Michele Harrison

The fate of chemoresistance in triple negative breast cancer (TNBC)

Background Treatment options for women presenting with triple negative breast cancer (TNBC) are limited due to the lack of a therapeutic target and as a result, are managed with standard chemotherapy such as paclitaxel (Taxol®). Following chemotherapy, the ideal tumour response is apoptotic cell death. Post-chemotherapy, cells can maintain viability by undergoing viable cellular responses such as cellular senescence, generating secretomes which can directly enhance the malignant phenotype. Scope of Review How tumour cells retain viability in response to chemotherapeutic engagement is discussed. In addition we discuss the implications of this retained tumour cell viability in the context of the development of recurrent and metastatic TNBC disease. Current adjuvant and neo-adjuvant treatments available and the novel potential therapies that are being researched are also reviewed. Major conclusions Cellular senescence and cytoprotective autophagy are potential mechanisms of chemoresistance in TNBC. These two non-apoptotic outcomes in response to chemotherapy are inextricably linked and are neglected outcomes of investigation in the chemotherapeutic arena. Cellular fate assessments may therefore have the potential to predict TNBC patient outcome. General Significance Focusing on the fact that cancer cells can bypass the desired cellular apoptotic response to chemotherapy through cellular senescence and cytoprotective autophagy will highlight the importance of targeting non-apoptotic survival pathways to enhance chemotherapeutic efficacy.

Rapid administration of multiple cycles of high-dose myelosuppressive chemotherapy in patients with metastatic breast cancer.

PURPOSE To determine the feasibility and safety of a rapidly cycled sequence of high-dose myelosuppressive chemotherapy courses. PATIENTS AND METHODS Seventeen patients with metastatic breast cancer were treated with two courses of cyclophosphamide (CPA; 3.0 g/m2) supported by granulocyte colony-stimulating factor (G-CSF). Following the first CPA treatment, peripheral-blood leukaphereses commenced when the leukocyte count recovered to 1.0 x 10(9)/L. After hematologic recovery from the second dose of CPA, patients were treated with carboplatin 1,500 mg/m2, etoposide 1,200 mg/m2, and CPA 5.0 g/m2 administered over 3 days. The peripheral-blood progenitors (PBPs) were reinfused 3 days later, and G-CSF was recommenced. RESULTS All patients received the three courses. The median interval between treatments was 14 days (range, 13 to 21). Sixteen of the 34 courses of CPA resulted in admissions for fever. Following the third course, neutrophil counts recovered to 0.5 x 10(9)/L at a median of 9 days (range, 8 to 18) after PBP reinfusion and platelets recovered to 50 x 10(9)/L at a median of 12 days (range, 9 to 102). There were no treatment-related deaths. Flow-cytometric analysis was performed on the leukapheresis collections of eight patients. Seven patients with at least 2.0 x 10(6) CD34+ CD33- cells per kilogram body weight exhibited prompt hematologic recovery. One patient with 0.03 x 10(6) CD34+ CD33- cells was still cytopenic on day 21, and required reinfusion of her back-up marrow. Among seven patients with measurable or assessable disease, there were two complete responses (CRs) and four partial responses (PRs). CONCLUSION These preliminary results suggest that multiple, rapidly cycled courses of high-dose myelosuppressive chemotherapy can be administered. PBPs, harvested during the G-CSF-augmented rebound from CPA-induced cytopenia, produce rapid hematologic recovery in patients undergoing high-dose chemotherapy (HDC). Further follow-up will be necessary to assess the efficacy of this specific regimen in the treatment of metastatic breast cancer.

Cellular senescence induced by aberrant MAD2 levels impacts on paclitaxel responsiveness in vitro.

Background:The mitotic arrest deficiency protein 2 (MAD2) is a key component of the mitotic spindle assembly checkpoint, monitoring accurate chromosomal alignment at the metaphase plate before mitosis. MAD2 also has a function in cellular senescence and in a cells response to microtubule inhibitory (MI) chemotherapy exemplified by paclitaxel.Methods:Using an siRNA approach, the impact of MAD2 down-regulation on cellular senescence and paclitaxel responsiveness was investigated. The endpoints of senescence, cell viability, migration, cytokine expression, cell cycle analysis and anaphase bridge scoring were carried out using standard approaches.Results:We show that MAD2 down-regulation induces premature senescence in the MCF7 breast epithelial cancer cell line. These MAD2-depleted (MAD2↓) cells are also significantly replicative incompetent but retain viability. Moreover, they show significantly higher levels of anaphase bridges and polyploidy compared to controls. In addition, these cells secrete higher levels of IL-6 and IL-8 representing key components of the senescence-associated secretory phenotype (SASP) with the ability to impact on neighbouring cells. In support of this, MAD2↓ cells show enhanced migratory ability. At 72 h after paclitaxel, MAD2↓ cells show a significant further induction of senescence compared with paclitaxel naive controls. In addition, there are significantly more viable cells in the MAD2↓ MCF7 cell line after paclitaxel reflecting the observed increase in senescence.Conclusion:Considering that paclitaxel targets actively dividing cells, these senescent cells will evade cytotoxic kill. In conclusion, compromised MAD2 levels induce a population of senescent cells resistant to paclitaxel.

Growth arrest-specific gene 6 expression in human breast cancer

Growth arrest-specific gene 6 (Gas6), identified in 1995, acts as the ligand to the Axl/Tyro3 family of tyrosine kinase receptors and exerts mitogenic activity when bound to these receptors. Overexpression of the Axl/Tyro3 receptor family has been found in breast, ovarian and lung tumours. Gas6 is upregulated 23-fold by progesterone acting through the progesterone receptor B (PRB). Recently, Gas6 has been shown to be a target for overexpression and amplification in breast cancer. Quantitative real-time PCR analysis was used to determine the levels of Gas6 mRNA expression in 49 primary breast carcinomas. Expression of PRB protein was evaluated immunohistochemically with a commercially available PRB antibody. The results showed a positive association between PRB protein and Gas6 mRNA levels (P=0.04). Gas6 correlated positively with a number of favourable prognostic variables including lymph node negativity (P=0.0002), younger age at diagnosis (P=0.04), smaller size of tumours (P=0.02), low Nottingham prognostic index scores (P=0.03) and low nuclear morphology (P=0.03). This study verifies for the first time the association between PRB and Gas6 in breast cancer tissue.

Quality assurance programme for necropsies.

One hundred and eight consecutive necropsies were entered into a quality assessment of the necropsy service in this hospital using a previously published American protocol. Our results were similar to those of the American series, with confirmation of the major clinical diagnosis in 75%, but a higher rate of unsuspected diagnosis (44%). Necropsy was helpful in 58% of cases. The presentation of selected cases at a monthly conference on causes of death was valuable in correlating clinical and pathological findings, and in helping integrate both services.

Comparison of cytomorphological and architectural heterogeneity in mammographically-detected ductal carcinoma in situ.

Many classification schemes have been proposed for ductal carcinoma in situ. Architectural heterogeneity is widely recognized. Cytonuclear grade appears to have greater prognostic significance than architectural pattern. This study assesses heterogeneity using a classification based on cytological grade and compares this to architectural heterogeneity in mammographically detected ductal carcinoma in situ. One hundred and twelve cases were classified according to architectural subtypes and the carcinoma nuclei were graded. Necrosis and micro‐ calcification were assessed. Eighty‐four percent of ductal carcinomas in situ had a single nuclear grade, whereas only 39% showed a single architectural pattern. High grade nuclei were present in 87% of cases. Necrosis was associated with high nuclear grade. In contrast to architectural heterogeneity, this study shows little ductal carcinoma in situ heterogeneity when classification is based on nuclear grade. Thus, a cytomorphological classification should have the advantage of consistency and reproducibility in comparison to architecture‐based classification systems.

Alpha-T-catenin (CTNNA3) displays tumour specific monoallelic expression in urothelial carcinoma of the bladder

CTNNA3 (alpha‐T‐catenin) is imprinted with preferential monoallelic expression of the maternal allele in placental tissue. The allelic expression pattern of CTNNA3 in adult human cancer is unknown and warrants investigation as CTNNA3 stabilizes cellular adherence, a feature which if compromised could enable cells to acquire an increased capability to detach and invade. We document the frequency of monoallelic versus biallelic expression of CTNNA3 in urothelial carcinoma of the bladder (UCB) samples and compare the observed patterns with that found in the paired normal sample. DNA PCR reactions encompassing a transcribable SNP polymorphism within exon 12 of CTNNA3 were sequence analyzed to identify heterozygous cases. A total of 96 samples were analyzed and included 22 paired normal and tumor UCB cases, 38 formalin fixed paraffin embedded (FFPE) UCB samples consisting of 18 noninvasive pTa tumors and 20 lamina propria invasive pT1 tumors and 14 cell lines of various lineages. RT‐PCR analysis of 35 heterozygous samples followed by sequence analysis allowed monoallelic versus biallelic patterns to be assigned. We have provided the first demonstration that CTNNA3 displays differing allelic expression patterns in UCB. Specifically, 35% (7/20) of informative UCB, showed monoallelic expression, a feature confined to the tumor, with normal urothelial samples displaying biallelic expression. Real time RT‐PCR analyses, demonstrated a significantly lower (P = 0.00039) level of CTNNA3 in the tumor samples compared with the paired normals, all of which displayed biallelic expression. In conclusion, monoallelic and biallelic CTNNA3 expression patterns are demonstrable in tumor bladder tissue, whereas normal cases show only biallelic expression.

Recurrence of Urothelial Carcinoma of the Bladder: A Role for Insulin-Like Growth Factor-II Loss of Imprinting and Cytoplasmic E-Cadherin Immunolocalization

Purpose: This study documents the frequency of insulin-like growth factor-II (IGF-II) loss of imprinting (LOI) in a series of 87 bladder tissues. E-cadherin (CDH1) immunolocalization was also investigated due to the known redistribution of this adherence protein to the cytoplasm following exogenous exposure to IGF-II. Experimental Design: Informative IGF-II cases were identified following DNA-PCR amplification and subsequent sequencing of the transcribable ApaI RFLP in exon 9 of IGF-II. Similar approaches using primer-specific cDNA templates identified the imprinting status of IGF-II in these informative cases. CDH1 cellular localization was assessed on a tissue microarray platform of 114 urothelial carcinoma of the bladder (UCB) cases (70 pTa noninvasive and 44 pT1 lamina propria invasive) using the commercially available Novocastra antibody. Results: IGF-II LOI was evident in 7 of 17 (41%) UCB tumors and 4 of 11 (36%) tumor-associated normal urothelial samples. Two of four pT1 grade 3 tumors, the subject of much debate concerning their suitability for radical cystectomy, showed LOI at the IGF-II locus. In those tumors showing IGF-II LOI, 4 of 7 (57%) displayed concomitant CDH1 cytoplasmic staining. In contrast, only 3 of 10 (30%) IGF-II maintenance of imprinting tumors had concomitant CDH1 cytoplasmic localization. UCB cell lines displaying cytoplasmic CDH1 immunolocalization expressed significantly higher levels of IGF-II (CAL29, HT1376, and RT112) compared with RT4, a cell line displaying crisp membranous CDH1 staining. Finally, cytoplasmic CDH1 staining was an independent predictor of a shorter time to recurrence independent of tumor grade and stage. Conclusions: We suggest that CDH1 cytoplasmic immunolocalization as a result of increased IGF-II levels identifies those nonmuscle invasive presentations most likely to recur and therefore might benefit from more radical nonconserving bladder surgery.

Comparison of chromosome 1 aneusomy detected by interphase cytogenetics and DNA ploidy in carcinoma of the breast

Aneuploidy is an important prognostic factor in many cancers. Chromosome 1 abnormalities are present in most breast carcinomas. These may be part of a non‐specific increase in DNA (aneuploid status) or represent a restricted chromosomal abnormality. In 16 breast carcinomas we compared chromosome 1 aneusomy with ploidy status. Patients were selected from a mammographically screened population and interphase tumour nuclei were studied by in situ hybridization using a chromosome 1 pericentromeric probe. Ploidy status was assessed by image cytometry on disaggregated cells from paraffin blocks. Of eight cases showing chromosome 1 aneusomy, six (75%) were aneuploid and two diploid. Six (75%) of the eight eusomic cases were aneuploid. This study demonstrates that chromosome 1 aneusomy does not always reflect a gross aneuploid status but, in some tumours, is part of a more restricted chromosomal abnormality. Interphase cytogenetics, possibly using a small panel of pericentromeric probes, may be more sensitive than DNA cytometry for detecting abnormal nuclear DNA content.

Comparison of Oestrogen Receptor Assessment in Frozen and Paraffin Sections

Estimation of oestrogen receptors (ER) in breast carcinoma has important therapeutic and prognostic implications. The dextran-coated charcoal (DCC) biochemical technique is being replaced in many institutions by immunohistochemical techniques. The aim of this study was to assess the level of agreement between ER counts in frozen and paraffin sections. Ninety-seven infiltrating breast carcinomas were studied immunohistochemically, for ER in frozen and paraffin sections. Cases were classified as ER-positive if > or = 10% of the tumor cells were positive. Both techniques gave a high level of correlation and agreement. There was complete agreement in classifying cases as ER-positive or ER-negative. ER estimation on only one case was outside 2SD of complete agreement. Oestrogen-receptor content can be assayed satisfactorily in paraffin sections and offers many advantages over the frozen section technique.