Cytomegalovirus (CMV) is a highly prevalent and globally distributed virus. CMV infection in healthy adults is usually asymptomatic or causes a mild mononucleosis-like syndrome. CMV disease causes significant morbidity and mortality in neonates and severely immunocompromised adults. CMV disease can present with a wide range of manifestations, with colitis being the most common. The incidence of severe CMV disease in immunocompetent adults appears to be greater than previously thought, which may be partly due to immune dysfunction related to comorbidities such as kidney disease or diabetes mellitus. CMV disease can mimic an array of alternative diagnoses and pose a significant diagnostic challenge, especially in immunocompetent adults, leading to delayed diagnosis, adverse health outcomes and unnecessary financial expense. Non-invasive testing for CMV is widely available and can facilitate early diagnosis if used appropriately. Although limited, current evidence suggests that targeted antiviral therapy with ganciclovir or valganciclovir is appropriate for severe CMV disease in immunocompetent adults.

Calcium signaling is a key regulator of pathways important in tumor progression, such as proliferation and apoptosis. Most studies assessing altered calcium homeostasis in cancer cells have focused on alterations mediated through changes in cytoplasmic free calcium levels. Here, we show that basal-like breast cancers are characterized by an alteration in the secretory pathway calcium ATPase 1 (SPCA1), a calcium pump localized to the Golgi. Inhibition of SPCA1 in MDA-MB-231 cells produced pronounced changes in cell proliferation and morphology in three-dimensional culture, without alterations in sensitivity to endoplasmic reticulum stress induction or changes in global calcium signaling. Instead, the effects of SPCA1 inhibition in MDA-MB-231 cells reside in altered regulation of calcium-dependent enzymes located in the secretory pathway, such as proprotein convertases. Inhibition of SPCA1 produced a pronounced alteration in the processing of insulin-like growth factor receptor (IGF1R), with significantly reduced levels of functional IGF1Rβ and accumulation of the inactive trans-Golgi network pro-IGF1R form. These studies identify for the first time a calcium transporter associated with the basal-like breast cancer subtype. The pronounced effects of SPCA1 inhibition on the processing of IGF1R in MDA-MB-231 cells independent of alterations in global calcium signaling also demonstrate that some calcium transporters can regulate the processing of proteins important in tumor progression without major alterations in cytosolic calcium signaling. Inhibitors of SPCA1 may offer an alternative strategy to direct inhibitors of IGF1R and attenuate the processing of other proprotein convertase substrates important in basal breast cancers.

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