and 7b). The compound 3h, which has a 3-dimethylaminopropyl substituent on the quinolone nitrogen and a methoxycarbonyl substituent at position 9, had marked antitumor activity. Because of strong cytotoxic effect of compound 4 on melanoma cells (HBL, ME 67.3, and ME 67.1), a potential mechanism of action was examined. Analysis of DNA and Annexin-V-FLUOS staining indicated that compound 4 causes cell death by apoptosis.

Synthesis, structural studies, and biological evaluation of some purine substituted 1-aminocyclopropane-1-carboxylic acids and 1-amino-1-hydroxymethylcyclopropanes

The novel purine derivatives of 1-aminocyclopropane-1-carboxylic acid (8 and 9) and 1-amino-1-hydroxymethylcyclopropane (12 and 13) with methylene spacer between the base and the cyclopropane ring were prepared by multistep synthetic route involving alkylation of adenine and 6-(N-pyrrolyl)purine with 2-hydroxy-methyl-1-aminocyclopropane-1-carboxylic acid derivative 3 as a key reaction. All novel compounds were racemic. The N-9 substitution of the purine ring and the Z-configuration of the cyclopropane ring in 4-13 were deduced from their 1H and 13C NMR spectra by analyses of chemical shifts, H-H coupling constants and connectivities in two-dimensional homo- and heteronuclear correlation spectra. An unequivocal proof of the stereostructure of 1, 4 and 5 was obtained by their X-ray structure analysis. The novel compounds were evaluated on cytostatic and antiviral activities in several cell lines. The 6-(N-pyrrolyl)purine derivative of 1,2-aminocyclopropane alcohol 12 exhibited a more pronounced inhibitory activity against the proliferation of cervical carcinoma (HeLa) and human fibroblast (WI-38) cells than other types of tumor cell lines. None of the compounds showed inhibitory activities against cytomegalovirus, varicella-zoster virus or other viruses.

DeltaNp73, a dominant-negative inhibitor of wild-type p53 and TAp73, is up-regulated in human tumors

p73 has significant homology to p53. However, tumor-associated up-regulation of p73 and genetic data from human tumors and p73-deficient mice exclude a classical Knudson-type tumor suppressor role. We report that the human TP73 gene generates an NH(2) terminally truncated isoform. DeltaNp73 derives from an alternative promoter in intron 3 and lacks the transactivation domain of full-length TAp73. DeltaNp73 is frequently overexpressed in a variety of human cancers, but not in normal tissues. DeltaNp73 acts as a potent transdominant inhibitor of wild-type p53 and transactivation-competent TAp73. DeltaNp73 efficiently counteracts transactivation function, apoptosis, and growth suppression mediated by wild-type p53 and TAp73, and confers drug resistance to wild-type p53 harboring tumor cells. Conversely, down-regulation of endogenous DeltaNp73 levels by antisense methods alleviates its suppressive action and enhances p53- and TAp73-mediated apoptosis. DeltaNp73 is complexed with wild-type p53, as demonstrated by coimmunoprecipitation from cultured cells and primary tumors. Thus, DeltaNp73 mediates a novel inactivation mechanism of p53 and TAp73 via a dominant-negative family network. Deregulated expression of DeltaNp73 can bestow oncogenic activity upon the TP73 gene by functionally inactivating the suppressor action of p53 and TAp73. This trait might be selected for in human cancers.

Synthesis, photochemical synthesis and antitumor evaluation of novel derivatives of thieno[3',2':4,5]thieno[2,3-c]quinolones

The novel derivatives of thieno[3',2':4,5]thieno[2,3-c]quinolones 6a, 6b, 7, 10a and 10b were synthesized in multistep synthesis starting from thiophene-3-carboxaldehyde and malonic acid reacting in aldol condensation or from 3-bromothiophenes or methyl 4-bromothiophene-2-carboxylate reacting in Heck reaction. They resulted in corresponding substituted thienylacrylic acids 3a-c, which were cyclized into thieno[2,3-c]thiophene-2-carbonyl chlorides 4a-c and converted into thieno[2,3-c]thiophene-2-carboxamides 5a-d. Prepared carboxamides were photochemically dehydrohalogenated into corresponding substituted thieno[3',2':4,5]thieno[2,3-c]quinolones 6a-d. Compound 7 was prepared from 6d by alkylation with N-[3-(dimethylamino)propyl]chloride hydrochloride in the presence of NaH. Compounds 10a and 10b were prepared from 6c in the multistep synthesis over acid 8 and acid chloride 9. Compounds 6a, 6b, 7, 10a and 10b were found to exert cytostatic activities against malignant cell lines: pancreatic carcinoma (MiaPaCa2), breast carcinoma (MCF7), cervical carcinoma (HeLa), laryngeal carcinoma (Hep2), colon carcinoma (CaCo-2), melanoma (HBL), and human fibroblast cell lines (WI-38). The compound 6b, which bears the 3-dimethylaminopropyl substituent on quinolone nitrogen and methoxycarbonyl substituent on position 9, exhibited marked antitumor activity. On the contrary, compound 7, which also bears the 3-dimethylaminopropyl substituent on the quinolone nitrogen but anilido substituent on position 9, exhibited less antitumor activity than the others.

The efficacy of retroviral herpes simplex virus thymidine kinase gene transfer and ganciclovir treatment on the inhibition of melanoma growth in vitro and in vivo

One approach to gene therapy of cancer is based on the insertion of a suicide gene into tumor cells and subsequent activation of the suicide mechanism. We used the herpes simplex virus thymidine kinase (HSVtk) gene followed by ganciclovir (GCV) treatment. The goal of our experiments was to determine the effectiveness of HSVtk gene therapy in malignant melanoma. B16BL6 murine melanoma cells retrovirally transduced with the HSVtk gene became sensitive to low concentrations of GCV. Analysis by RT-PCR showed HSVtk expression in transduced B16BL6tk+ cells. Apoptotic cell death was found in B16BL6tk+ cells treated with GCV (20 microM). The sensitivity of B16BL6tk+ cells to GCV was also examined in vivo. Tumors inoculated subcutaneously into C57BL6 mice regressed rapidly when treated with GCV (50 mg/kg twice a day) and disappeared completely after 14 days treatment. The mice remained in remission for 5 months. A bystander effect through which nontransduced B16BL6 cells were also inhibited by GCV administration when cocultured with B16BL6tk+ cells was expected. However, only slight killing of nontransduced cells was observed in vitro. Analysis of the bystander effect in vivo showed complete regression of tumors inoculated with a mixture of cells mostly consisting of B16BL6tk+ cells. A distant bystander effect was also examined. There was no regression of wild-type tumors raised at a distant site from primary B16BL6tk+ tumors. The failure of a more effective bystander effect indicates the need for further investigation of the possible use of combined gene therapy to treat melanoma.

Expression of erbB-3 protein in colorectal adenocarcinoma: correlation with poor survival

BACKGROUND/AIMS

The family of erbB receptors includes four transmembrane glycoproteins with tyrosine kinase activity. These receptors are widely expressed in normal tissues, but they also have been implicated in the development of several human adenocarcinomas. c-erbB-3/HER-3 has been detected to a greater or lesser extent in many tissues from the digestive, urinary, reproductive and respiratory tracts. The overexpression of c-erbB-3/HER-3 protein has also been shown in 53%-88% of colorectal adenocarcinomas. In this study we investigated the expression of the c-erbB-3/ HER-3 gene product in colorectal tumour samples, and compared the results obtained with several clinicopathological parameters, including the survival of patients.

METHODS

Paraffin-embedded tissue sections were analysed immunohistochemically, using monoclonal antibody RTJ1 to human erbB-3 protein. Antibody RTJ1 specificity was confirmed by immunoprecipitation followed by Western blotting analysis. Amplification of the erbB-3 oncogene was tested by dot-blot hybridization.

RESULTS

Adenocarcinomas of the colon were positive for erbB-3 protein in 78% of samples examined. Dot-blot analysis showed no amplification of the erbB-3 gene in colon adenocarcinomas. Statistical analysis showed that patients with tumours that could not be stained for erbB-3 protein survived significantly longer (P<0.05) than patients with tumours staining positive for the erbB-3 protein. A Cox proportional-hazards model with stepwise variable selection identified age, sex and erbB-3 expression as important prognostic factors.

CONCLUSION

These findings demonstrate that erbB-3 protein expression could serve as a prognostic factor in colorectal malignancies.

Effect of extracellular NADH on human tumor cell proliferation

We investigated the antiproliferative effects of extracellular nicotinamide adenine dinucleotide against human malignant CaCo-2 (colon carcinoma), Hep-2 (laryngeal carcinoma), MCF-7 (breast carcinoma), CaSki (cervix carcinoma) cell lines, as well as against murine fibrosarcoma and normal human embryonal fibroblast (HEF). NADH was very potent in the growth inhibition of murine fibrosarcoma and human Hep-2 cells, regardless of the dose applied. During the observed period (4 or 5 days) only one dose of NADH was sufficient in reducing the growth rate for up to 92%. It had no effect on the growth of other cell lines tested. The identification of DNA-fragmentation and p53 and Ki-67 genes expression suggest that the mechanism of NADH action is different from disregulation of genes considered as check-points in cell cycle.

p185neu is expressed in yolk sac during rat postimplantation development

We have shown that the neu oncogene product (p185neu) is not present in the rat embryo before organogenesis. However, coincident with the onset of organogenesis, p185neu was detected in neural and connective tissue as well as in the secretory epithelium as was described by Kokai et al. (1987). In addition, p185neu is also expressed in the rat visceral yolk sac (VYS) endodermal cells but not in the mesenchymal and mesothelial layers of the same structure nor in the amnion. The first detectable sign of p185neu expression in VYS was found at d 11 of gestation and the levels of protein increased towards the end of pregnancy. In the yolk sac carcinoma (YSC), which is considered to be the malignant counterpart of the rat yolk sac, p185neu was observed only within columnar epithelial cells (the visceral component of the neoplasm) while parietal endoderm-like cells were devoid of detectable protein. From d 9 of pregnancy up to delivery some of the trophoblastic giant cells also showed a faint to moderate immunoreactivity. Results are presented which would indicate a possible role of p185neu in rat embryogenesis.

Collagenase derived from human fibrosarcoma is responsible for degradation of basement membranes

A collagenase-like enzyme with the ability to degrade the proteins of artificial basement membranes (BM) was isolated from human fibrosarcoma. Secretion of the same peptide was observed from the primary fibrosarcoma cell cultures. This peptide degrades the artificial basement membranes derived from bovine corneal endothelial cells. Using electrophoretic methods it was found that the isolated and partially purified enzyme consists of eight bands of different molecular mass corresponding to the collagenase standard from Cl. histolyticum. Only two bands with molecular masses of 22,000 (pI 5.5) and 63,000 (pI 5.9) degrade BM.

Localized amyloid of the ureter--case report and review of the literature

An unusual case of localized amyloidosis of the ureter is described and a review of the 12 previously reported cases is presented. No case had been diagnosed prior to surgery. Loin pain, with or without haematuria, associated with a sterile pyuria and an abnormal pyelogram were the commonest clinical signs. In the case reported an incidental small renal cell carcinoma was also present and the association of amyloidosis and neoplasia is discussed.

Arterial embolisation in renal carcinoma: a useful procedure?

Twenty-eight patients underwent embolisation over a 2-year period. III effects followed embolisation in 16 (57%), 2 of whom died. Attention is drawn to the intolerance of many patients to the length of the procedure. Of 24 patients undergoing operation, one case was inoperable and difficulty was encountered in 9. No perirenal plane of oedema was identified. No specimen examined histologically showed complete infarction. The tumour tissue was more resistant to infarction than normal kidney and 8 tumours (35%) appeared to have escaped completely. It is concluded that the role of embolisation is limited and that a combination of methods for achieving adequate arterial occlusion must be used for the optimum effect.