Republication: Targeting PI3KC2β Impairs Proliferation and Survival in Acute Leukemia, Brain Tumours and Neuroendocrine Tumours

BACKGROUND Eight human catalytic phosphoinositide 3-kinase (PI3K) isoforms exist which are subdivided into three classes. While class I isoforms have been well-studied in cancer, little is known about the functions of class II PI3Ks. MATERIALS AND METHODS The expression pattern and functions of the class II PI3KC2β isoform were investigated in a panel of tumour samples and cell lines. RESULTS Overexpression of PI3KC2β was found in subsets of tumours and cell lines from acute myeloid leukemia (AML), glioblastoma multiforme (GBM), medulloblastoma (MB), neuroblastoma (NB), and small cell lung cancer (SCLC). Specific pharmacological inhibitors of PI3KC2β or RNA interference impaired proliferation of a panel of human cancer cell lines and primary cultures. Inhibition of PI3KC2β also induced apoptosis and sensitised the cancer cells to chemotherapeutic agents. CONCLUSION Together, these data show that PI3KC2β contributes to proliferation and survival in AML, brain tumours and neuroendocrine tumours, and may represent a novel target in these malignancies

Importance of Timing First-Trimester Placental Growth Factor and Use of Serial First-Trimester Placental Growth Factor Measurements in Screening for Preeclampsia.

OBJECTIVE The aims of this study were to test whether the performance of first-trimester placental growth factor (PlGF) in screening for preterm preeclampsia (PE) is gestational age dependent and to assess the value of serial first-trimester PlGF measurements in discriminating women at risk for PE. METHODS PlGF was measured in women with singleton pregnancies at their first antenatal visit at 8+0 to 10+6 and additionally at 11+0 to 14+0 weeks of gestation. The difference in absolute values of serial PlGF measurements was expressed as Δ-PlGF. Values were compared between pregnancies with normal outcome and those complicated by PE. RESULTS A total of 814 pregnancies were included, 18 (2.19%) developed PE that required delivery before 37 weeks of gestation. PlGF increases significantly from 8 to 14 weeks of gestation (ρ = 0.63; p < 0.0001) in normal pregnancies, but not so in preterm PE (ρ = 0.034; p = 0.893). PlGF discriminates between PE and uneventful pregnancies only after 10 weeks of gestation. Δ-PlGF was significantly lower in PE 5.3 (-1.1 to 9.3) pg/mL compared to uneventful pregnancies 17.3 (9.8-26.0) pg/mL (p = 0.0011). CONCLUSION The discriminatory accuracy of PlGF increases from 10 to 14 weeks of gestation, and serial PlGF measurements might be of particular interest in PE screening

Targeting PI3KC2β impairs proliferation and survival in acute leukemia, brain tumours and neuroendocrine tumours

BACKGROUND: Eight human catalytic phosphoinositide 3-kinase (PI3K) isoforms exist which are subdivided into three classes. While class I isoforms have been well-studied in cancer, little is known about the functions of class II PI3Ks. MATERIALS AND METHODS: The expression pattern and functions of the class II PI3KC2β isoform were investigated in a panel of tumour samples and cell lines. RESULTS: Overexpression of PI3KC2β was found in subsets of tumours and cell lines from acute myeloid leukemia (AML), glioblastoma multiforme (GBM), medulloblastoma (MB), neuroblastoma (NB), and small cell lung cancer (SCLC). Specific pharmacological inhibitors of PI3KC2β or RNA interference impaired proliferation of a panel of human cancer cell lines and primary cultures. Inhibition of PI3KC2β also induced apoptosis and sensitised the cancer cells to chemotherapeutic agents. CONCLUSION: Together, these data show that PI3KC2β contributes to proliferation and survival in AML, brain tumours and neuroendocrine tumours, and may represent a novel target in these malignancies

Inhibition of PI3K p110α impairs GBM cell proliferation and anchorage-independent growth.

<p>(A) Cell proliferation of GBM cells in the presence of class I_A PI3K isoform-specific inhibitors (72 h). (B) Cell proliferation of GBM cells transiently transfected with siRNA targeting class I_A PI3K isoforms p110α (PIK3CA), p110β (PIK3CB), or p110δ (PIK3CD) 48 h post transfection. TOX and SCR siRNAs were used as positive and negative, non-targeting controls, respectively. (C) Anchorage-independent growth (colony formation in soft agar) of GBM cells treated with PI3K p110α-specific inhibitors YM024, A66, PIK75, or PI3K p110β-specific inhibitor TGX221 (28 d). (D) Cell proliferation and anchorage-independent growth of GBM cells in the presence of the dual PI3K/mTOR inhibitor BEZ235 (72 h and 28 d, respectively). Curves and bars represent the means of three individual experiments ± standard deviation; single experiment for soft agar assay with BEZ235; *: p≤0.05, **: p≤0.01, ***: p≤0.001 compared to 0.0 μM inhibitor or SCR non-targeting siRNA control as determined by two-sided, one-sample Student’s <i>t</i>-tests.</p

Pharmacological inhibition of PI3K p110α and PI3K p110β impairs downstream signaling.

<p>(A) Western blot analysis of basal Akt/mTOR signaling activation by detection of phosphorylated downstream proteins Akt and S6 in GBM cells following treatment with increasing concentrations of PI3K p110α-specific inhibitors YM024, PIK75, or A66 (6 h). (B) Western blot analysis of phosphorylated downstream proteins Akt and S6 protein of GBM cells following treatment with increasing concentrations of the PI3K p110β-specific inhibitor TGX221 (6 h). (C) Growth factor-induced PI3K/Akt signaling activation after pretreatment of T98G and EV7 cells with PI3K p110α-specific inhibitor YM024. (D) Growth factor-induced PI3K/Akt signaling activation after pretreatment of T98G cells with PI3K p110β-specific inhibitor TGX221.</p

Expression analysis of proteins in the PI3K/Akt/mTOR signaling pathway in glioma and GBM samples.

<p>(A) IHC staining of glioma tissue microarray demonstrating increased expression of all antigens shown in GBM (WHO grade IV) compared to pilocytic astrocytoma (WHO grade I). Bars represent 100 μm. (B) Multivariable Cox-regression of IHC factors in 74 glioma patients by individually adding the immunostaining status to the clinical factors age, gender, and WHO grade. Results for p-S6 (S235/236) and S6 are shown in the upper and lower panel, respectively. HR: hazard ratio, LCL/UCL: lower/upper boundary of 95% confidence interval for HR. (C) Western blot analysis of protein levels of EGFR, PTEN, class I_A PI3K isoforms, and downstream signaling proteins Akt and S6 in human GBM cell lines and <i>ex vivo</i> cultures. Normal human brain and cerebellum tissue as well as non-transformed type II human pneumocytes were used as controls.</p

PI3K p110α-specific inhibition of T98G tumors formed on the chick chorioallantoic membrane impairs tumor growth.

<p>(A) Representative pictures of T98G tumors formed on the CAM three days post cell application (10 × magnification). Tumors were treated with PIK75 as indicated for four consecutive days. (B) Quantification of changes in tumor volume before and after PIK75 or control treatment. Lines indicate the mean of each group. *: p = 0.02 compared to control treatment as determined by two-sided, two-sample Student’s <i>t</i>-test.</p