Protein kinase C inhibitors override ZEB1-induced chemoresistance in HCC

Epithelial-mesenchymal transition (EMT) is a process by which tumour cells lose epithelial characteristics, become mesenchymal and highly motile. EMT pathways also induce stem cell features and resistance to apoptosis. Identifying and targeting this pool of tumour cells is a major challenge. Protein kinase C (PKC) inhibition has been shown to eliminate breast cancer stem cells but has never been assessed in hepatocellular cancer (HCC). We investigated ZEB family of EMT inducer expression as a biomarker for metastatic HCC and evaluated the efficacy of PKC inhibitors for HCC treatment. We showed that ZEB1 positivity predicted patient survival in multiple cohorts and also validated as an independent biomarker of HCC metastasis. ZEB1-expressing HCC cell lines became resistant to conventional chemotherapeutic agents and were enriched in CD44high/CD24low cell population. ZEB1- or TGFβ-induced EMT increased PKCα abundance. Probing public databases ascertained a positive association of ZEB1 and PKCα expression in human HCC tumours. Inhibition of PKCα activity by small molecule inhibitors or by PKCA knockdown reduced viability of mesenchymal HCC cells in vitro and in vivo. Our results suggest that ZEB1 expression predicts survival and metastatic potential of HCC. Chemoresistant/mesenchymal HCC cells become addicted to PKC pathway and display sensitivity to PKC inhibitors such as UCN-01. Stratifying patients according to ZEB1 and combining UCN-01 with conventional chemotherapy may be an advantageous chemotherapeutic strategy.

Targeting Carcinoembryonic Antigen with DNA Vaccination: On-Target Adverse Events Link with Immunologic and Clinical Outcomes

PURPOSE

We have clinically evaluated a DNA fusion vaccine to target the HLA-A*0201-binding peptide CAP-1 from carcinoembryonic antigen (CEA605-613) linked to an immunostimulatory domain (DOM) from fragment C of tetanus toxin.

EXPERIMENTAL DESIGN

Twenty-seven patients with CEA-expressing carcinomas were recruited: 15 patients with measurable disease (arm-I) and 12 patients without radiological evidence of disease (arm-II). Six intramuscular vaccinations of naked DNA (1 mg/dose) were administered up to week 12. Clinical and immunologic follow-up was up to week 64 or clinical/radiological disease.

RESULTS

DOM-specific immune responses demonstrated successful vaccine delivery. All patients without measurable disease compared with 60% with advanced disease responded immunologically, while 58% and 20% expanded anti-CAP-1 CD8+ T cells, respectively. CAP-1-specific T cells were only detectable in the blood postvaccination but could also be identified in previously resected cancer tissue. The gastrointestinal adverse event diarrhea was reported by 48% of patients and linked to more frequent decreases in CEA (P < 0.001) and improved global immunologic responses [anti-DOM responses of greater magnitude (P < 0.001), frequency (P = 0.004), and duration] compared with patients without diarrhea. In advanced disease patients, decreases in CEA were associated with better overall survival (HR = 0.14, P = 0.017). CAP-1 peptide was detectable on MHC class I of normal bowel mucosa and primary colorectal cancer tissue by mass spectrometry, offering a mechanistic explanation for diarrhea through CD8+ T-cell attack.

CONCLUSIONS

Our data suggest that DNA vaccination is able to overcome peripheral tolerance in normal and tumor tissue and warrants testing in combination studies, for example, by vaccinating in parallel to treatment with an anti-PD1 antibody. Clin Cancer Res; 22(19); 4827-36. ©2016 AACR.

Human islet isolation--a prospective randomized comparison of pancreatic vascular perfusion with hyperosmolar citrate or University of Wisconsin solution

University of Wisconsin solution has become the most commonly used vascular perfusate during multiorgan donation world-wide. In the UK however, hyperosmolar citrate remains in common use. The purpose of this prospective randomized study was to compare the effect of systemic perfusion with UW or HOC on subsequent islet yield and purification for pancreata with short cold ischemic times. Seven pancreata were randomized to each group, with the donor age, pancreas weight, and period of cold ischemia being similar in both. Perfusion with UW was shown to inhibit collagenase digestion, and a higher concentration of this enzyme was needed to achieve comparable numbers of islets with good separation of exocrine and islet tissue after a similar period of digestion. There were no differences in the number, size, purity, or viability of islets between the two groups. In conclusion, UW solution offers no benefits over HOC for pancreata with short cold ischemic times, and because of its expense and need to use greater amounts of collagenase enzyme, we continue to use HOC.

Gamma irradiation of isolated rat islets pretransplantation produces indefinite allograft survival in cyclosporine-treated recipients

In this study we have examined the use of low-dose gamma-irradiation for the reduction of islet immunogenicity in the strong allogeneic combination of WAG rat islets transplanted into diabetic AUG recipients. First, we determined that gamma-irradiation reduced immunogenicity in vitro by use of a modified MLR with WAG islets as stimulators and AUG splenocytes as responders. We then determined the maximum dose of gamma-irradiation that could be used (250 rads) before islet function was affected. As 250 rads islet pretreatment alone was ineffective in prolonging allograft survival, we combined the pretreatment with a short course (days 0, 1, 2; 30 mg/kg) of cyclosporine. We found that CsA was only effective in significantly prolonging allograft survival when given subcutaneously in olive oil. The CsA treatment alone gave a significantly prolonged survival time for the islet allografts (median, 37 days vs. 6 days for controls), but when combined with the 250 rads islet pretreatment a synergistic effect was seen with 100% becoming long-term survivors (greater than 100 days). The long-term surviving AUG rats from both the CsA alone group and the CsA plus 250 rads pretreated islets group were challenged with WAG dendritic cells (DC). The islets from the 250 rads pretreated group were subsequently rejected (day 6) while the CsA alone group were not affected. The role of low dose gamma-irradiation when combined with CsA treatment of islet graft recipients in inducing specific unresponsiveness will be discussed.