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Targeting breast and prostate cancers through their hormone receptors
Carola Leuschner1, William Hansel
1Pennington Biomedical Research Center, Baton Rouge, Louisiana 70808, USA.
Abstract:
A targeted treatment that effectively destroys human breast, prostate, ovarian, and testicular cancer cells that express luteinizing hormone/chorionic gonadotropin (LH/CG) receptors has been developed. The treatment consists of a conjugate of a membrane-disrupting lytic peptide (Hecate, Phor14, or Phor21) and a 15-amino acid segment of the beta chain of CG. Because these conjugates act primarily by destroying cell membranes, their effects are independent of cell proliferation. The conjugates are relatively small molecules, are rapidly metabolized, and are not antigenic. In a series of independent experiments conducted in three different laboratories, the validity of the concept has been established, and it has been shown that the LH/CG receptor capacity of the cancer cells is directly related to the sensitivity of the lytic peptide conjugates. Sensitivity to the drugs can be increased by pretreating prostate or breast cancer cells with FSH or estradiol to up-regulate LH/CG receptors. A series of 23 in vivo experiments involving a total of 1630 nude mice bearing xenografts of human prostate or breast cancer cells showed convincingly that all three lytic peptide-betaCG compounds were highly effective in destroying tumors and reducing tumor burden. Hecate-betaCG was less effective in mice bearing ovarian epithelial cancer cell xenografts, but was highly effective in treating granulosa cell tumors in transgenic mice. In addition, Hecate-betaCG and Phor14-betaCG were highly effective in targeting and destroying prostate and breast cancer cell metastases in the presence or absence of the primary tumors. Although effective in vitro, neither Hecate nor Phor14 alone were effective in reducing primary tumor volume or burden in nude mice bearing prostate or breast cancer xenografts.
Insights
A novel cancer treatment targets cells expressing luteinizing hormone/chorionic gonadotropin (LH/CG) receptors using lytic peptide-betaCG conjugates. This targeted approach effectively destroys various cancer cells and metastases, offering a promising new therapeutic strategy.
Area of Science:
- Oncology
- Molecular Biology
- Drug Development
Background:
- Luteinizing hormone/chorionic gonadotropin (LH/CG) receptors are expressed on several human cancer cells, including breast, prostate, ovarian, and testicular cancers.
- Targeting these receptors offers a potential strategy for selective cancer therapy.
- Previous approaches have limitations in efficacy or specificity.
Purpose of the Study:
- To develop and evaluate a novel targeted cancer therapy utilizing conjugates of lytic peptides and a segment of the beta chain of CG.
- To assess the efficacy of these conjugates against various cancer types, including solid tumors and metastases.
- To investigate methods for enhancing treatment sensitivity.
Main Methods:
- Conjugates were synthesized combining membrane-disrupting lytic peptides (Hecate, Phor14, Phor21) with a 15-amino acid segment of the beta chain of CG.
- In vitro studies assessed conjugate activity against cancer cells expressing LH/CG receptors.
- In vivo experiments were conducted using 1630 nude mice bearing xenografts of human prostate or breast cancer, as well as transgenic mice with ovarian cancer.
- Sensitivity was modulated by up-regulating LH/CG receptors using FSH or estradiol.
Main Results:
- The lytic peptide-betaCG conjugates demonstrated significant efficacy in destroying human breast, prostate, and ovarian cancer cells in vitro.
- In vivo studies showed all three conjugates were highly effective in destroying tumors and reducing tumor burden in mice with prostate and breast cancer xenografts.
- Hecate-betaCG was effective against granulosa cell tumors and also targeted metastases for prostate and breast cancers.
- Sensitivity to conjugates correlated directly with LH/CG receptor expression, which could be enhanced by FSH or estradiol pretreatment.
Conclusions:
- Lytic peptide-betaCG conjugates represent a potent targeted therapy for cancers expressing LH/CG receptors.
- The treatment mechanism, based on membrane disruption, is independent of cell proliferation.
- The conjugates show high efficacy against primary tumors and metastases, with potential for enhanced sensitivity through receptor up-regulation.
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