Synergistic therapeutic effect of cisplatin and phosphatidylinositol 3-kinase (PI3K) inhibitors in cancer growth and metastasis of Brca1 mutant tumors

C-type natriuretic peptide (CNP) inhibits 7,12-Dimethylbenz[a]anthracene (DMBA)/Croton oil-induced skin tumor growth by modulating inflammation in Swiss albino mice

C-type natriuretic peptide (CNP) exhibits anti-inflammatory activity besides its natriuretic and diuretic functions. The present study aimed to determine the anticancer and synergistic therapeutic activity of CNP against a 7,12-Dimethylbenz[a]anthracene (DMBA)/Croton oil-induced skin tumor mouse model. CNP (2.5 µg/kg body weight) was injected either alone and/or in combination with Cisplatin (CDDP) (2 mg/kg body weight) for 4 weeks. The dorsal skin tumor incidences/growth and mortality rate were recorded during the experimental period of 16 weeks. The serum C-reactive protein (CRP), and lactate dehydrogenase (LDH) levels, infiltrating mast cells, and AgNORs proliferating cells count were analyzed in control and experimental mice. Further, the expression profile of marker genes of proliferation, inflammation, and progression molecules were analyzed using Reverse transcriptase-polymerase chain reaction (RT-PCR)/quantitative PCR (qPCR), western blot, and immunohistochemistry. The DMBA/Croton oil-induced mice exhibited 100% tumor incidence. Whereas, CNP alone, CDDP alone, and CNP+CDDP combination-treated mice exhibited 58%, 46%, and 24% tumor incidence, respectively. Also, a marked reduction in the levels of serum CRP and LDH, the number of infiltrating mast cells count and AgNORs proliferating cells count were noticed in the mice skin sections. Further, a significant reduction in both mRNA and protein expression levels of proliferation, inflammation, and progression markers were noticed in CNP (p < 0.01), CDDP (p < 0.01), and CNP+CDDP combination (p < 0.001) treated mice, respectively. The results of the present study suggest that CNP has anticancer activity. Further, the CNP+CDDP treatment has more promising anticancer activity as compared with CNP or CDDP alone treatment, probably due to the synergistic antiproliferative and anti-inflammatory activities of CNP and CDDP.

Engine shutdown: migrastatic strategies and prevention of metastases

Most cancer-related deaths among patients with solid tumors are caused by metastases. Migrastatic strategies represent a unique therapeutic approach to prevent all forms of cancer cell migration and invasion. Because the migration machinery has been shown to promote metastatic dissemination, successful migrastatic therapy may reduce the need for high-dose cytotoxic therapies that are currently used to prevent the risk of metastatic dissemination. In this review we focus on anti-invasive and antimetastatic strategies that hold promise for the treatment of solid tumors. The best targets for migrastatic therapy would be those that are required by all forms of motility, such as ATP availability, mitochondrial metabolism, and cytoskeletal dynamics and cell contractility.

Cancer as a biophysical disease: Targeting the mechanical-adaptability program

With the number of cancer cases projected to significantly increase over time, researchers are currently exploring "nontraditional" research fields in the pursuit of novel therapeutics. One emerging area that is steadily gathering interest revolves around cellular mechanical machinery. When looking broadly at the physical properties of cancer, it has been debated whether a cancer could be defined as either stiffer or softer across cancer types. With numerous articles supporting both sides, the evidence instead suggests that cancer is not particularly regimented. Instead, cancer is highly adaptable, allowing it to endure the constantly changing microenvironments cancer cells encounter, such as tumor compression and the shear forces in the vascular system and body. What allows cancer cells to achieve this adaptability are the particular proteins that make up the mechanical network, leading to a particular mechanical program of the cancer cell. Coincidentally, some of these proteins, such as myosin II, α-actinins, filamins, and actin, have either altered expression in cancer and/or some type of direct involvement in cancer progression. For this reason, targeting the mechanical system as a therapeutic strategy may lead to more efficacious treatments in the future. However, targeting the mechanical program is far from trivial. As involved as the mechanical program is in cancer development and metastasis, it also helps drive many other key cellular processes, such as cell division, cell adhesion, metabolism, and motility. Therefore, anti-cancer treatments targeting the mechanical program must take great care to avoid potential side effects. Here, we introduce the potential of targeting the mechanical program while also providing its challenges and shortcomings as a strategy for cancer treatment.

Cisplatin prevents breast cancer metastasis through blocking early EMT and retards cancer growth together with paclitaxel

Cancer growth is usually accompanied by metastasis which kills most cancer patients. Here we aim to study the effect of cisplatin at different doses on breast cancer growth and metastasis.

Methods: We used cisplatin to treat breast cancer cells, then detected the migration of cells and the changes of epithelial-mesenchymal transition (EMT) markers by migration assay, Western blot, and immunofluorescent staining. Next, we analyzed the changes of RNA expression of genes by RNA-seq and confirmed the binding of activating transcription factor 3 (ATF3) to cytoskeleton related genes by ChIP-seq. Thereafter, we combined cisplatin and paclitaxel in a neoadjuvant setting to treat xenograft mouse models. Furthermore, we analyzed the association of disease prognosis with cytoskeletal genes and ATF3 by clinical data analysis.

Results: When administered at a higher dose (6 mg/kg), cisplatin inhibits both cancer growth and metastasis, yet with strong side effects, whereas a lower dose (2 mg/kg) cisplatin blocks cancer metastasis without obvious killing effects. Cisplatin inhibits cancer metastasis through blocking early steps of EMT. It antagonizes transforming growth factor beta (TGFβ) signaling through suppressing transcription of many genes involved in cytoskeleton reorganization and filopodia formation which occur early in EMT and are responsible for cancer metastasis. Mechanistically, TGFβ and fibronectin-1 (FN1) constitute a positive reciprocal regulation loop that is critical for activating TGFβ/SMAD3 signaling, which is repressed by cisplatin induced expression of ATF3. Furthermore, neoadjuvant administration of cisplatin at 2 mg/kg in conjunction with paclitaxel inhibits cancer growth and blocks metastasis without causing obvious side effects by inhibiting colonization of cancer cells in the target organs.

Conclusion: Thus, cisplatin prevents breast cancer metastasis through blocking early EMT, and the combination of cisplatin and paclitaxel represents a promising therapy for killing breast cancer and blocking tumor metastasis.

NOTCH1 activation compensates BRCA1 deficiency and promotes triple-negative breast cancer formation

BRCA1 mutation carriers have a higher risk of developing triple-negative breast cancer (TNBC), which is a refractory disease due to its non-responsiveness to current clinical targeted therapies. Using the Sleeping Beauty transposon system in Brca1-deficient mice, we identified 169 putative cancer drivers, among which Notch1 is a top candidate for accelerating TNBC by promoting the epithelial-mesenchymal transition (EMT) and regulating the cell cycle. Activation of NOTCH1 suppresses mitotic catastrophe caused by BRCA1 deficiency by restoring S/G2 and G2/M cell cycle checkpoints, which may through activation of ATR-CHK1 signalling pathway. Consistently, analysis of human breast cancer tissue demonstrates NOTCH1 is highly expressed in TNBCs, and the activated form of NOTCH1 correlates positively with increased phosphorylation of ATR. Additionally, we demonstrate that inhibition of the NOTCH1-ATR-CHK1 cascade together with cisplatin synergistically kills TNBC by targeting the cell cycle checkpoint, DNA damage and EMT, providing a potent clinical option for this fatal disease.

Unexpected therapeutic effects of cisplatin

Cisplatin is a widely used chemotherapeutic agent that is clinically approved to fight both carcinomas and sarcomas. It has relatively high efficiency in treating ovarian cancers and metastatic testicular cancers. It is generally accepted that the major mechanism of cisplatin anti-cancer action is DNA damage. However, cisplatin is also effective in metastatic cancers and should, therefore, affect slow-cycling cancer stem cells in some way. In this review, we focused on the alternative effects of cisplatin that can support a good therapeutic response. First, attention was paid to the effects of cisplatin at the cellular level such as changes in intracellular pH and cellular mechanical properties. Alternative cellular targets of cisplatin, and the effects of cisplatin on cancer cell metabolism and ER stress were also discussed. Furthermore, the impacts of cisplatin on the tumor microenvironment and in the whole organism context were reviewed. In this review, we try to reveal possible causes of the unexpected effectiveness of this anti-cancer drug.

Treatment of breast cancer with autophagy inhibitory microRNAs carried by AGO2-conjugated nanoparticles

Nanoparticle based gene delivery systems holds great promise. Superparamagnetic iron oxide nanoparticles (SPIONs) are being heavily investigated due to good biocompatibility and added diagnostic potential, rendering such nanoparticles theranostic. Yet, commonly used cationic coatings for efficient delivery of such anionic cargos, results in significant toxicity limiting translation of the technology to the clinic. Here, we describe a highly biocompatible, small and non-cationic SPION-based theranostic nanoparticles as novel gene therapy agents. We propose for the first-time, the usage of the microRNA machinery RISC complex component Argonaute 2 (AGO2) protein as a microRNA stabilizing agent and a delivery vehicle. In this study, AGO2 protein-conjugated, anti-HER2 antibody-linked and fluorophore-tagged SPION nanoparticles were developed (SP-AH nanoparticles) and used as a carrier for an autophagy inhibitory microRNA, MIR376B. These functionalized nanoparticles selectively delivered an effective amount of the microRNA into HER2-positive breast cancer cell lines in vitro and in a xenograft nude mice model of breast cancer in vivo, and successfully blocked autophagy. Furthermore, combination of the chemotherapy agent cisplatin with MIR376B-loaded SP-AH nanoparticles increased the efficacy of the anti-cancer treatment both in vitro in cells and in vivo in the nude mice. Therefore, we propose that AGO2 protein conjugated SPIONs are a new class of theranostic nanoparticles and can be efficiently used as innovative, non-cationic, non-toxic gene therapy tools for targeted therapy of cancer.

BRCA1 represses DNA replication initiation through antagonizing estrogen signaling and maintains genome stability in parallel with WEE1-MCM2 signaling during pregnancy

The mammary gland undergoes fast cell proliferation during early pregnancy, yet the mechanism to ensure genome integrity during this highly proliferative stage is largely unknown. We show that pregnancy triggers replicative stresses leading to genetic instability in mice carrying a mammary specific disruption of breast cancer associated gene-1 (BRCA1). The fast cell proliferation was correlated with enhanced expression of most genes encoding replisomes, which are positively regulated by estrogen/ERα signaling but negatively regulated by BRCA1. Our further analysis revealed two parallel signaling pathways, which are mediated by ATR-CHK1 and WEE1-MCM2 and are responsible for regulating DNA replication checkpoint. Upon DNA damage, BRCA1 deficiency markedly enhances DNA replication initiation and preferably impairs DNA replication checkpoint mediated by ATR and CHK1. Meanwhile, DNA damage also activates WEE1-MCM2 signaling, which inhibits DNA replication initiation and enables BRCA1-deficient cells to avoid further genomic instability. Finally, we demonstrated that overriding this defense by WEE1 inhibition in combination with cisplatin, which causes DNA damage, serves as a promising therapeutic approach for killing BRCA1-deficient cancer cells.

Identification of markers predictive for response to induction chemotherapy in patients with sinonasal undifferentiated carcinoma

OBJECTIVES

Sinonasal undifferentiated carcinoma (SNUC) is a rare, highly aggressive cancer. Despite aggressive multimodal therapy, its prognosis remains poor. Because of its locally advanced nature and high propensity for distant metastasis, we frequently use induction chemotherapy before definitive therapy in patients with SNUC. However, about 30% of patients do not respond to induction chemotherapy, and lack of response is associated with a poor survival rate. Therefore, in this study, we performed gene expression analysis of SNUC samples to identify prognostic markers for induction chemotherapy response.

MATERIALS AND METHODS

Formalin-fixed, paraffin-embedded SNUC tumor samples from previously untreated patients harvested before induction chemotherapy were used. Gene expression was performed using an oncology gene expression panel.

RESULTS

We identified 34 differentially expressed genes that distinguish the responders from the non-responders. Pathway analysis using these genes revealed alteration of multiple pathways between the two groups. Of these 34 genes, 24 distinguished between these two groups. Additionally, 16 gene pairs were associated with response to induction therapy.

CONCLUSION

We identified genes predictive of SNUC response to induction chemotherapy and pathways potentially associated with treatment outcome. This is the first report of identification of predictive biomarkers for response of SNUC to induction chemotherapy, and it may help us develop therapeutic strategies to improve the treatment outcomes of non-responders.

Leveraging the Role of the Metastatic Associated Protein Anterior Gradient Homologue 2 in Unfolded Protein Degradation: A Novel Therapeutic Biomarker for Cancer

Effective diagnostic, prognostic and therapeutic biomarkers can help in tracking disease progress, predict patients' survival, and considerably affect the drive for successful clinical management. The present review aims to determine how the metastatic-linked protein anterior gradient homologue 2 (AGR2) operates to affect cancer progression, and to identify associated potential diagnostic, prognostic and therapeutic biomarkers, particularly in central nervous system (CNS) tumors. Studies that show a high expression level of AGR2, and associate the protein expression with the resilience to chemotherapeutic treatments or with poor cancer survival, are reported. The primary protein structures of the seven variants of AGR2, including their functional domains, are summarized. Based on experiments in various biological models, this review shows an orchestra of multiple molecules that regulate AGR2 expression, including a feedback loop with p53. The AGR2-associated molecular functions and pathways including genomic integrity, proliferation, apoptosis, angiogenesis, adhesion, migration, stemness, and inflammation, are detailed. In addition, the mechanisms that can enable the rampant oncogenic effects of AGR2 are clarified. The different strategies used to therapeutically target AGR2-positive cancer cells are evaluated in light of the current evidence. Moreover, novel associated pathways and clinically relevant deregulated genes in AGR2 high CNS tumors are identified using a meta-analysis approach.

NVP-BEZ235 Attenuated Cell Proliferation and Migration in the Squamous Cell Carcinoma of Oral Cavities and p70S6K Inhibition Mimics its Effect

NVP-BEZ235 or BEZ235 is a dual inhibitor of adenosine triphosphate (ATP)-competitive phosphoinositide 3-kinase (PI3K)/mammalian-target-of-rapamycin (mTOR) and is promising for cancer treatment. Because it targets more than one downstream effector, a dual approach is promising for cancer treatment. The aim of this study was to evaluate the efficacy of NVP-BEZ235 in treating oral cavity squamous cell carcinoma (OSCC). Two human OSCC cell lines, SCC-4 and SCC-25, were used in this study. PI3K-AKT signaling, proliferation, and cell migratory and invasion capabilities of OSCC cells were examined. In NVP-BEZ235-treated SCC-4 and SCC-25 cells, the phosphorylation of 70-kDa ribosomal S6 kinase (p70S6K), but not mTOR, decreased within 24 h. NVP-BEZ235 inhibited OSCC-cell proliferation, migration, and invasion possibly by directly deregulating the phosphorylation of p70S6K. The phospho-p70S6K inhibitor mimicked the effects of NVP-BEZ235 for preventing proliferation and weakening the migratory and invasion abilities of SCC-4 and SCC-25 cells. This study further confirmed the effect of NVP-BEZ235 on OSCC cells and provided a new strategy for controlling the proliferation, migration, and invasion of OSCC cells using the phopho-p70S6K inhibitor.

Synergistic Antitumor Effect of Oligogalacturonides and Cisplatin on Human Lung Cancer A549 Cells

Cisplatin (DPP), a clinically potent antineoplastic agent, is limited by its severe adverse effects. The aim of this study was to investigate the effect of oligogalacturonides (OGA) and DDP on human lung cancer A549 cells. The combined use of OGA and DDP had a synergistic effect on the growth inhibition of A549 cells, changed the cell cycle distribution, and enhanced apoptotic response, especially in sequential combination treatment group of DDP 12 h + OGA 12 h. Western blot analyses showed that the combination treatment of OGA and DDP upregulated Bax, p53, and Caspase-3 and downregulated Bcl-2 proteins. More importantly, DDP-induced toxicity was attenuated by OGA and DDP combination treatment in normal HEK293 cells. Our data suggests that the combined use of OGA from natural sources and DDP could be an important new adjuvant therapy for lung cancer as well as offer important insights for reducing kidney toxicity of DDP and delaying the development of DDP resistance.

Wee1 Inhibitor AZD1775 Combined with Cisplatin Potentiates Anticancer Activity against Gastric Cancer by Increasing DNA Damage and Cell Apoptosis

Based on the mechanisms by which Wee1 inhibitor and cisplatin played their own role, a promising strategy of Wee1 inhibitor combined with cisplatin was proposed, which was investigated in gastric cancer (GC). Either Wee1 inhibitor AZD1775 or cisplatin alone had a certain inhibitory effect on in vitro cell proliferation; however, the inhibitory effect was more significant when AZD1775 combined with cisplatin in vitro and in vivo. The underlying mechanisms unveiled that the increased DNA damage indicated by increased γH2AX protein, as well as augmented cell apoptosis indicated by upregulated proapoptotic proteins, was responsible for the significant inhibitory effect of AZD1775 plus cisplatin. Moreover, compared to any single drug, in vitro cell migration and invasion abilities were further attenuated by AZD1775 combined with cisplatin. There were suggestive results that the potentiated cytotoxicity between AZD1775 and cisplatin deserved a deep exploration in the future.

NVP-BEZ235, a dual PI3K-mTOR inhibitor, suppresses the growth of FaDu hypopharyngeal squamous cell carcinoma and has a synergistic effect with Cisplatin

NVP-BEZ235 is a dual phosphoinositide 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) inhibitor. A dual approach targeting more than one downstream effector is a promising strategy for treating cancers. The aim of this study was to evaluate the effect of NVP-BEZ235 in treating FaDu hypopharyngeal squamous cell carcinoma (HSCC), either alone or in combination with cisplatin. We found mTOR expression was higher in patients with HSCC. In the in vitro study, treatment with NVP-BEZ235 alone attenuated cell proliferation and suppressed p-p70S6K and p-4E-BP1 expression in FaDu cells. When NVP-BEZ235 was combined with Cisplatin, apoptosis was induced more effectively than with either drug alone. In mice with a FaDu xenograft, cotreatment with NVP-BEZ235 and Cisplatin engendered synergistic effects and produced a greater antitumor response than did treatment with either drug alone. Resected tumor samples also showed decreased p-p70S6K expression. Collectively, these data demonstrate that NVP-BEZ235 inhibits HSCC growth through phospho-p70S6K suppression and has a synergistic effect with Cisplatin in treating HSCC. The data also provide a strategy for more effective HSCC treatment.

Ammonium tetrathiomolybdate treatment targets the copper transporter ATP7A and enhances sensitivity of breast cancer to cisplatin

Cisplatin is an effective breast cancer drug but resistance often develops over prolonged chemotherapy. Therefore, we performed a candidate approach RNAi screen in combination with cisplatin treatment to identify molecular pathways conferring survival advantages. The screen identified ATP7A as a therapeutic target. ATP7A is a copper ATPase transporter responsible for intercellular movement and sequestering of cisplatin. Pharmaceutical replacement for ATP7A by ammonium tetrathiomolybdate (TM) enhanced cisplatin treatment in breast cancer cells. Allograft and xenograft models in athymic nude mice treated with cisplatin/TM exhibited retarded tumor growth, reduced accumulation of cancer stem cells and decreased cell proliferation as compared to mono-treatment with cisplatin or TM. Cisplatin/TM treatment of cisplatin-resistant tumors reduced ATP7A protein levels, attenuated cisplatin sequestering by ATP7A, increased nuclear availability of cisplatin, and subsequently enhanced DNA damage and apoptosis. Microarray analysis of gene ontology pathways that responded uniquely to cisplatin/TM double treatment depicted changes in cell cycle regulation, specifically in the G1/S transition. These findings offer the potential to combat platinum-resistant tumors and sensitize patients to conventional breast cancer treatment by identifying and targeting the resistant tumors' unique molecular adaptations.

Alkaloids from Stephania venosa as Chemo-Sensitizers in SKOV3 Ovarian Cancer Cells via Akt/NF-κB Signaling

Crebanine (CN), tetrahydropalmatine (THP), O-methylbulbocapnine (OMBC) and N-methyl tetrahydropalmatine (NMTHP) are isoquinoline derived natural alkaloids isolated from tubers of Stephania venosa. We investigated chemo-sensitizing effects of these alkaloids in ovarian cancer cells and evaluated underlying molecular mechanisms involved in chemo-sensitivity. Detection of cell apoptosis was evaluated by using flow cytometry. Cell viability was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Chou-Talalay median effect principle was used to evaluate potential drug interactions. Protein analyses were performed on ovarian carcinoma cells using Western blotting upon treatment with anticancer drug and alkaloids. Aporphine alkaloids, such as CN and OMBC, enhanced cisplatin sensitivity in intrinsic cisplatin resistant SKOV3 cells, but not in cisplatin sensitive A2780 cells. Protoberberine alkaloids, such as THP and NMTHP, had no synergistic effect on cisplatin sensitivity in either cell line. Chemo-sensitizing effects of CN and OMBC in SKOV3 cells were mediated via activating apoptosis-induced cell death through caspase-3, -8 and cleaved poly ADP-ribose polymerase (PARP) and via inhibiting anti-apopotic and survival protein expression, such as Bcl-xL, Baculoviral IAP repeat-containing protein 3 (cIAP-2), survivin and interleukin (IL) -6. Cisplatin stimulated protein kinase B (Akt) and nuclear factor-kappaB (NF-κB) signaling pathways, but not mitogen-activated protein kinase (MAPK), activator protein 1 (AP-1) and signal transducer and activator of transcription 3 (STAT3) in SKOV3 cells. Akt/NF-κB signaling was blocked by CN and OMBC leading to increased sensitization to cisplatin. These findings demonstrate that CN and OMBC sensitizes SKOV3 cells to cisplatin via inhibition of Akt/NF-κB signaling and the down regulation of NF-κB mediated gene products. Our results suggest that alkaloids obtained from S. venosa could be used as chemo-sensitizers in ovarian cancer to sensitize and minimize the dose related toxicity of platinum-based chemotherapeutic drugs.

Potential therapeutic targets of triple-negative breast cancer based on its intrinsic subtype

Triple-negative breast cancer (TNBC) is an aggressive subgroup of human breast cancer, which is characterized as estrogen receptor (ER) negative, progesterone receptor (PR) negative, and human epidermal growth factor receptor 2 (HER2) negative. TNBC is the most difficult breast cancer subgroup to treat, due to its unresponsiveness to current clinical targeted therapies, high rate of recurrence, and poor prognosis. Thus, there is an urgent medical need to identify therapeutic targets and develop more effective stratified medicine for the treatment of TNBC. Here we review the potential therapeutic targets for TNBC based on its intrinsic subtype. We also review the aberrant activated signals found in different subgroups of TNBC, including androgen receptor (AR) and PI3K/AKT/mTOR, Notch, Wnt/β-catenin, Hedge-hog, and TGF-β signaling pathways, which play essential roles in multiple development stages of TNBC. The careful analysis of these signaling pathways and therapeutic targets would have significant impact on the drug development and clinical trials, leading to effective therapies for this deadly disease.

Inhibition of the PI3K/AKT/mTOR pathway activates autophagy and compensatory Ras/Raf/MEK/ERK signalling in prostate cancer

The PI3K/AKT/mTOR pathway is frequently activated in advanced prostate cancer, due to loss of the tumour suppressor PTEN, and is an important axis for drug development. We have assessed the molecular and functional consequences of pathway blockade by inhibiting AKT and mTOR kinases either in combination or as individual drug treatments. In established prostate cancer cell lines, a decrease in cell viability and in phospho-biomarker expression was observed. Although apoptosis was not induced, a G1 growth arrest was observed in PTEN null LNCaP cells, but not in BPH1 or PC3 cells. In contrast, when the AKT inhibitor AZD7328 was applied to patient-derived prostate cultures that retained expression of PTEN, activation of a compensatory Ras/MEK/ERK pathway was observed. Moreover, whilst autophagy was induced following treatment with AZD7328, cell viability was less affected in the patient-derived cultures than in cell lines. Surprisingly, treatment with a combination of both AZD7328 and two separate MEK1/2 inhibitors further enhanced phosphorylation of ERK1/2 in primary prostate cultures. However, it also induced irreversible growth arrest and senescence.

Ex vivo treatment of a patient-derived xenograft (PDX) of prostate cancer with a combination of AZD7328 and the mTOR inhibitor KU-0063794, significantly reduced tumour frequency upon re-engraftment of tumour cells.

The results demonstrate that single agent targeting of the PI3K/AKT/mTOR pathway triggers activation of the Ras/MEK/ERK compensatory pathway in near-patient samples. Therefore, blockade of one pathway is insufficient to treat prostate cancer in man.

WEE1 inhibition targets cell cycle checkpoints for triple negative breast cancers to overcome cisplatin resistance

Cisplatin is one of the most commonly used therapeutic drugs for cancer therapy, yet prolonged cisplatin treatment frequently results in drug resistance. To enhance therapeutic effect of cisplatin, we conducted a high throughput screening using a kinase library containing 704 kinases against triple negative breast cancer (TNBC) cells. We demonstrated that cisplatin activates ATR, CHK1 and WEE1, which shut down DNA replication and attenuate cisplatin induced-lethality. WEE1 inhibition sensitizes TNBCs and cisplatin resistant cancer cells to cisplatin-induced lethality, because it not only impairs DNA replication checkpoint more profoundly than inhibition of ATR or CHK1, but also defects G2-M cell cycle checkpoint. Finally, we demonstrated that combined cisplatin treatment and WEE1 inhibition synergistically inhibits xenograft cancer growth accompanied by markedly reduced expression of TNBC signature genes. Thus targeting DNA replication and G2-M cell cycle checkpoint simultaneously by cisplatin and WEE1 inhibition is promising for TNBCs treatment, and for overcoming their cisplatin resistance.

Development of novel PET probes targeting phosphatidylinositol 3-kinase (PI3K) in tumors

Phosphatidylinositol 3-kinase (PI3K) activity and protein expression levels are often increased in tumor regions. Since PI3K plays a crucial role in regulating cell growth and proliferation, inhibiting PI3K-dependent pathways could be a promising approach for cancer treatment. In clinical practice, however, evaluation of PI3K expression levels is limited to immunohistochemistry of patient samples, which requires invasive biopsies. Here we report the synthesis of three candidate compounds, FMTA-1, 2 and 3, and evaluate their capacity to detect PI3K expression levels with positron emission tomography (PET). Among the three candidates, FMTA-2 showed a lower IC50 value for PI3K. (18)F Radiolabeling of FMTA-2 to produce [(18)F]FMTA-2 was accomplished and its capacity for detecting PI3K expression levels was evaluated in vitro and in vivo. Cell uptake of [(18)F]FMTA-2 correlated well with cellular PI3K expression levels, and was suppressed by the ATP-competitive PI3K inhibitor ZSTK474. In an in vivo experiment using tumor-transplanted model mice, a higher signal-to-noise ratio (S/N) was seen with [(18)F]FMTA-2 in animals transplanted with DMS114 cells (expressing high PI3K levels) relative to DU145 cells (expressing low PI3K levels). However, in vivo pharmacokinetics of [(18)F]FMTA-2 was undesirable and the absolute amount of this compound that accumulated at the tumor region was low. To the best of our knowledge, this study represents the first trial of a PET tracer for detecting PI3K. Although further improvement of the probe is required prior to clinical application, these results should encourage future work.

The role of cytoskeleton and adhesion proteins in the resistance to photodynamic therapy. Possible therapeutic interventions

It is known that Photodynamic Therapy (PDT) induces changes in the cytoskeleton, the cell shape, and the adhesion properties of tumour cells. In addition, these targets have also been demonstrated to be involved in the development of PDT resistance. The reversal of PDT resistance by manipulating the cell adhesion process to substrata has been out of reach. Even though the existence of cell adhesion-mediated PDT resistance has not been reported so far, it cannot be ruled out. In addition to its impact on the apoptotic response to photodamage, the cytoskeleton alterations are thought to be associated with the processes of metastasis and invasion after PDT. In this review, we will address the impact of photodamage on the microfilament and microtubule cytoskeleton components and its regulators on PDT-treated cells as well as on cell adhesion. We will also summarise the impact of PDT on the surviving and resistant cells and their metastatic potential. Possible strategies aimed at taking advantage of the changes induced by PDT on actin, tubulin and cell adhesion proteins by targeting these molecules will also be discussed.