Downregulation of transcription factor SOX2 in cancer stem cells suppresses growth and metastasis of lung cancer

Background:

The cancer stem cell hypothesis suggests that neoplastic clones are maintained exclusively by a small subpopulation of cells, which have indefinite proliferation and differentiation potentials and give rise to phenotypically diverse cancer cells. Cancer stem cells have been isolated by their ability to efflux Hoechst 33342 dye and are referred to as the ‘side population’ (SP).

Methods and results:

The Hoechst efflux assay was used to isolate and characterize the SP from murine D121 lung carcinoma cells. Here, we demonstrated that D121-SP cells contain cancer stem cell characteristics, that is, upregulation of the transcription factors SOX2 and Oct 4 in D121-SP cells. In addition, the migration of D121-SP was decreased, and apoptosis of D121-SP was upregulated following knocking down of SOX2 in D121 cells. Importantly, downregulation of SOX2 in D121 cells markedly suppressed their metastatic potential in syngeneic mice.

Conclusions:

These results suggest that the SP is an enriched source of lung tumour cells with stem cell properties and that SOX2 has an important role in maintaining stem cell properties and functions that may be a potential target for effective lung cancer therapy.

GCC expression in lymph nodes (LNs) as a significant determinant of recurrence in stage II colon cancer (CC) patients (pts)

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Background: A multi-center prospectively specified retrospective study Validating Indicators to Associate Recurrence (VITAR) is assessing the relationship between guanylyl cyclase C (GCC) gene expression in formalin fixed LNs and recurrence risk in stage II CC pts not treated with adjuvant chemotherapy. Here we report the preplanned initial analysis performed with 241 pts.

Methods: GCC mRNA was quantified by RT-qPCR using FFPE LNs tissues from untreated stage II CC pts diagnosed from 1999-2006 with at least 10 LN examined blinded to clinical outcomes. Cox regression models examined the relationship between GCC nodal status and the prespecified primary endpoint of recurrence risk.

Results: Twenty-ninepts (12%) had a disease recurrence or cancer death, median follow-up was 60 months and median LNs examined was 15. The ratio of the number of GCC+ LNs over the total number of informative LNs (LNR) significantly predicted higher recurrence risk for 84 pts classified as high risk (HR, 2.38; p=0.02). The estimated 5-yr recurrence rates were 10% and 27% for the low and high risk group, respectively. After adjusting for age, T stage, number of LNs assessed, and MMR status, the significant association remained (HR, 2.61; 95% CI, 1.17-5.83; p=0.02). In a subset of 181 pts with negative margin, T3 tumor only and ≥12 LN examined, the GCC LNR had a HR for recurrence of 5.06 (95% CI 1.61-15.91, p=0.003), translating into 5-yr recurrence rates of 4% among low risk pts and 27% for the high-risk group.

Conclusions: Our results suggest that GCC expression in LNs is a significant determinant of recurrence in appropriately staged CC pts not treated with adjuvant chemotherapy. The validation component of the study is ongoing.

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Two or three year disease-free survival (DFS) as a primary end-point in stage III adjuvant colon cancer trials with fluoropyrimidines with or without oxaliplatin or irinotecan: data from 12,676 patients from MOSAIC, X-ACT, PETACC-3, C-06, C-07 and C89803

BACKGROUND

The ACCENT group previously established disease-free survival (DFS) with 2 or 3 years median follow-up to predict 5 year overall survival (5 year OS) in stage II and III colon cancer. ACCENT further proposed (1) a stronger association between DFS and OS in stage III than II, and (2) 6 or 7 years necessary to demonstrate DFS/OS surrogacy in recent trials. The relationship between end-points in trials with oral fluoropyrimidines, oxaliplatin and irinotecan is unknown.

METHODS

Associations between the treatment effect hazard ratios (HRs) on 2 and 3 years DFS, and 5 and 6 years OS were examined in 6 phase III trials not included in prior analyses from 1997 to 2002. Individual data for 12,676 patients were analysed; two trials each tested oxaliplatin, irinotecan and oral treatment versus 5-FU/LV.

FINDINGS

Overall association between 2/3 year DFS and 5/6 year OS HRs was modest to poor (simple R² measures: 0.58-0.76, model-based R²: 0.17-0.49). In stage III patients, the association increased (model-based R² ≥ 0.79). Observed treatment effects on 2 year DFS accurately 5/6 year OS effects overall and in stage III patients.

INTERPRETATION

In recent trials of cytotoxic chemotherapy, 2 or 3 years DFS HRs are highly predictive of 5 and 6 years OS HRs in stage III but not stage II patients. In all patients the DFS/OS association is stronger for 6 year OS, thus at least 6 year follow-up is recommended to assess OS benefit. These data support DFS as the primary end-point for stage III colon cancer trials testing cytotoxic agents.

Abstract PD08-05: Longitudinal Change of Pain and Other Symptoms in Breast Cancer Patients with Anastrozole Treatment

Background About one in three breast cancer patients undergoing treated with aromatase inhibitors report problems with joint pain, some times interfering with work and other activities. We conducted a longitudinal study to characterize the course and impact of arthralgia and other symptoms during anastozole therapy by following how pain and other symptoms change during anastrozole treatment, and the impact of symptoms on patient's functioning, health-related quality of life (HRQoL), and work productivity.

Methods Two cohorts of patients were included: Cohort I recruited patients at the start of anastrozole therapy: Cohort II recruited patients at the beginning of their third year of treatment. Brief Pain Inventory and MD Anderson Symptom Inventory were used to monthly assess patients’ pain, multiple symptoms, and functioning. A single item of quality of life question and the Work Productivity and Activity Impairment Questionnaire: General Health V2.0 were used to measure patient's HRQoL and impairment of working productivity every 6 months. A joint pain self-assessment kit was used to locate the affected joints. Statistical analyses were based on the one-year follow-up data and t-test, mixed effects models, linear regression models, and correlation coefficients were used.

Results At this point in the study, thirty-eight patients have finished the one year assessment in cohort I and 37 patients in cohort II. Cohort I patients reported no or mild pain and symptoms before they started therapy. Compared to baseline, pain ratings on 0 to 10 scales significantly increased at the 5th month (4.17±3.66 vs. 1.52±2.38, p=.015) and then decreased to baseline levels at the 9th month. Similarly, patients reported higher level of distress (3.5±3.63 vs. 1.00±2.07, p=.014) and hot flashes (4.0±4.57 vs. 1.45±2.36, p=.039) at month 5 and decreased to baselines levels at month 9. Mixed effects model with the total symptom interference as the dependent variable identified that among all symptoms, pain had the greatest impact on patient functioning (p<.0001). Patients with 4 or greater pain at month 5 reported poorer HRQoL at month 6 than those reported 3 or lower pain level (5.40±1.82 vs. 8.25±2.14, p=.020). Severity of pain at month 5 was positively correlated with working productivity: impairment at work (r=.80, p=.010), overall work productivity loss (r=.81, p=.014), and activity impairment (r=.84, p=.005). During the third year of anastrozole treatment, no symptom reaches the peak level at month 5 and no significant change was found over time, as well their HRQoL and working productivity. For cohort I patients, right knee was the most affected joint and right wrist as the most affected one for cohort II patients.

Conclusion Breast cancer patients beginning analstrozole therapy reported increased pain, distress, and hot flashes at the first year of treatment, worsening around the 5th month. Increased pain negatively impacted functioning, HRQoL, and work productivity. This study indicates that symptoms related to starting anastrozole develop over the first several months of therapy and have a functional impact on patients. Symptoms emerge when patients may be less actively followed clinically. Methods of managing these symptoms need to be investigated.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr PD08-05.

Proapoptotic Bid mediates the Atr-directed DNA damage response to replicative stress

Proapoptotic BH3 interacting domain death agonist (Bid), a BH3-only Bcl-2 family member, is situated at the interface between the DNA damage response and apoptosis, with roles in death receptor-induced apoptosis as well as cell cycle checkpoints following DNA damage.(1, 2, 3) In this study, we demonstrate that Bid functions at the level of the sensor complex in the Atm and Rad3-related (Atr)-directed DNA damage response. Bid is found with replication protein A (RPA) in nuclear foci and associates with the Atr/Atr-interacting protein (Atrip)/RPA complex following replicative stress. Furthermore, Bid-deficient cells show an impaired response to replicative stress manifest by reduced accumulation of Atr and Atrip on chromatin and at DNA damage foci, reduced recovery of DNA synthesis following replicative stress, and decreased checkpoint kinase 1 activation and RPA phosphorylation. These results establish a direct role for the BH3-only Bcl-2 family member, Bid, acting at the level of the damage sensor complex to amplify the Atr-directed cellular response to replicative DNA damage.

Effect of the ratios of diameter of silo to bead on the pressure screening in granular columns

We present the apparent mass measurements at the bottom of granular packings for different bead and silo sizes. The redirection parameter K in Janssen theory is found to increase with the ratios of the diameter of the silo to the bead. We attribute this feature to the friction between the beads and the confining wall of silo; it is the role of friction that leads to variations in the shielding of vertical stresses as well as pressure screening.

Mechanism of platelet functional changes and effects of anti-platelet agents on in vivo hemostasis under different gravity conditions

Serious thrombotic and hemorrhagic problems or even fatalities evoked by either microgravity or hypergravity occur commonly in the world. We recently reported that platelet functions are inhibited in microgravity environments and activated under high-G conditions, which reveals the pathogenesis for gravity change-related hemorrhagic and thrombotic diseases. However, the mechanisms of platelet functional variations under different gravity conditions remain unclear. In this study we show that the amount of filamin A coimmunoprecipitated with GPIbalpha was enhanced in platelets exposed to modeled microgravity and, in contrast, was reduced in 8 G-exposed platelets. Hypergravity induced actin filament formation and redistribution, whereas actin filaments were reduced in platelets treated with modeled microgravity. Furthermore, intracellular Ca2+ levels were elevated by hypergravity. Pretreatment of platelets with the cell-permeable Ca2+ chelator BAPTA-AM had no effect on cytoskeleton reorganization induced by hypergravity but significantly reduced platelet aggregation induced by ristocetin/hypergravity. Two anti-platelet agents, aspirin and tirofiban, effectively reversed the shortened tail bleeding time and reduced the death rate of mice exposed to hypergravity. Furthermore, the increased P-selectin surface expression was obviously reduced in platelets from mice treated with aspirin/hypergravity compared with those from mice treated with hypergravity alone. These data suggest that the actin cytoskeleton reorganization and intracellular Ca2+ level play key roles in the regulation of platelet functions in different gravitational environments. The results with anti-platelet agents not only further confirm the activation of platelets in vivo but also suggest a therapeutic potential for hypergravity-induced thrombotic diseases.

The glycoprotein Ibalpha-von Willebrand factor interaction induces platelet apoptosis

BACKGROUND

The interaction of glycoprotein (GP) Ibalpha with von Willebrand factor (VWF) initiates platelet adhesion, and simultaneously triggers intracellular signaling cascades leading to platelet aggregation and thrombus formation. Some of the signaling events are similar to those occurring during apoptosis, however, it is still unclear whether platelet apoptosis is induced by the GPIbalpha-VWF interaction.

OBJECTIVES

To investigate whether the GPIbalpha-VWF interaction induces platelet apoptosis and the role of 14-3-3zeta in apoptotic signaling.

METHODS

Apoptotic events were assessed in platelets or Chinese hamster ovary (CHO) cells expressing wild-type (1b9) or mutant GPIb-IX interacting with VWF by flow cytometry or western blotting.

RESULTS

Ristocetin-induced GPIbalpha-VWF interaction elicited apoptotic events in platelets, including phosphatidylserine exposure, elevations of Bax and Bak, gelsolin cleavage, and depolarization of mitochondrial inner transmembrane potential. Apoptotic events were also elicited in platelets exposed to pathologic shear stresses in the presence of VWF; however, the shear-induced apoptosis was eliminated by the anti-GPIbalpha antibody AK2. Furthermore, apoptotic events occurred in 1b9 cells stimulated with VWF and ristocetin, but were significantly diminished in two CHO cell lines expressing mutant GPIb-IX with GPIbalpha truncated at residue 551 or a serine-to-alanine mutation at the 14-3-3zeta-binding site in GPIbalpha.

CONCLUSIONS

This study demonstrates that the GPIbalpha-VWF interaction induces apoptotic events in platelets, and that the association of 14-3-3zeta with the cytoplasmic domain of GPIbalpha is essential for apoptotic signaling. This finding may suggest a novel mechanism for platelet clearance or some thrombocytopenic diseases.

Gene expression profiling in the developing rat brain exposed to ketamine

Ketamine, a non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist, is associated with accelerated neuronal apoptosis in the developing rodent brain. In this study, postnatal day (PND) 7 rats were treated with 20 mg/kg ketamine or saline in six successive doses (s.c.) at 2-h intervals. Brain frontal cortical areas were collected 6 h after the last dose and RNA isolated and hybridized to Illumina Rat Ref-12 Expression BeadChips containing 22,226 probes. Many of the differentially expressed genes were associated with cell death or differentiation and receptor activity. Ingenuity Pathway Analysis software identified perturbations in NMDA-type glutamate, GABA and dopamine receptor signaling. Quantitative polymerase chain reaction (Q-PCR) confirmed that NMDA receptor subunits were significantly up-regulated. Up-regulation of NMDA receptor mRNA signaling was further confirmed by in situ hybridization. These observations support our working hypothesis that prolonged ketamine exposure produces up-regulation of NMDA receptors and subsequent over-stimulation of the glutamatergic system by endogenous glutamate, triggering enhanced apoptosis in developing neurons.

The role of calpain in the regulation of ADAM17-dependent GPIbalpha ectodomain shedding

There are evidence that both a disintegrin and metalloproteinase 17 (ADAM17) and calpain are involved in platelet glycoprotein (GP)Ibalpha ectodomain cleavage. However, the relationship between the two enzymes in the shedding process remains unclear. Here we show that calcium ionophore A23187- and alpha-thrombin-induced GPIbalpha shedding is completely inhibited by the metalloproteinase inhibitor GM6001, whereas it is only partially inhibited by calpain inhibitors. Calpain activator dibucaine-induced GPIbalpha shedding was completely inhibited by both metalloproteinase and calpain inhibitors. On the other hand, calpain inhibitors did not inhibit GPIbalpha shedding induced by the reagents that specifically activate ADAM17. Furthermore, A23187-induced GPIbalpha shedding in Chinese hamster ovary cells expressing wild-type or mutant GPIb-IX was also partially inhibited by calpain inhibitors and almost completely inhibited by GM6001. Therefore, these data indicate that calpain plays an important role in the regulation of ADAM17-dependent GPIbalpha ectodomain shedding in both platelets and nucleated cells.

Novel anti-prostate cancer curcumin analogues that enhance androgen receptor degradation activity

The androgen receptor (AR) plays a crucial role in the physiological and pathological functions of androgen. As a transcription factor, the AR modulates androgen activity by regulating the transcription of target genes that are involved in numerous physiological functions and pathological disorders, such as acne vulgaris, androgenetic alopecia, benign prostate hyperplasia (BPH), and prostate cancers. Although many natural and synthetic curcumin analogues have been reported to possess anticancer activity through a common cytotoxic property against proliferating tumor cells, none has been reported to inhibit cancer cell growth through a more specific mechanism or target in the cancer cells. Recently, new curcumin analogues were studied extensively regarding their synthesis, structure-activity (i.e., anticancer activity) relationships, and mechanism of action. These compounds, such as ASC-J9 and its analogues (3 and 4), have now been shown to inhibit prostate cancer proliferation through a novel mechanism of enhancing AR degradation.