New, exciting developments in experimental therapies in the early 21st century

Novel 3,5-bis(arylidene)-4-oxo-1-piperidinyl dimers: structure-activity relationships and potent antileukemic and antilymphoma cytotoxicity

Novel clusters of 3,5-bis(benzylidene)-4-oxo-1-piperidinyl dimers 3-5 were evaluated against human Molt4/C8 and CEM T-lymphocytes and human HeLa cervix adenocarcinoma cells as well as murine L1210 leukemia neoplasms. Several of these compounds demonstrated IC50 values in the submicromolar and low micromolar range and compounds possessing 4-fluoro, 4-chloro and 3,4,5-trimethoxy substituents in the series 3 and 4 were identified as potent molecules. A heat map revealed the very high cytotoxic potencies of representative compounds against a number of additional leukemic and lymphoma cell lines and displayed greater toxicity to these cells than nonmalignant MCF10A and Hs-27 neoplasms. These dienones are more refractory to breast and prostate cancers. The evaluation of representative compounds in series 3-5 against a panel of human cancer cell lines revealed them to be potent cytotoxins with average IC50 values ranging from 0.05 to 8.51 μM. In particular, the most potent compound 4g demonstrated over 382-fold and 590-fold greater average cytotoxic potencies in this screen than the reference drugs, melphalan and 5-fluorouracil, respectively. A mode of action investigation of two representative compounds 3f and 4f indicated that they induce apoptosis which is due, at least in part, to the activation of caspase-3 and depolarization of the mitochondrial membrane potential.

Cell adhesion molecules and their relation to (cancer) cell stemness

Despite decades of search for anticancer drugs targeting solid tumors, this group of diseases remains largely incurable, especially if in advanced, metastatic stage. In this review, we draw comparison between reprogramming and carcinogenesis, as well as between stem cells (SCs) and cancer stem cells (CSCs), focusing on changing garniture of adhesion molecules. Furthermore, we elaborate on the role of adhesion molecules in the regulation of (cancer) SCs division (symmetric or asymmetric), and in evolving interactions between CSCs and extracellular matrix. Among other aspects, we analyze the role and changes of expression of key adhesion molecules as cancer progresses and metastases develop. Here, the role of cadherins, integrins, as well as selected transcription factors like Twist and Snail is highlighted, not only in the regulation of epithelial-to-mesenchymal transition but also in the avoidance of anoikis. Finally, we briefly discuss recent developments and new strategies targeting CSCs, which focus on adhesion molecules or targeting tumor vasculature.

Autophagy, apoptosis, mitoptosis and necrosis: interdependence between those pathways and effects on cancer

Cell death is a fundamental ingredient of life. Thus, not surprisingly more than one form of cell death exists. Several excellent reviews on various forms of cell death have already been published but manuscripts describing interconnection and interdependence between such processes are uncommon. Here, what follows is a brief introduction on all three classical forms of cell death, followed by a more detailed insight into the role of p53, the master regulator of apoptosis, and other forms of cell death. While discussing p53 and also the role of caspases in cell death forms, we offer insight into the interplay between autophagy and apoptosis, or necrosis, where autophagy may initially serve pro-survival functions. The review moves further to present some details about less researched forms of programmed cell death, namely necroptosis, necrosis and mitoptosis. These "mixed" forms of cell death allow us to highlight the interconnected nature of cell death forms, particularly apoptosis and necrosis. The interdependence between apoptosis, autophagy and necrosis, and their significance for cancer development and treatment are also analyzed in further parts of the review. In the concluding parts, the afore-mentioned issues will be put in perspective for the development of novel anti-cancer therapies.

Interferon-α enhances antitumor activities of oncolytic adenovirus-mediated IL-24 expression in hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) has a dismal 5-year-survival rate of 10%, so novel strategies are warranted. IL-24 mediates anti-tumor activity reducing STAT3 expression, which suggests that interferon (IFN) alpha may augment tumor cell lysis and reduce angiogenesis. We investigated the antitumor activity of treatment with IFN-α, with the oncolytic adenovirus SG600-IL-24, or the combination of both in HCC in vitro and in vivo.

Results

RT-PCR, ELISA assay and Western-blot confirmed that the exogenous IL-24 gene was highly expressed in HCC cells infected with SG600-IL-24. Treatment with combined IFN-α and SG600-IL-24 suppressed growth and promoted apoptosis of the HepG2, MHCC97L, and HCCLM3 cell lines compared with the normal cell line L02. The combined therapy increased STAT1 and SOCS1 and apoptosis, but decreased the expression of the metastatic and angiogenic proteins MMP-2, XIAP, OPN, and VEGF, which are regulated by STAT3 in HCC cells in vitro. To assess the effects in vivo, the HCC cell line HCCLM3 was transplanted subcutaneously into the right flanks of nude mice. Mice in the IFN-α group, the SG600-IL-24 group, or the combined therapy group had significantly suppressed growth of the HCC xenografted tumors compared to the PBS control group of mice. Among the mice treated with the combination of IFN-α and SG600-IL-24, three of those eight mice had long-term survival and no evidence of a tumor. These mice also had decreased expression of the metastatic and angiogenic proteins MMP-2, XIAP, OPN, and VEGF.

Conclusions

The present study demonstrated for the first time the potential antitumor activity of IFN-α combined with the oncolytic adenovirus SG600-IL-24 in HCC both in vitro and in vivo, and suggests its further development as a potential candidate for HCC cancer gene therapy.

A simple mathematical model based on the cancer stem cell hypothesis suggests kinetic commonalities in solid tumor growth

Background

The Cancer Stem Cell (CSC) hypothesis has gained credibility within the cancer research community. According to this hypothesis, a small subpopulation of cells within cancerous tissues exhibits stem-cell-like characteristics and is responsible for the maintenance and proliferation of cancer.

Methodologies/Principal Findings

We present a simple compartmental pseudo-chemical mathematical model for tumor growth, based on the CSC hypothesis, and derived using a “chemical reaction” approach. We defined three cell subpopulations: CSCs, transit progenitor cells, and differentiated cells. Each event related to cell division, differentiation, or death is then modeled as a chemical reaction. The resulting set of ordinary differential equations was numerically integrated to describe the time evolution of each cell subpopulation and the overall tumor growth. The parameter space was explored to identify combinations of parameter values that produce biologically feasible and consistent scenarios.

Conclusions/Significance

Certain kinetic relationships apparently must be satisfied to sustain solid tumor growth and to maintain an approximate constant fraction of CSCs in the tumor lower than 0.01 (as experimentally observed): (a) the rate of symmetrical and asymmetrical CSC renewal must be in the same order of magnitude; (b) the intrinsic rate of renewal and differentiation of progenitor cells must be half an order of magnitude higher than the corresponding intrinsic rates for cancer stem cells; (c) the rates of apoptosis of the CSC, transit amplifying progenitor (P) cells, and terminally differentiated (D) cells must be progressively higher by approximately one order of magnitude. Simulation results were consistent with reports that have suggested that encouraging CSC differentiation could be an effective therapeutic strategy for fighting cancer in addition to selective killing or inhibition of symmetric division of CSCs.

Oncolytic adenovirus SG600-IL24 selectively kills hepatocellular carcinoma cell lines

AIM: To investigate the effect of oncolytic adenovirus SG600-IL24 and replication-incompetent adenovirus Ad.IL-24 on hepatocellular carcinoma (HCC) cell lines and normal liver cell line.

METHODS: HCC cell lines (HepG2, Hep3B and MHCC97L) and normal liver cell line (L02) with a different p53 status were infected with SG600-IL24 and Ad.IL-24, respectively. Melanoma differentiation-associated (MDA)-7/interleukin (IL)-24 mRNA and protein expressions in infected cells were detected by reverse transcription-polymerase chain reaction (RT-PCR), enzyme-linked immunosorbent assay (ELISA), and Western blotting, respectively. Apoptosis of HCC cells and normal liver cells was detected by cytometric assay with Hoechst33258 staining. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to investigate proliferation of HCC cells and normal liver cells, and cell cycle was assayed by flow cytometry.

RESULTS: RT-PCR, ELISA and Western blotting showed that the exogenous MDA-7/IL-24 gene was highly expressed in cells infected with SG600-IL24. MTT indicated that SG600-IL24 could suppress the growth of HepG2, Hep3B, MHCC97L, with an inhibition rate of 75% ± 2.5%, 85% ± 2.0%, 72% ± 1.8%, respectively (P < 0.01), promote the apoptosis of HepG2, Hep3B, MHCC97L, with an apoptosis rate of 56.59% ± 4.0%, 78.36% ± 3.5%, 43.39% ± 2.5%, respectively (P < 0.01), and block the HCC cell lines in the G2/M phase with a blocking rate of 35.4% ± 4.2%, 47.3% ± 6.2%, 42% ± 5.0%, respectively (P < 0.01) but not the normal liver cell line in a p53-independent manner.

CONCLUSION: SG600-IL24 can selectively suppress the proliferation and apoptosis of HCC cell lines in vitro but not normal liver cell line L02 in a p53-independent manner. Compared with Ad.IL-24, SG600-IL24 can significantly enhance the antitumor activity in HCC cell lines.