Genetic Variants in Oxidative Stress–Related Genes Predict Chemoresistance in Primary Breast Cancer: A Prospective Observational Study and Validation

Polymorphisms and Pharmacogenomics of NQO2: The Past and the Future

The flavoenzyme N-ribosyldihydronicotinamide (NRH):quinone oxidoreductase 2 (NQO2) catalyzes two-electron reductions of quinones. NQO2 contributes to the metabolism of biogenic and xenobiotic quinones, including a wide range of antitumor drugs, with both toxifying and detoxifying functions. Moreover, NQO2 activity can be inhibited by several compounds, including drugs and phytochemicals such as flavonoids. NQO2 may play important roles that go beyond quinone metabolism and include the regulation of oxidative stress, inflammation, and autophagy, with implications in carcinogenesis and neurodegeneration. NQO2 is a highly polymorphic gene with several allelic variants, including insertions (I), deletions (D) and single-nucleotide (SNP) polymorphisms located mainly in the promoter, but also in other regulatory regions and exons. This is the first systematic review of the literature reporting on NQO2 gene variants as risk factors in degenerative diseases or drug adverse effects. In particular, hypomorphic 29 bp I alleles have been linked to breast and other solid cancer susceptibility as well as to interindividual variability in response to chemotherapy. On the other hand, hypermorphic polymorphisms were associated with Parkinson's and Alzheimer's disease. The I and D promoter variants and other NQO2 polymorphisms may impact cognitive decline, alcoholism and toxicity of several nervous system drugs. Future studies are required to fill several gaps in NQO2 research.

Molecular mechanisms of ROS-modulated cancer chemoresistance and therapeutic strategies

Drug resistance is the main obstacle to achieving a cure in many cancer patients. Reactive oxygen species (ROS) are master regulators of cancer development that act through complex mechanisms. Remarkably, ROS levels and antioxidant content are typically higher in drug-resistant cancer cells than in non-resistant and normal cells, and have been shown to play a central role in modulating drug resistance. Therefore, determining the underlying functions of ROS in the modulation of drug resistance will contribute to develop therapies that sensitize cancer resistant cells by leveraging ROS modulation. In this review, we summarize the notable literature on the sources and regulation of ROS production and highlight the complex roles of ROS in cancer chemoresistance, encompassing transcription factor-mediated chemoresistance, maintenance of cancer stem cells, and their impact on the tumor microenvironment. We also discuss the potential of ROS-targeted therapies in overcoming tumor therapeutic resistance.

Cell surface GRP78: a potential mechanism of therapeutic resistant tumors

GRP78 is a protein that acts as a chaperone within the endoplasmic reticulum (ER) and has multiple functions. It is induced by stress and abets cells from survival. Despite, multiple Stress conditions like ER, chronic psychological and nutritional stress, hypoxia, chemotherapy, radiation therapy, and drug resistance induce cell surface GRP78 (CS-GRP78) expression in cancer cells. Further, CS-GRP78 is associated with increased malignancy and resistance to anti-cancer therapies and is considered a high-value druggable target. Recent preclinical research suggests that targeting CS-GRP78 with anti-GRP78 monoclonal antibodies (Mab) in combination with other agents may be effective in reversing the failure of chemotherapy, radiotherapy, or targeted therapies and increasing the efficacy of solid tumors treatment. This article will review recent evidence on the role of CS-GRP78 in developing resistance to anti-cancer treatments and the potential benefits of combining anti-GRP78 Mab with other cancer therapies for specific patient populations. Furthermore, our limited understanding of how CS-GRP78 regulated in human studies is a major drawback for designing effective CS-GRP78-targeted therapies. Hence, more research is still warranted to translate these potential therapies into clinical applications.

Single nucleotide polymorphisms as the efficient prognostic markers in breast cancer

BACKGROUND

Breast cancer (BC) is known as the most common malignancy in women. Environmental and genetic factors are associated with BC progression. Genetic polymorphisms have been reported as important risk factors of BC prognosis and drug response. Main body: Therefore, in the present review, we have summarized all single nucleotide polymorphisms (SNPs) which have been significantly associated with drug response in BC patients around the world. We have also categorized the reported SNPs based on their related genes functions to clarify the molecular biology of drug responses in BC.

CONCLUSION

The majority of SNPs were reported in detoxifying enzymes, which introduced such genes as the main genetic risk factors during BC drug responses. This review paves the way for introducing a prognostic panel of SNPs for the BC patients in the world.

Control of Oxidative Stress in Cancer Chemoresistance: Spotlight on Nrf2 Role

Chemoresistance represents the main obstacle to cancer treatment with both conventional and targeted therapy. Beyond specific molecular alterations, which can lead to targeted therapy, metabolic remodeling, including the control of redox status, plays an important role in cancer cell survival following therapy. Although cancer cells generally have a high basal reactive oxygen species (ROS) level, which makes them more susceptible than normal cells to a further increase of ROS, chemoresistant cancer cells become highly adapted to intrinsic or drug-induced oxidative stress by upregulating their antioxidant systems. The antioxidant response is principally mediated by the transcription factor Nrf2, which has been considered the master regulator of antioxidant and cytoprotective genes. Nrf2 expression is often increased in several types of chemoresistant cancer cells, and its expression is mediated by diverse mechanisms. In addition to Nrf2, other transcription factors and transcriptional coactivators can participate to maintain the high antioxidant levels in chemo and radio-resistant cancer cells. The control of expression and function of these molecules has been recently deepened to identify which of these could be used as a new therapeutic target in the treatment of tumors resistant to conventional therapy. In this review, we report the more recent advances in the study of Nrf2 regulation in chemoresistant cancers and the role played by other transcription factors and transcriptional coactivators in the control of antioxidant responses in chemoresistant cancer cells.

Functional genetic variants of CTNNBIP1 predict platinum treatment response of Chinese epithelial ovarian cancer patients

Chemotherapy resistance remains a blockade for successful treatment and longer overall survival of patients with epithelial ovarian cancer (EOC). CTNNBIP1 is an inhibitor of β-catenin that is a chemotherapeutic target for EOC treatment. In the present study, we investigated associations between single nucleotide polymorphisms (SNPs) of CTNNBIP1 and platinum treatment response of Han Chinese EOC patients and subsequently performed functional prediction and validation of the resultant SNPs. We found that CTNNBIP1 rs935072 AT/TT variant genotypes were associated with platinum treatment response in the multivariate logistic regression analysis of EOC patients. Specifically, the CTNNBIP1 rs935072 AT/TT genotypes were associated with a decreased risk of developing chemoresistance ([adjusted odds ratio (OR)] = 0.89, 95% confidence interval (CI) = 0.82-0.97 and P=0.010), compared with the AA genotype. Further experiments showed that the underlying mechanism for the CTNNBIP1 rs935072 A>T change in chemotherapy treatment response resulted from a lower binding affinity of miR-27a-3p, thereby leading to up-regulation of the CTNNBIP1 expression. We further found that overexpression of CTNNBIP1 sensitized ovarian cancer cells to platinum treatment. Thus, the present study provides evidence that functional variants of CTNNBIP1 may regulate the expression of CTNNBIP1, a possible mechanism affecting platinum treatment response of EOC patients.

Variants in oxidative stress-related genes affect the chemosensitivity through Nrf2-mediated signaling pathway in biliary tract cancer

Background

Oxidative stress and their effectors play critical roles in carcinogenesis and chemoresistance. However, the role of oxidative stress-related genes variants in biliary tract cancer (BTC) chemoresistance remains unknown. In this work, we aim to investigate oxidative stress-dependent molecular mechanisms underlying chemoresistance, and find potential biomarkers to predict chemotherapy response for BTC.

Methods

Sixty-six SNPs in 21 oxidative stress-related genes were genotyped and analyzed in 367 BTC patients. Immunoblot, immunohistochemical, immunofluorescent, quantitative PCR, chromatin immunoprecipitation analysis and study of animal xenograft models were performed to discover oxidative stress-related susceptibility genes underlying chemoresistance mechanism of BTC.

Findings

We found that 3 functional polymorphisms (CAT_rs769217, GPX4_rs4807542, and GSR_rs3779647), which were shown to affect their respective gene expression levels, modified the effect of chemotherapy on overall survival (OS). We then demonstrated that knockdown of GPX4, CAT, or GSR induced chemoresistance through elevation of ROS level and activation of Nrf2-ABCG2 pathway in BTC cell lines. Moreover, the association between Nrf2 expression and BTC prognosis is only found in patients who received chemotherapy. Knockdown of Nrf2 enhanced chemosensitivity or even eliminated postoperative recurrence in BTC xenograft mouse models. Importantly, upon chemotherapy treatment patients harboring high oxidative stress-related score received higher survival benefit from adjuvant chemotherapy compared with patients with low oxidative stress-related score.

Interpretation

The result of our study suggests, for the first time, that the oxidative stress-related score calculated by combining variations in CAT, GPX4, and GSR or Nrf2 expression could be used for predicting the chemosensitivity of BTC patients.

Fund

This work was supported by the National Science Foundation of China, Foundation of Shanghai Shen Kang Hospital Development Center, and Shanghai Outstanding Academic Leaders Plan.

Association between polymorphisms in estrogen metabolism genes and breast cancer development in Chinese women: A prospective case-control study

We comprehensively identified polymorphisms in estrogen-metabolizing genes that may be associated with breast cancer initiation in Chinese women, via an ongoing prospective case-control study.An ongoing prospective case-control study of 427 female case patients diagnosed with breast cancer from August 2013 to March 2015 and 536 women (case controls) with no prior history of cancer or benign breast tumors was performed. Buccal cell specimens were obtained using the cotton swabbing method. DNA was extracted from the buccal cells using the phenol/chloroform method. Genotype was carried out for 5 single nucleotide polymorphisms (rs4646903, rs1056836, rs1695, rs4970737, and rs4680) using direct sequencing.The polymorphic genotypes of glutathione S-transferase (GSTP1) (P = .044) and catechol-O-methyltransferase (COMT) (P = .008) showed significantly different distributions, while that of cytochrome P450 (CYP1B1) (P = .051) showed a slight difference in distribution between healthy women and patients with breast cancer. Individuals with homozygous variant genotypes for GSTP1 or COMT exhibited a higher risk of developing breast cancer than those with wild-type genotypes; however, for CYP1B1, the homozygous variant genotype was associated with a lower risk, and the heterozygous genotype for these 3 genes was not associated with breast cancer development.An individual's risk of breast cancer is only influenced by the specific combination of risk-associated alleles of COMT and GSTP1, despite the protective effects of the homozygous CYP1B1 genotype revealed by univariate analysis.

Interaction between glutathione S-transferase M1-null/present polymorphism and adjuvant chemotherapy influences the survival of breast cancer

Glutathione S‐transferase M (GSTM) family is concerned with oxidative stress, which is associated with breast carcinogenesis and chemotherapy response. The null polymorphism of GSTM1 gene results in a thorough absence of the enzyme function. Our study was to evaluate the association between GSTM1 null/present polymorphism and chemotherapy treatment outcome in breast cancer patients. A total of unrelated 714 patients with a histologically confirmed breast cancer were randomly selected from two independent cancer centers. Polymerase chain reaction was performed to analyze null/present genotypes of GSTM1 in our study. Our study found that the present genotype of GSTM1 was associated with a better relapse‐free survival (RFS) (P = .03) with adjusted hazard ratio (HR) [95% confidence interval (CI)] of 0.63 (95% CI: 0.42‐0.93). The present genotype of GSTM1 was significantly correlated with a better RFS compared with the null genotype in the nonchemotherapy group (HR = 0.17, 95% CI: 0.06‐0.50; P = 0.001), but no effect was observed in the chemotherapy group (HR = 0.81, 95% CI: 0.52‐1.26; P = 0.35). Moreover, the interaction between the GSTM1‐null/present genotype and adjuvant chemotherapy was significant (P = 0.04) in further analysis. Our study suggests that the GSTM1 polymorphism plays a complex role in influencing the chemotherapy response and breast cancer survival. It is suggested that the GSTM1‐present genotype might prevent progression in breast cancer patients. In the meanwhile, it could damage the benefit of adjuvant chemotherapy as well in certain ways.

Genetic Variants Associated with Clinicopathological Profiles in Sporadic Breast Cancer in Sri Lankan Women

PURPOSE

Several single nucleotide polymorphisms (SNPs) have been reported to be associated with clinicopathological profiles in sporadic breast cancer based on studies conducted on major population groups. The knowledge of the effects of these common genetic variants in South Asian populations remains limited. The present study aimed to investigate the association between a selected set of SNPs and the clinicopathological profiles in sporadic breast cancer in Sri Lankan women.

METHODS

A total of 350 postmenopausal women with histologically confirmed invasive breast cancer were genotyped for 58 SNPs located in 36 breast cancer related genes. The clinicopathological factors that were investigated included age of onset, tumor histologic grade, and lymph node involvement, as well as estrogen receptor (ER), progesterone receptor, and human epidermal growth factor receptor 2 (HER2) status. Association testing was performed using logistic regression models adjusted for confounding factors.

RESULTS

Seven SNPs showed significant associations with clinicopathological profiles in breast cancer. The G allele of BRCA1:rs799917 (p=0.047; β [standard error; SE]=-1.069 [0.537]) and the G allele of NQO2:rs17136117 (p=0.040, β [SE]=1.901 [0.923]) were found to be associated with age of onset between 50 and 59 years. The C allele of CDH1:rs13689 (odds ratio [OR], 2.121; p=0.033) was found to be associated with ER-positive breast cancer. The A allele of AKT1:rs1130214 (OR, 2.095; p=0.011) and the C allele of NQO2:rs2071002 (OR, 1.632; p=0.045) were associated with HER2-positive breast cancer. The C allele of BRCA2:rs15869 (OR, 1.600; p=0.041) and the C allele of CCND1:rs7177 (OR, 1.555; p=0.041) were associated with high tumor histologic grade.

CONCLUSION

The common genetic variants identified in the AKT1, BRCA1, BRCA2, CCND1, CDH1, and NQO2 genes could serve as potential clinical and prognostic biomarkers in sporadic breast cancer patients. Further studies are required to validate our current findings in other populations.

The ontogeny and population variability of human hepatic dihydronicotinamide riboside:quinone oxidoreductase (NQO2)

Dihydronicotinamide riboside:quinone oxidoreductase (NQO2) is an enzyme that performs reduction reactions involved in antioxidant defense. We hypothesized that NQO2 hepatic drug clearance would develop in children over time, similar to NQO1. Using human liver cytosol (n = 117), the effects of age, sex, ethnicity, and weight on NQO2 expression and activity were probed. No significant correlations were observed. Biochemical activity of NQO2 was as high at birth as in adults (0.23 ± 0.04 nmol/min/mg protein, mean ± SEM, range 0-1.83). In contrast, modeled hepatic clearance through the NQO2 pathway was up to 10% of adult levels at birth, reaching predicted adult levels (0.3 ± 0.03 L/h) at 14 years of age. Comparisons between NQO1 and NQO2 in the same livers showed that neither protein (P = 0.32) nor activity (P = 0.23) correlated, confirming both orthologs are independently regulated. Because hepatic clearance through NQO2 does not mature until teenage years, compounds detoxified by this enzyme may be more deleterious in children.

GSTT1 and GSTM1 polymorphisms predict treatment outcome for breast cancer: a systematic review and meta-analysis

Observational studies have reported controversial results on the association between GSTT1 and GSTM1 genotypes and treatment outcome of breast cancer. The purpose of this study is to evaluate the association between GSTT1 and GSTM1 and treatment outcome in breast cancer patients. Eligible studies were searched in PubMed, EMBASE, Cochrane Library, and China National Knowledge Infrastructure databases. A random-effect model or fixed-effect model was used to calculate the overall combined risk estimates. Twenty-one studies with a total of 4990 patients were included in this meta-analysis. The GSTM1 null genotype (odds ratio (OR) = 1.33, 95 % confidence interval (CI) 1.01-1.75, P = 0.046) and GSTT1/GSTM1 double null genotype (OR = 2.22, 95 % CI 1.02-4.84, P = 0.045) were significantly associated with an increased tumor response. A reduced overall survival (hazard ratio (HR) = 0.84, 95 % CI 0.72-0.98, P = 0.024) was observed in GSTM1 null genotype, especially in mixed descent (HR = 0.77, 95 % CI 0.61-0.96, P = 0.018) and large sample size (HR = 0.85, 95 % CI 0.72-0.99, P = 0.033). Evidence of publication bias was observed in GSTM1 genotype rather than in GSTT1 genotype. This meta-analysis suggests that GSTM1 null and GSTT1/GSTM1 double null polymorphisms might be significantly associated with an increased tumor response. However, the GSTM1 null genotype might be significantly associated with a reduced overall survival. Future studies are warranted to confirm these findings.

A recessive variant of XRCC4 predisposes to non- BRCA1/2 breast cancer in chinese women and impairs the DNA damage response via dysregulated nuclear localization

XRCC4 plays a crucial role in the non-homologous end joining pathway that maintains genome stability. In this two-stage case-control study with 1,764 non-BRCA1/2 breast cancer patients and 1,623 cancer-free controls, we investigated the contribution of genetic variants of XRCC4 to breast cancer susceptibility in Chinese women. We identified a recessive missense variant, rs3734091 (c.739G>T, p.Ala247Ser), of XRCC4 that was significantly associated with an increased risk of breast cancer (odds ratio [OR] = 3.92, P = 0.007), particularly with the risk of developing triple-negative breast cancer (OR = 18.65, P < 0.0001). This p.Ala247Ser variant disturbed the nuclear localization of XRCC4 in cells homozygous for the rs3734091-T allele but not in heterozygous cells at both the cellular and tissue levels. In heterozygous cells, wild-type XRCC4 facilitated the nuclear localization of the XRCC4^A247S mutant, thus compensating for the impaired localization of XRCC4^A247S. This provided a biological mechanism by which rs3734091 conferred an increased susceptibility to non-BRCA1/2 breast cancer exclusively under a recessive model. Further functional analyses revealed that p.Ala247Ser impaired the DNA damage repair capacity and ultimately perturbed genomic stability. Taken together, our findings document the role of XRCC4 in non-BRCA1/2 breast cancer predisposition and reveal its underlying biological mechanism of action.

Cell surface GRP78: A potential marker of good prognosis and response to chemotherapy in breast cancer

The 78-kDa glucose-regulated protein (GRP78) is a stress induced heat shock protein which, under limiting conditions, functions as a cell surface signaling receptor. Tumor cells are considered to be subjected to a physiologically stressful microenvironment due to their excessive growth. The role of GRP78 in tumor survival has been of notable interest. The present study aimed to assess the potential prognostic and predictive value of cell surface GRP78 expression in breast cancer tumor cells. Cell surface and cytoplasmic expression of GRP78 was examined by immunohistochemical staining of GRP78 in breast cancer archival paraffin-embedded tumor specimens. The cohort studied included breast cancer patients with operable T1,2, estrogen receptor-positive, node-negative cancer who were assessed using the Oncotype DX gene profile, as well as patients with locally advanced disease prior to and following neoadjuvant systemic treatment. GRP78 values were compared between the 2 groups, and prior to and following systemic treatment. Association analyses between GRP78 expression and prognostic markers were also performed. Cox regression analysis was used to examine the impact of these variables on disease-free survival (DFS). No differences in cytoplasmic GRP78 expression were observed. By contrast, the rates of cell surface GRP78 expression were 74.1% in the early stage operable patients, 36% in neoadjuvant systemic treatment patients prior to treatment and 62.5% in patients following systemic treatment (P<0.039). Positive cell surface GRP78 expression was associated with increased expression of the progesterone receptor (P=0.024), p53 expression (P=0.022) and improved DFS (P=0.047). In the case of GRP78 positivity, a trend for a superior response to chemotherapy was observed (P=0.19). The results of the present study indicated that cell surface GRP78 may be used as a marker for good prognosis in breast cancer and a potential marker for response to chemotherapy.

Host genotype and tumor phenotype of chemokine decoy receptors integrally affect breast cancer relapse

PURPOSE

Chemokines may play vital roles in breast cancer progression and metastasis. The primary members of chemokine decoy receptors (CDR), DARC and D6, are expressed in breast tumors and lymphatic/hematogenous vessels. CDRs sequestrate the pro-malignant chemokines. We hypothesized that breast cancer patients carrying different levels of CDR expression in tumor and/or in host might have differing clinical outcomes.

METHODS

This prospective observational study measured both expression and germline genotype of DARC and D6 in 463 primary breast cancer patients enrolled between 2004 and 2006. The endpoint was breast cancer relapse-free survival (RFS).

RESULTS

There was a significant association between the co-expression of CDR (immunohistochemical expression of both DARC and D6) with RFS (hazard ratio [HR] of 0.32, 95% confidence interval [CI] 0.19 to 0.54). Furthermore, the co-genotype of two non-synonymous polymorphisms (with two major alleles of DARC-rs12075 and D6-rs2228468 versus the others) significantly related to relapse. Mechanistically, the variant-alleles of these two polymorphisms significantly decreased by 20-30% of CCL2/CCL5 (CDR ligands) levels relative to their major counterparts. Multivariate analysis highlighted that the co-expression and co-genotype of CDR were independent predictors of RFS, with HR of 0.46 (95% CI 0.27 to 0.80) and 0.56 (95% CI 0.37 to 0.85), respectively. The addition of host CDR genetic information to tumor-based factors (including co-expression of CDR) improved the relapse prediction ability (P = 0.02 of AUC comparison).

CONCLUSION

The host genotype and tumor phenotype of CDR integrally affect breast cancer relapse. Host-related factors should be considered for individualized prediction of prognosis.

Prognostic information of a previously diagnosed sister is an independent prognosticator for a newly diagnosed sister with breast cancer

BACKGROUND

Breast cancer survival has been shown to be associated among relatives. In this study, we used a population-based cohort of Swedish sisters, both diagnosed with breast cancer, to determine whether prognostic information of a previously diagnosed sibling is useful for the clinical management of a newly diagnosed sibling.

PATIENTS AND METHODS

The population-based cohort included all sister pairs, 1617 sisters, diagnosed with breast cancer in Sweden, from 1 January 1992, through 31 December 2006, with complete follow-up. All information was collected manually from original pathology reports and patient records. The Kappa statistic was used to measure the agreement of primary tumor characteristics between the sisters. We modeled the breast cancer-specific survival using multivariate (Cox) proportional hazard analyses in two steps categorizing the older sister's survival.

RESULTS

Estrogen receptor status was the only tumor characteristic significantly associated between the sisters [κ 0.18 (95% confidence interval (CI) 0.089-0.27)]. Younger sisters with poor older sister survival showed significantly worse survival compared with patients with good older sister survival (log rank, P = 0.017). A twofold increased hazard ratio (HR) for death from breast cancer was found in younger sisters with poor older sister survival compared with patients with good sister survival [HR 2.56 (95% CI 1.16-5.65)], adjusting for age and calendar period of diagnosis, socioeconomic factors, number of children and hospital of primary tumor diagnosis. When further adjusting for primary tumor characteristics and adjuvant therapy, the risk for death from breast cancer in younger sisters with poor older sister survival became more pronounced [HR 3.35 (1.34-8.34)].

CONCLUSIONS

Our findings derived from a population-based cohort of Swedish sister pairs suggest that breast cancer-specific survival is inherited independent of tumor characteristics and treatment in the sibling later diagnosed with the disease. Prognostic information of a previously diagnosed sibling with breast cancer could be important in the clinical management.

Enriched variations in TEKT4 and breast cancer resistance to paclitaxel

Among chemotherapeutic agents, paclitaxel has shown great efficacy against breast cancer. Prediction of paclitaxel response may improve patient outcomes. Here we show, using exome sequencing, that in comparison with pre-treatment biopsies, two TEKT4 germline variations are enriched in post-treatment tumours. We find TEKT4 variations in ~ 10% of an independent cohort of 84 pairs of samples. Tektin4 (encoded by TEKT4) associates closely with tubulin in doublet microtubules and helps stabilize these structures. These two TEKT4 germline variations in a high cis linkage are biologically relevant, as the ectopic expression of variant TEKT4 deregulates the microtubule stability, antagonizes the paclitaxel-induced stabilizing effect of microtubules and increases paclitaxel resistance. Furthermore, TEKT4 germline variations are associated with reduced disease-free survival and overall survival compared with wild-type TEKT4 in patients undergoing paclitaxel-based chemotherapy. Taken together, we reveal a potential mechanism of resistance to paclitaxel through the acquisition of germline variations in breast cancer.

The endoplasmic reticulum stress markers GRP78 and CHOP predict disease-free survival and responsiveness to chemotherapy in breast cancer

Glucose-regulated protein (GRP) 78 and C/-EBP homologous protein (CHOP) are commonly used as markers of endoplasmic reticulum (ER) stress. As an ER chaperone, GRP78 functions as a potent anti-apoptotic factor and confers drug resistance, whereas CHOP is a key initiating factor of ER stress-related cell death. We aimed at investigating the predictive values of GRP78 and CHOP in breast cancer patients who underwent adjuvant chemotherapy. An immunohistochemistry screen for GRP78 and CHOP was performed using a tissue microarray containing 250 tumors from female patients diagnosed with invasive ductal breast carcinoma at the Fudan University Shanghai Cancer Center. The staining results were scored semi-quantitatively, and a prediction model was constructed to verify the hypothesis. In this retrospective cohort study, CHOP correlated with prolonged disease-free survival (HR = 0.385, 95 % CI 0.215-0.688; P = 0.001), whereas GRP78 showed an opposite association (HR = 4.573; 95 % CI 2.291-9.128; P < 0.001). Moreover, in a GRP78-positive subset, CHOP overexpression correlated with a lower risk of recurrence. In the receiver operating characteristic analysis, the prediction capability of the predictive model combining the above two markers surpassed that of the traditional model (P = 0.0085 for the area under the curve comparison). Within the anthracycline-treatment subgroup, the combined GRP78 and CHOP exhibited similar predictive significance. Cumulatively, our findings suggest a tight association between ER stress markers and clinical outcomes for patients with breast cancer.

GATA3 mutations define a unique subtype of luminal-like breast cancer with improved survival

BACKGROUND

The GATA3 gene (GATA-binding protein 3) is one of the most frequently mutated genes in breast cancer. The objective of the current study was to determine the clinicopathologic characteristics of patients with breast cancer harboring GATA3 mutations.

METHODS

The authors examined the somatic mutation status of GATA3 and performed survival analysis in The Cancer Genome Atlas (TCGA) cohort (n=934) and the Fudan University Shanghai Cancer Center (FUSCC) cohort (n=308). Patient characteristics, including age; menopausal status; tumor laterality; tumor size; lymph node status; tumor grade; molecular subtypes; adjuvant radiotherapy, chemotherapy, and endocrine therapy; and prognosis, together with PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha) and TP53 (tumor protein p53) mutation status, were collected.

RESULTS

GATA3 mutations were detected in 8.8% of patients (82 of 934 patients) in the TCGA cohort and 14.9% of patients (46 of 308 patients) in the FUSCC cohort. GATA3 mutations were found to be significantly associated with luminal-like breast cancer (P=.002 in the TCGA cohort and P<.001 in the FUSCC cohort), and were highly mutually exclusive to PIK3CA mutations (P=.001 in the TCGA cohort and P=.003 in the FUSCC cohort) and TP53 mutations (P<.001 in both cohorts). Furthermore, GATA3 mutations were correlated with improved overall survival in the entire population (P=.025 in the TCGA cohort and P = .043 in the FUSCC cohort) as well as in patients with luminal-like disease who received adjuvant endocrine therapy.

CONCLUSIONS

GATA3 mutations mainly occur in patients with luminal-like breast cancer and have identifiable clinicopathologic and genetic characteristics, highlighting a subgroup of patients with breast cancer in whom limited therapy may be appropriate.

The role of reduced intracellular concentrations of active drugs in the lack of response to anticancer chemotherapy

A major difficulty in the treatment of cancers is the poor response of many tumors to pharmacological regimens. This situation can be accounted for by the existence of a variety of complex mechanisms of chemoresistance (MOCs), leading to reduced intracellular concentrations of active agents, changes in the molecular targets of the drugs, enhanced repair of drug-induced modifications in macromolecules, stimulation of anti-apoptotic mechanisms, and inhibition of pro-apoptotic mechanisms. The present review focuses on alterations in the expression and appearance of the genetic variants that affect the genes involved in reducing the amount of active agents inside tumor cells. These alterations can occur through two mechanisms: either by lowering uptake or enhancing efflux (so-called MOC-1a and MOC-1b, respectively), or by decreasing the activation of prodrugs or enhancing inactivation of active agents through their biotransformation (MOC-2). The development of chemosensitizers that are useful in implementing the pharmacological manipulation of these processes constitutes a challenge to modern pharmacology. Nevertheless, the important physiological roles of the most relevant genes involved in MOC-1a, MOC-1b, and MOC-2 make it difficult to prevent the side effects of chemosensitizers. A more attainable goal in this area of pharmacological enquiry is the identification of proteomic profiles that will permit oncologists to accurately predict a lack of response to a given regimen, which would be useful for adapting treatment to the personal situation of each patient.