Study of suboptimum treatment response: lessons from breast cancer

Clonal evolution in primary breast cancers under sequential epirubicin and docetaxel monotherapy

Background

Subclonal evolution during primary breast cancer treatment is largely unexplored. We aimed to assess the dynamic changes in subclonal composition of treatment-naïve breast cancers during neoadjuvant chemotherapy.

Methods

We performed whole exome sequencing of tumor biopsies collected before, at therapy switch, and after treatment with sequential epirubicin and docetaxel monotherapy in 51 out of 109 patients with primary breast cancer, who were included in a prospectively registered, neoadjuvant single-arm phase II trial.

Results

There was a profound and differential redistribution of subclones during epirubicin and docetaxel treatment, regardless of therapy response. While truncal mutations and main subclones persisted, smaller subclones frequently appeared or disappeared. Reassessment of raw data, beyond formal mutation calling, indicated that the majority of subclones seemingly appearing during treatment were in fact present in pretreatment breast cancers, below conventional detection limits. Likewise, subclones which seemingly disappeared were still present, below detection limits, in most cases where tumor tissue remained. Tumor mutational burden (TMB) dropped during neoadjuvant therapy, and copy number analysis demonstrated specific genomic regions to be systematically lost or gained for each of the two chemotherapeutics.

Conclusions

Sequential epirubicin and docetaxel monotherapy caused profound redistribution of smaller subclones in primary breast cancer, while early truncal mutations and major subclones generally persisted through treatment.

Trial registration

ClinicalTrials.gov, NCT00496795, registered on July 4, 2007.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-022-01090-2.

Nanotechnology Assisted Chemotherapy for Targeted Cancer Treatment: Recent Advances and Clinical Perspectives

Nanotechnology has recently provided exciting platforms in the field of anticancer research with promising potentials for improving drug delivery efficacy and treatment outcomes. Nanoparticles (NPs) possess different advantages over the micro and bulk therapeutic agents, including their capability to carry high payloads of drugs, with prolonged half-life, reduced toxicity of the drugs, and increased targeting efficiency. The wide variety of nanovectors, coupled with different conjugation and encapsulation methods available for different theranostic agents provide promising opportunities to fine-tune the pharmacological properties of these agents for more effective cancer treatment methods. This review discusses applications of NPs-assisted chemotherapy in preclinical and clinical settings and recent advances in design and synthesis of different nanocarriers for chemotherapeutic agents. Moreover, physicochemical properties of different nanocarriers, their impacts on different tumor targeting strategies and effective parameters for efficient targeted drug delivery are discussed. Finally, the current approved NPs-assisted chemotherapeutic agents for clinical applications and under different phases of clinical trials are discussed.

High PTEN gene expression is a negative prognostic marker in human primary breast cancers with preserved p53 function

Purpose

PTEN is an important tumor suppressor in breast cancer. Here, we examined the prognostic and predictive value of PTEN and PTEN pseudogene (PTENP1) gene expression in patients with locally advanced breast cancer given neoadjuvant chemotherapy.

Methods

The association between pretreatment PTEN and PTENP1 gene expression, response to neoadjuvant chemotherapy, and recurrence-free and disease-specific survival was assessed in 364 patients with locally advanced breast cancer given doxorubicin, 5-fluorouracil/mitomycin, or epirubicin versus paclitaxel in three phase II prospective studies. Further, protein expression of PTEN or phosphorylated Akt, S6 kinase, and 4EBP1 was assessed in a subgroup of 187 tumors.

Results

Neither PTEN nor PTENP1 gene expression level predicted response to any of the chemotherapy regimens tested (n = 317). Among patients without distant metastases (n = 282), a high pretreatment PTEN mRNA level was associated with inferior relapse-free (RFS; p = 0.001) and disease-specific survival (DSS; p = 0.003). Notably, this association was limited to patients harboring TP53 wild-type tumors (RFS; p = 0.003, DSS; p = 0.009). PTEN mRNA correlated significantly with PTENP1 mRNA levels (r_s = 0.456, p < 0.0001) and PTEN protein staining (r_s = 0.163, p = 0.036). However, no correlation between PTEN, phosphorylated Akt, S6 kinase or 4EBP1 protein staining, and survival was recorded. Similarly, no correlation between PTENP1 gene expression and survival outcome was observed.

Conclusion

High intratumoral PTEN gene expression was associated with poor prognosis in patients with locally advanced breast cancers harboring wild-type TP53.

Electronic supplementary material

The online version of this article (doi:10.1007/s10549-017-4160-5) contains supplementary material, which is available to authorized users.

Downregulation of STAT3 phosphorylation enhances tumoricidal effect of IL-15-activated dendritic cell against doxorubicin-resistant lymphoma and leukemia via TNF-α

Although disputed by some, increasing evidence suggests that TNF-α synergies with traditional chemotherapeutic drugs to exert a heightened antitumor effect. The present study investigated the antitumor efficacy of recombinant IL-15 in combination with the STAT3 inhibitor cucurbitacin-I in a doxorubicin-resistant murine lymphoma model. The significance of the work is to understand and design effective strategies in doxorubicin resistant lymphomas. TNF-α is downregulated in dendritic cells from mice with Dalton's lymphoma and shows an inverse relationship with disease progression. Doxorubicin-resistant DL cells have elevated levels of Bcl-2 and Mcl-1 and increased phosphorylation of STAT3. These cells are refractory to dendritic cell derived TNF-α. Doxorubicin resistant Dalton's lymphoma is susceptible to dendritic cell derived TNF-α upon stimulation with the STAT3 inhibitor cucurbitacin-I, which downregulates STAT3 and other survival molecules. The combined treatment of low dose of cucurbitacin-I and rIL-15 is ineffective in mice with doxorubicin resistant Dalton's lymphoma, but a similar therapy prolongs the survival of mice transplanted with parental Dalton's lymphoma. Doxorubicin resistant Dalton's lymphoma responds to therapy with high doses of cucurbitacin-I and rIL-15. Dendritic cell derived from mice responded positively to the therapy and regained their tumoricidal properties with respect to growth inhibition and killing of DL tumor cells. Similar to DL, DC derived from CML patients are impaired in TNF-α expression and are unable to restrict the growth of drug-resistant lymphoma and leukemia cells. This combination approach could be used as a new therapeutic strategy for aggressive and highly metastatic doxorubicin resistant lymphoma.

Concomitant inactivation of the p53- and pRB- functional pathways predicts resistance to DNA damaging drugs in breast cancer in vivo

Chemoresistance is the main obstacle to cancer cure. Contrasting studies focusing on single gene mutations, we hypothesize chemoresistance to be due to inactivation of key pathways affecting cellular mechanisms such as apoptosis, senescence, or DNA repair. In support of this hypothesis, we have previously shown inactivation of either TP53 or its key activators CHK2 and ATM to predict resistance to DNA damaging drugs in breast cancer better than TP53 mutations alone. Further, we hypothesized that redundant pathway(s) may compensate for loss of p53‐pathway signaling and that these are inactivated as well in resistant tumour cells. Here, we assessed genetic alterations of the retinoblastoma gene (RB1) and its key regulators: Cyclin D and E as well as their inhibitors p16 and p27. In an exploratory cohort of 69 patients selected from two prospective studies treated with either doxorubicin monotherapy or 5‐FU and mitomycin for locally advanced breast cancers, we found defects in the pRB‐pathway to be associated with therapy resistance (p‐values ranging from 0.001 to 0.094, depending on the cut‐off value applied to p27 expression levels). Although statistically weaker, we observed confirmatory associations in a validation cohort from another prospective study (n = 107 patients treated with neoadjuvant epirubicin monotherapy; p‐values ranging from 7.0 × 10−4 to 0.001 in the combined data sets). Importantly, inactivation of the p53‐and the pRB‐pathways in concert predicted resistance to therapy more strongly than each of the two pathways assessed individually (exploratory cohort: p‐values ranging from 3.9 × 10−6 to 7.5 × 10−3 depending on cut‐off values applied to ATM and p27 mRNA expression levels). Again, similar findings were confirmed in the validation cohort, with p‐values ranging from 6.0 × 10−7 to 6.5 × 10−5 in the combined data sets. Our findings strongly indicate that concomitant inactivation of the p53‐ and pRB‐ pathways predict resistance towards anthracyclines and mitomycin in breast cancer in vivo.

Alterations of pRB's upstream regulators may substitute for RB1 mutations.

The pRB‐pathway may direct response to chemotherapy.

Inactivation of the p53‐and the pRB‐pathways predict resistance to chemotherapy.

Concomitant p53‐and pRB‐pathway inactivation is a strong resistance predictor.

Concomitant p53‐and pRB‐pathway inactivation predicts poor prognosis.

Hyaluronan-CD44 interaction promotes c-Jun signaling and miRNA21 expression leading to Bcl-2 expression and chemoresistance in breast cancer cells

MicroRNA-21 (miR-21) is associated with the development of solid tumors progression including breast cancer. In this study we investigated matrix hyaluronan (HA)-CD44 (a primary HA receptor) interaction with c-Jun N-Terminal Kinase (JNK)/c-Jun signaling in MDA-MB-468 breast cancer cells [a triple-negative (estrogen receptor-negative/progesterone receptor-negative/HER2-negative) breast cancer cell line]. Our results indicated that HA binding to CD44 promotes c-Jun nuclear translocation and transcriptional activation. Further analyses revealed that miR-21 is regulated by an upstream promoter containing AP1 binding site(s), and chromatin immunoprecipitation (CHIP) assays demonstrated that stimulation of miR-21 expression by HA/CD44 interaction is c-Jun-dependent in these breast cancer cells. This process results in an increase of the anti-apoptosis protein Bcl-2 and upregulation of inhibitors of the apoptosis family of proteins (IAPs) as well as chemoresistance in MDA-MB-468 cells. Treatment with c-Jun specific small interfering RNAs effectively blocks HA-mediated c-Jun signaling and abrogates miR-21 production as well as causes downregulation of survival proteins (Bcl-2 and IAPs) and enhancement of chemosensitivity. In addition, our results demonstrated that anti-miR-21 inhibitor not only downregulates Bcl-2/IAP expression but also increases chemosensitivity in HA-treated breast cancer cells. Together, these findings suggest that the HA/CD44-induced c-Jun signaling plays a pivotal role in miR-21 production leading to survival protein (Bcl-2/IAP) upregulation and chemoresistance in triple negative breast cancer cells such as MDA-MB-468 cell line. This novel HA/CD44-mediated c-Jun signaling pathway and miR-21 production provide a new drug target for the future intervention strategies to treat breast cancer.

Aromatase inhibition 2013: clinical state of the art and questions that remain to be solved

Following their successful implementation for the treatment of metastatic breast cancer, the 'third-generation' aromatase inhibitors (anastrozole, letrozole, and exemestane) have now become standard adjuvant endocrine treatment for postmenopausal estrogen receptor-positive breast cancers. These drugs are characterized by potent aromatase inhibition, causing >98% inhibition of estrogen synthesis in vivo. A recent meta-analysis found no difference in anti-tumor efficacy between these three compounds. As of today, aromatase inhibitor monotherapy and sequential treatment using tamoxifen followed by an aromatase inhibitor for a total of 5 years are considered equipotent treatment options. However, current trials are addressing the potential benefit of extending treatment duration beyond 5 years. Regarding side effects, aromatase inhibitors are not found associated with enhanced risk of cardiovascular disease, and enhanced bone loss is prevented by adding bisphosphonates in concert for those at danger of developing osteoporosis. However, arthralgia and carpal tunnel syndrome preclude drug administration among a few patients. While recent findings have questioned the use of aromatase inhibitors among overweight and, in particular, obese patients, this problem seems to focus on premenopausal patients treated with an aromatase inhibitor and an LH-RH analog in concert, questioning the efficacy of LH-RH analogs rather than aromatase inhibitors among overweight patients. Finally, recent findings revealing a benefit from adding the mTOR inhibitor everolimus to endocrine treatment indicate targeted therapy against defined growth factor pathways to be a way forward, by reversing acquired resistance to endocrine therapy.

Formulation design, preparation, and in vitro and in vivo characterizations of β-Elemene-loaded nanostructured lipid carriers

In the present study, nanostructured lipid carriers (NLCs) were prepared and optimized for the intravenous delivery of β-Elemene (β-E). Aqueous dispersions of NLCs were successfully prepared by high-pressure homogenization method using glycerol monostearate as the solid lipid and a mixture of Maisine 35-1 and Labrafil M1944 CS as the liquid lipid. The results revealed that the morphology of the NLCs was spheroidal. The particle size, zeta potential, and entrapment efficiency (EE) for the optimized formulation were observed as 138.9 nm, -20.2 mV, and 82.11%, respectively. X-ray diffraction analysis revealed the formation of less ordered structures in the inner core of the NLC particles. Moreover, the β-E-loaded NLCs were also less irritating and less toxic compared to Elemene injection. In addition, β-E-NLCs showed a significantly higher bioavailability and anti-tumor efficacy than Elemene injection. Taken together, our data indicate that the β-E-NLCs described in this study are well-suited for the intravenous delivery of β-E.

Functional characterisation of p53 mutants identified in breast cancers with suboptimal responses to anthracyclines or mitomycin

BACKGROUND

Approximately 4300 different TP53 mutations have been reported in human cancers. TP53 mutations, in particular those affecting the L2/L3 domains, are associated with resistance to anthracycline or mitomycin treatment in breast cancer patients. While many mutations have been characterised functionally, novel TP53 mutations are continuously reported. Here, we characterise 10 p53 protein variants encoded by mutated TP53 (5 within and 5 outside L2/L3) detected in locally advanced or metastatic breast cancers. Each tumour was previously characterised for response to therapy, allowing comparison between in vivo and in vitro findings.

METHODS

Mutated p53 variants were analysed for their ability to oligomerise with the wild-type protein and their subcellular localisation by immunoprecipitation and immunofluorescence, respectively. Their ability to induce transcription of target genes was determined by qPCR. Cellular growth rate, apoptosis and senescence were monitored by WST-1, TUNEL and beta-galactosidase assays, respectively.

RESULTS

Immunoprecipitation assays revealed each mutant protein to retain binding capacity for wild-type p53, thus potentially acting in a dominant negative manner. Even though each p53 variant located predominantly in the nucleus, the percentage of cells with only nuclear p53 localisation varied between 60% and 90%. None of the p53 variants were able to induce target genes to levels similar to wild-type p53, nor where they able to reduce cellular growth rate, induce apoptosis or senescence similar to wild-type p53 after anthracycline treatment in vitro.

CONCLUSIONS

All the 10 variants studied displayed inferior p53 functionality compared to the wild-type protein.

GENERAL SIGNIFICANCE

Our data add further information characterising the effects of somatic TP53 mutations on p53 protein function and anthracycline resistance in breast cancer.

Preparation of isoliquiritigenin-loaded nanostructured lipid carrier and the in vivo evaluation in tumor-bearing mice

Isoliquiritigenin-loaded nanostructured lipid carrier (ISL-NLC) was constructed and characterized. In vivo antitumor efficacy and immuno-modulation effects of ISL-NLC were evaluated in sarcoma 180 (S180)-bearing and murine hepatoma 22 (H22)-bearing mice model through intraperitoneal (i.p.) administration. The ISL-NLC biodistribution was also investigated in H22-bearing mice. Results demonstrated that the ISL-NLC had a spherical shape with a mean size of (160.73 ± 6.08) nm and encapsulation efficiency of (96.74 ± 1.81)%. ISL released from the nanoparticles was in a sustained manner with an initial burst release. ISL-NLC significantly inhibit tumor growth at 10, 20 and 40 mg/kg levels, and inhibition rates were 75.70%, 82.27% and 83.90% in the S180-bearing mice and 71.49%, 81.11% and 85.62% in the H22-bearing mice, respectively. The biodistribution study showed that ISL concentration of ISL-NLC in tumor is higher 2.5-fold than ISL suspension. The elimination half-life (t1/2), area under the curve (AUC) and the mean residence times (MRTs) of the ISL-NLC was much longer than that of the ISL suspension. As a whole, anticancer effect of ISL encapsulated in NLC was superior to ISL in suspension on H22-bearing and S180-bearing mice at the same dose and was a dose-dependent way, and ISL-NLC improved immunity of ISL. It can be inferred that nanostructured lipid carriers are a promising carrier for cancer therapy using ISL.

Mapping genetic alterations causing chemoresistance in cancer: identifying the roads by tracking the drivers

Although new agents are implemented to cancer therapy, we lack fundamental understandings of the mechanisms of chemoresistance, the main obstacle to cure in cancer. Here we review clinical evidence linking molecular defects to drug resistance across different tumour forms and discuss contemporary experimental evidence exploring these mechanisms. Although evidence, in general, is sparse and fragmentary, merging knowledge links drug resistance, and also sensitivity, to defects in functional pathways having a key role in cell growth arrest or death and DNA repair. As these pathways may act in concert, there is a need to explore multiple mechanisms in parallel. Taking advantage of massive parallel sequencing and other novel high-throughput technologies and base research on biological hypotheses, we now have the possibility to characterize functional defects related to these key pathways and to design a new generation of studies identifying the mechanisms controlling resistance to different treatment regimens in different tumour forms.

Cytotoxicity, toxicity, and anticancer activity of Zingiber officinale Roscoe against cholangiocarcinoma

Cholangiocarcinoma (CCA) is an uncommon adenocarcinoma which arises from the epithelial cells of the bile ducts. The aim of the study was to investigate the cytotoxicity, toxicity, and anticancer activity of a crude ethanolic extract of ginger (Zingiber officinale Roscoe) against CCA. Cytotoxic activity against a CCA cell line (CL-6) was assessed by calcein-AM and Hoechst 33342 assays and anti-oxidant activity was evaluated using the DPPH assay. Investigation of apoptotic activity was performed by DNA fragmentation assay and induction of genes that may be involved in the resistance of CCA to anticancer drugs (MDR1, MRP1, MRP2, and MRP3) was examined by real-time PCR. To investigate anti-CCA activity in vivo, a total of 80 OV and nitrosamine (OV/ DMN)-induced CCA hamsters were fed with the ginger extract at doses of 1000, 3000, and 5000 mg/kg body weight daily or every alternate day for 30 days. Control groups consisting of 10 hamsters for each group were fed with 5-fluorouracil (positive control) or distilled water (untreated control). Median IC50 (concentration that inhibits cell growth by 50%) values for cytotoxicity and anti-oxidant activities of the crude ethanolic extract of ginger were 10.95, 53.15, and 27.86 μg/ml, respectively. More than ten DNA fragments were visualized and up to 7-9 fold up-regulation of MDR1 and MRP3 genes was observed following exposure to the ethanolic extract of ginger. Acute and subacute toxicity tests indicated absence of any significant toxicity at the maximum dose of 5,000 mg/kg body weight given by intragastric gavage. The survival time and survival rate of the CCA-bearing hamsters were significantly prolonged compared to the control group (median of 54 vs 17 weeks). Results from these in vitro and in vivo studies thus indicate promising anticancer activity of the crude ethanolic extract of ginger against CCA with the absence of any significant toxicity. Moreover, MDR1 and MRP3 may be involved in conferring resistance of CCA to the ginger extract.

Methotrexate-loaded SLNs prepared by coacervation technique: in vitro cytotoxicity and in vivo pharmacokinetics and biodistribution

AIM

Recently, 'coacervation' has been proposed as a new method to prepare fatty acid solid lipid nanoparticles (SLNs). The aim of this work was to encapsulate methotrexate, a hydrophilic anticancer drug, within SLNs obtained by coacervation, through hydrophobic ion pairing and to evaluate the potential efficacy in in vitro and in vivo breast tumor models of drug-loaded nanoparticles.

MATERIALS & METHODS

Methotrexate-loaded SLN efficacy was evaluated in vitro towards MCF-7 and Mat B-III cell lines (human and murine breast tumor cell lines). Pharmacokinetics of drug-loaded nanoparticles was evaluated in male Wistar rats and biodistribution in a breast tumor model (Mat B-III) in female Fisher rats.

RESULTS

Drug-loaded SLNs showed an increased cytotoxicity towards MCF-7 and Mat B-III cell lines compared with free drug. After intravenous administration, drug plasmatic concentration was increased and a major drug accumulation within neoplastic tissue was shown when the drug was loaded in SLNs, compared with drug solution alone. Encapsulation of the drug within nanoparticles also increased its oral uptake after duodenal administration.

CONCLUSION

SLNs are promising vehicles for the delivery of methotrexate, since an increase of efficacy in vitro and a preferential accumulation in breast cancer in vivo were shown. Original submitted 29 October 2010; Revision submitted 19 March 2011.

Correlation analysis of p53 protein isoforms with NPM1/FLT3 mutations and therapy response in acute myeloid leukemia

The wild-type tumor-suppressor gene TP53 encodes several isoforms of the p53 protein. However, while the role of p53 in controlling normal cell cycle progression and tumor suppression is well established, the clinical significance of p53 isoform expression is unknown. A novel bioinformatic analysis of p53 isoform expression in 68 patients with acute myeloid leukemia revealed distinct p53 protein biosignatures correlating with clinical outcome. Furthermore, we show that mutated FLT3, a prognostic marker for short survival in AML, is associated with expression of full-length p53. In contrast, mutated NPM1, a prognostic marker for long-term survival, correlated with p53 isoforms β and γ expression. In conclusion, p53 biosignatures contain useful information for cancer evaluation and prognostication.

Properties, engineering and applications of lipid-based nanoparticle drug-delivery systems: current research and advances

Lipid-based drug-delivery systems have evolved from micro- to nano-scale, enhancing the efficacy and therapeutic applications of these delivery systems. Production of lipid-based pharmaceutical nanoparticles is categorized into top-down (fragmentation of particulate material to reduce its average total dimensions) and bottom-up (amalgamation of molecules through chemical interactions creating particles of greater size) production methods. Selection of the appropriate method depends on the physiochemical properties of individual entities within the nanoparticles. The production method also influences the type of nanoparticle formulations being produced. Liposomal formulations and solid-core micelles are the most widely utilized lipid-based nanoparticles, with surface modifications improving their therapeutic outcomes through the production of long-circulating, tissue-targeted and/or pH-sensitive nanoparticles. More recently, solid lipid nanoparticles have been engineered to reduce toxicity toward mammalian cells, while multifunctional lipid-based nanoparticles (i.e., hybrid lipid nanoparticles) have been formulated to simultaneously perform therapeutic and diagnostic functions. This article will discuss novel lipid-based drug-delivery systems, outlining the properties and applications of lipid-based nanoparticles alongside their methods of production. In addition, a comparison between generations of the lipid-based nano-formulations is examined, providing insight into the current directions of lipid-based nanoparticle drug-delivery systems.

Identification and characterization of retinoblastoma gene mutations disturbing apoptosis in human breast cancers

Background

The tumor suppressor pRb plays a key role regulating cell cycle arrest, and disturbances in the RB1 gene have been reported in different cancer forms. However, the literature reports contradictory findings with respect to a pro - versus anti - apoptotic role of pRb, and the consequence of alterations in RB1 to chemotherapy sensitivity remains unclear. This study is part of a project investigating alterations in pivotal genes as predictive factors to chemotherapy sensitivity in breast cancer.

Results

Analyzing 73 locally advanced (stage III) breast cancers, we identified two somatic and one germline single nucleotide changes, each leading to amino acid substitution in the pRb protein (Leu607Ile, Arg698Trp, and Arg621Cys, respectively). This is the first study reporting point mutations affecting RB1 in breast cancer tissue. In addition, MLPA analysis revealed two large multiexon deletions (exons 13 to 27 and exons 21 to 23) with the exons 21-23 deletion occurring in the tumor also harboring the Leu607Ile mutation. Interestingly, Leu607Ile and Arg621Cys point mutations both localize to the spacer region of the pRb protein, a region previously shown to harbor somatic and germline mutations. Multiple sequence alignment across species indicates the spacer to be evolutionary conserved. All three RB1 point mutations encoded nuclear proteins with impaired ability to induce apoptosis compared to wild-type pRb in vitro. Notably, three out of four tumors harboring RB1 mutations displayed primary resistance to treatment with either 5-FU/mitomycin or doxorubicin while only 14 out of 64 tumors without mutations were resistant (p = 0.046).

Conclusions

Although rare, our findings suggest RB1 mutations to be of pathological importance potentially affecting sensitivity to mitomycin/anthracycline treatment in breast cancer.

Molecular basis for therapy resistance

Chemoresistance remains the main reason for therapeutic failure in breast cancer as well as most other solid tumours. While gene expression profiles related to prognosis have been developed, so far use of such signatures as well as single markers has been of limited value predicting drug resistance. Novel technologies, in particular with regard to high through-put sequencing holds great promises for future identification of the key "driver" mechanisms guiding chemosensitivity versus resistance in breast cancer as well as other malignant conditions.

Hyaluronan-CD44 interaction with protein kinase C(epsilon) promotes oncogenic signaling by the stem cell marker Nanog and the Production of microRNA-21, leading to down-regulation of the tumor suppressor protein PDCD4, anti-apoptosis, and chemotherapy resistance in breast tumor cells

Multidrug resistance and disease relapse is a challenging clinical problem in the treatment of breast cancer. In this study, we investigated the hyaluronan (HA)-induced interaction between CD44 (a primary HA receptor) and protein kinase Cepsilon (PKCepsilon), which regulates a number of human breast tumor cell functions. Our results indicate that HA binding to CD44 promotes PKCepsilon activation, which, in turn, increases the phosphorylation of the stem cell marker, Nanog, in the breast tumor cell line MCF-7. Phosphorylated Nanog is then translocated from the cytosol to the nucleus and becomes associated with RNase III DROSHA and the RNA helicase p68. This process leads to microRNA-21 (miR-21) production and a tumor suppressor protein (e.g. PDCD4 (program cell death 4)) reduction. All of these events contribute to up-regulation of inhibitors of apoptosis proteins (IAPs) and MDR1 (multidrug-resistant protein), resulting in anti-apoptosis and chemotherapy resistance. Transfection of MCF-7 cells with PKCepsilon or Nanog-specific small interfering RNAs effectively blocks HA-mediated PKCepsilon-Nanog signaling events, abrogates miR-21 production, and increases PDCD4 expression/eIF4A binding. Subsequently, this PKCepsilon-Nanog signaling inhibition causes IAP/MDR1 down-regulation, apoptosis, and chemosensitivity. To further evaluate the role of miR-21 in oncogenesis and chemoresistance, MCF-7 cells were also transfected with a specific anti-miR-21 inhibitor in order to silence miR-21 expression and inhibit its target functions. Our results indicate that anti-miR-21 inhibitor not only enhances PDCD4 expression/eIF4A binding but also blocks HA-CD44-mediated tumor cell behaviors. Thus, this newly discovered HA-CD44 signaling pathway should provide important drug targets for sensitizing tumor cell apoptosis and overcoming chemotherapy resistance in breast cancer cells.

Hyaluronan-mediated CD44 interaction with p300 and SIRT1 regulates beta-catenin signaling and NFkappaB-specific transcription activity leading to MDR1 and Bcl-xL gene expression and chemoresistance in breast tumor cells

In this study we have investigated hyaluronan (HA)-mediated CD44 (an HA receptor) interactions with p300 (a histone acetyltransferase) and SIRT1 (a histone deacetylase) in human breast tumor cells (MCF-7 cells). Specifically, our results indicate that HA binding to CD44 up-regulates p300 expression and its acetyltransferase activity that, in turn, promotes acetylation of beta-catenin and NFkappaB-p65 leading to activation of beta-catenin-associated T-cell factor/lymphocyte enhancer factor transcriptional co-activation and NFkappaB-specific transcriptional up-regulation, respectively. These changes then cause the expression of the MDR1 (P-glycoprotein/P-gp) gene and the anti-apoptotic gene Bcl-x(L) resulting in chemoresistance in MCF-7 cells. Our data also show that down-regulation of p300, beta-catenin, or NFkappaB-p65 in MCF-7 cells (by transfecting cells with p300-, beta-catenin-, or NFkappaB-p65-specific small interfering RNA) inhibits the HA/CD44-mediated beta-catenin/NFkappaB-p65 acetylation and abrogates the aforementioned transcriptional activities. Subsequently, there is a significant decrease in both MDR1 and Bcl-x(L) gene expression and an enhancement in caspase-3 activity and chemosensitivity in the breast tumor cells. Further analyses indicate that activation of SIRT1 (deacetylase) by resveratrol (a natural antioxidant) induces SIRT1-p300 association and acetyltransferase inactivation, leading to deacetylation of HA/CD44-induced beta-catenin and NFkappaB-p65, inhibition of beta-catenin-T-cell factor/lymphocyte enhancer factor and NFkappaB-specific transcriptional activation, and the impairment of MDR1 and Bcl-x(L) gene expression. All these multiple effects lead to an activation of caspase-3 and a reduction of chemoresistance. Together, these findings suggest that the interactions between HA/CD44-stimulated p300 (acetyltransferase) and resveratrol-activated SIRT1 (deacetylase) play pivotal roles in regulating the balance between cell survival versus apoptosis, and multidrug resistance versus sensitivity in breast tumor cells.

Methylated genes as new cancer biomarkers

Aberrant hypermethylation of promoter regions in specific genes is a key event in the formation and progression of cancer. In at least some situations, these aberrant alterations occur early in the formation of malignancy and appear to be tumour specific. Multiple reports have suggested that measurement of the methylation status of the promoter regions of specific genes can aid early detection of cancer, determine prognosis and predict therapy responses. Promising DNA methylation biomarkers include the use of methylated GSTP1 for aiding the early diagnosis of prostate cancer, methylated PITX2 for predicting outcome in lymph node-negative breast cancer patients and methylated MGMT in predicting benefit from alkylating agents in patients with glioblastomas. However, prior to clinical utilisation, these findings require validation in prospective clinical studies. Furthermore, assays for measuring gene methylation need to be standardised, simplified and evaluated in external quality assurance programmes. It is concluded that methylated genes have the potential to provide a new generation of cancer biomarkers.

Strength and weakness of phase I to IV trials, with an emphasis on translational aspects

Although phase I to III trials represent the standard for introducing new drugs to clinical therapy, there has been increasing demand for translational research in oncology over the past decade. Thus, for most novel therapies such as 'targeted agents', a critical aspect for drug development in oncology has been to select the right patients for therapy. Translational research plays a pivotal role, not only in phase II trials but also in phase I and III and even in phase IV trials. The importance of distinguishing between our translational 'aims' in phase II and phase III trials is emphasized. Although translational research in phase III trials aims to identify optimal markers for clinical use, phase II studies may represent an optimal setting to explore tumour biology and the mechanisms of drug resistance in depth.

CHEK2 mutations affecting kinase activity together with mutations in TP53 indicate a functional pathway associated with resistance to epirubicin in primary breast cancer

Background

Chemoresistance is the main obstacle to cure in most malignant diseases. Anthracyclines are among the main drugs used for breast cancer therapy and in many other malignant conditions. Single parameter analysis or global gene expression profiles have failed to identify mechanisms causing in vivo resistance to anthracyclines. While we previously found TP53 mutations in the L2/L3 domains to be associated with drug resistance, some tumors harboring wild-type TP53 were also therapy resistant. The aim of this study was; 1) To explore alterations in the TP53 gene with respect to resistance to a regular dose epirubicin regimen (90 mg/m² every 3 week) in patients with primary, locally advanced breast cancer; 2) Identify critical mechanisms activating p53 in response to DNA damage in breast cancer; 3) Evaluate in vitro function of Chk2 and p14 proteins corresponding to identified mutations in the CHEK2 and p14^(ARF) genes; and 4) Explore potential CHEK2 or p14^(ARF) germline mutations with respect to family cancer incidence.

Methods and Findings

Snap-frozen biopsies from 109 patients collected prior to epirubicin (as preoperative therapy were investigated for TP53, CHEK2 and p14^(ARF) mutations by sequencing the coding region and p14^(ARF) promoter methylations. TP53 mutastions were associated with chemoresistance, defined as progressive disease on therapy (p = 0.0358; p = 0.0136 for mutations affecting p53 loop domains L2/L3). Germline CHEK2 mutations (n = 3) were associated with therapy resistance (p = 0.0226). Combined, mutations affecting either CHEK2 or TP53 strongly predicted therapy resistance (p = 0.0101; TP53 mutations restricted to the L2/L3 domains: p = 0.0032). Two patients progressing on therapy harbored the CHEK2 mutation, Arg95Ter, completely abrogating Chk2 protein dimerization and kinase activity. One patient (Epi132) revealed family cancer occurrence resembling families harboring CHEK2 mutations in general, the other patient (epi203) was non-conclusive. No mutation or promoter hypermethylation in p14^(ARF) were detected.

Conclusion

This study is the first reporting an association between CHEK2 mutations and therapy resistance in human cancers and to document mutations in two genes acting direct up/down-stream to each other to cause therapy failure, emphasizing the need to investigate functional cascades in future studies.

Pathway based analysis of SNPs with relevance to 5-FU therapy: relation to intratumoral mRNA expression and survival

Genetic factors are thought to play a role in resistance towards chemotherapeutic agents such as 5-fluorouracil (5-FU). Approximately 30 genes are directly or indirectly involved in 5-FU metabolism, and genetic variation in any of these may contribute to anti-tumor response. Polymorphisms in these genes were analyzed in relation to tumoral mRNA levels of 5-FU metabolizing genes, response to chemotherapy and survival. A total of 21 genetic variants were studied in 35 breast cancer patients treated with 5-FluoroUracil, mitomycin (FUMI) and in a similar cohort of 90 doxorubicin treated breast cancer patients. Genotype distributions were compared using 109 healthy controls. No significant association was found between any polymorphisms and response to chemotherapy as measured by shrinkage of tumor. However, carriers of 3 copies of the TYMS 5'UTR repeat had shorter survival than noncarriers (p = .048) in the FUMI treatment group, but not in the doxorubicin treated group. Carriers of 3 copies of the repeat were also more frequently observed in both patients groups than in healthy controls (p = .034). Several highly significant associations were observed between genotypes and expression levels of 5-FU metabolizing genes. A SNP in codon 72 of TP53 was revealed to be a key regulator of 5-FU metabolizing genes such as DHFR and MTHFR, constituting 50% of all significant associations observed after FUMI therapy. These data suggest that 3 copies of the TYMS 5'UTR repeat may give a treatment specific reduced survival in breast cancer patients, and that TP53 may have a direct, allele specific, role in 5-FU mediated response.

Role of tumor markers in patients with solid cancers: A critical review

The measurement of tumor markers is currently one of the most rapidly growing areas in laboratory medicine. Lack of sensitivity and specificity preclude the use of most existing markers for the early detection of malignancy. For patients with diagnosed malignancy, however, markers are potentially useful in determining prognosis, predicting therapeutic response, maintaining surveillance following curative surgery and monitoring therapy in advanced disease. Clinically useful markers include CEA in the surveillance of patients with diagnosed colorectal cancer, AFP and HCG in the management of patients with non-seminomatous germ cell tumors, HCG in the management of patients with trophoblastic disease, CA 125 for monitoring therapy in patients with ovarian cancer, estrogen receptors for predicting response to hormone therapy in breast cancer and HER-2 for the identification of women with breast cancer likely to respond to trastuzumab (Herceptin). Although widely used, the impact of PSA screening in reducing mortality from prostate cancer remains to be shown.

Breast cancer prognostication and prediction in the postgenomic era

Expanding knowledge, together with implementation of new techniques, has fuelled the area of translational medical research aiming at improving prognostication as well as prediction in cancer therapy. At the same time, new discoveries have revealed a biological complexity we were unaware of only a decade ago. Thus, we are faced with novel challenges with respect to how we may explore issues such as prognostication and predict drug resistance in vivo. While microarray analysis exploring expression of thousands of genes in concert represents a major methodological advancement, discoveries such as the finding of different mechanisms of epigenetic silencing, intronic mutations, that most gene transcripts in the human genome are subject to alternative splicing and that hypersplicing seems to be a tumour-related phenomenon, exemplifies a complex pathology that may not be explored with use of single analytical methods only. This paper discusses clinical settings for studying drug resistance in vivo together with a discussion of contemporary biology in this field. Notably, each individual parameter which has been found correlated to drug resistance in vivo so far represents either a direct drug target or a factor involved in DNA repair or apoptosis. On the basis of these findings, we suggest drug resistance may be explored on the basis of upfront biological hypotheses.

Gene expression profiles do not consistently predict the clinical treatment response in locally advanced breast cancer

Neoadjuvant treatment offers an opportunity to correlate molecular variables to treatment response and to explore mechanisms of drug resistance in vivo. Here, we present a statistical analysis of large-scale gene expression patterns and their relationship to response following neoadjuvant chemotherapy in locally advanced breast cancers. We analyzed cDNA expression data from 81 tumors from two patient series, one treated with doxorubicin alone (51) and the other treated with 5-fluorouracil and mitomycin (30), and both were previously studied for correlations between TP53 status and response to therapy. We observed a low frequency of progressive disease within the luminal A subtype from both series (2 of 36 versus 13 of 45 patients; P = 0.0089) and a high frequency of progressive disease among patients with luminal B type tumors treated with doxorubicin (5 of 8 patients; P = 0.0078); however, aside from these two observations, no other consistent associations between response to chemotherapy and tumor subtype were observed. These specific associations could possibly be explained by covariance with TP53 mutation status, which also correlated with tumor subtype. Using supervised analysis, we could not uncover a gene profile that could reliably (&gt;70% accuracy and specificity) predict response to either treatment regimen. [Mol Cancer Ther 2006;5(11):2914–8]

A new polymer-lipid hybrid nanoparticle system increases cytotoxicity of doxorubicin against multidrug-resistant human breast cancer cells

PURPOSE

This work is intended to develop and evaluate a new polymer-lipid hybrid nanoparticle system that can efficiently load and release water-soluble anticancer drug doxorubicin hydrochloride (Dox) and enhance Dox toxicity against multidrug-resistant (MDR) cancer cells.

METHODS

Cationic Dox was complexed with a new soybean-oil-based anionic polymer and dispersed together with a lipid in water to form Dox-loaded solid lipid nanoparticles (Dox-SLNs). Drug loading and release properties were measured spectrophotometrically. The in vitro cytotoxicity of Dox-SLN and the excipients in an MDR human breast cancer cell line (MDA435/LCC6/MDR1) and its wild-type line were evaluated by trypan blue exclusion and clonogenic assays. Cellular uptake and retention of Dox were determined with a microplate fluorometer.

RESULTS

Dox-SLNs were prepared with a drug encapsulation efficiency of 60-80% and a particle size range of 80-350 nm. About 50% of the loaded drug was released in the first few hours and an additional 10-20% in 2 weeks. Treatment of the MDR cells with Dox-SLN resulted in over 8-fold increase in cell kill when compared to Dox solution treatment at equivalent doses. The blank SLN and the excipients exhibited little cytotoxicity. The biological activity of the released Dox remained unchanged from fresh, free Dox. Cellular Dox uptake and retention by the MDR cells were both significantly enhanced (p < 0.05) when Dox was delivered in Dox-SLN form.

CONCLUSIONS

The new polymer-lipid hybrid nanoparticle system is effective for delivery of Dox and enhances its efficacy against MDR breast cancer cells.

In vivo model for research of breast cancer biomarkers

The preoperative (neoadjuvant) setting of breast cancer treatment is an optimal in vivo model by which to allow the characterization of biomarker expression pattern with the tumor remaining in situ throughout treatment as an in vivo measure of response to particular therapy. Elucidating surrogate molecular or cellular markers of tumor response to therapy, may provide biological insight into both, the mechanism of tumor growth dynamics and drug sensitivity/resistance. Owing to the knowledge that many drugs are effective on actively proliferating cells and more intriguingly, that many anticancer agents with differing modes of action achieve cytotoxic effects by inducing apoptosis, has lead to a reappraisal of traditional views of tumor response/resistance to cytotoxic drugs in vivo. Accordingly, this review article will focus on discussing apoptosis phenomena and the p53 and bcl-2 protein as its regulators of principal impor?tance; a cell proliferation determined by the Ki-67 expression, as the major counterbalancing process to apoptosis is also considered. This paper reviews the rationale for the use of these proteins as indices of tumor response to therapy, as well as the published literature regarding their clinical relevance. So far, no firm conclusions can be made concerning their predictive utility. .

Aromatase inhibition: translation into a successful therapeutic approach

The development of the novel third-generation aromatase inhibitors and inactivators for breast cancer treatment is one of the most successful contemporary achievements in cancer therapy. Parallel to studies evaluating toxicity and clinical efficacy in metastatic disease, the endocrine effects of multiple compounds were evaluated, leading to the identification of the highly potent third-generation aromatase inhibitors based on estrogen deprivation and aromatase inhibition in vivo. Thus, translational studies have been of vital importance identifying the unique characteristics of these compounds. Whereas first- and second-generation aromatase inhibitors inhibit estrogen synthesis in vivo by up to 90%, the third-generation compounds anastrozole, exemestane, and letrozole were found to cause > or =98% aromatase inhibition. This article summarizes and discusses the "translational research" that provided the background for the implementation of the third-generation aromatase inhibitors and inactivators into large clinical trials. The need for future translational research exploiting the mechanisms of resistance to these compounds for future improvement of endocrine therapy is emphasized.

Drug sensitivity and drug resistance profiles of human intrahepatic cholangiocarcinoma cell lines

AIM: To study the effect of a number of chemotherapeutic drugs on five human intrahepatic cholangiocarcinoma (CCA) cell lines. The expressions of genes that have been proposed to influence the resistance of chemotherapeutic drugs including thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), glutathione-S-transferase P1 (GSTP1), multidrug resistance protein (MDR1) and multidrug resistance-associated proteins (MRPs) were also determined.

METHODS: Five human CCA cell lines (KKU-100, KKU-M055, KKU-M156, KKU-M214 and KKU-OCA17) were treated with various chemotherapeutic drugs and growth inhibition was determined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. Semi-quantitative levels of gene expression were determined by a reverse transcriptase polymerase chain reaction (RT-PCR). Results of IC₅₀ values and the ratios of gene expression were analyzed by linear regression to predict their relationship.

RESULTS: Among five CCA cell lines, KKU-M055 was the most sensitive cell line towards all chemotherapeutic drugs investigated, particularly taxane derivatives with IC₅₀ values of 0.02-3 nmol/L, whereas KKU-100 was apparently the least sensitive cell line. When compared to other chemotherapeutic agents, doxorubicin and pirarubicin showed the lowest IC₅₀ values (<5 μmol/L) in all five CCA cell lines. Results from RT-PCR showed that TS, MRP1, MRP3 and GSTP1 were highly expressed in these five CCA cell lines while DPD and MRP2 were only moderately expressed. It should be noted that MDR1 expression was detected only in KKU-OCA17 cell lines. A strong correlation was only found between the level of MRP3 expression and the IC₅₀ values of etoposide, doxorubicin and pirarubicin (r = 0.86-0.98, P<0.05).

CONCLUSION: Sensitivity to chemotherapeutic agents is not associated with the histological type of CCA. Choosing of the appropriate chemotherapeutic regimen for the treatment of CCA requires knowledge of drug sensitivity. MRP3 was correlated with resistance of CCA cell lines to etoposide, doxorubicin and pirarubicin, whereas other chemotherapeutic drugs showed no association. The role of this multidrug resistance-associated protein, MRP3, in chemotherapeutic resistance in CCA patients needs to be further investigated.

Genomics in breast cancer—therapeutic implications

The introduction of DNA microarray techniques has had dramatic implications on cancer research, allowing researchers to analyze expression of multiple genes in concert and relate the findings to clinical parameters. The main discoveries in breast cancer, as well as in other malignancies, have so far been with respect to two key issues. First, individual tumors arising from the same organ may be grouped into distinct classes based on their gene expression profiles, independent of stage and grade. Second, the biologic relevance of such classification is corroborated by significant prognostic impact. We review how the use of microarray technologies can provide unique possibilities to explore the mechanisms of tumor behavior in vivo that will allow evaluation of prognosis and, potentially, drug resistance. However, in spite of recent advances, we are not yet at a stage where the use of these techniques should be implemented for routine clinical use, whether to define prognostic factors or to predict sensitivity to therapy.

Alternative splicing and mutation status of CHEK2 in stage III breast cancer

The DNA damage checkpoint kinase, CHK2, promotes growth arrest or apoptosis through phosphorylating targets such as Cdc25A, Cdc25C, BRCA1, and p53. Both germline and somatic loss-of-function CHEK2 mutations occur in human tumours, the former linked to the Li-Fraumeni syndrome, and the latter found in diverse types of sporadic malignancies. Here we examined the status of CHK2 by genetic and immunohistochemical analyses in 53 breast carcinomas previously characterized for TP53 status. We identified two CHEK2 mutants, 470T>C (Ile157Thr), and a novel mutation, 1368insA leading to a premature stop codon in exon 13. The truncated protein encoded by CHEK2 carrying the 1368insA was stable yet mislocalized to the cytoplasm in tumour sections and when ectopically expressed in cultured cells. Unexpectedly, we found CHEK2 to be subject to extensive alternative splicing, with some 90 splice variants detected in our tumour series. While all cancers expressed normal-length CHEK2 mRNA together with the spliced transcripts, we demonstrate and/or predict some of these splice variants to lack CHK2 function and/or localize aberrantly. We conclude that cytoplasmic sequestration may represent a novel mechanism to disable CHK2, and propose to further explore the significance of the complex splicing patterns of this tumour suppressor gene in oncogenesis.

Genetic and epigenetic changes in p21 and p21B do not correlate with resistance to doxorubicin or mitomycin and 5-fluorouracil in locally advanced breast cancer

PURPOSE

The cyclin-dependent kinase inhibitor p21 acts as a main executor of p53-induced growth arrest. Recently, a second transcript, p21B, was found to code for a protein expressing proapoptotic activity. We investigated p21 and p21B for mutations and epigenetic silencing in locally advanced breast cancers treated with doxorubicin or 5-fluorouracil/mitomycin and correlated our findings with treatment response and TP53 status.

EXPERIMENTAL DESIGN

We used reverse transcription-PCR to analyze p21/p21B mutation status in 73 breast cancer samples. The p21 promoter region was sequenced and analyzed for hypermethylations by methylation-specific PCR. In addition, a selection of patients were analyzed for mutations in the p21B promoter.

RESULTS

The p21 gene was neither mutated nor silenced by promoter hypermethylation in any of the tumors examined. One patient harbored a novel p21 splice variant in addition to the wild-type transcript. We observed two base substitutions in the p21 transcript, C93A and G251A, each affecting six patients (8.2%). The G251A variant had not been reported previously. In 12 patients (16.4%), we observed a novel base substitution, T35C, in p21B. All three base substitutions were observed in lymphocyte DNA and therefore considered polymorphisms. The polymorphisms did not correlate with p21 staining index, treatment response to doxorubicin or 5-fluorouracil/mitomycin, or TP53 status.

CONCLUSIONS

Our findings do not suggest that genetic or epigenetic disturbances in p21 or p21B cause resistance to doxorubicin or mitomycin/5-fluorouracil in breast cancer. Future studies should assess potential associations between these novel polymorphisms and breast cancer risk.