Correlation of an ex Vivo Model with Clinical Application of an Epigenetic Modifier, Inhibiting Tumor Growth and Metastasis, in Resistant Cholangiocarcinoma—A Case Study

Bile duct cancer is a rare form of cancer, with approximately 2000 new cases diagnosed in the United States each year. The prognosis of this disease is very grave, especially in the form of intrahepatic (IHCC), as there is no person with stage four who lives for 5 years, and the average prognosis is less than a year, a majority of patients die in less than 6 months despite all therapies. It is suggested that one of the key elements in the disease progression is the intratumoral hypoxia inducible factor one alfa (HIF-1a) as a regulator of malignant behavior and recently described as a new prognostic indicator of IHCC. (9, 10) HIF is a key regulator under the microenvironmental (terrain) influence, and therefore studies of the cell lines in an in vitro environment where there is no hypoxia, usually fail to translate to a clinical outcome in vivo, unless the cells are transfected by full-length HIF-1alpha (fL HIF-1alpha) and dominant-negative HIF-1alpha (dn HIF-1alpha). To overcome this barrier, an ex vivo model is designed at MD Anderson experimental therapeutics where the patient tumor sample is transferred to the mice and treated with drugs, where the tumor can cross talk with the actual terrain and mimic the human stroma where the HIF can be triggered. Results show significant tumor necrosis on the intrahepatic cholangiocacinoma, only after 5 days of exposure to an experimental compound that is known to suppress hypoxia-induced accumulation of hypoxia-inducible factor-1α (HIF-1α) through inhibiting protein synthesis. (11, 12) Further this is explored in the same actual patient with terminal diagnosis, and proves itself with promising initial response. Here, we review this method and the clinical perspectives, and suggest this method to be studied in larger trials.

In Vivo Therapeutic Silencing of Hypoxia-Inducible Factor 1 Alpha(HIF-1)Using Single-Walled Carbon Nanotubes Noncovalently Coated with siRNA

A new approach is described for delivering small interfering RNA(siRNA)into cancer cells by noncovalently complexing unmodifi ed siRNA with pristine single-walled carbon nanotubes(SWCNTs).The complexes were prepared by simple sonication of pristine SWCNTs in a solution of siRNA,which then served both as the cargo and as the suspending agent for the SWCNTs.When complexes containing siRNA targeted to hypoxia-inducible factor 1 alpha(HIF-1)were added to cells growing in serum containing culture media,there was strong specific inhibition of cellular HIF-1 activity.The ability to obtain a biological response to SWCNT/siRNA complexes was seen in a wide variety of cancer cell types.Moreover,intratumoral administration of SWCNT-HIF-1 siRNA complexes in mice bearing MiaPaCa-2/HRE tumors signifi cantly inhibited the activity of tumor HIF-1.As elevated levels of HIF-1 are found in many human cancers and are associated with resistance to therapy and decreased patient survival,these results imply that SWCNT/siRNA complexes may have value as therapeutic agents.

Expression of histone deacetylase (HDAC) family members in bortezomib-refractory multiple myeloma and modulation by panobinostat

Aim:Multiple myeloma(MM)is a hematological malignancy of antibody-producing mature B cells or plasma cells.The proteasome inhibitor,bortezomib,was the first-in-class compound to be FDA approved for MM and is frequently utilized in induction therapy.However,bortezomib refractory disease is a major clinical concern,and the efficacy of the pan-histone deacetylase inhibitor(HDACi),panobinostat,in bortezomib refractory disease indicates that HDAC targeting is a viable strategy.Here,we utilized isogenic bortezomib resistant models to profile HDAC expression and define baseline and HDACi-induced expression patterns of individual HDAC family members in sensitive vs.resistant cells to better understanding the potential for targeting these enzymes.Methods:Gene expression of HDAC family members in two sets of isogenic bortezomib sensitive or resistant myeloma cell lines was examined.These cell lines were subsequently treated with HDAC inhibitors:panobinostat or vorinostat,and HDAC expression was evaluated.CRISPR/Cas9 knockdown and pharmacological inhibition of specific HDAC family members were conducted.Results:Interestingly,HDAC6 and HDAC7 were significantly upregulated and downregulated,respectively,in bortezomib-resistant cells.Panobinostat was effective at inducing cell death in these lines and modulated HDAC expression in cell lines and patient samples.Knockdown of HDAC7 inhibited cell growth while pharmacologically inhibiting HDAC6 augmented cell death by panobinostat.Conclusion:Our data revealed heterogeneous expression of individual HDACs in bortezomib sensitive vs.resistant isogenic cell lines and patient samples treated with panobinostat.Cumulatively our findings highlight distinct roles for HDAC6 and HDAC7 in regulating cell death in the context of bortezomib resistance.