A literature review of molecular markers predictive of clinical response to cytotoxic chemotherapy in patients with breast cancer

Obesity-Altered Adipose Stem Cells Promote ER⁺ Breast Cancer Metastasis through Estrogen Independent Pathways

Adipose stem cells (ASCs) play an essential role in tumor microenvironments. These cells are altered by obesity (obASCs) and previous studies have shown that obASCs secrete higher levels of leptin. Increased leptin, which upregulates estrogen receptor alpha (ERα) and aromatase, enhances estrogen bioavailability and signaling in estrogen receptor positive (ER⁺) breast cancer (BC) tumor growth and metastasis. In this study, we evaluate the effect of obASCs on ER⁺BC outside of the ERα signaling axis using breast cancer models with constitutively active ERα resulting from clinically relevant mutations (Y537S and D538G). We found that while obASCs promote tumor growth and proliferation, it occurs mostly through abrogated estrogen signaling when BC has constitutive ER activity. However, obASCs have a similar promotion of metastasis irrespective of ER status, demonstrating that obASC promotion of metastasis may not be completely estrogen dependent. We found that obASCs upregulate two genes in both ER wild type (WT) and ER mutant (MUT) BC: SERPINE1 and ABCB1. This study demonstrates that obASCs promote metastasis in ER WT and MUT xenografts and an ER MUT patient derived xenograft (PDX) model. However, obASCs promote tumor growth only in ER WT xenografts.

Is Bcl-2 a predictive marker of neoadjuvant chemotherapy response in patients with urothelial bladder cancer undergoing radical cystectomy?

Background: Response to neoadjuvant cisplatin treatment in bladder cancer has been linked to expression of Bcl-2 protein by cancer cells. The objective of this study was to test Bcl-2 as a predictive marker of neoadjuvant cisplatin chemotherapy response in a patient cohort from randomized cystectomy trials. Methods: Tumor samples were taken from 247 patients with T2-T4 bladder cancer enrolled in two randomized trials comparing cystectomy with or without neoadjuvant chemotherapy. Tissue microarrays from pre-intervention transurethral resection specimens were assessed for Bcl-2 protein status by immunohistochemistry. Extension of staining above 10% was regarded as positive. Downstaging and survival ratios in relation to Bcl-2 immunoreactivity and neoadjuvant chemotherapy utilization were calculated using the log rank test and multivariate Cox proportional hazards regression analyses. Results: Bcl-2 expression was positive in 38% and negative in 62% of the 236 evaluable patients. Bcl-2 negative patients receiving neoadjuvant chemotherapy had a significant increase in survival (p = 0.009), while Bcl-2 positive patients showed no difference (p = 0.4). However, the interaction variable between neoadjuvant chemotherapy and biomarker status was not significant (p = 0.38). When the prognostic value was assessed in the no-chemotherapy group, 5-year overall survival times were significantly better among Bcl-2 positive patients than among Bcl-2 negative patients (42 months vs 33 months, p = 0.04), but again Bcl-2 status did not remain independent when other factors were adjusted. Also, in a multivariate analysis with all patients, Bcl-2 was not significant. Conclusions: Bcl-2 status is not an independent predictor of neoadjuvant cisplatin chemotherapy response and is not prognostic in muscle-invasive bladder cancer.

Measurement of molecular biomarkers that predict the tumor response in estrogen receptor-positive breast cancers after dose-dense (biweekly) paclitaxel/carboplatin neoadjuvant chemotherapy

The aim of this study was to determine the predictive value of the clinical and histopathological characteristics of estrogen receptor (ER)-positive patients treated with dose-dense paclitaxel/carboplatin neoadjuvant chemotherapy (NCT). Pathological complete response (pCR) and the change in tumor size between pre- and post-NCT were used to evaluate the tumor response.85 ER-positive breast cancer patients who were treated with dose-dense (biweekly) paclitaxel/carboplatin NCT were analyzed with respect to the expression of progesterone receptor (PgR), Tau, Ki67, human epidermal growth factor receptor 2 (HER2), and Bcl-2 by immunohistochemistry (IHC). These data were used to determine whether these biomarkers could predict the tumor response. A univariate analysis showed that the patients who tested positive for HER2 expression (56.00% vs 11.67%, p<0.01), negative for Tau expression (41.94% vs 14.81%, p=0.005), negative for Bcl-2 expression (46.43% vs 14.04%, p<0.01) and had smaller (≤2 cm) tumors (45.00% vs 18.46%, p=0.02) were associated with higher pCR rates. A multivariate analysis showed that a HER2-positive status (OR: 6.244; 95%CI: 1.734-22.487; p=0.005), Bcl-2-negative status (OR: 0.236; 95%CI: 0.064-0.869; p=0.030) and smaller (≤2 cm) tumor sizes (OR: 0.188; 95%CI: 0.046-0.767; p=0.020) are independent predictors of pCRs. The tumor sizes were significantly reduced in patients with HER2-positive, Tau-negative, Bcl-2-negative and high Ki67 index breast cancer. In conclusion, Bcl-2 negative, HER2-positive and smaller (≤2 cm) tumor sizes are independent predictors of pCR in ER-positive patients treated with dose-dense (biweekly) paclitaxel/carboplatin NCT. This study is registered with ClinicalTrials.gov (NCT0205986).

LRIG1 enhances chemosensitivity by modulating BCL-2 expression and receptor tyrosine kinase signaling in glioma cells

PURPOSE

Leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) are an inhibitor of receptor tyrosine kinases (RTKs) that was discovered in recent years, and many studies showed that LRIG1 is a tumor suppressor gene and may be related to tumor drug resistance. In this study, we explored whether LRIG1 protein expression can improve the chemosensitivity of glioma cells and what was its mechanism.

MATERIALS AND METHODS

We collected 93 cases of glioma tissues and detected the expression of LRIG1 and BCL-2. We constructed a multidrug resistance cell line U251/multidrug resistance (MDR) and examined the change of LRIG1 and BCL-2 at mRNA and protein expression levels. LRIG1 expression was upregulated in U251/MDR cells and we detected the change of multidrug resistance. Meanwhile, we changed the expression of LRIG1 and BCL-2 and explored the relationship between LRIG1 and BCL-2. Finally, we also explored the relationship between LRIG1 and RTKs.

RESULTS

LRIG1 was negatively correlated with BCL-2 expression in glioma tissue and U251/MDR cells, and upregulation of LRIG1 can enhance chemosensitivity and inhibit BCL-2 expression. Furthermore, LRIG1 was negatively correlated with RTKs in U251/MDR cells.

CONCLUSION

These results demonstrated that LRIG1 can improve chemosensitivity by modulating BCL-2 expression and RTK signaling in glioma cells.

Design, synthesis, and biological evaluation of (S)-valine thiazole-derived cyclic and noncyclic peptidomimetic oligomers as modulators of human P-glycoprotein (ABCB1)

Multidrug resistance caused by ATP binding cassette transporter P-glycoprotein (P-gp) through extrusion of anticancer drugs from the cells is a major cause of failure in cancer chemotherapy. Previously, selenazole-containing cyclic peptides were reported as P-gp inhibitors and were also used for co-crystallization with mouse P-gp, which has 87 % homology to human P-gp. It has been reported that human P-gp can simultaneously accommodate two to three moderately sized molecules at the drug binding pocket. Our in silico analysis, based on the homology model of human P-gp, spurred our efforts to investigate the optimal size of (S)-valine-derived thiazole units that can be accommodated at the drug binding pocket. Towards this goal, we synthesized varying lengths of linear and cyclic derivatives of (S)-valine-derived thiazole units to investigate the optimal size, lipophilicity, and structural form (linear or cyclic) of valine-derived thiazole peptides that can be accommodated in the P-gp binding pocket and affects its activity, previously an unexplored concept. Among these oligomers, lipophilic linear (13) and cyclic trimer (17) derivatives of QZ59S-SSS were found to be the most and equally potent inhibitors of human P-gp (IC50 =1.5 μM). As the cyclic trimer and linear trimer compounds are equipotent, future studies should focus on noncyclic counterparts of cyclic peptides maintaining linear trimer length. A binding model of the linear trimer 13 within the drug binding site on the homology model of human P-gp represents an opportunity for future optimization, specifically replacing valine and thiazole groups in the noncyclic form.

Radio-sensitization by Piper longumine of human breast adenoma MDA-MB-231 cells in vitro

BACKGROUND

The current study investigated the effects of Piper longumine on radio-sensitization of human breast cancer MDA-MB-231 cells and underlying mechanisms.

MATERIALS AND METHODS

Human breast cancer MDA-MB-231 cells were cultured in vitro and those in logarithmic growth phase were selected for experiments divided into four groups: control, X-ray exposed, Piper longumine, and Piper longumine combined with X-rays. Conogenic assays were performed to determine the radio-sensitizing effects. Cell survival curves were fitted by single-hit multi-target model and then the survival fraction (SF), average lethal dose (D0), quasi-threshold dose (Dq) and sensitive enhancement ratio (SER) were calculated. Cell apoptosis was analyzed by flow cytometry (FCM).Western blot assays were employed for expression of apoptosis-related proteins (Bc1-2 and Bax) after treatment with Piper longumine and/or X-ray radiation. The intracellular reactive oxygen species (ROS) level was detected by FCM with a DCFH-DA probe.

RESULTS

The cloning formation capacity was decreased in the group of piperlongumine plus radiation, which displayed the values of SF2, D0, Dq significantly lower than those of radiation alone group and the sensitive enhancement ratio (SER) of D0 was1.22 and 1.29, respectively. The cell apoptosis rate was increased by the combination treatment of Piper longumine and radiation. Piper longumine increased the radiation-induced intracellular levels of ROS. Compared with the control group and individual group, the combination group demonstrated significantly decreased expression of Bcl-2 with increased Bax.

CONCLUSIONS

Piper longumine at a non-cytotoxic concentration can enhance the radio-sensitivity of MDA- MB-231cells, which may be related to its regulation of apoptosis-related protein expression and the increase of intracellular ROS level, thus increasing radiation-induced apoptosis.

Bcl-2 expression predicts sensitivity to chemotherapy in breast cancer: a systematic review and meta-analysis

Background

Numerous studies have yielded inconclusive results regarding the relationship between anti-apoptotic protein Bcl-2 expression and the sensitivity to chemotherapy in the patients with breast cancer. The purpose of the current study was therefore to elaborate their relationship.

Methods, findings

A total of 23 previously published eligible studies involving 2,467 cases were identified and included in this meta-analysis. Negative Bcl-2 expression was associated with good chemotherapy response in breast cancer patients (total objective response [OR]: risk ratio [RR] = 1.16, 95% confidence interval [CI] = 1.02-1.32, p = 0.026; total complete response [CR]: RR = 1.67, 95% CI = 1.24-2.24, p = 0.001; pathological CR: RR = 1.92, 95% CI = 1.38-2.69, p < 0.001). In further stratified analyses, this association remained for sub-groups of response in neoadjuvant chemotherapy setting, especially pathological CR. Besides, negative Bcl-2 expression was significantly associated with good OR and pathological CR in anthracycline-based chemotherapy subgroup. Furthermore, there were significant links between negative Bcl-2 expression and taxane-based chemotherapy with pathological CR, but not OR.

Conclusion

The results of the present meta-analysis suggest that Bcl-2 expression is a predictive factor for chemotherapy sensitivity in breast cancer patients. They could also potentially benefit further clinical treatment for breast cancers.

Borrelidin has limited anti-cancer effects in bcl-2 overexpressing breast cancer and leukemia cells and reveals toxicity in non-malignant breast epithelial cells

Clinically effective anti-cancer drugs have to tread a narrow line between selective cytotoxicity on tumor cells and tolerable adverse effects against healthy tissues. This causes the failure of many potential cancer drugs in advanced clinical trials, hence signifying the importance of a comprehensive initial estimate of the cytotoxicity of prospective anti-cancer drugs in preclinical studies. In this study, the cytotoxicity of borrelidin, a macrolide antibiotic with a high cytotoxic selectivity for proliferating endothelial cells and leukemia cells, was tested on malignant and non-malignant breast cells. Highly metastatic breast cancer cell lines (MDA-MB-231 and MDA-MB-435) showed promising results and exhibited good sensitivity to borrelidin at low nanomolar concentrations, but borrelidin was cytotoxic to a non-malignant breast epithelial cell line (MCF10A) as well. Furthermore, although a high sensitivity of endothelial cells (human umbilical vein endothelial cells; HUVEC) and individual leukemia cell lines (Jurkat and IM9) to borrelidin was confirmed in this study, another leukemia cell line (HL60) and an immortalized endothelial cell line (EA.hy926) displayed a significantly decreased sensitivity. Reduced sensitivity to borrelidin was associated with elevated bcl-2 expression in these cell lines. In conclusion, the results presented show that borrelidin displays high and selective cytotoxicity against subgroups of cancer cells and endothelial cells, but, owing to its non-specific toxicity to non-malignant cells, its clinical application might be restricted because of likely adverse effects and limited efficacy in bcl2-overexpressing cancer cells.

Tumor P-Glycoprotein Correlates with Efficacy of PF-3758309 in in vitro and in vivo Models of Colorectal Cancer

P-glycoprotein (P-gp), a member of the ATP-binding cassette transporter family, is overexpressed in a number of different cancers and some studies show that P-gp overexpression can be correlated to poor prognosis or therapeutic resistance. Here we sought to elucidate if PF-3758309 (PF-309), a novel p-21 activated kinase inhibitor, efficacy was influenced by tumor P-gp. Based on in vitro proliferation data, a panel of colorectal cancer cell lines were ranked as sensitive or resistant and ABCB1 (P-gp) expression was evaluated by microarray for these cell lines. P-gp expression was determined by western blot and activity determined by rhodamine efflux assay. Knock down of P-gp and pharmacologic inhibition of P-gp to restore PF-309 activity was performed in vitro. PF-309 activity was evaluated in vivo in cell line xenograft models and in primary patient derived tumor xenografts (PDTX). Mice were treated with 25 mg/kg PF-309 orally, twice daily. On the last day of treatment, tumor and plasma were collected for PF-309 analysis. Here we show that ABCB1 gene expression correlates with resistance to PF-309 treatment in vitro and the expression and activity of P-gp was verified in a panel of resistant cells. Furthermore, inhibition of P-gp increased the sensitivity of resistant cells, resulting in a 4–100-fold decrease in the IC50s. Eleven cell line xenografts and 12 PDTX models were treated with PF-309. From the cell line xenografts, we found a significant correlation between ABCB1 gene expression profiles and tumor response. We evaluated tumor and plasma concentrations for eight tumor models (three cell line xenografts and five PDTX models) and a significant correlation was found between tumor concentration and response. Additionally, we show that tumor concentration is approximately fourfold lower in tumors that express P-gp, verified by western blot. Our in vitro and in vivo data strongly suggests that PF-309 efficacy is influenced by the expression of tumor P-gp.

Paclitaxel attenuates Bcl-2 resistance to apoptosis in breast cancer cells through an endoplasmic reticulum-mediated calcium release in a dosage dependent manner

To address the controversy regarding efficacy of paclitaxel in the presence of the anti-apoptotic protein Bcl-2, we investigated calcium stored in the endoplasmic reticulum as a potential factor. Our results showed that the ER calcium store is a common target for both paclitaxel and Bcl-2 protein. Paclitaxel directly associates with the endoplasmic reticulum to stimulate the release of calcium into the cytosol, contributing to the induction of apoptosis. However, Bcl-2 expression suppresses the cell's pro-apoptotic response of endoplasmic reticulum calcium release, thus inhibiting susceptibility of cancer cells to undergo apoptosis. Depending upon dosage, a paclitaxel-induced stimulatory effect can overcome the Bcl-2-mediated inhibitory effect on endoplasmic reticulum calcium release, thus attenuating the resistance of Bcl-2 to apoptosis. Our finding is the first to demonstrate that endoplasmic reticulum calcium plays a key role in the efficacy of paclitaxel in the presence of Bcl-2, thus providing insight into the complex but crucial paclitaxel-calcium-Bcl-2 relationship, which may impact breast cancer treatment.

Characterisation of tumour-infiltrating macrophages: impact on response and survival in patients receiving primary chemotherapy for breast cancer

The role of the tumour microenvironment and complex cellular interactions has attracted interest in responses to primary chemotherapy. Of particular interest are tumour-infiltrating T cells and tumour-infiltrating macrophages (TIMs). We evaluated TIMs and their key activation markers in patients with breast cancer undergoing primary chemotherapy related to response and survival. One hundred and ninety nine patients with large or locally advanced breast cancers received primary chemotherapy. Clinical data, histopathological responses to chemotherapy and survival were examined related to infiltrating cells in tumour microenvironments: cluster of differentiation (CD)3 (pan T cell); CD4 (helper T cells); CD8 (cytotoxic T cells); CD25 (activated T cells); CD68, suppressor of cytokine signalling (SOCS)1, SOCS3 (macrophages); and CD11c and CD205 (dendritic). In tumours demonstrating better responses to chemotherapy, there were significantly fewer CD4(+) T-helper cells than a poorer response (p < 0.05). There were increased numbers of SOCS3 expressing macrophages (pro-inflammatory) in tumours with complete pathological responses compared with no response to chemotherapy (p < 0.05). There was no association between SOCS1 expressing macrophages (anti-inflammatory) and tumour response. Multivariate analysis revealed that factors indicating better survival were receiving anthracycline plus docetaxel (ExpB = 1.166; p = 0.006), better pathological chemotherapy response (ExpB = 0.309; p = 0.009) and a low macrophage SOCS1 expression (ExpB = 13.465; p = 0.044). This study highlights the heterogeneity of TIMs and provides further insight into complex interactions within tumours. The results emphasise the importance of characterising activation status of infiltrating macrophages and provides proof of principle for using macrophage SOCS protein expression as a survival predictor. The apparent impact of macrophage subsets on overall survival underlines the therapeutic potential of manipulating macrophage activation in cancer.

Metastatic soft tissue sarcoma chemotherapy: an opportunity for personalized medicine

BACKGROUND

Soft tissue sarcoma (STS) includes biologically and histologically diverse mesenchymal tumors that are relatively chemotherapy-resistant compared with other sarcoma subtypes.

METHODS

The authors discuss the clinical challenges frequently encountered by medical oncologists and review the literature for predictive strategies to systematically approach chemotherapy decision making.

RESULTS

There are no clinically validated predictive tests for chemotherapeutic response or resistance in STS. Clinical features including histology, stage, and patient age are currently used to guide therapy decisions in STS.

CONCLUSIONS

A method to predict response or resistance to chemotherapy, utilizing both targeted and conventional agents, would be beneficial in reducing toxicity and improving response rates for patients with STS and also in designing clinical trials for this disease.

Sensitization of BCL-2-expressing breast tumors to chemotherapy by the BH3 mimetic ABT-737

Overexpression of the prosurvival protein BCL-2 is common in breast cancer. Here we have explored its role as a potential therapeutic target in this disease. BCL-2, its anti-apoptotic relatives MCL-1 and BCL-XL, and the proapoptotic BH3-only ligand BIM were found to be coexpressed at relatively high levels in a substantial proportion of heterogeneous breast tumors, including clinically aggressive basal-like cancers. To determine whether the BH3 mimetic ABT-737 that neutralizes BCL-2, BCL-XL, and BCL-W had potential efficacy in targeting BCL-2-expressing basal-like triple-negative tumors, we generated a panel of primary breast tumor xenografts in immunocompromised mice and treated recipients with either ABT-737, docetaxel, or a combination. Tumor response and overall survival were significantly improved by combination therapy, but only for tumor xenografts that expressed elevated levels of BCL-2. Treatment with ABT-737 alone was ineffective, suggesting that ABT-737 sensitizes the tumor cells to docetaxel. Combination therapy was accompanied by a marked increase in apoptosis and dissociation of BIM from BCL-2. Notably, BH3 mimetics also appeared effective in BCL-2-expressing xenograft lines that harbored p53 mutations. Our findings provide in vivo evidence that BH3 mimetics can be used to sensitize primary breast tumors to chemotherapy and further suggest that elevated BCL-2 expression constitutes a predictive response marker in breast cancer.

Novel second generation analogs of eribulin. Part I: Compounds containing a lipophilic C32 side chain overcome P-glycoprotein susceptibility

Eribulin mesylate (Halaven™), a totally synthetic analog of the marine polyether macrolide halichondrin B, has recently been approved in the United States as a treatment for breast cancer. It is also currently under regulatory review in Japan and the European Union. Our continuing medicinal chemistry efforts on this scaffold have focused on oral bioavailability, brain penetration and efficacy against multidrug resistant (MDR) tumors by lowering the susceptibility of these compounds to P-glycoprotein (P-gp)-mediated drug efflux. Replacement of the 1,2-amino alcohol C32 side chain of eribulin with fragments neutral at physiologic pH led to the identification of analogs with significantly lower P-gp susceptibility. The analogs maintained low- to sub-nM potency in vitro against both sensitive and MDR cell lines. Within this series, increasing lipophilicity generally led to decreased P-gp susceptibility. In addition to potency in cell culture, these compounds showed in vivo activity in mouse xenograft models.

[Triple-negative breast carcinoma--rewiev of current literature]

Breast cancer is one of the most common malignancies in women. Approximately 15% of cases belong to the triple-negative breast cancer (TNBC) group, in which no estrogen/progesterone receptors, or HER2 expression is detected. The unfavorable prognosis of this group of patients, as well as the lack of effective targeted therapy makes TNBC the subject of intensive research. In the present study, we searched PubMed for publications from January 2007 to June 2009 with the following key-words in addition to "breast cancer" and "triple negative": "epidemiology" or "gene-profile" or "predictive" or "prognostic" or "therapy" or "review". A total of 513 publications were identified. Relevant references were also reviewed. Beyond the well-known facts that TNBC affects younger patients, and is more common among Afro- or Hispano-Americans with lower socioeconomic status, hormonal environment and obesity emerged as potential etiologic factors. TNBC is not a homogenous disease. It can be further sub-classified based on histomorphologic features and immunohistochemistry. Hereditary BRCA1 mutations as well as acquired BRCA1 disfunction are described to be common in TNBC. Previously, many investigators considered TNBC to be identical to a subgroup called basal-like breast cancer defined by gene expression micro-array technology, but in the light of more recent findings, this view is no longer accepted by most investigators. Several large studies provide evidence that triple negativity, per se, is an independent adverse prognostic factor, in spite of the fact that approximately 10% of TNBC patients have a good prognosis. The therapy of choice for TNBC is systemic chemotherapy. Promising novel targeted chemotherapeutic agents include PARP1 inhibitors, a new group of compounds exploiting the defective DNA repair machinery. Rubovszky G, Udvarhelyi N, Horváth Z, Láng I, Kásler M. Triple negative breast carcinoma - rewiev of current literature.

Perspectives and potential applications of nanomedicine in breast and prostate cancer

Nanomedicine is a branch of nanotechnology that includes the development of nanostructures and nanoanalytical systems for various medical applications. Among these applications, utilization of nanotechnology in oncology has captivated the attention of many research endeavors in recent years. The rapid development of nano-oncology raises new possibilities in cancer diagnosis and treatment. It also holds great promise for realization of point-of-care, theranostics, and personalized medicine. In this article, we review advances in nano-oncology, with an emphasis on breast and prostate cancer because these organs are amenable to the translation of nanomedicine from small animals to humans. As new drugs are developed, the incorporation of nanotechnology approaches into medicinal research becomes critical. Diverse aspects of nano-oncology are discussed, including nanocarriers, targeting strategies, nanodevices, as well as nanomedical diagnostics, therapeutics, and safety. The review concludes by identifying some limitations and future perspectives of nano-oncology in breast and prostate cancer management.

Super-SILAC mix for quantitative proteomics of human tumor tissue

We describe a method to accurately quantify human tumor proteomes by combining a mixture of five stable-isotope labeling by amino acids in cell culture (SILAC)-labeled cell lines with human carcinoma tissue. This generated hundreds of thousands of isotopically labeled peptides in appropriate amounts to serve as internal standards for mass spectrometry-based analysis. By decoupling the labeling from the measurement, this super-SILAC method broadens the scope of SILAC-based proteomics.