Abstract
The HER family of receptor tyrosine kinases has been linked to deregulation of growth and proliferation for multiple types of cancer. Members have therefore become thefocus of many drug and immune-based therapy innovations. The targeted anti-cancer agent, lapatinib, is a small molecule inhibitor that directly interferes with EGFR (HER-1)and HER-2 signaling, and indirectly reduces HER-3 signaling, thus suppressing important downstream events. A recently-developed dendritic cell-based vaccine against early breast cancer (ductal carcinoma in situ; DCIS) that generates strong Th1-dominated immunity against HER-2 has induced pathologic complete response in about one-third of immunized individuals. In vitro studies suggested cytokines secreted by Th1 cells could be major contributors to the vaccine effects including induction of apoptosis and suppression of HER expression. With a view toward improving complete response rates, we investigated whether the principle Th1 cytokines (IFN-γ and TNF-α) could act in concert with lapatinib to suppress activity of breast cancer lines in vitro. Lapatinib-sensitive SKBR3, MDA-MB-468 and BT474 cells were incubated with Th1 cytokines, lapatinib, or both. It was found that combined treatment maximized metabolic suppression(Alamar Blue assay), as well as cell death (Trypan Blue) and apoptosis(Annexin V/Propidium Iodide and TMRE staining). Combined drug plus cytokine treatment also maximized suppression of both total and phosphorylated forms of HER-2 and HER-3. Interestingly, when lapatinib resistant lines MDA-MB-453 and JIMT-1 were tested, it was found that the presence of Th1 cytokines appeared to enhance sensitivity for lapatinib-induced metabolic suppression and induction of apoptotic cell death, nearly abrogating drug resistance. These studies provide pre-clinical data suggesting the possibility that targeted drug therapy may be combined with vaccination to enhance anti-cancer effects, and furthermore that robust immunity in the form of secreted Th1 cytokines may have the capacity to mitigate resistance to targeted drugs.
Highlights
Breast cancer exists as a public health crisis throughout the world with about 1.4 million cases of invasive breast cancer (IBC) recorded yearly, leading to approximately 500,000 deaths [1]
To determine whether Th1 cytokines could enhance lapatinib’s effect on breast cancer cells, we studied in detail three cell lines expressing one or more of these HER-family drug targets;SK-BR-3 (HER-2hi/EGFRmed/ERneg), MDA-MB-468 (HER-2neg/ EGFRhi/ERneg and BT-474 (HER-2hi/EGFRmed/ERpos).We began our studies with the Alamar Blue assay, which estimates levels of cellular metabolism via the reduction of resazurin salt to resofurin; a conversion that can be followed spectrophotometrically
We showed that addition of anti-estrogen drugs to cultured ERpos breast cancer lines could greatly enhance cell death when combined with Th1 cytokines [7]
Summary
Breast cancer exists as a public health crisis throughout the world with about 1.4 million cases of invasive breast cancer (IBC) recorded yearly, leading to approximately 500,000 deaths [1]. In follow-onstudies, we demonstrated that the paired combination of the defining Th1 cytokines, IFN-γ and TNF-α, could mediate in vitro many of the effects observed in vaccinated individuals including significant suppression of HER-family RTK surface expression and induced apoptotic cell death in HER family-expressing breast cancer cell lines [6]. These latter studies, demonstrating the potency of multiplexed Th1 cytokines, offer a consistent explanation of how CD4posTh cells, which cannot recognize tumor cells directly, may play a decisive role in their elimination
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
