Cross-species comparison of orthologous gene expression in human bladder cancer and carcinogen-induced rodent models

Genes differentially expressed by tumor cells represent promising drug targets for anti-cancer therapy. Such candidate genes need to be validated in appropriate animal models. This study examined the suitability of rodent models of bladder cancer in B6D2F1 mice and Fischer-344 rats to model clinical bladder cancer specimens in humans. Using a global gene expression approach cross-species analysis showed that 13-34% of total genes in the genome were differentially expressed between tumor and normal tissues in each of five datasets from humans, rats, and mice. About 20% of these differentially expressed genes overlapped among species, corresponding to 2.6 to 4.8% of total genes in the genome. Several genes were consistently dysregulated in bladder tumors in both humans and rodents. Notably, CNN1, MYL9, PDLIM3, ITIH5, MYH11, PCP4 and FM05 were found to commonly down-regulated; while T0P2A, CCNB2, KIF20A and RRM2 were up-regulated. These genes are likely to have conserved functions contributing to bladder carcinogenesis. Gene set enrichment analysis detected a number of molecular pathways commonly activated in both humans and rodent bladder cancer. These pathways affect the cell cycle, HIF-1 and MYC expression, and regulation of apoptosis. We also compared expression changes at mRNA and protein levels in the rat model and identified several genes/proteins exhibiting concordant changes in bladder tumors, including ANXA1, ANXA2, CA2, KRT14, LDHA, LGALS4, SERPINA1, KRT18 and LDHB. In general, rodent models of bladder cancer represent the clinical disease to an extent that will allow successful mining of target genes and permit studies on the molecular mechanisms of bladder carcinogenesis

Gene expression in extratumoral microenvironment predicts clinical outcome in breast cancer patients

Abstract Introduction A gene expression signature indicative of activated wound responses is common to more than 90% of non-neoplastic tissues adjacent to breast cancer, but these tissues also exhibit substantial heterogeneity. We hypothesized that gene expression subtypes of breast cancer microenvironment can be defined and that these microenvironment subtypes have clinical relevance. Methods Gene expression was evaluated in 72 patient-derived breast tissue samples adjacent to invasive breast cancer or ductal carcinoma in situ. Unsupervised clustering identified two distinct gene expression subgroups that differed in expression of genes involved in activation of fibrosis, cellular movement, cell adhesion and cell-cell contact. We evaluated the prognostic relevance of extratumoral subtype (comparing the Active group, defined by high expression of fibrosis and cellular movement genes, to the Inactive group, defined by high expression of claudins and other cellular adhesion and cell-cell contact genes) using clinical data. To establish the biological characteristics of these subtypes, gene expression profiles were compared against published and novel tumor and tumor stroma-derived signatures (Twist-related protein 1 (TWIST1) overexpression, transforming growth factor beta (TGF-β)-induced fibroblast activation, breast fibrosis, claudin-low tumor subtype and estrogen response). Histological and immunohistochemical analyses of tissues representing each microenvironment subtype were performed to evaluate protein expression and compositional differences between microenvironment subtypes. Results Extratumoral Active versus Inactive subtypes were not significantly associated with overall survival among all patients (hazard ratio (HR) = 1.4, 95% CI 0.6 to 2.8, P = 0.337), but there was a strong association with overall survival among estrogen receptor (ER) positive patients (HR = 2.5, 95% CI 0.9 to 6.7, P = 0.062) and hormone-treated patients (HR = 2.6, 95% CI 1.0 to 7.0, P = 0.045). The Active subtype of breast microenvironment is correlated with TWIST-overexpression signatures and shares features of claudin-low breast cancers. The Active subtype was also associated with expression of TGF-β induced fibroblast activation signatures, but there was no significant association between Active/Inactive microenvironment and desmoid type fibrosis or estrogen response gene expression signatures. Consistent with the RNA expression profiles, Active cancer-adjacent tissues exhibited higher density of TWIST nuclear staining, predominantly in epithelium, and no evidence of increased fibrosis. Conclusions These results document the presence of two distinct subtypes of microenvironment, with Active versus Inactive cancer-adjacent extratumoral microenvironment influencing the aggressiveness and outcome of ER-positive human breast cancers

Dehydroepiandrosterone inhibits the progression phase of mammary carcinogenesis by inducing cellular senescence via a p16-dependent but p53-independent mechanism

INTRODUCTION: Dehydroepiandrosterone (DHEA), an adrenal 17-ketosteroid, is a precursor of testosterone and 17β-estradiol. Studies have shown that DHEA inhibits carcinogenesis in mammary gland and prostate as well as other organs, a process that is not hormone dependent. Little is known about the molecular mechanisms of DHEA-mediated inhibition of the neoplastic process. Here we examine whether DHEA and its analog DHEA 8354 can suppress the progression of hyperplastic and premalignant (carcinoma in situ) lesions in mammary gland toward malignant tumors and the cellular mechanisms involved. METHODS: Rats were treated with N-nitroso-N-methylurea and allowed to develop mammary hyperplastic and premalignant lesions with a maximum frequency 6 weeks after carcinogen administration. The animals were then given DHEA or DHEA 8354 in the diet at 125 or 1,000 mg/kg diet for 6 weeks. The effect of these agents on induction of apoptosis, senescence, cell proliferation, tumor burden and various effectors of cellular signaling were determined. RESULTS: Both agents induced a dose-dependent decrease in tumor multiplicity and in tumor burden. In addition they induced a senescent phenotype in tumor cells, inhibited cell proliferation and increased the number of apoptotic cells. The DHEA-induced cellular effects were associated with increased expression of p16 and p21, but not p53 expression, implicating a p53-independent mechanism in their action. CONCLUSION: We provide evidence that DHEA and DHEA 8354 can suppress mammary carcinogenesis by altering various cellular functions, inducing cellular senescence, in tumor cells with the potential involvement of p16 and p21 in mediating these effects

Differential Gene Expression in Chemically Induced Mouse Lung Adenomas

Because of similarities in histopathology and tumor progression stages between mouse and human lung adenocarcinomas, the mouse lung tumor model with lung adenomas as the endpoint has been used extensively to evaluate the efficacy of putative lung cancer chemopreventive agents. In this study, a competitive cDNA library screening (CCLS) was employed to determine changes in the expression of mRNA in chemically induced lung adenomas compared with paired normal lung tissues. A total of 2555 clones having altered expression in tumors were observed following competitive hybridization between normal lung and lung adenomas after primary screening of over 160,000 clones from a mouse lung cDNA library. Among the 755 clones confirmed by dot blot hybridization, 240 clones were underexpressed, whereas 515 clones were overexpressed in tumors. Sixty-five clones with the most frequently altered expression in six individual tumors were confirmed by semiquantitative RT-PCR. When examining the 58 known genes, 39 clones had increased expression and 19 had decreased expression, whereas the 7 novel genes showed overexpression. A high percentage (>60%) of overexpressed or underexpressed genes was observed in at least two or three of the lesions. Reproducibly overexpressed genes included ERK-1, JAK-1, surfactant proteins A, B, and C, NFAT1, α-1 protease inhibitor, helix-loop-helix ubiquitous kinase (CHUK), α-adaptin, α-1 PI2, thioether S-methyltransferase, and CYP2C40. Reproducibly underexpressed genes included paroxanase, ALDH II, CC10, von Ebner salivary gland protein, and α- and β-globin. In addition, CCLS identified several novel genes or genes not previously associated with lung carcinogenesis, including a hypothetical protein (FLJ11240) and a guanine nucleotide exchange factor homologue. This study shows the efficacy of this methodology for identifying genes with altered expression. These genes may prove to be helpful in our understanding of the genetic basis of lung carcinogenesis and in developing biomarkers for lung cancer chemoprevention studies in mice

Efficacy of Deguelin and Silibinin on Benzo(a)pyrene-Induced Lung Tumorigenesis in A/J Mice

We evaluated deguelin and silibinin in A/J mice treated with the tobacco-specific carcinogen benzo(a)pyrene (BP) for their ability to inhibit pulmonary adenoma formation and growth. Animals were treated with either deguelin (5.0 or 10.0 mg/kg body weight, by gavage) or silibinin at doses of 0.05% and 0.1% in the diet, approximately 10 days before a single intraperitoneal dose of BP. We found that oral administration of deguelin reduced tumor multiplicity by 56% and tumor load by 78%, whereas silibinin treatment at doses of 0.05% and 0.1% in the diet did not show any significant efficacy on either tumor multiplicity or tumor load. The result indicates that deguelin significantly inhibits pulmonary adenoma formation and growth in A/J mice. Finding new and effective agents that can prevent lung cancer is urgently needed because cancer of the lungs remains the principal cause of cancer deaths in the United States and because effective chemoprevention of this cancer type remains elusive. Thus, deguelin appears to be a promising new preventive agent for lung cancer and may be considered for further studies in other animal models and in clinical trials