Nuclear factor erythroid 2-related factor 2 modulates HER4 receptor in ovarian cancer cells to influence their sensitivity to tyrosine kinase inhibitors

Aim:

Nuclear factor erythroid 2-related factor 2 (NRF2) is a key component in the cell’s response to oxidative and electrophilic stress and is a transcription factor regulating the expression of a collection of anti-oxidative and cytoprotective genes. Human epidermal growth factor receptor 4 (HER4/erbB4) regulates growth and differentiation in many cancer types. Here, NRF2 and HER4 receptor interactions were investigated in a panel of ovarian cancer cell lines.

Methods:

Pharmacological [tert-butylhydroquinone (tBHQ) and retinoid/rexinoid, bexarotene] and genetic [small interfering RNA (siRNA)] manipulations were used to activate or inhibit NRF2 function in the cell line panel (PE01, OVCAR3, SKOV3). Activity of the HER-targeted tyrosine kinase inhibitors, erlotinib (ERL) and lapatinib (LAP), was evaluated after NRF2 activation.

Results:

While tBHQ increased the levels of both phosphorylated-NRF2 (pNRF2) and HER4 in PE01, OVCAR3 and SKOV3 cells, bexatorene and NRF2-target siRNA treatment decreased pNRF2 and total HER4 levels. The tBHQ-dependent pharmacological activation of NRF2 attenuated the therapeutic effectiveness of ERL and LAP. Analyses of gene expression data from a HER4 driven reporter system and in vitro or in vivo cancer models, support NRF2 regulation of HER4 expression.

Conclusions:

These results support the presence of signaling interaction between the NRF2 and HER4 receptor pathways and suggest that intervention modulating this cross-talk could have anticancer therapeutic value.

HER2 decreases drug sensitivity of ovarian cancer cells via inducing stem cell-like property in an NFκB-dependent way

Increasing evidence shows that cancer stem cells are responsible for drug resistance and relapse of tumors. In breast cancer, human epidermal growth factor receptor 2 (HER2) induces Herceptin resistance by inducing cancer stem cells. In the present study, we explored the effect of HER2 on cancer stem cells induction and drug sensitivity of ovarian cancer cell lines. First, we found that HER2 overexpression (HER2 OE) induced, while HER2 knockdown (HER2 KD) decreased CD44+/CD24- population. Consistently, HER2 expression was closely correlated with the sphere formation efficiency (SFE) of ovarian cancer cells. Second, we found that NFκB inhibition by specific inhibitor JSH23 or siRNA targetting subunit p65 dramatically impaired the induction of ovarian cancer stem cells by HER2, indicating that NFκB mediated HER2-induced ovarian cancer stem cells. Third, we found that HER2 KD significantly attenuated the tumorigenicity of ovarian cancer cells. Further, we found that HER2 inhibition increased drastically the sensitivity of ovarian cancer cells to doxorubicin (DOX) or paclitaxel (PTX). Finally, we examined the correlation between HER2 status and stem cell-related genes expression in human ovarian tumor tissues, and found that expressions of OCT4, COX2, and Nanog were higher in HER2 positive tumors than in HER2 negative tumors. Consistently, the 5-year tumor-free survival rate of HER2 positive patients was dramatically lower than HER2 negative patients. Taken together, our data indicate that HER2 decreases drug sensitivity of ovarian cancer cells via inducing stem cell-like property.

Phase Ib with expansion study of olaparib plus weekly (Metronomic) carboplatin and paclitaxel in relapsed ovarian cancer patients

OBJECTIVE

Our goals were to: establish the maximum-tolerated dose of olaparib tablets combined with metronomic carboplatin and paclitaxel in patients with relapsed high-grade serous ovarian cancer; evaluate dose-limiting toxicities; and evaluate efficacy at the maximum tolerated dose.

METHODS

In this open-label, single-arm, investigator-initiated trial (ClinicalTrials.gov NCT01650376), patients with high-grade serous ovarian cancer who failed primary platinum and taxane therapy received oral olaparib tablets twice daily days 1-3 each week combined with fixed-dose metronomic carboplatin AUC2 and paclitaxel 60 mg/m² weekly for 3 out of 4 weeks. A 3 × 3 design was used to determine the olaparib maximum tolerated dose. Combination therapy continued until disease progression, but patients with partial or complete response were transitioned to olaparib maintenance therapy. All patients were included in the analysis.

RESULTS

The maximum tolerated dose of olaparib tablets was 150 mg twice daily with metronomic carboplatin and paclitaxel. 54 women were enrolled, 14 in phase Ib and 40 in the expansion phase. The median number of prior therapeutic regimens was 3. Response included 13 complete remission (24%) and 16 partial remission (30%) per Response Evaluation Criteria in Solid Tumors version 1.1 (RECIST 1.1) for an overall response rate of 54% (95% CI 40% to 67%). Of 47 patients who underwent BRCA testing, 23 were BRCA mutation (BRCAm) and 24 B RCA wild type (BRCAwt). Progression-free survival for BRCAm was 12.1 months versus 4.8 for BRCAwt (p=0.0001). Median overall survival for BRCAm was 24.1 months versus 10.4 months for BRCAwt (p=0.02). 42 patients (78%) experienced grade 3-4 toxicities with combination therapy; the most common were hematologic. There were no treatment related deaths. Among 14 patients who received maintenance therapy, 7 experienced grade 1-2 non-hematologic toxicities.

CONCLUSIONS

Olaparib 150 mg tablet twice daily can be safely administered in combination with metronomic carboplatin and paclitaxel in pre-treated relapsed ovarian cancer with 24% complete remission. BRCAm patients had statistically significant longer progression-free survival and overall survival than BRCAwt.

TRIAL REGISTRATION NUMBER

NCT01650376.

Analysis of wntless (WLS) expression in gastric, ovarian, and breast cancers reveals a strong association with HER2 overexpression

The oncogenic role of WNT is well characterized. Wntless (WLS) (also known as GPR177, or Evi), a key modulator of WNT protein secretion, was recently found to be highly overexpressed in malignant astrocytomas. We hypothesized that this molecule may be aberrantly expressed in other cancers known to possess aberrant WNT signaling such as ovarian, gastric, and breast cancers. Immunohistochemical analysis using a TMA platform revealed WLS overexpression in a subset of ovarian, gastric, and breast tumors; this overexpression was associated with poorer clinical outcomes in gastric cancer (P=0.025). In addition, a strong correlation was observed between WLS expression and human epidermal growth factor receptor 2 (HER2) overexpression. Indeed, 100% of HER2-positive intestinal gastric carcinomas, 100% of HER2-positive serous ovarian carcinomas, and 64% of HER2-positive breast carcinomas coexpressed WLS protein. Although HER2 protein expression or gene amplification is an established predictive biomarker for trastuzumab response in breast and gastric cancers, a significant proportion of HER2-positive tumors display resistance to trastuzumab, which may be in part explainable by a possible mechanistic link between WLS and HER2.

Ovarian cancer: opportunity for targeted therapy

Ovarian cancer is a common cause of cancer mortality in women with limited treatment effectiveness in advanced stages. The limitation to treatment is largely the result of high rates of cancer recurrence despite chemotherapy and eventual resistance to existing chemotherapeutic agents. The objective of this paper is to review current concepts of ovarian carcinogenesis. We will review existing hypotheses of tumor origin from ovarian epithelial cells, Fallopian tube, and endometrium. We will also review the molecular pathogenesis of ovarian cancer which results in two specific pathways of carcinogenesis: (1) type I low-grade tumor and (2) type II high-grade tumor. Improved understanding of the molecular basis of ovarian carcinogenesis has opened new opportunities for targeted therapy. This paper will also review these potential therapeutic targets and will explore new agents that are currently being investigated.