Association of SIPA1 545 C > T polymorphism with survival in Chinese women with metastatic breast cancer

A novel transcription factor SIPA1: identification and verification in triple-negative breast cancer

Transcription factors (TFs) regulate the expression of genes responsible for cell growth, differentiation, and responses to environmental factors. In this study, we demonstrated that signal-induced proliferation-associated 1 (SIPA1), known as a Rap-GTPase-activating protein, bound DNA and served as a TF. Importin β1 was found to interact with SIPA1 upon fibronectin treatment. A TGAGTCAB motif was recognized and bound by DNA-binding region (DBR) of SIPA1, which was confirmed by electrophoretic mobility shift assay. SIPA1 regulated the transcription of multiple genes responsible for signal transduction, DNA synthesis, cell adhesion, cell migration, and so on. Transcription of fibronectin 1, which is crucial for cell junction and migration of triple-negative breast cancer (TNBC) cells, was regulated by SIPA1 in a DBR-dependent manner both in vivo and in vitro. Furthermore, single-cell transcriptome sequencing analysis of specimens from a metastatic TNBC patient revealed that SIPA1 was highly expressed in metastatic TNBC. Hence, this study demonstrated that SIPA1 served as a TF, promoting TNBC migration, invasion, and metastasis.

The role of SIPA1 in the development of cancer and metastases (Review)

Cancer is a leading cause of mortality and the majority of deaths are due to metastases. Many molecules have been implicated in the development of metastases. Signal induced proliferation associated protein 1 (SIPA1), a mitogen-inducible gene, has been demonstrated to be involved in the metastasis of various solid tumours and may indicate a poor prognosis. Polymorphisms of SIPA1 can be associated with several different types of cancer and interactions between SIPA1 and binding molecules integrate a series of cellular functions, which may promote the development and metastasis of cancer. The mechanisms by which SIPA1 promotes the development and metastasis of cancer varies among tumour types. The present review describes the structure, function and regulation of SIPA1 and focuses on its role in cancer metastasis. Possibilities for future research and the clinical application of SIPA1 are also discussed.

Genetic insights into the morass of metastatic heterogeneity

Tumour heterogeneity poses a substantial problem for the clinical management of cancer. Somatic evolution of the cancer genome results in genetically distinct subclones in the primary tumour with different biological properties and therapeutic sensitivities. The problem of heterogeneity is compounded in metastatic disease owing to the complexity of the metastatic process and the multiple biological hurdles that the tumour cell must overcome to establish a clinically overt metastatic lesion. New advances in sequencing technology and clinical sample acquisition are providing insights into the phylogenetic relationship of metastases and primary tumours at the level of somatic tumour genetics while also illuminating fundamental mechanisms of the metastatic process. In addition to somatically acquired genetic heterogeneity in the tumour cells, inherited population-based genetic heterogeneity can profoundly modify metastatic biology and further complicate the development of effective, broadly applicable antimetastatic therapies. Here, we examine how genetic heterogeneity impacts metastatic disease and the implications of current knowledge for future research endeavours and therapeutic interventions.

The contribution of SIPA1 and RRP1B germline polymorphisms to breast cancer phenotype, lymph node status and survival in a group of Lithuanian young breast cancer patients

The germline polymorphisms in signal-inducing proliferation-associated protein 1 (SIPA1) and ribosomal RNR processing 1B (RRP1B) might be involved in breast cancer metastasis. The aim of this study was to analyze how SIPA1 and RRP1B polymorphisms contribute to breast cancer phenotype, lymph node status and survival. A group of 100 young, I-II stage breast cancer patients were analyzed for SIPA1 and RRP1B polymorphisms with PCR-RFLP assay. SIPA1 c.2760G > A, c.545C > T and RRP1B c.436T > C polymorphisms were associated with lymph node status, survival and tumor grade, respectively. Our results suggest that SIPA1 and RRP1B germline polymorphisms are important for breast cancer prognosis.

The role of individual inheritance in tumor progression and metastasis

Metastasis, the dissemination and growth of tumor cells at secondary sites, is the primary cause of patient mortality from solid tumors. Metastasis is an extremely complex, inefficient process requiring contributions of not only the tumor cell but also local and distant environmental factors, at both the cellular and molecular level. Variation in the function of any of the steps in the metastatic cascade may therefore have profound implications for the ultimate course of the disease. In addition to the somatic and cellular heterogeneity that can affect cancer outcome, an individual's specific ancestry or genetic background can also significantly influence metastatic progression. These inherited variants not only encoded for metastatic susceptibility but also provided a window to study critical factors that are not easily accessible with current technologies. Furthermore, investigations into inherited metastatic susceptibility enable identification of important molecular and cellular processes that are not subject to mutation and are consequently not detectable by standard cancer genome sequencing strategies. Incorporation of inherited variation into metastasis research therefore provides methods to more comprehensively investigate the etiology of the lethal consequences of tumor progression.

Common germline polymorphisms associated with breast cancer-specific survival

INTRODUCTION

Previous studies have identified common germline variants nominally associated with breast cancer survival. These associations have not been widely replicated in further studies. The purpose of this study was to evaluate the association of previously reported SNPs with breast cancer-specific survival using data from a pooled analysis of eight breast cancer survival genome-wide association studies (GWAS) from the Breast Cancer Association Consortium.

METHODS

A literature review was conducted of all previously published associations between common germline variants and three survival outcomes: breast cancer-specific survival, overall survival and disease-free survival. All associations that reached the nominal significance level of P value <0.05 were included. Single nucleotide polymorphisms that had been previously reported as nominally associated with at least one survival outcome were evaluated in the pooled analysis of over 37,000 breast cancer cases for association with breast cancer-specific survival. Previous associations were evaluated using a one-sided test based on the reported direction of effect.

RESULTS

Fifty-six variants from 45 previous publications were evaluated in the meta-analysis. Fifty-four of these were evaluated in the full set of 37,954 breast cancer cases with 2,900 events and the two additional variants were evaluated in a reduced sample size of 30,000 samples in order to ensure independence from the previously published studies. Five variants reached nominal significance (P <0.05) in the pooled GWAS data compared to 2.8 expected under the null hypothesis. Seven additional variants were associated (P <0.05) with ER-positive disease.

CONCLUSIONS

Although no variants reached genome-wide significance (P <5 x 10(-8)), these results suggest that there is some evidence of association between candidate common germline variants and breast cancer prognosis. Larger studies from multinational collaborations are necessary to increase the power to detect associations, between common variants and prognosis, at more stringent significance levels.

The SIPA1 -313A>G polymorphism is associated with prognosis in inoperable non-small cell lung cancer

Polymorphism in signal-induced proliferation-associated 1 (SIPA1) gene may contribute to the development of metastasis in human cancers. In this preliminary study, we examined the association of the SIPA1 -313A>G (rs931127) polymorphism with overall survival (OS) and progression-free survival (PFS) in 351 inoperable patients with non-small cell lung cancer (NSCLC) treated with radiotherapy or radiochemotherapy (curative or palliative). The GG homozygotes had significantly shorter PFS under codominant and recessive models in all patients (hazard ratio (HR) 1.47, p = 0.035, and HR 1.47, p = 0.022, respectively) and in advanced stage subgroup (HR 1.49, p = 0.037, and HR 1.48, p = 0.023, respectively). The GG genotype was also associated with reduced OS and PFS (codominant model: HR 2.41, p = 0.020, and HR 2.34, p = 0.020, respectively; recessive model: HR 2.16, p = 0.026, and HR 2.18, p = 0.022, respectively) in radiotherapy alone subgroup. Moreover, the SIPA1 -313GG was identified as an independent adverse prognostic factor for PFS in the cohort. Our results indicate, for the first time, that the SIPA1 -313A>G may have a prognostic role in unresected NSCLC making it a potential predictor of poor survival due to earlier progression.

The association of SIPA1 gene polymorphisms with breast cancer risk: evidence from published studies

Previous studies have focused on the association of signal-induced proliferation associated 1 gene (SIPA1) with carcinogenesis of many cancers, including breast cancer. It has been suggested that SIPA1 polymorphisms are associated with susceptibility to breast cancer. In the present study, we performed a meta-analysis to systematically summarize the possible association between SIPA1 and the risk for breast cancer. We conducted a search of case-control studies on the associations of SPIA1 with susceptibility to breast cancer in PubMed, Embase, International Statistical Institute Web of Science, Wanfang Database in China, and Chinese National Knowledge Infrastructure databases. Data from eligible studies were extracted for meta-analysis. Breast cancer risk associated with SIPA1 was estimated by pooled odds ratios and 95% confidence intervals. Four studies on SIPA1 and breast cancer were included in our meta-analysis. Our results showed that rs746429 was associated with the risk of breast cancer. However, rs931127 and rs3741378 were not found to be associated with breast cancer in our analysis. This meta-analysis suggests that rs746429 is associated with the risk of breast cancer. Well-designed studies with larger sample size and more ethnic groups are required to further validate the results.

Use of pharmacogenetics for predicting cancer prognosis and treatment exposure, response and toxicity

Cancer treatment is complicated because of a multitude of treatment options and little patient-specific information to help clinicians choose appropriate therapy. There are two genomes relevant in cancer treatment: the tumor (somatic) and the patient (germline). Together, these two genomes dictate treatment outcome through four processes: the somatic genome primarily determines tumor prognosis and response while the germline genome modulates treatment exposure and toxicity. In this review, we describe the influence of these genomes on treatment outcomes by highlighting examples of genetic variation that are predictors of each of these four factors, prognosis, response, toxicity and exposure, and discuss the translation and clinical implementation of each. Use of pre-treatment pharmacogenetic testing will someday enable clinicians to make individualized therapy decisions about aggressiveness, drug selection and dose, improving treatment outcomes for cancer patients.