Small molecule FGF receptor inhibitors block FGFR-dependent urothelial carcinoma growth in vitro and in vivo

BACKGROUND

Activating mutations of FGFR3 are frequently identified in superficial urothelial carcinoma (UC) and increased expression of FGFR1 and FGFR3 are common in both superficial and invasive UC.

METHODS

The effects of inhibition of receptor activity by three small molecule inhibitors (PD173074, TKI-258 and SU5402) were investigated in a panel of bladder tumour cell lines with known FGFR expression levels and FGFR3 mutation status.

RESULTS

All inhibitors prevented activation of FGFR3, and inhibited downstream MAPK pathway signalling. Response was related to FGFR3 and/or FGFR1 expression levels. Cell lines with the highest levels of FGFR expression showed the greatest response and little or no effect was measured in normal human urothelial cells or in UC cell lines with activating RAS gene mutations. In sensitive cell lines, the drugs induced cell cycle arrest and/or apoptosis. IC(50) values for PD173074 and TKI-258 were in the nanomolar concentration range compared with micromolar concentrations for SU5402. PD173074 showed the greatest effects in vitro and in vivo significantly delayed the growth of subcutaneous bladder tumour xenografts.

CONCLUSION

These results indicate that inhibition of FGFR1 and wild-type or mutant FGFR3 may represent a useful therapeutic approach in patients with both non-muscle invasive and muscle invasive UC.

Organometallic osmium arene complexes with potent cancer cell cytotoxicity

Iodido osmium(II) complexes [Os(η(6)-arene)(XY)I](+) (XY = p-hydroxy or p-dimethylaminophenylazopyridine, arene = p-cymene or biphenyl) are potently cytotoxic at nanomolar concentrations toward a panel of human cancer cell lines; e.g., IC(50) = 140 nM for [Os(η(6)-bip)(azpy-NMe(2))I](+) toward A2780 ovarian cancer cells. They exhibit low toxicity and negligible deleterious effects in a colon cancer xenograft model, giving rise to the possibility of a broad therapeutic window. The most active complexes are stable and inert toward aquation. Their cytotoxic activity appears to involve redox mechanisms.

Polysialyltransferase: a new target in metastatic cancer

Polysialic acid (polySia) is a carbohydrate polymer critical for neuronal cell migration and axon pathfinding in embryonic development. Besides brain regions requiring persistent neuronal plasticity, polySia is essentially absent from the adult body. However, polySia is aberrantly re-expressed on many tumours, where it decorates the surface of NCAM (neuronal cell adhesion molecule) and modulates cell adhesion, migration and invasion. PolySia-NCAM expression is strongly associated with poor clinical prognosis and correlates with aggressive and invasive disease in many cancers, including lung cancer, neuroblastoma and gliomas. The synthesis of polySia is mediated by two polysialyltransferases (polySTs), ST8SiaIV (PST) and particularly ST8SiaII (STX) in cancer cells. The demonstration that polyST knock-down negates events associated with tumour cell dissemination indicates that PST and STX are validated targets. Selective inhibition of polySTs therefore presents a therapeutic opportunity to inhibit tumour invasion and metastasis.

Synthesis of Some Cryptolepine Analogues, Assessment of Their Antimalarial and Cytotoxic Activities, and Consideration of Their Antimalarial Mode of Action

A series of analogues of cryptolepine (1) have been synthesized and evaluated for their in vitro antiplasmodial and cytotoxic properties. The IC(50) values of several compounds (11a, 11k-m, 11o, 13) against Plasmodium falciparum (strain K1) were <0.1 muM, 5-10-fold lower than that of 1 but their cytotoxicities were only 2-4 times greater than that of 1. Compounds with a halogen in the quinoline ring and a halogen or a nitro group in the indole ring have enhanced antiplasmodial activity. In mice infected with P. berghei, the 7-bromo-2-chloro (11k) and 2-bromo-7-nitro (13) derivatives of 1 suppressed parasitemia by >90% at doses of 25 mg kg(-1) day(-1) with no apparent toxicity to the mice. 2,7-Dibromocryptolepine (15) was evaluated at several dose levels, and a dose-dependent suppression of parasitemia was seen (ED(90) = 21.6 mg kg(-1) day(-1)). The antimalarial mode of action of 1 appears to be similar to that of chloroquine and involves the inhibition of hemozoin formation. A number of analogues were assessed for their effects on the inhibition of beta-hematin (hemozoin) formation, and the results were compared with their antiplasmodial activities having taken account of their predicted accumulation into the acidic parasite food vacuole. No correlation was seen (r(2) = 0.0781) suggesting that the potent antimalarial activity of compounds such as 15 involves other mechanisms in addition to the inhibition of hemozoin formation.

Quantitative Angiogenesis Assays in vivo – A Review

The development of agents that target tumour vasculature is ultimately dependent on the availability of appropriate preclinical screening assays. Several quantitative angiogenesis assays exist, each with its own unique characteristics and disadvantages. In this review we discuss some of the commonly used assays, their methodological pitfalls and current use. The corneal micropocket and the CAM assay are well established. However, the matrix-implant assays have the potential advantage of replicating the hypoxic tumour microenvironment, thus making them suitable for the study of tumour angiogenesis. The ideal quantitative angiogenesis assay does not exist and the use of two complimentary quantitative assays, such as a matrix implant assay and a microcirculatory preparation like the CAM or corneal micropocket assay, provides the best compromise. Newer models like the hollow-fibre assay are being developed and older ones refined. Assay systems should reflect distinct disease processes. Thus it is appropriate to develop assays that study exclusively pro- or anti-angiogenic compounds or anti-vascular agents. Criticisms of currently available screening systems are that the predictive value of current screening systems remains to be established as anti-angiogenic agents are still in clinical development. Anti-angiogenic agents are likely to be most effective as chronic therapy for remission maintenance in the metastatic setting or as adjuvant therapy in patients at high risk of relapse, an important clinical aspect not addressed in animal models of tumour angiogenesis. Histological analysis still provides the most detailed information on in vivo angiogenesis. However, angiogenesis is a dynamic process and assays that permit continuous monitoring of the angiogenic response and provide information on the physiological characteristics of new vessels will be distinctly advantageous over older systems. The development of non-invasive techniques for quantitation of angiogenesis will greatly facilitate this process.

Non-invasive molecular imaging for preclinical cancer therapeutic development

Molecular and non-invasive imaging are rapidly emerging fields in preclinical cancer drug discovery. This is driven by the need to develop more efficacious and safer treatments, the advent of molecular-targeted therapeutics, and the requirements to reduce and refine current preclinical in vivo models. Such bioimaging strategies include MRI, PET, single positron emission computed tomography, ultrasound, and optical approaches such as bioluminescence and fluorescence imaging. These molecular imaging modalities have several advantages over traditional screening methods, not least the ability to quantitatively monitor pharmacodynamic changes at the cellular and molecular level in living animals non-invasively in real time. This review aims to provide an overview of non-invasive molecular imaging techniques, highlighting the strengths, limitations and versatility of these approaches in preclinical cancer drug discovery and development.

Design, Synthesis, and Biophysical and Biological Evaluation of a Series of Pyrrolobenzodiazepine−Poly(N-methylpyrrole) Conjugates

A novel series of methyl ester-terminated C8-linked pyrrolobenzodiazepine (PBD)-poly(N-methylpyrrole) conjugates (50a-f) has been synthesized and their DNA interaction evaluated by thermal denaturation, DNA footprinting, and in vitro transcription stop assays. The synergistic effect of attaching a PBD unit to a polypyrrole fragment is illustrated by the large increase in DNA binding affinity (up to 50-fold) compared to the individual PBD and pyrrole components. 50a-f were found to bind mainly to identical DNA sequences but with apparent binding site widths increasing with molecular length and the majority of sites conforming to the consensus motif 5'-XGXWz (z = 3 +/- 1; W = A or T; X = any base but preferably a purine). They also provided robust sequence-selective blockade of transcription at sites corresponding approximately to their DNA footprints. 50a-f were shown to have good cellular/nuclear penetration properties, and a degree of correlation between cytotoxicity and DNA-binding affinity was observed.

Heparin octasaccharides inhibit angiogenesis in vivo

BACKGROUND

In previous experiments, we showed that heparin oligosaccharides inhibit the angiogenic cytokine fibroblast growth factor-2. Here, we present the first in vivo study of size-fractionated heparin oligosaccharides in four models of angiogenesis that are progressively less dependent on fibroblast growth factor-2.

EXPERIMENTAL DESIGN

Heparin oligosaccharides were prepared using size-exclusion gel filtration chromatography and characterized through depolymerization and strong anion exchange high-performance liquid chromatography. Size-defined oligosaccharides (20 mg/kg/d) were given to mice bearing s.c. sponges that were injected with fibroblast growth factor-2 (100 ng/d). After 14 days, octasaccharides and decasaccharides reduced the microvessel density to levels below control. In a second experiment, HEC-FGF2 human endometrial cancer cells that overexpress fibroblast growth factor-2 were implanted in a hollow fiber placed s.c. in vivo. Oligosaccharides were given at 20 mg/kg/d for 2 weeks and the data again showed that octasaccharides significantly reduced microvessel density around the fiber (P = 0.03). In a more complex model, where angiogenesis was induced by a broad spectrum of growth factors, including vascular endothelial growth factor, we implanted H460 lung carcinoma cells in hollow fibers and treated the animals with oligosaccharides at 20 mg/kg/d over 3 weeks. Octasaccharides reduced the microvessel density to that of control. Preliminary investigation of 6-O-desulfated heparins showed that these also had antiangiogenic activity.

RESULTS

Finally, we examined the inhibitory potential of hexasaccharides and octasaccharides given at 20 mg/kg/d and these inhibited the growth of H460 lung carcinoma in vivo. At clinically attainable concentrations, significant anticoagulation (activated partial thromboplastin time, anti-factor Xa, and anti-factor IIa) was not observed in vitro unless species containing > or =16 saccharide residues were investigated.

CONCLUSIONS

Thus, our preclinical data show that heparin octasaccharides represent novel antiangiogenic compounds that can be given without the anticoagulant effects of low molecular weight heparin.

ERp29 is a ubiquitous resident of the endoplasmic reticulum with a distinct role in secretory protein production

ERp29 was recently characterized biochemically as a novel protein that resides in mammalian endoplasmic reticulum (ER). Here we applied immunochemical procedures at the cellular level to investigate the hypothesized role of ERp29 in secretory protein production. ERp29 was localized exclusively to the ER/nuclear envelope of MDCK cells using confocal immunocytochemistry and comparative markers of the ER lumen, ER/Golgi membrane, nuclei, and mitochondria. A predominant association with rough ER was revealed by sucrose-gradient analysis of rat liver microsomes. Immunohistochemistry showed ERp29 expression in 35 functionally distinct cell types of rat, establishing ERp29 as a general ER marker. The ERp29 expression profile largely paralleled that of protein disulfide isomerase (PDI), the closest relative of ERp29, consistent with a role in secretory protein production. However strikingly different ERp29/PDI ratios were observed in various cell types, suggesting independent regulation and functional roles. Together, these findings associate ERp29 primarily with the early stages of secretory protein production and implicate ERp29 in a distinct functional role that is utilized in most cells. Our identification of several ERp29-enriched cell types suggests a potential selectivity of ERp29 for non-collagenous substrates and provides a physiological foundation for future investigations.

Pharmacological inhibition of polysialyltransferase ST8SiaII modulates tumour cell migration

Polysialic acid (polySia), an α-2,8-glycosidically linked polymer of sialic acid, is a developmentally regulated post-translational modification predominantly found on NCAM (neuronal cell adhesion molecule). Whilst high levels are expressed during development, peripheral adult organs do not express polySia-NCAM. However, tumours of neural crest-origin re-express polySia-NCAM: its occurrence correlates with aggressive and invasive disease and poor clinical prognosis in different cancer types, notably including small cell lung cancer (SCLC), pancreatic cancer and neuroblastoma. In neuronal development, polySia-NCAM biosynthesis is catalysed by two polysialyltransferases, ST8SiaII and ST8SiaIV, but it is ST8SiaII that is the prominent enzyme in tumours. The aim of this study was to determine the effect of ST8SiaII inhibition by a small molecule on tumour cell migration, utilising cytidine monophosphate (CMP) as a tool compound. Using immunoblotting we showed that CMP reduced ST8iaII-mediated polysialylation of NCAM. Utilizing a novel HPLC-based assay to quantify polysialylation of a fluorescent acceptor (DMB-DP3), we demonstrated that CMP is a competitive inhibitor of ST8SiaII (K i = 10 µM). Importantly, we have shown that CMP causes a concentration-dependent reduction in tumour cell-surface polySia expression, with an absence of toxicity. When ST8SiaII-expressing tumour cells (SH-SY5Y and C6-STX) were evaluated in 2D cell migration assays, ST8SiaII inhibition led to significant reductions in migration, while CMP had no effect on cells not expressing ST8SiaII (DLD-1 and C6-WT). The study demonstrates for the first time that a polysialyltransferase inhibitor can modulate migration in ST8SiaII-expressing tumour cells. We conclude that ST8SiaII can be considered a druggable target with the potential for interfering with a critical mechanism in tumour cell dissemination in metastatic cancers.

Development of a novel tumor-targeted vascular disrupting agent activated by membrane-type matrix metalloproteinases

Vascular disrupting agents (VDA) offer a strategy to starve solid tumors of nutrients and oxygen concomitant with tumor shrinkage. Several VDAs have progressed into early clinical trials, but their therapeutic value seems to be compromised by systemic toxicity. In this report, we describe the design and characterization of a novel VDA, ICT2588, that is nontoxic until activated specifically in the tumor by membrane-type 1 matrix metalloproteinase (MT1-MMP). HT1080 cancer cells expressing MT1-MMP were selectively chemosensitive to ICT2588, whereas MCF7 cells that did not express MT1-MMP were nonresponsive. Preferential hydrolysis of ICT2588 to its active metabolite (ICT2552) was observed in tumor homogenates of HT1080 relative to MCF7 homogenates, mouse plasma, and liver homogenate. ICT2588 activation was inhibited by the MMP inhibitor ilomastat. In HT1080 tumor-bearing mice, ICT2588 administration resulted in the formation of the active metabolite, diminution of tumor vasculature, and hemorrhagic necrosis of the tumor. The antitumor activity of ICT2588 was superior to its active metabolite, exhibiting reduced toxicity, improved therapeutic index, enhanced pharmacodynamic effect, and greater efficacy. Coadministration of ICT2588 with doxorubicin resulted in a significant antitumor response (22.6 d growth delay), which was superior to the administration of ICT2588 or doxorubicin as a single agent, including complete tumor regressions. Our findings support the clinical development of ICT2588, which achieves selective VDA targeting based on MT-MMP activation in the tumor microenvironment.

Synthesis of DNA-directed pyrrolidinyl and piperidinyl confined alkylating chloroalkylaminoanthraquinones: potential for development of tumor-selective N-oxides

A novel series of 1,4-disubstituted chloroethylaminoanthraquinones, containing alkylating chloroethylamino functionalities as part of a rigid piperidinyl or pyrrolidinyl ring-system, have been prepared. The target compounds were prepared by ipso-displacement of halides of various anthraquinone chromophores by either hydroxylated or chlorinated piperidinyl- or pyrrolidinyl-alkylamino side chains. The chloroethylaminoanthraquinones were shown to alkylate guanine residues of linearized pBR322 (1-20 microM), and two symmetrically 1,4-disubstituted anthraquinones (compounds 14 and 15) were shown to interstrand cross-link DNA in the low nM range. Several 1,4-disubstituted chloroethylaminoanthraquinones were potently cytotoxic (IC50 values: <or=40 nM) in human ovarian cancer A2780 cells. Two agents (compounds 18 and 19) exhibited mean GI50 values of 96 nM and 182 nM, respectively, in the NCI human tumor cell line panel. Derivatization of the potent DNA cross-linking agent 15 to an N-oxide resulted in loss of the DNA unwinding, DNA interstrand cross-linking and cytotoxic activity of the parent molecule.

In vivo activation of the hypoxia-targeted cytotoxin AQ4N in human tumor xenografts

AQ4N (banoxantrone) is a prodrug that, under hypoxic conditions, is enzymatically converted to a cytotoxic DNA-binding agent, AQ4. Incorporation of AQ4N into conventional chemoradiation protocols therefore targets both oxygenated and hypoxic regions of tumors, and potentially will increase the effectiveness of therapy. This current pharmacodynamic and efficacy study was designed to quantify tumor exposure to AQ4 following treatment with AQ4N, and to relate exposure to outcome of treatment. A single dose of 60 mg/kg AQ4N enhanced the response of RT112 (bladder) and Calu-6 (lung) xenografts to treatment with cisplatin and radiation therapy. AQ4N was also given to separate cohorts of tumor-bearing mice 24 hours before tumor excision for subsequent analysis of metabolite levels. AQ4 was detected by high performance liquid chromatography/mass spectrometry in all treated samples of RT112 and Calu-6 tumors at mean concentrations of 0.23 and 1.07 microg/g, respectively. These concentrations are comparable with those shown to be cytotoxic in vitro. AQ4-related nuclear fluorescence was observed in all treated tumors by confocal microscopy, which correlated with the high performance liquid chromatography/mass spectrometry data. The presence of the hypoxic marker Glut-1 was shown by immunohistochemistry in both Calu-6 tumors and RT112 tumors, and colocalization of AQ4 fluorescence and Glut-1 staining strongly suggested that AQ4N was activated in these putatively hypoxic areas. This is the first demonstration that AQ4N will increase the efficacy of chemoradiotherapy in preclinical models; the intratumoral levels of AQ4 found in this study are comparable with tumor AQ4 levels found in a recent phase I clinical study, which suggests that these levels could be potentially therapeutic.

Guaianolide sesquiterpenes from Pulicaria crispa (Forssk.) Oliv

A phytochemical study of the asteraceous herb Pulicaria crispa (Forssk.) Oliv. resulted in the characterisation of three guaianolide sesquiterpenes, 2alpha,4alpha-dihydroxy-7alphaH,8alphaH,10alphaH-guaia-1(5),11(13)-dien-8beta,12-olide (1), 1alpha,2alpha-epoxy-4beta-hydroxy-5alphaH,7alphaH,8alphaH,10alphaH-guaia-11(13)-en-8beta,12-olide (2) and 5,10-epi-2,3-dihydroaromatin (3). The structures were assigned on the basis of extensive 1 and 2D NMR experiments. Compound 3 exhibited weak antimycobacterial activity against Mycobacterium phlei with a minimum inhibitory concentration of 0.52 mM and cytotoxicity (IC50 of 5.8+/-0.2 microM) in a human bladder carcinoma cell line, EJ-138.

Triplex profiling of functionally distinct chaperones (ERp29/PDI/BiP) reveals marked heterogeneity of the endoplasmic reticulum proteome in cancer

The biomedical need for streamlined approaches to monitor proteome dynamics is growing rapidly. This study examined the ability of a knowledge-based triplex-profiling strategy (i.e., three functionally distinct chaperones, ERp29/PDI/BiP) to clarify uncertainties about how cancer affects the endoplasmic reticulum (ER) proteome. Investigating a wide range of samples at the tissue and cellular levels (>114 samples from 9 tissues of origin), we obtained consistent evidence that the ER proteome undergoes a major but variable expansion in cancer. Three factors having a strong influence on the ER proteome were identified (cancer-cell type, growth rate, culture mode), and the functionally enigmatic chaperone ERp29 was linked distinctively to histogenetic aspects of tumorigenesis. These findings justify pursuit of the ER-proteome as a medical target in cancer, validate ERp29/PDI/BiP profiling as a streamlined yet powerful measure of ER-proteome dynamics, and suggest that biomarker sets based on distinct functionalities could have broader biomedical utility.

Pharmacological and biological evaluation of a series of substituted 1,4-naphthoquinone bioreductive drugs

The indolequinone compound EO9 has good pharmacodynamic properties in terms of bioreductive activation and selectivity for either NAD(P)H:quinone oxidoreductase-1 (NQO1)-rich aerobic or NQO1-deficient hypoxic cells. However, its pharmacokinetic properties are poor and this fact is believed to be a major reason for EO9's lack of clinical efficacy. The purpose of this study was to develop quinone-based bioreductive drugs that retained EO9's good properties, in terms of bioreductive activation, but have improved pharmacokinetic properties. Out of 11 naphthoquinone compounds evaluated, 2-aziridinyl-5-hydroxy-1,4-naphthoquinone (compound 2), 2,3-bis(aziridinyl)-5-hydroxy-1,4-naphthoquinone (compound 3), and 2-aziridinyl-6-hydroxymethyl-1,4-naphthoquinone (compound 11) were selected for further evaluation based on good substrate specificity for NQO1 and selectivity towards NQO1-rich cells in vitro. Compound 3 was of particular interest as it also demonstrated selectivity for NQO1-rich cells under hypoxic conditions. Compound 3 was not metabolised by murine whole blood in vitro (in contrast to compounds 2, 11 and EO9) and pharmacokinetic studies in non-tumour-bearing mice in vivo (at the maximum soluble dose of 60 mg kg(-1) administered intraperitoneally) demonstrated significant improvements in plasma half-life (16.2 min) and AUC values (22.5 microM h) compared to EO9 (T(1/2) = 1.8 min, AUC = 0.184 microM h). Compound 3 also demonstrated significant anti-tumour activity against H460 and HCT-116 human tumour xenografts in vivo, whereas EO9 was inactive against these tumours. In conclusion, compound 3 is a promising lead compound that may target both aerobic and hypoxic fractions of NQO1-rich tumours and further studies to elucidate its mechanism of action and improve solubility are warranted.

Agarose Spot as a Comparative Method for in situ Analysis of Simultaneous Chemotactic Responses to Multiple Chemokines

We describe a novel protocol to quantitatively and simultaneously compare the chemotactic responses of cells towards different chemokines. In this protocol, droplets of agarose gel containing different chemokines are applied onto the surface of a Petri dish, and then immersed under culture medium in which cells are suspended. As chemokine molecules diffuse away from the spot, a transient chemoattractant gradient is established across the spots. Cells expressing the corresponding cognate chemokine receptors migrate against this gradient by crawling under the agarose spots towards their centre. We show that this migration is chemokine-specific; meaning that only cells that express the cognate chemokine cell surface receptor, migrate under the spot containing its corresponding chemokine ligand. Furthermore, we show that migration under the agarose spot can be modulated by selective small molecule antagonists present in the cell culture medium.

Tumor-targeted prodrug ICT2588 demonstrates therapeutic activity against solid tumors and reduced potential for cardiovascular toxicity

Development of therapeutic strategies for tumor-selective delivery of therapeutics through exploitation of the proteolytic tumor phenotype has significant scope for improvement of cancer treatment. ICT2588 is a peptide-conjugated prodrug of the vascular disrupting agent (VDA) azademethylcolchicine developed to be selectively hydrolyzed by matrix metalloproteinase-14 (MMP-14) within the tumor. In this report, we extend our previous proof-of-concept studies and demonstrate the therapeutic potential of this agent against models of human colorectal, lung, breast, and prostate cancer. In all tumor types, ICT2588 was superior to azademethylcolchicine and was greater or comparable to standard clinically used agents for the respective tumor type. Prodrug activation in clinical human lung tumor homogenates relative to stability in human plasma and liver was observed, supporting clinical translation potential. A major limiting factor to the clinical value of VDAs is their inherent cardiovascular toxicity. No increase in plasma von Willebrand factor (vWF) levels, an indicator of systemic vascular dysfunction and acute cardiovascular toxicity, was detected with ICT2588, thereby supporting the tumor-selective activation and reduced potential of ICT2588 to cause cardiovascular toxicity. Our findings reinforce the improved therapeutic index and tumor-selective approach offered by ICT2588 and this nanotherapeutic approach.

PIK3CA dependence and sensitivity to therapeutic targeting in urothelial carcinoma

Background

Many urothelial carcinomas (UC) contain activating PIK3CA mutations. In telomerase-immortalized normal urothelial cells (TERT-NHUC), ectopic expression of mutant PIK3CA induces PI3K pathway activation, cell proliferation and cell migration. However, it is not clear whether advanced UC tumors are PIK3CA-dependent and whether PI3K pathway inhibition is a good therapeutic option in such cases.

Methods

We used retrovirus-mediated delivery of shRNA to knock down mutant PIK3CA in UC cell lines and assessed effects on pathway activation, cell proliferation, migration and tumorigenicity. The effect of the class I PI3K inhibitor GDC-0941 was assessed in a panel of UC cell lines with a range of known molecular alterations in the PI3K pathway.

Results

Specific knockdown of PIK3CA inhibited proliferation, migration, anchorage-independent growth and in vivo tumor growth of cells with PIK3CA mutations. Sensitivity to GDC-0941 was dependent on hotspot PIK3CA mutation status. Cells with rare PIK3CA mutations and co-occurring TSC1 or PTEN mutations were less sensitive. Furthermore, downstream PI3K pathway alterations in TSC1 or PTEN or co-occurring AKT1 and RAS gene mutations were associated with GDC-0941 resistance.

Conclusions

Mutant PIK3CA is a potent oncogenic driver in many UC cell lines and may represent a valuable therapeutic target in advanced bladder cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2570-0) contains supplementary material, which is available to authorized users.

In vitro and in vivo activity of LS 4477 and LS 4559, novel analogues of the tubulin binder estramustine

LS 4477 and LS 4559, two of a series of N-acyl-aminoalkyl phenyl ethers, are rationally designed compounds based on the tubulin binder estramustine. This study investigated their mechanism of action and compared their effectiveness in relation to estramustine in vitro against a panel of human and murine cell lines and in vivo against two murine colon tumour models (MAC). At biologically relevant concentrations, LS 4477 and LS 4559 caused a 59.9 and 56% reduction in tubulin assembly, respectively, compared with a 28.4% reduction in tubulin assembly by estramustine. The analogues were approximately 100 times more potent in chemosensitivity tests in vitro than the parent compound. Both analogues were orally active against the MAC 15A murine tumour model, to a greater extent than estramustine, producing significant growth delays (P<0.01). Significant activity was also shown against the slower growing MAC 26 tumour for LS 4577 (the soluble pro-drug of LS 4559). The results presented in this study suggest these compounds warrant further development with a view to assessing their clinical activity.

RGD-Binding Integrins in Head and Neck Cancers

Alterations in integrin expression and function promote tumour growth, invasion, metastasis and neoangiogenesis. Head and neck cancers are highly vascular tumours with a tendency to metastasise. They express a wide range of integrin receptors. Expression of the αv and β1 subunits has been explored relatively extensively and linked to tumour progression and metastasis. Individual receptors αvβ3 and αvβ5 have proved popular targets for diagnostic and therapeutic agents but lesser studied receptors, such as αvβ6, αvβ8, and β1 subfamily members, also show promise. This review presents the current knowledge of integrin expression and function in squamous cell carcinoma of the head and neck (HNSCC), with a particular focus on the arginine-glycine-aspartate (RGD)-binding integrins, in order to highlight the potential of integrins as targets for personalised tumour-specific identification and therapy.