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Lineage plasticity, the ability of a cell to alter its identity, is an increasingly common mechanism of adaptive resistance to targeted therapy in cancer. An archetypal example is the development of neuroendocrine prostate cancer (NEPC) after treatment of prostate adenocarcinoma (PRAD) with inhibitors of androgen signaling. NEPC is an aggressive variant of prostate cancer that aberrantly expresses genes characteristic of neuroendocrine (NE) tissues and no longer depends on androgens. Here, we investigate the epigenomic basis of this resistance mechanism by profiling histone modifications in NEPC and PRAD patient-derived xenografts (PDXs) using chromatin immunoprecipitation and sequencing (ChIP-seq). We identify a vast network of cis-regulatory elements (N~15,000) that are recurrently activated in NEPC. The FOXA1 transcription factor (TF), which pioneers androgen receptor (AR) chromatin binding in the prostate epithelium, is reprogrammed to NE-specific regulatory elements in NEPC. Despite loss of dependence upon AR, NEPC maintains FOXA1 expression and requires FOXA1 for proliferation and expression of NE lineage-defining genes. Ectopic expression of the NE lineage TFs ASCL1 and NKX2-1 in PRAD cells reprograms FOXA1 to bind to NE regulatory elements and induces enhancer activity as evidenced by histone modifications at these sites. Our data establish the importance of FOXA1 in NEPC and provide a principled approach to identifying cancer dependencies through epigenomic profiling.

Purpose: Management of locally advanced rectal cancer (RC) consists of neoadjuvant chemoradiotherapy (CRT) with fluoropyrimidines, followed by total mesorectal excision. We sought to evaluate the expression of selected genes, some of which were derived from a previous undirected SAGE (serial analysis of gene expression)-based approach, before and after CRT, to identify mechanisms of resistance., Methods: This retrospective cohort study included 129 consecutive patients. Quantitative polymerase chain reaction of 53 candidate genes was performed on the biopsy specimen before treatment and on the surgical specimen after CRT. A paired-samples t test was performed to determine genes that were significantly changed after CRT. The result was correlated with patients' disease-free survival., Results: Twenty-two genes were significantly upregulated, and two were significantly downregulated. Several of the upregulated genes have roles in cell cycle control; these include CCNB1IP1, RCC1, EEF2, CDKN1, TFF3, and BCL2. The upregulation of TFF3 was associated with worse disease-free survival on multivariate analyses (hazard ratio, 2.64; P=.027). Patients whose surgical specimens immunohistochemically showed secretion of TFF3 into the lumen of the tumoral microglands had a higher risk of relapse (hazard ratio, 2.51; P=.014). In vitro experiments showed that DLD-1 cells stably transfected with TFF3 were significantly less sensitive to 5-fluorouracil and showed upregulation of genes involved in the transcriptional machinery and in resistance to apoptosis., Conclusion: Upregulation of TFF3 after CRT for RC is associated with a higher risk of relapse. The physiological role of TFF3 in restoring the mucosa during CRT could be interfering with treatment efficacy. Our results could reveal not only a novel RC prognostic marker but also a therapeutic target., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Introduction: TNM and histological subtype are the most important prognostic criteria in gastric cancer. In this study, we have tried to identify an immunohistochemical protein profile involved in gastric recurrence after a radical surgery., Materials and Methods: In this paper, protein panels involved in gastric carcinogenesis and progression was analyzed by immunohistochemistry expression: p53, Ki-67, Bcl-2, COX-2, c-erb-B2, EPO-R, E-cadherin, and β-catenin in 44 gastrectomy samples coming from gastrectomy pieces of patients diagnosed and operated on adenocarcinoma of the stomach followed by adjuvant treatment based on MacDonald chemoradiation regimen. An immunostaining profile that could predict the relapse after the end of adjuvant treatment was tried to find. These results have shown that the expression of the adverse prognostic protein profile based on positive p53 immunohistochemical expression and non-conserved E-cadherin/B-catenin staining is associated with tumor recurrence and a poor disease-free survival in operated gastric cancer patients with curative intent followed by adjuvant chemoradiation according to MacDonald's regimen. A protein profile based on immunohistochemical expression of p53 and E-cadherin-B-catenin that has a significant correlation to disease-free survival was identified in gastric cancer samples.

The primary aim was to determine whether Epo-R immunohistochemical expression is related to disease free survival (DFS) in specimens of GC from patients who underwent adjuvant chemoradiation. Specimens of gastric adenocarcinomas obtained from 44 patients who had undergone curative gastrectomy and adjuvant treatment were investigated immunohistochemically expression of Epo-R. Three patterns for Epo-R staining were defined: Pattern A (secretory cells-like staining), Pattern B (parietal-like staining) and Pattern C (chief-like staining). Median DFS was 38 months (CI 95%: 33-43) and 15 months (IC 95%: 3-27) in the pattern B and C, respectively, but it was not reached in the pattern A (p = 0.06). Our findings suggest that there may be a relationship between Epo-R expression and DFS in the patients with GC resected.

Cdc42, a member of Rho GTPases family, is involved in the regulation of several cellular functions, such as rearrangement of actin cytoskeleton, membrane trafficking, cell-cycle progression, and transcriptional regulation. Aberrant expression or activity of Cdc42 has been reported in several tumours. Here, the specific role of Cdc42 in development and progression of colorectal cancer was analyzed through microarrays technology. A comparative analysis of Cdc42 overexpressing cells versus cells with decreased Cdc42 levels through siRNA revealed that Cdc42 overexpression down-regulated the potential tumour suppressor gene ID4. Results were validated by quantitative RT-PCR and the methylation status of the specific promoter, analyzed. Methylation-specific PCR and bisulfite sequencing PCR analysis revealed that Cdc42 induced the methylation of the CpG island of the ID4 promoter. Colorectal adenocarcinoma samples were compared with the corresponding adjacent normal tissue of the same patient in order to determine specific gene expression levels. The downregulation of ID4 by Cdc42 was also found of relevance in colorectal adenocarcinoma biopsies. Cdc42 was found to be overexpressed with high incidence (60%) in colorectal cancer samples, and this expression was associated with silencing of ID4 with statistical significance (p<0.05). Cdc42 may have a role in the development of colon cancer. Furthermore, inhibition of Cdc42 activity may have a direct impact in the management of colorectal cancer.

Colorectal adenocarcinoma is the second cause of cancer mortality in developed countries. Rac1 is a member of the family of Rho GTPases that regulates many intracellular signaling pathways, including those involved in tumorigenesis, invasion, and metastasis. We have investigated the role of Rac1 in colorectal tumor progression by genetic modification of the human colorectal adenocarcinoma cell line SW620 to either overexpress Rac1 or lack Rac1 expression. Tumor behavior was studied by orthotopic injection of stably modified cell lines into the cecal wall of athymic nude mice, a model that replicates the histopathological appearance and clinical behavior of human colorectal adenocarcinoma in humans. While overexpression of Rac1 resulted in an accelerated tumorigenic process, inducing a faster mortality rate, inhibition of Rac1 completely suppressed tumor formation. These results suggest that Rac1 plays a major role in colorectal adenocarcinoma progression. Finally, interference with Rac1 function may provide an important tool to block the malignant phenotype of colorectal adenocarcinoma cells.

Scarce data are available regarding the molecular mechanisms implicated in paclitaxel resistance. There is controversial data about beta-tubulin mutations role in paclitaxel resistance. We have conducted this trial to address the influence of beta-tubulin mutations in paclitaxel resistance in advanced non-small cell lung cancer (NSCLC). A group of 15 patients were biopsied and diagnosed of stages IIIB and IV NSCLC. Tumor specimens were used for DNA isolation and exon 4 of HM40 beta-tubulin isotype was amplified and automatically sequenced, using both intronic and exonic primers. Next, the chemotherapy schedule consisted of weekly paclitaxel (100 or 150 mg/m(2) x 6) followed 2 weeks later by cisplatin 100 mg/m(2) on day 1, gemcitabine 1000 mg/m(2) on days 1 and 14, and vinorelbine 25 mg/m(2) on days 1 and 14, every 28 days. Using exonic primers, gene sequence alterations were found in 13/15 (87%) patients, including transitions (codons 180 and 182) and one silent transversion (codon 195). Also, three transversions (codons 231, 234, and 235) were found in all patients and controls. All alterations disappeared when sequenced with intronic primers. Our results suggest that point mutations demonstrated with exonic primers but not with intronic ones are probably due to beta-tubulin pseudogenes present in advanced NSCLC specimens. Even so, when these beta-tubulin pseudogenes are found there is a clear relation with clinical response. Although these changes could be relevant in paclitaxel resistance, this observation must be proven in future clinical trials to resolve "the tubulin dilemma".