αB-crystallin is a useful marker for triple negative and basal breast cancers

The role of heat shock proteins in metastatic colorectal cancer: A review

Heat shock proteins (HSPs) are a large molecular chaperone family classified by their molecular weights, including HSP27, HSP40, HSP60, HSP70, HSP90, and HSP110. HSPs are likely to have antiapoptotic properties and participate actively in various processes such as tumor cell proliferation, invasion, metastases, and death. In this review, we discuss comprehensively the functions of HSPs associated with the progression of colorectal cancer (CRC) and metastasis and resistance to cancer therapy. Taken together, HSPs have numerous clinical applications as biomarkers for cancer diagnosis and prognosis and potential therapeutic targets for CRC and its related metastases.

AlphaB-crystallin and breast cancer: role and possible therapeutic strategies

AlphaB-crystallin (HSPB5) is one of the most prominent and well-studied members of the small heat shock protein (sHsp) family. To date, it is known that this protein modulates significant cellular processes and therefore, it is not surprising that its deregulation is involved in various human pathologies, including cancer diseases. Despite the pathogenic significance of HSPB5 in cancer and its regulatory mechanism related to aggressiveness is poorly understood, several reports describe the association of breast carcinoma progression with HSPB5, whose expression is also considered an independent predictor of breast cancer metastasis to the brain. Indeed, numerous authors indicate HSPB5 as a new valuable biomarker for clinicopathological parameters and poor prognosis in breast cancer. Considering the cytoprotective, anti-apoptotic, pro-angiogenic, and pro-metastatic properties of the sHsps, it is not surprising that they are considered as promising targets for anticancer treatment, even though, at present, a deeper understanding of their mode of action is needed to allow the development of precise therapeutic interventions. Data on the direct inhibition of different sHsps demonstrate promising results in cancer pathologies; however, specific strategies against HSPB5 have not been considered. This review highlights the most relevant findings on HSPB5 and its role in breast cancer, as well as the possible strategies in using HSPB5 inhibition for therapeutic purposes.

Small Heat Shock Proteins in Cancers: Functions and Therapeutic Potential for Cancer Therapy

Small heat shock proteins (sHSPs) are ubiquitous ATP-independent chaperones that play essential roles in response to cellular stresses and protein homeostasis. Investigations of sHSPs reveal that sHSPs are ubiquitously expressed in numerous types of tumors, and their expression is closely associated with cancer progression. sHSPs have been suggested to control a diverse range of cancer functions, including tumorigenesis, cell growth, apoptosis, metastasis, and chemoresistance, as well as regulation of cancer stem cell properties. Recent advances in the field indicate that some sHSPs have been validated as a powerful target in cancer therapy. In this review, we present and highlight current understanding, recent progress, and future challenges of sHSPs in cancer development and therapy.

Progression of the role of CRYAB in signaling pathways and cancers

CRYAB is a member of the small heat shock protein family, first discovered in the lens of the eye, and involved in various diseases, such as eye and heart diseases and even cancers, for example, breast cancer, lung cancer, prostate cancer, and ovarian cancer. In addition, CRYAB proteins are involved in a variety of signaling pathways including apoptosis, inflammation, and oxidative stress. This review summarizes the recent progress concerning the role of CRYAB in signaling pathways and diseases. Therefore, the role of CRYAB in signaling pathways and cancers is urgently needed. This article reviews the regulation of CRYAB in the apoptotic inflammatory signaling pathway and its role in cancers progression and as a key role in anti-cancer therapy targeting CRYAB in an effort to improve outcomes for patients with metastatic disease.

Genomic markers of panitumumab resistance including ERBB2/ HER2 in a phase II study of KRAS wild-type (wt) metastatic colorectal cancer (mCRC)

A prospective study was conducted to identify biomarkers associated with resistance to panitumumab monotherapy in patients with metastatic colorectal cancer (mCRC). Patients with previously treated, codon 12/13 KRAS wt, mCRC were prospectively administered panitumumab 6 mg/kg IV q2weeks. Of 34 panitumumab-treated patients, 11 (32%) had progressive disease at 8 weeks and were classified as non-responders.

A Nanostring nCounter-based assay identified a 5-gene expression signature (ERBB2, MLPH, IRX3, MYRF, and KLK6) associated with panitumumab resistance (P = 0.001). Immunohistochemistry and in situ hybridization determined that the HER2 (ERBB2) protein was overexpressed in 4/11 non-responding and 0/21 responding cases (P = 0.035). Two non-responding tumors had ERBB2 gene amplification only, and one demonstrated both ERBB2 amplification and mutation. A non-codon 12/13 KRAS mutation occurred in one panitumumab-resistant patient and was mutually exclusive with ERBB2/HER2 abnormalities.

This study identifies a 5-gene signature associated with non-response to single agent panitumumab, including a subgroup of non-responders with evidence of aberrant ERBB2/HER2 signaling. KRAS wt tumors resistant to EGFRi may be identified by gene signature analysis, and the HER2 pathway plays an important role in resistance to therapy.

αB-crystallin: Portrait of a malignant chaperone as a cancer therapeutic target

αB-crystallin is a widely expressed member of the small heat shock protein family that protects cells from stress by its dual function as a molecular chaperone to preserve proteostasis and as a cell death antagonist that negatively regulates components of the conserved apoptotic cell death machinery. Deregulated expression of αB-crystallin occurs in a broad array of solid tumors and has been linked to tumor progression and poor clinical outcomes. This review will focus on new insights into the molecular mechanisms by which oncogenes, oxidative stress, matrix detachment and other tumor microenvironmental stressors deregulate αB-crystallin expression. We will also review accumulating evidence pointing to an essential role for αB-crystallin in the multi-step metastatic cascade whereby tumor cells colonize distant organs by circumventing a multitude of barriers to cell migration and survival. Finally, we will evaluate emerging strategies to therapeutically target αB-crystallin and/or interacting proteins to selectively activate apoptosis and/or derail the metastatic cascade in an effort to improve outcomes for patients with metastatic disease.

αB-crystallin Expression in Breast Cancer is Associated with Brain Metastasis

BACKGROUND/OBJECTIVES

The molecular chaperone αB-crystallin is expressed in estrogen receptor, progesterone receptor and human epidermal growth factor receptor-2 "triple-negative" breast carcinomas and promotes brain and lung metastasis. We examined αB-crystallin expression in primary breast carcinomas with metastatic data to evaluate its association with prognosis and site-specific metastases.

METHODS

αB-crystallin gene (CRYAB) expression was examined using publically available global-gene expression data (n=855 breast tumors) with first site of distant metastasis information ("855Met"). αB-crystallin protein expression was determined by immunohistochemistry using the clinically annotated tissue microarray (n=3987 breast tumors) from British Columbia Cancer Agency (BCCA). Kaplan-Meier and multivariable Cox regression analyses were used to evaluate the prognostic value of αB-crystallin. Multivariable logistic regression analysis was used to evaluate risks of αB-crystallin and other markers for site of metastasis.

RESULTS

In the 855Met dataset, αB-crystallin gene (CRYAB) expression was an independent predictor of brain as the first distant site of relapse (HR = 1.2, (95% CI 1.0-1.4), P = 0.021). In the BCCA series, αB-crystallin protein expression was an independent prognostic marker of poor breast cancer specific survival (HR = 1.3, (95% CI 1.1-1.6), P = 0.014). Among patients with metastases, αB-crystallin was the strongest independent predictor of brain metastasis (OR = 2.99 (95% CI 1.83-4.89), P < 0.0001) and the only independent predictor of brain as the first site of distant metastasis (OR = 3.15 (95% CI1.43-6.95), P = 0.005). αB-crystallin was also associated with worse survival (3.0 versus 4.7 months, P = 0.007).

CONCLUSIONS

αB-crystallin is a promising biomarker to identify breast cancer patients at high risk for early relapse in the brain, independent of ER and HER2 status.

alphaB-crystallin is a marker of aggressive breast cancer behavior but does not independently predict for patient outcome: a combined analysis of two randomized studies

BACKGROUND

alphaB-crystallin is a small heat shock protein that has recently been characterized as an oncoprotein correlating with the basal core phenotype and with negative prognostic factors in breast carcinomas. The purpose of this study was to evaluate alphaB-crystallin with respect to clinicopathological parameters and the outcome of patients with operable high-risk breast cancer.

METHODS

A total of 940 tumors were examined, derived from an equal number of patients who had participated in two randomized clinical trials (paclitaxel-containing regimen in 793 cases). Immunohistochemistry for ER, PgR, HER2, Ki67, CK5, CK14, CK17, EGFR, alphaB-crystallin, BRCA1 and p53 was performed. BRCA1 mutation data were available in 89 cases.

RESULTS

alphaβ-crystallin was expressed in 170 cases (18.1%) and more frequently in triple-negative breast carcinomas (TNBC) (45% vs. 14.5% non-TNBC, p < 0.001). alphaB-crystallin protein expression was significantly associated with high Ki67 (Pearson chi-square test, p < 0.001), p53 (p = 0.002) and basal cytokeratin protein expression (p < 0.001), BRCA1 mutations (p = 0.045) and negative ER (p < 0.001) and PgR (p < 0.001). Its overexpression, defined as >30% positive neoplastic cells, was associated with adverse overall survival (Wald's p = 0.046). However, alphaB-crystallin was not an independent prognostic factor upon multivariate analysis. No interaction between taxane-based therapy and aβ-crystallin expression was observed.

CONCLUSIONS

In operable high-risk breast cancer, alphaB-crystallin protein expression is associated with poor prognostic features indicating aggressive tumor behavior, but it does not seem to have an independent impact on patient survival or to interfere with taxane-based therapy.

TRIAL REGISTRATIONS

ACTRN12611000506998 (HE10/97 trial) and ACTRN12609001036202 (HE10/00 trial).

Androgen receptor expression shows distinctive significance in ER positive and negative breast cancers

BACKGROUND

Androgen receptor (AR), a nuclear steroid hormone receptor, is differentially expressed in breast cancer subgroups with distinct clinical implications.

METHODS

To investigate the clinical significance of AR in breast cancers more precisely, the expression of AR in a large cohort of breast cancer was correlated with clinicopathological features, biomarker expression, and patients' survival according to different molecular groupings in this study.

RESULTS

Higher AR expression was found in ER+ (57.8 %) than in ER- (24.7 %) cancers. In the ER+ cancers, AR expression was associated with favorable clinicopathological features, including lower grade (p < .001), lower pT stage (p < .001), and positivity for PR (p < .001). It was an independent prognostic factor for longer disease-free survival, mainly in the HER2+ luminal B cancers (hazard ratio [HR] = 0.251, 95 % CI 0.065-0.972, p = .045). In ER- cancers, AR expression was associated with features distinct from basal-like breast cancer, and such features were found in molecular apocrine (MA) cancers. AR correlated with presence of extensive in situ component (p = .006) and apocrine phenotype (p < .001), HER2 (p = .026), and EGFR (p = .048), but negatively with c-kit (p = .041), CK5/6 (p < .001), CK14 (p = .002), and αB-crystallin (p = .038). However, AR expression was found only in 37.8 % of immunohistochemically defined MA. Of note, AR-MA appeared to have a trend of worse overall survival than AR+MA.

CONCLUSIONS

AR expression was different in ER+ and ER- cancers and had different clinical implications. AR alone may not be a good marker for MA subtype. Its expression in MA may have substantial prognostic implication and as such warrants further validation.

Basal-like breast cancer: update on clinicopathologic, immunohistochemical, and molecular features

CONTEXT

Basal-like breast carcinoma (BLBC) is a distinct molecular subtype of breast carcinoma identified through gene expression profiling studies.

OBJECTIVE

To provide the clinical background, the histologic profile, and the immunohistochemical profile of these tumors and discuss the current knowledge of their molecular signature and their implications on targeted molecular therapy.

DATA SOURCES

Data were obtained from review of the pertinent peer-reviewed literature.

CONCLUSIONS

Basal-like breast carcinomas are aggressive tumors with poor prognosis. Lack of targeted therapy makes their treatment a challenging task. Traditional chemotherapy is still associated with a high risk of relapse and death in a high percentage of patients. Platinum-based chemotherapy has been considered as a candidate for the treatment of BLBCs owing to their BRCA1 phenotype. Approximately 22% of patients treated with single-agent cisplatin show pathologic complete response, which is a comparable rate to that seen with nonplatinum agents. Antiangiogenic agents have been promising, but their currently demonstrated limited response is considered disappointing. Additionally, epidermal growth factor receptor was not shown to be a helpful target for BLBC. A recent study has shown that BLBC appears to be especially sensitive to MEK inhibitors, making it a promising therapeutic possibility. The list of new targets is still evolving and the "magic" therapeutic target is yet to be discovered.

αB-crystallin expression is correlated with phospho-ERK1/2 expression in human breast cancer

αB-crystallin is regarded as a biomarker for triple-negative and/or basal-like breast cancer. In normal breast cells, overexpression of αB-crystallin leads to neoplastic-like changes, which likely relate to enhanced expression of phosphorylated ERK1/2 (pERK1/2). In this study, we investigated whether αB-crystallin expression is correlated to pERK1/2 expression in breast cancer. In a balanced tissue microarray the expression of αB-crystallin and pERK1/2 kinase were determined immunohistochemically, together with the triple-negativity and basal-like markers CK5/6 and SMA and the signaling molecules pAKT, pmTOR, EGFR, and IGF-1R. αB-crystallin expression significantly correlated with triple negativity and basal-like markers CK5/6 and SMA (Pearson Chi-square test p=0.004, p=0.001, and p&lt;0.001, respectively). A significant correlation was also observed with pERK1/2 expression (p=0.002). siRNA-mediated knockdown of αB-crystallin in the triple-negative breast cell line MDA-MB468 did not show an effect on pERK1/2 expression levels, indicating that lowering the level of αB-crystallin does not reduce pERK1/2 expression. Our results confirm that αB-crystallin can be used as a biomarker for triple-negative and/or basal-like breast cancer. The expression of αB-crystallin correlates with pERK1/2 expression in breast cancer tissue suggesting that therapies targeting αB-crystallin might be considered for treatment of triple-negative or basal-like breast cancer.

Increased SOX2 expression in less differentiated breast carcinomas and their lymph node metastases

AIMS

SOX2 is a key regulatory gene in embryonic stem cells. Although it has been implicated in cancer progression, its role in breast carcinoma is poorly understood.

MATERIALS AND METHODS

Fifty-seven ductal carcinomas in situ (DCIS), 552 invasive breast carcinomas and 107 corresponding metastatic lymph nodes were evaluated immunohistochemically for the expression of SOX2. Its correlation with clinicopathological features, other biomarker profiles and patients' outcomes were analysed.

RESULTS

SOX2 was detected in 19.0% (105 of 552) of invasive breast carcinomas and 12.3% (seven of 57) of DCIS. Expression correlated with larger tumour size (P = 0.005) and higher grade (P = 0.002). It was associated negatively with ER (P = 0.015) and PR (P = 0.046) expression, but positively with Ki67 index (P = 0.013). Interestingly, it was also associated with neuroendocrine marker expression (synpatophysin and chromogranin/synaptophysin, P = 0.048 and 0.028, respectively). Expression appeared to be independent from that of common stem cell markers, namely CD44, CD24 and aldehyde dehydrogenase 1 (ALDH1). Furthermore, a higher rate of expression was observed in metastatic lymph nodes than in the corresponding primary tumours (P = 0.034). High SOX2 expression was correlated with poor disease-free survival (log-rank=9.489, P = 0.012) and was an independent prognostic factor (HR=2.918, P = 0.015) in patients with high nodal stages.

CONCLUSIONS

In summary, SOX2 expression was related to adverse breast carcinoma profile and poor outcome in selected patient groups.

Fibrotic focus in breast carcinomas: relationship with prognostic parameters and biomarkers

BACKGROUND

Fibrotic focus (FF) has been observed in breast cancers and is suggested to be an important prognostic marker. However, most of these observations were reported by the same group of investigators with similar sample cohort. The relationship of FF and molecular subtypes as well as its associated prognosis has not been elucidated.

METHODS

In this study, 450 cases of breast carcinomas were evaluated for the presence of FF and its association with clinicopathologic parameters and biomarkers.

RESULTS

FF was found in 18.7% of all consecutive cases. FF was associated positively with infiltrative margins (p=0.03) but negatively with extensive in situ component (p<0.001) and lymphocytic infiltration (p<0.001). It was positively associated with estrogen receptor (p=0.007) but negatively with human epidermal growth factor receptor 2 (HER2; p=0.001), epidermal growth factor receptor (p=0.021), Ki-67 (p=0.001), and c-kit (p=0.009). Concomitantly, FF was seen more commonly in luminal A cancers (p<0.001) but less so in luminal B (p=0.045) and HER2-overexpressing cancers (p=0.011). Analysis on patient outcome (median 41 months, range 1-69 months) indicated that FF was an independent poor prognostic factor for disease-free survival (hazard ratio=2.57; 95% confidence interval=1.267-5.214, p=0.009), particularly in the luminal B subtype.

CONCLUSIONS

The findings suggested that FF is associated with specific tumor morphology of an infiltrative, stellate pattern (typical invasive ductal carcinoma-not otherwise specified) rather than round, cellular mass with intense lymphocytic infiltrate (basal-like breast cancers). The poor prognostic implication of FF is additional and independent of other adverse prognostic indicators.

αB-crystallin promotes oncogenic transformation and inhibits caspase activation in cells primed for apoptosis by Rb inactivation

The retinoblastoma (Rb) tumor suppressor gene is frequently inactivated in cancer, resulting in deregulated activation of E2F transcription factors, which promote S-phase entry, p53-dependent and p53-independent apoptosis. Transformed cells evade p53-dependent apoptosis initiated by Rb inactivation by TP53 mutation. However, the mechanisms by which cancer cells circumvent p53-independent apoptosis in this context are poorly understood. Because Rb inactivation primes cells for apoptosis by p53-independent induction of procaspases, we postulated that αB-crystallin, an inhibitor of procaspase-3 activation, would suppress caspase activation in cells with combined Rb and p53 inactivation. Notably, αB-crystallin is commonly expressed in ER/PR/HER2 "triple-negative" breast carcinomas characterized by frequent Rb loss and TP53 mutation. We report that αB-crystallin (-/-) knock out (KO) MEFs immortalized by dominant negative (DN) p53 are resistant to transformation by the adenovirus E1A oncoprotein, which inactivates Rb, while wild-type (WT) MEFs are readily transformed by DN p53 and E1A. αB-crystallin (-/-) KO MEFs stably expressing DN p53 and E1A were more sensitive to chemotherapy-induced caspase-3 activation and apoptosis than the corresponding WT MEFs, despite comparable induction of procaspases by E1A. Similarly, silencing Rb in WT and αB-crystallin (-/-) KO MEFs immortalized by DN p53 increased procaspase levels and sensitized αB-crystallin (-/-) KO MEFs to chemotherapy. Furthermore, silencing αB-crystallin in triple-negative breast cancer cells, which lack Rb and express mutant p53, enhanced chemotherapy sensitivity compared to non-silencing controls. Our results indicate that αB-crystallin inhibits caspase activation in cells primed for apoptosis by Rb inactivation and plays a novel oncogenic role in the context of combined Rb and p53 inactivation.

Molecular alterations in metaplastic breast carcinoma

Metaplastic carcinoma of the breast is a rare and heterogeneous subtype of breast carcinoma with a generally poor outcome, and few therapeutic options once disease recurs or progresses. Metaplastic carcinomas of the breast are usually of a larger size at diagnosis, with less frequent nodal metastasis compared with invasive ductal carcinoma no special type, and lack hormone and HER2 receptor expression. Recent research has revealed some potentially actionable genetic changes in a subset of these rare tumours. However, ongoing efforts to further characterise the genetic basis and the molecular alterations underlying the distinctive morphological and clinical characteristics of these tumours are needed in order to identify new targets for treatment. This review will describe the theories of pathogenesis of metaplastic breast carcinoma, and highlight genetic changes and potential therapeutic targets in this generally poor prognosis malignancy.