title: Induction of cell death in renal cell carcinoma with combination of D-fraction and vitamin C.
abstract: OBJECTIVE
  Although several conventional therapeutic options for advanced renal cell carcinoma (RCC) are currently available, the unsatisfactory outcomes demand establishing more effective interventions. D-fraction (PDF), a bioactive proteoglucan of Maitake mushroom, demonstrates anticancer and immunomodulatory activities, which are also shown to be potentiated by vitamin C (VC). We thus hypothesized that a combination of PDF and VC (PDF + VC) could be an alternative approach to more effectively inhibit the growth of RCC.
  
  
  METHODS
  We examined the dose-dependent effects of PDF + VC on RCC cell viability and also performed biochemical assays to explore the growth regulatory mechanism.
  
  
  METHODS
  Human RCC, ACHN cell line, was employed and exposed to varying concentrations of PDF or VC and their combinations. Cell viability at specified times was determined by MTT assay. Lipid peroxidation assay, cell cycle analysis, and Western blot analysis were also performed.
  
  
  RESULTS
  PDF or VC alone led to the significant reduction in cell viability at 72 hours with PDF >500 µg/mL and VC ≥300 µM. When various combinations of PDF and VC were tested, the combination of the ineffective concentrations of PDF (300 µg/mL) and VC (200 µM) resulted in ~90% cell death in 24 hours. Lipid peroxidation assay then indicated significantly (~2.5 fold) elevated oxidative stress with this PDF + VC. Cell cycle analysis also indicated a G1 cell cycle arrest following a 6-hour PDF + VC treatment. Western blots further revealed a downregulation of Bcl2, an upregulation of Bax, and proteolytic activation of PARP (poly[ADP-ribose] polymerase) in PDF + VC-treated cells, indicating induction of apoptosis.
  
  
  CONCLUSIONS
  The present study demonstrates that the combination of PDF and VC can become highly cytotoxic, inducing severe cell death in ACHN cells. This cytotoxic mechanism appears to be primarily attributed to oxidative stress, accompanied by a G1 cell cycle arrest. Such cell death induced by PDF + VC could be more likely linked to apoptosis, as indicated by the modulation of apoptosis regulators (Bcl2, Bax, and PARP). Therefore, as PDF and VC may work synergistically to induce apoptotic cell death, they may have clinical implications in an alternative, improved therapeutic modality for advanced RCC.
authors: New York Medical College, Valhalla, NY 10595, USA.
authors: Bobby
authors: B
authors: Alexander
authors: Andrew I
authors: AI
authors: Fishman
authors: Majid
authors: M
authors: Eshghi
authors: Muhammad
authors: M
authors: Choudhury
authors: Sensuke
authors: S
authors: Konno
mesh_terms: D001205:Ascorbic Acid / Q000494:pharmacology*; D002292:Carcinoma, Renal Cell / Q000473:pathology*; D016923:Cell Death / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004338:Drug Combinations; D004353:Drug Evaluation, Preclinical; D004357:Drug Synergism; D048691:Grifola / Q000737:chemistry*; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology*; D018384:Oxidative Stress / Q000187:drug effects; D010936:Plant Extracts / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D004338:Drug Combinations; D010936:Plant Extracts; D001205:Ascorbic Acid
keywords: D-fraction; apoptosis regulators; cell death; oxidative stress; renal cell carcinoma; vitamin C