Neurochemical Research

, Volume 34, Issue 1, pp 66–78 | Cite as

Bcl-2 siRNA Augments Taxol Mediated Apoptotic Death in Human Glioblastoma U138MG and U251MG Cells

  • Joseph George
  • Naren L. Banik
  • Swapan K. Ray
Original Paper


The anti-neoplastic drug taxol binds to β-tubulin to prevent tumor cell division, promoting cell death. However, high dose taxol treatment may induce cell death in normal cells too. The anti-apoptotic molecule Bcl-2 is upregulated in many cancer cells to protect them from apoptosis. In the current study, we knocked down Bcl-2 expression using cognate siRNA during low-dose taxol treatment to induce apoptosis in two human glioblastoma U138MG and U251MG cell lines. The cells were treated with either 100 nM taxol or 100 nM Bcl-2 siRNA or both for 72 h. Immunofluorescent stainings for calpain and active caspase-3 showed increases in expression and co-localization of these proteases in apoptotic cells. Fluorometric assays demonstrated increases in intracellular free [Ca2+], calpain, and caspase-3 indicating augmentation of apoptosis. Western blotting demonstrated dramatic increases in the levels of Bax, Bak, tBid, active caspases, DNA fragmentation factor-40 (DFF40), cleaved fragments of lamin, fodrin, and poly(ADP-ribose) polymerase (PARP) during apoptosis. The events related to apoptosis were prominent more in combination therapy than in either treatment alone. Our current study demonstrated that Bcl-2 siRNA significantly augmented taxol mediated apoptosis in different human glioblastoma cells through induction of calpain and caspase proteolytic activities. Thus, combination of taxol and Bcl-2 siRNA offers a novel therapeutic strategy for controlling the malignant growth of human glioblastoma cells.


Apoptosis Bcl-2 siRNA Calpain Glioblastoma Taxol 



This investigation was supported in part by the R01 grants (CA-91460 and NS-57811) from the National Institutes of Health (Bethesda, MD) to S.K.R.


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Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • Joseph George
    • 1
  • Naren L. Banik
    • 1
  • Swapan K. Ray
    • 2
    • 3
  1. 1.Department of NeurosciencesMedical University of South CarolinaCharlestonUSA
  2. 2.Department of Pathology, Microbiology and ImmunologyUniversity of South Carolina School of MedicineColumbiaUSA
  3. 3.Department of Microbiology and ImmunologyMedical University of South CarolinaCharlestonUSA

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