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Over the last 10 years there has been an explosion of information about the molecular biology of cancer. A challenge in oncology is to translate this information into advances in patient care. While there are well-formed routes for translating new molecular information into drug therapy, the routes for translating new information into sensitive and specific diagnostic, prognostic and predictive tests are still being developed. Similarly, the science of using tumor molecular profiles to select clinical trial participants or to optimize therapy for individual patients is still in its infancy. This review will summarize the current technologies for predicting treatment response and prognosis in cancer medicine, and outline what the future may hold. It will also highlight the potential importance of methods that can integrate molecular, histopathological and clinical information into a synergistic understanding of tumor progression. While these possibilities are without doubt exciting, significant challenges remain if we are to implement them with a strong evidence base in a widely available and cost-effective manner.

The TP53 gene locus is capable of producing multiple RNA transcripts encoding the different p53 protein isoforms. We recently described multiplex long amplicon droplet digital PCR (ddPCR) assays to quantify seven of eight TP53 reference transcripts in human tumors. Here, we describe a new long amplicon ddPCR assay to quantify expression of the eighth TP53 reference transcript encoding ∆40p53α. We then applied these assays, alongside DNA sequencing of the TP53 gene locus, to tumors from a cohort of New Zealand (NZ) breast cancer patients. We found a high prevalence of mutations at TP53 splice sites in the NZ breast cancer cohort. Mutations at TP53 intron 4 splice sites were associated with overexpression of ∆133TP53 transcripts. Cox proportional hazards survival analysis showed that interplay between TP53 mutation status and expression of TP53 transcript variants was significantly associated with patient outcome, over and above standard clinical and pathological information. In particular, patients with no TP53 mutation and a low ratio of TP53 transcripts t2 to t1, which derive from alternative intron 1 acceptor splice sites, had a remarkably good outcome. We suggest that this type of analysis, integrating mutation and transcript expression, provides a step-change in our understanding of TP53 in cancer.

The nucleic acid-binding protein YB-1, a member of the cold-shock domain protein family, has been implicated in the progression of breast cancer and is associated with poor patient survival. YB-1 has sequence similarity to LIN28, another cold-shock protein family member, which has a role in the regulation of small noncoding RNAs (sncRNAs) including microRNAs (miRNAs). Therefore, to investigate whether there is an association between YB-1 and sncRNAs in breast cancer, we investigated whether sncRNAs were bound by YB-1 in two breast cancer cell lines (luminal A-like and basal cell-like), and whether the abundance of sncRNAs and mRNAs changed in response to experimental reduction of YB-1 expression. RNA-immunoprecipitation with an anti-YB-1 antibody showed that several sncRNAs are bound by YB-1. Some of these were bound by YB-1 in both breast cancer cell lines; others were cell-line specific. The small RNAs bound by YB-1 were derived from various sncRNA families including miRNAs such as let-7 and miR-320, transfer RNAs, ribosomal RNAs and small nucleolar RNAs (snoRNA). Reducing YB-1 expression altered the abundance of a number of transcripts encoding miRNA biogenesis and processing proteins but did not alter the abundance of mature or precursor miRNAs. YB-1 binds to specific miRNAs, snoRNAs and tRNA-derived fragments and appears to regulate the expression of miRNA biogenesis and processing machinery. We propose that some of the oncogenic effects of YB-1 in breast cancer may be mediated through its interactions with sncRNAs.

Nuclear localization and high levels of the Y-box-binding protein YB1 appear to be important indicators of drug resistance and tumor prognosis. YB1 also interacts with the p53 tumor suppressor protein. In this paper, we have continued to explore YB1/p53 interactions. We report that transcriptionally active p53 is required for nuclear localization of YB1. We go on to show that nuclear YB1 regulates p53 function. Our data demonstrate that YB1 inhibits the ability of p53 to cause cell death and to transactivate cell death genes, but does not interfere with the ability of p53 to transactivate the CDKN1A gene, encoding the kinase p21 WAF1/CIP1 required for cell cycle arrest, nor the MDM2 gene. We also show that nuclear YB1 is associated with a failure to increase the level of the Bax protein in normal mammary epithelial cells after stress activation of p53. Together these data suggest that (nuclear) YB1 selectively alters p53 activity, which may in part provide an explanation for the correlation of nuclear YB1 with drug resistance and poor tumor prognosis.

Nine of the ten papers published in this Special Issue explore various aspects of the multifunctional protein Y-box binding protein-1 (YB-1) and its role in cancer [...].Nine of the ten papers published in this Special Issue explore various aspects of the multifunctional protein Y-box binding protein-1 (YB-1) and its role in cancer [...].

The literature concerning the subcellular location of Y-box binding protein 1 (YB-1), its abundance in normal and cancer tissues, and its prognostic significance is replete with inconsistencies. An explanation for this could be due in part to the use of different antibodies in immunohistochemical and immunofluorescent labeling of cells and tissues. The inconsistencies could also be due to poor resolution of immunohistochemical data. We analyzed two cohorts of breast tumours for both abundance and subcellular location of YB-1 using three different antibodies; two targeting N-terminal epitopes (AB-a and AB-b) and another (AB-c) targeting a C-terminal epitope. We also investigated stress-induced nuclear translocation of YB-1 in cell culture. We report that both AB-a and AB-c detected increased YB-1 in the cytoplasm of high-grade breast cancers, and in those lacking estrogen and progesterone receptors; however the amount of YB-1 detected by AB-a in these cancers is significantly greater than that detected by AB-c. We confirm our previously published findings that AB-b is also detecting hnRNP A1, and cannot therefore be used to reliably detect YB-1 by immunohistochemistry. We also report that AB-a detected nuclear YB-1 in some tumour tissues and stress treated cells, whereas AB-c did not. To understand this, cancer cell lines were analyzed using native gel electrophoresis, which revealed that the antibodies detect different complexes in which YB-1 is a component. Our data suggest that different YB-1 antibodies show different staining patterns that are determined by the accessibility of epitopes, and this depends on the nature of the YB-1 complexes. It is important therefore to standardize the protocols if YB-1 is to be used reproducibly as a prognostic guide for different cancers.

Objectives: To perform the first national analysis of demographic and clinicopathological features associated with the HER2 positive, HER2-low, and HER2-zero invasive breast cancers in New Zealand. The study will reveal the proportion of women who may benefit from new HER2-targeted antibody drug conjugate (ADC) therapies. Methods: Utilising data from Te Rēhita Mate Ūtaetae (Breast Cancer Foundation NZ National Register), the study analysed data from women diagnosed with invasive breast cancer over a 21-year period. The HER2 status of tumours was classified into three categories—HER2-zero, HER2-low, HER2-positive. Results: From 2009–2021, 94% of women underwent HER2 testing, with 14% diagnosed with HER2-positive breast cancer. For advanced-stage disease, 38% of those formerly classified as HER2-negative were reclassified as HER2-low. Including HER2-positive breast cancers, this indicates that 60% of women with advanced breast cancer may potentially benefit from the new HER2-directed ADCs (approximately 120 women per year). Conclusions: The findings suggest a significant proportion of women with invasive breast cancer in New Zealand could benefit from new HER2-targeted treatments. There is a need to standardise HER2 testing to enhance personalised treatment and improve outcomes.

Background The use of RNAi to analyse gene function in vitro is now widely applied in biological research. However, several difficulties are associated with its use in vivo , mainly relating to inefficient delivery and non-specific effects of short RNA duplexes in animal models. The latter can lead to false positive results when real-time RT-qPCR alone is used to measure target mRNA knockdown. Findings We observed that detection of an apparent siRNA-mediated knockdown in vivo was dependent on the primers used for real-time RT-qPCR measurement of the target mRNA. Two siRNAs specific for RRM1 with equivalent activity in vitro were administered to A549 xenografts via intratumoural injection. In each case, apparent knockdown of RRM1 mRNA was observed only when the primer pair used in RT-qPCR flanked the siRNA cleavage site. This false-positive result was found to result from co-purified siRNA interfering with both reverse transcription and qPCR. Conclusions Our data suggest that using primers flanking the siRNA-mediated cleavage site in RT-qPCR-based measurements of mRNA knockdown in vivo can lead to false positive results. This is particularly relevant where high concentrations of siRNA are introduced, particularly via intratumoural injection, as the siRNA may be co-purified with the RNA and interfere with downstream enzymatic steps. Based on these results, using primers flanking the siRNA target site should be avoided when measuring knockdown of target mRNA by real-time RT-qPCR.

Nuclear localization and high levels of the Y-box binding protein YB1 appear to be important indicators of drug resistance and tumor prognosis. YB1 also interacts with the p53 tumor suppressor protein. In this paper, we explore a role for p53 in the nuclear localization of YB1. We report that various genotoxic stresses induce nuclear localization of YB1 in a small proportion of treated cells, but only in cells with wild-type p53. We go on to show directly that functional p53 is required for YB1 to translocate to the nucleus. Tumor-associated p53 mutants however are attenuated for YB1 nuclear localization as are mutants mutated in the proline-rich domain of p53. These data link the DNA-damage response of p53 to YB1 nuclear translocation. In addition, we find that YB1 inhibits p53-induced cell death and its ability to trans-activate promoters of genes involved in cell death signaling. Together these data suggest that some forms of p53 cause YB1 to accumulate in the nucleus, which in turn inhibits p53 activity. These results provide a possible explanation for the correlation of nuclear YB1 with drug resistance and poor prognosis in some tumor types, and for the first time implicate p53 in the process of nuclear translocation.

Background Circulating tumour DNA (ctDNA) analysis promises to improve the clinical care of people with cancer, address health inequities and guide translational research. This observational cohort study used ctDNA to follow 29 patients with advanced-stage cutaneous melanoma through multiple cycles of immunotherapy. Method A melanoma-specific ctDNA next-generation sequencing (NGS) panel, droplet digital polymerase chain reaction (ddPCR) and mass spectrometry analysis were used to identify ctDNA mutations in longitudinal blood plasma samples from Aotearoa New Zealand (NZ) patients receiving immunotherapy for melanoma. These technologies were used in conjunction to identify the breadth and complexity of tumour genomic information that ctDNA analysis can reliably report. Results During the course of immunotherapy treatment, a high level of dynamic mutational complexity was identified in blood plasma, including multiple BRAF mutations in the same patient, clinically relevant BRAF mutations emerging through therapy and co-occurring sub-clonal BRAF and NRAS mutations. The technical validity of this ctDNA analysis was supported by high sample analysis–reanalysis concordance, as well as concordance between different ctDNA measurement technologies. In addition, we observed > 90% concordance in the detection of ctDNA when using cell-stabilising collection tubes followed by 7-day delayed processing, compared with standard EDTA blood collection protocols with rapid processing. We also found that the undetectability of ctDNA at a proportion of treatment cycles was associated with durable clinical benefit (DCB). Conclusion We found that multiple ctDNA processing and analysis methods consistently identified complex longitudinal patterns of clinically relevant mutations, adding support for expanded clinical trials of this technology in a variety of oncology settings.