Treatment of metastatic renal cell carcinoma

Intraarterial Doxorubicin Infusion Treatment with and without Occlusion of the Renal Artery in Rabbit Renal VX-2 Carcinoma

The aim of this investigation was to establish an animal model for studying fractionated intraarterial treatment of a rabbit kidney VX-2 carcinoma. As repeated catheterizations and drug infusions may cause vascular lesions, we wanted to find whether the rabbit renal artery could be catheterized several times within a short period of time with acceptable iatrogenic vascular trauma. Each of 3 groups of rabbits with implanted renal VX-2 carcinoma were treated 3 times with either 1) temporary renal artery occlusion combined with infusion (occlusion infusion) of a) physiologic saline (OIS) or b) doxorubicin (OID), or 2) with renal artery infusion of doxorubicin. OID was administered in 20 of 21 attempts, OIS in 21 of 24, and infusion of doxorubicin in 20 of 21 attempts. Renal arterial spasm was seen in 5 of 22 rabbits, rarely at the first catheterization, more frequently during the second and third. Permanent iatrogenic vascular trauma occurred in 4 of 15 rabbits after the second and third occlusion infusion. We conclude that the rabbit kidney with implanted VX-2 carcinoma may be a useful model for testing fractionation schemes for multiple intraarterial infusions of antineoplastic drugs.

5-Aza-2'-deoxycytidine suppresses human renal carcinoma cell growth in a xenograft model via up-regulation of the connexin 32 gene

BACKGROUND AND PURPOSE

The connexin (Cx) 32 gene, a member of the gap junction gene family, acts as a tumour suppressor gene in human renal cell carcinoma (RCC) and is down-regulated by the hypermethylation of CpG islands in a promoter region of the Cx gene. The current study investigated whether the restoration of Cx32 silenced by hypermethylation in RCC by a DNA demethylating agent could be an effective treatment against RCC.

EXPERIMENTAL APPROACH

Using nude mice bearing Caki-1 cells (a human metastatic RCC cell line), the effects of 5-aza-2'-deoxycytidine (5-aza-CdR), a DNA demethylase inhibitor, on Cx32 mRNA expression and tumour growth were examined by RT-PCR, and by measuring tumour weight and volume. Cx32 expression in Caki-1 tumours was inhibited by Cx32 short interfering (si) RNA, and the effect of siRNA on 5-aza-CdR-dependent suppression of tumour growth in nude mice was evaluated.

KEY RESULTS

5-aza-CdR treatment inhibited the growth of Caki-1 cells in nude mice by 70% and increased 7-fold the level of Cx32 mRNA. The intratumour injection of Cx32 siRNA almost totally inhibited the expression of Cx32 mRNA and significantly reduced the suppression of tumour growth in 5-aza-CdR-treated nude mice.

CONCLUSIONS AND IMPLICATIONS

5-aza-CdR suppressed the growth of Caki-1 tumours in a xenograft model, by restoring Cx32 expression. This finding suggests that treatment with 5-aza-CdR could be a new effective therapy against human metastatic RCC and that Cx32 could be a potential target for the treatment of RCC.

Connexin 32 as an anti-invasive and anti-metastatic gene in renal cell carcinoma

Cellular homeostasis in many organs is maintained via gap junctions composed of connexin (Cx), a large protein family with a number of isoforms. In fact, gap junctional intercellular communication (GJIC) is actively involved in all aspects of the cellular life cycle, ranging from cell growth to cell death. It has been well known that Cx gene acts as a tumor suppressor gene due to the maintenance of cellular homeostasis via GJIC. On the other hand, recent data show that GJIC-independent function for Cx gene contributes to tumor-suppressive effect of the gene with cell certain specificity. However, the mechanistic aspect of the GJIC-independent function remains largely unknown. In this review, we briefly summarize the tumor-suppressive effects of Cx genes, refer to a new aspect of Cx32 as an anti-invasive and anti-metastatic gene against renal cell carcinoma in a GJIC-independent function and establishment of a new cancer therapy based on the new function of Cx32.

Antitumor effect of irinotecan hydrochloride (CPT-11) on human renal tumors heterotransplanted in nude mice

BACKGROUND

There has been a paucity of antitumor drugs that are active against renal tumors. Irinotecan hydrochloride (CPT-11), a DNA topoisomerase type 1 inhibitor, has demonstrated antitumor activity against human tumors, however, no antitumor effect of CPT-11 on renal tumors has been reported. The antitumor effect of CPT-11 was investigated on 2 human renal tumors (OUR-10 and OUR-20) heterotransplanted into nude mice.

METHODS

Tumor-bearing nude mice were given daily intraperitoneal injections of multiple anticancer drugs suspended in 0.2 mL of phosphate-buffered saline (PBS) 3 times at 3-day intervals. Control mice were injected with 0.2 mL of PBS. The antitumor effects were evaluated by calculating the T/C ratio (treated tumors/controls) of the tumor volume.

RESULTS

Among the 10 anticancer drugs tested, 50 mg/kg of CPT-11 showed an active antitumor effect on OUR-20 (T/C ratio 34). However, all drugs tested on OUR-10 failed to show antitumor activity.

CONCLUSION

Since CPT-11 was effective in 1 of 2 renal tumors examined without severe toxicity, this drug could be a candidate for chemotherapy of renal cell carcinoma.

The use of interferon in renal cell carcinoma

Metastatic renal cell carcinoma remains an incurable disease and current modalities can only offer major palliation to a small percentage of patients. Since treatment is palliative, choice and type of therapy must be carefully considered and reconciled with patient desires. When possible, patients should be offered participation in a clinical trial. For patients choosing progestin therapy, treatment with interferon (IFN) or other biological response modifiers can be instituted at the time of progestin failure. Those patients who have slow tumour progression and maintain a high quality of life can be observed without continued progestin therapy. Although pretreatment characteristics predict response to biologicals, no pretreatment characteristic should preclude an individual patient from a trial of IFN therapy. Whether high-dose interleukin-2 (IL-2), IL-2/lymphocyte-activated killer cells, or IL-2/IFN are superior to IFN alone is uncertain, but clinical trials currently underway should help resolve these issues.

A phase II trial of interleukin-2 by continuous infusion and interferon by intramuscular injection in patients with renal cell carcinoma

Fifteen patients with advanced, measurable renal cell carcinoma entered a Phase II clinical trial of interleukin-2 (IL-2) (Teceleukin, Hoffmann-La Roche Inc., Nutley, NJ) and interferon (IFN) (Roferon A, Hoffmann-La Roche Inc.). IL-2 was administered by continuous infusion daily for 4 days and IFN was administered by intramuscular injection daily for 4 days; therapy continued for 4 weeks. Eight men and seven women were treated in this trial (median age, 61 years). Toxicity was moderate to severe with fatigue, nausea, vomiting, hypotension, and elevated blood urea nitrogen bunion and creatinine levels seen in all patients. Two patients achieved a complete remission and two patients achieved a partial remission. The median duration of response was 18 months. IL-2 and IFN is an active combination in the treatment of renal cell carcinoma and warrants further investigation.

Interferon therapy of metastatic renal cell cancer

There is no curative therapy for metastatic or recurrent renal cell carcinoma (RCC). Almost three-quarters of such patients die of their malignancy in 1 year and less than 5% of such patients are alive at 3 years. Few patients respond to hormonal therapy or chemotherapy, and when responses occur, they are usually brief and partial with little impact on survival. Interferon therapy in metastatic RCC has been associated with response rates of approximately 15-20%, and tumor regression has been demonstrated in patients treated with both partially purified and, more recently, recombinant interferon. Analysis of published trials shows no clear dose-response relationship; however, the highest therapeutic index appears associated with a daily dosage of 5-10 million units. The time to response is variable and may occasionally be prolonged; however, some patients have durations of response exceeding 12 months. Although nephrectomy may be associated with higher response rates, review of available data indicates that nephrectomy has frequently been an eligibility criteria, and indeed there are adequate descriptions of responses in patients that have not undergone this procedure. Patients with pulmonary metastases have the highest response rate. Recently, laboratory and clinical investigations of interferons and several chemotherapeutic agents, notably vinblastine, suggest synergy, but further data is needed to confirm these findings. The role of interferon therapy in improving survival is unknown. There is little doubt, however, that symptomatic patients who respond to interferon therapy may show improvement in their quality of life and prolongation of survival.

Human renal cell carcinoma xenograft: morphology, growth and chemosensitivities

A primary human renal clear cell carcinoma has been developed as a xenograft (JDF-1). Passage 7 of the JDF-1 tumor retained the microscopic morphology of the primary tumor, electron micrographs have confirmed its epithelial characteristics and karyotyping of a subsequent passage has proved it is not a murine hybrid. Immunoperoxidase studies using a panel of murine monoclonal antibodies demonstrate an antigenic phenotype specific for human renal cancer. In vitro chemosensitivities of the JDF-1 tumor were determined by the double-layer soft-agar clonogenic assay method. JDF-1 showed no significant sensitivities to several standard chemotherapeutic agents, but alpha-2-interferon and difluoromethylornithine in combination synergistically inhibited its growth by 74 per cent.