Current Cancer Drug Targets - Volume 9, Issue 4, 2009

The human HtrA family of serine proteases consists of four members: HtrA1, HtrA2, HtrA3 and HtrA4. Although prokaryotic HtrA proteins are well characterized in their dual roles as chaperones and proteases that degrade misfolded proteins in the periplasm, some members of mammalian HtrA proteins are described as potential modulators of programmed cell death and chemotherapy-induced cytotoxicity. Goal of this review article is to describe the molecular alterations associated with these HtrA serine proteases and how these alterations may be associated with tumor behavior and response to chemotherapy. We will also discuss evidence that chemotherapeutic drugs regulate the expression and activation of HtrA serine proteases and that these proteases contributes to programmed cell death. Finally, we will discuss the potential role of epigenetic therapy in targeting the expression and activation of HtrA serine proteases and the mechanisms by which these proteases enhance cytotoxic effect of conventional chemotherapy.

Psoralens (5-MOP and 8-MOP), a class of naturally occurring compounds, in combination with ultraviolect light are potent modulators of epidermal cell growth and differentiation. For a long time, photo-chemotherapy has been used in the treatment of psoriasis where it can reduce the number of cycling keratinocytes and decrease the IGF-1 receptors. However, the molecular mechanism of PUVA therapy remains unclear. In this study, we have evaluated, for the first time, in MCF-7 and SKBR-3 breast cancer cells the effects of 5-MOP (Bergapten), independently of its photoactivation, on the signalling pathways involved in cell cycle arrest and in apoptosis. Drug treatment induced a block in the G0/G1 phase and increased mRNA and protein levels of p53 and p21waf. These data correlate with a functional activation of caspase 8/caspase 9 together with DAPI staining and DNA ladder. Bergapten can transactivate p53 gene promoter in these cells and site-direct mutagenesis studies showed that the binding sequence of the nuclear factor NF-Y on p53 promoter is required for 5-MOP responsiveness. Besides, Bergapten increases NF-Y nuclear translocation through p38 MAPK activation. The same treatment impairs the PI3Kinase/AKT survival signal, in hormone-dependent MCF-7 cells even in the presence of IGF-I/E2 mitogenic factors. Here, we demonstrated that Bergapten, independently on the exposure to UV, generates membrane signalling pathways able to address apoptotic responses in breast cancer cells and to counteract the stimulatory effect of IGF-I/E2 on estrogenreceptor positive MCF-7 cell growth and progression.

Breast carcinogenesis is a multistep and multipath disease process which occurs in the epithelium lining of the ductal system in the vast majority of cases. Several studies have shown that the relative risk of breast cancer is increased in every step of this progression and many tumour associated antigens or biomarkers appear during each phase of carcinogenesis. However, their ability to predict for a substantial likelihood of developing breast cancer remains unclear. The acquisition of breast tissue samples, representative of an individual's cellular stability and subcellular biochemical and molecular state could lead to definition of surrogates for risk, early detection, pharmacodynamic determination and finally chemopreventive intervention. The intraductal approach includes nipple aspiration fluid (NAF), ductal lavage (DL) and mammary ductoscopy (MD). These techniques together with random periareolar fine needle aspiration (RPFNA) represent the available techniques for the sampling of breast fluid and exfoliated epithelial cells. At the moment, these procedures are not considered a screening procedure for early breast cancer detection but might provide a powerful research tool for studying breast carcinogenesis in vivo. We summarize the current knowledge regarding the vast array of molecules involved at all stages of carcinogenesis, which can be studied by intraductal approach, and the possibility to utilize them as candidate biomarkers to refine risk assessment, and their possible use in prevention strategies.

Arsenite exposure is associated with an increased risk of human lung cancer. However, the molecular mechanisms underlying the arsenite-induced human lung carcinogenesis remain elusive. In this study, we demonstrated that arsenite upregulates cyclin D1 expression/activity to promote the growth of human bronchial epithelial Beas-2B cells. In this process, the JNKs (c-Jun N-terminal kinases)/c-Jun cascade is elicited. The inhibition of JNKs or c-Jun by chemical or genetic inhibitors blocks the cyclin D1 induction mediated by arsenite. Furthermore, using a loss of function mutant of p85 (Δp85, a subunit of PI3K) or dominant-negative Akt (DN-Akt), we showed that PI3K and Akt act as the upstream regulators of JNKs and c-Jun in arsenite-mediated growth promotion. Overall, our data suggest a pathway of PI- 3K/Akt/JNK/c-Jun/cylin D1 signaling in response to arsenite in human bronchial epithelial cells.

By analyzing the cDNA obtained from 16 B-cell chronic lymphocytic leukemia (B-CLL) patient samples, we found that Nutlin-3, a small molecule inhibitor of MDM2/p53 interaction, induced a characteristic gene expression profile (GEP) signature in 13 out of 16 B-CLL samples. The lack of Nutlin-3-induced GEP signature in 3 out of 16 B-CLL samples was not due to p53 deletion and/or mutation, as demonstrated by FISH analysis and p53 sequencing. Of note, the 3 BCLL samples in which Nutlin-3 did not elicit the GEP signature were also less susceptible to Nutlin-3-mediated cytotoxicity with respect to the remaining 13 B-CLL samples. However, the partial lack of response in these p53 wild-type B-CLL samples was not due to defects in the ability of Nutlin-3 to promote p53 induction, as confirmed by the rapid accumulation of p53 protein at Western blot analysis in response to Nutlin-3 in all samples examined. Upon exposure to Nutlin-3, the genes up-regulated with the highest score in the majority of B-CLL cells were all known p53-target genes, including genes involved in apoptotic pathways, such as FAS and BAX, as well as MDM2. Taken together, our data indicate that the ability of Nutlin-3 to induce a characteristic GEP signature correlates with its cytotoxic potential in p53 wild-type BCLL cells. However, in some p53 wild-type B-CLL samples, the response to Nutlin-3 cannot be predicted on the basis of FISH analysis or p53 sequencing.

The integrin family of cell surface receptors integrates cell-extracellular matrix interactions with the cell cytoskeleton and signalling across the cell membrane, resulting in an important role in cell adhesion, mobility and migration, proliferation, and survival. Changes in the number and identity of integrin receptors are common in cancer cells resulting in alteration of the ability of malignant cells to interact with the extracellular matrix, and promoting migration as well as facilitating survival outside the tumour normal environment. β3 integrins are potentially involved in every step of the metastatic process and expression of both αρbβ3 and αvβ3 is correlated with metastatic ability of tumour cells. The recognition of the RGD binding motif common to the disintegrins and natural integrin ligands such as fibrinogen allowed the development of small molecule β3 integrin antagonists, progressing from linear peptides containing the RGD sequence to cyclic peptides with well-defined conformation, and hence to small molecule peptidomimetics with improved pharmacological properties. In this review, we summarize the role of the β3-subfamily of integrins when expressed in normal and tumour tissue, the development of small-molecule antagonists of β3 integrins and their potential anti-cancer applications.

Gynecologic Oncology has changed in the last few decades. An increasing proportion of patients is benefiting from long term survival although patients diagnosed with advanced disease suffer from a poor prognosis. Unfortunately, several recent studies are confirming that changing the combinations of “traditional” cytotoxic drugs is unlikely to obtain a real breakthrough in survival rates. Furthermore, there is discouraging data regarding consolidation therapies. It is, therefore, necessary to identify new target therapies with a minimal impact on quality of life. It is likely that new breakthroughs are only going to be achieved when changes in therapies are tailored to the entire natural history of the disease and on specific patient characteristic's. Since the discovery that tumor infiltrating lymphocytes represent an independent prognostic factor in ovarian cancer patients, several researchers have dedicated their attention to cancer immune response in order to identify prognostic factors and immunological targets. Analyses on immunophenotype at diagnosis and throughout the entire course of treatment are currently ongoing and are giving the new diagnostic, prognostic and therapeutic tools to the physicians. Furthermore new antigens and new vaccination strategies are being investigated. Encouraging data on selected patient populations have been observed recently. The objective of the present review is to define the immunology of women affected by gynecological malignancies and describe new immunological targets for prognostic and therapeutic use.

Nuclear factor-κB (NF-κB) is a key transcriptional factor family that consists of five members in mammalian cells, including NF-κB1 (p⁵⁰), NF-κB2 (p⁵²), RelA (p⁶⁵), RelB and c-Rel. NF-κB is implicated in multiple physiological and pathological processes, including cell proliferation and differentiation, inflammatory and immune response, cell survival and apoptosis, cellular stress reactions and tumorigenesis. Recent studies by our group and others have highlighted the novel functions of the p⁵⁰ protein. In this review, we will focus on the regulation and functions of NF-κB p⁵⁰.

Lung cancer is the leading cause of death from cancer in the world. Although the molecular network of lung carcinogenesis has been partly known at the levels of genes and proteins, and personalized therapy based on the genetic changes has made considerable progress in the last decade, the high mortality rate is not markedly changed. MicroRNAs (miRNAs), a class of short endogenous RNAs, acting as post-transcriptional regulators of gene expression, are similar with siRNAs in both the biosynthesis and the function steps. While, miRNAs mostly silence gene expression by binding imperfectly matched sequences in the 3' UTR of target mRNA, which is different with siRNAs by targeting ORF of mRNA with a perfectly complementary manner. miRNAs have multiple functions in lung development, and abnormal expression of miRNAs could lead to lung tumorigenesis. The different expression profiles of miRNAs in lung cancer, and the stability of miRNAs in serum, all together make them as new potentially clinical biomarkers for diagnosis and prognosis. Moreover, miRNAs may serve as either novel potential targets acting directly as oncogenes (e.g. miR-17-92 cluster) or directly therapeutic molecules working as tumor suppressor genes (e.g. let-7 family). RNAi technology based on miRNAs has many advantages over siRNAs, such as in vivo stability, highly RNA promoter-compatibility and no overt toxicity. Eventually, it might overcome the present disadvantages and become a good candidate for lung cancer therapy.