Patterns of Relative Telomere Length is Associated With hTERT Gene Expression in the Tissue of Patients With Breast Cancer

Association of hTERT expression, Her2Neu, estrogen receptors, progesterone receptors, with telomere length before and at the end of treatment in breast cancer patients

Background

Breast cancer shows significant clinical, morphologic, and molecular variation. Telomeres are nucleoprotein complexes composed of hexanucleotide repeat DNA sequence, TTAGGG, and numerous telomere-associated proteins. The maintenance of telomere length is carried out by a ribonucleoprotein called telomerase, which consists of two main components: a catalytic subunit called hTERT (human telomerase reverse transcriptase) and an RNA template called hTR (human telomerase RNA). The importance of evaluating hTERT expression lies in its potential therapeutic application, being an attractive target due to its almost non-existent expression in normal somatic cells. It is also expected that the anti-neoplastic effect would appear earlier in neoplastic cells with shorter telomeres. Additionally, a significant relationship has been observed between Her2-Neu overexpression and Her2-Neu positivity, which could suggest new combined therapies.The aim of this study was to detect the expression of hTERT, estrogen receptor (ER), progesterone receptor (PR), and HER2-Neu in neoplastic breast tissue embedded in paraffin before treatment and to investigate the relationship between them and with baseline and post-treatment telomere length, as well as with various clinicopathological parameters.

Materials and methods

A cross-sectional-correlational, 21 women diagnosed with breast cancer at the Oncology Service of the High Specialty Medical Unit No. 1 of Bajio of the Mexican Institute of Social Security. The study complies with the Helsinki Declaration and was approved by the Institutional Ethical Committee of the Mexican Institute of Social Security (R-2019-1001-127). A peripheral blood sample was obtained before oncological treatment and at the end of oncological treatment for the measurement of telomere length by extracting DNA from leukocytes, was performed by the quantitative polymerase chain reaction (PCR) method described by Cawthon. Tumor samples were collected from each patient at the oncology department for immunohistochemical determination of biomarker expression (ER, PR, Her2/neu) and hTERT.

Results

Of the 21 cases included in the study, the median age was 57.57 years. Eighteen cases were classified as invasive ductal carcinoma NOS (85.71%), 10 were histologic grade 2 (47.61%), 16 cases were hormone receptor positive (76.19%), 7 were Her2Neu positive (33.33%), and only 2 cases were triple negative (9.52%). Positive hTERT expression was detected in 11 cases (52.38%) and was negative in the remaining cases. A significant association was identified between hTERT-positive cases and Her2-Neu positive cases (p = 0.04). Baseline and post-treatment telomere lengths showed a significant difference using the non-parametric Wilcoxon t-test (p = 0.002). In hTERT-positive cases, there was significant telomere shortening at the end of oncological treatment (6.14 ± 1.54 vs. 4.75 ± 1.96 Kb, p = 0.007).

Conclusion

Positive hTERT immunostaining cases were associated with poor prognostic factors, such as Her2-Neu overexpression and post-treatment telomere shortening. In the future, hTERT immunostaining could be used to select patients for therapies with antagonistic effects on hTERT, as well as in the selection of more appropriate chemotherapy regimens for patients who express it.

Regulation and clinical potential of telomerase reverse transcriptase (TERT/hTERT) in breast cancer

Telomerase reverse transcriptase (TERT/hTERT) serves as the pivotal catalytic subunit of telomerase, a crucial enzyme responsible for telomere maintenance and human genome stability. The high activation of hTERT, observed in over 90% of tumors, plays a significant role in tumor initiation and progression. An in-depth exploration of hTERT activation mechanisms in cancer holds promise for advancing our understanding of the disease and developing more effective treatment strategies. In breast cancer, the expression of hTERT is regulated by epigenetic, transcriptional, post-translational modification mechanisms and DNA variation. Besides its canonical function in telomere maintenance, hTERT exerts non-canonical roles that contribute to disease progression through telomerase-independent mechanisms. This comprehensive review summarizes the regulatory mechanisms governing hTERT in breast cancer and elucidates the functional implications of its activation. Given the overexpression of hTERT in most breast cancer cells, the detection of hTERT and its associated molecules are potential for enhancing early screening and prognostic evaluation of breast cancer. Although still in its early stages, therapeutic approaches targeting hTERT and its regulatory molecules show promise as viable strategies for breast cancer treatment. These methods are also discussed in this paper. Video Abstract.

Fabricating niosomal-PEG nanoparticles co-loaded with metformin and silibinin for effective treatment of human lung cancer cells

Background

Despite current therapies, lung cancer remains a global issue and requires the creation of novel treatment methods. Recent research has shown that biguanides such as metformin (MET) and silibinin (SIL) have a potential anticancer effect. As a consequence, the effectiveness of MET and SIL in combination against lung cancer cells was investigated in this study to develop an effective and novel treatment method.

Methods

Niosomal nanoparticles were synthesized via the thin-film hydration method, and field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FTIR), atomic force microscopy (AFM), and dynamic light scattering (DLS) techniques were used to evaluate their physico-chemical characteristics. The cytotoxic effects of free and drug-loaded nanoparticles (NPs), as well as their combination, on A549 cells were assessed using the MTT assay. An apoptosis test was used while under the influence of medication to identify the molecular mechanisms behind programmed cell death. With the use of a cell cycle test, it was determined whether pharmaceutical effects caused the cell cycle to stop progressing. Additionally, the qRT-PCR technique was used to evaluate the levels of hTERT, BAX, and BCL-2 gene expression after 48-h medication treatment.

Results

In the cytotoxicity assay, the growth of A549 lung cancer cells was inhibited by both MET and SIL. Compared to the individual therapies, the combination of MET and SIL dramatically and synergistically decreased the IC50 values of MET and SIL in lung cancer cells. Furthermore, the combination of MET and SIL produced lower IC50 values and a better anti-proliferative effect on A549 lung cancer cells. Real-time PCR results showed that the expression levels of hTERT and BCL-2 were significantly reduced in lung cancer cell lines treated with MET and SIL compared to single treatments (p< 0.001).

Conclusion

It is anticipated that the use of nano-niosomal-formed MET and SIL would improve lung cancer treatment outcomes and improve the therapeutic efficiency of lung cancer cells.

Triclosan is associated with breast cancer via oxidative stress and relative telomere length

Introduction

Triclosan (TCS), a widely prescribed broad-spectrum antibacterial agent, is an endocrine-disrupting chemical. The relationship and biological mechanisms between TCS exposure and breast cancer (BC) are disputed. We aimed to examine the correlation between urinary TCS exposure and BC risk and estimated the mediating effects of oxidative stress and relative telomere length (RTL) in the above association.

Methods

This case-control study included 302 BC patients and 302 healthy individuals in Wuhan, China. We detected urinary TCS, three common oxidative stress biomarkers [8-hydroxy-2-deoxyguanosine (8-OHdG), 8-iso-prostaglandin F_2α (8-isoPGF_2α), 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA)], and RTL in peripheral blood mononuclear cells.

Results

Significant associations were observed between log-transformed urinary concentrations of TCS, 8-OHdG, HNE-MA, 8-isoPGF_2α, RTL, and BC risk, with the odds ratios (95% confidence intervals) being 1.58 (1.32-1.91), 3.08 (1.55-6.23), 3.39 (2.45-4.77), 3.99 (2.48-6.54), and 1.67 (1.35-2.09), respectively. Continuous TCS exposure was significantly positively correlated with RTL, HNE-MA, and 8-isoPGF_2α (all p<0.05) but not with 8-OHdG (p = 0.060) after adjusting for covariates. The mediated proportions of 8-isoPGF2_2α and RTL in the relationship between TCS and BC risk were 12.84% and 8.95%, respectively (all p<0.001).

Discussion

In conclusion, our study provides epidemiological evidence to confirmed the deleterious effects of TCS on BC and indicated the mediating effect of oxidative stress and RTL on the correlation between TCS and BC risk. Moreover, exploring the contribution of TCS to BC can clarify the biological mechanisms of TCS exposure, provide new clues for the pathogenesis of BC, which is of great significance to improving public health systems.

Relationship between telomere length and the prognosis of breast cancer based on estrogen receptor status: A Mendelian randomization study

Objective

To identify the relationship between telomere length and the prognosis of breast cancer with different status of estrogen receptor (ER).

Methods

We collected single nucleotide polymorphisms (SNPs) associated with telomere length and breast cancer prognosis from the MRCIEU GWAS database and the dataset of a large meta-analysis conducted by the Breast Cancer Association Consortium (BCAC), respectively. The relationship was identified using inverse-variance weighted (IVW), MR-Egger, weighted median, penalized weighted median, and maximum likelihood methods. IVW, MR-Egger, and MR-PRESSO methods were used to perform sensitivity analysis to assess the accuracy of the results.

Results

Telomere length was negatively associated with the prognosis of total breast cancer (odds ratio [OR]=1.84, 95% confidence interval [CI]=1.08-3.14, IVW method), especially with ER- breast cancer (OR=1.89, 95% CI=1.11-3.22, IVW method). No similar relationship was found between telomere length and the prognosis of ER+ breast cancer (OR=0.99, 95% CI=0.62-1.58, IVW method). The findings from other methods were consistent with the results shown by the IVW method. The Mendelian randomization assumptions did not appear to be violated. Sensitivity analysis indicated that the result was robust, and no bias was observed in the study.

Conclusion

Telomere length is associated with the prognosis of total breast cancer, especially with ER- breast cancer. There is no significant correlation between telomere length and the prognosis of ER+ breast cancer. These findings add to the evidence that long telomere could predict a poor prognosis of ER- breast cancer.

Telomere length in peripheral blood lymphocytes related to genetic variation in telomerase, prognosis and clinicopathological features in breast cancer patients

Disruption of telomere length (TL) homeostasis in peripheral blood lymphocytes has been previously assessed as a potential biomarker of breast cancer (BC) risk. The present study addressed the relationship between lymphocyte TL (LTL), prognosis and clinicopathological features in the BC patients since these associations are insufficiently explored at present. LTL was measured in 611 BC patients and 154 healthy controls using the monochrome multiplex quantitative Polymerase Chain Reaction assay. In addition, we genotyped nine TL-associated single-nucleotide polymorphisms that had been identified through genome-wide association studies. Our results showed that the patients had significantly (P = 0.001, Mann-Whitney U-test) longer LTL [median (interquartile range); 1.48 (1.22-1.78)] than the healthy controls [1.27 (0.97-1.82)]. Patients homozygous (CC) for the common allele of hTERT rs2736108 or the variant allele (CC) of hTERC rs16847897 had longer LTL. The latter association remained statistically significant in the recessive genetic model after the Bonferroni correction (P = 0.004, Wilcoxon two-sample test). We observed no association between LTL and overall survival or relapse-free survival of the patients. LTL did not correlate with cancer staging based on Union for International Cancer Control (UICC), The tumor node metastasis (TNM) staging system classification, tumour grade or molecular BC subtypes. Overall, we observed an association between long LTL and BC disease and an association of the hTERC rs16847897 CC genotype with increased LTL. However, no association between LTL, clinicopathological features and survival of the patients was found.

TZAP Mutation Leads to Poor Prognosis of Patients with Breast Cancer †

Background and Objectives: ZBTB48 is a telomere-associated factor that has been renamed as telomeric zinc finger-associated protein (TZAP). It binds preferentially to long telomeres, competing with telomeric repeat factors 1 and 2. Materials and Methods: We analyzed the TZAP mutation in 128 breast carcinomas (BCs). In addition, its association with telomere length was investigated. Results: The TZAP mutation (c.1272 G > A, L424L) was found in 7.8% (10/128) of the BCs and was associated with the N0 stage. BCs with the TZAP mutation had longer telomeres than those without this mutation. Survival analysis showed that the TZAP mutation resulted in poorer overall survival. Conclusions: These results suggest that the TZAP mutation is a possible prognostic marker in BC.