Oxaliplatin regulates DNA repair responding to ionizing radiation and enhances radiosensitivity of human cervical cancer cells

Silencing of STEAP3 suppresses cervical cancer cell proliferation and migration via JAK/STAT3 signaling pathway

BACKGROUND

Six-transmembrane epithelial antigen of prostate 3 (STEAP3), an essential constituent of the STEAP family protein, plays a notable role in promoting cancer proliferation and metastasis. Despite the importance of the STEAP gene family in tumor progression, the function of STEAP3 in cervical cancer (CC) remains unclear.

MATERIALS AND METHODS

The expression of STEAP3 protein in CC tissues and cell lines was identified using immunohistochemistry. The Reduced Representation Bisulfite Sequencing (RRBS) was used to detect global gene DNA methylation in CC tissues and paracancerous tissues. Cell viability, proliferation, migration, and invasion, were evaluated using the Cell Counting Kit-8 (CCK8), 5-ethynyl-2'-deoxyuridine (EdU), wound repair assay, and transwell assay, respectively. RNA sequencing was applied to explore STEAP3-related signaling pathways. Western blotting was performed to detect the expression of related proteins, including epithelial-mesenchymal transition (EMT) and Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling markers.

RESULTS

Herein, STEAP3 was strongly expressed in CC tissues and associated with poor prognosis. CC samples exhibited lower levels of STEAP3 methylation than normal samples, and the methylation levels of CpG islands in STEAP3 were association with prognosis. In contrast to control group, STEAP3 knockdown suppressed the proliferation and invasion of CC cells and enhanced sensitivity to oxaliplatin. Silencing of STEAP3 led to reduced N-cadherin and vimentin levels and increased E-cadherin expression. RNA sequencing analysis suggested that STEAP3 mediated the activation of the JAK STAT3 signaling pathway. Additionally, inhibition of STEAP3 decreased the phosphorylation of JAK2 and STAT3. Interestingly, colivelin (a STAT3 activator) modified STEAP3-induced cell proliferation, invasion, and expression of related proteins in the EMT and JAK/STAT3 signaling pathway.

CONCLUSION

STEAP3 was significantly associated with CC progression mediated via the JAK/STAT3 signaling pathway and may serve as an effective therapeutic target.

SHP-2 restricts apoptosis induced by chemotherapeutic agents via Parkin-dependent autophagy in cervical cancer

Background

Autophagy is a cell degradation pathway that eliminates damaged or unwanted proteins and organelles. Autophagy protects cells from chemotherapeutic agents by scavenging damaged mitochondria.

Methods

Plasmid transfection and shRNA were used to regulate SHP-2 expression. Annexin V/PI staining were employed to analysis apoptosis. Flow cytometry was used to analyse intracellular calcium level and ROS. Immunofluorescence was used to detect mitochondria membrane potential, autophagy and Parkin translocation.

Results

In cervical cancer, we found that SHP-2 suppressed apoptosis induced by Oxaliplatin and 5-FU. Further studies have found that SHP-2 protects against mitochondrial damage. This role of SHP-2 is associated with the activation of autophagy. In addition, SHP-2 degraded impaired mitochondria dependent on the ubiquitin ligase function of Parkin.

Conclusions

These results suggest that SHP-2 inhibits the apoptosis induced by chemotherapeutic drugs through activating autophagy to degrade damaged mitochondria and ubiquitin ligase Parkin involved in SHP-2 induced autophagy.

Aldo-keto reductase 1C3 may be a new radioresistance marker in non-small-cell lung cancer

Human aldo-keto reductase 1C3, type 2 3α-hydroxysteroid dehydrogenase (HSD)/type 5 17β-HSD (AKR1C3) is known to be involved in steroid, prostaglandin and lipid aldehyde metabolism. The role of AKR1C3 in the radiosensitivity to X-rays of human non-small-cell lung cancer (NSCLC) cells was explored. In this study, a specific small interfering RNA (siRNA) to target the AKR1C3 gene was used. A suite of readouts including cell survival were determined using a colony formation assay; apoptosis evaluated by Annexin V expression levels, irradiation-induced cytotoxicity established using a MTT cell viability assay and cell cycle distribution measured by flow cytometry were used in characterizing the role of the AKR1C3 gene. Although AKR1C3 was significantly overexpressed in both our radioresistant subclone cells and NSCLC tissues, a specific AKR1C3 siRNA significantly enhanced cell radiosensitivity and was concomitant with decreased expression of this gene. Furthermore, reduced interleukin-6 (IL-6)-mediated radioresistance was observed when siRNA was used to knock down AKR1C3 activity. This AKR1C3-mediated radioresistance was correlated with an arrest in the G2/M cell cycle and a decreased induction of apoptosis. AKR1C3 may present a potential therapeutic target in addressing radioresistance of NSCLC, and in particular in IL-6-mediated radioresistance.

Selective radiosensitization of human cervical cancer cells and normal cells by artemisinin through the abrogation of radiation-induced G2 block

OBJECTIVE

Artemisinin has been shown to inhibit the growth of some human cancer cells. In this study, we investigated the radiosensitizing effects of artemisinin on cervical cancer cells and normal human fibroblast cells and also assessed some possible mechanisms for these effects.

MATERIALS AND METHODS

Two cervical cancer cell lines, HeLa and SiHa cells, and GM0639 normal human fibroblast cell line were treated with various concentrations of artemisinin plus radiation; the cell viability was tested using both 3-(4,5-dimethylthiazolyl-2-y1)-2, 5-diphenyltetrazolium bromide and clonogenic assays. Radiation dose-modifying factors were measured by clonogenic survival assay. Annexin V/propidium iodide assay for the evaluation of apoptosis and cell cycle phase were determined by flow cytometry, and the expression of the cell cycle-associated proteins Wee 1 and cyclin B1 were analyzed by Western blot analysis.

RESULTS

Artemisinin showed higher cytotoxicity in cervical cancer cell lines, especially in SiHa cells, than in the normal cell line. In both clonogenic assay and apoptosis, artemisinin sensitized the HeLa cancer cells to the cytotoxicity of radiation, yielding a dose-modifying factor of 1.24, but not SiHa cancer cells and GM normal cells. At a dose of 110 nmol/L, artemisinin did not change the distribution of cell cycle in 3 tested cell lines, but artemisinin abrogated the radiation-induced G2 blockade. Analyses of G2-checkpoint-related proteins, the activation of Wee 1 and depression of cyclin B1 expression induced by radiation, could be restored to the control level by artemisinin.

CONCLUSIONS

Given the unique cytotoxic profile of artemisinin on cancer cells and normal cells, artemisinin may be a potentially promising radiosensitizer through the regulation of the expression of G2 checkpoint-related proteins like Wee 1 and cyclin B1, and improve therapeutic ratios for the combination of artemisinin and ionizing irradiation in the treatment of patients with cervical cancer.

Expression of phosphorylated histone H2AX (γ-H2AX) in normal and neoplastic squamous epithelia of the uterine cervix: an immunohistochemical study with epidermal growth factor receptor

The histone γ-H2AX is a marker of activated DNA damage and is overexpressed in different cancers and their precursor lesions, indicating a role in oncogenic transformation. Epidermal growth factor receptor (EGFR) is overexpressed in many kinds of epithelial neoplasms. This study aimed to determine whether immunohistochemical expression of γ-H2AX is involved in the progression of the morphological spectrum from normal squamous cervical epithelia (NE, n=33) to cervical intraepithelial neoplasia (CIN; CIN1, n=9; CIN2/3, n=33) and cervical invasive squamous cell carcinoma (ISCC, n=33), whether γ-H2AX expression follows the pattern of proliferation of atypical squamous cells as shown by EGFR immunoreactivity, and whether it is correlated with clinicopathologic variables in ISCC. Immunostaining for both the factors was scored semiquantitatively for moderate and strong intensities. Gamma-H2AX and EGFR expression, respectively, increased from NE and CIN1 to CIN2/3 and ISCCs significantly (P=0.0001, respectively). Gamma-H2AX reactivity was found in the nuclei of the cells of the upper epithelial levels and the cells of basal/parabasal type in variable quantities in NE and CIN; expression of γ-H2AX was seen in the nuclei of ISCC including keratinizing cells in horn pearls. EGFR staining was mainly membranous and noted in basal/parabasal cells in NE and atypically proliferating keratinocytes in CIN and nonkeratinizing cells of ISCC. In addition, immature squamous metaplasias were decorated by the antibodies used. Immunoscores for γ-H2AX and EGFR, respectively, did not differ between International Federation of Gynecology and Obstetrics stages I and II, keratinizing and nonkeratinizing ISCC, and CIN2/3 and ISCC. However, expression patterns were different for both the factors, suggesting their involvement in different biological mechanisms, with regard to γ-H2AX apart from proliferation. Overexpression of γ-H2AX in CIN2/3 and ISCC of the uterine cervix reflects the neoplastic transformation of cervical squamous epithelia in reaction to increased DNA-damage and supports the classification of dysplasia into low-grade squamous intraepithelial lesions and high-grade squamous intraepithelial lesions.

Differential gene expression profiles of radioresistant non-small-cell lung cancer cell lines established by fractionated irradiation: tumor protein p53-inducible protein 3 confers sensitivity to ionizing radiation

PURPOSE

Despite the widespread use of radiotherapy as a local and regional modality for the treatment of cancer, some non-small-cell lung cancers commonly develop resistance to radiation. We thus sought to clarify the molecular mechanisms underlying resistance to radiation.

METHODS AND MATERIALS

We established the radioresistant cell line H460R from radiosensitive parental H460 cells. To identify the radioresistance-related genes, we performed microarray analysis and selected several candidate genes.

RESULTS

Clonogenic and MTT assays showed that H460R was 10-fold more resistant to radiation than H460. Microarray analysis indicated that the expression levels of 1,463 genes were altered more than 1.5-fold in H460R compared with parental H460. To evaluate the putative functional role, we selected one interesting gene tumor protein p53-inducible protein 3 (TP53I3), because that this gene was significantly downregulated in radioresistant H460R cells and that it was predicted to link p53-dependent cell death signaling. Interestingly, messenger ribonucleic acid expression of TP53I3 differed in X-ray-irradiated H460 and H460R cells, and overexpression of TP53I3 significantly affected the cellular radiosensitivity of H460R cells.

CONCLUSIONS

These results show that H460R may be useful in searching for candidate genes that are responsible for radioresistance and elucidating the molecular mechanism of radioresistance.