Prediction of tumor differentiation using sequential PET/CT and MRI in patients with breast cancer

Transport Metabolons and Acid/Base Balance in Tumor Cells

Solid tumors are metabolically highly active tissues, which produce large amounts of acid. The acid/base balance in tumor cells is regulated by the concerted interplay between a variety of membrane transporters and carbonic anhydrases (CAs), which cooperate to produce an alkaline intracellular, and an acidic extracellular, environment, in which cancer cells can outcompete their adjacent host cells. Many acid/base transporters form a structural and functional complex with CAs, coined "transport metabolon". Transport metabolons with bicarbonate transporters require the binding of CA to the transporter and CA enzymatic activity. In cancer cells, these bicarbonate transport metabolons have been attributed a role in pH regulation and cell migration. Another type of transport metabolon is formed between CAs and monocarboxylate transporters, which mediate proton-coupled lactate transport across the cell membrane. In this complex, CAs function as "proton antenna" for the transporter, which mediate the rapid exchange of protons between the transporter and the surroundings. These transport metabolons do not require CA catalytic activity, and support the rapid efflux of lactate and protons from hypoxic cancer cells to allow sustained glycolytic activity and cell proliferation. Due to their prominent role in tumor acid/base regulation and metabolism, transport metabolons might be promising drug targets for new approaches in cancer therapy.

Dual time point 18F-fluorodeoxyglucose positron emission tomography/computed tomography fusion imaging (18F-FDG PET/CT) in primary breast cancer

BACKGROUND

To evaluate the clinicopathological and prognostic significance of the percentage change between maximum standardized uptake value (SUV_max) at 60 min (SUV_max1) and SUV_max at 120 min (SUV_max2) (ΔSUV_max%) using dual time point ¹⁸F-fluorodeoxyglucose emission tomography/computed tomography (¹⁸F-FDG PET/CT) in breast cancer.

METHODS

Four hundred and sixty-four patients with primary breast cancer underwent ¹⁸F-FDG PET/CT for preoperative staging. ΔSUV_max% was defined as (SUV_max2 - SUV_max1) / SUV_max1 × 100. We explored the optimal cutoff value of SUV_max parameters (SUV_max1 and ΔSUV_max%) referring to the event of relapse by using receiver operator characteristic curves. The clinicopathological and prognostic significances of the SUV_max1 and ΔSUV_max% were analyzed by Cox's univariate and multivariate analyses.

RESULTS

The optimal cutoff values of SUV_max1 and ΔSUV_max% were 3.4 and 12.5, respectively. Relapse-free survival (RFS) curves were significantly different between high and low SUV_max1 groups (P = 0.0003) and also between high and low ΔSUV_max% groups (P = 0.0151). In Cox multivariate analysis for RFS, SUV_max1 was an independent prognostic factor (P = 0.0267) but ΔSUV_max% was not (P = 0.152). There was a weak correlation between SUV_max1 and ΔSUV_max% (P < 0.0001, R² = 0.166). On combining SUV_max1 and ΔSUV_max%, the subgroups of high SUV_max1 and high ΔSUV_max% showed significantly worse prognosis than the other groups in terms of RFS (P = 0.0002).

CONCLUSION

Dual time point ¹⁸F-FDG PET/CT evaluation can be a useful method for predicting relapse in patients with breast cancer. The combination of SUV_max1 and ΔSUV_max% was able to identify subgroups with worse prognosis more accurately than SUV_max1 alone.

CAIX forms a transport metabolon with monocarboxylate transporters in human breast cancer cells

Tumor cells rely on glycolysis to meet their elevated demand for energy. Thereby they produce significant amounts of lactate and protons, which are exported via monocarboxylate transporters (MCTs), supporting the formation of an acidic microenvironment. The present study demonstrates that carbonic anhydrase IX (CAIX), one of the major acid/base regulators in cancer cells, forms a protein complex with MCT1 and MCT4 in tissue samples from human breast cancer patients, but not healthy breast tissue. Formation of this transport metabolon requires binding of CAIX to the Ig1 domain of the MCT1/4 chaperon CD147 and is required for CAIX-mediated facilitation of MCT1/4 activity. Application of an antibody, directed against the CD147-Ig1 domain, displaces CAIX from the transporter and suppresses CAIX-mediated facilitation of proton-coupled lactate transport. In cancer cells, this "metabolon disruption" results in a decrease in lactate transport, reduced glycolysis, and ultimately reduced cell proliferation. Taken together, the study shows that carbonic anhydrases form transport metabolons with acid/base transporters in human tumor tissue and that these interactions can be exploited to interfere with tumor metabolism and proliferation.

Can apparent diffusion coefficient (ADC) distinguish breast cancer from benign breast findings? A meta-analysis based on 13 847 lesions

BACKGROUND

The purpose of the present meta-analysis was to provide evident data about use of Apparent Diffusion Coefficient (ADC) values for distinguishing malignant and benign breast lesions.

METHODS

MEDLINE library and SCOPUS database were screened for associations between ADC and malignancy/benignancy of breast lesions up to December 2018. Overall, 123 items were identified. The following data were extracted from the literature: authors, year of publication, study design, number of patients/lesions, lesion type, mean value and standard deviation of ADC, measure method, b values, and Tesla strength. The methodological quality of the 123 studies was checked according to the QUADAS-2 instrument. The meta-analysis was undertaken by using RevMan 5.3 software. DerSimonian and Laird random-effects models with inverse-variance weights were used without any further correction to account for the heterogeneity between the studies. Mean ADC values including 95% confidence intervals were calculated separately for benign and malign lesions.

RESULTS

The acquired 123 studies comprised 13,847 breast lesions. Malignant lesions were diagnosed in 10,622 cases (76.7%) and benign lesions in 3225 cases (23.3%). The mean ADC value of the malignant lesions was 1.03 × 10^- 3 mm²/s and the mean value of the benign lesions was 1.5 × 10^- 3 mm²/s. The calculated ADC values of benign lesions were over the value of 1.00 × 10^- 3 mm²/s. This result was independent on Tesla strength, choice of b values, and measure methods (whole lesion measure vs estimation of ADC in a single area).

CONCLUSION

An ADC threshold of 1.00 × 10^- 3 mm²/s can be recommended for distinguishing breast cancers from benign lesions.

Correlation Between Doppler Ultrasound Blood Flow Parameters and Angiogenesis and Proliferation Activity in Breast Cancer

BACKGROUND The aim of this study was to assess the correlation between Doppler ultrasound blood flow parameters and angiogenesis and proliferation activity in breast cancer. MATERIAL AND METHODS We enrolled breast cancer patients (n=55) and benign tumor patients (n=40) from Tengzhou Central People's Hospital from Mar 2014 to Dec 2016. Doppler ultrasound examination was conducted to determine blood flow parameters, and immunohistochemistry (IHC) experiments were performed to determine the protein expression of angiogenesis genes, cell proliferation genes, and tumor-suppressor genes. RESULTS Compared with benign tumors, the maximum velocity (Vmax) and resistance index (RI) were significantly different in I-II stage and III-IV stage breast cancer (P<0.01 and P<0.001, respectively). IHC assay showed that VEDGF165, NRP-1, SphK1, CD31, YAP, CTGF, and Gli2 proteins expressions were significantly higher in breast cancer patients (P<0.01 and P<0.001, respectively). PTEN and MFN2 protein expressions of breast cancer patients were significantly lower (P<0.01 or P<0.001, respectively) compared with those of benign tumor patients. VEDGF165, NRP-1, SphK1, CD31, YAP, CTGF, and Gli2 proteins expressions were positively correlated with Vmax and negatively correlated with RI in breast cancer. PTEN and MFN2 protein expressions were negative correlated with Vmax and positively correlated with RI in breast cancer patients. CONCLUSIONS Decreased RI and increased Vmax are correlated with angiogenesis, proliferation, and tumor suppression in breast cancer.