p53, known as a tumor suppressor, is a DNA binding protein that regulates cell cycle, activates DNA repair proteins, and triggers apoptosis in multicellular animals. More than 50% of human cancers contain a mutation or deletion of the p53 gene, and p53R175 is one of the hot spots of p53 mutation. Nucleic acid aptamers are short singlestranded oligonucleotides that are able to bind various targets, and they are typically isolated from an experimental procedure called systematic evolution of ligand exponential enrichment (SELEX). Using a previously unidentified strategy of contrast screening with SELEX, we have isolated an RNA aptamer targeting p53R175H. This RNA aptamer (p53R175H-APT) has a significantly stronger affinity to p53R175H than to the wild-type p53 in both in vitro and in vivo assays. p53R175H-APT decreased the growth rate, weakened the migration capability, and triggered apoptosis in human lung cancer cells harboring p53R175H. Further analysis actually indicated that p53R175H-APT might partially rescue or correct the p53R175H to function more like the wild-type p53. In situ injections of p53R175H-APT to the tumor xenografts confirmed the effects of this RNA aptamer on p53R175H mutation in mice.p53 | RNA aptamer | contrast screening | SELEX | tumor N ucleic acid aptamers, as single-stranded DNA or RNA oligonucleotides that are able to bind various targets with high specificity, were first isolated from a pool of random sequences with a process called systematic evolution of ligand exponential enrichment (SELEX) in 1990 by two laboratories (1, 2). Over the years, an array of methods have been invented to facilitate SELEX screening, and specific aptamers binding to partners ranging from small molecules to large proteins have been isolated. However, an RNA aptamer that can distinguish a protein with a single amino acid mutation from the wild-type (WT) protein remains absent (3-11).Protein with a single amino acid substitution is the cause of a plethora of human diseases (12)(13)(14). A well-known example is sickle-cell anemia, which is caused by a point mutation in the β-globin chain of hemoglobin (15). Also, point mutations in multiple tumor suppressor proteins cause cancer (16-18). The protein p53 is a tumor suppressor and functions as a transcription factor to regulate the expression of genes involved in DNA repair, cell cycle, and apoptosis. A mutation within one allele of this gene can result in inactivation of the remaining WT allele in a dominant-negative manner, and mutations from six mutation hot spots located in the DNA-binding surface of p53 are frequently found in almost all cancer types (19). Actually, more than half of human cancer cases relate to mutations in p53, and the single amino acid substitution p53R175H is one of the mutations at the p53R175 hot spot (20,21). R175H mutation abolishes the p53 WT functions in both MEF cells and thymocytes (22). p53R175H possesses a marked anti-apoptotic gain-of-function in lung cancer cells (23). Also, p53R175H cooperates better than any other mutant ...

An activating BRAF (V600E) kinase mutation occurs in approximately half of melanomas. Recent clinical studies have demonstrated that vemurafenib (PLX4032) and dabrafenib, potent and selective inhibitors of mutant v-raf murine sarcoma viral oncogene homolog B1 (BRAF), exhibit remarkable activities in patients with V600 BRAF mutant melanomas. However, acquired drug resistance invariably develops after the initial treatment. Identification of acquired resistance mechanisms may inform the development of new therapies that elicit long-term responses of melanomas to BRAF inhibitors. Here we report that increased expression of AEBP1 (adipocyte enhancer-binding protein 1) confers acquired resistance to BRAF inhibition in melanoma. AEBP1 is shown to be highly upregulated in PLX4032-resistant melanoma cells because of the hyperactivation of the PI3K/Akt-cAMP response element-binding protein (CREB) signaling pathway. This upregulates AEBP1 expression and thus leads to the activation of NF-κB via accelerating IκBa degradation. In addition, inhibition of the PI3K/Akt-CREB-AEBP1-NF-κB pathway greatly reverses the PLX4032-resistant phenotype of melanoma cells. Furthermore, increased expression of AEBP1 is validated in post-treatment tumors in patients with acquired resistance to BRAF inhibitor. Therefore, these results reveal a novel PI3K/Akt-CREB-AEBP1-NF-κB pathway whose activation contributes to acquired resistance to BRAF inhibition, and suggest that this pathway, particularly AEBP1, may represent a novel therapeutic target for treating BRAF inhibitor-resistant melanoma.

Background: hGH is an orthotopically expressed oncoprotein associated with mammary epithelial cell tumorigenesis. Results:The miR-96-182-183 cluster is regulated by autocrine/paracrine hGH and targets BRMS1L and GHR. Conclusion: Autocrine/paracrine hGH promotes breast cancer epithelial-mesenchymal transition and invasion via stimulating the miRNA-96-182-183 cluster. Significance: Autocrine/paracrine hGH and the miR-96-182-183 cluster might be exploited as a therapy or prognostic marker for breast cancer.

The death rates of hepatocellular carcinoma (HCC) are extremely high due to the paucity of therapeutic options. Animal models and anecdotal clinical evidence indicate a potential role of hGH and hPRL in HCC. However, the prognostic relevance and the functional role of tumor expression of these hormones in human HCC are not defined. Herein, we analyzed the mRNA and protein expression of hGH and hPRL in histopathological samples of non-neoplastic liver and HCC by in situ hybridization, PCR and immunohistochemistry techniques. Increased mRNA and protein expression of both hormones was observed in HCC compared with non-neoplastic liver tissues. hGH expression was significantly associated with tumor size and tumor grade. No significant association was observed between the expression of hPRL and any histopathological features. Amplification of both hGH and hPRL genes in HCC was observed when compared to non-neoplastic tissue. Expression of both hGH and hPRL was associated with worse relapse-free and overall survival in HCC patients. In vitro and in vivo functional assays performed with HCC cell lines demonstrated that autocrine expression of hGH or hPRL in HCC cells increased STAT3 activation, oncogenicity and tumor growth while functional antagonism with hGH-G120R significantly reduced these parameters. Hence, tumor expression of hGH/hPRL is associated with a worse survival outcome for patients with HCC and hGH/hPRL function as autocrine/paracrine promoters of HCC progression.