Differential epigenetic regulation of Aiolos expression in human tumoral cell lines and primary cells

Targeting Ikaros and Aiolos with pomalidomide fails to reactivate or induce apoptosis of the latent HIV reservoir

HIV persists in people living with HIV (PLHIV) on antiretroviral therapy (ART) in long-lived and proliferating latently infected CD4+ T cells that selectively express pro-survival proteins, including the zinc finger proteins, Ikaros and Aiolos. In this study, we investigated whether pomalidomide, an immunomodulatory agent that induces degradation of Ikaros and Aiolos, could increase the death of HIV-infected cells and/or reverse HIV latency. Using an in vitro model of CD4+ T cells infected with a green fluorescent protein (GFP) reporter virus, pomalidomide increased the expression of the pro-survival protein B cell lymphoma (Bcl)-2 and did not increase apoptosis of GFP+ HIV productively infected CD4+ T cells. Pomalidomide also increased the expression of CD155 and UL16-binding protein (ULBP) stress proteins on GFP+ HIV productively infected CD4+ T cells, but this did not translate to enhanced clearance following co-culture with a natural killer (NK) cell line. Using CD4+ T cells from PLHIV on ART, pomalidomide ex vivo activated memory CD4+ T cells resulting in elevated HLA-DR expression and induced CD4+ T cell proliferation but only in the presence of T cell receptor stimulation with anti-CD3 and anti-CD28. There was no effect on cell-associated HIV RNA or the frequency of intact HIV DNA. In conclusion, despite an increase in stress protein expression, promoting Ikaros and Aiolos degradation in CD4+ T cells using pomalidomide did not directly induce apoptosis of HIV-infected cells or induce HIV latency reversal.IMPORTANCEPeople living with HIV (PLHIV) require lifelong antiretroviral therapy (ART) due to the persistence of latently infected cells. The zinc finger proteins, Ikaros and Aiolos, have recently been implicated in promoting the persistence of latently infected cells. In this study, we investigated the effects of pomalidomide, an immunomodulatory imide drug that induces the degradation of Ikaros and Aiolos, on HIV latency reversal and death of infected cells. Using CD4+ T cells from people living with HIV on suppressive antiretroviral therapy, as well as an in vitro model of productive HIV infection, we found that pomalidomide induced T cell activation and expression of stress proteins but no evidence of latency reversal or selective death of infected cells.

Variations in HPV function are associated with survival in squamous cell carcinoma

Incidence of HPV+ oropharyngeal squamous cell carcinoma (OPSCC) has been increasing dramatically. Although long-term survival rates for these patients are high, they often suffer from permanent radiotherapy-related morbidity. This has prompted the development of de-escalation clinical protocols to reduce morbidity. However, a subset of patients do not respond even to standard therapy and have poor outcomes. It is unclear how to properly identify and treat the high- and low-risk HPV+ OPSCC patients. Since HPV positivity drives radiotherapy sensitivity, we hypothesized that variations in HPV biology may cause differences in treatment response and outcome. By analyzing gene expression data, we identified variations in HPV-related molecules among HPV+ OPSCC. A subset of tumors presented a molecular profile distinct from that of typical HPV+ tumors and exhibited poor treatment response, indicating molecular and clinical similarities with HPV- tumors. These molecular changes were also observed in vitro and correlated with radiation sensitivity. Finally, we developed a prognostic biomarker signature for identification of this subgroup of HPV+ OPSCC and validated it in independent cohorts of oropharyngeal and cervical carcinomas. These findings could translate to improved patient stratification for treatment deintensification and new therapeutic approaches for treatment-resistant HPV-related cancer.

Deregulation of Aiolos expression in chronic lymphocytic leukemia is associated with epigenetic modifications

Chronic lymphocytic leukemia (CLL) is characterized by a clonal accumulation of mature neoplastic B cells that are resistant to apoptosis. Aiolos, a member of the Ikaros family of zinc-finger transcription factors, plays an important role in the control of mature B lymphocyte differentiation and maturation. In this study, we showed that Aiolos expression is up-regulated in B-CLL cells. This overexpression does not implicate isoform imbalance or disturb Aiolos subcellular localization. The chromatin status at the Aiolos promoter in CLL is defined by the demethylation of DNA and an enrichment of euchromatin associated histone markers, such as the dimethylation of the lysine 4 on histone H3. These epigenetic modifications should allow its upstream effectors, such as nuclear factor-κB, constitutively activated in CLL, to gain access to promoter, resulting up-regulation of Aiolos. To determine the consequences of Aiolos deregulation in CLL, we analyzed the effects of Aiolos overexpression or down-regulation on apoptosis. Aiolos is involved in cell survival by regulating the expression of some Bcl-2 family members. Our results strongly suggest that Aiolos deregulation by epigenetic modifications may be a hallmark of CLL.

Differential aiolos expression in human hematopoietic subpopulations

The Aiolos transcription factor plays a crucial role in the control of lymphocyte differentiation and proliferation. The expression of Aiolos isoform has been studied in lymphoid pathologies but nothing is known about its expression in unaffected human hematopoietic subpopulations. In this manuscript we show for the first time the differential Aiolos expression at the RNA and protein level in hematopoietic cell subpopulations. B cells express higher levels of Aiolos than NK and T cells while monocytes express almost undetectable levels of Aiolos. Moreover, human CD34 (+) progenitors do not express Aiolos. We did not observe significant difference when comparing naive to memory T and B cells, but we observed an important difference between Bright and Dim NK cells. Furthermore, we show that, in addition to hematopoietic cells, non hematopoietic cell lines such as MCF-7, SW480, HEK, PC3 and HeLa also express Aiolos.

The Aiolos transcription factor is up-regulated in chronic lymphocytic leukemia

The Aiolos transcription factor, member of the Ikaros family of zinc finger proteins, plays an important role in the control of mature B lymphocyte differentiation and proliferation, and its function appears to be modulated through alternative splicing. To assess Aiolos isoform role in humans' pathologies, we studied Aiolos variant distribution and expression in mature B lymphoproliferative disorders (chronic lymphocytic leukemia [CLL] and other B-cell lymphomas). We demonstrated that more than 80% of expressed Aiolos in normal as well as in malignant B cells is of the hAio1 type, and we showed for the first time a homogeneous overexpression of the total amounts of Aiolos transcripts in the B cells of CLL patients, independently of ZAP-70 and IgVH mutational status prognosis factors. This up-regulation of Aiolos, confirmed at protein level, seems independent of Aiolos promoter H3K9 acetylation and H3K4 trimethylation.