Comet assay measures of DNA damage are predictive of bladder cancer cell treatment sensitivity in vitro and outcome in vivo

Relevance of Comet Assay and Phosphorylated-Hsp90α in Cancer Patients' Peripheral Blood Leukocytes as Tools to Assess Cisplatin-based Chemotherapy Clinical Response and Disease Outcome

Cisplatin (cPt) is a commonly used treatment for solid tumors. The main target of its cytotoxicity is the DNA molecule, which makes the DNA damage response (DDR) crucial for cPt-based chemotherapy. Therefore, it is essential to identify biomarkers that can accurately predict the individual clinical response and prognosis. Our goal was to assess the usefulness of alkaline comet assay and immunocytochemical staining of phosphorylated Hsp90α (p-Hsp90α), γH2AX, and 53BP1 as predictive/prognostic markers. Pre-chemotherapy peripheral blood leukocytes were exposed to cPt in vitro and collected at 0, 24 (T24), and 48 (T48) hr post-drug removal. Healthy subjects were also included. Baseline DNA damage was elevated in cancer patients (variability between individuals was observed). After cPt, patients showed increased γH2AX foci/nucleus (T24 and T48). Both in healthy persons and patients, the nuclear p-Hsp90α and N/C (nuclear/cytoplasmic) ratio augmented (T24), decreasing at T48. Favorable clinical response was associated with high DNA damage and p-Hsp90α N/C ratio following cPt. For the first time, p-Hsp90α significance as a predictive marker is highlighted. Post-cPt-DNA damage was associated with longer disease-free survival and overall survival. Our findings indicate that comet assay and p-Hsp90α (a marker of DDR) would be promising prognostic/predictive tools in cP-treated cancer patients.

Comet-FISH analysis of urothelial cells. A screening opportunity for bladder cancer?

INTRODUCTION

Bladder cancer (BCa) is the most frequent cancer of the urinary tract, with more than 500,000 reported cases and nearly 200,000 related deaths yearly. Cystoscopy is the standard examination used for the initial diagnosis and follow-up of BCa in the noninvasive stage. However, the American Cancer Society does not include BCa screening in its list of recommended cancer screenings.

AREAS COVERED

Recently, several urine-based bladder tumor markers (UBBTMs) that identify genomic, transcriptomic, epigenetic, or protein alterations have been introduced, some of which have been approved by the Food and Drug Administration (FDA) to improve its diagnosis and surveillance. Several biomarkers have been found in the tissues and blood of individuals with BCa or predisposed to develop the disease, further enriching our information.

EXPERT OPINION

From a prevention perspective, alkaline Comet-FISH could be a valuable tool with broad potential for clinical application. Furthermore, a comet assay could be more beneficial for diagnosing and monitoring bladder cancer and determining individual susceptibility. Thus, we recommend further studies to understand the potential of this combined assay in the general population as a potential screening test and in patients initiated into the diagnostic process.

Genotoxicity study of 2-methoxyethanol and benzalkonium chloride through Comet assay using 3D cultured HepG2 cells

Though the key data in identifying carcinogenicity is experience in human, long-term carcinogenicity tests using experimental animals are more realistic. Because carcinogenicity tests require much time and cost, performing the test is minimized through pre-screening. Recently, as bioethics has been strengthened, it is required to minimize animal testing in screening tests as well as carcinogenicity tests. The replacement of the micronucleus assay in experimental animal is the beginning, and the ultimate goal is to replace the carcinogenicity test using experimental animals. The micronucleus assay and the comet assay in 3D culture system of human-derived cells is considered as the most applicable practical measures at this stage. This study was conducted to provide more diverse information in the evaluation of carcinogenicity by establishing the comet test method in a three-dimensional cell culture system. In this study, HepG2 cells were cultured for 4 days in hang-in drop method, and then cultured for 7 days on a low adhesion plate to prepare spheroids. The methods were confirmed by d-mannitol (negative control), ethylmethane sulfonate (positive control), and cyclophosphamide (positive control for metabolite). 2-methoxyethanol and benzalkonium chloride were selected as test substances. Though 2-methoxyethanol is positive in in vivo comet assay and in vitro mammalian chromosome aberration test, it is considered negative in the comprehensive genotoxicity evaluation based on negative in bacterial reverse mutation assay, in vitro mammalian cell gene mutation test and mammalian chromosome aberration test. Benzalkonium chloride has been questioned on carcinogenicity because it is a disinfectant ingredient that has become a social issue in Korea. As a result of the Comet assay for 2-methoxyethanol and benzalkonium chloride in the cultured HepG2 cell line, 2-methoxyethanol was evaluated as positive in the metabolic activation system, but benzalkonium chloride was evaluated as negative in both the presence and absence of the metabolic activation system. Therefore, in order to clarify the carcinogenic potential of 2-methoxyethanol, it is judged that additional studies based on mechanistic studies are needed.

In vitro assays for investigating the FLASH effect

FLASH radiotherapy is a novel technique that has been shown in numerous preclinical in vivo studies to have the potential to be the next important improvement in cancer treatment. However, the biological mechanisms responsible for the selective FLASH sparing effect of normal tissues are not yet known. An optimal translation of FLASH radiotherapy into the clinic would require a good understanding of the specific beam parameters that induces a FLASH effect, environmental conditions affecting the response, and the radiobiological mechanisms involved. Even though the FLASH effect has generally been considered as an in vivo effect, studies finding these answers would be difficult and ethically challenging to carry out solely in animals. Hence, suitable in vitro studies aimed towards finding these answers are needed. In this review, we describe and summarise several in vitro assays that have been used or could be used to finally elucidate the mechanisms behind the FLASH effect.

Theaflavin-3-gallate, a natural antagonist for Hsp90: In-silico and in-vitro approach

Poor prognosis and metastasis have been recognized as the major cause of breast cancer related deaths worldwide. Recent experimental evidence has shown that Hsp90, the prime chaperone, is overexpressed in many cancers and is responsible if reducing the 5-year survival rate of cancer patients. Therefore, targeted inhibition of Hsp90 may be a new and effective way to target cancer as well as enhancing therapeutic outcomes. In the present study, screening and stimulation of potential natural compounds result in the identification of theaflavin-3-gallate as a promising inhibitory compound of Hsp90. Further in-vitro validation of the cytotoxic effect of theaflavin-3-gallate in human breast carcinoma cell line MCF7 and normal cell line MCF10A revealed that theaflavin-3-gallate significantly inhibited the cell proliferation of MCF7 cells whereas no cytotoxic effect was observed on MCF10A cells. We also found that theaflavin-3-gallate significantly induced programmed cell death by arresting cells in the G2/M phase of the cell cycle. A significant decrease in cell migration and colony formation by theaflavin-3-gallate treatment was also observed in MCF7 cells. Furthermore, theaflavin-3-gallate significantly downregulated the mRNA expression patterns of the HSP90, MMP9, VEGFA, and SPP1 genes. Collectively, our results demonstrated theaflavin-3-gallate as a potential natural Hsp90 inhibitor that can be used to enhance the therapeutic efficacy of existing breast cancer therapies and improve overall survival of breast cancer patients.

Benefits of functional assays in personalized cancer medicine: more than just a proof-of-concept

As complex and heterogeneous diseases, cancers require a more tailored therapeutic management than most pathologies. Recent advances in anticancer drug development, including the immuno-oncology revolution, have been too often plagued by unsatisfying patient response rates and survivals. In reaction to this, cancer care has fully transitioned to the “personalized medicine” concept. Numerous tools are now available tools to better adapt treatments to the profile of each patient. They encompass a large array of diagnostic assays, based on biomarkers relevant to targetable molecular pathways. As a subfamily of such so-called companion diagnostics, chemosensitivity and resistance assays represent an attractive, yet insufficiently understood, approach to individualize treatments. They rely on the assessment of a composite biomarker, the ex vivo functional response of cancer cells to drugs, to predict a patient's outcome. Systemic treatments, such as chemotherapies, as well as targeted treatments, whose efficacy cannot be fully predicted yet by other diagnostic tests, may be assessed through these means. The results can provide helpful information to assist clinicians in their decision-making process. We explore here the most advanced functional assays across oncology indications, with an emphasis on tests already displaying a convincing clinical demonstration. We then recapitulate the main technical obstacles faced by researchers and clinicians to produce more accurate, and thus more predictive, models and the recent advances that have been developed to circumvent them. Finally, we summarize the regulatory and quality frameworks surrounding functional assays to ensure their safe and performant clinical implementation. Functional assays are valuable in vitro diagnostic tools that already stand beyond the “proof-of-concept” stage. Clinical studies show they have a major role to play by themselves but also in conjunction with molecular diagnostics. They now need a final lift to fully integrate the common armament used against cancers, and thus make their way into the clinical routine.

MEK Inhibitor Augments Antitumor Activity of B7-H3-Redirected Bispecific Antibody

Targeting cancer antigens by T cell-engaging bispecific antibody (BiAb) or chimeric antigen receptor T cell therapy has achieved successes in hematological cancers, but attempts to use it to fight solid cancers have been disappointing, in part due to antigen escape. MEK inhibitor had limited activity as a single agent, but enhanced antitumor activity when combined with other therapies, such as targeted drugs or immunotherapy agents. This study aimed to analyze the expression of B7-H3 in non-small-cell lung cancer (NSCLC) and bladder cancer (BC) and to evaluate the combinatorial antitumor effect of B7-H3 × CD3 BiAb with MEK inhibitor trametinib. We found B7-H3 was highly expressed in NSCLC and BC compared with normal samples and its increased expression was associated with poor prognosis. Treatment with trametinib alone could induce apoptosis in tumor cell, while has no effect on T cell proliferation, and a noticeable elevation of B7-H3 expression in tumor cells was also observed following treatment. B7-H3 × CD3 BiAb specifically and efficiently redirected their cytotoxicity against B7-H3 overexpressing tumor cells both in vitro and in xenograft mouse models. While trametinib treatment alone affected tumor growth, the combined therapy increased T cell infiltration and significantly suppressed tumor growth. Together, these data suggest that combination therapy with B7-H3 × CD3 BiAb and MEK inhibitor may serve as a new therapeutic strategy in the future clinical practice for the treatment of NSCLC and BC.

DNA damage measured in blood cells predicts overall and progression-free survival in germ cell tumour patients

Germ cell tumour (GCT) patients who fail to respond to chemotherapy or who relapse have a poor prognosis. Timely and accurately stratifying such patients could optimise their therapy. We identified endogenous DNA damage levels as a prognostic marker for progression-free (PFS) and overall (OS) survival in chemotherapy-naïve GCT patients. In the present study, we have extended our previous results and reviewed the prognostic power of DNA damage level in GCTs. Endogenous DNA damage levels were measured with the comet assay. Receiver operator characteristic analysis was applied to determine the optimal cut-off value and to evaluate its prognostic accuracy. PFS and OS were estimated by the Kaplan-Meier method and compared using the log-rank test. Hazard ratio (HR) estimates were calculated by Cox regression analysis. A cut-off value of 6.34 provided the highest sensitivity and specificity, with area under curve values of 0.813 and 0.814 for disease progression and mortality, respectively. A % DNA in tail > 6.34 was significantly associated with shorter PFS (HR = 9.54, 95 % confidence interval [CI]: 3.43-26.55, p < 0.001) and OS (HR = 14.62, 95 % CI: 3.14-67.95, p = 0.001) by univariate analysis. The prognostic value of DNA damage measurement was confirmed by multivariate models (HR = 6.45, 95 % CI: 2.22-18.75, p = 0.001 for PFS and HR = 9.40, 95 % CI: 1.70-52.09, p = 0.010 for OS), when HR was adjusted for relevant clinical categories. The added prognostic value of DNA damage in combination with International Germ Cell Cancer Collaborative Group (IGCCCG) risk groups has been revealed. Endogenous DNA damage is an independent prognosticator for PFS and OS in GCT patients and its clinical use, particularly in combination with IGCCCG risk groups, may help in stratifying these patients.

Evaluation of the Major Steps in the Conventional Protocol for the Alkaline Comet Assay

Single cell gel electrophoresis, also known as the comet assay, has become a widespread DNA damage assessment tool due to its sensitivity, adaptability, low cost, ease of use, and reliability. Despite these benefits, this assay has shortcomings, such as long assay running time, the manipulation of multiple slides, individually, through numerous process steps, the challenge of working in a darkened environment, and reportedly considerable inter- and intra-laboratory variation. All researchers typically perform the comet assay based upon a common core approach; however, it appears that some steps in this core have little proven basis, and may exist, partly, out of convenience, or dogma. The aim of this study was to critically re-evaluate key steps in the comet assay, using our laboratory's protocol as a model, firstly to understand the scientific basis for why certain steps in the protocol are performed in a particular manner, and secondly to simplify the assay, and decrease the cost and run time. Here, the shelf life of the lysis and neutralization buffers, the effect of temperature and incubation period during the lysis step, the necessity for drying the slides between the electrophoresis and staining step, and the need to perform the sample workup and electrophoresis steps under subdued light were all evaluated.

Targeting immunotherapy for bladder cancer by using anti-CD3 × CD155 bispecific antibody

To investigate whether CD155 is an attractive target for T cell-mediated immunotherapy against human bladder cancer, we examined the novel bispecific antibody anti-CD3 x anti-CD155 (CD155Bi-Ab) for its ability to redirect activated T cells (ATCs) to target bladder cancer cells was examined. Expression of CD155 was detected by flow cytometry on the surface of bladder cancer cells, including T24 and Pumc-91 cells, and their chemotherapeutic drug-resistant counterparts. ATCs generated from healthy donors were stimulated with anti-CD3 monoclonal antibody, anti-CD28 monoclonal antibody and interleukin-2 (IL-2) for 14 days. The cytotoxic activity of ATCs armed with CD155Bi-Ab against bladder cancer cells was detected by LDH and luciferase quantitative assay. Furthermore, ATCs generated from bladder cancer patients were also armed with CD155Bi-Ab to verity the cell killing by the same methods. In contrast to unarmed ATCs, CD155Bi-armed ATCs against bladder cancer cells were increased cytotoxic activity at effector/target (E/T) ratios of 5:1, 10:1, and 20:1, with more IFN-γ, TNF-α secreting. It is worth noting that in spite of the presence of immunosuppression in bladder cancer patients and the drug resistance in chemotherapeutic drug-resistant cancer cell lines, not only the anti-tumor effect of CD155Bi-armed ATCs generated from bladder cancer patients still showed significantly but only higher level of activation marker CD69 was expressed. Taken together, our results suggest that CD155 is an effective target for the CD155-positive bladder cancer. And CD155Bi-Ab-armed ATCs are promisingly to provide a novel strategy for current CD155-positive bladder cancer therapy.

Knockdown of Annexin A1 Enhances Radioresistance and Inhibits Apoptosis in Nasopharyngeal Carcinoma

Radiotherapy is the primary treatment for nasopharyngeal carcinoma while radioresistance can hinder efficient treatment. To explore the role of annexin A1 and its potential mechanisms in radioresistance of nasopharyngeal carcinoma, human nasopharyngeal carcinoma cell line CNE2-sh annexin A1 (knockdown of annexin A1) and the control cell line CNE2-pLKO.1 were constituted and CNE2-sh annexin A1 xenograft mouse model was generated. The effect of annexin A1 knockdown on the growth of xenograft tumor after irradiation and radiation-induced DNA damage and repair was analyzed. The results of immunohistochemistry assays and Western blotting showed that the level of annexin A1 was significantly downregulated in the radioresistant nasopharyngeal carcinoma tissues or cell line compared to the radiosensitive nasopharyngeal carcinoma tissues or cell line. Knockdown of annexin A1 significantly promoted CNE2-sh annexin A1 xenograft tumor growth compared to the control groups after irradiation. Moreover, the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assays revealed that knockdown of annexin A1 significantly inhibited apoptosis in vivo compared to the control groups. We assessed the intracellular reactive oxygen species levels and the extent of radiation-induced DNA damage and repair using reactive oxygen species assay, comet assays, and immunohistochemistry assay. The results showed that knockdown of annexin A1 remarkedly reduced the intracellular reactive oxygen species levels, level of DNA double-strand breaks, and the phosphorylation level of H2AX and increased the accumulation of DNA-dependent protein kinase in nasopharyngeal carcinoma cells after irradiation. The findings suggest that knockdown of annexin A1 inhibits DNA damage via decreasing the generation of intracellular reactive oxygen species and the formation of γ-H2AX and promotes DNA repair via increasing DNA-dependent protein kinase activity and therefore improves the radioresistance in nasopharyngeal carcinoma cells. Together, our findings suggest that knockdown of annexin A1 promotes radioresistance in nasopharyngeal carcinoma and provides insights into therapeutic targets for nasopharyngeal carcinoma radiotherapy.

Inhibition of EZH2 induces NK cell-mediated differentiation and death in muscle-invasive bladder cancer

Lysine-specific demethylase 6A (KDM6A) and members of the Switch/Sucrose Non-Fermentable (SWI/SNF) family are known to counteract the activity of Enhancer of Zeste Homolog 2 (EZH2), which is often overexpressed and is associated with poor prognosis in muscle-invasive bladder cancer. Here we provide evidence that alterations in chromatin modifying enzymes, including KDM6A and members of the SWI/SNF complex, are frequent in muscle-invasive bladder cancer. We exploit the loss of function mutations in KDM6A and SWI/SNF complex to make bladder cancer cells susceptible to EZH2-based epigenetic therapy that activates an immune response to drive tumor cell differentiation and death. We reveal a novel mechanism of action of EZH2 inhibition, alone and in combination with cisplatin, which induces immune signaling with the largest changes observed in interferon gamma (IFN-γ). This upregulation is a result of activated natural killer (NK) signaling as demonstrated by the increase in NK cell-associated genes MIP-1α, ICAM1, ICAM2, and CD86 in xenografts treated with EZH2 inhibitors. Conversely, EZH2 inhibition results in decreased expression of pluripotency markers, ALDH2 and CK5, and increased cell death. Our results reveal a novel sensitivity of muscle-invasive bladder cancer cells with KMD6A and SWI/SNF mutations to EZH2 inhibition alone and in combination with cisplatin. This sensitivity is mediated through increased NK cell-related signaling resulting in tumor cell differentiation and cell death.

Combined pretreatment with 18F-FDG PET/CT and Comet assay guides the concurrent chemoradiotherapy of locally advanced cervical cancer: study protocol for a randomized controlled trial

Background

Cisplatin-based chemoradiation is the standard of care for patients with locally advanced cervical cancer. Nevertheless, an increasing number of radio-resistant tumors still recur.

Methods and design

Three hundred cervical cancer patients with FIGO stages IB2–IVA and no para-aortic lymphadenopathy (> 10 mm) will be enrolled. All patients will be randomly divided into four arms to receive either (1) intensity modulated radiation therapy (IMRT), (2) RapidArc, (3) positron emission tomography/computed tomography (PET/CT) with F-18 fluorodeoxyglucose (FDG), or (4) Comet assay-guided IMRT, PET/CT, and Comet assay-guided RapidArc. All patients will receive definitive radiotherapy consisting of external beam whole pelvic radiation therapy and high-dose rate intracavitary brachytherapy. Cisplatin 30 mg/m² weekly will be administered concurrently for five courses. Two to four cycles of TP (Taxol 135 mg/m², D1, and DDP 75 mg/m², D1–3) sequential chemotherapy will be performed according to MRI or PET/CT after cisplatin-based chemoradiation. The primary outcome measure is progression-free survival, and the second outcome measures are overall survival and time to progression.

Discussion

RapidArc has an obvious advantage in improving the degree of target coverage, improving organs at risk, sparing healthy tissue, and significantly reducing the treatment time. FDG-PET/CT can increase the agreement between biopsies and delineated tumor volume and has the potential to positively impact the course of treatment. The Comet assay is attractive as a potential clinical test of tumor radiosensitivity. During radiotherapy, accurately defining disease areas is critical to avoid the unnecessary irradiation of normal tissue. Based on FDG-PET/CT and Comet assay, higher doses can be safely delivered to accurate tumor volumes, while the doses to the bladder and rectum are relatively low.

Trial registration

ClinicalTrials.gov Protocol Registration and Results System Receipt Release Date: May 21, 2017 – Retrospectively registered. NCT03163979.

The association between micronucleus, nucleoplasmic bridges, and nuclear buds frequency and the degree of uterine cervical lesions

BACKGROUND AND AIM

The loss of genomic stability plays an important role in carcinogenesis. Therefore, it is imperative to use certain biomarkers of DNA damage due to genomic instability in order to predict cancer risk. The aim of this study was the evaluation of genomic instability in patients with cervical lesions.

MATERIALS AND METHODS

We investigated the genetic damages in 80 subjects: 40 patients with high-grade squamous intraepithelial lesions (HSIL), 20 patients with invasive squamous cervical cancer (SCC) and 20 healthy women with a biomarker in two different tissues; the micronucleus (MN) test in peripheral blood lymphocytes (PBL), and in buccal exfoliated cells (BEC). This study also examined the frequency of other nuclear anomalies such as nucleoplasmic bridges (NPBs) and nuclear bunds (NBUDs) in PBL.

RESULTS

The frequency of MN in BEC, MN in PBL, NPB in PBL and NBUD in PBL were significantly higher (p < 0.001), in patients compared to controls. The DNA damages in BEC and PBL were correlated positively with histological grade of cervical lesions.

CONCLUSION

Although larger studies are needed, our data support the predictive value of MN, NPB and NBUD as biomarkers of genomic instability for evaluation of risk level of cancer diseases.

TPX2-p53-GLIPR1 regulatory circuitry in cell proliferation, invasion, and tumor growth of bladder cancer

The targeting protein for Xenopus kinesin-like protein 2 (TPX2) is associated with the metastasis and prognosis of bladder cancer. p53 is closely related to the progression of bladder cancer. Human glioma pathogenesis-related protein 1 (GLIPR1) is a p53 target gene with antitumor activity. This study aims to explore the interplay between TPX2, p53, and GLIPR1 and its correlation with cell proliferation, invasion, and tumor growth in bladder cancer. Here, Western blot and qRT-PCR analysis revealed that TPX2 at both mRNA and protein levels was up-regulated in bladder carcinoma tissues compared to their paired adjacent normal tissues. Additionally, tissues expressing high TPX2 level exhibited high p53 level and low GLIPR1 level. The expressions of TPX2 and p53 in non-muscle-invasive bladder cancer cells (KK47 and RT4) were lower than those in muscle-invasive bladder cancer cells (T24, 5637, and UM-UC-3), while GLIPR1 showed the converse expression pattern. Further investigation revealed that TPX2 activated the synthesis of p53; and GLIPR1 is up-regulated by wild-type (wt)-p53 but not affected by mutated p53; Additionally, GLIPR1 inhibited TPX2. These data suggested a TPX2-p53-GLIPR1 regulatory circuitry. Meanwhile, TPX2 overexpression promoted while overexpression of GLIPR1 or p53 inhibited bladder cancer growth. Interestingly, in T24 cells with mutated p53, p53 silence suppressed bladder cancer growth. This study identified a novel TPX2-p53-GLIPR1 regulatory circuitry which modulated cell proliferation, migration, invasion, and tumorigenicity of bladder cancer. Our findings provide new insight into underlying mechanisms of tumorigenesis and novel therapeutic options in bladder cancer.

Dynamic In Vivo Profiling of DNA Damage and Repair after Radiotherapy Using Canine Patients as a Model

Time resolved data of DNA damage and repair after radiotherapy elucidates the relation between damage, repair, and cell survival. While well characterized in vitro, little is known about the time-course of DNA damage response in tumors sampled from individual patients. Kinetics of DNA damage after radiotherapy was assessed in eight dogs using repeated in vivo samples of tumor and co-irradiated normal tissue analyzed with comet assay and phosphorylated H2AX (γH2AX) immunohistochemistry. In vivo results were then compared (in silico) with a dynamic mathematical model for DNA damage formation and repair. Maximum %DNA in tail was observed at 15–60 min after irradiation, with a rapid decrease. Time-courses of γH2AX-foci paralleled these findings with a small time delay and were not influenced by covariates. The evolutionary parameter search based on %DNA in tail revealed a good fit of the DNA repair model to in vivo data for pooled sarcoma time-courses, but fits for individual sarcoma time-courses suffer from the heterogeneous nature of the in vivo data. It was possible to follow dynamics of comet tail intensity and γH2AX-foci during a course of radiation using a minimally invasive approach. DNA repair can be quantitatively investigated as time-courses of individual patients by integrating this resulting data into a dynamic mathematical model.

New insight for metformin against bladder cancer

International Agency for Research on Cancer (IARC) estimated that bladder cancer is the ninth most common cancer in the world, with 430,000 new cases and 165,000 deaths in 2012. Bladder cancer represents the fourth most common cancer in men and ninth most common cancer in women. It is the second most prevalent cancer in men 60 years of age or older in United States. Looking further down, continuing advancements in cancer research could potentially offer more choices for clinician and patient with longer survival and better quality of life. Although, bladder cancer represents an ideal tumor model to test and apply cancer prevention strategies; there are limited studies about application of metformin in the management of bladder cancer. Here, I will shed light on the proposed mechanisms of anti-carcinogenic effects of metformin and cohort of these mechanisms with the novel application of metformin as therapy of bladder cancer.

DNA damage response in patients with pediatric Acute Lymphoid Leukemia during induction therapy

Predicting the individual response to chemotherapy is a crucial challenge in cancer treatment. DNA damage caused by antitumor therapies evokes different repair mechanisms responses, such as Nucleotide Excision Repair (NER), whose components are being studied as prognosis biomarkers and target therapies. However, few reports have addressed DNA damages in pediatric Acute Lymphoid Leukemia (ALL). Hence, we conducted an observational follow-up study with pediatric patients to assess DNA damage (by Comet Assay) and gene expression from NER pathway during chemotherapy induction. Bone marrow samples from diagnosis, 15th(D15) and 35th (D35) days of the treatment were collected from 28 patients with ALL. There was no increase in damage index. However, there was a reduction of cells with low damages on D35 compared with diagnosis. NER pathway expression remained the same, however, in a single patient, a significant decrease was observed, maybe due to silencing or downregulation of repair pathways. DNA damage levels and repair may influence the clinical outcome, being involved in drug resistance and risk of relapse. In pediatric ALL, we analyzed for the first time DNA damage and repair behavior in BM samples. Monitoring patient's outcomes will help to access the implication of our findings in survival and relapse rates.

Phase I study of LY2603618, a CHK1 inhibitor, in combination with gemcitabine in Japanese patients with solid tumors

This phase I trial evaluated LY2603618, a selective inhibitor of the DNA damage checkpoint kinase 1, in combination with gemcitabine. Japanese patients with advanced solid tumors were enrolled. All patients received gemcitabine (1000 mg/m on days 1, 8, and 15 every 28 days) and either 170 mg (cohort 1) or 230 mg (cohort 2) of LY2603618. The primary objective was assessment of safety/tolerability. Pharmacokinetic/pharmacodynamic marker profiles were secondary objectives. Of the 17 patients enrolled, dose-limiting toxicities were observed in one patient in cohort 1 (n=7) and in two patients in cohort 2 (n=10). The most common grade 3 or more drug-related treatment-emergent adverse events were hematological. Three patients discontinued because of adverse events. Dose-dependent decreases in LY2603618 exposure were observed, but the LY2603618 pharmacokinetics at each dose were consistent within and between cycles and did not influence gemcitabine pharmacokinetics. Circulating plasma DNA decreased from baseline in all four patients who achieved a partial response. Administration of 170 or 230 mg of LY2603618 following a standard dose of gemcitabine showed acceptable safety and tolerability in Japanese patients with solid tumors.

Anthocyans as tertiary chemopreventive agents in bladder cancer: anti-oxidant mechanisms and interaction with mitomycin C

Bladder cancer is associated with high rates of recurrence making tertiary chemoprevention an attractive intervention strategy. Anthocyanins have been shown to possess chemopreventive properties and are detectable in urine after oral ingestion, with higher concentrations achievable via intravesical administration alongside current chemotherapeutic regimens. Yet their apparent ability to protect against certain DNA damage may in turn interfere with cancer treatments. Our aim was therefore to determine the potential of anthocyanins as chemopreventive agents in bladder cancer, their mode of action and effects, both alone and in combination with mitomycin C (MMC). In this study we showed that mirtoselect, a standardised mixture of anthocyanins, possesses significant anti-proliferative activity, causing growth inhibition and apoptosis in bladder cancer cell lines. The anti-oxidative potential of mirtoselect was examined and revealed significantly fewer H2O2-induced DNA strand breaks, as well as oxidised DNA bases in pre-treated cells. In contrast, endogenous levels of oxidised DNA bases were unaltered. Investigations into the possible protective mechanisms associated with these anti-oxidant properties revealed that mirtoselect chelates metal ions. In mirtoselect/MMC combination studies, no adverse effects on measures of DNA damage were observed compared to treatment with MMC alone and there was evidence of enhanced cell death. Consistent with this, significantly more DNA crosslinks were formed in cells treated with the combination. These results show that mirtoselect exerts effects consistent with chemopreventive properties in bladder cancer cell lines and most importantly does so without adversely affecting the effects of drugs used in current treatment regimens. We also provide evidence that mirtoselect's anti-oxidative mechanism of action is via metal ion chelation. Overall these results suggest that mirtoselect could be an effective chemopreventive agent in bladder cancer and provides the necessary pre-clinical data for future in vivo animal studies and clinical trials.