Upregulation of CRMP4, a new prostate cancer metastasis suppressor gene, inhibits tumor growth in a nude mouse intratibial injection model

Direct bone marrow injection of human bone marrow-derived stromal cells into mouse femurs results in greater prostate cancer PC-3 cell proliferation, but not specifically proliferation within the injected femurs

Background

While prostate cancer (PCa) cells most often metastasize to bone in men, species-specific differences between human and mouse bone marrow mean that this pattern is not faithfully replicated in mice. Herein we evaluated the impact of partially humanizing mouse bone marrow with human bone marrow-derived stromal cells (BMSC, also known as "mesenchymal stem cells") on human PCa cell behaviour.

Methods

BMSC are key cellular constituents of marrow. We used intrafemoral injection to transplant 5 × 10⁵ luciferase (Luc) and green fluorescence protein (GFP) expressing human BMSC (hBMSC-Luc/GFP) into the right femur of non-obese diabetic (NOD)-severe combined immunodeficiency (scid) interleukin (IL)-2γ^−/− (NSG) mice. Two weeks later, 2.5 × 10⁶ PC-3 prostate cancer cells expressing DsRed (PC-3-DsRed) were delivered into the mice via intracardiac injection. PC-3-DsRed cells were tracked over time using an In Vivo Imaging System (IVIS) live animal imaging system, X-ray and IVIS imaging performed on harvested organs, and PC-3 cell numbers in femurs quantified using flow cytometry and histology.

Results

Flow cytometry analysis revealed greater PC-3-DsRed cell numbers within femurs of the mice that received hBMSC-Luc/GFP. However, while there were overall greater PC-3-DsRed cell numbers in these animals, there were not more PC-3-DsRed in the femurs injected with hBMSC-Luc/GFP than in contralateral femurs. A similar proportion of mice in with or without hBMSC-Luc/GFP had bone lessions, but the absolute number of bone lesions was greater in mice that had received hBMSC-Luc/GFP.

Conclusion

PC-3-DsRed cells preferentially populated bones in mice that had received hBMSC-Luc/GFP, although PC-3-DsRed cells not specifically localize in the bone marrow cavity where hBMSC-Luc/GFP had been transplanted. hBMSC-Luc/GFP appear to modify mouse biology in a manner that supports PC-3-DsRed tumor development, rather than specifically influencing PC-3-DsRed cell homing. This study provides useful insights into the role of humanizing murine bone marrow with hBMSC to study human PCa cell biology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09430-6.

Collapsin response mediator protein 4 enhances the radiosensitivity of colon cancer cells through calcium‑mediated cell signaling

Radiation therapy is an effective treatment against various types of cancer, but some radiation‑resistant cancer cells remain a major therapeutic obstacle; thus, understanding radiation resistance mechanisms is essential for cancer treatment. In this study, we established radiation‑resistant colon cancer cell lines and examined the radiation‑induced genetic changes associated with radiation resistance. Using RNA‑sequencing analysis, collapsin response mediator protein 4 (<em>CRMP4</em>) was identified as the candidate gene associated with radiation sensitivity. When cells were exposed to radiation, intracellular Ca²⁺ influx, collapse of mitochondrial membrane potential, and cytochrome c release into the cytosol were increased, followed by apoptosis induction. Radiation treatment‑ or Ca²⁺ ionophore A23187‑induced apoptosis was significantly inhibited in <em>CRMP4</em>‑deficient cells, including radiation‑resistant or <em>CRMP4</em>‑shRNA cell lines. Furthermore, treatment of <em>CRMP4</em>‑deficient cells with low levels (&lt;5 µM) of BAPTA‑AM, a Ca²⁺ chelator, resulted in radiation resistance. Conversely, Ca²⁺ deficiency induced by a high BAPTA‑AM concentration (&gt;10 µM) resulted in higher cell death in the <em>CRMP4</em>‑depleted cells compared to <em>CRMP4</em>‑expressing control cells. Our results suggest that <em>CRMP4</em> plays an important role in Ca²⁺‑mediated cell death pathways under radiation exposure and that CRMP4 may be a therapeutical target for colon cancer treatment.

Dovitinib dilactic acid reduces tumor growth and tumor-induced bone changes in an experimental breast cancer bone growth model

Advanced breast cancer has a high incidence of bone metastases. In bone, breast cancer cells induce osteolytic or mixed bone lesions by inducing an imbalance in bone formation and resorption. Activated fibroblast growth factor receptors (FGFRs) are important in regulation of tumor growth and bone remodeling. In this study we used FGFR1 and FGFR2 gene amplifications containing human MFM223 breast cancer cells in an experimental xenograft model of breast cancer bone growth using intratibial inoculation technique. This model mimics bone metastases in breast cancer patients. The effects of an FGFR inhibitor, dovitinib dilactic acid (TKI258) on tumor growth and tumor-induced bone changes were evaluated. Cancer-induced bone lesions were smaller in dovitinib-treated mice as evaluated by X-ray imaging. Peripheral quantitative computed tomography imaging showed higher total and cortical bone mineral content and cortical bone mineral density in dovitinib-treated mice, suggesting better preserved bone mass. CatWalk gait analysis indicated that dovitinib-treated mice experienced less cancer-induced bone pain in the tumor-bearing leg. A trend towards decreased tumor growth and metabolic activity was observed in dovitinib-treated mice quantified by positron emission tomography imaging with 2-[¹⁸F]fluoro-2-deoxy-D-glucose at the endpoint. We conclude that dovitinib treatment decreased tumor burden, cancer-induced changes in bone, and bone pain. The results suggest that targeting FGFRs could be beneficial in breast cancer patients with bone metastases.

DPYSL3 modulates mitosis, migration, and epithelial-to-mesenchymal transition in claudin-low breast cancer

A Clinical Proteomic Tumor Analysis Consortium (CPTAC) proteogenomic analysis prioritized dihydropyrimidinase-like-3 (DPYSL3) as a multilevel (RNA/protein/phosphoprotein) expression outlier specific to the claudin-low (CLOW) subset of triple-negative breast cancers. A PubMed informatics tool indicated a paucity of data in the context of breast cancer, which further prioritized DPYSL3 for study. DPYSL3 knockdown in DPYSL3-positive ([Formula: see text]) CLOW cell lines demonstrated reduced proliferation, yet enhanced motility and increased expression of epithelial-to-mesenchymal transition (EMT) markers, suggesting that DPYSL3 is a multifunctional signaling modulator. Slower proliferation in DPYSL3-negative ([Formula: see text]) CLOW cells was associated with accumulation of multinucleated cells, indicating a mitotic defect that was associated with a collapse of the vimentin microfilament network and increased vimentin phosphorylation. DPYSL3 also suppressed the expression of EMT regulators SNAIL and TWIST and opposed p21 activated kinase 2 (PAK2)-dependent migration. However, these EMT regulators in turn induce DPYSL3 expression, suggesting that DPYSL3 participates in negative feedback on EMT. In conclusion, DPYSL3 expression identifies CLOW tumors that will be sensitive to approaches that promote vimentin phosphorylation during mitosis and inhibitors of PAK signaling during migration and EMT.

CRMP4a suppresses cell motility by sequestering RhoA activity in prostate cancer cells

Objectives: Distant metastasis is a critical factor for cancer-associated death. Our previous studies identified collapsin response mediator protein 4a (CRMP4a) as a metastasis suppressor in prostate cancers. Enhancing CRMP4 expression by promoter-targeted small activating RNAs reduced cell migration in vitro and abolished distal metastasis in mouse xenograft models. In this study, we investigated the mechanism for CRMP4a-mediated suppression of cell migration. Methods: PC-3 cells were stably infected with lentiviruses expressing CRMP4a cDNA or a shRNA sequence. Cytoskeletal organization was analyzed by measuring cellular focal adhesion area and number, percentage of cell area and lamellipodia numbers after phalloidin staining or anti-vinculin immunocytofluorescent staining. Cell migration was evaluated with Transwell^TM chambers coated with MatriGel. RhoA activation was determined with a Rhotekin RBD agarose bead-based assay kit. Lentiviruses harboring RhoA-Q63L or RhoA-T19N mutant constructs were used to overexpress mutant RhoA proteins. Results: CRMP4a overexpression largely reduced while CRMP4a knockdown remarkably increased cytoskeletal organization in PC-3 cells. CRMP4a immunoprecipitation pulled down RhoA but not cdc42 or Rac1 proteins. Manipulating CRMP4a expression levels reversely altered active RhoA levels. Overexpression of RhoA active (Q63L) but not inactive (T19N) mutants reversed CRMP4a-mediated reduction of cancer cell migration while RhoA inhibitor Rhosin diminished CRMP4a shRNA-induced increase of cancer cell migration. CRMP4a overexpression also largely reduced cell spreading that was abolished by overexpressing RhoA active mutant. Conclusion: Our data demonstrated that CRMP4a interacts with RhoA and sequesters its activity, resulting in suppression of cytoskeletal organization, cell migration and spreading.

Targeting CRMP-4 by lentivirus-mediated RNA interference inhibits SW480 cell proliferation and colorectal cancer growth

The aim of the present study was to investigate the expression level of collapsin response mediator protein 4 (CRMP-4) in human colorectal cancer (CRC) tissue and to evauluate its impact on SW480 cell proliferation, in addition to tumor growth in a mouse xenograft model. Clinical CRC tissue samples were collected to detect the CRMP-4 protein expression levels using western blot and immunohistochemistry analyses. A specific small interfering RNA sequence targeting the CRMP-4 gene (DPYSL3) was constructed and transfected into an SW480 cell line using a lentivirus vector to obtain a stable cell line with low expression of CRMP-4. The effectiveness of the interference was evaluated using western blot and reverse transcription-quantitative polymerase chain reaction, and the cell proliferation was determined using MTT and BrdU colorimetric methods. Tumor growth was assessed by subcutaneously inoculating the constructed cells into BALB/c nude mice. The protein expression levels of CRMP-4 were markedly increased in colon tumor tissue of the human samples. The proliferation of SW480 cells and the tumor growth rate in nude mice of the si-CPMR-4 group were evidently depressed compared with the si-scramble group. Thus, the present results suggest that CRMP-4 may be involved in the pathogenesis of CRC.

Collapsin response mediator protein 4 isoforms (CRMP4a and CRMP4b) have opposite effects on cell proliferation, migration, and invasion in gastric cancer

Background

Collapsin response mediator proteins (CRMPs) were originally identified in the nervous system and are involved in neuronal development. Similar to CRMP1, CRMP4 has a shorter transcript encoding a short isoform known as CRMP4a, and a longer transcript encoding a long isoform known as CRMP4b. Previous studies have shown that CRMP4a and CRMP4b exhibit opposing functions in neurite outgrowth. In the present study, we aimed to determine whether CRMP4a and CRMP4b have divergent effects in gastric cancer.

Methods

We first analyzed the mRNA and protein expression levels of CRMP4a and CRMP4b in surgical resected specimens, gastric cancer cell lines and normal gastric epithelial cell line GES-1 by quantitative real-time PCR. Open reading frame and CRMP4b shRNA were generated by lentivirus package and stable cells stably expressing CRMP4a open reading frame and CRMP4b shRNA were constructed. Then the roles of CRMP4a and CRMP4b in cell proliferation, cell cycle progression, apoptosis, migration, invasion, and adhesion were determined by cell proliferation assays, flow cytometry analysis, transwell migration and invasion assays, cell Adhesion Assay, and tumorigenicity assays in nude mice, respectively.

Results

CRMP4a expression was lower and CRMP4b expression was higher in tumor tissue samples as compared to paired non-tumor tissue samples. Additionally, CRMP4a expression was lower and CRMP4b expression was higher in gastric cancer cell lines than in the normal gastric epithelial cell line GES-1. CRMP4a overexpression and CRMP4b silencing suppressed cell proliferation in vitro and in vivo. Additionally, CRMP4a overexpression and CRMP4b silencing induced a significant G1-phase arrest and a decrease of the percentage of cells in S-phase. Furthermore, CRMP4a overexpression and CRMP4b silencing inhibited cell migration, invasion, and adhesion. However, neither CRMP4a overexpression nor CRMP4b silencing affected apoptosis.

Conclusion

These results indicate that CRMP4a and CRMP4b have opposite effects on cell proliferation, migration, and invasion in gastric cancer.

Enhancing DPYSL3 gene expression via a promoter-targeted small activating RNA approach suppresses cancer cell motility and metastasis

To explore a novel strategy in suppressing tumor metastasis, we took the advantage of a recent RNA activation (RNAa) theory and used small double-strand RNA molecules, termed as small activating RNAs (saRNA) that are complimentary to target gene promoter, to enhance transcription of metastasis suppressor gene. The target gene in this study is Dihydro-pyrimidinase-like 3 (DPYSL3, protein name CRMP4), which was identified as a metastatic suppressor in prostate cancers. There are two transcriptional variants of DPYSL3 gene in human genome, of which the variant 2 is the dominant transcript (DPYSL3v2, CRMP4a) but is also significantly down-regulated in primary prostate cancers. A total of 8 saRNAs for DPYSL3v1 and 14 saRNAs for DPYSL3v2 were tested in multiple prostate cancer cell lines. While none of the saRNAs significantly altered DPYSL3v1 expression, 4 saRNAs showed a strong enhancing effect on DPYSL3v2 expression, resulting in reduced cell mobility in vitro. To achieve a prostate cancer-specific delivery for in vivo testing, we conjugated the most potent saV2-9 RNA molecule with the prostate-specific membrane antigen (PSMA)-targeting aptamer A10-3.2. The conjugates successful increased DPYSL3v2 gene expression in PSMA-positive but not PSMA-negative prostate cancer cells. In nude mice bearing orthotopic xenograft of prostate cancer, a 10-day consecutive treatment with the saV2-9 conjugates significantly suppress distal metastasis compared to the control saRNAs. Analysis of xenograft tissues revealed that DPYSL3v2 expression was largely increased in saV2-9 conjugate-treated group compared to the control group. In conclusion, DPYSL3v2 promoter-targeted saRNA molecules might be used as an adjunctive therapy to suppress prostate cancer metastasis.