Reduced tumor vessel density and high expression of glucose transporter 1 suggest tumor hypoxia of squamous cell carcinoma of the esophagus surviving after radiotherapy

Optical imaging technology realizes early tumor diagnosis by detecting angiogenesis

The occurrence and development of blood vessels play a key role in different stages of tumor growth, while current imaging techniques are difficult to detect early tumor angiogenesis because of their low sensitivity. Therefore, this article introduces high-sensitivity optical imaging technology to achieve early tumor diagnosis by detecting tumor angiogenesis. Liver and pancreatic tumor models in nude mice were respectively established to represent tumors with a rich or poor blood supply. The two optical imaging methods, in vivo confocal fluorescence imaging and photoacoustic imaging, were used to detect tumor angiogenesis at different stages. Finally, the changes in blood vessels were verified by immunostaining. Both autoluminescence imaging and pathological staining confirmed that these two tumor models were successfully established. In vivo confocal fluorescence imaging found that the early tumor blood vessel structure had obvious characteristics: disorder, tortuous deformation, thin diameter, which were significantly different from the normal tissues. Photoacoustic imaging could effectively identify blood vessels inside early tumors, which were small and disordered and might be used as one of the predictors of early tumor development. CD31 immunostaining was used to evaluate the vascular status of tumors at different stages and under different blood supply conditions. The vascular structures observed under the microscope in the two tumor models were consistent with the results observed by optical imaging methods. The optical imaging methods could monitor the characteristics of angiogenesis in the rich or poor blood supply tumors, especially the early diagnosis of tumors.

Increased glucose influx and glycogenesis in lung cancer cells surviving after irradiation

PURPOSE

Lung cancer is considered as one of the most frequent malignancies worldwide. Radiotherapy is the main treatment modality applied for locally advanced disease, but remnant surviving cancer tissue results in disease progression in the majority of irradiated lung carcinomas. Metabolic reprogramming is regarded as a cancer hallmark and is associated with resistance to radiation therapy. Here, we explored metabolic alterations possibly related to cancer cell radioresistance.

MATERIALS AND METHODS

We compared the expression of metabolism-related enzymes in the parental A549 lung cancer cell line along with two new cell lines derived from A549 cells after recovery from three (A549-IR3) and six (A549-IR6) irradiation doses with 4 Gy. Differential GLUT1 and GYS1 expression on proliferation and radioresistance were also comparatively investigated.

RESULTS

A549-IR cells displayed increased extracellular glucose absorption, and enhanced mRNA and protein levels of the GLUT1 glucose transporter. GLUT1 inhibition with BAY-876, suppressed cell proliferation and the effect was significantly more profound on A549-IR3 cells. Protein levels of molecules associated with aerobic or anaerobic glycolysis, or the phosphate pentose pathway were similar in all three cell lines. However, glycogen synthase 1 (GYS1) was upregulated, especially in the A549-IR3 cell line, suggestive of glycogen accumulation in cells surviving post irradiation. GYS1-gene silencing repressed the proliferation capacity of A549, but this increased their radioresistance. The radio-protective effect of the suppression of proliferative activity induced by GYS1 silencing did not protect A549-IR3 cells against further irradiation.

CONCLUSIONS

These findings indicate that GYS1 activity is a critical component of the metabolism of lung cancer cells surviving after fractionated radiotherapy. Targeting the glycogen metabolic reprogramming after irradiation may be a valuable approach to pursue eradication of the post-radiotherapy remnant of disease.

Recent progress of the tumor microenvironmental metabolism in cervical cancer radioresistance

Radiotherapy is widely used as an indispensable treatment option for cervical cancer patients. However, radioresistance always occurs and has become a big obstacle to treatment efficacy. The reason for radioresistance is mainly attributed to the high repair ability of tumor cells that overcome the DNA damage caused by radiotherapy, and the increased self-healing ability of cancer stem cells (CSCs). Accumulating findings have demonstrated that the tumor microenvironment (TME) is closely related to cervical cancer radioresistance in many aspects, especially in the metabolic processes. In this review, we discuss radiotherapy in cervical cancer radioresistance, and focus on recent research progress of the TME metabolism that affects radioresistance in cervical cancer. Understanding the mechanism of metabolism in cervical cancer radioresistance may help identify useful therapeutic targets for developing novel therapy, overcome radioresistance and improve the efficacy of radiotherapy in clinics and quality of life of patients.

Aberrant GLUT1 Expression Is Associated With Carcinogenesis and Progression of Liver Fluke-associated Cholangiocarcinoma

BACKGROUND/AIM

Glucose transporter 1 (GLUT1) has been demonstrated to be overexpressed in various cancer tissues and play a significant role on growth, metastasis, and apoptosis in cancer cells. This study aimed to reveal the clinical relevance of glucose transporter 1 (GLUT1) in carcinogenesis and progression on liver fluke-associated cholangiocarcinoma (CCA).

MATERIALS AND METHODS

Expression of GLUT1 in CCA tissues from patients, as well as from a liver fluke-induced CCA hamster model, was determined using immunohistochemistry. CCA cell lines were transfected with GLUT1 siRNA and the roles of GLUT1 on cell growth as well as migration and invasion were investigated by using a clonogenic assay and Boyden chamber assays, respectively.

RESULTS

GLUT1 was aberrantly expressed in hyperplastic/dysplastic bile ducts and CCA, but not in the normal bile ducts. High GLUT1 expression was significantly associated with non-papillary type, large tumor size, and short survival of patients. GLUT1 was expressed during cholangio-carcinogenesis and gradually increased with progression of histopathologic bile ducts. Silencing of GLUT1 expression significantly suppressed growth, migration, and invasion of CCA cell lines.

CONCLUSION

GLUT1 plays important roles in carcinogenesis and progression of liver fluke-associated CCA. Targeting GLUT1 may be a strategy for treatment of metastasis in liver fluke-associated CCA.

Effect of combination of curcumin and GLUT-1 AS-ODN on radiosensitivity of laryngeal carcinoma through regulating autophagy

BACKGROUND

This study is to explore the role of curcumin and GLUT-1 antisense oligodeoxynucleotides (AS-ODN) on autophagy modulation-initiated radiosensitivity.

METHODS

BALB/c mice were employed to establish xenograft model using Tu212 cell. The expression of autophagy- and apoptosis-related proteins was determined by WB. Autophagosome was observed under transmission electron microscope. Apoptosis of tumor tissue were detected by TUNEL staining.

RESULTS

Combinations of curcumin and GLUT-1 AS-ODN with 10 Gy inhibited the tumor growth by inducing apoptosis of laryngeal cancer cells followed with the enhancement of autophagy. 3-MA also had a promotion effect on irradiation-mediated growth inhibition possibly by depressing PI3K and on curcumin/GLUT-1 AS-ODN-mediated growth inhibition potentially by regulating autophagic events. Of note, a de-escalation of radiotherapy dose (5 Gy) along with curcumin, GLUT-1 AS-ODN or 3-MA produced a stronger effect than high dosage of radiotherapy (10 Gy) alone.

CONCLUSIONS

Curcumin and GLUT-1 AS-ODN improve the radiosensitivity of laryngeal carcinoma through regulating autophagy and inducing apoptosis.

Co-Inhibition of GLUT-1 Expression and the PI3K/Akt Signaling Pathway to Enhance the Radiosensitivity of Laryngeal Carcinoma Xenografts In Vivo

In the present study, we investigated the role of GLUT-1 and PI3K/Akt signaling in radioresistance of laryngeal carcinoma xenografts. Volume, weight, radiosensitization, and the rate of inhibition of tumor growth in the xenografts were evaluated in different groups. Apoptosis was evaluated by TUNEL assay. In addition, mRNA and protein levels of GLUT-1, p-Akt, and PI3K in the xenografts were measured. Treatment with LY294002, wortmannin, wortmannin plus GLUT-1 AS-ODN, and LY294002 plus GLUT-1 AS-ODN after X-ray irradiation significantly reduced the size and weight of the tumors, rate of tumor growth, and apoptosis in tumors compared to that observed in the 10-Gy group (p<0.05). In addition, mRNA and protein expression of GLUT-1, p-Akt, and PI3K was downregulated. The E/O values of LY294002, LY294002 plus GLUT-1 AS-ODN, wortmannin, and wortmannin plus GLUT-1 AS-ODN were 2.7, 1.1, 1.8, and 1.8, respectively. Taken together, these data indicate that GLUT-1 AS-ODN as well as the inhibitors of PI3K/Akt signaling may act as radiosensitizers of laryngeal carcinoma in vivo.

Inhibiting GLUT-1 expression and PI3K/Akt signaling using apigenin improves the radiosensitivity of laryngeal carcinoma in vivo

Hypoxia is an important factor in radioresistance of laryngeal carcinoma. Glucose transporter-1 (GLUT-1) is an important hypoxic marker in malignant tumors, including laryngeal carcinoma. Apigenin is a natural phytoestrogen flavonoid that has potential anticancer effects. Various studies have reported that the effects of apigenin on lowering GLUT-1 expression were involved in downregulation of the PI3K/Akt pathway. Thus, apigenin may improve the radiosensitivity of laryngeal carcinoma by suppressing the expression of GLUT-1 via the PI3K/Akt pathway. The effect of GLUT-1 and PI3K/Akt pathway-related factor expressions by apigenin or antisense oligonucleotides (AS-ODNs) on the radiosensitivity of laryngeal carcinoma in vivo was assessed. The xenograft volume, xenograft weight and apoptosis detection were performed to determine radiosensitivity. The results showed that apigenin or apigenin plus GLUT-1 AS-ODNs improved the radiosensitivity of xenografts. Apigenin or apigenin plus GLUT-1 reduced the expression of GLUT-1, Akt, and PI3K mRNA after X-ray radiation. We found similar results at the protein level. The results suggest that the effects of apigenin on inhibiting xenograft growth and enhancing xenograft radiosensitivity may be associated with suppressing the expression of GLUT-1 via the PI3K/Akt pathway. In addition, apigenin may enhance the effects of GLUT-1 AS-ODNs via the same mechanism.

Ion channel expression as promising cancer biomarker

Cancer is a disease with marked heterogeneity in both response to therapy and survival. Clinical and histopathological characteristics have long determined prognosis and therapy. The introduction of molecular diagnostics has heralded an explosion in new prognostic factors. Overall, histopathology, immunohistochemistry and molecular biology techniques have described important new prognostic subgroups in the different cancer categories. Ion channels and transporters (ICT) are a new class of membrane proteins which are aberrantly expressed in several types of human cancers. Besides regulating different aspect of cancer cell behavior, ICT can now represent novel cancer biomarkers. A summary of the data obtained so far and relative to breast, prostate, lung, colorectal, esophagus, pancreatic and gastric cancers are reported. Special emphasis is given to those studies aimed at relating specific ICT or a peculiar ICT profile with current diagnostic methods. Overall, we are close to exploit ICTs for diagnostic, prognostic or predictive purposes in cancer. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

Roles of glucose transporter-1 and the phosphatidylinositol 3‑kinase/protein kinase B pathway in cancer radioresistance (review)

The mechanisms underlying cancer radioresistance remain unclear. Several studies have found that increased glucose transporter‑1 (GLUT‑1) expression is associated with radioresistance. Recently, the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway was reported to be involved in the control of GLUT‑1 trafficking and activity. Activation of the PI3K/Akt pathway may itself be associated with cancer radioresistance. Thus, increasing attention has been devoted to the effects of modifying the expression of GLUT‑1 and the PI3K/Akt pathway on the increase in the radiosensitivity of cancer cells. This review discusses the importance of the association between elevated expression of GLUT‑1 and activation of the PI3K/Akt pathway in the development of radioresistance in cancer.

Anticancer mechanism of apigenin and the implications of GLUT-1 expression in head and neck cancers

Apigenin, a natural phytoestrogen flavonoid, has potential biological effects, including antioxidative, anti-inflammatory and anticancer activities. The mechanisms of anticancer activities of apigenin are unknown. Some studies have found that apigenin inhibits GLUT-1 mRNA and protein expression in cancer cells. Thus, we hypothesized that apigenin exerts similar effects on head and neck cancers through its inhibition of GLUT-1 expression. In this article, we review the anticancer mechanism of apigenin and the implications of GLUT-1 expression in head and neck cancers. In addition, we describe the current state of knowledge about the relationship between apigenin and GLUT-1 expression in head and neck cancers.

Effect of antisense oligodeoxynucleotides glucose transporter-1 on enhancement of radiosensitivity of laryngeal carcinoma

PURPOSE

Laryngeal carcinomas always resist to radiotherapy. Hypoxia is an important factor in radioresistance of laryngeal carcinoma. Glucose transporter-1 (GLUT-1) is considered to be a possible intrinsic marker of hypoxia in malignant tumors. We speculated that the inhibition of GLUT-1 expression might improve the radiosensitivity of laryngeal carcinoma.

METHODS

We assessed the effect of GLUT-1 expression on radioresistance of laryngeal carcinoma and the effect of GLUT-1 expressions by antisense oligodeoxynucleotides (AS-ODNs) on the radiosensitivity of laryngeal carcinoma in vitro and in vivo.

RESULTS

After transfection of GLUT-1 AS-ODNs: MTS assay showed the survival rates of radiation groups were reduced with the prolongation of culture time (p<0.05); Cell survival rates were significantly reduced along with the increasing of radiation dose (p<0.05). There was significant difference in the expression of GLUT-1mRNA and protein in the same X-ray dose between before and after X-ray radiation (p<0.05). In vivo, the expressions of GLUT-1 mRNA and protein after 8Gy radiation plus transfection of GLUT-1 AS-ODNs were significant decreased compared to 8Gy radiation alone (p<0.001).

CONCLUSION

Radioresistance of laryngeal carcinoma may be associated with increased expression of GLUT-1 mRNA and protein. GLUT-1 AS-ODNs may enhance the radiosensitivity of laryngeal carcinoma mainly by inhibiting the expression of GLUT-1.

Quantitative measurement of contrast enhancement of esophageal squamous cell carcinoma on clinical MDCT

AIM

To investigate contrast-enhanced computed tomography (CECT) for discriminating esophageal squamous cell carcinoma (ESCC) from normal esophagus and evaluating outcomes within tumors after chemoradiotherapy (CRT).

METHODS

Sixty-four patients with surgical ESCC served as group A, and underwent thoracic contrast-enhanced scan with 16-section multidetector row CT 1 wk before surgery. Thirty-five patients with advanced ESCC receiving 4-wk CRT and showing response to CRT served as group B, and underwent CT scans similar with group A 4 wk after completion of CRT. In group A, differences in CT attenuation values (in HU) between the preoperative ESCC and background normal esophageal wall (delta CT(1)), or between different background normal esophageal walls (delta CT(2)) were compared. Furthermore, delta CT(1) between group A and B was also compared.

RESULTS

In group A, mean delta CT(1) was higher than delta CT(2) (23.86 ± 10.59 HU vs 6.24 ± 3.06 HU, P < 0.05). When a delta CT(1) of 10.025 HU was employed at a cut-off value to discriminate ESCC from normal esophagus, a sensitivity of 89.1% and specificity of 90.6% were achieved. Mean delta CT(1) was lower in group B than in group A (9.25 ± 10.86 vs 23.86 ± 10.59, P < 0.05), and a delta CT(1) of 15.45 HU was obtained at a cut-off value to assess the CRT changes with a sensitivity of 76.6% and specificity of 77.1%.

CONCLUSION

CECT might be a clinical technique for discriminating ESCC from normal esophagus, and evaluating outcome in the tumors treated with CRT.

Gene expression of Clonorchis sinensis metacercaria induced by gamma irradiation

Gamma-rays are a form of ionizing radiation and produce serious cellular damage to nuclei and organelles. Gamma irradiation induces the expressions of genes involved in DNA repair. Clonorchis sinensis resides in and provokes pathophysiologic changes in the bile ducts of mammals. The C. sinensis metacercariae are unsusceptible or resistant to gamma irradiation with LD50 of 16.5 Gy. Using the annealing control primer-based polymerase chain reaction (PCR) method, 19 genes were found to be up-regulated in C. sinensis metacercariae exposed to gamma rays. Contigs of up-regulated genes (URGs) were retrieved in a C. sinensis expressed sequence tag pool and extended by DNA-walking. Of the 13 URGs annotated putatively as functional genes, five URGs were associated with energy metabolism, six with protein processing, and the other two with DNA repair protein RAD23 and inhibitor of apoptosis protein. Four URGs were confirmed up-regulated by gamma irradiation by quantitative real-time PCR. One unknown gene, which was up-regulated to the greatest extent, might contribute to early recovery from gamma-irradiation-induced damage. The up-regulations of genes encoding DNA repair, protein processing, and energy metabolism proteins suggests that increases in gene products orchestrate DNA lesion repair and recover cellular functions in gamma-irradiated C. sinensis metacercariae.

Correlation between tumor blood flow assessed by perfusion CT and effect of neoadjuvant therapy in advanced esophageal cancers

BACKGROUND

Redundant blood supply by angiogenesis is a great advantage for the continuous growth of solid tumors. However, with chemotherapy (ChT), it can be disadvantageous due to increased drug delivery. An objective, reproducible, and non-invasive method for evaluating tumor blood supply is offered by perfusion CT.

METHODS

Fifty-five advanced esophageal cancers (95% squamous cell carcinomas) were evaluated for hemodynamic parameters, including blood flow (BF), blood volume (BV), and mean transit time (MTT) of primary tumor by perfusion CT scan. Forty-six underwent neoadjuvant therapy (36 ChT and 10 chemoradiotherapy (CRT)) as primary treatment of the cancer and 36 underwent esophagectomy.

RESULTS

Clinicopathological parameters were not significantly associated with hemodynamic parameters, except for hematogenic metastasis, which was not frequent (seven patients), but significantly associated with high BF (P = 0.0165). High BF and low MTT correlated significantly with a good response by neoadjuvant therapies (P = 0.0004 and P = 0.0124), while BV did not. The patients with high BF more frequently underwent esophagectomy and displayed better prognosis than those with lower values, while neither BV nor MTT was associated with patient survival.

CONCLUSIONS

Tumor BF by perfusion CT can partly predict the effect of ChT and CRT and survival. Further large cohort studies in homogeneous patient groups will reveal its clinical usefulness.

Salvage lymphadenectomy of the right recurrent nerve node with tracheal involvement after definitive chemoradiation therapy for esophageal squamous cell carcinoma: report of two cases

Thoracic esophageal cancers frequently metastasize to the right recurrent nerve nodes (RRNNs). In fact, huge RRNNs invading the trachea sometimes remain after definitive chemoradiation therapy (CRT), despite complete remission of the primary lesion. We performed salvage lymphadenectomy of a large RRNN combined with partial resection of the trachea in two patients. Using an anterior approach, we removed part of the sternum, clavicle, and the first and second costal cartilage; then, we removed the RRNNs with combined resection of the lateral quarter circumference of the trachea, the esophageal wall, and the recurrent nerve. Reconstruction was done with a musculocutaneous patch of major pectoral muscle to cover the tracheal defect. The only minor complication was venous thrombosis in one patient. Thus, combined removal of the RRNN and trachea was performed safely as a salvage operation after definitive CRT for esophageal squamous cell carcinoma.