Anti-Cancer Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry - Anti-Cancer Agents) - Volume 14, Issue 3, 2014

β2-microglobulin (β2-m) has become the focus of intense scrutiny since the discovery of its undesirable roles promoting osteomimicry and cancer progression. β2-m is a well-known housekeeping protein that forms complexes with the heavy chain of major histocompatibility complex class I molecules, which are heterodimeric cell surface proteins that present antigenic peptides to cytotoxic T cells. On recognition of foreign peptide antigens on cell surfaces, T cells actively bind and lyse antigen-presenting cancer cells. In addition to its roles in tumor immunity, β2-m has two different functions in cancer cells, either tumor promoting or tumor suppressing, in cancer cell context-dependent manner. Our studies have demonstrated that β2-m is involved extensively in the functional regulation of growth, survival, apoptosis, and even metastasis of cancer cells. We found that β2-m is a soluble growth factor and a pleiotropic signaling molecule which interacts with its receptor, hemochromatosis protein, to modulate epithelial-to-mesenchymal transition (EMT) through iron-responsive pathways. Specific antibodies against β2-m have remarkable tumoricidal activity in cancer, through β2-m action on iron flux, alterations of intracellular reactive oxygen species, DNA damage and repair enzyme activities, β-catenin activation and cadherin switching, and tumor responsiveness to hypoxia. These novel functions of β2-m and β2-m signaling may be common to several solid tumors including human lung, breast, renal, and prostate cancers. Our experimental results could lead to the development of a novel class of antibody-based pharmaceutical agents for cancer growth control. In this review, we briefly summarize the recent data regarding β2-m as a promising new cancer therapeutic target and discuss antagonizing this therapeutic target with antibody therapy for the treatment of localized and disseminated cancers.

Classical chemotherapeutic agents such as mitotic inhibitors (spindle poisons), alkylating agents, antimetabolites, topoisomerase inhibitors, and anthracenediones (anthracyclines) inhibit DNA synthesis and mitosis, thereby killing or impeding the proliferation of rapidly dividing cells. During the last decade, targeted therapy has gained advantage over conventional treatment regimens, as it is more effective against cancer and also much less harmful to normal cells, thus minimizing the side-effects of chemotherapy. This type of treatment blocks the proliferation of cancer cells by inhibiting the function of specific targeted molecules needed for tumor growth and metastasis. Targeted therapy agents include monoclonal antibodies and small-molecule inhibitors, which most commonly target receptor and/or non-receptor tyrosine kinases. Most members of the BCL2 apoptosis-related family regulate cellular fate as a response to antineoplastic agents. Modulations at the mRNA and protein levels of these genes are usually associated with sensitivity or resistance of various types of cancer cells to chemotherapeutic drugs. Moreover, alterations in expression of BCL2-family members, induced by anticancer drug treatment, can trigger or simply facilitate apoptosis. In this review, we summarize information about changes in apoptosis-related gene expression caused directly or indirectly by antineoplastic agents, as well as about the impact of BCL2-family members on the chemosensitivity or chemoresistance of cancer cells.

Natural products display special attributes in the treatment and prevention of a variety of human disorders including cancer. Their therapeutic capacities along with the fact that nature comprises a priceless pool of new compounds have attracted the interest of researchers worldwide. A significant number of organic compounds from terrestrial and marine organisms exhibit anticancer properties as attested by both in vitro and in vivo studies. Emerging evidence supporting the antineoplastic activity of natural compounds has rendered them promising agents in the fight against cancer. As a result, numerous natural compounds or their derivatives have entered clinical practice and are currently in the forefront of chemotherapeutics, showing beneficial effects for cancer patients. Induction of apoptosis seems to be the major mechanism of action induced by these natural agents in the race against cancer. This is mainly achieved through modulations of the expression of B-cell CLL/lymphoma 2 (BCL2) family members. These molecules appear to be the pivotal players determining cellular fate. In the current review, we provide a comprehensive overview of the major alterations in the gene and/or protein levels of BCL2-family members evoked in cancer cells after treatment with a gamut of natural compounds. The data cited suggest the need for exploitation of newly discovered natural products that, along with the improvement of currently employed chemotherapeutics, will significantly enrich the anticancer armamentarium.

Breast and ovarian cancers remain a major public health issue, constituting a major cause of female morbidity and mortality worldwide. Even though systemic chemotherapy remains the main course of action for both types of cancer, current research studies aim at the discovery of novel therapeutic targets. Ribonucleases, due to their apparent implication in gene expression regulation, may serve as potential anticancer drugs. Human RNase κ is an endoribonuclease belonging in a recently identified family of proteins. Recent data from expression microarray studies reveal that the RNase κ gene is found either up- or downregulated in a number of human cancers, indicating a possible diagnostic and/or prognostic utility.The aim of this study was to investigate modulations in the expression levels of RNase κ gene, in breast and ovarian cancer cells, as a response to treatment with different chemotherapeutic agents. BT-20 breast cancer cells and SKOV-3 ovarian cancer cells were treated with the cytotoxic drugs paclitaxel, docetaxel, cisplatin, carboplatin, epirubicin and vinorelbine. Gene expression analysis was performed by the comparative CT method also known as 2–ΔΔCT method. The results revealed a distinct increase in the expression levels of RNase κ mRNA (up to 9-fold) after treatment with the antineoplastic agent paclitaxel in both cell lines, while treatment with the remaining anticancer drugs did not alter drastically the mRNA levels of RNase κ. Based on the fact that paclitaxel exerts its cytotoxic action by inducing apoptosis, the results could be indicative of a potential implication of RNase κ in apoptosis-related pathways.

Effective novel therapeutics is urgently needed due to increasing incidence of malignant cancer and drug multi-resistance. Natural products and their derivatives have historically been a source of pharmaceutical leads and therapeutic drugs. Microtubuletargeting compounds are among the most promising candidates in the combat against cancer. In particular, marine natural products (MNPs) have demonstrated exceptional potency and potential as anticancer agents. Drug discovery from MNPs provides a new pathway to develop original anticancer agents. In this review, seven classes of typical MNPs with diverse structures are summarized. Bioactive marine compounds isolated from different organisms including invertebrate animals, algae, fungi and bacteria are also discussed.

Chemotherapy has been performed to treat metastatic cancers but with varying degrees of success. The optimal potential of chemotherapy has not been achieved yet. Numerous compounds cannot be further developed to produce potent drugs because these compounds exhibit poor druggability. To resolve this issue, researchers developed prodrugs in drug discovery because these drugs can be efficiently used. Many small-molecule prodrugs have been designed and synthesized as anticancer agents for several years, and great progress has been achieved. In this study, recently developed, efficient anticancer prodrugs were reviewed, particularly small molecule prodrugs. Moreover, small molecule anticancer prodrugs were summarized according to different types of chemical structures and properties.

In this review, the literature data on recent advances of the medicinal plant Brucea javanica (L.) Merr. (Simaroubaceae), both phytochemical and biological investigations, are compiled. Brucea javanica is an evergreen shrub distributed widely in Southeast Asia and northern Australia. In China, the seeds of Brucea javanica have been used as traditional herbal medicine due to its multifaceted activities. To date, 153 compounds have been reported from the seeds and aerial parts of Brucea javanica. Quassinoids are the main constituents of this species. The extract of Brucea javanica and the isolated compounds especially quassinoids exhibited various biological properties, such as antitumor and antimalarial effects.

Aliphatic and aromatic ferrocenylthiosemicarbazones were synthesized. The characterization of the new ferrocenylthiosemicarbazones was done by IR, 1H-NMR and 13C-NMR spectroscopy, elemental analysis and X-ray diffraction studies. The biological activity of the obtained compounds was assessed in terms of anticancer activity. Their activity against U251 (human glyoblastoma), PC-3 (human prostatic adenocarcinoma), K562 (human chronic myelogenous leukemia), HCT-15 (human colorectal adenocarcinoma), MCF-7 (human mammary adenocarcinoma) and SKLU-1 (human lung adenocarcinoma) cell lines was studied and compared with cisplatin. All tested compounds showed good activity and the aryl-chloro substituted ferrocenylthiosemicarbazones showed the best anticancer activity.

The identification and in-depth understanding of intracellular signalling pathways led to the synthesis and discovery of many agents targeting cancer cells. In this study, we investigated for the first time the effect of anticancer agent ukrain as a single agent or in combination with cisplatin, etoposide, 5-fluorouracil, quercetin and bortezomib in 4T1 breast cancer and B16F10 melanoma cells. It was found that ukrain is cytotoxic and apoptotic in 4T1 breast carcinoma and B16F10 melanoma cells when given alone. The IC50 value of ukrain in 4T1 cells was found as 40 ± 6.8 μM and that in B16F10 cells as 76 ± 10 μM. It was then found that apoptosis can be induced in 4T1 breast cancer cells in a dose-dependent manner in response to ukrain treatment, based on DNA fragmentation evidence. The induction of apoptosis was corroborated by the analysis of cleavage products of caspase-3 in 4T1 cells using Western blot technique. When ukrain was tested in combination with cisplatin and etoposide, no significant enhancement of cytotoxicity was detected as compared with single agent treatments. Similarly, 5-fluorouracil and quercetin also did not potentiate the cytotoxic effects of ukrain in 4T1 cells. Finally, we examined the effect of various concentrations of ukrain in combination with 10 nM bortezomib in 4T1 cells. Determination of combination index values showed that bortezomib potentiated the effect of ukrain. And the combination was found to cause synergistic cell death. The lowest combination index detected was 0.57 which was obtained when the cells were treated with 10 nM bortezomib + 100 μM ukrain. Likewise, when cells were treated with different doses of bortezomib in the presence of 25 μM ukrain, synergism was similarly detected between the two drugs in a dose-dependent manner. Altogether, the results presented here suggest that the combination of ukrain + bortezomib may be further evaluated and tested in clinical settings.

Glioblastoma Multiforme (GBM) continues to demand improved chemotherapeutic solutions. In order to discover novel chemotherapeutic agents for GBM, we identified novel tetrahydroisoquinoline (THI) analogs as antiglioma agents. The present study reports the design, synthesis and in vitro evaluation of new THI derivatives in four established human glioma cell lines (T98, U87, LN18 and A172). Our structure activity relationship (SAR) studies revealed that the important modification of the carbon linker between the biphenyl and THI ring yielded EDL-360 (12) as a potent antiglioma agent (LN18; IC50: 5.42 ±0.06 μM) and is considered to be our new lead drug candidate for further preclinical studies.

By connection of Regasepin2, a heptapeptide inhibitor of matrix metalloproteinases (MMPs), to the N- or C-terminus of ES-2, an anti-angiogenic peptide of 11 residues, two designed peptides CPU1 and CPU2 were generated. Unexpectedly, CPU2 inhibited MMP-8 and MMP-9 activity in the nanomolar range, whereas CPU1 displayed a weaker inhibitory profile than Regasepin2 against TACE, MMP-8 and MMP-9. CPU1 showed a higher affinity than CPU2 with integrin α5β1 in a HUVEC adhesion assay. In an in vitro angiogenesis model of HUVEC migration, CPU1 showed higher inhibition potency than CPU2 (85% inhibition for CPU1 at a concentration of 0.8 μM versus 17% inhibition for CPU2 at the same concentration). In an in vivo angiogenesis model in chicken egg chorioallantoic membranes, 1.37 μM CPU1 showed a significant inhibition in the formation of new blood vessels, whereas CPU2 and Regasepin2 had no effect on angiogenesis. Furthermore, CPU1 significantly inhibited B16F10 melanoma growth in a syngeneic mouse model (inhibition rate of 56.91% by tumor weight analysis at a dose of 20 mg/kg/d), whereas CPU2 and Regasepin2 did not show any inhibitory effect. In view of recent findings that MMP-9 is pro-angiogenic, our results indicated that the combination of MMP inhibitors and anti-angiogenic peptides may generate novel molecules with potent in vivo anti-tumor effects.