Premila D. Leiphrakpam

Preoperative Nomogram to Predict Risk of Perioperative Mortality Following Pancreatic Resections for Malignancy

IntroductionThe majority of pancreatic resections for malignancy are performed in older patients with major comorbidities. The aim of this study was to develop a preoperative nomogram based on the presence of comorbidities to predict risk of perioperative mortality.Materials and MethodsThe National Inpatient Sample database was queried to identify patients that underwent pancreatectomy for malignancy. The preoperative comorbidities identified as predictors were used, and a nomogram was created. Sample A (2000–2004) was utilized to develop the model, and sample B (2005) was utilized to validate this model.ResultsThe overall actual observed perioperative mortality rate for samples A and B was 6.3% and 5.2%, respectively. The mean total points calculated for sample A by the nomogram was 131.7 that translates to a nomogram-predicted mortality rate of 4.9%, which is similar to the actual mortality. The mean total points for sample B was 128.1, which translates to a nomogram-predicted mortality rate of 4.6%. The similarity of mortality rates as predicted by the nomogram and a concordance index of 0.76 shows good agreement between the data and the nomogram.ConclusionThis preoperative nomogram has been shown to accurately predict the risk of perioperative mortality following pancreatectomy for malignancy.

Akt inhibitor MK-2206 promotes anti-tumor activity and cell death by modulation of AIF and Ezrin in colorectal cancer

BackgroundThere is extensive evidence for the role of aberrant cell survival signaling mechanisms in cancer progression and metastasis. Akt is a major component of cell survival-signaling mechanisms in several types of cancer. It has been shown that activated Akt stabilizes XIAP by S87 phosphorylation leading to survivin/XIAP complex formation, caspase inhibition and cytoprotection of cancer cells. We have reported that TGFβ/PKA/PP2A-mediated tumor suppressor signaling regulates Akt phosphorylation in association with the dissociation of survivin/XIAP complexes leading to inhibition of stress-dependent induction of cell survival.MethodsIGF1R-dependent colon cancer cells (GEO and CBS) were used for the study. Effects on cell proliferation and cell death were determined in the presence of MK-2206. Xenograft studies were performed to determine the effect of MK-2206 on tumor volume. The effect on various cell death markers such as XIAP, survivin, AIF, Ezrin, pEzrin was determined by western blot analysis. Graph pad 5.0 was used for statistical analysis. P < 0.05 was considered significant.ResultsWe characterized the mechanisms by which a novel Akt kinase inhibitor MK-2206 induced cell death in IGF1R-dependent colorectal cancer (CRC) cells with upregulated PI3K/Akt signaling in response to IGF1R activation. MK-2206 treatment generated a significant reduction in tumor growth in vivo and promoted cell death through two mechanisms. This is the first report demonstrating that Akt inactivation by MK-2206 leads to induction of and mitochondria-to-nuclear localization of the Apoptosis Inducing Factor (AIF), which is involved in caspase-independent cell death. We also observed that exposure to MK-2206 dephosphorylated Ezrin at the T567 site leading to the disruption of Akt-pEzrin-XIAP cell survival signaling. Ezrin phosphorylation at this site has been associated with malignant progression in solid tumors.ConclusionThe identification of these 2 novel mechanisms leading to induction of cell death indicates MK-2206 might be a potential clinical candidate for therapeutic targeting of the subset of IGF1R-dependent cancers in CRC.

Ezrin expression and cell survival regulation in colorectal cancer.

Colorectal cancer (CRC) is the second largest cause of cancer deaths in the United States. A key barrier that prevents better outcomes for this type of cancer as well as other solid tumors is the lack of effective therapies against the metastatic disease. Thus there is an urgent need to fill this gap in cancer therapy. We utilized a 2D-DIGE proteomics approach to identify and characterize proteins that are differentially regulated between primary colon tumor and liver metastatic deposits of the IGF1R-dependent GEO human CRC xenograft, orthotopically implanted in athymic nude mice that may serve as potential therapeutic targets against CRC metastasis. We observed increased expression of ezrin in liver metastasis in comparison to the primary colonic tumor. Increased ezrin expression was further confirmed by western blot and microarray analyses. Ezrin, a cytoskeletal protein belonging to Ezrin-Radixin-Moesin (ERM) family plays important roles in cell motility, invasion and metastasis. However, its exact function in colorectal cancer is not well characterized. Establishment of advanced GEO cell lines with enhanced liver-metastasizing ability showed a significant increase in ezrin expression in liver metastasis. Increased phosphorylation of ezrin at the T567 site (termed here as p-ezrin T567) was observed in liver metastasis. IHC studies of human CRC patient specimens showed an increased expression of p-ezrin T567 in liver metastasis compared to the primary tumors of the same patient. Ezrin modulation by siRNA, inhibitors and T567A/D point mutations significantly downregulated inhibitors of apoptosis (IAP) proteins XIAP and survivin that have been linked to increased aberrant cell survival and metastasis and increased cell death. Inhibition of the IGF1R signaling pathway by humanized recombinant IGF1R monoclonal antibody MK-0646 in athymic mouse subcutaneous xenografts resulted in inhibition of p-ezrin T567 indicating ezrin signaling is downstream of the IGF1R signaling pathway. We identified increased expression of p-ezrin T567 in CRC liver metastasis in both orthotopically implanted GEO tumors as well as human patient specimens. We report for the first time that p-ezrin T567 is downstream of the IGF1R signaling and demonstrate that ezrin regulates cell survival through survivin/XIAP modulation.

National trends in discharge disposition after hepatic resection for malignancy.

BACKGROUND There is a paucity of data on the trends in discharge disposition for patients undergoing hepatic resection for malignancy. AIM To analyse the national trends in discharge disposition after hepatic resection for malignancy. METHODS The National Inpatient Sample (NIS) database was queried (1993 to 2005) to identify patients that underwent hepatic resection for malignancy and analyse the discharge status (home, home health or rehabilitation/skilled facility). RESULTS A weighted total of 74,520 patients underwent hepatic resection of whom, 53,770 patients had a principal diagnosis of malignancy. The overall mortality improved from 6.3% to 3.4%. After excluding patients that died in the post-operative period and those with incomplete discharge status, 45,583 patients were included. The proportion of patients that had acute care needs preventing them from being discharged home without assistance increased from 10.9% in 1993 to 19.5% in 2005. While there was an increase in the number of patients discharged to home health care during this time (8.9% to 13.8%), there was a larger increase in the proportion of patients that were discharged to a rehabilitation or skilled nursing facility (2% to 5.7%). Despite a decrease in the mortality rates, there was no improvement in rate of patients discharged home without assistance over the period of the study. CONCLUSIONS The results of the present study demonstrate that after hepatic resection, a significant proportion of patients will need assistance upon discharge. This information needs to be included in patient counselling during pre-operative risk and benefit assessment.

In vivo analysis of insulin-like growth factor type 1 receptor humanized monoclonal antibody MK-0646 and small molecule kinase inhibitor OSI-906 in colorectal cancer

The development and characterization of effective anticancer drugs against colorectal cancer (CRC) is of urgent need since it is the second most common cause of cancer death. The study was designed to evaluate the effects of two IGF-1R antagonists, MK-0646, a recombinant fully humanized monoclonal antibody and OSI-906, a small molecule tyrosine kinase inhibitor on CRC cells. Xenograft study was performed on IGF-1R-dependent CRC cell lines for analyzing the antitumor activity of MK-0646 and OSI-906. Tumor proliferation and apoptosis were assessed using Ki67 and TUNEL assays, respectively. We also performed in vitro characterization of MK-0646 and OSI-906 treatment on CRC cells to identify mechanisms associated with drug-induced cell death. Exposure of the GEO and CBS tumor xenografts to MK-0646 or OSI-906 led to a decrease in tumor growth. TUNEL analysis showed an increase of approximately 45–55% in apoptotic cells in both MK-0646 and OSI-906 treated tumor samples. We report the novel finding that treatment with IGF-1R antagonists led to downregulation of X-linked inhibitor of apoptosis (XIAP) protein involved in cell survival and inhibition of cell death. In conclusion, IGF-1R antagonists (MK-0646 and OSI-906) demonstrated single agent inhibition of subcutaneous CRC xenograft growth. This was coupled to pro-apoptotic effects resulting in downregulation of XIAP and inhibition of cell survival. We report a novel mechanism by which MK-0646 and OSI-906 elicits cell death in vivo and in vitro. Moreover, these results indicate that MK-0646 and OSI-906 may be potential anticancer candidates for the treatment of patients with IGF-1R-dependent CRC.

Differential PKA activation and AKAP association determines cell fate in cancer cells

Background The dependence of malignant properties of colorectal cancer (CRC) cells on IGF1R signaling has been demonstrated and several IGF1R antagonists are currently in clinical trials. Recently, we identified a novel pathway in which cAMP independent PKA activation by TGFβ signaling resulted in the destabilization of survivin/XIAP complex leading to increased cell death. In this study, we evaluated the effect of IGF1R inhibition or activation on PKA activation and its downstream cell survival signaling mechanisms. Methods Small molecule IGF1R kinase inhibitor OSI-906 was used to test the effect of IGF1R inhibition on PKA activation, AKAP association and its downstream cell survival signaling. In a complementary approach, ligand mediated activation of IGF1R was performed and AKAP/PKA signaling was analyzed for their downstream survival effects. Results We demonstrate that the inhibition of IGF1R in the IGF1R-dependent CRC subset generates cell death through a novel mechanism involving TGFβ stimulated cAMP independent PKA activity that leads to disruption of cell survival by survivin/XIAP mediated inhibition of caspase activity. Importantly, ligand mediated activation of the IGF1R in CRC cells results in the generation of cAMP dependent PKA activity that functions in cell survival by inhibiting caspase activity. Therefore, this subset of CRC demonstrates 2 opposing pathways organized by 2 different AKAPs in the cytoplasm that both utilize activation of PKA in a manner that leads to different outcomes with respect to life and death. The cAMP independent PKA activation pathway is dependent upon mitochondrial AKAP149 for its apoptotic functions. In contrast, Praja2 (Pja2), an AKAP-like E3 ligase protein was identified as a key element in controlling cAMP dependent PKA activity and pro-survival signaling. Genetic manipulation of AKAP149 and Praja2 using siRNA KD had opposing effects on PKA activity and survivin/XIAP regulation. Conclusions We had identified 2 cytoplasmic pathways dependent upon the same enzymatic activity with opposite effects on cell fate in terms of life and death. Understanding the specific mechanistic functions of IGF1R with respect to determining the PKA survival functions would have potential for impact upon the development of new therapeutic strategies by exploiting the IGF1R/cAMP-PKA survival signaling in cancer.

Establishment and Validation of an Orthotopic Metastatic Mouse Model of Colorectal Cancer

Metastases are largely responsible for cancer deaths in solid tumors due to the lack of effective therapies against disseminated disease, and there is an urgent need to fill this gap. This study demonstrates an orthotopic colorectal cancer (CRC) mouse model system to develop spontaneous metastasis in vivo and compare its reproducibility against human CRC. IGF1R-dependent GEO human CRC cells were used to study metastatic colonization using orthotopic transplantation procedures and demonstrated robust liver metastasis. Cell proliferation assays were performed both in the orthotopic primary colon and liver metastatic tumors, and human CRC patients specimen and similar patterns in H&E and Ki67 staining were observed between the orthotopically generated primary and liver metastatic tumors and human CRC specimens. Microarray analysis was performed to generate gene signatures, compared with deposited human CRC gene expression data sets, analyzed by Oncomine, and revealed similarity in gene signatures with increased aggressive markers expression associated with CRC in orthotopically generated liver metastasis. Thus, we have developed an orthotopic mouse model that reproduces human CRC metastasis. This model system can be effective in developing new therapeutic strategies against disseminated disease and could be implemented for identifying genes that regulate the development and/or maintenance of established metastasis.

TGFβ and IGF1R signaling activates protein kinase A through differential regulation of ezrin phosphorylation in colon cancer cells

Aberrant cell survival plays a critical role in cancer progression and metastasis. We have previously shown that ezrin, a cAMP-dependent protein kinase A–anchoring protein (AKAP), is up-regulated in colorectal cancer (CRC) liver metastasis. Phosphorylation of ezrin at Thr-567 activates ezrin and plays an important role in CRC cell survival associated with XIAP and survivin up-regulation. In this study, we demonstrate that in FET and GEO colon cancer cells, knockdown of ezrin expression or inhibition of ezrin phosphorylation at Thr-567 increases apoptosis through protein kinase A (PKA) activation in a cAMP-independent manner. Transforming growth factor (TGF) β signaling inhibits ezrin phosphorylation in a Smad3-dependent and Smad2-independent manner and regulates pro-apoptotic function through ezrin-mediated PKA activation. On the other hand, ezrin phosphorylation at Thr-567 by insulin-like growth factor 1 receptor (IGF1R) signaling leads to cAMP-dependent PKA activation and enhances cell survival. Further studies indicate that phosphorylated ezrin forms a complex with PKA RII, and dephosphorylated ezrin dissociates from the complex and facilitates the association of PKA RII with AKAP149, both of which activate PKA yet lead to either cell survival or apoptosis. Thus, our studies reveal a novel mechanism of differential PKA activation mediated by TGFβ and IGF1R signaling through regulation of ezrin phosphorylation in CRC, resulting in different cell fates. This is of significance because TGFβ and IGF1R signaling pathways are well-characterized tumor suppressor and oncogenic pathways, respectively, with important roles in CRC tumorigenesis and metastasis. Our studies indicate that they cross-talk and antagonize each others function through regulation of ezrin activation. Therefore, ezrin may be a potential therapeutic target in CRC.

Abstract 4563: Role of ezrin in PKA dependent colorectal cancer cell fate

Introduction: Metastasis is the main cause of cancer related death in CRC. However, the molecular basis of CRC metastasis is poorly understood. Ezrin is a known cAMP dependent AKAP. We have found ezrin hyperphosphorylation at T567 is critical for CRC cell survival. In this study we evaluated the dependency of PKA activation with ezrin phosphorylation at T567 on its downstream cell survival mechanisms. Methods: Small molecule ezrin kinase inhibitor NSC668394 was used to test the effect of inhibition of ezrinT567 phosphorylation on PKA activation and its downstream cell survival signaling. A genetic knockdown approach was utilized to further confirm the result. In another approach, growth factor mediated activation of ezrin T567 phosphorylation was performed and ezrin/PKA signaling was then analyzed for its downstream cell survival effects. To further confirm the findings ezrin phospho-mimetic (T567D) and phospho-deficient (T567A) mutants were generated through site directed mutation approaches. Results: We demonstrated that dephosphorylation of ezrin at T567 activates PKA in a cAMP independent manner and leads to CRC cell death through inhibition of XIAP and survivin. Moreover, the stable knockdown of ezrin showed similar result. Interestingly, ligand mediated ezrin hyperphosphorylation at T567 has the opposite effect in which there is cAMP dependent PKA activation leading to CRC survival through upregulation of XIAP and survivin. This was further confirmed with ezrin T567 phospho-mimetic and phospho-deficient mutants which demonstrate PKA activation by cAMP dependent and independent mechanisms respectively leading to different CRC cell fates. Therefore, ezrin signaling demonstrated two opposing pathways in which both requires activation of PKA and yet result in different CRC cell fates by regulating XIAP and survivin expression. Conclusions: Two different ezrin signaling dependent pathways were identified which are dependent on the same enzymatic activity but with opposite effects on CRC cell fates. Therefore, ezrin might be a novel target that could be utilized for the development of new therapeutic strategies and further understanding the mechanism of ezrin/cAMP-PKA activation and its role in CRC cell survival could have potential impact for treatment of distant metastasis in CRC. Citation Format: Premila Leiphrakpam, Michael G. Brattain. Role of ezrin in PKA dependent colorectal cancer cell fate. [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 4563.

Abstract 3887: The expression and clinical significance of Ezrin in colorectal cancer metastasis.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Introduction: Colorectal Cancer(CRC) metastasis to distant organ sites is a major cause of CRC-related death. To date, there are no effective anti-metastatic therapies available. The purpose of this study was to use a proteomics-based approach to identify and characterize molecular targets associated with CRC metastasis. Methods: GFP-labeled GEO human CRC cells were used to generate subcutaneous xenografts in BALB/c nude mice, which in turn were orthotopically implanted. This model allows for reproducible quantitative analysis of metastasis to liver and lungs. Primary and liver metastases were collected and a 2D-DIGE proteomics approach was used to characterize the global protein expression in the primary tumors and the corresponding liver metastases. Tissues were labeled with CyDye DIGE fluors and analyzed on a single multiplexed gel. DeCyder “in-gel” analysis software was used to compare all protein spots and protein expression ratios between the primary tumor and liver metastasis were generated. Differential spots were selected, in-gel digested and peptide mass fingerprints were obtained. Gene microarray analysis using the Illumina platform was also performed on primary and metastatic tumors. Westerns were performed to confirm protein expression. Survival signaling in GEO cells is dependent on the IGF1R pathway and thus, an IGF1R monoclonal antibody, MK-0646 was used to assess downstream effects. Results: Differential expression of Ezrin was identified, as it was increased in liver metastases compared to primary tumors. This was validated by microarrays and westerns. Ezrin, a protein belonging to the Ezrin-Radixin-Moesin (ERM) family plays important roles in cell motility, invasion, tumor progression and metastasis. We also observed that T567 hyperphosphorylation of Ezrin was correlated to CRC metastasis by western blot analysis of primary tumor with liver metastases. This was further confirmed by IHC on human CRC patient specimens. Moreover, inhibition of the IGF-1R signaling pathway by mAb MK-0646 in mouse GEO CRC subcutaneous xenografts resulted in inhibition of Ezrin phosphorylation at T567, indicating that Ezrin signaling is downstream of the IGF-1R signaling pathway. SiRNA knockdown of Ezrin significantly downregulated XIAP, which is a metastasis gene in this model. Therefore, XIAP is downstream of IGF-1R-Ezrin signaling. Conclusions: Using a proteomics approach, we identified ezrin as a potential biomarker for metastasis in CRC. We show for the first time that Ezrin activation at T567 is downstream of the IGF-1R signaling pathway and contributes to cell survival in CRC metastasis. Thus, ezrin might be a novel target that could be utilized for the development of effective anti-metastatic therapies against CRC. Citation Format: Premila Devi Leiphrakpam, Ashwani Rajput, Michael G. Brattain, Sanjib Chowdhury. The expression and clinical significance of Ezrin in colorectal cancer metastasis. [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 3887. doi:10.1158/1538-7445.AM2013-3887