Evaluation of Vascularity, Blood Perfusion, and Oxygen Tension in Tumor Xenografts with Fluorescent Microscopy

Weekly versus triweekly cisplatin-based concurrent chemoradiotherapy in the treatment of locally advanced cervical carcinoma: An updated meta-analysis based on randomized controlled trials

BACKGROUND

Radiotherapy concurrent with cisplatin is the standard regimen used for treatment of locally advanced cervical carcinoma. In this meta-analysis, survival, recurrence, compliance, and acute adverse effects were compared between weekly and triweekly cisplatin-based concurrent chemoradiotherapy regimens for treatment of cervical cancer.

METHODS

A systematic search for relevant studies was conducted using PubMed, Cochrane Library, EMBASE, and Medline databases. Fixed- or random-effects models were used for pooled analysis. The endpoints were overall survival, recurrence, compliance, and acute adverse effects reported as odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Eight randomized controlled trials met the inclusion criteria. No significant differences were observed between the 2 arms with respect to recurrence, survival, and acute adverse effects (all P > .05). However, the triweekly cisplatin regimen was associated with significantly lower incidence of local recurrence (OR, 1.72; 95% CI, 1.07-2.78; P = .03), radiotherapy completion (OR, 2.08; 95% CI, 0.99-4.38; P = .05), and anemia (OR, 2.10; 95% CI, 1.01-4.37; P = .05), while a weekly cisplatin regimen was associated with a lower risk of leukopenia (OR, 0.57; 95% CI, 0.42-0.92; P = .00) and thrombocytopenia (OR, 0.55; 95% CI, 0.31-0.97; P = .04).

CONCLUSIONS

Triweekly cisplatin-based chemotherapy significantly reduced local recurrence with tolerable toxicity and might be the optimal regimen in concurrent chemoradiotherapy for locally advanced cervical carcinoma.

Acid-Induced Downregulation of ASS1 Contributes to the Maintenance of Intracellular pH in Cancer

Downregulation of the urea cycle enzyme argininosuccinate synthase (ASS1) by either promoter methylation or by HIF1α is associated with increased metastasis and poor prognosis in multiple cancers. We have previously shown that in normoxic conditions, ASS1 downregulation facilitates cancer cell proliferation by increasing aspartate availability for pyrimidine synthesis by the enzyme complex CAD. Here we report that in hypoxia, ASS1 expression in cancerous cells is downregulated further by HIF1α-mediated induction of miR-224-5p, making the cells more invasive and dependent on upstream substrates of ASS1 for survival. ASS1 was downregulated under acidic conditions, and ASS1-depleted cancer cells maintained a higher intracellular pH (pHi), depended less on extracellular glutamine, and displayed higher glutathione levels. Depletion of substrates of urea cycle enzymes in ASS1-deficient cancers decreased cancer cell survival. Thus, ASS1 levels in cancer are differentially regulated in various environmental conditions to metabolically benefit cancer progression. Understanding these alterations may help uncover specific context-dependent cancer vulnerabilities that may be targeted for therapeutic purposes. SIGNIFICANCE: Cancer cells in an acidic or hypoxic environment downregulate the expression of the urea cycle enzyme ASS1, which provides them with a redox and pH advantage, resulting in better survival.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/3/518/F1.large.jpg.