Expression of NRG1 and its receptors in human bladder cancer

Background:

Therapies targeting ERBB2 have shown success in the clinic. However, response is not determined solely by expression of ERBB2. Levels of ERBB3, its preferred heterodimerisation partner and ERBB ligands may also have a role.

Methods:

We measured NRG1 expression by real-time quantitative RT–PCR and ERBB receptors by western blotting and immunohistochemistry in bladder tumours and cell lines.

Results:

NRG1α and NRG1β showed significant coordinate expression. NRG1β was upregulated in 78% of cell lines. In tumours, there was a greater range of expression with a trend towards increased NRG1α with higher stage and grade. Increased expression of ERBB proteins was detected in 15% (EGFR), 20% (ERBB2), 41% (ERBB3) and 0% (ERBB4) of cell lines. High EGFR expression was detected in 28% of tumours, associated with grade and stage (P=0.05; P=0.04). Moderate or high expression of ERBB2 was detected in 22% and was associated with stage (P=0.025). Cytoplasmic ERBB3 was associated with high tumour grade (P=0.01) and with ERBB2 positivity. In cell lines, NRG1β expression was significantly inversely related to ERBB3, but this was not confirmed in tumours.

Conclusion:

There is a wide spectrum of NRG1 and ERBB receptor expression in bladder cancer. In advanced tumours, EGFR, ERBB2 and ERBB3 upregulation is common and there is a relationship between expression of ERBB2 and ERBB3 but not the NRG1 ligand.     

Oestrogen receptor-�� contributes to the regulation of the hedgehog signalling pathway in ER��-positive gastric cancer

Background:

Oestrogen receptor-alpha (ERα) is highly expressed in diffuse-type gastric cancer and oestrogen increases the proliferation of ERα-positive gastric cancer. However, a detailed mechanism by which oestrogen increases the proliferation of these cells is still unclear.

Methods:

We used 17-β-oestradiol (E2) as a stimulator against the ERα pathway. Pure anti-oestrogen drug ICI 182 780 (ICI) and small interfering RNA against ERα (ERα siRNA) were used as inhibitors. Cyclopamine (Cyc) was used as the hedgehog (Hh) pathway inhibitor. Two human ERα-positive gastric cancer cells were used as target cells. Effects of the stimulator and inhibitor on E2-induced cell proliferation were also examined.

Results:

In ERα-positive cells, E2 increased not only cell proliferation but also one of the ligands of the Hh pathway, Shh expression. 17-β-Oestradiol-induced cell proliferation was suppressed by ICI, ERα siRNA or Cyc. The increased expression of Shh induced by E2 was suppressed by ICI and ERα siRNA but not by Cyc. Furthermore, recombinant Shh activated the Hh pathway and increased cell proliferation, whereas anti-Shh antibody suppressed E2-induced cell proliferation. When a relationship between ERα and Shh expressions was analysed using surgically resected gastric cancer specimens, a positive correlation was found, suggesting a linkage between the ERα and Hh pathways.

Conclusion:

Our data indicate that activation of the ERα pathway promotes cell proliferation by activating the Hh pathway in a ligand-dependent manner through Shh induction of ERα-positive gastric cancer.     

Expression of sphingosine 1-phosphate receptor 4 and sphingosine kinase 1 is associated with outcome in oestrogen receptor-negative breast cancer

Background:

We previously reported that sphingosine 1-phosphate receptor 4 (S1P₄) is expressed and stimulates the ERK-1/2 pathway via a human epidermal growth factor receptor 2 (HER2)-dependent mechanism in oestrogen receptor-negative (ER⁻) MDA-MB-453 breast cancer cells.

Methods:

Clinical relevance of S1P₄ and sphingosine kinase 1 (SK1, which catalyses the formation of S1P) was assessed in a cohort of 140 ER⁻ breast tumours by immunohistochemistry (IHC) and the weighted histoscore method. Additional evidence for a functional interaction between S1P₄ and SK1 and between HER2 and SK1 was obtained using MDA-MB-453 cells.

Results:

High S1P₄ expression is associated with shorter disease-free (P=0.014) and disease-specific survival (P=0.004), and was independent on multivariate analysis. In addition, patients with tumours that contain high and low levels of SK1 and S1P₄, respectively, have a significantly shorter disease-free survival (P=0.043) and disease-specific survival (P=0.033) compared with patients whose tumours contain both low S1P₄ and SK1 levels. In addition, high tumour expression of SK1 was significantly associated with shorter disease-specific survival (P=0.0001) in patients with HER2-positive tumours. Treatment of MDA-MB-453 cells with the SK1 inhibitor, SKi (2-(p-hydroxyanilino)-4-(p-chlorophenyl)thiazole) reduced the basal and S1P/S1P₄-induced activation of ERK-1/2 and altered HER2 trafficking in these cells.

Conclusion:

These findings highlight an important role for S1P₄ and SK1 in ER⁻ breast cancer progression.     

Oestrogen receptors β1 and βcx have divergent roles in breast cancer survival and lymph node metastasis

Background:

The expression of oestrogen receptor (ER) α characterises a subset of breast cancers associated with good response to endocrine therapy. However, the clinical significance of the second ER, ERβ1, and its splice variant ERβcx is still unclear.

Methods:

We here report an assessment of ERα, ERβ1 and ERβcx by immunohistochemistry using quantitative digital image analysis of 340 primary tumours and corresponding sentinel lymph nodes.

Results:

No differences were seen in ER levels in primary tumours vs lymph node metastases. ERβ1 and ERβcx were equally distributed among age groups and tumour histological grades. Loss of ERβ1 in the primary tumour was strongly associated with poor survival. Its prognostic impact was particularly evident in young patients and in high-grade tumours. The worst outcome was seen in the tumours lacking both ERα and ERβ1. ERβcx expression in the primary tumour correlated with a higher risk of lymph node metastasis, and with poor survival when expressed in sentinel node lymphocytes.

Conclusions:

Our study reveals highly significant although antagonising roles of ERβ1 and ERβcx in breast cancer. Consequently, we suggest that the histopathological assessment of ERβ1 is of value as a prognostic and potentially predictive biomarker.     

Targeting both Notch and ErbB-2 signalling pathways is required for prevention of ErbB-2-positive breast tumour recurrence

Background:

We reported that Notch-1, a potent breast oncogene, is activated in response to trastuzumab and contributes to trastuzumab resistance in vitro. We sought to determine the preclinical benefit of combining a Notch inhibitor (γ-secretase inhibitor (GSI)) and trastuzumab in both trastuzumab-sensitive and trastuzumab-resistant, ErbB-2-positive, BT474 breast tumours in vivo. We also studied if the combination therapy of lapatinib plus GSI can induce tumour regression of ErbB-2-positive breast cancer.

Methods:

We generated orthotopic breast tumour xenografts from trastuzumab- or lapatinib-sensitive and trastuzumab-resistant BT474 cells. We investigated the antitumour activities of two distinct GSIs, LY 411 575 and MRK-003, in vivo.

Results:

Our findings showed that combining trastuzumab plus a GSI completely prevented (MRK-003 GSI) or significantly reduced (LY 411 575 GSI) breast tumour recurrence post-trastuzumab treatment in sensitive tumours. Moreover, combining lapatinib plus MRK-003 GSI showed significant reduction of tumour growth. Furthermore, a GSI partially reversed trastuzumab resistance in resistant tumours.

Conclusion:

Our data suggest that a combined inhibition of Notch and ErbB-2 signalling pathways could decrease recurrence rates for ErbB-2-positive breast tumours and may be beneficial in the treatment of recurrent trastuzumab-resistant disease.     

Multi-colour FISH in oesophageal adenocarcinoma—predictors of prognosis independent of stage and grade

Background:

Oesophageal adenocarcinoma or Barrett''s adenocarcinoma (EAC) is increasing in incidence and stratification of prognosis might improve disease management. Multi-colour Fluorescence in situ hybridisation (FISH) investigating ERBB2, MYC, CDKN2A and ZNF217 has recently shown promising results for the diagnosis of dysplasia and cancer using cytological samples.

Methods:

To identify markers of prognosis we targeted four selected gene loci using multi-colour FISH applied to a tissue microarray containing 130 EAC samples. Prognostic predictors (P1, P2, P3) based on genomic copy numbers of the four loci were statistically assessed to stratify patients according to overall survival in combination with clinical data.

Results:

The best stratification into favourable and unfavourable prognoses was shown by P1, percentage of cells with less than two ZNF217 signals; P2, percentage of cells with fewer ERBB2- than ZNF217 signals; and P3, overall ratio of ERBB2-/ZNF217 signals. Median survival times for P1 were 32 vs 73 months, 28 vs 73 months for P2; and 27 vs 65 months for P3. Regarding each tumour grade P2 subdivided patients into distinct prognostic groups independently within each grade, with different median survival times of at least 35 months.

Conclusions:

Cell signal number of the ERBB2 and ZNF217 loci showed independence from tumour stage and differentiation grade. The prognostic value of multi-colour FISH-assays is applicable to EAC and is superior to single markers.     

CXCR4 activation maintains a stem cell population in tamoxifen-resistant breast cancer cells through AhR signalling

Background:

Tamoxifen is commonly used for breast cancer therapy. However, tamoxifen resistance is an important clinical problem. Continuous treatment with conventional therapy may contribute to cancer progression in recurring cancers through the accumulation of drug-resistant cancer progenitors.

Methods:

To investigate signalling mechanisms important for the maintenance and viability of drug-resistant cancer progenitors, we used microarray analysis, PCR array for genes involved in cancer drug resistance and metabolism, flow cytometry, soft agar colony formation assay, in vivo tumourigenicity assay and immunohistochemical analysis using tamoxifen-sensitive and tamoxifen-resistant breast cancer MCF7 cells.

Results:

Downregulation of CXCR4 signalling by small molecule antagonist AMD3100 specifically inhibits growth of progenitor cell population in MCF7(TAM-R) cells both in vitro and in vivo. Microarray analysis revealed aryl hydrocarbon receptor (AhR) signalling as one of the top networks that is differentially regulated in MCF7(TAM-R) and MCF7 xenograft tumours treated with AMD3100. Further, small molecule antagonists of AhR signalling specifically inhibit the progenitor population in MCF7(TAM-R) cells and growth of MCF7(TAM-R) xenografts in vivo.

Conclusion:

The chemokine receptor CXCR4 maintains a cancer progenitor population in tamoxifen-resistant MCF7 cells through AhR signalling and could be a putative target for the treatment of tamoxifen-resistant breast cancers.     

Androgen receptor expression predicts beneficial tamoxifen response in oestrogen receptor-α-negative breast cancer

Background:

Although the androgen receptor (AR) is frequently expressed in breast cancer, its relevance in the disease is not fully understood. In addition, the relevance of AR in determining tamoxifen treatment efficiency requires evaluation.

Purpose:

To investigate the tamoxifen predictive relevance of the AR protein expression in breast cancer.

Methods

Patients were randomised to tamoxifen 40 mg daily for 2 or 5 years or to no endocrine treatment. Mean follow-up was 15 years. Hazard ratios were calculated with recurrence-free survival as end point.

Results:

In patients with oestrogen receptor (ER)-negative tumours, expression of AR predicted decreased recurrence rate with tamoxifen (hazard ratio (HR)=0.34; 95% confidence interval (CI)=0.14–0.81; P=0.015), whereas the opposite was seen in the AR− group (HR=2.92; 95% CI=1.16–7.31; P=0.022). Interaction test was significant P<0.001. Patients with triple-negative and AR+ tumours benefitted from tamoxifen treatment (HR=0.12; 95% CI=0.014–0.95 P=0.044), whereas patients with AR− tumours had worse outcome when treated with tamoxifen (HR=3.98; 95% CI=1.32–12.03; P=0.014). Interaction test was significant P=0.003. Patients with ER+ tumours showed benefit from tamoxifen treatment regardless of AR expression.

Conclusions:

AR can predict tamoxifen treatment benefit in patients with ER− tumours and triple-negative breast cancer.     

Lapatinib monotherapy in patients with relapsed, advanced, or metastatic breast cancer: efficacy, safety, and biomarker results from Japanese patients phase II studies

Background:

HER2-positive metastatic breast cancer (MBC) relapsing after trastuzumab-based therapy may require continued HER2 receptor inhibition to control the disease and preserve the patients'' quality-of-life. Efficacy and safety of lapatinib monotherapy was evaluated in Japanese breast cancer patients after trastuzumab-based therapies.

Methods:

In studies, EGF100642 and EGF104911 evaluated the efficacy and safety of oral lapatinib given 1500 mg once daily in patients with advanced or MBC. All patients progressed on anthracyclines and taxanes; HER2-positive patients had also progressed on trastuzumab.

Results:

For HER2-positive tumours (n=100), objective response rate was 19.0% (95% confidence interval (CI): 11.8–28.1) and clinical benefit rate (CBR) was 25.0% (95% CI: 16.9–34.7). One out of 22 HER2-negative tumour was documented as complete response (n=22). The median time-to-progression (TTP) in the HER2-positive and HER2-negative groups was 13.0 and 8.0 weeks (P=0.007); median overall survival was 58.3 and 40.0 weeks, respectively. The most frequent adverse event was diarrhoea. TTP and CBR were significantly associated with HER2 expression. Patients with tumours harbouring an H1047R PIK3CA mutation or low expression of PTEN derived clinical benefit from lapatinib.

Conclusion:

Lapatinib monotherapy had shown anti-tumour activity in Japanese patients with HER2-positive MBC that relapsed after trastuzumab-based therapy, including those with brain metastases. Patients benefiting from lapatinib may have biomarker profiles differing from that reported for trastuzumab.     

Side-population cells in luminal-type breast cancer have tumour-initiating cell properties, and are regulated by HER2 expression and signalling

Background:

The expression of side-population (SP) cells and their relation to tumour-initiating cells (T-ICs) have been insufficiently studied in breast cancer (BC). We therefore evaluated primary cell cultures derived from patients and a panel of human BC cell lines with luminal- or basal-molecular signatures for the presence of SP and BC stem cell markers.

Methods:

The SPs from luminal-type BC were analysed for BC T-IC characteristics, including human epidermal growth factor receptor 2 (HER2), ERα, IGFBP7 expression and their ability to initiate tumours in non-obese diabetic severe combined immunodeficiency (NOD/SCID) mice. Pharmacological modulators were used to assess the effects of HER2 signalling and breast cancer-resistance protein (BCRP) expression on SPs.

Results:

The SP was more prevalent in the luminal subtype of BC compared with the basal subtype. HER2 expression was significantly correlated with the occurrence of an SP (r²=0.75, P=0.0003). Disappearance of SP in the presence of Ko143, a specific inhibitor of the ATP-binding cassette transporter BCRP, suggests that BCRP is the predominant transporter expressed in this population. The SP also decreased in the presence of HER2 signalling inhibitors AG825 or trastuzumab, strengthening the notion that HER2 contributed to the SP phenotype, likely through downstream AKT signalling. The SP cells from luminal-type MCF-7 cells with enforced expression of HER2, and primary cells with luminal-like properties from a BC patient, displayed enrichment in cells capable of repopulating tumours in NOD/SCID mice. Engraftment of SP cells was inhibited by pretreatment with AG825 or by in vivo treatment with trastuzumab.

Interpretation:

Our findings indicate an important role of HER2 in regulating SP and hence T-ICs in BC, which may account for the poor responsiveness of HER2-positive BCs to chemotherapy, as well as their aggressiveness.     

Frequency of HER2 expression of circulating tumour cells in patients with metastatic or recurrent gastrointestinal cancer

Background:

The clinical significance of circulating tumour cell (CTC) detection in gastrointestinal (GI) cancer remains controversial and the molecular biological characteristics of CTCs are poorly understood.

Methods:

A total of 87 patients with metastatic or recurrent GI cancer were prospectively enrolled. Circulating tumour cells and their HER2 status were assessed using the CellSearch System.

Results:

Among the 62 CTC-positive cases, we found 22 discordant cases (35.5%). Among the HER2-negative primary tumours, 17 of 54 developed HER2-positive CTCs. Five of eight had HER2-negative CTCs among the HER2-positive primary tumours.

Conclusion:

The findings in the current study suggest that it is critical to evaluate the HER2 status of not only the primary tumour but also the CTCs because the metastasising tumour cells are the primary target of systemic therapy.     

Brain metastases free survival differs between breast cancer subtypes

Background:

Brain metastases (BM) are frequently diagnosed in patients with HER-2-positive metastatic breast cancer; in addition, an increasing incidence was reported for triple-negative tumours. We aimed to compare brain metastases free survival (BMFS) of breast cancer subtypes in patients treated between 1996 until 2010.

Methods:

Brain metastases free survival was measured as the interval from diagnosis of extracranial breast cancer metastases until diagnosis of BM. HER-2 status was analysed by immunohistochemistry and reanalysed by fluorescent in situ hybridisation if a score of 2+ was gained. Oestrogen-receptor (ER) and progesterone-receptor (PgR) status was analysed by immunohistochemistry. Brain metastases free survival curves were estimated with the Kaplan–Meier method and compared with the log-rank test.

Results:

Data of 213 patients (46 luminal/124 HER-2/43 triple-negative subtype) with BM from breast cancer were available for the analysis. Brain metastases free survival differed significantly between breast cancer subtypes. Median BMFS in triple-negative tumours was 14 months (95% CI: 11.34–16.66) compared with 18 months (95% CI: 14.46–21.54) in HER-2-positive tumours (P=0.001) and 34 months (95% CI: 23.71–44.29) in luminal tumours (P=0.001), respectively. In HER-2-positive patients, co-positivity for ER and HER-2 prolonged BMFS (26 vs 15 m; P=0.033); in luminal tumours, co-expression of ER and PgR was not significantly associated with BMFS. Brain metastases free survival in patients with lung metastases was significantly shorter (17 vs 21 months; P=0.014).

Conclusion:

Brain metastases free survival in triple-negative breast cancer, as well as in HER-2-positive/ER-negative, is significantly shorter compared with HER-2/ER co-positive or luminal tumours, mirroring the aggressiveness of these breast cancer subtypes.     

Fulvestrant induces resistance by modulating GPER and CDK6 expression: implication of methyltransferases,deacetylases and the hSWI/SNF chromatin remodelling complex

Background:

Breast cancer is the leading cause of cancer death in women living in the western hemisphere. Despite major advances in first-line endocrine therapy of advanced oestrogen receptor (ER)-positive breast cancer, the frequent recurrence of resistant cancer cells represents a serious obstacle to successful treatment. Understanding the mechanisms leading to acquired resistance, therefore, could pave the way to the development of second-line therapeutics. To this end, we generated an ER-positive breast cancer cell line (MCF-7) with resistance to the therapeutic anti-oestrogen fulvestrant (FUL) and studied the molecular changes involved in resistance.

Methods:

Naive MCF-7 cells were treated with increasing FUL concentrations and the gene expression profile of the resulting FUL-resistant strain (FR.MCF-7) was compared with that of naive cells using GeneChip arrays. After validation by real-time PCR and/or western blotting, selected resistance-associated genes were functionally studied by siRNA-mediated silencing or pharmacological inhibition. Furthermore, general mechanisms causing aberrant gene expression were investigated.

Results:

Fulvestrant resistance was associated with repression of GPER and the overexpression of CDK6, whereas ERBB2, ABCG2, ER and ER-related genes (GREB1, RERG) or genes expressed in resistant breast cancer (BCAR1, BCAR3) did not contribute to resistance. Aberrant GPER and CDK6 expression was most likely caused by modification of DNA methylation and histone acetylation, respectively. Therefore, part of the resistance mechanism was loss of RB1 control. The hSWI/SNF (human SWItch/Sucrose NonFermentable) chromatin remodelling complex, which is tightly linked to nucleosome acetylation and repositioning, was also affected, because as a stress response to FUL treatment-naive cells altered the expression of five subunits within a few hours (BRG1, BAF250A, BAF170, BAF155, BAF47). The aberrant constitutive expression of BAF250A, BAF170 and BAF155 and a deviant stress response of BRG1, BAF170 and BAF47 in FR.MCF-7 cells to FUL treatment accompanied acquired FUL resistance. The regular and aberrant expression profiles of BAF155 correlated directly with that of CDK6 in naive and in FR.MCF-7 cells corroborating the finding that CDK6 overexpression was due to nucleosome alterations.

Conclusion:

The study revealed that FUL resistance is associated with the dysregulation of GPER and CDK6. A mechanism leading to aberrant gene expression was most likely unscheduled chromatin remodelling by hSWI/SNF. Hence, three targets should be conceptually addressed in a second-line adjuvant therapy: the catalytic centre of SWI/SNF (BRG1) to delay the development of FUL resistance, GPER to increase sensitivity to FUL and the reconstitution of the RB1 pathway to overcome resistance.     

Src,a potential target for overcoming trastuzumab resistance in HER2-positive breast carcinoma

Background:

Src is a non-receptor tyrosine kinase involved in signalling and crosstalk between growth-promoting pathways. We aim to investigate the relationship of active Src in response to trastuzumab of HER2-positive breast carcinomas.

Methods:

We selected 278 HER2-positive breast cancer patients with (n=154) and without (n=124) trastuzumab treatment. We performed immunohistochemistry on paraffin-embedded tissue microarrays of active Src and several proteins involved in the PI3K/Akt/mTOR pathway, PIK3CA mutational analysis and in vitro studies (SKBR3 and BT474 cancer cells). The results were correlated with clinicopathological factors and patients'' outcome.

Results:

Increased pSrc-Y416 was demonstrated in trastuzumab-resistant cells and in 37.8% of tumours that correlated positively with tumour size, necrosis, mitosis, metastasis to the central nervous system, p53 overexpression and MAPK activation but inversely with EGFR and p27. Univariate analyses showed an association of increased active Src with shorter survival in patients at early stage with HER2/hormone receptor-negative tumours treated with trastuzumab.

Conclusions:

Src activation participates in trastuzumab mechanisms of resistance and indicates poor prognosis, mainly in HER2/hormone receptor-negative breast cancer. Therefore, blocking this axis may be beneficial in those patients.     

Loss of GPER identifies new targets for therapy among a subgroup of ERα-positive endometrial cancer patients with poor outcome

Background:

The G protein-coupled oestrogen receptor, GPER, has been suggested as an alternative oestrogen receptor. Our purpose was to investigate the potential of GPER as a prognostic and predictive marker in endometrial carcinoma and to search for new drug candidates to improve treatment of aggressive disease.

Materials and method:

A total of 767 primary endometrial carcinomas derived from three patient series, including an external dataset, were studied for protein and mRNA expression levels to investigate and validate if GPER loss identifies poor prognosis and new targets for therapy in endometrial carcinoma. Gene expression levels, according to ERα/GPER status, were used to search the connectivity map database for small molecular inhibitors with potential for treatment of metastatic disease for receptor status subgroups.

Results:

Loss of GPER protein is significantly correlated with low GPER mRNA, high FIGO stage, non-endometrioid histology, high grade, aneuploidy and ERα loss (all P-values ⩽0.05). Loss of GPER among ERα-positive patients identifies a subgroup with poor prognosis that until now has been unrecognised, with reduced 5-year survival from 93% to 76% (P=0.003). Additional loss of GPER from primary to metastatic lesion counterparts further supports that loss of GPER is associated with disease progression.

Conclusion:

These results support that GPER status adds clinically relevant information to ERα status in endometrial carcinoma and suggest a potential for new inhibitors in the treatment of metastatic endometrial cancers with ERα expression and GPER loss.     

Regulation of tamoxifen sensitivity by a PAK1–EBP1 signalling pathway in breast cancer

Background:

EBP1, an ErbB3-binding protein, sensitises breast cancer cells to tamoxifen in part by decreasing ErbB2 protein levels. The p21-regulated serine/threonine kinase PAK1, implicated in tamoxifen resistance, phosphorylates EBP1 in vitro and in vivo at T261. Phosphorylation of EBP1 at this site induces tamoxifen resistance. We thus postulated that inhibition of PAK1 activity, by restoring EBP1 function, could ameliorate the hormone refractory phenotype of ErbB2-overexpressing breast cancer cells.

Methods:

Effects of EBP1 on ErbB2 levels were measured by western blotting. Effects of EBP1 and IPA-3 on tamoxifen sensitivity were measured using a tetrazolium based cell viability assay.

Results:

Transient transfection studies indicated that an EBP1 T261E mutant, which mimics EPB1 phosphorylated by PAK1, increased ErbB2 protein levels. An EBP1 T261A mutant, unable to be phosphorylated by PAK1, ameliorated PAK1-induced tamoxifen resistance, suggesting that phosphorylation of EBP1 by PAK1 contributes to tamoxifen resistance. We then tested if pharmacological inhibition of PAK1 activity might render hormone resistant cells, which endogenously overexpress PAK1, tamoxifen sensitive. IPA-3, a specific small MW PAK1 inhibitor, sensitised cells to tamoxifen only when EBP1 was ectopically expressed. IPA had no effect on tamoxifen resistance in T47D cells in which EBP1 protein had been ablated by shRNA. The IPA-induced increase in tamoxifen sensitivity was accompanied by a decrease in ErbB2 levels only in EBP1-overexpressing cells.

Conclusion:

These studies suggest that phosphorylation of EBP1 may be one mechanism of PAK1-induced hormone resistance and that PAK1 inhibitors may be useful in cells in which EBP1 is overexpressed.     

CD10 as a novel marker of therapeutic resistance and cancer stem cells in head and neck squamous cell carcinoma

Background:

Cancer stem cells (CSCs) are responsible for treatment failure. However, their identification and roles in resistance are not well established in head and neck squamous cell carcinoma (HNSCC).

Methods:

Three HNSCC cell lines (FaDu, Detroit562 and BICR6) were treated with cisplatin or radiation. Cell surface antigens were analysed by LyoPlate, a novel cell surface antigen array. The expression levels of antigens highly expressed after treatments were further compared between cisplatin-resistant Detroit562 cells and its parental line. Association of the candidate antigen with CSCs properties, namely sphere formation and in vivo tumourigenicity, was also examined.

Results:

CD10, CD15s, CD146 and CD282 were upregulated across the treated cell lines, while the increased expression of CD10 was prominent in the cisplatin-resistant cell line. Isolation mediated by FACS revealed that the CD10-positive subpopulation was more refractory to cisplatin, fluorouracil and radiation than the CD10-negative subpopulation. It also showed an increased ability to form spheres in vitro and tumours in vivo. Moreover, the CD10-positive subpopulation expressed the CSC marker OCT3/4 at a higher level than that in the CD10-negative subpopulation.

Conclusions:

CD10 is associated with therapeutic resistance and CSC-like properties of HNSCC. CD10 may serve as a target molecule in the treatment of refractory HNSCC.     

Effect of (Neo)adjuvant zoledronic acid on disease-free and overall survival in clinical stage II/III breast cancer

Background:

Despite neoadjuvant/adjuvant chemotherapy, women with resectable stage II/III breast cancer (BC) have high risk of recurrent disease. Recent data suggest that zoledronic acid (ZOL) therapy concurrent with adjuvant treatments may improve cancer-related outcomes in patients with BC.

Methods:

Disease-free survival (DFS; secondary end point) and overall survival (OS; tertiary end point) were evaluated in 119 women with stage II/III BC randomised to intravenous ZOL 4 mg every 3 weeks for 1 year or no ZOL (control) starting with the first chemotherapy cycle.

Results:

At 61.9 months'' median follow-up, there was no significant difference in recurrence or survival between study arms. However, time to recurrence or death (DFS) was significantly different between subgroups defined by oestrogen receptor (ER) status (interaction P=0.010 for DFS and 0.025 for OS). Hazard ratios (HRs) for disease recurrence and death were significantly less among patients with ER-negative (ER⁻) tumours who received ZOL vs no ZOL (DFS: HR=0.361, 95% confidence interval (CI) 0.148, 0.880; OS: HR=0.375, 95% CI 0.143, 0.985).

Conclusion:

ZOL administered with chemotherapy may improve DFS and OS in a subset of BC patients with ER⁻ tumours. This study was not powered to compare subgroups of patients; thus, these findings should be considered hypothesis generating.