Bax and Bid act in synergy to bring about T11TS-mediated glioma apoptosis via the release of mitochondrial cytochrome c and subsequent caspase activation

Abstract

The specific apoptotic role of T11TS has been well established in glioma animal models. T11TS specifically induces the glioma cells to die an apoptotic death via immune cross-talk with the two intracranial immune competent cells-microglia and the brain-infiltrating lymphocytes. To unearth the molecular cascades operative within the glioma cells and to some extent in the two interacting immunocytes, we had initiated studies where preliminary findings not only had indicated the involvement of death receptors but had also hinted to the involvement of other apoptotic regulators. Hence, to identify the molecular pathway of apoptosis involving other apoptotic regulators in the three cell types, the cells were studied for the intrinsic apoptotic death regulators that were engaged to maintain the mitochondrial membrane integrity. The proteins that were selected could be divided into three broad classes-the Bcl-2 family of proteins-Bid, Bax and Bcl-2; the guardian of the genome p53 and the proteins downstream of mitochondria-Apaf-1, cytochrome c, caspase-9 and caspase-3. Activated Bid as well as maximal p53 expression was observed in the first dose of T11TS thus dually activating the pro-apoptotic Bax in the first and second dose in the glioma cells. Concurrently, the pro-survival protein Bcl-2's expression level was very much down-regulated in the same two doses favoring the internal microenvironment to proceed for apoptosis. High expression of cytochrome c and Apaf-1 and the presence of active caspase-9 and active caspase-3 in all the T11TS-treated tumor-bearing groups further adjudicated apoptosis of the glioma cells with clear involvement of mitochondrial death pathway in the T11TS-treated animals. Even though expression of the apoptotic regulators remained more or less the same indicating the involvement of mitochondria in the two interacting immunocytes, the intensity of expression of these proteins was much lower than the tumor cells. The present work focuses on the mechanistic approach of how T11TS mediates apoptosis and hence is the first approach of its kind in the field of immunology where the immunotherapeutic molecule's mode of action has been worked out.

The novel immunotherapeutic molecule T11TS modulates glioma-induced changes of key components of the immunological synapse in favor of T cell activation and glioma abrogation

“…CD2 also has roles in T-cell survival by preventing Fas/FasL-mediated apoptosis [59], which indicates glioma-mediated T-cell apoptosis may partly be due to CD2 downregulation in glioma. Also inhibition of Fas/FasL-mediated apoptosis upon T11TS application has been demonstrated in earlier work by our group [58], which indicates that T11TS-mediated CD2 upregulation may be a direct cause in inhibition of T-cell apoptosis.…”

“…Further, a steep rise in T-cell cytotoxicity has also been observed upon administration of three doses of T11TS in the in vivo rat glioma model [60]. It is thus evident that although other facets of glioma killing upon T11TS administration are evident (by cytokine modulation, immune potentiation, inhibition of glioma cell cycle, specific apoptotic induction and anti-angiogenic therapy) [16,47,58,61], such T11TS-induced glioma abrogation due to T-cell activation is also a major mode of killing.…”

“…f-chain downregulation in glioma-associated T-cells could be apoptosis-mediated since its cytoplasmic domain is prone to caspase-mediated proteolysis [57]. Upregulated caspase activity in glioma-associated lymphocytes and its downregulation upon T11TS treatment has been established [58], explaining CD3f expression patterns in glioma and on T11TS treatment. CD2 also has roles in T-cell survival by preventing Fas/FasL-mediated apoptosis [59], which indicates glioma-mediated T-cell apoptosis may partly be due to CD2 downregulation in glioma.…”

Glia to glioma: A wrathful journey

“…T11 target structure (T11TS), one of the most promising immuno-therapeutic glycoprotein isolated from the membrane of sheep erythrocyte, has been found to either induce Bax-Bid-mitochondrial cytochrome c-mediated caspase-related glioma cell destruction or inhibit veGF-mediated angiogenesis by decreasing the expression of PI3K-Akt, which comes handy in glioma treatment, though it is still awaiting clinical trial [147][148][149] .…”

Therapeutic Profile of T11TS vs. T11TS+MiADMSA: A Hunt for a More Effective Therapeutic Regimen for Arsenic Exposure

“…It has been established in our earlier work that T11TS / SLFA-3 is a potent immune potentiator and has anti neoplastic activity (Sarkar et al, 2004). It also acts as a cytokine modulator (Ghosh et al, 2010), a cell cycle modulator , a specific apoptotic inducer (Bhattacharjee et al, 2008), and an anti-angiogenic agent. The present study is novel because it aims to combine the effects of immune potentiation with T11TS with chelation therapy in the eradication of arsenic induced carcinogenesis.…”