Antitumor activity of sorafenib plus CDK4/6 inhibitor in pancreatic patient derived cell with KRAS mutation

Medulloblastoma malignant biological behaviors are associated with HOTAIR/miR-483-3p/CDK4 axis

BACKGROUND

Medulloblastoma is the most common malignant brain tumor in children. Although the 5-year survival rate is high, patients with relapsed medulloblastoma have a guarded prognosis. HOX transcript antisense RNA (HOTAIR) has been proved to be related to the metastasis of various tumors. Therefore, the molecular mechanism of HOTAIR in medulloblastoma cells was investigated in this study.

METHODS

HOTAIR was stably silenced in medulloblastoma cells (Daoy and D341). Cell proliferation and apoptosis were detected by 5'-Bromo-2'-deoxyuridine (BrdU) staining, Hoechst 33342 staining, immunohistochemical (IHC), Terminal-deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) and flow cytometry, respectively. The targeted relationship between HOTAIR/Cyclin-dependent kinase 4 (CDK4) and miR-483-3p were predicted by bioinformatics and confirmed by luciferase reporter assay. Balb/C nude mice were inoculated with shRNA-HOTAIR transfected Daoy cells.

RESULTS

We found that the down-regulation of HOTAIR inhibited proliferation and induced apoptosis. Sh-RNA-HOTAIR also inhibited the expression of CKD4. The CDK4 dependent increase of cell proliferation and decrease of cell apoptosis were reversed by shRNA-HOTAIR. Finally, a xenograft model of medulloblastoma in nude mice was built, and the effect of shRNA-HOTAIR on the growth of tumors was analyzed by RT-PCR, immunofluorescence staining, and TUNEL staining. The data suggested interference of HOTAIR inhibited the growth, tumor weight, cell proliferation, and promoted cell apoptosis.

CONCLUSIONS

Our study altogether demonstrated HOTAIR influence cell proliferation and apoptosis by regulation of miR-483-3p and CDK4 in medulloblastoma cells. HOTAIR can be used as a candidate for potential applications in the treatment of medulloblastoma.

SPH3643: A novel cyclin-dependent kinase 4/6 inhibitor with good anticancer efficacy and strong blood-brain barrier permeability

The cyclin‐dependent kinase (CDK)4/6‐cyclin D1‐Rb‐p16/ink4a pathway is responsible for regulating cell progression past the G₁ restriction point during the cell cycle. The development of a majority of human tumors is associated with dysregulation of this pathway, resulting in increased cancer cell proliferation. Both CDK4 and CDK6, well‐validated cancer drug targets, function primarily as catalytic enzymes that mediate the phosphorylation of retinoblastoma protein (Rb). Here, we determined that SPH3643 is a novel potent antiproliferative agent that inhibits CDK4/6 kinase activity. In biochemical assays, SPH3643 showed more potent inhibition of both CDK4 and CDK6 than did 2 published CDK4/6 inhibitors, LY2835219 and palbociclib, and had better selectivity than LY2835219. Further in vitro study revealed that SPH3643 blocked Cdk/Rb signaling by inhibiting the phosphorylation of Rb^Ser780 and arrested the MCF‐7 cancer cells at G₀/G₁ phase, resulting in marked inhibition of the proliferation of Rb‐positive cancer cell lines. In vivo SPH3643 treatment in mice bearing xenograft tumor models of breast cancer, colon cancer, acute myelocytic leukemia, and glioblastoma resulted in significant decreases in tumor growth. SPH3643 was able to particularly strongly inhibit glioblastoma (U87‐MG) cell growth in the brains of orthotopic carcinoma xenograft mice due to its high degree of intracerebral penetration and significant persistence in this setting. Together these results revealed that SPH3643 is a potent, orally active small‐molecule inhibitor of CDK4/6 with robust anticancer efficacy and a high degree of blood‐brain barrier permeability.

Update on current pancreatic treatments: from molecular pathways to treatment

Pancreatic cancer is still diagnosed at a late stage although we have novel diagnostic tools. Pancreatic cancer chemotherapy treatment resistance is observed and therefore novel treatments are in need. Anti-cancer stem cell therapy, combination of chemotherapy and/or radiotherapy with immunotherapy, proteins/enzymes and gene therapy are currently under evaluation. Targeted treatment with tyrosine kinase inhibitors is also administered and novel inhibitors are also under evaluation. In the current review we present recent data from our search within the year 2018.