No abstract

Imbalance of signals that control cell survival and death results in pathologies, including cancer and neurodegeneration. Two pathways that are integral to setting the balance between cell survival and cell death are controlled by lipid-activated protein kinase B (PKB)/Akt and Ca 2؉ . PKB elicits its effects through the phosphorylation and inactivation of proapoptotic factors. Ca 2؉ stimulates many prodeath pathways, among which is mitochondrial permeability transition. We identified Ca 2؉ release through inositol 1,4,5-trisphosphate receptor (InsP3R) intracellular channels as a prosurvival target of PKB. We demonstrated that in response to survival signals, PKB interacts with and phosphorylates InsP3Rs, significantly reducing their Ca 2؉ release activity. Moreover, phosphorylation of InsP3Rs by PKB reduced cellular sensitivity to apoptotic stimuli through a mechanism that involved diminished Ca 2؉ flux from the endoplasmic reticulum to the mitochondria. In glioblastoma cells that exhibit hyperactive PKB, the same prosurvival effect of PKB on InsP3R was found to be responsible for the insensitivity of these cells to apoptotic stimuli. We propose that PKB-mediated abolition of InsP3-induced Ca 2؉ release may afford tumor cells a survival advantage.signaling ͉ cell death ͉ cancer P rotein kinase B (PKB) is a central player in regulating many signaling pathways controlling cell metabolism, growth, and survival (1, 2). PKB elicits these effects by phosphorylating and regulating the activity of downstream targets such as glycogen synthase kinase 3␤ and Bad, or via transcription factors such as Forkhead (1, 3). Because of this critical role of PKB, gain or loss of function is manifest in major disease phenotypes such as cancer and type 2 diabetes (1, 4-6).Ca 2ϩ released from the endoplasmic reticulum (ER) through inositol 1,4,5-trisphosphate (InsP 3 ) receptors (InsP 3 Rs) plays a key role in regulating physiological processes (7). However, under pathological conditions, InsP 3 -induced Ca 2ϩ release (IICR) can be subverted to promote cell death pathways (8-10). The importance of IICR in cell death is underlined by the uncovering of functional interactions with a number of proteins with known proapoptotic and antiapoptotic activity. Notable among these are Bcl-2, Bcl-X L , and cytochrome c (11)(12)(13)(14). PKB has also recently been shown to phosphorylate the InsP 3 R, with consequences for cell survival (15).We investigated whether cross-talk between the phosphatidylinositol 3-kinase (PI3K)/PKB and InsP 3 /Ca 2ϩ signaling pathways regulated how cells responded to death-inducing stimuli. We determined that PKB-mediated phosphorylation of InsP 3 R results in a decrease in the magnitude of IICR and resultant flux of Ca 2ϩ from the ER to mitochondria. Moreover, we show that this decrease in Ca 2ϩ flux caused by PKB-mediated phosphorylation of InsP 3 Rs contributes to protection from the effects of apoptotic stimuli. This prosurvival action of PKB was also apparent in a glioblastoma cell line (U87) that exhibits increase...

Although pertuzumab has some activity in patients with HER2-positive breast cancer that progressed during therapy with trastuzumab, the combination of pertuzumab and trastuzumab seems to be more active than monotherapy.

The vasomotor properties of isolated aortae and mesenteric arteries of insulin-resistant ob/ob and 57CBL/6J mice were compared in organ bath studies. Vessels from ob/ob mice were more sensitive to phenylephrine. Pretreatment with L-NAME caused similar leftward shifts of the phenylephrine concentration response curves in diabetic and non-diabetic vessels. The ob/ob aortae contracted in response to phenylephrine with roughly twice the force while they were not stiffer than control aortae. L-NAME caused a greater percentage increase in maximal force in the control than in the ob/ob tissue. Denudation potentiated force in the control aortae, but not in the ob/ob aortae. Endothelium-dependent relaxation in the ob/ob aortae and mesenteric arteries was impaired as manifested by a decreased sensitivity and maximal relaxation to acetylcholine, while the aortic basal eNOS mRNA levels did not differ between the two strains. In addition, ob/ob aortae were less sensitive to the nitric oxide donor sodium nitroprusside. Inhibition of endogenous prostaglandin synthesis with indomethacin (10 µM) partly normalized the contractile response of the ob/ob aortae and enhanced their endothelium-dependent relaxation. Neither blockade of endothelin-1 receptors (bosentan, 10 µM) nor PKC inhibition (calphostin, 1 µM) affected the contractile response to phenylephrine in the mouse aortae of either strain. In conclusion, vascular dysfunction in the aorta and mesenteric artery of ob/ob mice are due to increased smooth muscle contractility and impaired dilation but not to changes in elasticity of the vascular wall. Endothelium-produced prostaglandins contribute to the increased vasoconstriction.

BackgroundNeoSphere showed significantly higher pathologic complete response (pCR) with neoadjuvant pertuzumab, trastuzumab, and docetaxel compared with trastuzumab plus docetaxel, pertuzumab plus trastuzumab, or pertuzumab plus docetaxel. We assessed associations between human epidermal growth factor receptor 2 (HER2) pathway-related biomarkers and clinical outcome in response to these regimens.MethodsTumor, serum, and whole blood samples were collected at baseline and post neoadjuvant treatment before surgery. Associations between biomarkers and pCR, and between biomarkers and clinical variables were assessed in the overall and estrogen receptor (ER)-positive and ER-negative populations. Changes in serum marker levels between baseline and post-neoadjuvant treatment were examined.ResultsNo markers were associated with pCR across all groups; however, significant associations were observed for two markers in individual groups. High HER2 was significantly associated with higher pCR rates (P = 0.001) and a significant treatment interaction (P = 0.0236) with pertuzumab, trastuzumab, and docetaxel (odds ratio 2.07, P = 0.01). Low serum transforming growth factor alpha (TGFα) was associated with higher pCR rates with pertuzumab plus trastuzumab (P = 0.04) without a significant treatment interaction. Presence of truncated HER2 did not affect pCR. A non-significant decreased pCR benefit was observed consistently across groups in patients with mutated PIK3CA while the treatment benefit from pertuzumab was maintained when comparing the trastuzumab plus docetaxel and pertuzumab, trastuzumab, and docetaxel groups. Notably, PIK3CA exon 9 mutations were associated with residual disease (pooled groups), which was not found for exon 20 mutations. Serum HER2 extracellular domain levels were significantly increased between baseline and post-neoadjuvant treatment in the non-trastuzumab-treated group, and decreased in the trastuzumab-containing groups (likely due to trastuzumab’s mechanism of action). Differences in biomarker profiles according to ER status were observed.ConclusionsThe observed associations of HER2 protein levels with sensitivity to pertuzumab, and of PIK3CA exon 9 mutation to lack of sensitivity to HER2-targeted monoclonal antibody treatment, warrant further investigation. Previously reported findings of truncated forms of HER2 as resistance markers to HER2-targeted treatment could not be confirmed in NeoSphere. Conventional HER2 assessment should continue and HER2 remains the only biomarker suitable for patient selection in this population.Trial registrationClinicaltrials.gov, NCT00545688. Registered on 16 October 2007.Electronic supplementary materialThe online version of this article (doi:10.1186/s13058-017-0806-9) contains supplementary material, which is available to authorized users.