Abstract 3683: Activation of purine anabolism creates a therapeutic vulnerability in hepatocellular carcinoma via m6A-mediated epitranscriptomic regulation

Introduction Purines are building blocks for genomics and the abundance of purine nucleotides is controlled by purine synthesis and purine degradation. Imbalance of purine nucleotide pool in tumors has been shown, but how synthesis and degradation of purine integrates in tumors has not been well characterized. Hepatocellular carcinoma (HCC) is the most common liver cancer with a high mortality rate and limited treatments. Aberrant purine metabolism was observed in HCC, but the functional status of global purine metabolism in HCC and how that drive HCC fitness and therapeutic response remain unclear. Method HCC-specific purine metabolic changes were identified from the transcriptomic and metabolic data of tumor and paired non-tumor liver tissues obtained from 62 HCC patients from Thailand (discovery cohort) and validated in an additional 672 HCC with different race/ethnicities and etiologies. Correlation analysis of purine metabolic alteration and tumor-associated genomic, transcriptome and metabolome were conducted. The impacts of purine metabolism on HCC survival and therapeutic vulnerability were investigated. Biological functions of purine metabolic alterations were assessed in vitro and in vivo on multiple HCC cell lines. Results Using multi-omics integrative analyses, we found a tumor-specific activation of purine anabolism, induced by upregulation of purine de novo biosynthesis and inhibition of purine degradation, in HCC. A high purine anabolic status was associated with dysregulation of the DNA damage repairing (DDR) machinery in HCC, accompanied by unique somatic mutational signatures linked to patient prognosis. By examining drug responses to 180 molecular targeted agents in HCC cells, we found that increasing purine anabolism induced a therapeutic vulnerability of HCC to DDR targeting agents. Mechanistically, we found that excessive purine metabolites induced N6-methyladenosine (m6A) modification on DTL, a DDB1 cullin4 associated factor, thereby delaying the degradation of DTL mRNA transcriptomic remodeling of the DDR machinery and tumor fitness. Experimentally, we demonstrated that suppressing purine anabolism or exposing to DDR targeting agent, such as berzosertib, inhibited the growth of HCCs with high purine anabolism in vitro and in vivo. Conclusion Our study suggests that targeting purine anabolism or DDR may represent as attractive strategies in patients with high purine anabolic HCCs, and purine anabolic status could be a valuable biomarker to allocate systemic treatments for patients with advanced HCC.

Citation Format: Man-Hsin Hung, Ching Wen Chang, Kathy Cheng Wang, Jittiporn Chaisaingmongkol, Mathuros Ruchirawat, Tim F. Greten, Xin Wei Wang. Activation of purine anabolism creates a therapeutic vulnerability in hepatocellular carcinoma via m6A-mediated epitranscriptomic regulation. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3683.

TD-92, a novel erlotinib derivative, depletes tumor-associated macrophages in non-small cell lung cancer via down-regulation of CSF-1R and enhances the anti-tumor effects of anti-PD-1

Recent advances in immune checkpoint inhibition, which augment T-cell immune responses, have highlighted the potential of exploiting one's immune system to combat cancer. However, only a relatively small number of non-small cell lung cancer (NSCLC) patients benefit from immune checkpoint blockade due to the immunosuppressive tumor microenvironment. Therefore, combination immunotherapies are now being developed to achieve maximal therapeutic benefits. In this study, we assessed whether a novel erlotinib derivative, TD-92, which possesses anti-tumor effects across several cancer cell lines, could enhance anti-PD-1 treatment. Our results demonstrated that the combined treatment of anti-PD-1 and TD-92 resulted in a potent anti-tumor response in a Lewis lung carcinoma cancer model, as evidenced by the reduced tumor growth and increased survival. Analysis of immune cell population counts revealed that TD-92 reduced the number of pro-tumorigenic CD11b⁺ F4/80⁺ tumor-associated macrophages, without significantly affecting the total numbers of other major immunocytes. Further experiments showed that TD-92 induced a marked decline in colony stimulating factor 1 receptor (CSF-1R) expression in macrophage cell lines. The results also suggested that c-Cbl-mediated proteasome degradation was involved in TD-92-mediated CSF-1R downregulation. Our data paves the way for the development of additional combination immunotherapies for NSCLC patients.

Palbociclib enhances radiosensitivity of hepatocellular carcinoma and cholangiocarcinoma via inhibiting ataxia telangiectasia-mutated kinase-mediated DNA damage response

AIM

Palbociclib is an oral cyclin-dependent kinase 4/6 inhibitor, which is efficacious in treating breast cancer. Currently, there are numerous active clinical trials testing palbociclib alone or in combination with other medications for treating various types of malignancies. Here, we evaluated the anti-cancer effect of palbociclib in combination with radiation therapy (RT) for treating human hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) and addressed the molecular mechanism behind the combination therapy.

METHODS

Immunofluorescence staining of γH2AX or 53BP1 was used to determine the effect of palbociclib on double-strand break (DSB) repair. Clonogenic assays, sphere formation and cell death ELISA were performed to study the sensitising effect of palbociclib on radiation-induced cytotoxicity. Signal alteration in DSB repair pathways was examined by Western blot analysis. Finally, we evaluated the in vivo anti-cancer activity and the associated molecular events of the combination therapy in a preclinical HCC xenograft model.

RESULTS

Palbociclib affected the kinetics of DNA repair and enhanced the radiation sensitivity of HCC and CCA cells. Importantly, we found that palbociclib inhibits ataxia telangiectasia-mutated (ATM) kinase, the key upstream kinase responding to RT-induced DSBs. Furthermore, we showed that the inhibitory effect of palbociclib on RT-induced ATM kinase activation is mediated by protein phosphatase 5 (PP5). Both in vitro and in vivo investigations revealed that the inhibition of the PP5-ATM axis by palbociclib after DNA damage is responsible for the synergism between palbociclib and RT.

CONCLUSION

Our findings provide a novel combination strategy against liver cancer cells. Clinical trials using palbociclib as an adjuvant in RT are warranted.

Abstract 762: Disrupting the glucose-influx induced β-catenin activation for the treatment of hepatocellular carcinoma

Background: Reprogramming of glucose metabolism is a critical hallmark in hepatocellular carcinoma (HCC), and alteration of WNT/β-catenin signaling is one of the most common molecular alterations observed in patients with HCC. Interestingly, some studies reported that high glucose exposure leaded to activation of WNT/β-catenin signaling. But, for HCC, whether the accelerated glucose metabolism affects β-catenin, and whether this singling pathway reserves potential for the development of novel anti-cancer treatment have not yet been explored.

Method:

HCC cells were exposed to different glucose conditions and various glucose transporter inhibitors, including Phloretin, WZB117, Canagliflozin, Dapagliflozin and Empagliflozin. Cells were examined for cell viability and molecular signaling after treatments. Huh7 xenografted tumor model was used for in vivo testing. Clinical HCC tumor tissues were examined by immunohistochemical stain.

Result:

HCC cells exposed to high glucose environment showed higher proliferation rate and upregulated β-catenin as comparing to those cultured in lower glucose-median. Notably, a similar association was observed in the clinical samples; HCC patients with higher glycemic level had stronger expressions of β-catenin in their tumors (p=0.034). Above data suggested that high glucose condition induced activation of β-catenin. Next, we asked whether blocking glucose influx attenuates this glucose-influx-mediated β-catenin activation and inhibits HCC cell growth. By treating HCC cells with various glucose transporter inhibitors, we found that canagliflozin, Phloretin and WZB117 attenuated

glucose influx of HCC cells, but only canagliflozin showed potent growth inhibition against HCC. Furthermore, treatment of canagliflozin leaded to a dose-dependent downregulation of β-catenin in HCC cells. Using cycloheximide and MG-132, we proved that canagliflozin treatment promoted the proteasome-mediated degradation of β-catenin protein. Since the phosphorylation of β-catenin is the initial step for its degradation, we examined the expression of p-β-catenin and found that canagliflozin treatment increased the expressions of p-Ser33/Ser37/Thr41-β-catenin and p-Ser45-β-catenin. Furthermore, the activity of protein phosphatase 2A (PP2A) was decreased in canagliflozin-treated HCC cells. The roles of glucose-influx and PP2A/p-β-catenin mediating the anti-HCC effects of canagliflozin were validated. Moreover, in vivo tumor growth inhibition of canagliflozin treatment was shown.

Conclusion:

Our results showed that high glucose upregulated beta-catenin signaling in HCC. Canagliflozin, by direct promoting the degradation of β-catenin protein and attenuating glucose-influx, inhibits the glucose-influx-mediated β-catenin activation and produces anti-HCC effects in vitro and in vivo.

Citation Format: Man-Hsin Hung, Li-Ju Chen, Pei-Yi Chu, Yao-Li Chen, Ming-Hsien Tsai, Feng-Shu Hsieh, Kuen-Feng Chen. Disrupting the glucose-influx induced β-catenin activation for the treatment of hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 762.

Antagonizing SET Augments the Effects of Radiation Therapy in Hepatocellular Carcinoma through Reactivation of PP2A-Mediated Akt Downregulation

Increasing evidence suggests that SET functions as an oncoprotein and promotes cancer survival and therapeutic resistance. However, whether SET affects radiation therapy (RT)-mediated anticancer effects has not yet been explored. We investigated the impact of SET on RT sensitivity in hepatocellular carcinoma (HCC). Using colony and hepatosphere formation assays, we found that RT-induced proliferative inhibition was critically associated with SET expression. We next tested a novel SET antagonist, N⁴-(3-ethynylphenyl)-6,7-dimethoxy-N²-(4-phenoxyphenyl) quinazoline-2,4-diamine (EMQA), in combination with RT. We showed that additive use of EMQA significantly enhanced the effects of RT against HCC in vitro and in vivo. Notably, compared with mice receiving either RT or EMQA alone, the growth of PLC5 xenografted tumor in mice receiving RT plus EMQA was significantly reduced without compromising treatment tolerability. Furthermore, we proved that antagonizing SET to restore protein phosphatase 2A-mediated phospho-Akt (p-AKT) downregulation was responsible for the synergism between EMQA and RT. Our data demonstrate a new oncogenic property of SET and provide preclinical evidence that combining a SET antagonist and RT may be effective for treatment of HCC. Further investigation is warranted to validate the clinical relevance of this approach.

Effect of intraoperative hyperoxia on the incidence of surgical site infections: a meta-analysis

BACKGROUND

Whether supplemental intraoperative oxygen reduces surgical site infections remains unclear. Recent recommendations from the World Health Organization and Center for Disease Control to routinely use high inspired oxygen concentrations to reduce infection risk have been widely criticized. We therefore performed a meta-analysis to evaluate the influence of inspired oxygen on infection risk, including a recent large trial.

METHODS

A systematic literature search was performed. Primary analysis included all eligible trials. Sensitivity analyses distinguished studies of colorectal and non-colorectal surgeries, and excluded studies with high risk of bias. Another post-hoc sensitivity analysis excluded studies from one author that appear questionable.

RESULTS

The primary analysis included 26 trials (N=14,710). The RR [95%CI] for wound infection was 0.81 [0.70, 0.94] in the high vs. low inspired oxygen groups. The effect remained significant in colorectal patients (N=10,469), 0.79 [0.66, 0.96], but not in other patients (N=4,241), 0.86 [0.69, 1.09]. When restricting the analysis to studies with low risk of bias, either by strict inclusion criteria (N=5,047) or by researchers' judgment (N=12,547), no significant benefit remained: 0.84 [0.67, 1.06] and 0.89 [0.76, 1.05], respectively.

CONCLUSIONS

When considering all available data, intraoperative hyperoxia reduced wound infection incidence. However, no significant benefit remained when analysis was restricted to objective- or investigator-identified low-bias studies, although those analyses were not as well-powered. Meta-analysis of the most reliable studies does not suggest that supplemental oxygen substantively reduces wound infection risk, but more research is needed to fully answer this question.

Regorafenib (Stivarga) pharmacologically targets epithelial-mesenchymal transition in colorectal cancer

Epithelial-to-mesenchymal transition (EMT) is well-known to evoke cancer invasion/metastasis, leading to a high frequency of mortality in patients with metastatic colorectal cancer (mCRC). Protein tyrosine phosphatase (PTPase)-targeted therapy has been identified as a novel cancer therapeutic. Previously, we proved that sorafenib with anti-EMT potency prevents TGF-β1-induced EMT/invasion by directly activating SH2-domain-containing phosphatase 1 (SHP-1)-dependent p-STAT3Tyr705 suppression in hepatocellular carcinoma. Regorafenib has a closely related chemical structure as sorafenib and is approved for the pharmacotherapy of mCRC. Herein, we evaluate whether regorafenib activates PTPase SHP-1 in the same way as sorafenib to abolish EMT-related invasion/metastasis in CRC. Notably, regorafenib exerted potent anti-EMT activity to curb TGF-β1-induced EMT/invasion in vitro as well inhibited lung metastatic outgrowth of SW480 mesenchymal cells in vivo. Mechanistically, regorafenib-enhanced SHP-1 activity significantly impeded TGF-β1-induced EMT/invasion via low p-STAT3Tyr705 level as proved by a SHP-1 inhibitor or siRNA-mediated SHP-1 depletion. Conversely, overexpression of SHP-1 further enhanced the inhibitory effects of regorafenib on TGF-β1-induced p-STAT3Tyr705 and EMT/invasion. Regorafenib directly activates SHP-1 by potently relieving the autoinhibited N-SH2 domain of SHP-1 to inhibit TGF-β1-induced p-STAT3Tyr705 and EMT/invasion. Importantly, the clinical evidence indicated that SHP-1 was positively correlated with E-cadherin and that significantly determined the overall survival of CRC patients. This result further confirms our in vitro data that SHP-1 is a negative regulatory PTPase in EMT regulation and serves as a pharmacological target for mCRC therapy. Collectively, activating PTPase SHP-1 by regorafenib focusing on its anti-EMT activity might be a useful pharmacotherapy for mCRC.

Moderate anemia at diagnosis is an independent prognostic marker of the EUTOS, Sokal, and Hasford scores for survival and treatment response in chronic-phase, chronic myeloid leukemia patients with frontline imatinib

OBJECTIVES

This study aimed to examine the prognostic value of anemia for the diagnosis of chronic myeloid leukemia in the chronic phase (CML-CP) receiving imatinib.

METHODS

One hundred and fifty-four CML-CP patients were enrolled. The influences of moderate anemia with hemoglobin (Hb) < 10 g/dl, four scoring systems, and the early molecular response at 3 months (BCR-ABL ≤10%; 3M-EMR) on the achievement of a deep molecular response (DMR, MR4.5), progression-free survival (PFS), event-free survival (EFS), and overall survival (OS) were compared.

RESULTS

Moderate anemia was identified in 44 (28.6%) patients. These patients had more aggressive baseline features and higher risks, as assessed by scoring systems, and less favorable treatment responses vs those without anemia, including 3M-EMR (50.0% vs 69.1%), a complete cytogenetic response at 6 months (20.5% vs 50.9%), and a major molecular response at 12 months (22.5% vs 45.2%), with a median follow-up of 54.0 months. Furthermore, an Hb of 10 g/dl better distinguished DMR, EFS, PFS, and OS than the EUTOS, Sokal, and Hasford scores, and better predicted the responses and survivals in combination with 3M-EMR than 3M-EMR alone.

CONCLUSIONS

This finding highlights the significance of anemia in CML-CP, and suggests that patients with anemia at diagnosis should be carefully monitored and might benefit from more potent TKIs if not achieving 3M-EMR.

Abstract 4192: Targeting SHP-1/p-Lyn signaling shows therapeutic potential in diffuse large B-cell lymphoma

Background:

Diffuse large B cell lymphoma (DLBCL) is one aggressive form of non-Hodgkin’s lymphoma. Genetic analyses revealed molecular heterogeneity of DLBCL tumors, classifying the cell-of-origin into two distinct molecular subtypes: germinal center B-cell (GCB) and activated B-cell (ABC). ABC-type DLBCL has a worse survival after upfront chemotherapy compared to GCB-type DLBCL, thus ABC-type DLBCL patients have an unmet medical need that warrants additional research efforts and new therapeutic options. In current study we explored the biological role and potential therapeutic implication of a protein phosphatase SHP-1 in DLBCL.

Methods:

DLBCL cell lines including ABC-like cell lines U2932, Ly-3 and GC-like cell lines DHL-6, Ly-7 and DB were used for in vitro studies. Cell viability was examined by MTT assay. Apoptotic effects were examined by flow cytometry and Western blot. Signal transduction pathways in cells were assessed by Western blot. In vivo therapeutic testing of SHP-1 agonists were performed in nude mice with DLBCL xenografts.

Results:

We first examined the protein expression of SHP-1 and its downstream p-STAT3 in a panel of DLBCL cell lines, and identified in general SHP-1/p-STAT3 expression was higher in ABC-like cells. Interestingly, the expressions of p-Lyn (Tyr396), p-BTK (Tyr223), key members of B-cell receptor (BCR) signaling pathway, were also higher in ABC-like cells. Knockdown or overexpression of SHP-1 protein expression revealed a reciprocal change of p-Lyn, suggesting SHP-1 negatively regulates phosphorylation of Lyn kinase. Immunoprecipitation experiments confirmed SHP-1 interact with Lyn in DLBCL cells. We previously developed direct SHP-1 agonists, namely SC-43 and SC-60, which could increase SHP-1 activities and induce apoptosis. Here we tested SC-43 and SC-60 in comparison to ibrutinib, a selective Bruton's tyrosine kinase (BTK) inhibitor. The SHP-1 agonists showed in general superior anti-proliferative and apoptotic effects, comparing to ibrutinib. Mechanistically, SHP-1 agonists enhanced SHP-1 activity, decreased BCR signaling p-Lyn and p-BTK, which led to apoptosis. In addition, SHP-1 agonists also down-regulated p-STAT3 as previously reported, which also contributes to anti-cancer effects. In vivo, SC-43 at doses of 10mg/kg/day and 30mg/kg/day orally showed comparable anti-tumor effects with ibrutinib at doses of 12.5 mg/kg/day and 25 mg/kg/day in mice bearing U2932 xenografts, respectively. Western blot confirmed SC-43 downregulation on p-Lyn and p-BTK in vivo.

Conclusions:

SHP-1 negatively regulates phosphorylation of Lyn, and targeting SHP-1/p-Lyn with direct SHP-1 agonists shows therapeutic potential in DLBCL.

Citation Format: Chun-Yu Liu, Man-Hsin Hung, Ming-Hsien Tsai, Pei-Yi Chu, Tzu-Ting Huang, Chun-Teng Huang, Chung-Wai Shiau, Kuen-Feng Chen. Targeting SHP-1/p-Lyn signaling shows therapeutic potential in diffuse large B-cell lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4192. doi:10.1158/1538-7445.AM2017-4192

Abstract 5190: Oncoprotein SET determines the radiosensitivity of hepatocellular carcinoma cell and antagonizing SET augments the effects of radiotherapy via reactivating PP2A-mediated Akt downregulation

Background:

SET is a novel oncoprotein with growing evidence suggesting its roles in promoting the survival of hepatocellular carcinoma (HCC) and other types of malignant disease. Notably, pre-clinical data suggesting SET overexpression in cancer cell leaded to the development of resistance to various anti-cancer medications, and antagonizing SET reversely enhanced therapeutic efficacy. Radiotherapy (RT) is a commonly used anti-cancer modality, but its role for the treatment of HCC is largely limited for the concern of endogenous radioresistance. In this report, we explored the role of SET regarding the radiosensitivity of HCC cells. Furthermore, we explored whether SET serve as a valid target to enhance RT against HCC.

Method:

A panel of HCC cell lines, including Hep3B, PLC5, HA22T and HA59T, were used for in vitro experiments, and the PLC5 subcutaneous xenograft mice model was used for in vivo testing. HCC cells and tumors were treated with RT and/or SET antagonist and harvested for subsequent experiments. The viability of cancer cells were assessed by sub-G1, colony and sphere formation assay. Molecular events were determined by western blot and PP2A activity.

Result:

Through manipulating the expression of SET in cancer cells, we showed the crucial role of SET in mediating the effects of RT in HCC cells. Using colony formation and hepatosphere formation assay, we showed that RT significantly reduced the number and size of both tumor colony and sphere formed by Hep3B and PLC5 cells. In contrast, ectopic expression of SET in Hep3B and PLC5 cells abolished the effects of RT. More importantly, SET-knockdown oppositely potentiated the RT-induced growth inhibition in HCC cells. Based on our findings, we hypothesized that targeting SET may exert potential to enhance RT for the treatment of HCC. In order to validate our hypothesis, we tested the effects of RT in combine with a novel SET antagonist, EMQA, developed and characterized in our previous works. As expected, we found that EMQA significantly potentiated the anti-HCC effects of RT in vitro and in vivo. Moreover, we found that antagonizing SET to restore PP2A-mediated p-Akt downregulation was responsible for the synergism between EMQA and RT.

Conclusion

Oncoprotein SET plays a critical role in affecting the radiosensitivity of HCC cells. Using SET antagonist plus RT showed promising results in pre-clinical HCC models, and yields further investigation.

Citation Format: Man-Hsin Hung, Chao-Yuan Huang, Chih-Ting Shih, Min-Hsien Tsai, Yung-Jen Hsiao, Tzu-I Chao, Feng-Shu Hsieh, Chung-Wai Shiau, Kuen-Feng Chen. Oncoprotein SET determines the radiosensitivity of hepatocellular carcinoma cell and antagonizing SET augments the effects of radiotherapy via reactivating PP2A-mediated Akt downregulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5190. doi:10.1158/1538-7445.AM2017-5190

Palbociclib induces activation of AMPK and inhibits hepatocellular carcinoma in a CDK4/6-independent manner

Palbociclib, a CDK4/6 inhibitor, has recently been approved for hormone receptor‐positive breast cancer patients. The effects of palbociclib as a treatment for other malignancies, including hepatocellular carcinoma (HCC), are of great clinical interest and are under active investigation. Here, we report the effects and a novel mechanism of action of palbociclib in HCC. We found that palbociclib induced both autophagy and apoptosis in HCC cells through a mechanism involving 5′ AMP‐activated protein kinase (AMPK) activation and protein phosphatase 5 (PP5) inhibition. Blockade of AMPK signals or ectopic expression of PP5 counteracted the effect of palbociclib, confirming the involvement of the PP5/AMPK axis in palbociclib‐mediated HCC cell death. However, CDK4/6 inhibition by lentivirus‐mediated shRNA expression did not reproduce the effect of palbociclib‐treated cells, suggesting that the anti‐HCC effect of palbociclib is independent of CDK4/6. Moreover, two other CDK4/6 inhibitors (ribociclib and abemaciclib) had minimal effects on HCC cell viability and the PP5/AMPK axis. Palbociclib also demonstrated significant tumor‐suppressive activity in a HCC xenograft model, which was associated with upregulation of pAMPK and PP5 inhibition. Finally, we analyzed 153 HCC clinical samples and found that PP5 expression was highly tumor specific and was associated with poor clinical features. Taken together, we conclude that palbociclib exerted antitumor activity against HCC through the PP5/AMPK axis independent of CDK4/6. Our findings provide a novel mechanistic basis for palbociclib and reveal the therapeutic potential of targeting PP5/AMPK signaling with a PP5 inhibitor for the treatment of hepatocellular carcinoma.

Carfilzomib induces leukaemia cell apoptosis via inhibiting ELK1/KIAA1524 (Elk-1/CIP2A) and activating PP2A not related to proteasome inhibition

Enhancing the tumour suppressive activity of protein phosphatase 2A (PP2A) has been suggested to be an anti-leukaemic strategy. KIAA1524 (also termed CIP2A), an oncoprotein inhibiting PP2A, is associated with disease progression in chronic myeloid leukaemia and may be prognostic in cytogenetically normal acute myeloid leukaemia. Here we demonstrated that the selective proteasome inhibitor, carfilzomib, induced apoptosis in sensitive primary leukaemia cells and in sensitive leukaemia cell lines, associated with KIAA1524 protein downregulation, increased PP2A activity and decreased p-Akt, but not with the proteasome inhibition effect of carfilzomib. Ectopic expression of KIAA1524, or pretreatment with the PP2A inhibitor, okadaic acid, suppressed carfilzomib-induced apoptosis and KIAA1524 downregulation in sensitive cells, whereas co-treatment with the PP2A agonist, forskolin, enhanced carfilzomib-induced apoptosis in resistant cells. Mechanistically, carfilzomib affected KIAA1524 transcription through disturbing ELK1 (Elk-1) binding to the KIAA1524 promoter. Moreover, the drug sensitivity and mechanism of carfilzomib in xenograft mouse models correlated well with the effects of carfilzomib on KIAA1524 and p-Akt expression, as well as PP2A activity. Our data disclosed a novel drug mechanism of carfilzomib in leukaemia cells and suggests the potential therapeutic implication of KIAA1524 in leukaemia treatment.

Protein tyrosine phosphatase 1B targets PITX1/p120RasGAP thus showing therapeutic potential in colorectal carcinoma

Protein tyrosine phosphatase 1B (PTP1B) is known to promote the pathogenesis of diabetes and obesity by negatively regulating insulin and leptin pathways, but its role associated with colon carcinogenesis is still under debate. In this study, we demonstrated the oncogenic role of PTP1B in promoting colon carcinogenesis and predicting worse clinical outcomes in CRC patients. By co-immunoprecipitation, we showed that PITX1 was a novel substrate of PTP1B. Through direct dephosphorylation at Y160, Y175 and Y179, PTP1B destabilized PITX1, which resulted in downregulation of the PITX1/p120RasGAP axis. Interestingly, we found that regorafenib, the approved target agent for advanced CRC patients, exerted a novel property against PTP1B. By inhibiting PTP1B activity, regorafenib treatment augmented the stability of PITX1 protein and upregulated the expression of p120RasGAP in CRC. Importantly, we found that this PTP1B-dependant PITX1/p120RasGAP axis determines the in vitro anti-CRC effects of regorafenib. The above-mentioned effects of regorafenib were confirmed by the HT-29 xenograft tumor model. In conclusion, we demonstrated a novel oncogenic mechanism of PTP1B on affecting PITX1/p120RasGAP in CRC. Regorafenib inhibited CRC survival through reserving PTP1B-dependant PITX1/p120RasGAP downregulation. PTP1B may be a potential biomarker predicting regorafenib effectiveness, and a potential solution for CRC.

Pharmacological Targeting SHP-1-STAT3 Signaling Is a Promising Therapeutic Approach for the Treatment of Colorectal Cancer

STAT3 activation is associated with poor prognosis in human colorectal cancer (CRC). Our previous data demonstrated that regorafenib (Stivarga) is a pharmacological agonist of SH2 domain-containing phosphatase 1 (SHP-1) that enhances SHP-1 activity and induces apoptosis by targeting STAT3 signals in CRC. This study aimed to find a therapeutic drug that is more effective than regorafenib for CRC treatment. Here, we showed that SC-43 was more effective than regorafenib at inducing apoptosis in vitro and suppressing tumorigenesis in vivo. SC-43 significantly increased SHP-1 activity, downregulated p-STAT3^Tyr705 level, and induced apoptosis in CRC cells. An SHP-1 inhibitor or knockdown of SHP-1 by siRNA both significantly rescued the SC-43–induced apoptosis and decreased p-STAT3^Tyr705 level. Conversely, SHP-1 overexpression increased the effects of SC-43 on apoptosis and p-STAT3^Tyr705 level. These data suggest that SC-43–induced apoptosis mediated through the loss of p-STAT3^Tyr705 was dependent on SHP-1 function. Importantly, SC-43–enhanced SHP-1 activity was because of the docking potential of SC-43, which relieved the autoinhibited N-SH2 domain of SHP-1 and inhibited p-STAT3^Tyr705 signals. Importantly, we observed that a significant negative correlation existed between SHP-1 and p-STAT3^Tyr705expression in CRC patients (P = .038). Patients with strong SHP-1 and weak p-STAT3^Tyr705 expression had significantly higher overall survival compared with patients with weak SHP-1 and strong p-STAT3^Tyr705 expression (P = .029). In conclusion, SHP-1 is suitable to be a useful prognostic marker and a pharmacological target for CRC treatment. Targeting SHP-1-STAT3 signaling by SC-43 may serve as a promising pharmacotherapy for CRC.

Abstract 3772: SHP-1 determines the radiosensitivity of liver cancer cell and dovitinib acts as a novel radiosensitizer in hepatocellular carcinoma via targeting SHP-1/STAT3 signaling

Background

Hepatocellular carcinoma (HCC) is one of the most lethal human malignancies and curative therapy is not an option for most patients. There is growing interest in the potential benefit of radiotherapy (RT)-integrated therapy. This study aimed to investigate the biological impacts of a novel tumor suppressor Src homology 2 (SH2) domain-containing phosphatase 1 (SHP-1) and its downstream effecter, STAT3, in regulating the radiosensitivity of HCC cells. Furthermore, we explored the efficacy and mechanism of an investigational drug, dovitinib, used in combination with RT.

Material and methods

To understand the impacts of SHP-1/STAT3 signaling affects radiosensitivity, HCC cells with ectopic expression of STAT3, SHP-1 and a catalytic mutant SHP-1 were treated with or without radiotherapy and analyzed by flow cytometry and colony formation assay. Furthermore, five HCC cell lines (PLC5, Hep3B, SK-Hep1, HA59T and Huh-7) were treated with dovitnib, RT or both. The in vitro and in vivo effects of above-mentioned treatments were analyzed.

Results

By sub-G1 analysis and colony formation, we found that HCC cell with ectopic expression of SHP-1 was much more sensitive to RT-induced apoptotic effects, while overexpression of STAT3 or catalytic-dead mutant SHP-1 restored RT-induced reduction of HCC cell survival. Next, we investigated the effects of dovitinib, which showed that dovitinib treatment resulted in SHP-1-mediated downregulation of p-STAT3 and promoted potent apoptosis of HCC cells. Ectopic expression of STAT3, or inhibition of SHP-1 diminished the effects of dovitinib on HCC cells. Furthermore, by ectopic expression and purified recombinant proteins of various mutant forms of SHP-1, the N-SH2 domain of SHP-1 was found to be required for dovitinib treatment.

Importantly, we found that dovitinib potentiated the in vitor and in vivo effects of RT in HCC cells through affecting the SHP-1/STAT3 signaling.

Conclusions

SHP-1/STAT3 signaling is critically associated with the radiosensitivity of HCC cells. A combination therapy with RT and the SHP-1 agonist, such as dovitinib, resulted in enhanced in vitro and in vivo anti-HCC effects.

Citation Format: Man-Hsin Hung, Chao-Yuan Huang, Wei-Tien Tai, Ming-Hsien Tsai, Chih-Ting Shin, Szu-Yuan Wu, Chung-Wai Shiau, Kuen-Feng Chen. SHP-1 determines the radiosensitivity of liver cancer cell and dovitinib acts as a novel radiosensitizer in hepatocellular carcinoma via targeting SHP-1/STAT3 signaling. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3772.

Decision-tree algorithm for optimized hematopoietic progenitor cell-based predictions in peripheral blood stem cell mobilization

BACKGROUND

Enumerating hematopoietic progenitor cells (HPCs) by using an automated hematology analyzer is a rapid, inexpensive, and simple method for predicting a successful harvest compared with enumerating circulating CD34+ cells. However, the optimal HPC cutoff count and the indicating factors to be considered for improved predicting have not yet been determined.

STUDY DESIGN AND METHODS

Between 2007 and 2012, a total of 189 consecutive patients who proceeded to peripheral blood stem cell (PBSC) harvesting were retrospectively recruited. Baseline characteristics were analyzed to identify the risk factors for a failed harvest, which were defined as less than 2 × 10(6) CD34+ cells/kg. Variables identified by multivariate logistic regression and correlation analysis for predicting a successful harvest were subjected to classification and regression tree (CART) analysis.

RESULTS

PBSCs were successfully harvested in 154 (81.5%) patients. An age of at least 60 years, a diagnosis of a solid tumor, at least five prior chemotherapy cycles, prior radiotherapy, and mobilization with granulocyte-colony-stimulating factor alone or high-dose cyclophosphamide were independent baseline predictors of poor mobilization. In CART analysis, patients with zero to two host risk factors and either higher HPC (≥28 × 10(6) /L) or mononuclear cell (MNC; ≥3.5 × 10(9) /L) counts were categorized as good mobilizers and their harvest success rate was 92.3%. By contrast, 30.3% of harvests were adequate in the patients with three to five host risk factors and lower HPC and MNC counts.

CONCLUSION

A CART algorithm incorporating host predictors and HPC and MNC counts improves predictions in a successful harvest and might reduce the necessity of monitoring peripheral CD34+ cells.

Protein tyrosine phosphatase 1B dephosphorylates PITX1 and regulates p120RasGAP in hepatocellular carcinoma

The effective therapeutic targets for hepatocellular carcinoma remain limited. Pituitary homeobox 1 (PITX1) functions as a tumor suppressor in hepatocarcinogenesis by regulating the expression level of Ras guanosine triphosphatase-activating protein. Here, we report that protein tyrosine phosphatases 1B (PTP1B) directly dephosphorylated PITX1 at Y160, Y175, and Y179 to further weaken the protein stability of PITX. The PTP1B-dependent decline of PITX1 reduced its transcriptional activity for p120RasGAP (RASA1), a Ras guanosine triphosphatase-activating protein. Both silencing of PTP1B and PTP1B inhibitor up-regulated the PITX1-p120RasGAP axis through hyperphosphorylation of PITX1. Sorafenib, the first and only targeted drug approved for hepatocellular carcinoma, directly decreased PTP1B activity and promoted the expression of PITX1 and p120RasGAP by PITX1 hyperphosphorylation. Molecular docking also supported the potential interaction between PTP1B and sorafenib. PTP1B overexpression impaired the sensitivity of sorafenib in vitro and in vivo, implying that PTP1B has a significant effect on sorafenib-induced apoptosis. In sorafenib-treated tumor samples, we further found inhibition of PTP1B activity and up-regulation of the PITX1-p120RasGAP axis, suggesting that PTP1B inhibitor may be effective for the treatment of hepatocellular carcinoma. By immunohistochemical staining of hepatic tumor tissue from 155 patients, the expression of PTP1B was significantly in tumor parts higher than nontumor parts (P = 0.02). Furthermore, high expression of PTP1B was significantly associated with poor tumor differentiation (P = 0.031).

CONCLUSION

PTP1B dephosphorylates PITX1 to weaken its protein stability and the transcriptional activity for p120RasGAP gene expression and acts as a determinant of the sorafenib-mediated drug effect; targeting the PITX1-p120RasGAP axis with a PTP1B inhibitor may provide a new therapy for patients with hepatocellular carcinoma.

SH2 domain-containing phosphatase 1 regulates pyruvate kinase M2 in hepatocellular carcinoma

Pyruvate kinase M2 (PKM2) is known to promote tumourigenesis through dimer formation of p-PKM2Y105. Here, we investigated whether SH2-containing protein tyrosine phosphatase 1 (SHP-1) decreases p-PKM2Y105 expression and, thus, determines the sensitivity of sorafenib through inhibiting the nuclear-related function of PKM2. Immunoprecipitation and immunoblot confirmed the effect of SHP-1 on PKM2Y105 dephosphorylation. Lactate production was assayed in cells and tumor samples to determine whether sorafenib reversed the Warburg effect. Clinical hepatocellular carcinoma (HCC) tumor samples were assessed for PKM2 expression. SHP-1 directly dephosphorylated PKM2 at Y105 and further decreased the proliferative activity of PKM2; similar effects were found in sorafenib-treated HCC cells. PKM2 was also found to determine the sensitivity of targeted drugs, such as sorafenib, brivanib, and sunitinib, by SHP-1 activation. Significant sphere-forming activity was found in HCC cells stably expressing PKM2. Clinical findings suggest that PKM2 acts as a predicting factor of early recurrence in patients with HCC, particularly those without known risk factors (63.6%). SHP-1 dephosphorylates PKM2 at Y105 to inhibit nuclear function of PKM2 and determines the efficacy of targeted drugs. Targeting PKM2 by SHP-1 might provide new therapeutic insights for patients with HCC.

Carvedilol, Bisoprolol, and Metoprolol Use in Patients With Coexistent Heart Failure and Chronic Obstructive Pulmonary Disease

Beta (β)-blockers are under-prescribed in patients with heart failure (HF) and concurrent chronic obstructive pulmonary disease (COPD) due to concerns about adverse pulmonary effects and a poor understanding of the effects of these drugs. We aimed to evaluate the survival effects of β-blockers in patients with coexistent HF and COPD. Using the Taiwan National Health Insurance Research Database, we conducted a nationwide population-based study. Patients with coexistent HF and COPD diagnosed between 2000 and 2009 were enrolled. Doses of the 3 β-blockers proven to be beneficial to HF (carvedilol, bisoprolol, and metoprolol) during the study period were extracted. The primary endpoint was cumulative survival. Patients were followed until December 31, 2009. The study included 11,558 subjects, with a mean follow-up period of 4.07 years. After adjustment for age, sex, comorbidities, and severity of HF and COPD, bisoprolol use showed a dose-response survival benefit [low dose: adjusted hazard ratio (HR) = 0.76, 95% confidence interval (CI) = 0.59-0.97, P = 0.030; high dose: adjusted HR = 0.40, 95% CI = 0.26-0.63, P < 0.001] compared with nonusers, whereas no survival difference was observed for carvedilol or metoprolol. Compared with patients with HF alone, this special HF + COPD cohort received significantly fewer targeted β-blockers (108.8 vs 137.3 defined daily doses (DDDs)/person-year, P < 0.001) and bisoprolol (57.9 vs 70.8 DDDs/person-year, P < 0.001). In patients with coexisting HF and COPD, this study demonstrated a dose-response survival benefit of bisoprolol use, but not of carvedilol or metoprolol use.

Dovitinib Acts As a Novel Radiosensitizer in Hepatocellular Carcinoma by Targeting SHP-1/STAT3 Signaling

PURPOSE

Hepatocellular carcinoma (HCC) is among the most lethal human malignancies, and curative therapy is not an option for most patients. There is growing interest in the potential benefit of combining targeted therapies with radiation therapy (RT). This study aimed to characterize the efficacy and mechanism of an investigational drug, dovitinib, used in combination with RT.

METHODS AND MATERIALS

HCC cell lines (PLC5, Hep3B, SK-Hep1, HA59T, and Huh-7) were treated with dovitinib, RT, or both, and apoptosis and signal transduction were analyzed.

RESULTS

Dovitinib treatment resulted in Src homology region 2 (SH2) domain-containing phosphatase 1 (SHP-1)-mediated downregulation of p-STAT3 and promoted potent apoptosis of HCC cells. Ectopic expression of STAT3, or inhibition of SHP-1, diminished the effects of dovitinib on HCC cells. By ectopic expression and purified recombinant proteins of various mutant forms of SHP-1, the N-SH2 domain of SHP-1 was found to be required for dovitinib treatment. Overexpression of STAT3 or catalytic-dead mutant SHP-1 restored RT-induced reduction of HCC cell survival. Conversely, ectopic expression of SHP-1 or activation of SHP-1 by dovitinib enhanced the effects of RT against HCC in vitro and in vivo.

CONCLUSIONS

SHP-1/STAT3 signaling is critically associated with the radiosensitivity of HCC cells. Combination therapy with RT and the SHP-1 agonist, such as dovitinib, resulted in enhanced in vitro and in vivo anti-HCC effects.

SET antagonist enhances the chemosensitivity of non-small cell lung cancer cells by reactivating protein phosphatase 2A

SET is known as a potent PP2A inhibitor, however, its oncogenic role including its tumorigenic potential and involvement in the development of chemoresistance in non-small cell lung cancer (NSCLC) has not yet been fully discussed. In present study, we investigated the oncogenic role of SET by SET-knockdown and showed that SET silencing impaired cell growth rate, colony formation and tumor sphere formation in A549 cells. Notably, silencing SET enhanced the pro-apoptotic effects of paclitaxel, while ectopic expression of SET diminished the sensitivity of NSCLC cells to paclitaxel. Since the SET protein was shown to affect chemosensitivity, we next examined whether combining a novel SET antagonist, EMQA, sensitized NSCLC cells to paclitaxel. Both the in vitro and in vivo experiments suggested that EMQA and paclitaxel combination treatment was synergistic. Importantly, we found that downregulating p-Akt by inhibiting SET-mediated protein phosphatase 2A (PP2A) inactivation determined the pro-apoptotic effects of EMQA and paclitaxel combination treatment. To dissect the critical site for EMQA functioning, we generated several truncated SET proteins. By analysis of the effects of EMQA on the binding affinities of different truncated SET proteins to PP2A-catalytic subunits, we revealed that the 227-277 amino-acid sequence is critical for EMQA-induced SET inhibition. Our findings demonstrate the critical role of SET in NSCLC, particularly in the development of chemoresistance. The synergistic effects of paclitaxel and the SET antagonist shown in current study encourage further validation of the clinical potential of this combination.

SHP-1 is a target of regorafenib in colorectal cancer

Regorafenib is an inhibitor of multiple protein kinases which exerts antitumor and antimetastatic activities in metastatic colorectal cancer (CRC). SH2 domain-containing phosphatase 1 (SHP-1) is reported to have tumor suppressive potential because it acts as a negative regulator of p-STAT3^Tyr705 signaling. However, little is known about the mechanism regarding regorafenib affects SHP-1 tyrosine phosphatase activity and leads to apoptosis and tumor suppression in CRC. Here, we found that regorafenib triggered apoptotic cell death and significantly enhanced SHP-1 activity, which dramatically decreased the phosphorylated form of STAT3 at Tyr705 (p-STAT3^Tyr705). Importantly, regorafenib augmented SHP-1 activity by direct disruption of the association between N-SH2 and catalytic PTP domain of SHP-1. Deletion of the N-SH2 domain (dN1) or point mutation (D61A) of SHP-1 blocked the effect of regorafenib-induced SHP-1 activity, growth inhibition and a decrease of p-STAT3^Tyr705 expression, suggesting that regorafenib triggers a conformational change in SHP-1 by relieving its autoinhibition. In vivo assay showed that regorafenib significantly inhibited xenograft growth and decreased p-STAT3^Tyr705 expression but induced higher SHP-1 activity. Collectively, regorafenib is a novel SHP-1 agonist exerts superior anti-tumor effects by enhancing SHP-1 activity that directly targets p-STAT3^Tyr705. Small molecule-enhancement of SHP-1 activity may be a promising therapeutic approach for CRC treatment.

A combination of sorafenib and SC-43 is a synergistic SHP-1 agonist duo to advance hepatocellular carcinoma therapy

Sorafenib is the first and currently the only standard treatment for advanced hepatocellular carcinoma (HCC). We previously developed a sorafenib derivative SC-43, which exhibits much more enhanced anti-HCC activity than sorafenib and also promotes apoptosis in sorafenib-resistant HCC cells. Herein, a novel "sorafenib plus" combination therapy was developed by coupling sorafenib treatment with SC-43. Both sorafenib and SC-43 are proven Src homology region 2 domain containing phosphatase 1 (SHP-1) agonists. The combined actions of sorafenib and SC-43 enhanced SHP-1 activity, which was associated with diminished STAT3-related signals and stronger expression of apoptotic genes above that of either drug alone, culminating in increased cell death. Decreased p-STAT3 signaling and tumor size, as well as increased SHP-1 activity were observed in mice receiving the combination therapy in a subcutaneous HCC model. More reduced orthotopic HCC tumor size and prolonged survival were also observed in mice in the combination treatment arm compared to mice in either of the monotherapy arms. These results in the preclinical setting pave the way for further clinical studies to treat unresectable HCC.

Risk of Ischemic Stroke in Patients With Gastric Cancer: A Nationwide Population-Based Cohort Study

Improvements in therapeutic modalities have prolonged the survival of gastric cancer patients. Comorbidities such as thromboembolic events that emerge as a result of disease complexities and/or treatments received have not been considered. The objectives of this study are to examine the relationship between gastric cancer and ischemic stroke, and to determine predictive risk factors. A nationwide population-based cohort study was conducted using data from the Taiwan National Health Insurance database. A total of 45,060 gastric cancer patients and non-cancer counterparts without antecedent stroke were recruited. Hazard ratios (HRs) and the cumulative incidence of ischemic stroke were calculated, and risk factors for ischemic stroke were assessed. Gastric cancer patients were associated with higher risk of ischemic stroke (HR 1.11, 95% confidence interval [CI] 1.03-1.19, P = 0.007), especially in participants younger than 65 years (HR 1.61, 95% CI 1.39-1.86, P < 0.001) and in female participants (HR 1.30, 95% CI 1.14-1.49; P < 0.001) when compared with the matched cohort. Independent risk factors of ischemic stroke in gastric cancer patients included age, hypertension, atrial fibrillation, dyslipidemia, and having received major surgery for gastric cancer. Our findings suggest the importance of stroke surveillance and prevention strategies in high-risk patients. Having received major surgery for gastric cancer is a significant risk factor in these patients.

Abstract 2924: Suppressing SET reactivates PP2A function in EGFR wide-type NSCLC and synergizes with taxol to exert anti-cancer effects

Background:

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-associated death in the world. Conventional chemotherapy is the standard-of-care for majority of patients with advance NSCLC and tyrosine kinase inhibitors of epithelial growth factor receptor (EGFR) only benefit patients with tumor containing specific mutation forms of EGFR. However, high disease recurrence rate after currently available therapeutics limited patient's survival. Therefore, there is a timely need to improve current treatment for patients with NSCLC, especially those with EGFR wide type tumors.

Protein phosphatase 2A (PP2A) is an important tumor suppression whose function is inhibited in tumor tissue by the appearance of SET. In current study, we showed that inhibiting SET binding to PP2A by a novel small molecular compound significantly improved the chemosensitivity of EGFR wide-type NSCLC cells.

Method:

EGFR wide-type NSCLC cell lines, including A549, H358 and H460, were treated with taxol and a novel quinzoline derivative, PA, which was designed and developed to interrupt the binding of SET to PP2A. Apoptosis of cancer cell, signal transduction and phosphatase activity were analyzed after treatments. Combination index (CI) was applied to determine the synergistic effects of PA and taxol. Co-immunoprecipitation (co-IP) and proximity ligation assay (PLA) were used to identify in vivo binding between SET and PP2A. In vivo anti-tumor effects of treatment containing PA and taxol were also determined in A549 xenografted mice.

Results:

After treating the cancer cells with PA and taxol, apoptosis of cancer cells, in concordance with enhancing PP2A-dependent p-Akt downregulation, were observed in a dose-dependent manner in all EGFR wide-type NSCLC cell lines. CI determined by the results of sub-G1 analysis confirmed the synergy between PA and taxol. Overexpression of Akt and inhibition of PP2A diminished the therapeutic effects of this combination. By two different strategies, co-IP and PLA, we found that this combination treatment inhibited the association of SET and PP2A within lung cancer cells. When overexpression SET in treated cancer cells, the therapeutic effects of this combination were abolished. The anti-tumor effects of treatment combining PA and taxol were also validated in A549 xenografted mice. Our data suggested that PP2A inactivation determines the drug sensitivity of taxol in lung cancer cells, and by interfering the binding of SET and PP2A, PA significantly promote PP2A activity and increase the cytotoxic effects of taxol in EGFR wide-type NSCLC.

Conclusion:

By interfering the binding of SET to PP2A, the novel PP2A enhancer, PA, is shown to reactivate PP2A and work synergistically with taxol for the treatment of EGFR wide-type NSCLC.

Citation Format: Man-Hsin Hung, Chung-Wai Shiau, Yung-Jen Hsiao, Hui-Chuan Yu, Wei-Tien Tai, Chun-Yu Liu, Cheng-Yi Wang, Kuen-Feng Chen. Suppressing SET reactivates PP2A function in EGFR wide-type NSCLC and synergizes with taxol to exert anti-cancer effects. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2924. doi:10.1158/1538-7445.AM2015-2924

Abstract 1737: Carfilzomib transcriptionally regulates CIP2A/PP2A/p-Akt signaling and induces apoptosis in leukemia cells

Background: Protein phosphatase 2A (PP2A) has been shown to be an important tumor suppressor protein and loss of PP2A function has been identified in several solid cancers and in leukemias. Recent studies have suggested strategies for enhancing PP2A activity as an anti-leukemic approach. Among the potential key players regulating PP2A, a new oncoprotein, called cancerous inhibitor of protein phosphatase 2A (CIP2A), is recently identified as a key factor in the development of malignancies in various human cells. Previously we studied novel drug mechanisms of bortezomib, a proteasome inhibitor, on acute leukemia cells. We discovered that CIP2A plays an indispensable role in mediating bortezomib-induced apoptosis in acute leukemia cells (Hematologica 2013), hepatocellular carcinoma cells (Oncogene 2010) and in breast cancer cells (Breast Cancer Research 2012). Importantly, this mechanism by bortezomib is independent to its proteasome inhibition. Carfilzomib, a more selective proteasome inhibitor than bortezomib, has shown efficacy in multiple myeloma and is being investigated in phase III clinical trials. In this study, we examined the effect of carfilzomib on CIP2A in leukemia cells.

Methods: Leukemia cell lines (HL-60, KG-1, THP-1, and K562) were used for in vitro studies. Apoptosis was examined by both flow cytometry and Western blot. Signal transduction pathways in cells were assessed by Western Blot. Quantitative RT-PCR was used for assessing gene transcription. In vivo efficacy of carfilzomib was tested in nude mice with subcutaneous leukemia xenografts.

Results: We found carfilzomib induced differential antiproliferative effects and apoptosis. HL-60, KG-1 and THP-1, but not K562 cells, were sensitive to carfilzomib-induced apoptosis. Similarly, carfilzomib-induced apoptosis may be dissociated with its proteasome inhibition. We found CIP2A mediated this apoptotic effect of carfilzomib in leukemia cells. Carfilzomib down-regulated CIP2A in association with p-Akt downregulation. Furthermore, carfilzomib increased PP2A activity and over-expression of CIP2A up-regulated p-Akt and suppressed carfilzomib-induced apoptosis. In addition, carfilzomib downregulated CIP2A mRNA but did not affect the degradation of CIP2A protein. Further dissecting the regulatory mechanism showed that carfilzomib may affect CIP2A transcription though transcriptional factors. Importantly, carfilzomib demonstrated anti-tumor activity in xenografted mice models.

Conclusions: CIP2A is a major determinant mediating carfilzomib-induced apoptosis in leukemia cells and may be a therapeutic target in leukemia. This study disclosed a novel drug mechanism of carfilzomib in leukemia cells. (Supported by Taiwan Clinical Oncology Research Foundation, MOST 103-2325-B-075-002, V103C-141; and TVGH-NTUH Joint Research Program VN103-08)

Citation Format: Chun-Yu Liu, Wen-Chun Tsai, Man-Hsin Hung, Yuan-Bin Yu, Po-Shen Ko, Cheng-Hwai Tzeng, Chung-Wai Shiau, Kuen-Feng Chen. Carfilzomib transcriptionally regulates CIP2A/PP2A/p-Akt signaling and induces apoptosis in leukemia cells. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1737. doi:10.1158/1538-7445.AM2015-1737

Abstract 4447: Targeting SET oncoprotein reactivates the tumor-suppressor PP2A and shows synergy with sorafenib in hepatocellular carcinoma

Background:

Hepatocellular carcinoma (HCC) is the fifth major cancer in the world. Sorafenib is the first and only approved targeted therapy for patients with advanced HCC that brought only a 3-month additive survival benefit to patient. Thus, there is an unmet need for developing effective treatment against HCC. Protein phosphatase 2A (PP2A) is an important tumor suppressor whose functions are suppressed by the presence of its cancerous inhibitor, such as SET/I2PP2A and cancerous inhibitor of PP2A (CIP2A). Previously, we’ve shown that enhancing PP2A activity by inhibiting CIP2A promotes apoptosis of HCC (Oncogene 2010, MCT 2011). Here, we report the anti-HCC potential of a new approach to reactivate PP2A by interrupting the binding between SET and PP2A.

Method:

Using the quinzoline backbone, we designed and developed a novel PP2A activator, PA. HCC cell lines were treated with PA alone or in combination with sorafenib, and apoptosis, signal transduction and phosphatse activity were analyzed. Combination index (CI) was used to evaluate the synergy of combining PA and sorafenib. Small interference RNA was applied to silence gene; co-immunoprecipitation (co-IP) and proximity ligation assay (PLA) were used to determine the association of SET and PP2A within tumor cells. In vivo anti-HCC effects of PA and combination therapy of PA and sorafenib were tested in xenografted nude mice.

Results:

PA induced apoptosis, in association with reactivation of PP2A and downregulation of p-AKT, in a dose-dependent manner in HCC cell lines (PLC5, Hep3B, SK-Hep1, Huh7). Overexpression of Akt and knockdown of PP2A abolished the anti-HCC effects of PA. Using co-IP and PLA, we found that PA interrupts the binding of SET and PP2A within HCC cells in a dose-dependent and time-dependent manner. These data indicated that inhibition of SET-associated PP2A inactivation mediated the downregulation of p-Akt and the cytotoxic effects of PA against HCC. In addition, adding PA to sorafenib significantly induced more potent cell death than sorafenib alone in all HCC cell lines tested. CI suggested good synergy between PA and sorafenib under the combination ratio of 1:5. Importantly, the anti-tumor effects of PA and PA combining with sorafenib were validated in PLC5 xenografted tumors.

Conclusion:

In the current study, we showed that interfering the binding of SET to PP2A induce potent cellular death through PP2A-dependent p-Akt downregulation. This novel approach demonstrates great potency of PP2A enhancer and its synergy with sorafenib for the treatment of HCC.

Citation Format: Man-Hsin Hung, Chung-Wai Shiau, Chih-Ting Shin, Hui-Chuan Yu, Wei-Tien Tai, Chun-Yu Liu, Cheng-Yi Wang, Kuen-Feng Chen. Targeting SET oncoprotein reactivates the tumor-suppressor PP2A and shows synergy with sorafenib in hepatocellular carcinoma. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4447. doi:10.1158/1538-7445.AM2015-4447

Secondary primary malignancy risk among patients with esophageal cancer in Taiwan: a nationwide population-based study

Background

To evaluate the risk and sites of metachronous secondary primary malignancies (SPMs) among patients with esophageal cancer.

Methods

Newly diagnosed esophageal cancer patients between 1997 and 2011 were recruited. To avoid surveillance bias, SPMs that developed within one year were excluded. Standardized incidence ratios (SIRs) of metachronous SPMs in these patients were calculated by comparing to the cancer incidence in the general population. Risk factors for SPM development, included age, sex, comorbidities and cancer-related treatments, were estimated by Cox proportional hazards models.

Results

During the 15-year study period, 870 SPMs developed among 18,026 esophageal cancer patients, with a follow-up of 27,056 person-years. The SIR for all cancers was 3.53. The SIR of follow-up period ≥ 10 years was 3.56; 5–10 years, 3.14; and 1–5 years, 3.06. The cancer SIRs of head and neck (15.83), stomach (3.30), lung and mediastinum (2.10), kidney (2.24) and leukemia (2.72), were significantly increased. Multivariate analysis showed that age ≥ 60 years (hazard ratio [HR] 0.74), being male (HR 1.46) and liver cirrhosis (HR 1.46) were independent factors. According to the treatments, major surgery (HR 1.24) increased the risk, but chemotherapy was nearly significant.

Conclusions

Patients with esophageal cancer were at increased risk of developing metachronous SPMs. The SIR remained high in follow-up > 10 years, so that close monitoring may be needed for early detection of SPM among these esophageal cancer patients.

Lymphocyte/monocyte ratio and cycles of rituximab-containing therapy are risk factors for hepatitis B virus reactivation in patients with diffuse large B-cell lymphoma and resolved hepatitis B

Reactivation of hepatitis B virus (HBV) following rituximab (R)-containing chemotherapy for lymphoma is a major concern, and risk factors remain to be defined. We enrolled 190 patients diagnosed with diffuse large B-cell lymphoma (DLBCL) and resolved hepatitis B, receiving first-line R-CHOP (cyclophosphamide, doxorubicin, vincristine and prednisolone)-based regimens. Twenty-seven patients (14.2%) developed HBV reactivation during a median follow-up of 23.6 months. Two independent risk factors were identified: cycles of rituximab>8 (hazard ratio [HR], 2.797; 95% confidence interval [CI], 1.184-6.612) and lymphocyte/monocyte ratio (LMR)<2.50 (HR, 2.733; 95% CI, 1.122-6.657). Two-year overall survival in patients with or without HBV reactivation was 53.8% vs. 77.6% (p=0.025). Regarding the negative impact on clinical outcome, patients at "super high risk" of HBV reactivation, including those receiving more than eight cycles of R and having low LMR at diagnosis, may warrant first priority for antiviral prophylaxis.

Downregulation of signal transducer and activator of transcription 3 by sorafenib: A novel mechanism for hepatocellular carcinoma therapy

Hepatocellular carcinoma is one of the most common cancers worldwide, and a leading cause of cancer-related death. Owing to unsatisfactory clinical outcomes under the current standard of care, there is a need to search for and identify novel and potent therapeutic targets to improve patient outcomes. Sorafenib is the first and only approved targeted therapy for the treatment of hepatocellular carcinoma. Besides functioning as a multiple tyrosine kinase, sorafenib also acts via a kinase-independent mechanism to target signal transducer and activator of transcription 3 (STAT3) signaling in hepatocellular carcinoma cells. STAT3 is a key regulator of inflammation, cell survival, and tumorigenesis of liver cells, and the high percentage of hepatocellular carcinoma cells with constitutively active STAT3 justifies targeting it for the development of novel therapeutics. Sorafenib inactivates STAT3 and STAT3-related signaling by inducing a conformational change in and releasing the autoinhibition of Src homology region 2 domain-containing phosphatase-1. This phosphatase negatively regulates STAT3 activity, which leads to the subsequent apoptosis of cancer cells. The novel anti-cancer property of sorafenib will be discussed in this review, not only adding information regarding its mechanism of action but also providing an innovative approach for the development of cancer therapeutics in the future.

STAT3 mediates regorafenib-induced apoptosis in hepatocellular carcinoma

PURPOSE

Here, we aim to investigate the molecular mechanism of regorafenib and verify the potential druggable target for the treatment of hepatocellular carcinoma (HCC).

EXPERIMENTAL DESIGN

HCC cell lines (PLC5, HepG2, Hep3B, SK-Hep1, and HA59T) were used to investigate the in vitro effect of regorafenib. Phosphatase activity was analyzed in HCC cells and purified SHP-1 proteins. PLC5-bearing mice were used to test the therapeutic efficiency of 20 and 40 mg/kg/d treatment with regorafenib ([Formula: see text] mice). The clinical relevance of STAT3 signaling was investigated with 142 tumor samples from different patients with HCC. Descriptive statistical analysis was used to compare the baseline characteristics of patients and the expression of p-STAT3.

RESULTS

Regorafenib inhibited STAT3-related signaling in a dose-dependent manner and was a more potent inhibitor of STAT3 than sorafenib. Regorafenib increased SHP-1 phosphatase activity in purified SHP-1 protein directly. N-SH2 domain deletion and D61A mutants mimicking open-form SHP-1 partially abolished regorafenib-induced STAT3 inhibition and apoptosis. Importantly, a higher level of expression of STAT3 was found in patients with advanced clinical stages (P = 0.009) and poorly differentiated tumors (P = 0.035).

CONCLUSIONS

Regorafenib induced significant tumor inhibition by relieving the autoinhibited N-SH2 domain of SHP-1 directly and inhibiting p-STAT3 signals. STAT3 may be suitable as a prognostic marker of HCC development, and may be a druggable target for HCC-targeted therapy using regorafenib.

Systemic sclerosis and the risk of tuberculosis

OBJECTIVE

Pulmonary involvement is common in patients with systemic sclerosis (SSc), and this condition causes substantial morbidity and mortality. Disrupted immunity from the disease or associated medication may render such patients subject to tuberculosis (TB) infection. However, the relationship between SSc and TB has not yet been investigated.

METHODS

Using the Taiwan National Health Insurance Research Database, 838 patients with SSc diagnosed in Taiwan during 2000-2006 were identified and followed for emergence of TB infection. Incidence rate ratios (IRR) of TB compared to 8380 randomly selected age-, sex-, and comorbidity-matched controls without SSc were calculated. The Cox proportional hazards model was used for multivariate adjustment to identify independent risk factors for TB infection.

RESULTS

The risk of TB infection was higher in the SSc cohort than in controls (IRR 2.81, 95% CI 1.36-5.37; p = 0.004), particularly for pulmonary TB (IRR 2.53, 95% CI 1.08-5.30; p = 0.022). Other independent risk factors for TB infection in patients with SSc were age ≥ 60 years [hazard ratio (HR) 3.52, 95% CI 1.10-11.33; p = 0.035] and pulmonary hypertension (PH; HR 6.06, 95% CI 1.59-23.17; p = 0.008). Mortality did not differ for SSc patients with or without TB.

CONCLUSION

In this nationwide study, the incidence of TB infection was significantly higher among patients with SSc than in controls without SSc. Special care should be taken in managing patients with SSc who are at high risk for TB, especially those aged ≥ 60 years or who also have PH.

Atopic dermatitis and risk of ischemic stroke: a nationwide population-based study

BACKGROUND

Epidemiological studies have shown a strong association between systemic inflammatory diseases, particularly allergic diseases, and cardiovascular diseases. However, the relationship between atopic dermatitis (AD) and ischemic stroke remains unclear.

METHOD

The study identified 20,323 AD patients and 20,323 comorbidity-matched subjects between 2005 and 2008. The two cohorts were followed until 31 December 2009. Ischemic stroke and other cardiovascular events were determined.

RESULTS

During the follow-up period, 301 (1.48%) patients in the AD cohort and 228 (1.12%) matched subjects experienced ischemic stroke. After multivariate adjustment, patients with AD had a 1.33-fold (95% confidence interval (CI), 1.12-1.59; P = 0.001) increased incidence of ischemic stroke. Adjusted hazard ratios for the risk of ischemic stroke in patients with mild, moderate, and severe AD were 1.20 (95% CI, 1.00-1.45; P = 0.052), 1.64 (95% CI, 1.23-2.19; P = 0.001), and 1.71 (95% CI, 1.15-2.56; P = 0.008), respectively. The log-rank test showed a higher cumulative incidence of ischemic stroke in the severe AD group than in the moderate and mild AD groups during the follow-up period (P < 0.001).

CONCLUSIONS

AD may be an independent risk factor for ischemic stroke, and risk of ischemic stroke increases with AD severity.

Cancer risk among patients with coal workers' pneumoconiosis in Taiwan: a nationwide population-based study

This study is aimed to evaluate the cancer risk among patients with coal workers' pneumoconiosis (CWP) using a nationwide population-based dataset. Patients without previous cancer who had been diagnosed with CWP and followed-up for more than 1 year between 1997 and 2006 were recruited from the Taiwan National Health Insurance database. Standardized incidence ratios (SIRs) of cancers in CWP patients were calculated and compared to the cancer incidence in the general population. Risk factors for cancer development were also analyzed. After a median follow-up of 9.68 years, 954 cancers developed among 8,051 recruited CWP patients, with a follow-up of 69,398 person-years. The SIR for all cancers was 1.12 [95% confidence interval (CI) 1.04-1.18]. Males older than 80 years had a SIR of 1.27 (95% CI: 1.06-1.51). The SIRs of esophageal (1.76, 95% CI: 1.24-2.44), gastric (1.42, 95% CI: 1.13-1.76), liver and biliary tract (1.18, 95% CI: 1.01-1.37) and lung and mediastinal (1.45, 95% CI: 1.26-1.66) cancers were significantly higher in the CWP group than in the general population. Multivariate analysis showed that age ≥ 60 years [hazard ratio (HR) 1.70, 95% CI: 1.41-2.05), male gender (HR = 1.79, 95% CI: 1.44-2.23) and liver cirrhosis (HR = 3.99, 95% CI: 2.89-5.51) were significant predictors of cancer development in patients with CWP. We concluded that patients with CWP, especially elderly males, were at increased risk of cancer. Age, male gender and liver cirrhosis were independent risk factors for cancer development.

Effect of age and biological subtype on the risk and timing of brain metastasis in breast cancer patients

BACKGROUND

Brain metastasis is a major complication of breast cancer. This study aimed to analyze the effect of age and biological subtype on the risk and timing of brain metastasis in breast cancer patients.

PATIENTS AND METHODS

We identified subtypes of invasive ductal carcinoma of the breast by determining estrogen receptor, progesterone receptor and HER2 status. Time to brain metastasis according to age and cancer subtype was analyzed by Cox proportional hazard analysis.

RESULTS

Of the 2248 eligible patients, 164 (7.3%) developed brain metastasis over a median follow-up of 54.2 months. Age 35 or younger, HER2-enriched subtype, and triple-negative breast cancer were significant risk factors of brain metastasis. Among patients aged 35 or younger, the risk of brain metastasis was independent of biological subtype (P = 0.507). Among patients aged 36-59 or >60 years, those with triple-negative or HER2-enriched subtypes had consistently increased risk of brain metastasis, as compared with those with luminal A tumors. Patients with luminal B tumors had higher risk of brain metastasis than luminal A only in patients >60 years.

CONCLUSIONS

Breast cancer subtypes are associated with differing risks of brain metastasis among different age groups. Patients age 35 or younger are particularly at risk of brain metastasis independent of biological subtype.

The risk of cancer in patients with benign anal lesions: a nationwide population-based study

OBJECTIVE

To evaluate the risk of cancer among patients diagnosed with hemorrhoids and benign anal inflammatory lesions.

METHODS

A population-based, retrospective cohort study was conducted that included patients diagnosed with hemorrhoids or benign inflammatory anal lesions (eg, anal fissure, fistula, and perianal abscesses) that were registered in the National Health Insurance Research Database in Taiwan between January 1, 2000 and December 31, 2010. Standardized incidence ratios (SIRs) were calculated to compare the cancer incidence of these patients to the general population.

RESULTS

During a median observation period of 6.23 years, 3080 cancers developed among 70,513 hemorrhoid patients, with a follow-up period of 438,425.6 person-years, entailing the SIR of 1.52 (95% confidence interval [CI], 1.47-1.58). Increased cancer risk (SIR 1.16; 95% CI, 1.11-1.21) was still noted even after excluding the first year of observation. Significant long-term risk for colorectal cancer (SIR 1.50; 95% CI, 1.35-1.66) and prostate cancer (SIR 1.40; 95% CI, 1.17-1.66) was observed after corrections were made for multiple comparisons. In contrast, there was no remarkable increase in cancer risk for patients with inflammatory anal lesions when cancers detected within the first year of diagnosis were excluded.

CONCLUSION

The presence of hemorrhoids is associated significantly with a long-term risk of developing colorectal cancer or prostate cancer. In contrast, benign inflammatory anal lesions do not appear to increase the risk of malignancy.

Absolute lymphocyte count predicts response to rituximab-containing salvage treatment for relapsed/refractory B-cell non-Hodgkin's lymphoma with prior rituximab exposure

BACKGROUND

Rituximab-containing salvage chemotherapy has shown promising efficacy in patients with relapsed/refractory B-cell non-Hodgkin's lymphoma (NHL). The aim of this study was to examine the efficacy of rituximab-containing treatment in patients with B-cell NHL who developed relapsed or refractory disease after prior rituximab use and to explore the predictive factors of response using this approach.

METHODS

Patients with relapsed/refractory B-cell NHL who received rituximab-containing salvage treatment after failing first-line rituximab-combining chemotherapy were enrolled in this retrospective study. The characteristics of the patients were collected and analyzed. Logistic regression analysis was used for determining predictive factors of response to rituximab-containing salvage treatment.

RESULTS

A total of 68 patients were enrolled in this study and the overall response rate to rituximab-containing salvage treatment was 61.7%. The median event-free survival and overall survival with rituximab-containing salvage treatment was 11.3 and 21.73 months, respectively. Results of a multivariate analysis showed high absolute lymphocyte count at the time of rituximab-containing salvage treatment [(ALC-R), ALC-R ≥ 1000/UL, p = 0.003)], which was the only independent factor predicting response to rituximab-containing salvage treatment.

CONCLUSION

Our study results show that for patients with relapsed/refractory B-cell NHL, rituximab-containing salvage treatment is feasible and generally tolerable. A high ALC-R value was significantly associated with a better response to this treatment.

Incidence and risk of mood disorders in patients with breast cancers in Taiwan: a nationwide population-based study

OBJECTIVE

The objective of this study is to assess the incidence and risk of mood disorders, including major depression, anxiety, and bipolar disorders, in Taiwanese patients after the diagnosis of breast cancer compared with a matched cohort.

METHODS

From January 2000 to December 2005, 26,629 newly diagnosed breast cancer patients were enrolled by the Taiwan National Health Insurance program database. The control cohort was selected randomly from 1,000,000 National Health Insurance beneficiaries from a population of 21,400,826 enrolled throughout Taiwan. Each patient was matched with one subject without breast cancer by age, sex, and presence of comorbidities with the same diagnosis index date. The diagnosis of mood disorders was defined by compatible International Classification of Diseases, 9th revision, clinical modification codes plus the prescription of antidepressants for at least 30 days.

RESULTS

The overall incidence rate ratio of mood disorders was 1.33 (95% CI 1.28-1.39, p < 0.001) in the breast cancer cohort compared with the matched cohort. The incidence rate ratios for specific mood disorders were 2.06 for bipolar disorder (95% CI 1.37-3.15 p = 0.0003), 1.94 for major depressive disorder (95% CI 1.76-2.13 p < 0.001), and 1.22 for anxiety (95% CI 1.16-1.27 p < 0.001). Independent risk factors for developing mood disorders included breast cancer, as well as age, hypertension, chronic obstructive pulmonary disease, autoimmune disease, ischemic heart disease, and cerebrovascular disease.

CONCLUSIONS

Breast cancer is a prominent risk factor for mood disorders, including major depressive disorder, anxiety, and bipolar disorder. The impact is most potent in the first year after diagnosis. Psychological support is a critical issue in these patients.

The risk of cancer in patients with generalized anxiety disorder: a nationwide population-based study

OBJECTIVE

To evaluate the risk of cancer among patients with generalized anxiety disorder (GAD) in a nationwide population-based dataset.

METHODS

We recruited newly-diagnosed GAD patients aged 20 years or older without antecedent cancer from the Taiwan National Health Insurance Research database between 2000-2010. Standardized incidence ratios (SIRs) of cancers were calculated in GAD patients, and the subgroup of GAD patients diagnosed by psychiatric specialists.

RESULTS

A total of 559 cancers developed among 19,793 GAD patients with a follow-up of 89,485 person-years (median follow-up of 4.34 years), leading to a significantly increased SIR of 1.14 [95% confidence interval (CI) 1.05-1.24]. Male GAD patients had a significantly increased SIR overall (1.30, 95% CI 1.15-1.46) and for lung and prostate cancer (1.77, 95% CI 1.33-2.30 and 2.17, 95% CI 1.56-2.93, respectively). Patients over 80 years of age also had a significantly increased SIR (1.56, 95% CI 1.25-1.92), especially in males. However, psychiatrist-diagnosed GAD patients did not show increased cancer risk relative to the general population, perhaps due to having fewer physical comorbidities than non-psychiatrist-diagnosed GAD patients.

CONCLUSION

This study found that overall cancer risk is elevated among patients with GAD. The risk of lung and prostate cancer also increased in male patients with GAD. This increased cancer risk may be due to physical comorbidities and surveillance bias. Further prospective study is necessary to confirm these findings.

Efficient formulation of the force distribution equations for general tree-structured robotic mechanisms with a mobile base

In this paper, an efficient and systematic formulation of the force distribution equations for general tree-structured robotic mechanisms is presented. The applicable platforms include not only systems with star topologies, such as walking machines that have multiple legs with a single body but also general tree-structured mechanisms, such as variably configured wheeled vehicles having multiple modules. The force balance equations that govern the relationship between the contact forces and the resultant inertial forces/moments of the vehicle will be derived through a recursive and computationally efficient algorithm. Also, the joint torque constraints that specify the joint actuator limits, and contact friction constraints that may be used to avoid slippage and maintain contact, are efficiently incorporated in the formulation. Based on this formulation, several standard optimization techniques, such as linear programming or quadratic programming, can be applied to obtain the solution. An algorithm summarizing the results developed, and suitable for computer implementation, is included. The algorithm has been applied to an n-module actively articulated wheeled vehicle, and the computational cost evaluated. The efficiency of the algorithm is demonstrated with results showing real-time execution on a Pentium PC.

The conditional probabilities of survival in patients with anaplastic astrocytoma or glioblastoma multiforme

BACKGROUND

By the use of conditional probabilities of survival, we studied the yearly survival rates for individual tumor survivors.

METHODS

Conditional survival rate was estimated in 114 consecutive patients with anaplastic astrocytoma or glioblastoma multiforme. Conditional probabilities of surviving some years given survival to a specific period of time after craniotomy and 95% confidence intervals were calculated in the individual tumor survivors.

RESULTS

The estimated median survival was 30 months for 45 patients with anaplastic astrocytoma and 12 months for 69 patients with glioblastoma multiforme. The conditional probabilities of surviving next one year given survival to 1 year, 2 years, 3 years, 4 years, or 5 years after craniotomy for anaplastic astrocytoma were 86.2%, 75.0%, 85.9%, 77.8%, or 85.7%, respectively; for glioblastoma multiforme 64.8%, 58.7%, 85.7%, 80.0%, or 75.0%, respectively. The conditional probability of surviving to 5 years given survival to 2 years after craniotomy for anaplastic astrocytoma, i.e., surviving an additional 3 years, was 50.1%, which was better than observed 5-year survival rate (28.6%); for glioblastoma multiforme it was 40.2%, which also was better than observed 5-year survival rate (12.4%).

CONCLUSIONS

The conditional probability of survival was a good method to clinically predict yearly survival rate for individual tumor survivors. In addition, the method can estimate the probabilities of surviving next some years given survival to a specific period of time after craniotomy. It also showed a more encouraging result than observed survival rate in patients with supratentorial malignant astrocytomas.

Epitope mapping of factor VIII inhibitor antibodies of Chinese origin

Epitopes recognized by factor VIII (FVIII) inhibitors of Chinese origin were analysed by immunoblotting with full-length recombinant FVIII (rFVIII), thrombin-activated FVIII (FVIIIa) and 16 FVIII fusion proteins synthesized by bacteria. Twenty-eight patients, 12 with haemophilia A and 16 with autoimmune diseases, were recruited. Antibodies from 22 patients showed reactivity with rFVIII, 20 with FVIIIa, and one reacted only with FVIII fusion proteins. Of these 22 cases, most were reactive with A2-a2 and A3-C1-C2 of FVIII(a). Of the nine cases that depicted binding to the fusion proteins, three were reactive with the A domains, three with only the B domain, and the other three with both the A and B (or C) domains. An epitope for a neutralizing antibody of a haemophilia A patient, designated TWN-112, was localized to residues 323-390, specified by FVIII fusion proteins. The same epitope also appeared on an FVIII-expression phage library screening. Immunoabsorption of antibodies from TWN-112 with the epitope reduced the neutralizing activity of the inhibitor by 33%. The incidence of a1 of FVIII is higher, and that of a3 is lower, than previously reported. Two novel epitopes, reported for the first time in this paper, were localized on the 8B2 (amino acid residues 1022-1204) and 8A2(V) (residues 673-740) fusion proteins. These two epitopes were able to reduce inhibitory antibody activity by 24% and 25% respectively. Changes of FVIII fragment specificity were also observed in one of six patients for whom multiple samples, collected at different times, were available. Our initial finding showed that the FVIII inhibitors in these Chinese patients shared epitopes with those of patients from very different genetic backgrounds, suggesting a common mechanism for the development of FVIII inhibitors.