One signal that is overactivated in a wide range of tumour types is the production of a phospholipid, phosphatidylinositol (3,4,5) trisphosphate, by phosphatidylinositol 3-kinase (PI3K) This lipid and the protein kinase that is activated by it — AKT — trigger a cascade of responses, from cell growth and proliferation to survival and motility, that drive tumour progression Small-molecule therapeutics that block PI3K signalling might deal a severe blow to cancer cells by blocking many aspects of the tumour-cell phenotype

The phosphatidylinositol 3-Kinase AKT pathway in human cancer.

Uncontrolled cell proliferation is the hallmark of cancer, and tumor cells have typically acquired damage to genes that directly regulate their cell cycles. Genetic alterations affecting p16(INK4a) and cyclin D1, proteins that govern phosphorylation of the retinoblastoma protein (RB) and control exit from the G1 phase of the cell cycle, are so frequent in human cancers that inactivation of this pathway may well be necessary for tumor development. Like the tumor suppressor protein p53, components of this "RB pathway," although not essential for the cell cycle per se, may participate in checkpoint functions that regulate homeostatic tissue renewal throughout life.

http://science.sciencemag.org/content/sci/274/5293/1672.full.pdf

Cancer Cell Cycles

Glioblastoma multiforme (GBM) is the most common and lethal type of brain cancer. To identify the genetic alterations in GBMs, we sequenced 20,661 protein coding genes, determined the presence of amplifications and deletions using high-density oligonucleotide arrays, and performed gene expression analyses using next-generation sequencing technologies in 22 human tumor samples. This comprehensive analysis led to the discovery of a variety of genes that were not known to be altered in GBMs. Most notably, we found recurrent mutations in the active site of isocitrate dehydrogenase 1 (IDH1) in 12% of GBM patients. Mutations in IDH1 occurred in a large fraction of young patients and in most patients with secondary GBMs and were associated with an increase in overall survival. These studies demonstrate the value of unbiased genomic analyses in the characterization of human brain cancer and identify a potentially useful genetic alteration for the classification and targeted therapy of GBMs.

http://science.sciencemag.org/content/sci/321/5897/1807.full.pdf

An Integrated Genomic Analysis of Human Glioblastoma Multiforme

Background A recent genomewide mutational analysis of glioblastomas (World Health Organization [WHO] grade IV glioma) revealed somatic mutations of the isocitrate dehydrogenase 1 gene (IDH1) in a fraction of such tumors, most frequently in tumors that were known to have evolved from lower-grade gliomas (secondary glioblastomas). Methods We determined the sequence of the IDH1 gene and the related IDH2 gene in 445 central nervous system (CNS) tumors and 494 non-CNS tumors. The enzymatic activity of the proteins that were produced from normal and mutant IDH1 and IDH2 genes was determined in cultured glioma cells that were transfected with these genes. Results We identified mutations that affected amino acid 132 of IDH1 in more than 70% of WHO grade II and III astrocytomas and oligodendrogliomas and in glioblastomas that developed from these lower-grade lesions. Tumors without mutations in IDH1 often had mutations affecting the analogous amino acid (R172) of the IDH2 gene. Tumors with IDH1 or IDH2 mutations h...

/pdf/idh1-and-idh2-mutations-in-gliomas-1er88anbwg.pdf

IDH1 and IDH2 Mutations in Gliomas

p53, guardian of the genome

Human leukemia U-937/WT cells were exposed to stepwise increased concentrations of Vincristine so that Vincristine-resistant cell sublines (termed U-937/RV) were developed. Established U-937/RV cell sublines have continuously propagated over a year, both in absence and presence of VCR, and have demonstrated similar features. In contrast to U-937/WT cells, U-937/RV cells have longer doubling time, and are more differentiated as determined by appearance of distinct morphological features and synthesis of mRNA that codes for the monocyte colony-stimulating factor-1 receptor (c-fms). Both apoptosis-suppressing Bcl-2 and Bcl-X L proteins were undectable in U-937/WT cells, whereas Bcl-2 was nearly detectable and Bcl-X L readily detectable in U-937/RV cells. The apoptosis-promoting Bax protein was also absent in U-937/WT cells and readily detected in U-937/RV cells. Vincristine-resistant cells with different levels of resistance synthesize similar levels of c-fms mRNA and Bax protein. Finally, unlike U-937/WT cells, U-937/RV cells have no ability to induce tumors when xenografted in immunodeficient mice. The findings collectively suggest that development of resistance to Vincristine in U-937/WT cells may correlate with cell differentiation and synthesis of proteins that regulate apoptosis.

Monocytic differentiation and synthesis of proteins associated with apoptosis in human leukemia U-937 cells acquiring resistance to vincristine.

Anticancer drugs were tested on NIH-2 nude mice inoculated ip with BRO human melanoma cells, which are rapidly lethal for these hosts. Criteria for drug activity were a) increased host survival and b) an increased rate of radioactivity loss from mice bearing BRO cells prelabeled with (/sup 125/I)5-iodo-2'-deoxyuridine. Diphtheria toxin, which is selectively toxic to human cells compared to mouse cells, prolonged host survival and accelerated /sup 125/I elimination in a dose-dependent manner. Drugs that increased the rate of /sup 125/I loss compared to the rate of untreated mice also prolonged the lives of treated mice. With one exception, drugs that did not accelerate /sup 125/I elimination had little or no effect on the length of survival.

Effectiveness of Anticancer Drugs Determined in Nude Mice Inoculated With [125I]5-Iodo-2′-deoxyuridine-Prelabeled Human Melanoma Cells

Human melanomas serially passaged in nude mice as xenotransplants were used as models for the study of the effects of thermochemotherapy of human malignant tumours in vivo. Three such melanomas, one (BRO) fast-growing, one (SCH) slow-growing, and one (BEL) of intermediate growth rate, were chosen. One group was left untreated as a control, one received chemotherapy (cyclophosphamide), one received hyperthermia, and one a combination of both treatments. In all three tumours, the best results were obtained associating chemotherapy with hyperthermia. The fastest growing tumor responded more than the slower, which responded better than the slowest. This model should prove useful in testing the effectiveness of anticancer agents used in association with hyperthermia.

An experimental model for the study of thermochemotherapy in vivo.

CZ48, chemically camptothecin-20-O-propionate hydrate, is currently under clinical investigation. The kinetics of the metabolite camptothecin (CPT) formation and of CZ48 depletion in mouse and human liver microsomes in the presence or absence of NADPH was examined. The formation rate of camptothecin in human liver microsomes was significantly higher than that in mouse with mean Kms of 1.9 and 0.5 nM and Vmaxs of 9.3 and 2.2 pmol/min/mg, respectively. However, the apparent intrinsic clearance (Vmax/Km) ratios for camptothecin in human and mouse liver microsomes were not significantly different from each other (4.9 versus 4.4) in the presence of NADPH. The depletion of CZ48 in human microsomes was four times faster with 4.55% of CZ48 remaining intact while in mouse 19.11% of the drug remained unchanged after 60 min. These results suggest that there is a remarkable species difference of CZ48 biotransformation between human and mouse. The depletion rate of CZ48 in human liver microsomes is considerably higher than that in the mouse.

https://www.mdpi.com/1422-0067/13/5/5498/pdf

Metabolic Difference of CZ48 in Human and Mouse Liver Microsomes

All chemotherapeutic agents currently in use have a narrow window of therapeutic index of 1 to 1.2. Camptothecin estercompounds are reported to have a wider therapeutic index when being used to treat human xenografts in nude mice. As a continuouseffort in searching for better chemotherapeutic agents for treating cancers, new haloalkyl camptothecin and 9-nitrocamptothecin esterderivatives 2a-b and 3a-d were prepared by respective acylation of camptothecin 1a and 9-nitrocamptothecin 1b with the correspondingacylating agents. These new derivatives were tested in vitro against 8 human cancer cell lines using 7 different concentrations rangingfrom 5 to 300 nM and also in vivo against various types of human tumor xenografts grown in nude mice. Most of these new compoundsstarted showing inhibitory effects on the growth of 8 cancer cell lines at concentration of 80 nM and achieved greater than 70%inhibitions against these cell lines when the concentration increased to 300 nM. Compound 2a and 3a showed good activity againsthuman tumor xenografts in nude mice. Compared to mother compound camptothecin, 3a was much less toxic in mice with a bettertherapeutic index, having the potential to be further developed as a safer treatment for cancers.

Beppino C. Giovanella

Papers

Monocytic differentiation and synthesis of proteins associated with apoptosis in human leukemia U-937 cells acquiring resistance to vincristine.

Effectiveness of Anticancer Drugs Determined in Nude Mice Inoculated With [125I]5-Iodo-2′-deoxyuridine-Prelabeled Human Melanoma Cells

An experimental model for the study of thermochemotherapy in vivo.

Metabolic Difference of CZ48 in Human and Mouse Liver Microsomes

Anticancer activity of new haloalkyl camptothecin esters against human cancer cell lines and human tumor xenografts grown in nude mice.