Paclitaxel sensitivity of breast cancer cells with constitutively active NF-kappaB is enhanced by IkappaBalpha super-repressor and parthenolide

The transcription factor nuclear factor-kappaB (NF-kappaB) regulates genes important for tumor invasion, metastasis and chemoresistance. Normally, NF-kappaB remains sequestered in an inactive state by cytoplasmic inhibitor-of-kappaB (IkappaB) proteins. NF-kappaB translocates to nucleus and activates gene expression upon exposure of cells to growth factors and cytokines. We and others have shown previously that NF-kappaB is constitutively active in a subset of breast cancers. In this study, we show that constitutive activation of NF-kappaB leads to overexpression of the anti-apoptotic genes c-inhibitor of apoptosis 2 (c-IAP2) and manganese superoxide dismutase (Mn-SOD) in breast cancer cells. Furthermore, expression of the anti-apoptotic tumor necrosis factor receptor associated factor 1 (TRAF1) and defender-against cell death (DAD-1) is regulated by NF-kappaB in certain breast cancer cells. We also demonstrate that NF-kappaB-inducible genes protect cancer cells against paclitaxel as MDA-MB-231 breast cancer cells modified to overexpress IkappaBalpha required lower concentrations of paclitaxel to arrest at the G2/M phase of the cell cycle and undergo apoptosis when compared to parental cells. The effect of NF-kappaB on paclitaxel-sensitivity appears to be specific to cancer cells because normal fibroblasts derived from embryos lacking p65 subunit of NF-kappaB and wild type littermate embryos were insensitive to paclitaxel-induced G2/M cell cycle arrest. Parthenolide, an active ingredient of herbal remedies such as feverfew (tanacetum parthenium), mimicked the effects of IkappaBalpha by inhibiting NF-kappaB DNA binding activity and Mn-SOD expression, and increasing paclitaxel-induced apoptosis of breast cancer cells. These results suggest that active ingredients of herbs with anti-inflammatory properties may be useful in increasing the sensitivity of cancers with constitutively active NF-kappaB to chemotherapeutic drugs. Oncogene (2000) 19, 4159 - 4169

IL-15 promotes survival but not effector function differentiation of CD8+ TCRalphabeta+ intestinal intraepithelial lymphocytes

CD8 single-positive cells, including CD8alphaalpha+ and CD8alphabeta+ subsets, constitute the majority of TCRalphabeta+ intestinal intraepithelial lymphocytes (alphabeta iIEL) in mice. CD8+ alphabeta iIEL show significantly weaker responses to TCR stimulation in the presence of exogenous IL-2 than do CD8+ T cells of the central immune system. IL-15 is a T cell growth factor likely expressed in the intestine mucosa. To understand the role of IL-15 in CD8+ alphabeta iIEL biology, we compared the effects of exogenous IL-15 and IL-2 on the survival and primary responses of the two CD8+ alphabeta iIEL subsets in vitro. In contrast to the death of approximately 60% of both CD8alphaalpha+ and CD8alphabeta+ iIEL cultured in IL-2 with or without TCR stimulation, IL-15 promoted survival of the CD8alphaalpha+ subset in the presence of TCR stimulation and promoted survival of both subsets in the absence of TCR stimulation. The higher proliferation level of TCR stimulated CD8alphaalpha+ alphabeta iIEL cultured in IL-15 compared with those cultured in IL-2 is likely due to IL-15's prosurvival effects. In addition, unlike exogenous IL-2, exogenous IL-15 did not support the effector functions of either iIEL subsets, including IFN-gamma production, IL-4-induced Th2 cytokine production, and anti-TCR mAb-redirected cytotoxicity. These findings demonstrate that IL-15 and IL-2 are functionally distinct and suggest that IL-15 plays a unique role in the maintenance of the CD8+ alphabeta iIEL pool in the absence of Ag stimulation and in the survival and expansion of CD8alphaalpha+ alphabeta iIEL upon Ag stimulation.

Modulation of cytokine responses of murine CD8+ alphabeta intestinal intraepithelial lymphocytes by IL-4 and IL-12

The immune responses of the intestine mucosa feature the noninflammatory type, such as IgA production and oral tolerance. Th2 type cytokines have been implicated in the induction of these noninflammatory responses. In the present study, cytokine responses of CD8+ and CD4+ TCRalphabeta+ intestinal intraepithelial lymphocyte (alphabeta iIEL) subsets to TCR stimulation under the influence of IL-12, IL-4, or CD28 costimulation were examined. IL-12 enhanced production of IL-10 and IFN-gamma by the CD8alphabeta+ alphabeta iIEL significantly but only marginally affected the CD8alphaalpha+ subset, whereas IL-4 induced IL-4, IL-5, and IL-10 production and augmented TGF-beta production by both subsets. CD28 costimulation induced production of Th2 cytokines by CD4+ iIEL in the absence of exogenous IL-4. Unlike lymph node CD4+ cells, the CD28 costimulation-induced Th2 differentiation of CD4+ iIEL was not inhibited by IFN-gamma. These results demonstrate active cytokine production by CD4+, CD8alphabeta+, as well as CD8alphaalpha+ alphabeta iIEL. The Th2- skewed cytokine profile of CD8alphaalpha+ alphabeta iIEL and the IFN-gamma-resistance of Th2 differentiation of the CD4+ alphabeta iIEL suggest that both iIEL subsets contribute to the induction of noninflammatory mucosal immune responses.

Distinct actions of interleukin-9 and interleukin-4 on a hematopoietic stem cell line, EMLC1

EMLC1 is a hematopoietic stem cell line that depends on stem cell factor (SCF) for growth and generates lymphoid, erythroid and myeloid progenitors in the presence of different cytokines. We have studied signaling events leading to cell proliferation and differentiation of EMLC1 mediated by interleukin (IL)-4 and IL-9. It was found that IL-9 enhances SCF-induced cell proliferation and promotes erythropoietin (EPO)-dependent erythroid differentiation of EMLC1 cells. However, IL-9 alone cannot support the growth of this cell line. In contrast, IL-4 by itself is sufficient to promote the growth of EMLC1 cells, even in the absence of SCF. Antiphosphotyrosine immunoblots of total cell lysates demonstrated that IL-4 and IL-9 induce tyrosine phosphorylation of different cellular substrates. Both IL-4 and IL-9 stimulated tyrosine phosphorylation of SHP-2, whereas the 90-kD tyrosine phosphorylated protein induced by IL-9 stimulation is Stat3. We have also shown that IL-4 is much more potent than IL-9 in inducing the expression of primary response gene c-myc. It was further determined that c-myc antisense oligodeoxynucleotide blocked IL-4 supported cell growth. Taken together, these results indicate that IL-4 may serve as a growth-promoting factor for hematopoietic stem cells, and IL-9 enhances both growth and erythroid differentiation of primitive hematopoietic progenitors. The results also suggest that differences in tyrosine phosphorylation induced by IL-4 and IL-9 may in part determine their distinct biological functions.

Activated alpha beta-CD8+, but not alpha alpha-CD8+, TCR-alpha beta+ murine intestinal intraepithelial lymphocytes can mediate perforin-based cytotoxicity, whereas both subsets are active in Fas-based cytotoxicity

CD8 single-positive (CD8+) T cells in murine intestinal intraepithelial lymphocytes (iIEL) consist of alpha alpha-CD8+ and alpha beta-CD8+ subpopulations. Cytotoxicity represents an important function of peripheral CD8+ T cells, so we examined perforin-granzymebased and Fas-based cytotoxicity of activated CD8+ TCR-alpha beta+ iIEL subsets. We found that allospecific CTL activity was induced from alpha beta-CD8+ iIEL but not from alpha alpha-CD8+ iIEL even when allospecific TCR were present on the iIEL, as demonstrated by using 2C TCR transgenic mice. On the other hand, both CD8+ iIEL subsets proliferated upon allostimulation with a lower responder frequency than CD8+ LN cells. The alpha alpha-CD8+ TCR-alpha beta+ iIEL appeared to lose their ability to perform perforin-based killing after activation through TCR because fresh cells lysed P815 cells coated with anti-TCR beta-chain (TCR-beta) mAb, whereas cells activated by plate-bound anti-TCR mAb did not. Of interest, both activated CD8+ TCR-alpha beta+ iIEL subsets, but not fresh cells, were able to mediate Fas-based killing when triggered with PMA and CA2+ ionophore.

Activated alpha beta-CD8+, but not alpha alpha-CD8+, TCR-alpha beta+ murine intestinal intraepithelial lymphocytes can mediate perforin-based cytotoxicity, whereas both subsets are active in Fas-based cytotoxicity

CD8 single-positive (CD8+) T cells in murine intestinal intraepithelial lymphocytes (iIEL) consist of alpha alpha-CD8+ and alpha beta-CD8+ subpopulations. Cytotoxicity represents an important function of peripheral CD8+ T cells, so we examined perforin-granzymebased and Fas-based cytotoxicity of activated CD8+ TCR-alpha beta+ iIEL subsets. We found that allospecific CTL activity was induced from alpha beta-CD8+ iIEL but not from alpha alpha-CD8+ iIEL even when allospecific TCR were present on the iIEL, as demonstrated by using 2C TCR transgenic mice. On the other hand, both CD8+ iIEL subsets proliferated upon allostimulation with a lower responder frequency than CD8+ LN cells. The alpha alpha-CD8+ TCR-alpha beta+ iIEL appeared to lose their ability to perform perforin-based killing after activation through TCR because fresh cells lysed P815 cells coated with anti-TCR beta-chain (TCR-beta) mAb, whereas cells activated by plate-bound anti-TCR mAb did not. Of interest, both activated CD8+ TCR-alpha beta+ iIEL subsets, but not fresh cells, were able to mediate Fas-based killing when triggered with PMA and CA2+ ionophore.

Differential requirement of CD28 costimulation for activation of murine CD8+ intestinal intraepithelial lymphocyte subsets and lymph node cells

The CD8+CD4- (CD8+) murine small intestinal intraepithelial lymphocytes (IELs) contain two subpopulations, one expressing alpha alpha-CD8 homodimers and another alpha beta-CD8 heterodimers. In this study, plate-bound anti-TCR beta-chain (TCR-beta) mAb alone or combined with anti-CD28 mAb is used as a model system to study activation requirement of these two CD8+ IEL subsets. In contrast to CD8+ lymph node (LN) cells that require both TCR and CD28 triggering for activation, alpha beta-CD8+ IELs proliferate and produce IL-2 and IFN-gamma when stimulated with anti-TCR-beta mAb alone, and soluble CTLA-4 Ig has no effect on their responses. On the other hand, alpha alpha-CD8+ IELs neither make IL-2 or IFN-gamma nor proliferate even when both stimuli are provided. However, alpha alpha-CD8+ IELs are capable of proliferation in both CD8+ IEL subsets is lower than in CD8+ LN cells, which contributes to the weaker and delayed response of CD8+ IELs.

Differential requirement of CD28 costimulation for activation of murine CD8+ intestinal intraepithelial lymphocyte subsets and lymph node cells

The CD8+CD4- (CD8+) murine small intestinal intraepithelial lymphocytes (IELs) contain two subpopulations, one expressing alpha alpha-CD8 homodimers and another alpha beta-CD8 heterodimers. In this study, plate-bound anti-TCR beta-chain (TCR-beta) mAb alone or combined with anti-CD28 mAb is used as a model system to study activation requirement of these two CD8+ IEL subsets. In contrast to CD8+ lymph node (LN) cells that require both TCR and CD28 triggering for activation, alpha beta-CD8+ IELs proliferate and produce IL-2 and IFN-gamma when stimulated with anti-TCR-beta mAb alone, and soluble CTLA-4 Ig has no effect on their responses. On the other hand, alpha alpha-CD8+ IELs neither make IL-2 or IFN-gamma nor proliferate even when both stimuli are provided. However, alpha alpha-CD8+ IELs are capable of proliferation in both CD8+ IEL subsets is lower than in CD8+ LN cells, which contributes to the weaker and delayed response of CD8+ IELs.