Inhibitors of cyclin-dependent kinases as cancer therapeutics.

Over the past two decades there has been a great deal of interest in the development of inhibitors of the cyclin-dependent kinases (CDKs). This attention initially stemmed from observations that different CDK isoforms have key roles in cancer cell proliferation through loss of regulation of the cell cycle, a hallmark feature of cancer. CDKs have now been shown to regulate other processes, particularly various aspects of transcription. The early non-selective CDK inhibitors exhibited considerable toxicity and proved to be insufficiently active in most cancers. The lack of patient selection biomarkers and an absence of understanding of the inhibitory profile required for efficacy hampered the development of these inhibitors. However, the advent of potent isoform-selective inhibitors with accompanying biomarkers has re-ignited interest. Palbociclib, a selective CDK4/6 inhibitor, is now approved for the treatment of ER+/HER2- advanced breast cancer. Current developments in the field include the identification of potent and selective inhibitors of the transcriptional CDKs; these include tool compounds that have allowed exploration of individual CDKs as cancer targets and the determination of their potential therapeutic windows. Biomarkers that allow the selection of patients likely to respond are now being discovered. Drug resistance has emerged as a major hurdle in the clinic for most protein kinase inhibitors and resistance mechanism are beginning to be identified for CDK inhibitors. This suggests that the selective inhibitors may be best used combined with standard of care or other molecularly targeted agents now in development rather than in isolation as monotherapies

Enhancement of the anti-tumour effect of cyclophosphamide by the bioreductive drugs AQ4N and tirapazamine

The ability of the bioreductive drugs AQ4N and tirapazamine to enhance the anti-tumour effect of cyclophosphamide was assessed in three murine tumour models. In male BDF mice implanted with the T50/80 mammary carcinoma, AQ4N (50–150 mg kg−1) in combination with cyclophosphamide (100 mg kg−1) produced an effect equivalent to a single 200 mg kg−1dose of cyclophosphamide. Tirapazamine (25 mg kg−1) in combination with cyclophosphamide (100 mg kg−1) produced an effect equivalent to a single 150 mg kg−1dose of cyclophosphamide. In C3H mice implanted with the SCCVII or RIF-1 tumours, enhancement of tumour cell killing was found with both drugs in combination with cyclophosphamide (50–200 mg kg−1); AQ4N (50–200 mg kg−1) produced a more effective combination than tirapazamine (12.5–50 mg kg−1). Unlike tirapazamine, which showed a significant increase in toxicity to bone marrow cells, the combination of AQ4N (100 mg kg−1) 6 h prior to cyclophosphamide (100 mg kg−1) resulted in no additional toxicity towards bone marrow cells compared to that caused by cyclophosphamide alone. In conclusion, AQ4N gave a superior anti-tumour effect compared to tirapazamine when administered with a single dose of cyclophosphamide (100 mg kg−1). © 2000 Cancer Research Campaig

Incorporating background frequency improves entropy-based residue conservation measures

BACKGROUND: Several entropy-based methods have been developed for scoring sequence conservation in protein multiple sequence alignments. High scoring amino acid positions may correlate with structurally or functionally important residues. However, amino acid background frequencies are usually not taken into account in these entropy-based scoring schemes. RESULTS: We demonstrate that using a relative entropy measure that incorporates amino acid background frequency results in improved performance in identifying functional sites from protein multiple sequence alignments. CONCLUSION: Our results suggest that the application of appropriate background frequency information may lead to more biologically relevant results in many areas of bioinformatics

Selective accumulation of ALA-induced PpIX and photodynamic effect in chemically induced hepatocellular carcinoma

浜松医科大学学位論文　医博論第397号(平成１７年３月１０日

TNF autovaccination induces self anti-TNF antibodies and inhibits metastasis in a murine melanoma model

TNF is a proinflammatory cytokine involved in the pathogenesis of chronic inflammatory diseases, but also in metastasis in certain types of cancer. In terms of therapy, TNF is targeted by anti-TNF neutralising monoclonal antibodies or soluble TNF receptors. Recently, a novel strategy based on the generation of self anti-TNF antibodies (TNF autovaccination) has been developed. We have previously shown that TNF autovaccination successfully generates high anti-TNF antibody titres, blocks TNF and ameliorates collagen-induced arthritis in DBA/1 mice. In this study, we examined the ability of TNF autovaccination to generate anti-TNF antibody titres and block metastasis in the murine B16F10 melanoma model. We found that immunisation of C57BL/6 mice with TNF autovaccine produces a 100-fold antibody response to TNF compared to immunisation with phosphate-buffered saline vehicle control and significantly reduces both the number (P<0.01) and size of metastases (P<0.01) of B16F10 melanoma cells. This effect is also observed when an anti-TNF neutralising monoclonal antibody is administered, confirming the essential role TNF plays in metastasis in this model. This study suggests that TNF autovaccination is a cheaper and highly efficient alternative that can block TNF and reduce metastasis in vivo and trials with TNF autovaccination are already underway in patients with metastatic cancer

Pharmacokinetic behaviour of the chemoprotectants BNP7787 and mesna after an i.v. bolus injection in rats

0.01). In conclusion, the five-fold higher AUC of mesna in plasma after mesna administration and the fact that mesna is more reactive with (hydrated) cisplatin than its disulphide form BNP7787 represent a plausible explanation as to why mesna administration can reduce the antitumour activity of cisplatin. After BNP7787 administration, the distribution of BNP7787 and mesna was restricted to the kidney, which confirmed the selective protection of the kidney by BNP7787

Strong interface-induced spin-orbit coupling in graphene on WS2

Interfacial interactions allow the electronic properties of graphene to be modified, as recently demonstrated by the appearance of satellite Dirac cones in the band structure of graphene on hexagonal boron nitride (hBN) substrates. Ongoing research strives to explore interfacial interactions in a broader class of materials in order to engineer targeted electronic properties. Here we show that at an interface with a tungsten disulfide (WS2) substrate, the strength of the spin-orbit interaction (SOI) in graphene is very strongly enhanced. The induced SOI leads to a pronounced low-temperature weak anti-localization (WAL) effect, from which we determine the spin-relaxation time. We find that spin-relaxation time in graphene is two-to-three orders of magnitude smaller on WS2 than on SiO2 or hBN, and that it is comparable to the intervalley scattering time. To interpret our findings we have performed first-principle electronic structure calculations, which both confirm that carriers in graphene-on-WS2 experience a strong SOI and allow us to extract a spin-dependent low-energy effective Hamiltonian. Our analysis further shows that the use of WS2 substrates opens a possible new route to access topological states of matter in graphene-based systems.Comment: Originally submitted version in compliance with editorial guidelines. Final version with expanded discussion of the relation between theory and experiments to be published in Nature Communication

Inhibition of IGF-1R-dependent PI3K activation sensitizes colon cancer cells specifically to DR5-mediated apoptosis but not to rhTRAIL

Background: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) initiates apoptosis in tumor cells upon binding to its cognate agonistic receptors, death receptors 4 and 5 (DR4 and DR5). The activity of the insulin-like growth factor 1 (IGF-1) survival pathway is often increased in cancer, influencing both cell proliferation and apoptosis. We hypothesized that inhibiting the IGF-1 receptor (IGF-1R) using NVP-AEW541, a small molecular weight tyrosine kinase inhibitor of the IGF-1R, could increase death receptor (DR)-mediated apoptosis in colon cancer cells