[Detection of second tumors in 11C-choline PET/CT studies performed due to biochemical recurrence of prostate cancer]

Molecular and Functional Characterization of Choline Transporter-Like Proteins in Esophageal Cancer Cells and Potential Therapeutic Targets

In this study, we examined the molecular and functional characterization of choline uptake in the human esophageal cancer cells. In addition, we examined the influence of various drugs on the transport of [³H]choline, and explored the possible correlation between the inhibition of choline uptake and apoptotic cell death. We found that both choline transporter-like protein 1 (CTL1) and CTL2 mRNAs and proteins were highly expressed in esophageal cancer cell lines (KYSE series). CTL1 and CTL2 were located in the plasma membrane and mitochondria, respectively. Choline uptake was saturable and mediated by a single transport system, which is both Na⁺-independent and pH-dependent. Choline uptake and cell viability were inhibited by various cationic drugs. Furthermore, a correlation analysis of the potencies of 47 drugs for the inhibition of choline uptake and cell viability showed a strong correlation. Choline uptake inhibitors and choline deficiency each inhibited cell viability and increased caspase-3/7 activity. We conclude that extracellular choline is mainly transported via a CTL1. The functional inhibition of CTL1 by cationic drugs could promote apoptotic cell death. Furthermore, CTL2 may be involved in choline uptake in mitochondria, which is the rate-limiting step in S-adenosylmethionine (SAM) synthesis and DNA methylation. Identification of this CTL1- and CTL2-mediated choline transport system provides a potential new target for esophageal cancer therapy.

Detection of a second malignancy in prostate cancer patients by using [(18)F]Choline PET/CT: a case series

BACKGROUND

The role of radiolabeled choline (Cho) in patients with biochemical recurrence after radical treatment for prostate cancer (PCa) is well established. Its widespread clinical use has prompted the depiction of incidentalomas, unusual sites of metastatic lesions, as well as false positive and negative cases. We reported a series of patients affected by biochemical recurrence of PCa imaged by [(18)F]Cho positron emission tomography/computed tomography (PET/CT) which resulted suspected for a second malignancy.

CASE PRESENTATION

[(18)F]Cho PET/CT was performed in patients with biochemical PCa recurrence. From an internal clinical database we identified patients in which PET/CT resulted suspected for a second malignancy. A second malignancy was suspected in presence of "unusual" site of [(18)F]Cho uptake not consistent with clinical-instrumental history. Histology was used as reference standard for final diagnosis. Seven PCa patients (76 years, 71-84 years) with the suspicion of a second tumor based on [(18)F]Cho PET/CT findings were identified. Mean value of PSA at the time of [(18)F]Cho PET/CT was 2,37 ng/mL. The median time between PCa diagnosis and PET/CT was 6 years (range 0-14 years). In two cases history of a second malignancy (lung cancer and cutaneous basocellular carcinoma) was known (diagnosed 12 and 6 years after PCa, respectively). PET/CT identified 13 sites of [(18)F]Cho uptake (lung = 5, lymph node = 7, bone = 1). Final diagnosis was consistent with lung cancer in 5/7 cases (first diagnosis = 4/5, recurrence = 1/5), colorectal cancer and nodal metastases from melanoma in 1 case each.

CONCLUSIONS

Although the clinical usefulness of Cho PET/CT for detecting cancer lesions other than prostate origin is known, for those patients who undergo this examination according to indication, the diagnosis of a second tumor has a significant impact on their therapeutic management.