Multimodality Management of "Borderline Resectable" Pancreatic Neuroendocrine Tumors: Report of a Single-Institution Experience.

BACKGROUND: Pancreatic neuroendocrine tumors (PanNETs) constitute approximately 3% of pancreatic neoplasms. Like patients with pancreatic ductal adenocarcinoma (PDAC), some of these patients present with "borderline resectable disease." For these patients, an optimal treatment approach is lacking. We report our institution's experience with borderline resectable PanNETs using multimodality treatment. METHODS: We identified patients with borderline resectable PanNETs who had received neoadjuvant therapy at our institution between 2000 and 2013. The definition of borderline resectability was based on National Comprehensive Cancer Network criteria for PDAC. Neoadjuvant regimen, radiographic response, pathologic response, surgical margins, nodal retrieval, number of positive nodes, and recurrence were documented. Statistics were descriptive. RESULTS: Of 112 patients who underwent surgical resection for PanNETs during the study period, 23 received neoadjuvant therapy, 6 of whom met all inclusion criteria and had borderline resectable disease. These 6 patients received at least 1 cycle of temozolomide and capecitabine, with 3 also receiving radiation. All had radiographic evidence of treatment response. Four (67%) had negative-margin resections. Four patients had histologic evidence of a moderate response. Follow-up (3.0-4.3 years) indicated that all patients were alive, with 5/6 free of disease (1 patient with metastatic disease still on treatment without progression). CONCLUSIONS: A multimodality treatment strategy (neoadjuvant temozolomide and capecitabine ± radiation) can be successfully applied to patients with PanNETs who meet NCCN borderline resectable criteria for PDAC. To our knowledge, this is the first report of the use of a multimodality protocol in the treatment of patients with borderline resectable PanNETs.

Liver Label Retaining Cancer Cells Are Relatively Resistant to the Reported Anti-Cancer Stem Cell Drug Metformin.

BACKGROUND & AIMS: Recently, we reported that liver Label Retaining Cancer Cells (LRCC) can initiate tumors with only 10 cells and are relatively resistant to the targeted drug Sorafenib, a standard of practice in advanced hepatocellular carcinoma (HCC). LRCC are the only cancer stem cells (CSC) isolated alive according to a stem cell fundamental function, asymmetric cell division. Metformin has been reported to preferentially target many other types of CSC of different organs, including liver. It's important to know if LRCC, a novel class of CSC, are relatively resistant to metformin, unlike other types of CSC. As metformin inhibits the Sorafenib-Target-Protein (STP) PI3K, and LRCC are newly described CSC, we undertook this study to test the effects of Metformin on Sorafenib-treated HCC and HCC-derived-LRCC. METHODS: We tested various STP levels and phosphorylation status, associated genes' expression, proliferation, viability, toxicity, and apoptosis profiles, before and after treatment with Sorafenib with/without Metformin. RESULTS: Metformin enhances the effects of Sorafenib on HCC, and significantly decreased viability/proliferation of HCC cells. This insulin-independent effect was associated with inhibition of multiple STPs (PKC, ERK, JNK and AKT). However, Metformin increased the relative proportion of LRCCs. Comparing LRCC vs. non-LRCC, this effect was associated with improved toxicity and apoptosis profiles, down-regulation of cell death genes and up-regulation of cell proliferation and survival genes in LRCC. Concomitantly, Metformin up-regulated pluripotency, Wnt, Notch and SHH pathways genes in LRCC vs. non-LRCC. CONCLUSIONS: Metformin and Sorafenib have enhanced anti-cancer effects. However, in contradistinction to reports on other types of CSC, Metformin is less effective against HCC-derived-CSC LRCC. Our results suggest that combining Metformin with Sorafenib may be able to repress the bulk of tumor cells, but as with other anti-cancer drugs, may leave LRCC behind leading to cancer recurrence. Therefore, liver LRCC, unlike other types of CSC, are relatively resistant to the reported anti-cancer stem cell drug metformin. This is the first report that there is a type of CSC that is not relatively resistant to the CSC-targeting drug. Our findings suggest that a drug targeting LRCC may be critically needed to target CSC and prevent cancer recurrence. These may significantly contribute to the understanding of Metformin's anti-cancer effects and the development of novel drugs targeting the relatively resistant LRCC.

Effect of Metformin Use on Survival in Resectable Pancreatic Cancer: A Single-Institution Experience and Review of the Literature.

Observational studies have demonstrated that metformin use in diabetic patients is associated with reduced cancer incidence and mortality. Here, we aimed to determine whether metformin use was associated with improved survival in patients with resected pancreatic cancer. All patients with diabetes who underwent resection for pancreatic adenocarcinoma between 12/1/1986 and 4/30/2013 at our institution were categorized by metformin use. Survival analysis was done using the Kaplan-Meier method, with log-rank test and Cox proportional hazards multivariable regression models. For analyses of our data and the only other published study, we used Meta-Analysis version 2.2. We identified 44 pancreatic cancer patients with diabetes who underwent resection of the primary tumor (19 with ongoing metformin use, 25 never used metformin). There were no significant differences in major clinical and demographic characteristics between metformin and non-metformin users. Metformin users had a better median survival than nonusers, but the difference was not statistically significant (35.3 versus 20.2 months; P = 0.3875). The estimated 2-, 3-, and 5-year survival rates for non-metformin users were 42%, 28%, and 14%, respectively. Metformin users fared better with corresponding rates of 68%, 34%, and 34%, respectively. In our literature review, which included 111 patients from the two studies (46 metformin users and 65 non-users), overall hazard ratio was 0.668 (95% CI 0.397-1.125), with P = 0.129. Metformin use was associated with improved survival outcomes in patients with resected pancreatic cancer, but the difference was not statistically significant. The potential benefit of metformin should be investigated in adequately powered prospective studies.

Wnt and the cancer niche: paracrine interactions with gastrointestinal cancer cells undergoing asymmetric cell division.

OBJECTIVE: Stem-like cancer cells contribute to cancer initiation and maintenance. Stem cells can self-renew by asymmetric cell division (ACD). ACD with non-random chromosomal cosegregation (ACD-NRCC) is one possible self-renewal mechanism. There is a paucity of evidence supporting ACD-NRCC in human cancer. Our aim was to investigate ACD-NRCC and its potential interactions with the cancer niche (microenvironment) in gastrointestinal cancers. DESIGN: We used DNA double and single labeling approaches with FACS to isolate live cells undergoing ACD-NRCC. RESULTS: Gastrointestinal cancers contain rare subpopulations of cells capable of ACD-NRCC. ACD-NRCC was detected preferentially in subpopulations of cells previously suggested to be stem-like/tumor-initiating cancer cells. ACD-NRCC was independent of cell-to-cell contact, and was regulated by the cancer niche in a heat-sensitive paracrine fashion. Wnt pathway genes and proteins are differentially expressed in cells undergoing ACD-NRCC vs. symmetric cell division. Blocking the Wnt pathway with IWP2 (WNT antagonist) or siRNA-TCF4 resulted in suppression of ACD-NRCC. However, using a Wnt-agonist did not increase the relative proportion of cells undergoing ACD-NRCC. CONCLUSION: Gastrointestinal cancers contain subpopulations of cells capable of ACD-NRCC. Here we show for the first time that ACD-NRCC can be regulated by the Wnt pathway, and by the cancer niche in a paracrine fashion. However, whether ACD-NRCC is exclusively associated with stem-like cancer cells remains to be determined. Further study of these findings might generate novel insights into stem cell and cancer biology. Targeting the mechanism of ACD-NRCC might engender novel approaches for cancer therapy.

Label-retaining liver cancer cells are relatively resistant to sorafenib.

OBJECTIVE: The standard therapy for advanced hepatocellular carcinoma (HCC) is sorafenib, with most patients experiencing disease progression within 6 months. Label-retaining cancer cells (LRCC) represent a novel subpopulation of cancer stem cells (CSC). The objective was to test whether LRCC are resistant to sorafenib. METHODS: We tested human HCC derived LRCC and non-LRCC before and after treatment with sorafenib. RESULTS: LRCC derived from human HCC are relatively resistant to sorafenib. The proportion of LRCC in HCC cell lines is increased after sorafenib while the general population of cancer cells undergoes growth suppression. We show that LRCC demonstrate improved viability and toxicity profiles, and reduced apoptosis, over non-LRCC. We show that after treatment with sorafenib, LRCC upregulate the CSC marker aldehyde dehydrogenase 1 family, wingless-type MMTV-integration-site family, cell survival and proliferation genes, and downregulate apoptosis, cell cycle arrest, cell adhesion and stem cells differentiation genes. This phenomenon was accompanied by non-uniform activation of specific isoforms of the sorafenib target proteins extracellular-signal-regulated kinases and v-akt-murine-thymoma-viral-oncogene homologue (AKT) in LRCC but not in non-LRCC. A molecular pathway map for sorafenib treated LRCC is proposed. CONCLUSIONS: Our results suggest that HCC derived LRCC are relatively resistant to sorafenib. Since LRCC can generate tumours with as few as 10 cells, our data suggest a potential role for these cells in disease recurrence. Further investigation of this phenomenon might provide novel insights into cancer biology, cancer recurrence and drug resistance with important implications for the development of novel cancer therapies based on targeting LRCC.

Tumor-initiating label-retaining cancer cells in human gastrointestinal cancers undergo asymmetric cell division.

Label-retaining cells (LRCs) have been proposed to represent adult tissue stem cells. LRCs are hypothesized to result from either slow cycling or asymmetric cell division (ACD). However, the stem cell nature and whether LRC undergo ACD remain controversial. Here, we demonstrate label-retaining cancer cells (LRCCs) in several gastrointestinal (GI) cancers including fresh surgical specimens. Using a novel method for isolation of live LRCC, we demonstrate that a subpopulation of LRCC is actively dividing and exhibits stem cells and pluripotency gene expression profiles. Using real-time confocal microscopic cinematography, we show live LRCC undergoing asymmetric nonrandom chromosomal cosegregation LRC division. Importantly, LRCCs have greater tumor-initiating capacity than non-LRCCs. Based on our data and that cancers develop in tissues that harbor normal-LRC, we propose that LRCC might represent a novel population of GI stem-like cancer cells. LRCC may provide novel mechanistic insights into the biology of cancer and regenerative medicine and present novel targets for cancer treatment.