Sisi Wang

MiR-34a chemosensitizes bladder cancer cells to cisplatin treatment regardless of p53-Rb pathway status.

MiR‐34a is a downstream effector of p53 that has been shown to target several molecules associated with cell cycle and cell survival pathways. As alterations in these pathways are frequent in muscle invasive transitional cell carcinoma of the bladder (MI‐TCC), for example mutation or loss of p53 and Rb, the goal of this study was to determine whether manipulation of miR‐34a expression levels could abrogate the effect of these alterations and sensitize bladder cancer cells to chemotherapy. We demonstrate that transfection of T24, TCCSUP and 5637 with pre‐miR‐34a followed by cisplatin treatment results in a dramatic reduction in clonogenic potential and induction of senescence compared to treatment with cisplatin alone. Molecular analyses identified Cdk6 and sirtuin (SIRT)‐1 as being targeted by miR‐34a in MI‐TCC cells, however, inhibition of Cdk6 and SIRT‐1 was not as effective as pre‐miR‐34a in mediating chemosensitization. Analysis of 27 preneoadjuvant chemotherapy patient samples revealed many of the patients who subsequently did not respond to treatment (based on surgical resection postchemotherapy and 5‐year survival data) express lower levels of miR‐34a, however, a statistically significant difference between the responder and nonresponder groups was not observed (p = 0.1174). Analysis of eight sets of pre‐ and postneoadjuvant chemotherapy patient samples determined miR‐34a expression increased postchemotherapy in only two of the eight patients. The combined data indicate that elevation of miR‐34a expression levels before chemotherapy would be of benefit to MI‐TCC patients, particularly in a setting of low miR‐34a expression.

Targeting canine bladder transitional cell carcinoma with a human bladder cancer-specific ligand

ObjectiveTo determine if a human bladder cancer-specific peptide named PLZ4 can target canine bladder cancer cells.Experimental DesignThe binding of PLZ4 to five established canine invasive transitional cell carcinoma (TCC) cell lines and to normal canine bladder urothelial cells was determined using the whole cell binding assay and an affinitofluorescence assay. The WST-8 assay was performed to determine whether PLZ4 affected cell viability. In vivo tumor-specific homing/targeting property and biodistribution of PLZ4 was performed in a mouse xenograft model via tail vein injection and was confirmed with ex vivo imaging.ResultsPLZ4 exhibited high affinity and specific dose-dependent binding to canine bladder TCC cell lines, but not to normal canine urothelial cells. No significant changes in cell viability or proliferation were observed upon incubation with PLZ4. The in vivo and ex vivo optical imaging study showed that, when linked with the near-infrared fluorescent dye Cy5.5, PLZ4 substantially accumulated at the canine bladder cancer foci in the mouse xenograft model as compared to the control.Conclusions and Clinical RelevancePLZ4 can specifically bind to canine bladder cancer cells. This suggests that the preclinical studies of PLZ4 as a potential diagnostic and therapeutic agent can be performed in dogs with naturally occurring bladder cancer, and that PLZ4 can possibly be developed in the management of canine bladder cancer.

Gemcitabine causes minimal modulation of carboplatin-DNA monoadduct formation and repair in bladder cancer cells

We are developing a method to identify cellular resistance to carboplatin by using accelerator mass spectrometry to measure carboplatin-DNA adducts formed from drug microdoses (∼1/100th the therapeutic dose). Such an approach would be particularly useful if it is still valid in combination chemotherapy. We examined whether the addition of gemcitabine, another chemotherapeutic drug, could influence carboplatin-DNA adduct levels. There were no substantial differences in the levels of carboplatin-DNA adducts in cells upon exposure to the carboplatin/gemcitabine combination at various doses and schedules. These data demonstrate that microdosing is feasible for the characterization of carboplatin resistance when given in combination with gemcitabine.

Molecular Dissection of Induced Platinum Resistance through Functional and Gene Expression Analysis in a Cell Culture Model of Bladder Cancer

We report herein the development, functional and molecular characterization of an isogenic, paired bladder cancer cell culture model system for studying platinum drug resistance. The 5637 human bladder cancer cell line was cultured over ten months with stepwise increases in oxaliplatin concentration to generate a drug resistant 5637R sub cell line. The MTT assay was used to measure the cytotoxicity of several bladder cancer drugs. Liquid scintillation counting allowed quantification of cellular drug uptake and efflux of radiolabeled oxaliplatin and carboplatin. The impact of intracellular drug inactivation was assessed by chemical modulation of glutathione levels. Oxaliplatin- and carboplatin-DNA adduct formation and repair was measured using accelerator mass spectrometry. Resistance factors including apoptosis, growth factor signaling and others were assessed with RNAseq of both cell lines and included confirmation of selected transcripts by RT-PCR. Oxaliplatin, carboplatin, cisplatin and gemcitabine were significantly less cytotoxic to 5637R cells compared to the 5637 cells. In contrast, doxorubicin, methotrexate and vinblastine had no cell line dependent difference in cytotoxicity. Upon exposure to therapeutically relevant doses of oxaliplatin, 5637R cells had lower drug-DNA adduct levels than 5637 cells. This difference was partially accounted for by pre-DNA damage mechanisms such as drug uptake and intracellular inactivation by glutathione, as well as faster oxaliplatin-DNA adduct repair. In contrast, both cell lines had no significant differences in carboplatin cell uptake, efflux and drug-DNA adduct formation and repair, suggesting distinct resistance mechanisms for these two closely related drugs. The functional studies were augmented by RNAseq analysis, which demonstrated a significant change in expression of 83 transcripts, including 50 known genes and 22 novel transcripts. Most of the transcripts were not previously associated with bladder cancer chemoresistance. This model system and the associated phenotypic and genotypic data has the potential to identify some novel details of resistance mechanisms of clinical importance to bladder cancer.

A microdosing study to identify chemoresistance in bladder cancer.

356 Background: DNA adduct formation and incorporation of gemcitabine into genomic DNA are critical steps in cancer cell response to platinum (Pt) and gemcitabine chemotherapy, respectively. We hypothesize that levels of Pt-DNA adducts and gemcitabine in genomic DNA below a threshold are predictive of chemoresistance. Accelerator mass spectrometry (AMS) is an ultrasensitive method for measuring radiocarbon. By measuring 14C bound to DNA, AMS was used to quantify carboplatin-DNA damage and gemcitabine incorporation into DNA after mice or patients received nontoxic “microdoses” of 14C-labeled carboplatin or gemcitabine. Methods: Cancer cells and mice bearing tumor xenografts were treated with one microdose (1% of the therapeutic dose) or therapeutic dose of [14C]carboplatin or [14C]gemcitabine. Carboplatin-DNA adducts and gemcitabine incorporation in DNA were correlated with cell/tumor response to chemotherapy. In the Phase 0 trial, patients with advanced bladder or non-small cell lung cancer were treated w...

Abstract 905: Molecular dissection of platinum resistance through functional analysis

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA BACKGROUND: Platinum (Pt) agents (cisplatin, carboplatin and oxaliplatin) are active in many cancers including bladder cancer. Chemoresistance is the most common cause of treatment failure. This study is to determine the feasibility of using ultrasensitive accelerator mass spectrometry (AMS) to identify chemoresistance after cancer cells or patients are treated with one non-toxic microdose (1/100th of therapeutic dose) of Pt agents. The long-term goal is to identify chemoresistance before cancer patients receive toxic chemotherapy, and to determine the underlying resistance mechanisms to design personalized chemotherapy. METHODS: Cellular sensitivity to chemotherapeutic agents was determined by the MTT assay. Platinum-induced DNA adduct formation and repair of adducts was measured with AMS after cells were exposed 14C-labeled carboplatin and oxaliplatin. AMS quantifies the 14C label that is attached to genomic DNA when the 14C-labled drug forms adducts with DNA. Cell uptake and efflux was measured by liquid scintillation counting. Intracellular glutathione levels were measured by colorimetric analysis. RESULTS: Compared to the parental bladder cancer 5637 cells, chemoresistant 5637R cells are resistant to oxaliplatin (IC50: 2.45 µM versus 27.27 µM, p<0.0001), and cisplatin (0.59 µM versus 2.99 µM, p=0.049), carboplatin (24.34 µM versus 72.18 µM, p<0.0001), and gemcitabine (0.12 µM versus 1.44 µM, p=0.0015). Both 5637 and 5637R cells are still sensitive to other chemotherapeutic agents commonly used in treating bladder cancer, such as doxorubicin, methotrexate and vinblastine. Consistent with our hypothesis, chemoresistant 5637R cells have low oxaliplatin-induced DNA adduct levels than the parental 5637 cells (AUC of 943 versus 2,772 adducts per 109 nucleotide-hour for 5637, p=0.001). This low level of oxaliplatin-DNA adduct formation might be secondary to the pre-DNA damage mechanisms, such as decreased uptake (AUC of 4.42 versus 5.12 X 109 oxaliplatin molecules per cell for 5637, p=0.037) and increased intracellular inactivation of oxaliplatin by glutathione (53.91 versus 46.93 nmol/mg protein for 5637, p=0.003), plus increased repair of oxaliplatin-DNA adducts (3.48 versus 1.34 adducts per 108 nucleotides per hour for 5637, p=0.0004). We found the same correlation of low Pt-DNA adduct levels and chemoresistance in non-small cell lung (NSCLC) and breast cancer cell lines, and determined the same resistant mechanisms, such as cell uptake/efflux, intracellular inactivation and DNA repair. Carboplatin had partially different resistant mechanisms. CONCLUSION: Functional analysis of major resistant steps can identify some chemoresistance mechanisms that can potentially help design personalized chemotherapy to overcome resistance. This approach can be applied to several different cancer types. A Phase 0 microdosing clinical trial is currently going on in patients with NSCLC and bladder cancer. Citation Format: Amy W. Pan, Sisi Wang, Hongyong Zhang, Ruth Vinall, Tzu-yin Lin, Michael Malfatti, Maike Zimmermann, Tiffany Scharadin, Kenneth Turteltaub, Ralph de Vere White, Chong-xian Pan, Paul Henderson. Molecular dissection of platinum resistance through functional analysis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 905. doi:10.1158/1538-7445.AM2014-905

Abstract 1183: Phase 0 microdosing trial quantitating DNA adduct formation to identify platinum chemosensitivity: from bench to bedside.

Purpose: DNA adduct formation is a critical step in platinum(Pt)–induced cell death. The goal of this project is to measure carboplatin-DNA adducts after a single non-toxic microdose of [ 14 C]carboplatin, use this information to predict efficacy before cancer patients receive toxic chemotherapy and assess the underlying chemoresistance mechanisms, thus enhancing personalized therapy. Methods: Six non-small cell lung cancer (NSCLC) and six bladder cancer cell lines were treated with 1 μM (microdose) or 100 μM (therapeutic dose) carboplatin, but with equal amounts of [ 14 C]carboplatin. Carboplatin-DNA monoadduct levels were determined by measuring 14 C content in genomic DNA with accelerator mass spectrometry (AMS). Cellular sensitivity to carboplatin (IC 50 values) was correlated with drug-DNA adduct levels. To validate the in vitro findings, a pilot Phase 0 trial with microdosing [ 14 C]carboplatin was initiated to determine the recommended Phase II dose (RP2D) of [ 14 C]carboplatin for optimal measurement of DNA monoadducts and pharmacokinetics (PK) in lung and bladder cancer. PK and DNA monoadduct levels in peripheral blood mononuclear cells and tumor tissues were determined by liquid scintillation counting and AMS, respectively, validated with inductively coupled plasma mass spectrometry (ICP-MS), and correlated with tumor response to chemotherapy. Results: DNA monoadduct levels in cell lines induced by microdose and therapeutic concentrations of carboplatin were highly linearly proportional (r 2 = 0.95, p 2 = 0.80, p 14 C]carboplatin at 10 7 dpm/Kg with total carboplatin at 1% of therapeutic dose (area under curve of 6) was determined as the RP2D. No clinical toxicity was observed as a result of microdosing. The radiation exposure from 14 C was less than a chest X-ray per patient. DNA monoadduct levels and PK parameters of carboplatin at the microdose and therapeutic doses were highly correlated (p Conclusions: This novel microdosing approach predicts DNA monoadduct levels and PK of therapeutic carboplatin dosing; preliminary data suggest the feasibility of predicting chemosensitivity and the possibility of guiding personalized dosing. Citation Format: Chong-xian Pan, Sisi Wang, Miaoling He, Tao Li, Tzu-yin Lin, Hongyong Zhang, Michael Malfatti, David Gandara, Tianhong Li, Ken Yoneda, Joyce Lee, Marc Dall9Era, George Cimino, Ralph de Vere White, Kenneth Turteltaub, Paul Henderson. Phase 0 microdosing trial quantitating DNA adduct formation to identify platinum chemosensitivity: from bench to bedside. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1183. doi:10.1158/1538-7445.AM2013-1183

A phase 0 microdosing trial of an in vivo assay for predicting chemoresistance to platinum.

2578^ Background: As alkylating agents, platinum (Pt) analogs kill cancer cells mainly through induction of DNA damage. We hypothesize that low Pt-induced DNA damage is predictive of chemoresistance. We have developed a supersensitive accelerator mass spectrometry (AMS) method, with a sensitivity of 10-18~21 mole. AMS can detect carboplatin (carbo)-induced DNA damage in tissues after patients receive one subtoxic microdose (1/100th the therapeutic dose) of 14C-labeled carbo, and further allows mechanistic analysis of chemoresistance. METHODS A 2-stage accrual design was employed. In the first stage, a dose escalation/de-escalation strategy was used to determine toxicity and recommended Phase II dose (RP2D) of 14C-Carbo. Stage II was designed to determine if DNA damage levels induced by microdosing carbo correlate with chemoresistance, and to determine underlying resistance mechanisms. Patients with advanced non-small cell lung cancer or bladder cancer planning to receive Pt-based therapy are eligible. Primary endpoint is to determine and compare DNA damage levels induced by microdosing and therapeutic carbo. Secondary endpoints: pharmacokinetics (PK) of microdosing and therapeutic carbo, levels of tumoral DNA damage, and tumor response. RESULTS Stage I of the Phase 0 trial has been completed with an accrual of 5 patients. The Dose Level I of 107 dpm/kg of body weight is RP2D of 14C-carbo, which results in a desirable 14C signal-to-noise of 10~100 times background. This 14C level could be easily detected by AMS, but with minimal radiation exposure to patients (less than 1% that of an abdominal CT scan.). No acute toxicity was observed. Serum half life of carbo ranged from 1.30 to 1.58 hours-well within the reported range for the therapeutic carbo. DNA damage levels positively correlated with carbo half-life. Comparisons of the microdosing and therapeutic carbo PK, correlation of DNA damage and tumor response to subsequent chemotherapy, and the results of Stage II trial will be reported. CONCLUSIONS A Phase 0 trial as a platform to study Pt resistance can be feasibly conducted with one non-toxic microdose of 14C-labeled carbo using supersensitive AMS-based technology and has implications for personalized therapy.

Abstract 3522: A Phase 0 microdosing trial to identify chemoresistance: From bench to bedside

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC BACKGROUND: DNA damage is the critical step in cancer cell response to platinum (Pt) chemotherapy. We hypothesize that low levels of Pt-induced DNA damage are predictive of chemoresistance. Accelerator mass spectrometry (AMS) is an ultrasensitive method for measuring radiocarbon. By measuring 14C bound to DNA, AMS can detect carboplatin-induced DNA damage after patients receive one subtoxic microdose of 14C-labeled carboplatin. METHODS: Cancer cells and mice bearing tumor xenografts were treated with one microdose (1/100th of the therapeutic dose) or one therapeutic dose of [14C]carboplatin. Carboplatin-DNA adducts and other relevant parameters such as drug influx/efflux, intracellular drug inactivation, and repair of DNA damage, were measured and correlated with response to chemotherapy. RESULTS: AMS detected Pt-DNA damage when cancer cells and mice with tumor xenografts were exposed to one subtoxic microdose of [14C]carboplatin. The levels of microdose-induced DNA damage were linearly proportional to the DNA damage caused by the therapeutic drug dose (R2=0.92, p<0.001); and these levels of DNA damage correlated with chemoresistance. Low DNA damage predicts chemoresistance. Measuring drug uptake/efflux, intracellular inactivation and DNA repair allowed insight into some resistance mechanisms. A Phase 0 microdosing trial has been designed to study patients with non-small cell lung cancer or bladder cancer who are scheduled to receive Pt-based chemotherapy. One subtoxic microdose of 14C-carboplatin will be administered to these patients before biopsy. Pt-induced DNA damage and repair in left-over tumor biopsy specimens and other relevant parameters will be measured and correlated with the response and toxicity of chemotherapy. Molecular analysis of genes such as ERCC1 and RRM1 will be analyzed and compared with this Phase 0 results. CONCLUSION: The levels of DNA damage induced by nontoxic microdosing carboplatin can potentially predict chemoresistance in patients. A phase 0 microdosing trial is under the IRB review to identify chemoresistance and determine the underlying resistant mechanisms for personalized therapy before patients receive toxic Pt chemotherapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3522.