Determination of 2-fluoro-2-deoxy-D-glucose uptake and ATP level for evaluating drug effects in neoplastic cells

Targeting pyruvate kinase M2 contributes to radiosensitivity of non-small cell lung cancer cells in vitro and in vivo

Aerobic glycolysis, a metabolic hallmark of cancer, is associated with radioresistance in non-small cell lung cancer (NSCLC). Pyruvate kinase M2 isoform (PKM2), a key regulator of glycolysis, is expressed exclusively in cancers. However, the impact of PKM2 silencing on the radiosensitivity of NSCLC has not been explored. Here, we show a plasmid of shRNA-PKM2 for expressing a short hairpin RNA targeting PKM2 (pshRNA-PKM2) and demonstrate that treatment with pshRNA-PKM2 effectively inhibits PKM2 expression in NSCLC cell lines and xenografts. Silencing of PKM2 expression enhanced ionizing radiation (IR)-induced apoptosis and autophagy in vitro and in vivo, accompanied by inhibiting AKT and PDK1 phosphorylation, but enhanced ERK and GSK3β phosphorylation. These results demonstrated that knockdown of PKM2 expression enhances the radiosensitivity of NSCLC cell lines and xenografts as well as may aid in the design of new therapies for the treatment of NSCLC.

Early reduction of glucose uptake after cisplatin treatment is a marker of cisplatin sensitivity in ovarian cancer

Cisplatin is an effective chemotherapeutic agent for ovarian cancer, but the sensitivity of cancers differs in individual cases. Because cisplatin is reported to suppress glucose uptake, we investigated the correlation between glucose uptake and sensitivity to the drug. A fluorescent derivative of D-glucose, 2-NBDG (2-[N-(7-nitrobenz-2-oxa-1,3-diaxol-4-yl) amino]-2-deoxyglucose), was used to evaluate glucose uptake. Two ovarian cancer cell lines, SKOV-3 as a relatively resistant line and OVCAR-3 as a relatively sensitive line, were analyzed. Both cell lines had a decreased number of cells accompanied by cell death 24 h after cisplatin treatment, but not at 3 h. In contrast, glucose uptake was decreased 3 h after high-dose cisplatin treatment, which correlated with the sensitivity to the drug at 24 h. The protein levels of glucose transporter 1 (GLUT1) did not change with cisplatin treatment. In contrast, the membrane localization of GLUT1 disappeared after cisplatin treatment. Other cisplatin-resistant cell lines did not show an early decrease in glucose uptake after cisplatin treatment. The early decrease in glucose uptake and later cell death also correlated in cultured cancer cells from ovarian cancer patients. Thus, the decrease in glucose uptake at an early time point after high dose cisplatin treatment reflected cisplatin chemosensitivity in ovarian cancer cells. Measuring glucose uptake might be useful as a rapid evaluation of cisplatin chemosensitivity in ovarian cancer patients.

Specificity of the anti-glycolytic activity of 3-bromopyruvate confirmed by FDG uptake in a rat model of breast cancer

PURPOSE

To evaluate the anti-glycolytic effects of 3-BrPA on rats bearing RMT mammary tumors, by determining FDG uptake after intravenous administration of the therapeutic dose.

MATERIALS AND METHODS

Sixteen rats bearing RMT tumors were treated either with 15 mM 3-BrPA in 2.5 ml of PBS or with 2.5 ml of PBS. After treatment, all rats received FDG and were sacrificed 1 h later.

RESULTS

3-BrPA treatment significantly decreased FDG uptake in tumors by 77% (p = 0.002). FDG uptake did not significantly decrease in normal tissues after treatment.

CONCLUSION

Our study showed that 3-BrPA exhibits a strong anti-glycolytic effect on RMT cells implanted in rats.

The chemopreventive properties of chlorogenic acid reveal a potential new role for the microsomal glucose-6-phosphate translocase in brain tumor progression

Background

Chlorogenic acid (CHL), the most potent functional inhibitor of the microsomal glucose-6-phosphate translocase (G6PT), is thought to possess cancer chemopreventive properties. It is not known, however, whether any G6PT functions are involved in tumorigenesis. We investigated the effects of CHL and the potential role of G6PT in regulating the invasive phenotype of brain tumor-derived glioma cells.

Results

RT-PCR was used to show that, among the adult and pediatric brain tumor-derived cells tested, U-87 glioma cells expressed the highest levels of G6PT mRNA. U-87 cells lacked the microsomal catalytic subunit glucose-6-phosphatase (G6Pase)-α but expressed G6Pase-β which, when coupled to G6PT, allows G6P hydrolysis into glucose to occur in non-glyconeogenic tissues such as brain. CHL inhibited U-87 cell migration and matrix metalloproteinase (MMP)-2 secretion, two prerequisites for tumor cell invasion. Moreover, CHL also inhibited cell migration induced by sphingosine-1-phosphate (S1P), a potent mitogen for glioblastoma multiform cells, as well as the rapid, S1P-induced extracellular signal-regulated protein kinase phosphorylation potentially mediated through intracellular calcium mobilization, suggesting that G6PT may also perform crucial functions in regulating intracellular signalling. Overexpression of the recombinant G6PT protein induced U-87 glioma cell migration that was, in turn, antagonized by CHL. MMP-2 secretion was also inhibited by the adenosine triphosphate (ATP)-depleting agents 2-deoxyglucose and 5-thioglucose, a mechanism that may inhibit ATP-mediated calcium sequestration by G6PT.

Conclusion

We illustrate a new G6PT function in glioma cells that could regulate the intracellular signalling and invasive phenotype of brain tumor cells, and that can be targeted by the anticancer properties of CHL.

[18F] fluoromisonidazole and [18F] fluorodeoxyglucose positron emission tomography in response evaluation after chemo-/radiotherapy of non-small-cell lung cancer: a feasibility study

Background

Experimental and clinical evidence suggest that hypoxia in solid tumours reduces their sensitivity to conventional treatment modalities modulating response to ionizing radiation or chemotherapeutic agents. The aim of the present study was to show the feasibility of determining radiotherapeutically relevant hypoxia and early tumour response by ([¹⁸F] Fluoromisonidazole (FMISO) and [¹⁸F]-2-fluoro-2'-deoxyglucose (FDG) PET.

Methods

Eight patients with non-small-cell lung cancer underwent PET scans. Tumour tissue oxygenation was measured with FMISO PET, whereas tumour glucose metabolism was measured with FDG PET. All PET studies were carried out with an ECAT EXACT 922/47^® scanner with an axial field of view of 16.2 cm. FMISO PET consisted of one static scan of the relevant region, performed 180 min after intravenous administration of the tracer. The acquisition and reconstruction parameters were as follows: 30 min emission scanning and 4 min transmission scanning with 68-Ge/68-Ga rod sources. The patients were treated with chemotherapy, consisting of 2 cycles of gemcitabine (1200 mg/m²) and vinorelbine (30 mg/m²) followed by concurrent radio- (2.0 Gy/d; total dose 66.0 Gy) and chemotherapy with gemcitabine (300–500 mg/m²) every two weeks. FMISO PET and FDG PET were performed in all patients 3 days before and 14 days after finishing chemotherapy.

Results

FMISO PET allowed for the qualitative and quantitative definition of hypoxic sub-areas which may correspond to a localization of local recurrences. In addition, changes in FMISO and FDG PET measure the early response to therapy, and in this way, may predict freedom from disease, as well as overall survival.

Conclusion

These preliminary results warrant validation in larger trials. If confirmed, several novel treatment strategies may be considered, including the early use of PET to evaluate the effectiveness of the selected therapy.

Positron emission tomography in gynecologic cancer

Most positron emission tomography (PET) imaging studies in gynecologic cancer are performed using (18)F-fluorodeoxyglucose (FDG). It contributes valuable information in primary staging of untreated advanced cervical cancer, in the post-treatment surveillance with unexplained tumor marker (such as squamous cell carcinoma antigen [SCC-Ag]) elevation or suspicious of recurrence, and restaging of potentially curable recurrent cervical cancer. Its value in early-stage resectable cervical cancer is questionable. In ovarian cancer, FDG-PET provides benefits for those with plateaued or increasing abnormal serum CA 125 (>35 U/mL), computed tomography and/or magnetic resonance imaging (CT-MRI) defined localized recurrence feasible for local destructive procedures (such as surgery, radiotherapy, or radiofrequency ablation), and clinically suspected recurrent or persistent cancer for which CT-guide biopsy cannot be performed. The role of FDG-PET in endometrial cancer is relatively less defined because of the lack of data in the literature. In our prospective study, FDG-PET coupled with MRI-CT may facilitate optimal management of endometrial cancer in well-selected cases. The clinical impact was positive in 29 (48.3%) of the 60 scans, 22.2% for primary staging, 73.1% for post-therapy surveillance, and 57.1% after salvage therapy, respectively. Scant studies have been reported in the management of vulvar cancer using FDG-PET. More data are needed. Gestational trophoblastic neoplasia is quite unique in biological behavior and clinical management. Our preliminary results suggest that FDG-PET is potentially useful in selected gestational trophoblastic neoplasia by providing a precise metastatic mapping of tumor extent up front, monitoring response, and localizing viable tumors after chemotherapy. The evaluation of a diagnostic tool, such as PET, is usually via comparing the diagnostic efficacy (sensitivity, specificity, etc), by using a more sophisticated receiver operating curve method, or the proportion of treatment been modified. Evaluating PET by clinical benefit is specific to the individual tumor and an attractive new endpoint.

Positron emission tomography imaging in nonmalignant thoracic disorders

The role of the fluorodeoxyglucose (FDG) technique positron emission tomography (PET) is well established in the management of patients with lung cancer. Increasingly, it is becoming evident that FDG-PET can be effectively employed to diagnose a variety of benign pulmonary disorders. Knowledge of such applications further expands the domain of this powerful modality and further improves the ability to differentiate benign from malignant diseases of the chest. We describe pertinent technical factors that substantially contribute to optimal imaging of the thoracic structures. Particularly, the complementary role of attenuation correction (AC) to that of non-AC images is emphasized. We further outline the need for and the state of the art for co-registration of PET and anatomic images for diagnostic and therapeutic purposes. We then review patterns of physiologic uptake of FDG in thoracic structures, including the lung, the heart, the aorta and large arteries, esophagus, thymus, trachea, thoracic muscles, bone marrow, and joints and alterations following radiation therapy to the thorax. A great deal of information is provided with regard to differentiating benign from malignant nodules and in particular, we emphasize the role of dual time point imaging and partial volume correction for accurate assessment of such lesions. Following a brief review of the diagnostic issues related to the assessment of mediastinal adenopathies, the role of FDG-PET imaging in environment-induced lung diseases, including pneumoconiosis, smoking, and asthma are described. A large body of information is provided about the role of this technology in the management of patients with suspected infection and inflammation of the lungs such as acquired immunodeficiency syndrome, fever of unknown origin, sarcoidosis, chronic granulomatous disease and monitoring the disease process and response to therapy. Finally, the value of FDG-PET in differentiating benign from malignant diseases of the pleura including asbestosis-related disorders is described at the conclusion of this comprehensive review.

Positive emission tomography for evaluating a complete clinical response in patients with ovarian or peritoneal carcinoma: correlation with second-look laparotomy

OBJECTIVE

Positive emission tomography (PET) provides a novel means of imaging malignancies. The following study was undertaken to evaluate the predictive value of PET in determining a pathologic complete response in patients with advanced ovarian or peritoneal carcinoma who had a complete clinical response following primary chemotherapy.

METHODS

Twenty-two patients with advanced-stage ovarian (N = 17) or peritoneal (N = 5) carcinoma who had achieved complete clinical and radiologic remission and normal CA-125 level after six cycles of chemotherapy and who had consented to a second look laparotomy procedure were studied. All patients received platinum based therapy and all but one patient, treated elsewhere, received paclitaxel in combination with platinum. Following IV administration of 20 mCi [(18)F]fluorodeoxyglucose (FDG), the entire abdomen and pelvis were scanned. Various technical modifications including bladder activity dilution, intravenous hydration with diuretic therapy, and mechanical bowel preparations, were used to reduce background activity. Second-look laparotomy findings were classified as negative, macroscopically positive if a biopsy of a suspicious area was histologically positive, or microscopically positive if only a nonsuspicious area was histologically positive. The effect of patient preparation prior to PET imaging was evaluated.

RESULTS

Persistent disease was found in 13 of the 22 patients (59%). Only one of nine sites with macroscopic and none of four with microscopic disease were accurately predicted. The sensitivity was only 10% and the specificity 42%. Intravenous hydration, diuretic therapy, and bowel preparation did not improve the results.

CONCLUSIONS

These results suggest that despite technical modifications the sensitivity of PET before second-look laparotomy for small-volume persistent disease is low.

Positron emission tomography using [(18)F]-fluorodeoxy-D-glucose to predict the pathologic response of breast cancer to primary chemotherapy

PURPOSE

To determine whether [(18)F]-fluorodeoxy-D-glucose ([(18)F]-FDG) positron emission tomography (PET) can predict the pathologic response of primary and metastatic breast cancer to chemotherapy.

PATIENTS AND METHODS

Thirty patients with noninflammatory, large (> 3 cm), or locally advanced breast cancers received eight doses of primary chemotherapy. Dynamic PET imaging was performed immediately before the first, second, and fifth doses and after the last dose of treatment. Primary tumors and involved axillary lymph nodes were identified, and the [(18)F]-FDG uptake values were calculated (expressed as semiquantitative dose uptake ratio [DUR] and influx constant [K]). Pathologic response was determined after chemotherapy by evaluation of surgical resection specimens.

RESULTS

Thirty-one primary breast lesions were identified. The mean pretreatment DUR values of the eight lesions that achieved a complete microscopic pathologic response were significantly (P =.037) higher than those from less responsive lesions. The mean reduction in DUR after the first pulse of chemotherapy was significantly greater in lesions that achieved a partial (P =.013), complete macroscopic (P =.003), or complete microscopic (P =.001) pathologic response. PET after a single pulse of chemotherapy was able to predict complete pathologic response with a sensitivity of 90% and a specificity of 74%. Eleven patients had pathologic evidence of lymph node metastases. Mean pretreatment DUR values in the metastatic lesions that responded did not differ significantly from those that failed to respond (P =.076). However, mean pretreatment K values were significantly higher in ultimately responsive cancers (P =.037). The mean change in DUR and K after the first pulse of chemotherapy was significantly greater in responding lesions (DUR, P =.038; K, P =.012).

CONCLUSION

[(18)F]-FDG PET imaging of primary and metastatic breast cancer after a single pulse of chemotherapy may be of value in the prediction of pathologic treatment response.

Assessment of effect of photosensitizers on cytotoxicity of photodynamic therapy in human breast cancer cell cultures

BACKGROUND

Photodynamic therapy (PDT) might be of clinical value for patients with breast cancer with local recurrences or metastasis. However, there is a need for improved photosensitizers that are effective in combination with laser light and have few, if any, side-effects. We evaluated in vitro the effectiveness of a second generation photosensitizer by testing the influence of laser light on cell cultures of a human breast carcinoma cell line, incubated with meta-tetrahydroxyphenylchlorin (m-THPC) (= Temoporfin).

EXPERIMENTAL DESIGN

Five thousand MCF-7 cells were plated in 96-well plates. Forty-eight hours before laser treatment, the cells were plated to achieve a monolayer configuration. Twenty-four hours after plating, they were incubated with m-THPC. On day 6 after treatment with m-THPC we lysed the cells to extract the intracellular ATP that correlates with the number of living cells. The ATP-CVA was used to assess the cytotoxicity of the tested photosensitizer m-THPC at various concentrations and the relevant laser light alone prior to their combination after six days of culture.

RESULTS

We found a dose-response for m-THPC alone ranging from 2 to 16 micrograms/ml. The calculated inhibition concentration to produce 50% cell kill (IC50) was 4.55 micrograms/ml. We also observed a very low cytotoxicity for laser irradiation alone but a very strong cell kill for the combination of m-THPC together with laser light.

CONCLUSIONS

PDT gave almost total cell kill at m-THPC concentrations that are not toxic in vitro.

In vitro potentiation of radiation cytotoxicity by recombinant interferons in cervical cancer cell lines

BACKGROUND

This investigation, which evaluates the combination of radiation and interferon, bridges two clinical treatments of cancer. Radiation therapy (RT) is an integral part of cervical cancer treatment; interferons (IFN), however, are classified as modifiers of biologic response. The authors evaluated the radiation-modulation effects of recombinant alpha-IFN and beta-IFN on two different human cervical cancer cell lines: ME-180 and SiHa. The radiation sensitivity based on the cell growth rate (logarithmic growth phase versus confluence) was also evaluated.

METHODS

Control cells and cells pretreated with either alpha-IFN or beta-IFN were exposed to RT at doses of 0, 2, 5, 10, and 15 Gy. The pretreated cells received IFN at doses of 100, 500, 1000 and 5000 IU/ml for 24 hours. The adenosine triphosphate bioluminescence assay was used to measure the surviving fractions after 7 days of incubation. The data were analyzed using the linear-quadratic model and the radiosensitivity index D. The combined effects of IFN and RT on cytotoxicity were evaluated using the synergistic interaction formula for anticancer agents.

RESULTS

The ME-180 and SiHa cell lines had the same mean inactivation D values of 13.2 when radiated at confluence. Irradiation of ME-180 and SiHa cells in the logarithmic growth phase resulted in mean inactivation D values of 7.5 and 10.2, respectively. Enhanced radiosensitivity was observed in all IFN-RT combinations. Synergism was observed in the majority of experiments.

CONCLUSIONS

Recombinant alpha-IFN and beta-IFN potentiate the radiotoxicity of two cervical cancer cell lines. ME-180 cells were less sensitive to IFN alone than were SiHa cells, but they showed higher a radiosensitizing effect from both IFN. Proliferating cells were more sensitive than confluent cells to RT by itself and to RT-IFN combinations.